FIELD: surface-ionization ion sources. ^ SUBSTANCE: device can be used in drift spectrometer and other analytical devices. Surface of electrode which control ion current from surface of flat thermal emitter, having working surface of D diameter, turned to ion thermal emitter, has ring-shaped protrusion. Diameter of external base of protrusion coincides with diameter of working surface of thermal emitter, and diameter of internal base coincides with diameter d of central channel in electrode controlling thermal emitter's ion current. The most optimal version of ion source has to be ion source into which source the diameter D3 of vertex of ring-shaped onto surface of electrode for controlling ion current is chosen from relation of D3=(0,8-1,2)*(D+d)/2. Height of protrusion is chosen from relation of h1=(0,4-0,6)*h and meaning h of space between surface of thermal emitter and flat part of electrode controlling thermal emitter's current, is chosen from relation of h=(0,4-1,5)*d. High efficiency of ion collection
