|Title||Plasma temperature rise toward the plasma-facing surface|
|Publication Type||Journal Article|
|Year of Publication||2015|
|Authors||D. Nishijima, R.P Doerner, R.P Seraydarian, G. De Temmerman, H.J van der Meiden|
|Journal||Journal of Nuclear Materials|
|Pagination||440 - 444|
Detailed measurements of axial electron temperature, Te, profiles in the presheath region were carried out using a Langmuir probe and the line intensity ratio technique for both He I (728.1 nm/706.5 nm) and Be II (467.3 nm/313.1 nm). The results show that Te increases toward the material surface, which contradicts the standard picture that Te is constant along the magnetic field in the sheath-limited regime. While no target bias voltage, Vb, dependence is seen, the Te rise becomes more prominent with decreasing neutral pressure. Similarly, the ion temperature, Ti, evaluated from Doppler broadening of a He II line emission at 468.6 nm is found to increase toward the surface, but also does not depend on Vb. Possible mechanisms of the Te and Ti rise as well as validity of the line intensity ratio technique near the material surface are discussed.
|Alternate Title||J. Nucl. Mater.|
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