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 singleeinzel 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

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... (πmm-mrad) after extraction from the plasma. The proton beam rms normalized emittance is predicted to grow to 0.24 (πmm-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 (πmm-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.