Anomalous Transport induced by Sheath Instability in Hall Effect Thrusters
نویسندگان
چکیده
It is well recognized to ascribe the anomalous cross-field conductivity inside Hall-effect thrusters to fluctuation-induced transport due to gradient-driven instabilities (Rayleigh or electron drift) and to electron-wall interaction (near-wall conductivity). In this contribution we have performed a 2D(r,θ) Particle-in-Cell (PIC) model showing the possibility of another mechanism inducing azimuthal fluctuations: the lateral sheath instability. It is created by a negative differential resistance of the current-voltage I-V characteristic of the floating wall as a consequence of high secondary electron emission. Azimuthal modes characterized by frequencies multiplies of v0=3 GHz and a wave number kθ=80 rad have been detected. By means of a 2D(θ ,z) Test-Particle Monte Carlo (TPMC) simulation and using the characteristic azimuthal oscillations found in the previous PIC simulation, we have assessed the induced anomalous transport. The contribution calculated is in good agreement the electron cross-field conductivity measured in the acceleration region.
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