Helical instability of a plasma filament with frozen faces

In experiments on plasma heating by a relativistic beam the beam passes through the plasma filament in a homogeneous magnetic field. It is well known that when noncompensated total current, being an algebraic sum of a beam current and a reverse current, exceeds some critical value, hydrodynamic helical instability starts developing in such a system. The effect of plasma filament frozen into face walls on screw instability development is studied. It is found that plasma filament frozen into the faces stabilizes the effect if it is in the conducting housing. The critical current value is determined. The nonlinear instability development stage under conditions of weak supercriticality is described. 2 refs.; 1 fig