Performance of Intense Pulsed Ion Source

The development of intense pulsed plasma ion sources for high current extraction of He+, Ne+ and Xe+ beams is motivated by several applications. Cold (Ti < 0.2 eV) He+ ions extracted at current density of 1-1.5 A/cm2 across a 1 m radius surface for a total current of 25 kA in 0.5 ¿s pulses are required for a Light Ion Fusion Experiment (LIFE) ICF driver based on the neutralized and ballistically focused propagation approach. Moderate temperature (Ti ~, 3 eV) Ne+ and Xe+ ions at 1-1.5 A/cm2 for 1-10 A extracted currents in ms long pulses are required in several recent low ß approaches based on multi-aperture quadrupole focused RF acceleration schemes such as the MEQALAC and the RFQ injector. In a test ion source, plasma is induced by ms time pulsing a 0.3 MHz, 0.1 MW RF oscillator with power AC-coupled to an antenna situated inside a 30 cm radius cylindrical vessel where the interior surfaces are lined with cusp-field permanent magnets except for the front extraction face. The plasma parameters Te, Ti, np are characterized by measurements as a function of time during ms long pulses and in the immediate afterglow, the neutral gas density, the RF power and location at the extraction surface, and data are compared with derived scaling relations.