Design and operating characteristics of new type cold cathode ion source

Abstract

In this work, the design and performance of new type ion source are described. The discharge mechanism of the source is based on creating an arc discharge through a saddle electric field inside the discharge tube. The saddle electric field is created by immersing an annular anode inside the discharge tube covered from the upper and lower ends with two flanges. These two flanges act as cathodes. The discharge tube is surrounded by a solenoid coil which produces an axial magnetic field (up to 400 G) measured at the center of the source. Measurements have been performed to find out the influence of arc power, pressure, discharge voltage, magnetic field, and extracting voltage on the ion source properties. The source yields an argon ion current of approximately 0.6 mA and electron current of approximately 4 mA at normal operating conditions (extraction voltage V(ex)=7 kV, pressure of 5.5x10(-4) Torr, V(arc)=400 V, I(arc)=1 A, B=200 G). It showed an energy spread of 20 eV at a discharge voltage of 400 V and an extraction voltage of 3 kV.