Observations of electric double layers in a magnetised plasma column

Abstract

Strong electric double layers are produced in a low-density plasma column confined by an axial magnetic field and maintained by single-ended inflow of plasma along the magnetic field. The double layer evolves from an anode sheath, and ionisation within the sheath is shown to be a significant process in this conversion. Once the double layer has been formed, its axial position can be controlled by the external electric circuit. The layer exhibits an axial motion back and forth with amplitudes somewhat larger than the layer thickness.

Active experiments in space, laboratory experiments and numerical simulation.

“…The double layers occur most often in the thin discharge tubes in the place where the tube diameter drastically changes. The distinct DL not being related to the wall, was detected by TORVEN and ANDERSSON (1979) in the discharge with the weak magnetic field. The plasma flow was injected from the cathode alongg the field.…”

Double Layer Dynamics in a Collisionless Magnetoplasma

“…Single-ended operation Strong DLs (eA+/T e >1) can also be produced by injecting an electron beam into a plasma 6 ' 9 ) due to the space charge effects of the beam. Furthermore, DLs were observed in discharge plasmas, where they were found to form from the anode sheath [10][11] ). However, in discharge plasmas with internal ionizations the DL potential is limited by the ionization potential of the background g as 4,12).…”

Sheaths: More complicated than you think

“…18. 33 Ion acceleration can also be provided by combinations of several presheaths or double-layers. Multiple double-layer structures have been observed 34 in laboratory plasma ͑see Fig.…”