Oblique electron-beam injection into plasma: Effect of external magnetic field upon gun environment

When injecting an electron beam,vith a significant pitch-angle In a magneto plasma, one has to take care that the par allel velocity of the electrons m easured in the plasma does not only depend on the acceleration potential be tween the anode and the cathode of the electron gun, hut also on the amplit ude of the ambient magnetic field. The latter can play an important role wh en the actual acceleration distance of electrons in the gun vicinity, deter mined partly by collective processes that lead to potential modification in the gun environment, is large enough. Consequently, the actual beam pitch- angle can be noticeably different from the orientation of the electron gun.