At the high-gradient X-band test facility at CERN, prototype accelerating structures for the Compact Linear Collider (CLIC) are tested at high powers of up to 50 MW to achieve accelerating gradients of over 100 MV/m and peak surface electric fields of over 220 MV/m, and are conditioned to reach the highest possible gradient at low breakdown rate. The setup of the test stands will be presented,...
We have been performing high-gradient tests of X-band (11.4 GHz) normal-conducting accelerating structures at a test facility called Nextef in KEK, aiming at operational accelerating gradients of 100 MV/m or higher. In this report, we present recent results of high-gradient tests on the test structures, including a quadrant-type waveguide-damped single-cell test cavity.
The voltage breakdown in the accelerator of Neutral Beam Injectors for Plasma Heating and Current Drive (H&CD) has a very frequent occurrence, due to the harsh environment of the accelerator. The beams formed by accelerated defocused ions and electrons escaped from magnetic traps hit the electrodes (e.g. the acceleration grids and the vessel) melting the surfaces with massive production of...
We are applying our understanding of vacuum arc mechanisms by attempting to mitigate coronal losses on high voltage transmission line conductors. These losses seem to involve field emission and occur at surface fields around 20 MV/m. The results of high-voltage tests on the corona discharge in the conditions of simulating the rain of samples of aluminum wire of grade AC 300/39 coated with...
Abstract - Since vacuum interrupter is a native AC current interruption device, new methods should be developed for DC current interruption. The objective of this work is to propose a DC current interruption method by applying a controllable rotating transverse magnetic field on vacuum arc. The experiment was conducted using an L-C-R discharge circuit, with the DC arc current ranged of 80-320...
