Abstract: An emitter produces a beam of electrons or ions accelerated at a relatively high accelerating voltage. The beam is sharply focused by a condenser lens at the final stage. An electrostatic field for retarding the beam is produced between the lens at the final stage and a target on which the beam impinges. The retarding field lowers the landing energy of the beam. An auxiliary electrode which is maintained at substantially the same potential as the target is disposed between the lens and the target. A secondary electron detector is mounted between the auxiliary electrode and the target.

Abstract: A reservoir containing a material to be ionized has in its bottom a capillary extending outwardly in symmetrical with the optical axis of an ion source, and has a needle extending coaxially through said capillary in said reservoir so that the apex end of the needle projects slightly beyond the exterior surface of the reservoir. Intensive electric field at the apex end of the needle is formed by an extracting electrode disposed in facing the needle. An electric current is supplied through conductive wires or filaments supporting the reservoir for heating the reservoir. As a result, the liquid material to be ionized in the reservoir seeps smoothly through the capillary of the reservoir toward the apex end of the needle for field evaporation and ionization.

Abstract: An electron gun comprising a changeover chamber and changeover circuit between the gun chamber and the insulated cable which connects the power supply circuits to the electrodes which enables adjustment of electrode potentials to accomplish electrode treatment without excessive gun currents.