Study of the plasma-material interaction during simulated plasma disruptions

1)Department of Space and Astronautical Science, SOKENDAI (The Graduate University for Advanced Studies), Sagamihara, Japan 2)Department of Aerospace Engineering, Nagoya University, Nagoya, Japan 3) Department of Aerospace Engineering, Nihon University, Funabashi, Japan 4)Aeronautical Technology Directorate, JAXA, Chofu, Japan 5)Institute of Space and Astronautical Science, JAXA, Sagamihara, Japan

The Effect of Anode Configuration on Hydrogen MPD Thruster Performance: A Numerical Study

The plasma plume of a 1-MW-class quasi-steady magnetoplasmadynamic (MPD) arcjet is studied to determine the plume structure and plasma plume fluctuations in a downstream plume region (250-1250 mm away from the MPD arcjet). By using a double probe and a high-electron-temperature ( ~ 5 eV) and high-number-density (~8 ×1019 m-3) region, so-called “cathode jets” are found along the central axis of plasma plume close to the MPD arcjet. Moreover, the plasma plume radial profile is constant in a downstream plume region (≥ 750 mm from the MPD arcjet). The power spectrum density (PSD) of the ion saturation current is proportional to 1/f1.6 (f: frequency) for f >; 80 kHz, and in this frequency range, PSD decreased with distance from the MPD arcjet. In contrast, in the frequency region <; 80 kHz, the PSD-f curve is at a constant value. Although a peak in the discharge voltage is attributed to the generalized lower hybrid drift instability (GLHDI), this instability is not found in the plasma plume near the MPD arcjet. The influence of the GLHDI is limited only to the discharge chamber, and fluctuations caused by the instability are random in the downstream region.

Plume Characteristics of a Quasi-Steady Magnetoplasmadynamic Arcjet

Feature of Exhaust Plasma Flows for a Quasi-Steady MPD Thruster

Numerical Study on Discharge Current Path and Performance of a Magnetoplasmadynamic Thruster

Experimental researches on the operational performance and the arc structure of a quasisteady magnetoplasmadynamic (MPD) arcjet was made to develop a high-performanceaccelerator in space. The results showed that the current pattern, which depended strongly on gas species and discharge current levels, influenced the thruster performance. It was found that the plasma produced in the discharge chamber was compressed radially and that 50% on the input power was consumed in the cathode region. From the plasma potential distribution, a positive voltage slope and mass starvation were found to be present near the anode surface beyond the predicted critical current level.

Takahisa Sakakibara

Papers

Operational characteristics and discharge mechanisms of quasisteady magnetoplasmadynamic(MPD) arcjet for space propulsion.