Study of the influence of the injection section on the stability of a high-current relativistic electron beam propagating through the gaseous medium of a plasmochemical reactor

Results are presented from experimental study of the influence of the injection section on the stability of a high-current relativistic electron beam (REB) propagating through the gaseous medium of a plasmochemical reactor (PR). An REB with the electron energy E e =1 MeV, beam current I b =10–22 kA, and pulse duration t=60 ns was generated by the Tonus accelerator and, then, injected into a 0.1-m-diameter PR filled with air. The PR consisted of two sections with lengths L 1= 0.3–1.0 m and L 2=1.1–2.5 m; the total length of the system was no longer than 3.5 m. The first section was filled with air at a pressure of P 1=0.8–1.5 torr, and the pressure in the second section was varied within the range P 2=0.1–760 torr. The current I b of an REB passed through both sections of the PR was measured with the help of a sectioned vacuum Faraday cup. The transportation efficiency of the beam was determined as the ratio I b /I inj, where I inj is the beam current measured at the point of injection into the PR. It is shown that, for the optimal dimensions of the first PR section, it has a stabilizing action on the REB with a current density of up to 3 kA/cm2, which makes it possible to increase the effective length of the second (working) PR section, which is filled with a gas at various pressures, to L 2=(25–35)L bet, where L bet is the beam betatron length.