Studies of Trapping and Accumulation of Fast Ions in Preliminary Experiments on Neutral Beam Injection at the GOL-NB Facility

The results are presented from preliminary experiments on neutral beam injection with the power of approximately 1 MW into the central trap of the GOL-NB facility. The main technical task of the work was the integrated commissioning of all systems and basic diagnostics. The results are presented on the attenuation of neutral beams in plasma and the parameters of the fast ion population. In the regimes under discussion, the attenuation factor of the flow of injected particles of heating beams reaches 40% at the simultaneous start of the initial plasma accumulation in the trap and its heating by neutral beams. The dynamics of accumulation and energy spectrum of the fast ion population formed in plasma as a result of neutral beam injection are discussed, and the physical mechanisms are analyzed that can provide for the observed spectrum of fast ions.