Last results of the continuous-wave high-intensity light ion source at CEA-Saclay

Abstract

The high-intensity light ion source (SILHI) is designed to be a prototype source for high power linear accelerators. The goal is to produce a 100 mA proton or a 140 mA deuteron ion beams at 95 keV with rms normalized emittance lower than 0.2 π mm mrad. A 108 mA total beam (J=215 mA/cm2) was extracted in April 1997 (85% H+, 12% H2+, and 3% H3+ fractions) with two electron cyclotron resonance (ECR) zones located at both plasma chamber extremities simultaneously. First beam measurements indicate a 0.17 π mm mrad rms normalized emittance for a 80 mA proton beam at 80 keV. In these conditions, a 96% availability was obtained during an 8 h working day. An intermediate electrode is placed in the accelerator gap to minimize emittance distortions as shown by simulations. Beam analysis were made as a function of the intermediate electrode voltage, the gas flow, the magnetic field, and the 2.45 GHz rf power. First rf plasma coupling observations indicated that the magnetron was too highly coupled with the load (plasma chamber). By adding a second circulator and locking the oscillator with an external signal, this dependence was decreased. Measurements then clearly show that the output spectrum is completely independent of the load phasing. All these results will be presented.