Conveners
Poster Session: Breakdown in RF structures & diamond
- Marek Jacewicz (Uppsala University (SE))
- Andreas Kyritsakis
Poster Session: Experiments & Diagnostics
- Walter Wuensch (CERN)
- Matthew Hopkins (Sandia National Laboratories)
Poster Session: Modelling and simulations
- Antonio De Lorenzi (Consorzio RFX, Associazione EURATOM-ENEA sulla Fusione, Padova, Italy)
- Anton Saressalo (Helsinki Institute of Physics (FI))
Poster Session: Field emission
- Yinon Ashkenazy (The Hebrew University of Jerusalem)
- Sergio Calatroni (CERN)
Spatially resolving electron emission from field emission cathode surface is a crucial step to characterize and quantify emission uniformity and emission area, and therefore, beam brightness and current density. It is especially important for mm-wave/terahertz sources for which narrow beam is a must, or for miniaturized field emission devices where high current density is required. It is also...
High voltage insulation across a single gap in vacuum and low-pressure gas is a critical issue in relation to the development and realization of the electrostatic accelerator for the ITER Neutral Beam Injector (NBI).
The present paper describes and analyzes the recent experimental results obtained at the High Voltage Padova Test Facility (HVPTF), the laboratory aimed at supporting the...
In a quest to identify low density materials for anode wires to be used in electrostatic septa for accelerator particle beam extraction, a basic test set-up was constructed at CERN. The set-up re-uses many components of the former LEAR electrostatic injection septum to limit the cost. As such, it inherits design features from the former septum, such as a displacement system for the anode and...
As field emission effects play critical role in the physics of breakdown, modelling these effects is a critical aspect to better understand and mitigate breakdown. Proposed here is an initial particle distribution generator called FEgen version 1 (based on the time dependent Fowler-Nordheim equation), a part of the FEmaster platform which is a comprehensive toolkit for field emission...
Vacuum arcs (breakdowns) limit operation in high-gradient accelerating structures and other high-voltage vacuum devices. To investigate the phenomenon a collaboration has been established at CERN to explore the application of machine learning in the CLIC (Compact Linear Collider) high-gradient test stands.
Currently, a machine learning framework has been developed to analyse the test stand...
As the ubiquity of field emission sources becomes more prevalent in that a variety of cathode materials and geometries are being tested or used, an easy-to-use data processing pipeline FEbeam was developed, and it is a part of the FEmaster platform [1-3]. This algorithm processes and converts raw data to the standard format enabling further physics interpretation: combining 17 different...
The advantages of the vacuum technology such as environmental compatibility and emission-free solutions make the vacuum interrupters attractive for switching applications in power grids. The lifetime of the contact system is mainly limited by accumulated thermal load of the electrode surface. Therefore, various measures are applied for the reduction of this load. Two types of electrode...
Atomic diffusion on metallic surfaces under electric field is known to be biased towards higher field values. In the vicinity of a field-enhancing protrusion, stochastically hopping surface atoms are hypothesized to contribute to the growth of the protrusion by this bias mechanism.
In the context of the Compact Linear Collider (CLIC), field-enhancer growth by diffusion is one of the...
The quantum-mechanical problem of the motion of electrons through a potential barrier with an additional near-surface dipole layer is considered. An analytical generalization of the Fowler-Nordheim formula, for such potential barriers, was made. Using such a model is a way to consider the influence of vacancies and pores existing in the surface layer of a metal on the field emission current...
An electron within a piece of condensed matter is held into the material by a surface barrier. In
simple basic models, the force preventing electron escape is attributed to an image attraction between
the electron and the material surface. This gives rise to an energy barrier of zero-field height H that
prevents classical escape. The application of a classical electrostatic field of...
We present a model for stochastic, micron-scale field emission for use in Particle-In-Cell Direct Simulation Monte Carlo (PIC-DSMC) simulations of vacuum discharge. PIC-DSMC simulations of mm-sized electrodes cannot resolve atomic-scale (nm) surface features and therefore we generate micron-scale probability density distributions for an effective “local” work function, field enhancement...
This Poster forms part of a quiet campaign by the author to bring the theory of field electron
emission (FE), as used in technological contexts, into a common form based on: (a) the "new" rules
for writing scientific equations introduced as part of the 1970s reforms associated with the
introduction of SI units; and (b) modern formulations [1,2] of the 1956 FE theory of Murphy and
Good (MG)...
In this work, we continue looking into polarization characteristics of surfaces in the presence of adatoms by means of density functional theory. We follow the changes of these characteristics during possible transitions of an adatom as an event of self-diffusion on the W{110} surface. We analyze the dependencies of these characteristics on the environment of the adatom when it jumps towards...
When metal surfaces are exposed to the hydrogen ion irradiation, light ions are expected to penetrate deep into the material and dissolve in the matrix. However, these atoms are seen to cause significant modification of surfaces indicating that they accumulate in vicinity of the surface. The process known as blistering may reduces the vacuum dielectric strength above the metal surface, which...
Plasma-wall interaction is one of the most critical factors determining plasma parameters in fusion devices. Plasma parameters, material properties, and morphology of plasma-facing components (PFCs) determine this interaction. PFCs must satisfy the needed requirements, such as operation under high thermal and particle irradiation. In the case of tungsten (W) PFC, its surface morphology may...
