Hall-effect thrusters

HaU-Effect Thrusters. The Hall effect (named for Edwin Hall, who discovered it in 1879) states that if a conductor carrying a current is placed in a ms netic field perpendicular to the current, the mj netic field will cause a new current to flow perpendicular to both the magnetic field and the original current... 

Chapter 8 relates to the modehng of Hall-effect plasma thrusters more specifically, small innovative thrusters (referred to as PPIs, as an acron3rm for their name in French). 

As an example of the interaction between surface and plasma in the presence of electrical and magnetic fields, we have chosen to look at Hall-effect thrusters (HETs), the recently-released miniaturized version of them and ways of modeling themd... 

PPI (Petits PropulseTirs Innovants — small innovative thrusters) — a new design for a Hall-effect thruster, hioilt aroimd permanent magnets. Patent FR 0705658 France, Dispositif d ejection d ions a effet Hall [Text] / M. Guyot, P. Renaudin, V. Cagan, C. Boniface. — 2007. 

Figure 8.2. Diagrams a) sectional view (from [BAR 11]) and b) three-dimensional representation, of a classic Hall-effect thruster. The holes in the anode are generally very small indeed (around 100pm in diameter), and the electrical field is strongest around the outlet vent...

We shall now go into greater detail with these equations in order to render them appropriate for a more in-depth study of Hall-effect thrusters. 

Unsteady mono-dimensional model for Hall-effect thrusters... 

Hall-effect thrusters exhibit a geometric configuration facilitating the use of a quasi-one-dimensional model, somewhat like the nozzles in chemical propiilsion (often, we can even adopt the one-dimensional model with a constant straight section on this subject, see Appendix A2). 

A number of authors have established balance equations for these flows, using simplifying hypotheses. For examples, see Barral et al. [BAR 03] and Gascon, Dudeck and Barral [GAS 03] in the steady-state case, or Boeuf and Garrigues [BOE 98] for an initial approach to the low-frequency oscillations in plasma thrusters and, more recently, Barral and Miedzik [BAR 11] for a more elaborate model of these phenomena in the context of a closed-loop study of Hall-effect accelerators. Also see Dabiri et al. [DAB 13]. 

A valid model of a Hall-effect thruster must involve the phenomena observed during normal operation and the influences of the different parameters. Many authors have attempted to construct such a model. 

The system of vmsteady equations shown in Table 8.1 has been applied to the study of looped control of Hall-effect thrusters with the aim of controlling the osdllations of the plasma [BAR 11],... 

Figure A2.1. Diagrammatic representation for a ID model. For further detail, see the diagram of a Hall-effect thruster given by Choueiri CHO 01], and also Figure 8.10 of this book...

In a Hall-effect thruster, the wall of the discharge channel is made of insulating ceramic, and its electrical potential is therefore the floating potential obtained when we have equality (in modulus) of the wall currents of electrons and ions, which gives us the equality(l-[Pg.190]

DAB 13] DABIRI M., DUDECK M., GUYOT M., et al., Plasma properties inside a small Hall effect thruster , 33 International Electric Propulsion Conference, George Washington University, Washington, 6-10 October 2013. 

GUY 08] Guyot M. et al, New Concepts for Magnetic Field Generation in Hall Effect Thrusters , Proceedings of the 5th International Spacecraft Propulsion Conference, Heraklion, Greece, 2008. 

The Appendix gives supplementary information about the balance laws with an electromagnetic field, before going on to describe the methodology used to establish onedimensional equations for a ffow with active walls, as is the case with certain Hall effect thrusters. 

AHE 03] Ahedo E., Gallardo J.M., Effects of the radial plasma-wall interaction on the Hall thruster discharge . Physics of Plasmas, vol. 10, no. 8, pp. 3397-3409,2003. 

---