ANALYTIC CRITERIA FOR POWER EXHAUST IN DIVERTORS DUE TO IMPURITY RADIATION

Impurity radiation is a key mechanism in divertor concepts to transfer the energy from the edge plasma to the main chamber and divertor cham ber walls [G. Janeschitz, J. Nucl. Mater., to appear (1994)]. Using AD PAK impurity radiation rates [R. Hulse, Nucl. Techn./Fusion 3 (1983) 2 59; D.E. Post, R.V. Jensen, C.B. Tarter, W.H. Grasberger, W.A. Lokke, At. Data Nucl. Data Tables 20 (1977) 397], we have developed criteria both for the required impurity fraction, impurity species, connection length and mid-plane electron temperature and density and for the requ ired enhancement over coronal equilibrium due to charge exchange recom bination and impurity recycling to radiate a given power for Be, C, Ne , and Ar [L. Lengyel, IPP, 1/198 (1981); P.H. Rebut, B.J. Green, Plasm a Physics and Controlled Nuclear Fusion Research 1976, vol. 2 (IAEA, 1 977) pp. 3-17; K. Lackner, R. Schneider, Fusion Eng. Design 22 (1993) 107; R.A Hulse, D.E. Post, D.R. Mikkelsen, J. Phys. B 13 (1980) 3895; J. Hogan, Physics of Electronic and Atomic Collisions, S. Datz, ed. (N orth-Holland, Amsterdam, 1982); S. Alien, M. Rensink, D. Hill, R. Wood , J. Nucl. Mater. 196-198 (1992) 804].