A COMPACT, RF-DRIVEN, PULSED ION SOURCE FOR INTENSE NEUTRON GENERATION*

Lawrence Berkeley National Laboratory is currently developing a compact, sealed-accelerator-tube neutron generator for activation analysis applications. This portable generator is projected to produce a neutron flux in the range of 109 to 1010 D-T neutrons per second. A 2 MHz radio-frequency (rf)-driven ion sources, designed to fit within a ~ 5 cm diameter borehole, is used. Typical operating parameters include repetition rates up to 100 pps, with pulse widths between 10 and 80 µs and source pressures as low as 4 mTorr. In this configuration, peak extractable hydrogen current exceeding 35 mA from a 2 mm diameter aperture, together with H1 yields over 94 % have been achieved. The required rf impedance matching network has been successfully miniaturized to ~ 5 cm diameter and tested. Given the low duty cycle operation, the ion source and matching do not require any cooling