A 25-KeV, 30-milliamp hydrogen-ion injector for A 200-MHz, 750-KeV radiofrequency quadrupole

An injector development program is being pursued at Linac systems for satisfying linear accelerator input beam requirements. Proton beams with 25-keV beam energy and 30-mA current with variable duty factors are presently being produced. The two main injector ingredients are a microwave plasma source and a single - einzel lens for matching the proton beam into the radio frequency quadrupole (RFQ) accelerator. By realistic design simulation, the 25-keV rms normalized emittance is predicted to be 0.07 (pimm-mrad) after extraction from the plasma. The proton beam rms normalized emittance is predicted to grow to 0.24 (pimm-mrad) at the RFQ match point for 26 mA proton current. Insertion of a LEBT beam scraper reduces the predicted proton beam current to 15 mA with 0.085 (pimm-mrad) rms normalized emittance. A proton beam with these characteristics is predicted to have good transmission through the 4-bar, 200-MHz RFQ. Recent injector-RFQ measurements are confirming these design predictions, with 18-mA RFQ output current recently measured.