Damage To Injector Component Surfaces during Local Helicity Injection in Pegasus-III

Abstract Pegasus III uses hollow-cathode arc plasma sources inside an injector assemblies to create electron beams to study tokamak plasma initiation via local helicity injection. These injector assemblies are exposed to intense power and particle fluxes from plasma material interactions that cause damage to injector components, limiting the injector lifetime. New injectors require surface conditioning to operate without sourcing current from the electrode surfaces and damaging the electrodes. Initial studies comparing surfaces of new molybdenum injector components to those at the end of their lifetime have been performed and found that significant melting is observed on electrode components most directly exposed to the injected plasma, while components exposed to the main chamber plasma show evidence of blistering.