Conceptual Design of Diagnostic Hydrogen Beam Injector for TRT Tokamak

A conceptual design of a charge-exchange hydrogen atomic beam diagnostic injector for the TRT tokamak is presented. The injector is supposed to be used to measure the plasma parameters in the tokamak by active spectroscopy methods. In an ion source of the diagnostic injector, a ballistically focused ion beam is formed by a precision multi-aperture ion–optical system with four spherical electrodes. The plasma emitter is created by the hydrogen plasma from an arc generator or from a generator with an inductive RF discharge, expanding into a volume with a peripheral multipole magnetic field. The equivalent current of a beam of hydrogen atoms with an energy of 60 keV injected into the TRT plasma is ~4.5 A. At an angular beam divergence of ~7 mrad and a distance of ~9 m from the ion source to the center of the tokamak plasma, the diameter of the diagnostic beam in the measurement zone is ~13 cm at the level of 1/e. During the operating pulse of the TRT tokamak, several modulated pulses of the diagnostic beam of hydrogen atoms can be injected with a duration of ~1 s.