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N. Schupfer, D. Tskhakaya, R. Khanal, S. Kuhn, F. Aumayr, S. Figueira da Silva, Hp. Winter:
"Effect of particle-induced electron emission (PIEE) on the plasma sheath voltage";
Plasma Phys. Control. Fusion, 48 (2006), 1093 - 1103.

This paper investigates the effect of ion- and electron-induced electron emission
from a material wall on the voltage drop across the adjacent plasma sheath
(`plasma sheath voltage´ (PSV)). For this purpose, a new model involving
a collisionless kinetic sheath consistently coupled to a fluid presheath is
developed. The underlying analysis is valid for plasmas (both magnetized
and unmagnetized) in which the Debye length is much smaller than the
relevant characteristic presheath length (`asymptotic two-scale limit´). Material
boundaries of particular interest are first walls and divertor target plates
bounding magnetically confined fusion plasmas. Majority and impurity ions
accelerated from the bulk plasma towards the material boundary release
electrons flowing back into the plasma, thus giving rise to a lower PSV than
without electron emission. In addition, sufficiently fast electrons from the
plasma impinging on the bounding wall produce secondary electrons and are
also partially reflected. The present work represents a first step in which the
unmagnetized case is considered and electron reflection at the wall is still
neglected. Considering typical boundary-plasma conditions and characteristic
particle-induced electron emission (PIEE) data (i.e. electron yields and energy
distributions), the PSV is self-consistently calculated by means of the new
sheath model, showing appreciable effects of PIEE.

http://aleph.ub.tuwien.ac.at/F?base=tuw01&func=find-c&ccl_term=AC05938283