Characterization and Optimization of a Plasma Window for Reducing Gas Flow from High Pressure
Abstract
The plasma window is a DC cascaded arc, in argon or helium, which restricts gas flow from a high pressure cell (order 102 torr). This has applications in instances where a vacuum-atmosphere interface is present, for example as a component of a high pressure gas charge stripper in a high intensity ion accelerator such as the Facility for Rare Isotope Beams (FRIB). The factor by which flow is restricted is up to about 20 due to dramatically increased temperature and viscosity. A relation is developed for the flow rate from the gas cell as a function of pressure, current, and channel geometry. Insights are given on how the flow rate is related to basic plasma quantities such as electron density (in argon, about 1016 cm-3) and temperature (in argon, about 1.5 eV), determined via Stark broadening and relative emission intensities respectively. Results are compared with a cascaded arc model in PLASIMO, which has yielded comparable properties to measurements. This work can serve as a guide with which the geometry of the plasma window can be optimized, maximizing gas pressure while minimizing escaping gas flow.
This work is supported by NSF Award PHY-1565546.- Publication:
-
APS Division of Plasma Physics Meeting Abstracts
- Pub Date:
- 2019
- Bibcode:
- 2019APS..DPPCM9001L