The talk will cover operation and operational aspects of megawatt CW tetrode amplifiers, summarizing the following topics:
- What are the typical faults and problems and their impact on availability.
- What do we need to do as preventive maintenance to reduce the down time in operation.
- What is the level of remote diagnostics and how much we can "fix remotely".
- What is a typical...
In the framework of the low emittance high brilliance Elettra 2.0 project four 130 kW continuous way 500 MHz Solid State Amplifiers (SSA) have been installed and commissioned. These SSAs are already used for the RF plants in operation at Elettra having replaced the aged klystron and IOT based amplifiers. The Elettra user up time has improved since their placing in service providing a...
Operation of the Spallation Neutron Source (SNS) RF Systems provide a broad study of high-power equipment and sources including solid state amplifiers, tetrodes, klystrons, waveguide circulators and fundamental power couplers. While not unique to the SNS, over 20 years of operating at high average and peak powers have yielded insights to overcoming technical problems of interest to the wider...
The RF systems for the first phase for the European Spallation Source accelerator is nearing completion. A total of 91 high power systems will be installed to support an average power capability of a 2 MW beam on target. ESS is a long-pulse machine which will operate at 14 Hz, with 2.86 ms pulses. Commissioning to a low power dump is expected to start early 2025 ahead of commissioning to the...
The klystron based RF systems for the APS storage ring were recently modified to support the MBA based lattice of APS-U. This involved both the high and low power components of the RF systems. Discussed are the some technical details, challenges faced, and the lessons learnt.
The Spallation Neutron Source at Oak Ridge National Laboratory utilizes a dual RF system for H⁻ beam generation, where a continuous wave (CW) 300-450 W 13 MHz RF initiates a low-density plasma that is subsequently enhanced by a pulsed 60 kW 2 MHz RF to achieve high-density plasma. Recently, we have tested a new pulsed 50-150 W 27 MHz RF on the Ion Source Test Stand to replace the CW 13 MHz RF,...
R&K, an independent company, has achieved production of 2.3 million 1.9GHz microwave power amplifiers for mobile-comm’s-base-stations and then also supplies wideband power amplifiers for automobile EMC testing for domestic automobile industries. Then 16 years ago, we started designing and producing some hundreds kW RF SSA for accelerator applications as alternatives to Klystron / tube.
The...
A programmable signal processor-based credited safety control that calculates pulsed beam power based on beam kinetic energy and charge was designed as part of the Proton Power Upgrade (PPU) project at the Spallation Neutron Source (SNS). The system must reliably shut off the beam if the average power exceeds 2.145 MW averaging over 60 seconds. This paper discusses the calibration of the...
The Spallation Neutron Source (SNS) is implementing camera-based systems to enhance the reliability of high-power RF vacuum windows in its Drift Tube Linac (DTL) and Coupled Cavity Linac (CCL) sections. In the DTL, a high-speed camera will detect electron glow discharges sometimes associated with multipacting, a critical issue leading to window damage. This effort is part of a broader project...
In the spring of 2021 NSLS-II commissioned the project’s first SSA high power transmitter (310 kW CW) to complement the two existing 310 kW klystron-based transmitters which had been in use since 2012. This presentation will present the technical performance of the system as well as detail the hardware and software failures that occurred and the resulting downtime accumulated over the past...
Taiwan Photon Source (TPS) is a 3 GeV third-generation light source operating at a storage current of 500 mA. It currently operates with two RF stations, each capable of providing 300 kW of RF power. In the original design, each RF station employed a 500 MHz klystron-type RF transmitter. In August 2023, we switched one of the klystron-type RF transmitters to a 500 MHz home-made solid-state...
A new radiofrequency (rf) driver amplifier is being designed to replace 3 kW rf amplifiers that are part of the 197 MHz rf system in the Relativistic Heavy Ion Collider (RHIC) located at Brookhaven National Laboratory. A prototype was built using a gallium nitride device able to operate up to 100 V on the drain side. First measurements indicate that a single unit can generate power in excess...
Los Alamos Neutron Science Center uses a coupled-cavity linac (CCL) to accelerate H- beam from 100 to 800 MeV. This was the first CCL put into operation (1972) and is powered by forty-four 1.25 MW 805 MHz klystrons developed in the same era. Replacement klystrons have had mortality rates higher than tubes made over 25 years ago. This has caused us to embark on a new initiative to develop a...
The Advanced Photon Source (APS) user facility began operation by delivering first x-ray on March 26, 1995. Over the many years, the RF Group maintains and improves four different types of rf powers systems. One system consists of a high-power pulsed klystron within the Linear Accelerator (LINAC), two different types of rf power systems within the Positron Accumulator Ring (PAR), and a Booster...
The transition from klystrons to solid state rf power sources at the Advanced Photon Source is well underway, with the first four 352MHz/160kW solid state rf systems scheduled for installation in the fall of 2025. R&D efforts leading up to the transition to solid state will be discussed, including the design and testing of 352MHz prototype solid state rf amplifiers at the 12kW, 32kW, and...
The commissioning of klystron systems for the first phase of the European Spallation Source with an average power capability of a 2MW beam on target is complete. More than 70 site acceptance tests of high power pulsed klystrons have been carried out over the last years. This talk will describe some of the difficulties experienced during on-site testing and the technical solutions developed and...
Ion Cyclotron Range of Frequencies (ICRF) have been demonstrated in reactor-grade plasmas to be effective at plasma heating and central current drive, which are necessary to initiate and maintain controlled fusion reactions. For high magnetic field fusion devices 60-240 MHz systems are envisioned, which are ideal for solid state devices.
Diversified Technologies, Inc. (DTI) is building a...
The Continuous Electron Beam Accelerator Facility (CEBAF) at Jefferson Lab was upgraded to 12 GeV in 2014, necessitating the use of high-power klystrons. The C75 and C100 cryomodules, which enable the 12 GeV operation, are capable of achieving higher gradients and are powered by 8 kW and 13 kW klystrons, respectively. Over the past decade of operating at 12 GeV, we have observed a decline in...
The conditioning of RF components and their proper storage are crucial for stable and reliable Linear Accelerator (LINAC) operation. The Radio-Frequency Test Facility (RFTF) was built to test the RF subsystems and to condition the RF windows and couplers of the LINACs at the Spallation Neutron Source (SNS). It consists of two waveguide systems operating at 402.5 MHz and 805 MHz, powered by...
High power RF transmission line supplied by Microwave Techniques LLC (MT), formerly MEGA Industries, can be found in nearly every high-power microwave application around the world. Through the acquisition of Ferrite Microwave Technologies (FMT), MT engineers have had the opportunity to focus on circulator technology and compensation methodology. It is well understood that the low loss ferrite...
All high power, klystron based, RF systems at ESS rely on high power loads and circulators to protect the klystrons from excessive reflected power and to enable full power testing of the full amplifier chains. The high power testing of the system have revealed significant technical issues with the load design, resulting in damage and poor performance. We report on the high power investigations...
Power variators (PV) or variable attenuators are required to control the RF power transfer to accelerator cavities and to realize dual energy LINACs operated at Megawatt peak power. Dual energy LINACs are used in medical radiation therapy (dual photon energy and imaging mode), as well as in industrial X-ray inspection systems for enhanced material detection in cargo scanning and...
The reliability of Los Alamos Neutron Science Center (LANSCE) 805MHz klystrons used for powering the CCL will be examined and data presented on service hours, post re-build performance and failure points. Reliability and performance of today’s klystrons will be compared with historical data and our current evaluation process will be discussed. Foreseeable problems with current capabilities...
Two units of 500 MHz 60 kW CW AR RF High Power Amplifiers (HPA) has been designed and manufactured as per LBNL's Engg Specifications & Requirements Document through a joint effort between engineers at LBNL and engineers at vendor R&K Company Ltd, Japan. The HPA design documents were reviewed by LBNL and also desk reviewed by NRTL company UL to USA standards prior to conducting the Final Design...
FRIB is commissioning a 120 kW, 80.5 MHz solid-state RF amplifier for the RFQ cavity to increase overall system availability. Although reliability of the tetrode amplifier was greatly improved during commissioning and early operations, some potential failures may have long repair times. In contrast, solid-state amplifiers have shorter repair time due to the modular design and no high...
The RF system for the Alternating Gradient Synchrotron (AGS) at Brookhaven National Lab (BNL) consists of a Tetrode Based Power Amplifier (PA) driven by a Solid-State Feedback Amplifier (SSFB). Due to the nature of the tetrode, the Screen Voltage is prone to arcing to the Grid. This creates a transient at the Screen Voltage (2kV) which appears on the output of the SSFB damaging the devices....
To support the reliable operation, there have been three RFQs developed at SNS. SNS RFQs are 4-vane type structures designed to accelerate H- beam from 65 keV to 2.5 MeV with estimated transmission efficiency above 90%. The RFQ02 was installed to the SNS Front End and started operating for beam production in 2018. After a few years of operation, field tilts were observed in all four quadrants...
Fermilab’s PIP-II project seeks to enhance its proton beam capabilities for scientific research by modifying the existing synchrotrons and replacing the linear accelerator with a superconducting linear accelerator. To mitigate risks in technology readiness and prepare for operational maintenance, test stands of various complexities were built. Many of the RF components, subsystems, and systems...
