Characteristics of Cold-Electrode Emitter Materials for Pulsed Hollow Cathode Discharges

Hollow cathode discharges have long been used for many applications such as light sources for spectroscopic studies, pumping sources for gas lasers and high-power plasma switching applications. For plasma switches, the initiation of the plasma is critical and this is usually achieved by a "trigger" scheme. This work presents the initial studies on the role of cold-cathode material to be used as the "trigger electrode" to initiate the ionization processes. Once the candidate materials are identified, the experimental setup will consist of a simple hollow-cathode / hollow-anode geometry with a trigger electrode placed behind the cathode to provide the initial seed electrons to initiate the hollow cathode discharge. The primary objective of this work is to find possible materials with higher cold-electron emission characteristics in higher pressure rages than the traditional operating pressures of pseudospark switches. The SEM and electron emission characteristics of two trigger electrode materials namely carbon nano-tubes and zinc oxide are presented.