Multipacting
Abstract
Multipacting (MP) is a resonant electron discharge, often plaguing radiofrequency structures, produced by the synchronization of emitted electrons with the RF fields and by the electron multiplication at the impact point with the surface of the structure. The current of reemitted electrons grows via true secondary reemission when the secondary yield for the primary electron impact energy is greater than one. A simple example (MP in shortgap accelerating axialsymmetric cavities) allows an analytical solution of the equation of motion, giving both the synchronization (kinematics) and multiplication (impact energy) conditions as a function of the gap voltage (or accelerating field). Starting from this example a thorough discussion of MP discharges in axialsymmetric accelerating structures will be given and some poor man's rules are given to estimate the critical cavity field levels to meet the kinematic condition for resonance. The results of these poor man's rules are compared with computer simulations of MP discharges obtained by a statistical analysis of the reemission yield for impinging electrons versus RF field level in the accelerating structure.
 Publication:

arXiv eprints
 Pub Date:
 December 2011
 arXiv:
 arXiv:1112.2176
 Bibcode:
 2011arXiv1112.2176P
 Keywords:

 Physics  Accelerator Physics
 EPrint:
 presented at the CERN Accelerator School CAS 2010: RF for accelerators, Ebeltoft, 817 June 2010