CAS course on "RF for Accelerators", 18 June - 01 July 2023, Berlin Germany

18 Jun 2023, 08:30 → 1 Jul 2023, 19:30 Europe/Zurich

Frank Tecker (CERN)

 

The CERN Accelerator School organizes in collaboration with the Helmholtz-Zentrum Berlin (HZB) a course for 'RF for Accelerators'.

This unique 2-week residential course will mainly be of interest to staff in accelerator laboratories, university departments or companies involved in producing RF equipment for accelerators. The course will include a review of the RF technology presently used in the field of particle accelerators as well as a recapitulation of the theoretical fundamentals.

Different RF equipment and RF technologies will be discussed along with their practical applications for various types of accelerators. Dedicated "hands-on" afternoon courses  and seminars will complete the programme.

Due to the afternoon courses the maximum number of participants will be limited. The principle of "first come first served" will be applied.

It is recommended that participants register as soon as possible, first come first served as there may be a limited number of participants due to limitations of the hotel facilities and hands-on courses.

Sunday 18 June

1 Arrival day and registration

19:30 Dinner

Monday 19 June

2 Opening

Speakers: Christine Vollinger (CERN), Frank Tecker (CERN), Jens Knobloch (Helmholtz-Zentrum Berlin & Universität Siegen)

2023-06-CAS-Intro_HZB-final.pptx

opening-rf-2023.pdf

opening-rf-2023.pptx

Recording

Video preview

VretenarVollinger_CAS_RF_ 2023_Intro.pdf

VretenarVollinger_CAS_RF_ 2023_Intro.pptx

3 Theory of EM fields I

"
In the presentation theoretical foundations of electromagnetic fields are reviewed. First, general terms and concepts of field theory are discussed (scalar fields, vector fields, normal and tangential fields, dot product, cross product etc.) and then Maxwell’s equations in the integral form and material equations are recapitulated. It is shown how Maxwell’s equations in the integral form are transferred to the differential form by considering infinitely small Gaussian volumes and area elements. In this context, various vector operators are repeated and their properties are discussed. Based on properties of these vector operators, conservation principles such as conservation of charges and conservation of energy are derived and interpreted. In the second part of the talk, field problems described by Maxwell’s equations are classified into electro-static, magneto-static and full-wave solutions. Poisson equation for electric potentials, Poisson equation for magnetic vector potentials, curl-curl equation and wave equation as well as Helmholtz equation in 2D and 3D are derived from Maxwell’s equation. Selected application examples and solutions of these equations and their properties are discussed. "

Speaker: Thomas Flisgen (Ferdinand-Braun-Institut)

Flisgen_Theory_of_EM_Fields.pdf

Flisgen_Theory_of_EM_Fields.pptx

Recording

Video preview

10:30 Coffee break

4 RF measurements I

"The measurement of radio-frequency (RF) signals and the characterization of RF components, systems and subsystems used in particle accelerators is based on particular measurement instruments, like the RF vector network analyzer (VNA) and the spectrum analyzer (SA), but also on general-purpose instruments, like the oscilloscope and others. Before going into some details of SAs and VNAs, the concept of travelling waves in transmission lines is explained, along with their characteristics and the definition of the complex reflection coefficient. The Smith chart is introduced as a visualization tool, combining the complex impedance or admittance plane with the complex reflection coefficient in an elegant way. Some background on network theory is given to introduce the scattering (S)-parameters, again with a few examples. A few examples of measuring the characteristics of a simple cylindrical ("pillbox") resonator, i.e., resonance frequency, loaded and unloaded Q-value, and the R/Q geometric factor based on the perturbation bead-pull method, are covered. The last example explains the measurement of the longitudinal beam-coupling impedance of a vacuum device using the S21 stretched-wire method. Many other RF measurements were given in the practical hands-on afternoon sessions, like the characterization of travelling wave accelerator structures, noise figure measurements, characterization of non-linear devices (e.g., 1dB compression point, IP3 of RF amplifiers), AM and FM modulation, material characterization with resonators and waveguides, LLRF feedback systems, etc. could not be covered in this brief introduction.
"

Speaker: Manfred Wendt (CERN)

Recording

RFmeasurementsCAS2023.pdf

RFmeasurementsCAS2023.pptx

Video preview

Documentation

• CAS2023.pdf
• CAS2023_RF_Hands_on_Experiments.pdf
• CAS2023_Theory_wCover.pdf
• Hands-on_RFmeasurementsTeaser.pdf
• Hands-on_RFmeasurementsTeaser.pptx
• Overview_hands_on.pdf
• Overview_hands_on.pptx

5 Theory of EM fields II

"
In the presentation, theoretical foundations of electromagnetic fields are reviewed. First, general terms and concepts of field theory are discussed (scalar fields, vector fields, normal and tangential fields, dot product, cross product etc.) and then Maxwell’s equations in the integral form and material equations are recapitulated. It is shown how Maxwell’s equations in the integral form are transferred to the differential form by considering infinitely small Gaussian volumes and area elements. In this context, various vector operators are repeated and their properties are discussed. Based on the properties of these vector operators, conservation principles such as conservation of charges and conservation of energy are derived and interpreted. In the second part of the talk, field problems described by Maxwell’s equations are classified into electro-static, magneto-static and full-wave solutions. Poisson equation for electric potentials, Poisson equation for magnetic vector potentials, curl-curl equation and wave equation as well as Helmholtz equation in 2D and 3D are derived from Maxwell’s equation. Selected application examples and solutions of these equations and their properties are discussed. "

Speaker: Thomas Flisgen (Ferdinand-Braun-Institut)

Recording

Video preview

13:00 Lunch

6 RF material measurements

"S.Rudys, V.Kalendra, S.Svirskas, S.Balciunas, R.Grigalaitis, S.Lapinskas, J.Banys
Faculty of Physics, Vilnius University, Vilnius, Lithuania
web site: http://www.lms.ff.vu.lt
The dielectric response of materials provides information about the orientational adjustment of dipoles and the translational adjustment of mobile charges present in a dielectric medium in response to an applied electric field. Microwave and terahertz dielectric spectroscopy of ferroelectrics and related materials enables the independent determination of the dielectric permittivity and loss in the dispersion region, as well as the parameters of the soft modes related to phase transitions. Besides scientific purposes, microwave dielectric measurements are of increasing importance in telecommunications-related applications and the design of microwave circuit components. These applications include imaging radars, guidance systems, surveillance and secure communications. The magnetic properties are also of crucial importance. Dielectric and magnetic parameters fully characterize the manner in which electromagnetic waves propagate within the medium. The difficulties of making measurements on a wide range of materials over a wide frequency (and temperature) range have led to the development of various direct and indirect methods. At microwave frequencies, the direct single-frequency methods were enriched in the recent years with more convenient broad band frequency domain dielectric spectroscopy (FDDS), time – domain spectroscopy (TDS), Fourier transform spectroscopy (FTS). Computer controlled spectrometers are now the norm in dielectric spectroscopy. Computers allow the computation of electromagnetic fields in entirely new measurement geometries and the use of numerical analysis in the direct measurement process. The use of such spectrometers is now one of the most fruitful factors in new approaches to microwave dielectric spectroscopy. Each investigator employs the method adequate for the size and shape of a sample. The most important problem now is the rigorous mathematical solution of the microwave interaction with the samples in various geometries. Although there is now complete overlap and coverage of the radio frequency to the infrared band, the different experimental methods based on coaxial, waveguide, and resonator and free–space technique are still divided and will be presented. Examples of various ferroelectric, relaxor and other materials dielectric spectroscopy results will be presented."

Speaker: Mr Juras Banys

Banys_berlin 2023.ppt

Banys_berlin 2023.ppt

Recording

Video preview

7 Introduction Afternoon courses

Speakers: Alexandre Lasheen (CERN), Christine Vollinger (CERN), Frank Tecker (CERN), Manfred Wendt (CERN), Simon Albright (CERN)

Hands-on-groups-by-day.pdf

Hands-on-groups.pdf

Hands-on-Intro.pdf

Hands-on-Intro.pptx

Overview_hands_on_CST.pdf

Overview_hands_on_CST.pptx

Longitudinal Tracking

• 0_cheat_sheet.html
• 0_cheat_sheet.pdf
• 0_Foreword.html
• 0_Foreword.pdf
• 0_Installation_instructions.html
• 0_PythonExample.ipynb
• 1_Introduction.html
• 1_Introduction_optionA_corrected.ipynb
• 1_Introduction_optionA_empty.ipynb
• 1_Introduction_optionB_corrected.ipynb
• 1_Introduction_optionB_empty.ipynb
• 1_Introduction.pdf
• 2_Advanced.html
• 2_Advanced.pdf
• 2_AdvancedTracking_corrected.ipynb
• 2_AdvancedTracking_empty.ipynb
• all_files.tar.gz
• all_files.zip
• all_in_one_tracker.py
• PythonExampleFunctions.py
• support_functions.py

16:30 Coffee break

8 One slide - one minute

1S1M-Conor-Jenkins.pdf

1S1M-Conor-Jenkins.pptx

1S1M.pptx

18:00 Welcome Drink

19:30 Dinner

Tuesday 20 June

9 Overview cavities I

RF cavities are not only used to accelerate particle beams but they also kick beams or manipulate particles in the longitudinal phase space. They are used in linear and circular machines, some must have adjustable frequencies and some even accommodate multiple harmonics. Their operational use stretches from sub-per-mil duty cycles to continuous operation, they provide accelerating gradients from a few kilo Volts up to 100 million volts per metre using frequencies from a few Million Hertz up to 10s of Gigahertz. Depending on the specific use case their design and the used materials may be very different but they can all be classified using a well-established set of RF cavity characteristics. This lecture will derive these basic quantities from Maxwell’s equations and give examples of various cavity types. Furthermore, the description of an RF cavity via lumped circuit parameters will be introduced.

Speaker: Frank Gerigk (CERN)

Recording

RF-Cavities-F-Gerigk part 1.pdf

Video preview

10 EM simulations I

In the presentation foundations of electromagnetic simulations are recapitulated. Initially, the need for numerical methods used in electromagnetic simulations is motivated. Then, spatial discretization is discussed in a general way. This will be followed by a detailed introduction to the finite-integration technique, which allows to transfer of Maxwell’s equations into their discrete counterpart, namely Maxwell’s grid equations. Complementary to that, foundations on the spatial discretization using finite-element methods are provided, which are based on a weak formulation of the field problem. Based on these introductions, time domain computations are revisited in general and in particular for the finite-integration technique using the leap-frog approach. Complementary, frequency domain approaches are discussed in a very general fashion. In this context, the advantages of iterative methods over direct methods to solve large (sparse) linear systems of equations are highlighted. Special attention is devoted to the computation of network matrices (i.e. scattering matrices) of structures with large quality factors as this topic is highly relevant for RF for accelerators. This leads to a very short introduction of model order reduction methods and fast-frequency sweeps. The talk closes with some remarks on the finite-integration technique, the finite-element method and challenges arising when setting up new simulation models. Finally, recommendations on how to carefully validate and assess the results delivered by simulations are given. "

Speaker: Thomas Flisgen (Ferdinand-Braun-Institut)

Flisgen_EM_Simulations.pdf

Flisgen_EM_Simulations.pptx

Recording

Video preview

10:30 Coffee break

11 RF measurements II

The measurement of radio-frequency (RF) signals and the characterization of RF components, systems and subsystems used in particle accelerators is based on particular measurement instruments, like the RF vector network analyzer (VNA) and the spectrum analyzer (SA), but also on general-purpose instruments, like the oscilloscope and others. Before going into some details of SAs and VNAs, the concept of travelling waves in transmission lines is explained, along with their characteristics and the definition of the complex reflection coefficient. The Smith chart is introduced as a visualization tool, combining the complex impedance or admittance plane with the complex reflection coefficient in an elegant way. Some background on network theory is given to introduce the scattering (S)-parameters, again with a few examples. A few examples of measuring the characteristics of a simple cylindrical ("pillbox") resonator, i.e., resonance frequency, loaded and unloaded Q-value, and the R/Q geometric factor based on the perturbation bead-pull method, are covered. The last example explains the measurement of the longitudinal beam-coupling impedance of a vacuum device using the S21 stretched-wire method. Many other RF measurements were given in the practical hands-on afternoon sessions, like the characterization of travelling wave accelerator structures, noise figure measurements, characterization of non-linear devices (e.g., 1dB compression point, IP3 of RF amplifiers), AM and FM modulation, material characterization with resonators and waveguides, LLRF feedback systems, etc. could not be covered in this brief introduction.

Speaker: Manfred Wendt (CERN)

Recording

RFmeasurementsCAS2023_onlyPart2.pdf

RFmeasurementsCAS2023_onlyPart2.pptx

Video preview

CST_AxelPICexamples Pillbox.cst Pillbox_PIC.cst

CST_ButtonPickup

• button_pickup_params.txt
• ButtonPickUp_PIC_beta_sweep.cst
• ButtonPickUp_PIC.cst
• ButtonPickUp_TD.cst
• ButtonPickUp_Wakefield.cst

CST_FD Pillbox_FD.cst

CST_ManfredExamples

• cavity_eigen.cst
• cavity_EM.cst
• Cavity_Mat_eigen.cst
• coax_TD.cst
• MatResonator_EM.cst
• MyCavity.cst
• pillbox_EM.cst
• pillbox_emtest.cst
• PipewPlunger_WF.cst
• TE011cavity.cst
• test.cst
• wake.cst
• WakeImp.cst

CST_modelling

• ButtonPickUp.cst
• Pillbox.cst
• TESLA.cst

CST_PICmulitpacting Pillbox_EM_Hex.cst Pillbox_PIC.cst

Qucs

• CavityTM010res.dat
• CavityTM010res.dpl
• CavityTM010res.sch
• LPproto.sch
• resonator.dat
• resonator.dpl
• resonator.sch

12 EM simulations II

"
In the presentation foundations of electromagnetic simulations are recapitulated. Initially, the need for numerical methods used in electromagnetic simulations is motivated. Then, spatial discretization is discussed in a general way. This will be followed by a detailed introduction to the finite-integration technique, which allows to transfer Maxwell’s equations into their discrete counterpart, namely Maxwell’s grid equations. Complementary to that, foundations on the spatial discretization using finite-element methods are provided, which are based on a weak formulation of the field problem. Based on these introductions, time domain computations are revisited in general and in particular for the finite-integration technique using the leap-frog approach. Complementary, frequency domain approaches are discussed in a very general fashion. In this context, the advantages of iterative methods over direct methods to solve large (sparse) linear systems of equations are highlighted. Special attention is devoted to the computation of network matrices (i.e. scattering matrices) of structures with large quality factors as this topic is highly relevant for RF for accelerators. This leads to a very short introduction of model order reduction methods and fast-frequency sweeps. The talk closes with some remarks on the finite-integration technique, the finite-element method and on challenges arising when setting up new simulation models. Finally, recommendations on how to carefully validate and assess the results delivered by simulations are given. "

Speaker: Thomas Flisgen (Ferdinand-Braun-Institut)

Recording

Video preview

13:00 Lunch

13 Hands-on - Block I

16:30 Coffee break

14 Hands-on - Block I

15 EM simulations with CST

This Presentation will give a short intro in the numerical simulation of electromagnetic fields.
The pro and cons of various numerical solvers are discussed. Main focus of the presentation is the live demo of the modelling and optimisation of a WR90 Waveguide to Coax coupler. Advanced solver settings such as sensitivity analysis e.g. are demonstrate. The presentation is aimed to prepare the audience for the Hands-On session on CST Studio Suite during the CERN Accelerator School

Speaker: Dr Frank Demming-Janssen

Recording

Video preview

19:30 Dinner

Wednesday 21 June

16 RF power generation I

We reviewed the main types of RF power amplifiers used for particle accelerators.
It covers vacuum beam tubes, specifically gridded tubes, including tetrodes, inductive output tubes, klystrons, and transistor amplifiers, with power outputs greater than 10 kW CW or 100 kW pulsed at frequencies from 50 MHz to 1 GHz.
Functioning principle and construction aspects of these various items were presented.
Factors affecting the satisfactory operation of amplifiers, including cooling, matching, and protection circuits, were discussed.
The presentation concludes with a summary on the topic of efficiency.

Speaker: Eric Montesinos (CERN)

Recording

RF for Accelerators - RF power generation.pdf

RF for Accelerators - RF power generation.pptx

Video preview

17 Overview cavities II

RF cavities are not only used to accelerate particle beams but they also kick beams or manipulate particles in the longitudinal phase space. They are used in linear and circular machines, some must have adjustable frequencies and some even accommodate multiple harmonics. Their operational use stretches from sub-per-mil duty cycles to continuous operation, they provide accelerating gradients from a few kilo Volts up to 100 million volts per metre using frequencies from a few Million Hertz up to 10s of Gigahertz. Depending on the specific use case their design and the used materials may be very different but they can all be classified using a well-established set of RF cavity characteristics. This lecture will derive these basic quantities from Maxwell’s equations and give examples of various cavity types. Furthermore, the description of an RF cavity via lumped circuit parameters will be introduced.

Speaker: Frank Gerigk (CERN)

Recording

RF-Cavities-F-Gerigk part 2.pdf

Video preview

10:30 Coffee break

18 RF power generation II

We reviewed the main types of RF power amplifiers used for particle accelerators.
It covers vacuum beam tubes, specifically gridded tubes, including tetrodes, inductive output tubes, klystrons, and transistor amplifiers, with power outputs greater than 10 kW CW or 100 kW pulsed at frequencies from 50 MHz to 1 GHz.
Functioning principle and construction aspects of these various items were presented.
Factors affecting the satisfactory operation of amplifiers, including cooling, matching, and protection circuits, were discussed.
The presentation concludes with a summary on the topic of efficiency.

Speaker: Eric Montesinos (CERN)

Recording

RF for Accelerators - RF power generation.pdf

RF for Accelerators - RF power generation.pptx

Video preview

19 Longitudinal beam dynamics I

This talk gives a first introduction of longitudinal beam dynamics for both linear and circular accelerators.
It covers the basic methods of acceleration in a linac. For radio-frequency (RF) acceleration, it introduces the concepts of synchronicity and the oscillation around the synchronous particle, including the criterium for stability of the oscillations.
For circular accelerators, the cyclotron is explained, then the lecture focuses more on synchrotrons, their operation principle and their longitudinal beam dynamics. It reviews the synchrotron oscillations, their stability conditions and their representation in longitudinal phase space.

Speaker: Frank Tecker (CERN)

Longitudinal-Berlin-RF-2023.pdf

Longitudinal-Berlin-RF-2023.pptx

Recording

Video preview

13:00 Lunch

20 Hands-on - Block I

16:30 Coffee break

21 Hands-on - Block I

22 Quantum Entanglement - Spooky Action at a Distance

19:30 Dinner

Thursday 22 June

23 Basics of RF Electronics I

The focus for this educational text is selected examples of high-frequency electronic circuits and their components employed for the accurate phasing and synchronisation of accelerator cavities. Examples have been chosen to describe the basics of RF electronics. The starting point is transmission lines, connectors, discontinuities and the handling of reflection. The application of simple surface mount components is discussed. The first example presented is a circuit designed to synchronise the CLIC crab cavities. This example employs a co-planar waveguide, SMA connectors, Wilkinson splitters, and surface-mount double-balanced mixers. For the control of cavity phase and amplitude, the benefit of I&Q controllers will be explained. The text will then discuss the operation and use of a few more important components including I&Q modulators, ADCs, VCOs and optical fibre intensity modulators.

Speaker: Amos Dexter (Lancaster University)

Basics of RF Electronics Dexter Lecture 1 +correction.pdf

Basics of RF Electronics Dexter Lecture 1 +correction.pptx

Recording

Video preview

24 RF Power Transport

We reviewed the techniques of transport of high-power radiofrequency power from a RF power source to the cavities of an accelerator.
Waveguide and coaxial lines are explained showing power limits.
Main power couplers are also explained, on the construction side of it.

Speaker: Eric Montesinos (CERN)

Recording

RF for Accelerators - RF power transport.pdf

RF for Accelerators - RF power transport.pptx

Video preview

10:30 Coffee break

25 Basics of RF Electronics II

The focus of this educational text is selected examples of high-frequency electronic circuits and their components employed for the accurate phasing and synchronisation of accelerator cavities. Examples have been chosen to describe the basics of RF electronics. The starting point is transmission lines, connectors, discontinuities and the handling of reflection. The application of simple surface mount components is discussed. The first example presented is a circuit designed to synchronise the CLIC crab cavities. This example employs a co-planar waveguide, SMA connectors, Wilkinson splitters, and surface-mount double-balanced mixers. For the control of cavity phase and amplitude, the benefit of I&Q controllers will be explained. The text will then discuss the operation and use of a few more important components including I&Q modulators, ADCs, VCOs and optical fibre intensity modulators.

Speaker: Amos Dexter (Lancaster University)

Basics of RF Electronics Dexter Lecture 2.pdf

Basics of RF Electronics Dexter Lecture 2.pptx

Recording

Video preview

26 Low beta cavities

The contribution is on issues being especially related to normal conducting cavities operating at non-relativistic beam energies. Various types of cavities are introduced w.r.t. their operation mode, application, pros, and cons. Special emphasis is put on their production and the challenges along the way from finalised RF design up to the operating cavity. This covers the choice of material, production, tolerances, alignment, cooling, and the demanding task of copper plating. The contribution closes with some remarks on RF commissioning and –conditioning.

Speaker: Lars Groening (GSI Darmstadt)

NC_Cavities.pdf

Recording

Video preview

13:00 Lunch

14:30 Free / HZB Visit (optional)

19:30 Dinner

Friday 23 June

27 Beam Tracking I

The lectures treat longitudinal beam tracking in synchrotrons. After introducing the basics of creating an accelerator model and discretisation, the lecture discusses the choice of the time frame and coordinates for longitudinal tracking. Concerning tracking without intensity effects, it touches on symplectic, periodic boundary conditions, and RF gymnastics. Concerning collective effects, the course details how to include and discretise induced voltage in simulations and how to choose simulation parameters to well resolve beam and impedance. It briefly describes beam instabilities, multi-turn wakes, and synchrotron radiation. Thereafter, RF modelling is treated, including cavity-beam-transmitter interaction, phase and frequency modulation, as well as modelling global and local control loops. Then, the lecture walks through the generation of particle distributions and mentions some six-dimensional effects. Finally, code optimisation and benchmarking are treated, touching on code-design aspects, good practises runtime and memory considerations, as well as how to test, compare, and benchmark simulation code.

Speaker: Helga Timko (CERN)

Recording

RF_CAS_2023_Timko.key

RF_CAS_2023_Timko.pdf

Video preview

28 THz and optical acceleration techniques

We discuss recent progress in Terahertz and optical radiation generation and its use in acceleration and beam manipulation. The advantage of using short wavelength radiation is overcoming breakdown phenomena, enabling high gradient accelerators with lower bunch charge. Early results on guns, beam manipulation devices and accelerator structures are discussed.

Speaker: Franz Kaertner (Deutsches Elektronen-Synchrotron)

Recording

THz-Optical-Acc_Kärtner.pdf

THz-Optical-Acc_Kärtner.pptx

Video preview

10:30 Coffee break

29 Beam Tracking II

The lectures treat longitudinal beam tracking in synchrotrons. After introducing the basics of creating an accelerator model and discretisation, the lecture discusses the choice of the time frame and coordinates for longitudinal tracking. Concerning tracking without intensity effects, it touches on symplectic, periodic boundary conditions, and RF gymnastics. Concerning collective effects, the course details how to include and discretise induced voltage in simulations and how to choose simulation parameters to well resolve beam and impedance. It briefly describes beam instabilities, multi-turn wakes, and synchrotron radiation. Thereafter, RF modelling is treated, including cavity-beam-transmitter interaction, phase and frequency modulation, as well as modelling global and local control loops. Then, the lecture walks through the generation of particle distributions and mentions some six-dimensional effects. Finally, code optimisation and benchmarking are treated, touching on code-design aspects, good practises runtime and memory considerations, as well as how to test, compare, and benchmark simulation code.

Speaker: Helga Timko (CERN)

Recording

Video preview

30 SC cavities I

The lectures covers design, engineering, fabrication, testing and operation of superconducting systems for particle accelerator.
The main focus of this lecture is to cover the technological aspects of SRF Superconductivity.
Part I starts with explaining the benefits offered by RF superconductivity, and the conditions required for the operation in this regime, introducing the temperature choice and the thermodynamics aspect. The rest of this part introduces the design process of an accelerating cavity, in terms of RF, mechanical and cryogenic aspects. Limiting factors of SRF cavities are described, together with the processes needed to guarantee the needed performances. Cavity fabrication and preparation processes are reviewed, highlighting the need to avoid RF surface contamination to the maximum extent. Finally, the ancillaries needed for operation (couplers & tuners) are briefly introduced.
Part II concentrates of the environment needed for the SRF cavity operation, i.e. the accelerator cryomodule. Basic thermodynamics concepts and refrigeration processes are reviewed and the cryomodule design process illustrated, focusing on heat loss management practices.
Part III is finally dedicated to the performance characterization and operational aspects of superconducting RF cryomodules.

Speaker: Paolo Pierini

CAS SRF Tech Part I V0.pdf

CAS SRF Tech Part I V0.pptx

Recording

Video preview

13:00 Lunch

31 Hands-on - Block II

16:30 Coffee break

32 Hands-on - Block II

18:00 Poster Session

19:30 Dinner

Saturday 24 June

33 SC cavities II

The lectures cover the design, engineering, fabrication, testing and operation of superconducting systems for particle accelerators.
The main focus of this lecture is to cover the technological aspects of SRF Superconductivity.
Part I starts with explaining the benefits offered by RF superconductivity, and the conditions required for the operation in this regime, introducing the temperature choice and the thermodynamics aspect. The rest of this part introduces the design process of an accelerating cavity, in terms of RF, mechanical and cryogenic aspects. Limiting factors of SRF cavities are described, together with the processes needed to guarantee the needed performances. Cavity fabrication and preparation processes are reviewed, highlighting the need to avoid RF surface contamination to the maximum extent. Finally, the ancillaries needed for operation (couplers & tuners) are briefly introduced.
Part II concentrates the environment needed for the SRF cavity operation, i.e. the accelerator cryomodule. Basic thermodynamics concepts and refrigeration processes are reviewed and the cryomodule design process is illustrated, focusing on heat loss management practices.
Part III is finally dedicated to the performance characterization and operational aspects of superconducting RF cryomodules.

Speaker: Paolo Pierini

CAS SRF Tech Part II V0.pdf

CAS SRF Tech Part II V0.pptx

Recording

Video preview

34 Magnetic alloy / ferrite cavities

"RF cavities loaded with magnetic alloy (MA) or ferrite ring cores are used in synchrotrons and storage rings if the maximum RF frequency is in the order of a few MHz. A simple model for the description of cavities of this type is derived. The most important parameters are defined, and some properties of the material and of the cavity are summarised.
Different cavity configurations, development aspects, and several practical topics are discussed. A few specific ferrites- and MA-loaded cavity systems are presented as examples."

Speaker: Harald Klingbeil (TU Darmstadt and GSI)

CAS_RF_MA_and_Ferrite_Cavities_i.pdf

CAS_RF_MA_and_Ferrite_Cavities_i.pptx

Recording

Video preview

10:30 Coffee break

35 SC cavities III

The lectures cover the design, engineering, fabrication, testing and operation of superconducting systems for particle accelerators.
The main focus of this lecture is to cover the technological aspects of SRF Superconductivity.
Part I starts with explaining the benefits offered by RF superconductivity, and the conditions required for the operation in this regime, introducing the temperature choice and the thermodynamics aspect. The rest of this part introduces the design process of an accelerating cavity, in terms of RF, mechanical and cryogenic aspects. Limiting factors of SRF cavities are described, together with the processes needed to guarantee the needed performances. Cavity fabrication and preparation processes are reviewed, highlighting the need to avoid RF surface contamination to the maximum extent. Finally, the ancillaries needed for operation (couplers & tuners) are briefly introduced.
Part II concentrates the environment needed for the SRF cavity operation, i.e. the accelerator cryomodule. Basic thermodynamics concepts and refrigeration processes are reviewed and the cryomodule design process is illustrated, focusing on heat loss management practices.
Part III is finally dedicated to the performance characterization and operational aspects of superconducting RF cryomodules.

Speaker: Paolo Pierini

CAS SRF Tech Part III V0.pdf

CAS SRF Tech Part III V0.pptx

Recording

Video preview

36 Discussion

13:00 Lunch

37 Hands-on - Block II

16:30 Coffee break

38 Hands-on - Block II

19:30 Dinner

Sunday 25 June

09:00 Excursion: 4-hour boat trip (10h00-14h00) with lunch

19:30 Dinner

Monday 26 June

39 LLRF I

Modern particle accelerators use electromagnetic energy at RF frequencies to accelerate particles. This course outlines the fundamental concepts needed to understand the monitoring and control of electromagnetic fields. Often this area of study is called “Low-Level RF”. The course is aimed at non-electrical engineers with little experience in RF. The course is designed to illustrate frequency domain system design concepts necessary for understanding RF control systems for particle accelerators. The lecture begins with an overview of spectrum analysis, an introduction of control theory, and some examples of LLRF topics.

Speaker: David McGennis

llrf.pdf

Recording

Video preview

40 Impedances and wakefields

The lecture reviews general concepts of beam-induced electromagnetic fields in accelerator devices. The concept of momentum kick is introduced and thus wake function and wake potential. The case of single-particle Green function as well as the bunch case are treated, giving the definition of the typically used quantities to describe such effects. Coupling impedance is introduced as Fourier Transform of the wake function, relevant to describe such interactions in ring accelerators. Examples are given from working machines as well as novel ones, presently under design, e.g. emittance limited storage rings and Future Circular Colliders. The lecture concludes by presenting possible applications of wakefields in particle accelerations.

Speaker: Prof. Andrea Mostacci (Sapienza University of Rome e INFN-Roma I (IT))

Recording

Video preview

WakeFiedls_Impedance_out.pdf

WakeFiedls_Impedance_out.pptx

10:30 Coffee break

41 Beam Loading

Radio-frequency (RF) systems in particle accelerators are usually designed to transfer energy to the beam or to define its longitudinal structure. However, charged particles passing through an RF cavity induce a voltage which acts back on themselves and on subsequent particles. The additional contribution of the beam to the cavity voltage moreover changes the effective properties of the RF system and is generally referred to as beam loading. The fundamental theorem of beam loading is introduced to derive the effect of a single bunch passage through an RF cavity. The choice of the cavity parameters, notably shunt impedance divided by quality factor, plays an important role to reduce the beam induced voltage. Extending the single bunch case to the periodic passage of bunches allows to calculate the steady state cavity detuning due to beam loading for a continuous bunch pattern. Special emphasis is given to the partially filled ring, with gaps in the filling pattern, which is the most common case of transient beam loading in electron and hadron synchrotrons.

Speaker: Heiko Damerau (CERN)

BeamLoading.pdf

BeamLoading.pptx

Recording

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42 RF Beam Diagnostics I

The lecture reviews general concepts of diagnostics for beam intensity diagnostics, beam transverse position and bunch length as well as beam arrival. Such concepts are discussed with some examples. Concerning the beam intensity, current transformers and passive cavity are presented by showing the working principle and the main properties. Strip-lines and cavity beam position monitors have been selected to show the main issues of position measurements.
Concerning the bunch length measurement, the case of RF deflectors for bunch length
measurement in high brightness LINAC is carefully described. The lecture shows the measurement principle as well as the design, realization and operation of a standing wave cavity; examples of beam measurements are given as well.

Speaker: Prof. Andrea Mostacci (Sapienza University of Rome e INFN-Roma I (IT))

Recording

RF_beam_Diagnostics_p1_out_corrected.pdf

RF_beam_Diagnostics_p1_out_corrected.pptx

Video preview

13:00 Lunch

43 Hands-on - Block III

16:30 Coffee break

44 Hands-on - Block III

19:30 Dinner

Tuesday 27 June

45 RF Beam Diagnostics II

The lecture reviews general concepts of diagnostics for beam intensity diagnostics, beam transverse position and bunch length as well as beam arrival. Such concepts are discussed with some examples. Concerning the beam intensity, current transformers and passive cavity are presented by showing the working principle and the main properties. Strip-lines and cavity beam position monitors have been selected to show the main issues of position measurements.
Concerning the bunch length measurement, the case of RF deflectors for bunch length
measurement in high brightness LINAC is carefully described. The lecture shows the measurement principle as well as the design, realization and operation of a standing wave cavity; examples of beam measurements are given as well.

Speaker: Prof. Andrea Mostacci (Sapienza University of Rome e INFN-Roma I (IT))

RF_beam_Diagnostics_p2_out.pdf

RF_beam_Diagnostics_p2_out.pptx

46 LLRF II

Modern particle accelerators use electromagnetic energy at RF frequencies to accelerate particles. This course outlines the fundamental concepts needed to understand the monitoring and control of electromagnetic fields. Often this area of study is called “Low-Level RF”. The course is aimed at non-electrical engineers with little experience in RF. The course is designed to illustrate frequency domain system design concepts necessary for understanding RF control systems for particle accelerators. The lecture begins with an overview of spectrum analysis, an introduction of control theory, and some examples of LLRF topics.

Speaker: David McGinnis

Recording

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10:30 Coffee break

47 Longitudinal beam dynamics II

In the first part of the lecture, the main characteristics of synchrotron motion, namely, synchronous particle and phase, bucket area and emittance are introduced. The equations of longitudinal particle motion in a single RF system of a proton synchrotron are re-derived and the phase equation is analysed for small and large amplitude particles. The particle motion below and above transition crossing is also considered.
The main applications and operation modes of a double RF system are discussed in the second part of the lecture.

Speaker: Elena Shaposhnikova

CAS_RF_Shaposhnikova.pdf

CAS_RF_Shaposhnikova.pptx

Recording

Video preview

48 LLRF III

Modern particle accelerators use electromagnetic energy at RF frequencies to accelerate particles. This course outlines the fundamental concepts needed to understand the monitoring and control of electromagnetic fields. Often this area of study is called “Low-Level RF”. The course is aimed at non-electrical engineers with little experience in RF. The course is designed to illustrate frequency domain system design concepts necessary for understanding RF control systems for particle accelerators. The lecture begins with an overview of spectrum analysis, an introduction of control theory, and some examples of LLRF topics.

Speaker: David McGinnis

Recording

Video preview

13:00 Lunch

49 Hands-on - Block III

16:30 Coffee break

50 Hands-on - Block III

19:30 Dinner

21:00 Social event

Wednesday 28 June

08:30 Free / HZB Visit (optional)

13:00 Lunch

51 Hands-on - Block IV

16:30 Coffee break

52 Hands-on - Block IV

19:30 Dinner

Thursday 29 June

53 Power Coupling + Matching

In order to maximise the power delivered to the cavity we must minimise reflections. Reflections are minimised when the source and load impedances are equal, however this is difficult when the cavity impedance is orders of magnitude higher than the source. A power coupler acts like a transformer changing the cavity impedance “seen” by the source allowing matching. This lecture looks at what impedance matching means, how to match RF cavities, transient filling behaviour of cavities, power requirements for real cavities with beam, and matching travelling wave structures.

Speaker: Graeme Burt

CAS Coupling.pdf

CAS Coupling.pptx

Recording

Video preview

54 Longitudinal instabilities & Intensity effects

In this lecture, dealing with intensity effects, the equations of motion with induced beam voltage are analysed.
This allows, first, to describe single-bunch potential well distortion and loss of Landau damping. Then the linearised Vlasov equation is used to derive step-by-step the Lebedev equation. This matrix equation is applied to find the thresholds, growth rates and spectra of unstable multi-bunch beam. The lecture is concluded by discussion of possible beam-instability cures.

Speaker: Elena Shaposhnikova

CAS_RF_Shaposhnikova_v1.pdf

CAS_RF_Shaposhnikova_v1.pptx

Recording

Video preview

10:30 Coffee break

55 RF manipulations I

Beyond increasing the energy of charged particles, RF frequency systems in accelerators allow to control longitudinal beam properties like distance between the bunches, their length, position in time, as well as the orbit length in a synchrotron. This is essential to adapt the beam parameters to the requirements of experiments or downstream accelerators. Already with a single-harmonic RF system a variety of manipulations to bunch or de-bunch a beam and to control the bunch length can be performed. More flexibility is reached with multiple RF systems, often at different harmonic numbers of the revolution frequency. For example, a change of harmonic number to merge or split bunches, respectively doubles, or halves the intensity per bunch. A sequential increase of the RF harmonic can also be applied to reduce bunch spacing. Even more evolved RF manipulations become possible with non-sinusoidal RF systems driving wide-band RF cavities, gaining almost full control of the longitudinal beam structure. Special attention is moreover paid to the technical implementation of RF manipulations, complemented by examples of applications in major accelerator facilities.

Speaker: Heiko Damerau (CERN)

Recording

RFManipulationsBothParts.pdf

RFManipulationsBothParts.pptx

Video preview

56 High beta cativies I

The lectures “High-Beta Cavities I and II” cover the main concepts that underly acceleration of relativistic beams, with a focus on traveling wave acceleration. These include the concepts of phase velocity and synchronism with the beam, group velocity, periodically loaded accelerating structures, the Brillouin diagram and the fundamental theorem of beam loading derived from an energy balance point of view.

Speaker: Walter Wuensch (CERN)

Recording

rf cas wuensch lecture 1 final.pdf

rf cas wuensch lecture 1 final.pptx

Video preview

13:00 Lunch

57 Hands-on - Block IV

16:30 Coffee break

58 Hands-on - Block IV

19:30 Dinner

Friday 30 June

59 RF manipulations II

Beyond increasing the energy of charged particles, RF frequency systems in accelerators allow to control longitudinal beam properties like distance between the bunches, their length, position in time, as well as the orbit length in a synchrotron. This is essential to adapt the beam parameters to the requirements of experiments or downstream accelerators. Already with a single-harmonic RF system a variety of manipulations to bunch or de-bunch a beam and to control the bunch length can be performed. More flexibility is reached with multiple RF systems, often at different harmonic numbers of the revolution frequency. For example, a change of harmonic number to merge or split bunches, respectively doubles, or halves the intensity per bunch. A sequential increase of the RF harmonic can also be applied to reduce bunch spacing. Even more evolved RF manipulations become possible with non-sinusoidal RF systems driving wide-band RF cavities, gaining almost full control of the longitudinal beam structure. Special attention is moreover paid to the technical implementation of RF manipulations, complemented by examples of applications in major accelerator facilities.

Speaker: Heiko Damerau (CERN)

Recording

RFManipulationsBothParts.pdf

RFManipulationsBothParts.pptx

Video preview

60 Transverse deflecting cavities

Many applications require RF cavities that deflect the beam transversely, where the field needs to vary faster than can be achieved using magnets. This lecture studies dipole modes used for these applications and uses Panofsky-Wenzel theorem to look at transverse voltages, beam loading and mode requirements. The lecture also looks at modern TE and TEM deflecting mode cavities as well as several examples of deflecting or crabbing cavities.

Speaker: Graeme Burt

CAS Deflecting.pdf

CAS Deflecting.pptx

Recording

Video preview

10:30 Coffee break

61 High beta cavities II

The lectures “High-Beta Cavities I and II” cover the main concepts that underly acceleration of relativistic beams, with a focus on traveling wave acceleration. These include the concepts of phase velocity and synchronism with the beam, group velocity, periodically loaded accelerating structures, the Brillouin diagram and the fundamental theorem of beam loading derived from an energy balance point of view.

Speaker: Walter Wuensch (CERN)

Recording

rf cas wuensch lecture 2 final2.pdf

rf cas wuensch lecture 2 final2.pptx

Video preview

62 HOM mitigation

Higher Order Modes (HOM) in accelerating structures are resonant electromagnetic fields excited and left behind by charged particle bunches. They can dramatically degrade the beam quality in accelerators, such as the multi-bunch energy spread and transverse emittance and therefore, one has to study and make them harmless carefully. In this lecture, various methods of HOM mitigation are reviewed. On one hand, one tries to avoid their existence, for example, by careful design of the accelerating structures and damping systems. On the other hand, one can reduce the effect of the excited HOM fields, for example, by means of fast feedback or beam alignment. Also, a few ways to make HOM signals useful are referred to, such as beam diagnostics or accelerating structures.

Speaker: Nicoleta Baboi (DESY)

2023.06_CAS-RFforAccelerators_HOMmitigation.pdf

2023.06_CAS-RFforAccelerators_HOMmitigation.pptx

Recording

Video preview

13:00 Lunch

63 Multipacting Breakdowns

The lecture “Multipactor and Breakdown” gives an introduction into the two main arcing phenomena encountered in high-power RF systems. The basic resonant character of multipactor and the role of secondary electron yield is shown. For vacuum breakdown, the lecture introduces how this is often observed in high-power systems followed by an overview of the main physical processes the lead up to the arc and determine its evolution.

Speaker: Walter Wuensch (CERN)

Recording

rf cas wuensch lecture 3 final.pptx

Video preview

64 Discussion

16:30 Coffee break

65 Closing

Speaker: Frank Tecker (CERN)

closing-rf-2023.pdf

closing-rf-2023.pptx

19:30 Special Dinner

Saturday 1 July

66 Departure day