Magnetic Nozzle Plasma Plume: Review of Crucial Physical Phenomena

Abstract

This paper presents a review of the current understanding of magnetic nozzle physics. The crucial steps necessary for thrust generation in magnetic nozzles are energy conversion, plasma detachment, and momentum transfer. The currently considered mechanisms by which to extract kinetic energy from the plasma include the conservation of the magnetic moment adiabatic invariant, electric field forces, thermal energy directionalization, and Joule heating. Plasma detachment mechanisms discussed include resistive diffusion, recombination, magnetic reconnection, loss of adiabaticity, inertial forces, and self-field detachment. Momentum transfer from the plasma to the spacecraft occurs due to the interaction between the applied field currents and induced currents which are formed due to the magnetic pressure. These three physical phenomena are crucial to thrust generation and must be understood to optimize magnetic nozzle design. The operating dimensionless parameter ranges of six prominent experiments are considered and the corresponding mechanisms are discussed.

Quasi-one-dimensional code for particle-in-cell simulation of magnetic nozzle expansion

“…Equation 8 gives the approximate radial magnetic field a particle orbiting around the axis of symmetry would experience and can be used in the conventional particle pushing algorithms.…”

“…Similarly, magnetic nozzles accelerate a high temperature plasma generated in the plasma source by using a strong guiding magnetic field. [8][9][10] Magnetic nozzles also have applications to improve performance of magnetoplasmadynamic thrusters. 11,12 Figure 1: Comparison between de Laval nozzle and magnetic nozzle.…”

Modeling of plasma processes in the slowly diverging magnetic fields at the exit of an applied-field magnetoplasmadynamic thruster

“…7 In order to examine the character of magnetic expansion effects, the effects of magnetic fields produced by solenoid coils have been studied with numerical calculations, analyses, and experimental measurements. 8 The studies were mostly conducted for practical plasmas generated in HPT, VASIMR, AF-MPDT, and ECR (Electron Cyclotron Resonance) heating. 9 These studies can be divided into two components: (1) the plasma acceleration process which is chiefly comprised of electrothermal and electromagnetic forces, and (2) the detachment process which plays an important role in promotion of thruster performance.…”

Investigation of Plasma Exhaust Profile Manipulation Using Magnetic Fields

“….......................................................................................... Figure 3: "Specific impulse and thrust comparison for space propulsion methods" [5] ............... (10 sec.) ............................................................................................…”

“…"Electric propulsion can produce thrust by electrically heating propellant, electrostatically accelerating charged particles, or manipulating the flow of charged particles with electromagnetic fields" [5]. The proposed experiment measures the MPD expansion effects of a toroidal magnetic field on an ionized hypersonic exhaust flow.…”