THE EFFECT OF A MAGNETIC-FIELD GRADIENT ON ANODE DOUBLE-LAYERS

In experiments on anode (ionization) double layers in nonuniform magne tic fields it has been noted that the magnetic field gradient seems to stabilize the double layer position. This effect is further investiga ted in a Q machine in which the magnetic field geometry could be varie d. We find that the position of the double layers, along the axis of t he device, could be controlled by changing the magnetic geometry. We a ccount for this effect in a physical model which takes into account th e effect of ion reflection by the magnetic mirror force in the region of magnetic field nonuniformity. This model is also able to account fo r variation of the double layer position when the neutral gas pressure is varied.