The 4X Source

Our Penning surface-plasma source (SPS) discharge chamber was enlarged 4X in two dimensions. To date, three pulsed discharge modes have been studied: two with noisy arc (#x02273;20% H- current fluctuations) and one with quiescent arc (≲1% H- current fluctuations). Lower arc magnetic field and higher H2 gas flow allow switching from the noisy to the quiescent mode. The noisy modes yield up to 120 mA of 29-keV H- beam; for 110 mA at 29 keV, the two-dimensional normalized rms emittance is 0.017 x 0.018 π·cm·mrad. The quiescent mode yields 75 mA of 29-keV H- beam; for 67 mA at 24 keV, the emittance is 0.011 x 0.012 π·cm·mrad.