Optimization of the Lanthanum Hexaboride (LaB6) Cathode for Divertor Plasma Simulator (DiPS)

Abstract

A new versatile linear machine, called DiPS (Divertor Plasma Simulator) has been developed for the divertor edge simulation, space propulsion and electric probe technology and its applications. To verify and develop theories of electric probes with magnetic field, collisionality, various particle source, and wide range of plasma parameters, one needs a plasma source with the following plasma parameters: density=10^6 - 10^14 cm^-3, electron temperature = 1-10eV, magnetic field = 0-2kG, plasma types = RF and DC. For these conditions, the DiPS is developed with two plasma sources, LaB6 (DC) and Helicon plasma (RF). The LaB6 cathode used in DiPS consists of disk-type LaB6 which is indirectly heated by the graphite heater up to 5 kW. The discharge voltage and current are 1-100 V and 1-50 A, respectively. The Helicon plasma source is also developed as a high density rf plasma source in DiPS, which generates the high density plasma with the of power of 0-3kW by using m=0 antenna. The Optimization procedure of the LaB6 cathode is presented with the discharge parameters such as the discharge current, discharge voltage and the operating pressure.