| Co-Investigator(Kenkyū-buntansha) |
TAHARA Hirokazu Osaka University, Faculty of Engineering Science. Research Associate, 基礎工学部, 助手 (20207210)
TSUBAKISHITA Yasuji Osaka University, Faculty of Engineering Science. Associate Professor, 基礎工学部, 助教授 (00116063)
ONOE Ken-ichi Osaka University, Faculty of Engineering Science. Reseach Associate, 基礎工学部, 助手 (70029429)
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| Research Abstract |
Quasisteady magnetoplasmadynamic thrusters with applied magnetic fields were studied to clarify the influence of axial magnetic fields on the thruster performance and the discharge feature and to understand the acceleration mechanism. The main power-supplying pulse forming network (PFN), which was capable of storing 62 KJ at 8 KV, delivered a single nonreversing quasisteady current of maximum 27 KA with a pulse width of 0.6 msec. A vacuum tank 5.75m in length and 0.6m in diameter, where the thruster fired, was evacuated to some 10^<-3> Pa prior to each discharge. Pulsed axial magnetic fields were applied by a few-turn coil, which was connected with a PFN independent of the main discharge circuit. An increase in axial field strength raised the discharge voltages at constant discharge currents below the limiting current with H_2, mixture of N_2+2H_2 and Ar. The thrust characteristics for H_2 and mixture of N_2+2H_2 showed that there was the optimum axial field strength with which the maximum thrust was achieved for each gas, although at low discharge current levels for H_2 and Ar the thrusts increased with axial field strength. The discharges for all gases were inclined to occur more upstream with an increase in axial field strength, resulting in broad high-temperature distributions in the discharge chamber. It was inferred that these effects of axial magnetic fields on the thruster performance and the arc feature were due to rotating motion of -J_rxB_z, that is, swirl acceleration and enhanced thermalization.
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