THERMO-ELECTRIC FIELD EMISSION ELECTRON GUN

摘要

PURPOSE:To provide a stable electron beam with good reproducibility in a short time by forming a suppresser electrode from either titanium whose hydrogen content is not greater than a predetermined amount or an alloy composed chiefly of titanium. CONSTITUTION:A tungsten single crystal needle 1 having a (100) axial orientation and provided with a cover layer made of zirconium and oxygen is welded to tungsten filaments 2 used for supporting and heating. The filaments 2 are welded also to metallic columns 4 passed through an insulator 5 and held in place. A suppresser electrode 3 properly adjusts the projected length of the needle 1 and is secured to the insulator 5 by the tightening of a holding screw 6 provided on the side of the electrode 3. The electrode 3 is made of either titanium with a hydrogen content of 60ppm or less, or an alloy composed chiefly of titanium.