Hammad Aftab

Plasma instabilities limit the efficiency of magnetic nozzle-based plasma thrusters, particularly in the low-power regime, which is critical for space missions with constrained power. We present a linear dispersion model for plasma thrusters with isothermal electrons and β-distributed ions, identifying an unstable axisymmetric (m = 0) compressional Alfvén wave. This mode is experimentally observed in a high-temperature superconducting applied-field MPD thruster, appearing in the 3–6 MHz range and driven by high-energy ions in the plume, which induce oscillations in the ion energy distribution and trigger the instability, degrading performance. Suppression of these ion fluctuations at 300 sccm effectively stabilizes the instability mode. As a result, the HTS-based MPD thruster achieves 35% efficiency at 14.6 kW, producing 390 mN of thrust with a specific impulse of 4471 s. These results demonstrate record performance for a sub-15 kW MPD thruster and provide a framework for identifying and controlling compressional Alfvénic instabilities in magnetically confined plasma systems.

The high temperature superconductors enhanced magnetoplasmadynamic thruster is a promising device for various space mission scenarios. However, a critical issue hindering the enhancement of the thruster’s performance is the problem of anode power deposition. Previous studies have identified the anode fall voltage as a major contributor to this power deposition. This paper introduces an approximate analytical formula for calculating anode power deposition resulting from anode fall voltage. The paper further analyzes and calculates the variation of anode fall voltage with an applied magnetic field and discharge current. The findings reveal a direct correlation between applied magnetic field and both anode fall voltage and power, indicating an increase with higher magnetic field values. In contrast, while the anode fall voltage experiences a slight decline with increased discharge current, the anode power deposition remains elevated due to the transition from field ionization to thermal ionization. To gain a comprehensive understanding of anode power deposition, an experiment was conducted to obtain measurements under different operating conditions, involving varying levels of applied magnetic field and discharge current. The experimental results align with the theoretical predictions. These insights have the potential to serve as a valuable reference for enhancing the efficiency of magnetoplasmadynamic thrusters, bringing us closer to unlocking the full potential of these remarkable propulsion systems in the realm of space exploration.

The neutrino beam driven instability of fast and slow magnetosonic waves with oblique applied magnetic field in multi-component ion, electron and neutrino beam plasma is studied. The dissipation effects of ion-neutral collisions are also included in the model. The neutrino and electron interactions through electro-weak force are included. It is found that the dissipation of ion collisions has significant effect on the phase velocity of the wave propagation and growth rate of the neutrino beam driven instability. The analytical expression of the growth rate of the fast and slow magnetosonic waves instability is found under the weak neutrino beam approximation and in the absence of ions and neutrals (atoms) collision effect. The numerical illustration of growth rates of the fast and slow magnetosonic waves are also presented with variations of magnetic field angle, neutrino beam energy, neutrino beam density, magnetic field intensity. It is found that the growth rate of the fast magnetosonic wave is maximum in case of the perpendicular directed magnetic field to the direction of wave propagation, while growth rate of slow magnetosonic wave is minimum in that case. It is also noticed that growth rate of fast magnetosonic wave comes out to be larger (of the order tens) than the slow magnetosonic wave case, which is quite different from earlier published results of Type II core-collapse supernova.