| AVS 58th Annual International Symposium and Exhibition | |
| Plasma Science and Technology Division | Wednesday Sessions |
| Session PS-WeA |
| Session: | Plasma Sources |
| Presenter: | Noah Hershkowitz, University of Wisconsin-Madison |
| Authors: | N. Hershkowitz, University of Wisconsin-Madison L. Oksuz, Suleyman Demirel University, Turkey J.P. Sheehan, University of Wisconsin-Madison |
| Correspondent: | Click to Email |
Negative plasma potentials were obtained in DC hot filament unmagnetized electropositive argon plasma in two configurations. For sufficiently low plasma density (<106 cm-3) bounded by conducting walls, double layers provide ion and electron confinement near the walls. Similar results were observed in higher density plasmas (~109 cm-3) when a thin dielectric coating of oil covered the surface of the conducting walls. The potential profiles, measured using emissive probes in the limit of zero emission, from the center of the plasma to the potential minima are quite similar in shape to those observed when the plasma has positive plasma potentials. The primary electrons emitted from the filaments are important for charge conservation and for modification of the Bohm criteria but are not important for current balance.
This work was supported by US Department of Energy grants No. DE-AC02-09CH11466 and No. DE-FG02-97ER54437, and the Fusion Energy Sciences Fellowship Program administered by Oak Ridge Institute for Science and Education under a contract between the U.S. Department of Energy and the Oak Ridge Associated Universities.