EFFECTS OF APPLIED MAGNETIC-FIELDS ON PERFORMANCE OF A QUASI-STEADY MAGNETOPLASMADYNAMIC ARCJET

A quasisteady magnetoplasmadynamic arcjet with applied magnetic fields was studied to clarify the influence of axial magnetic fields on the thruster performance and the discharge feature. Pulsed axial magnetic fields were applied by a few-turn coil, which was connected with a pul se-forming network independent of the main discharge circuit. An incre ase in axial-field intensity raised the discharge voltages at constant discharge currents below the limiting current with H-2, the mixture o f N-2 + 2H(2) simulating fully decomposed hydrazine, and Ar. The thrus t characteristics for H-2 and the mixture of N-2 + 2H(2) showed that t here was the optimum axial-field intensity with which the maximum thru st was achieved for each gas, although at low discharge current levels for H-2 and Ar the thrusts increased a with axial-field intensity. Th e discharges for all gases were inclined to occur more upstream with a n increase in axial-field intensity. It was inferred that these effect s of axial magnetic fields on the thruster performance and the arc fea ture were due to the rotating motion of -J(r) x B-z, i.e., swirl accel eration and enhanced thermalization.