Conveners
Modelling and simulations: Arc and plasma dynamics
- Matthew Hopkins (Sandia National Laboratories)
Modelling and simulations: Breakdown Models
- Chris Moore (Sandia National Labs)
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Loanne Monnin09/03/2021, 14:00Oral
The increase of the onboarded power on Spacecraft is actually still limited by the charging issue due to the plasma natural environment. The charging of the external dielectrics is due to the complex geometry, the number of different materials and the presence of biased conductor. It leads to a high potential difference on solar cells edges that can reach several kilo-volts. In this...
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Dr Helena T. C. Kaufmann (University of Madeira)09/03/2021, 14:30Oral
Vacuum breakdown in the pulsed DC experiment at CERN was investigated by means of electrical measurements, SEM and STEM imaging of the surface and cross sections of the copper electrodes, and numerical modeling. The breakdown sites comprise one or more craters. There is plastic deformation beneath the craters.
The crater(s) represent the epicenter of the breakdown, where electron emission...
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Dan Wang09/03/2021, 15:00Oral
In this work, a two-dimensional (2D) particle-in-cell/Monte Carlo collisional (PIC/MCC) model is developed to simulate the plasma decay and re-breakdown in the post-arc stage of vacuum circuit breakers. The field distribution is obtained by solving the Poisson’s equation in 2D cylindrical coordinate and the positions of charged particles, which are traced as super particles to save the...
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Mr Lee Millar (Lancaster University (GB))12/03/2021, 15:45Oral
High-voltage accelerating structures (and other vacuum devices) are limited by the occurrence of vacuum arcs. To operate reliably such components must be subjected to a conditioning process in which the operating voltage is slowly increased over time while monitoring for arcs. This process is performed at great temporal and monetary expense, typically requiring millions of RF pulses or several...
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Tommaso Patton (Consorzio RFX)12/03/2021, 16:15Oral
The Voltage Holding Prediction Model (VHPM) is a design technique formulated at Consorzio RFX that combines numerical modelling and experimental data in order to calculate a breakdown probability curve. The cuve is based on the two parameters Weibull distribution for any multi-electrode multi-voltage vacuum insulated system under dc voltage. The progresses in employing the VHPM to predict the...
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Ye Wang12/03/2021, 16:45Oral
Metal cathodes have inevitable surface defects, such as dust, protrusions or small-scale roughness caused by manufacturing. Under high electric field, these defects will generate local electric field enhancement, that can help to initiate vacuum breakdown. When in large, the classical vacuum breakdown mechanism has already been clarified, it demonstrates that small protrusions could be...
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Jim Norem (Argonne Labs (retired))12/03/2021, 17:15Oral
Almost 120 years after the isolation of vacuum arcs, the exact mechanisms of the arcs and the damage they produce are still being debated. We describe our simple and general model of the vacuum arc that can incorporate all active mechanisms and aims to explain all relevant data. Our four stage model, is based on experiments done at 805 MHz with a variety of cavity geometries, magnetic fields,...
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