Crossed E×B-Fields Back-Bombardment Instability and Ion Cyclotron Heating of Gas-Discharge Plasma Streams

The article present our recent results of computer simulations and theory analysis concerning of dynamics of the crossed E×B-fields back-bombardment (BKB) instability in magnetron diodes. The concept of the BKB-instability applied to show new explanation for known experimental data of an intense ion heating in accelerated plasma streams. Main features of the BKB-instability into ion diodes are following: 1) ion magnetic insulation is d₀ > r_i where d₀ is accelerating gap across applied magnetic field B₀, r_i = 5V₀^0.5/B₀ is proton Larmor radius, cm; V₀ – applied voltage, kV; B₀ – kG; 2) E_A ≠ 0 is high electric field on self or secondary emission anode electrodes; 3) main frequency oscillation of f_s = f_ci/2 = 0.76 B₀ MHz; 4) convert power efficiency of η_B = P_~/P₀ is up to 50%.

Radial proton HF-oscillations current density of the J_ir provided by the BKB-instability excites magnetohydrodynamics waves. They are propagated in the tube plasma with azimuthal velocity v_∼9 ~ 10⁷ cm/s (M_iv_∼9² ~ eV₀) and along the B₀ with the v_A ~ 4×10⁷ cm/s -Alfven velocity. Known experimental data was demonstrated a level of the HF-oscillation power which was absorbed by proton streams by ion cyclotron heating equals up to 30% total supply power of the 1 MW.

Work supported by RFFI under grant 96-02-19215.