What is “arcjet”? Here’s a google search… to get you started… 
I was asked to help out a co-worker who’s bombarded with work to work on this… Shuttle tiles are going through some major testing and NASA/JSC uses arcjet to create plasma (very high temperature gas with dissociated particles) and recreate entry conditions.
Arcjets work by sending high amp current through gas and the electrical energy increases the particles’ energy and gets accelerated through nozzles. I got to visit the JSC Arcjet Facility today and am quite excited! 10 MW (at max) ability! Wow… 