Cascaded arc plasma source

The cascaded arc is a wall-stabilized thermal arc discharge that produces high density, low temperature plasmas.

The cascaded arc source, developed at the Eindhoven University of Technology , is shown in the figure below. Compared to plasma sources in other linear plasma generators, this source can produce high-density argon and hydrogen plasmas (respectively $10^{21}-10^{24}$m$^{-3}$ and $10^{19}-10^{22}$ m$^{-3}$) at relatively low electron temperatures (~1 eV). Due to the high collision frequency of the particles in the source, the plasma is in thermal equilibrium and reasonable homogeneous.

The cascaded arc consists of a gas inlet, three tungsten cathodes, cascaded plates, a nozzle and an anode. Via the gas inlet, the working gas -argon or hydrogen- can flow into the cathode chamber. The source is typically running at 0.5 - 3.0 slm (1 standard litre per minute = 4.4 · $10^{20}$ particles per second) and a discharge current of 100-300 A. The cascaded plates in between the cathode and anode are electrically insulated from each other by 1 mm thick boron-nitride plates. The potential of these plates is floating. Both nozzle and anode are grounded.