The ISE 5 utilises proven cold cathode principals for operation. Argon gas is fed into the gas cell that acts as the cold cathode ion source and a voltage is applied between the anode and cathode to initiate and sustain the gas discharge. The longitudinal magnetic field through the source region causes any electrons generated in the discharge to have a spiral path (and an extended path length) in the discharge which enables them to cause large ion and electron generation.
The ions are extracted from the gas cell through an aperture in the cathode plate and into a flight tube. In the flight tube the ions are travelling with high energy but are only at the final beam energy once they have left the source. This feature enables the source to maintain an acceptable target current at low beam energies.
The focus element in the flight tube enables the ion beam to be focused onto the sample. For normal operation gas is fed into the source continuously via a leak valve providing a pressure differential between the gas supply and the ion source. The magnetic field enables the discharge to be generated at relatively low pressures in the gas cell section of the ISE 5.