Lithium beam experiments at 425 kV

Experiments on the interactions of a Lithium ion beam with a dense hydrogen plasma channel will be discussed. The 550kV ion beam is generated by a magnetically insulated race track diode. Using a sequence of in situ anode heating and discharge cleaning a very pure (approximately 90%) Lithium beam is produced. This beam is passed through a set of apertures and an energy selector before it is injected into the plasma channel. The plasma channel is 71cm in length and is produced by discharging a 25kJ capacitor bank into a theta-pinch coil. The plasma density varies from 1-5 × 10¹⁶ cm^-3 as measured by a holographic interferometer and the plasma temperature is determined by spectroscopy to be around 20 eV. The exiting beam particles are analysed by a Thomson parabola to determine the ionization state of the Lithium. Of particular interest are the charge changing interactions whereby Li⁺ and Li⁺⁺ interact with plasma protons to become Li⁺⁺ and Li⁺⁺⁺.