A correlation method of the nonperturbative diagnostics of an ion beam

The nonperturbative diagnostics of an ion beam hy a method based on correla tion analysis is reviewed. The physical foundation of this method is the po ssibility of detecting an interaction between a negligible fi action of the ions and a probing internal target which produces secondary informative pa rticles, whose spectrum is virtually identical to the beam spectrum in the magnitude and the direction of velocity and which call be selectively detec ted without affecting the beam. By measuring the cross-correlation function between the fluxes of particles or photons of the probing target pseudoran domly modulated in time, and the informative particles that are produced on the target and are detected on a flight base, the time-of-flight spectrum (the energy distribution) of ions along a chosen direction is determined. A relative analysis of these functions for different positions of the target in the beam and different directions of detecting the informative particle s allows one to obtain the ion distribution in transverse phase space. The basic elements of the diagnostic instrument and capabilities of this instru ment are the nonperturbative correlation measurements of the parameters of a beam of negative (particularly the H- ion) or positive molecular ions, wh ich can undergo photodisintegration on the probing photon target. A target necessary for the diagnostics may be formed by using stochastically pulsed radiation of some solid-state lasers, such as Nd:YAG, in the free-generatio n mode.