Hydrogen plasma induced photoelectron emission from metal surfaces
Low temperature hydrogen plasmas are strong sources of vacuum ultraviolet
radiation. The properties of laboratory plasmas can be influenced by surface
processes induced by photons with their energies exceeding the surface work
function of the wall material.
In this work, the plasma induced photoelectron emission has been studied with different ion sources. The emission depends on the mechanical design of the plasma
device, plasma heating method and the discharge power (density). Parametric
studies include the quantifying of the emission from different metal surfaces,
commonly used as plasma facing materials in ion sources, as well as alkali metal
covered surfaces. Experimental studies suggest that low temperature hydrogen
plasma induced photoelectron emission from metal surfaces can reach an order
of magnitude of 1 A per kW of plasma heating power. Furthermore, the emission can increase 2–3.5 times when the metal surface is coated with a thin layer
of alkali metal reducing the work function. The free electrons produced by the
photoelectron emission can influence various plasma processes and especially
the plasma sheath structure, which has been studied using a one-dimensional
analytical model.
...


Publisher
University of JyväskyläISBN
978-951-39-7328-5ISSN Search the Publication Forum
0075-465XKeywords
Metadata
Show full item recordCollections
- Väitöskirjat [3040]
Related items
Showing items with similar title or keywords.
-
VUV-diagnostics of low temperature hydrogen plasmas
Komppula, Jani (University of Jyväskylä, 2015) -
Photoelectron emission induced by low temperature hydrogen plasmas
Laulainen, Janne; Kalvas, Taneli; Koivisto, Hannu; Kronholm, Risto; Tarvainen, Olli (AIP Publishing, 2018)Experimental results of low temperature hydrogen plasma induced photoelectron emission measurements comparing two different plasma heating methods are summarized. By exposing the samples to the vacuum ultraviolet radiation ... -
Quasi-periodical kinetic instabilities in minimum-B confined plasma
Bhaskar, B. S.; Koivisto, H.; Tarvainen, O.; Thuillier, T.; Toivanen, V. (AIP Publishing, 2022)We present the results of an experimental investigation of quasi-periodical kinetic instabilities exhibited by magnetically confined electron cyclotron resonance heated plasmas. The instabilities were detected by measuring ... -
The electron cyclotron resonance ion source with arc-shaped coils concept
Koivisto, Hannu; Suominen, Pekka; Tarvainen, Olli; Spädtke, P. (American Institute of Physics, 2012)The main limitation to further improve the performance of ECR ion sources is set by the magnet technology related to the multipole magnet field used for the closed minimum-B structure. The JYFL ion source group has sought ... -
Study of gasdynamic electron cyclotron resonance plasma vacuum ultraviolet emission to optimize negative hydrogen ion production efficiency
Lapin, R. L.; Skalyga, V. A.; Izotov, I.; Razin, S. V.; Shaposhnikov, R. A.; Vybin, S. S.; Bokhanov, A. F.; Kazakov, M. Yu.; Tarvainen, O. (American Institute of Physics, 2020)Negative hydrogen ion sources are used as injectors into accelerators and drive the neutral beam heating in ITER. Certain processes in low-temperature hydrogen plasmas are accompanied by the emission of vacuum ultraviolet ...