FIRST RESULTS OF A HIGH-CURRENT ELECTRON-CYCLOTRON-RESONANCE PROTON SOURCE

A 2.45 GHz electron cyclotron resonance (ECR) ion source for producing a 100 mA H+ beam is under study. The microwave power is coupled throu gh a quartz window and a water-cooled 90 degrees waveguide bend in ord er to avoid the heating of the electrons backstreaming from the source . The ECR condition is obtained with de magnetic coils. Preliminary re sults reported here show that a beam current density of 75 mA/cm(2) ca n be extracted at 10 kV from a 3-mm-diam aperture, with 1.2 kW of micr owave power at 1x10(-3) mbar of hydrogen pressure. The proton fraction is 75% with an alumina-coated plasma electrode and 85% with a nitride coating. (C) 1996 American Institute of Physics.