Erosion and deposition at the vessel walls of the main chamber of JET were
measured with lone term samples during the whole operation period of the Ma
rk I carbon divertor from April 1994 until March 1995. Assuming toroidal sy
mmetry, about 70 g Ni + Cr + Fe was found to be eroded from the inner torus
wall and about 55 g Be from the outer torus wail due to sputtering by ener
getic charge-exchange neutrals. Deposition has been measured on a poloidal
section of the Mark I C divertor and on tiles from the inner and outer wall
limiters. Eroded material is redeposited in the divertor and in the main c
hamber where it is found predominantly at the sides of the poloidal limiter
s and at the outer vessel wall. At these deposition-dominated areas in tota
l about 25 g Ni + Cr + Fe, 28 g Be and 370 g C are found. The carbon origin
ates mostly from the carbon limiters, additionally some may be originating
from the divertor plates. (C) 1999 EIsevier Science B.V. All rights reserve
d.