Behaviour of neutral hydrogen atom density in the presence of a sample holder in a plasma reactor

• Published in: Vacuum Vol. 84; no. 1; pp. 90 - 93
• Main Authors: Drenik, A., Tomeljak, A., Mozetic, M., Vesel, A., Babic, D., Balat - Pichelin, M.
• Format: Journal Article
• Language: English
• Published: Elsevier Ltd 25-08-2009; Elsevier
• Subjects: Atom recombination; Density; Engineering Sciences; Fiber optics; Fibre Optic Catalytic Probe; Hydrogen atoms; Hydrogen plasma; Materials; Optical fibers; Plasmas; Reactive fluid environment; Reactors; Sample holders; Silica glass; Weakly ionised plasma; Weakly ionised plasma; Atom recombination; Fibre Optic Catalytic Probe
• ISSN: 0042-207X; 1879-2715
• DOI: 10.1016/j.vacuum.2009.04.068

The behaviour of density of neutral hydrogen atoms in the presence of a sample holder in a MESOX reactor was studied. The MESOX reactor is used for studying interaction of hydrogen atoms with solid state surfaces at extreme conditions. Concentrated solar radiation with power of approximately 6
kW is collimated to a spot with the surface in the order of magnitude 1
cm
2 thus allowing for independent sample heating above 2000
K. Hydrogen plasma is generated in a MW (microwave) discharge. The H-atom density is measured with a FOCP (Fibre Optics Catalytic Probe). The H-atom density in the empty reactor depends slightly on the pressure and MW power and is about 5
×
10
21
m
−3 at a power of 1000
W. The sample holder made from quartz glass was mounted in the centre of the reactor and the H-atom density was measured versus time. The H-atom density in the loaded reactor was decreasing continuously. After a time period in the order of 2
min, the H-atom density was reduced by approximately a factor of 3 in regards to the original value. The results were explained by taking into account a temperature dependence of the recombination coefficient for heterogeneous recombination of H atoms on the quartz surface.