“…A plasma cathode does not rely on a thermionic emissive material and, instead, relies on ionization and electron generation in the bulk plasma [11]. Depending on the type of discharge, plasma cathodes can be grouped in radio frequency (RF) cathodes, capacitively coupled plasma (CCP) [12] and inductively couple plasma (ICP) [13], [14], microwave cathodes [15], [16], electron cyclotron resonance (ECR) cathodes [17], helicon cathodes [18], and direct current (DC) cathodes [19].…”