Pulsed hot cathode (LaB6) discharge for uniform plasma production

A pulsed hot cathode hydrogen discharge of several milliseconds duration is used to produce a dense (<1014 cm−3), uniform plasma target for atomic collision studies. This plasma, whose cross section is determined by the cathode shape, is rectangular, since it is produced by a discharge (1500 V, ∼100 A) from a 2×11-cm2 rectangular LaB6 slab cathode along a 0.1-T magnetic field to a gas-fed anode. Background hydrogen (∼1 Pa) and contaminant gas (<10−2 Pa) are kept low by injecting H2 during the discharge into an evacuated (∼10−4 Pa) chamber. One drawback of this discharge for atomic physics applications is that at high plasma density (ne >2×1013 cm−3), sufficient fluxes of >1-keV x rays are produced to flood our solid-state detectors with background counts.