Anomalous electron transport in magnetized low-temperature plasmas

4 problems

• First-principles closure for cross-field electron mobility in Hall thrusters

  Open

  Thruster simulation codes currently need a hand-tuned correction factor for how easily electrons cross the magnetic field. A formula derived from physics would make the codes predictive.

• Why magnetized discharges often show Bohm-scaled cross-field diffusion

  Open

  Since the 1940s, many magnetized gas discharges have been found to leak particles across the field at a rate falling only as one over the field strength, far faster than collisions explain. Why this simple scaling appears in so many devices has no accepted explanation.

• Saturation of the electron cyclotron drift instability and its transport

  Contested

  The leading suspect for the fast electron leakage is a short-wavelength wave driven by the electrons' sideways drift. Whether this wave alone, once it stops growing, carries the observed electron current is not settled.

• Origin and transport role of rotating spokes in E x B discharges

  Open

  Hall thrusters, magnetrons and Penning discharges show bright regions called spokes that rotate around the device thousands of times per second. What drives them and how much electron leakage they cause is unknown.