ADVANCED FUSION TECHNOLOGY RESEARCH AND DEVELOPMENT ANNUAL REPORT TO THE U.S. DEPARTMENT OF ENERGY OCTOBER 1, 1998 THROUGH SEPTEMBER 30, 1999 Page: 26 of 44

                                
ASDEX

DI II-D
10     net r edeposition
0
net erosion
ISP        OP
80                          V
40                           a
0
1.0        1.4       1.8
Major Radius (m)

Iner Wall    CTile#                              19
-  H e a t  S h ie ld  IC R n n
R=2.3m             R=3.1 m
f    ISP        Plasma-
Divertor Plates                                   Fai ng
1                      0f
400
350                               0___                        -
300       IPBe Target                                Entire
40                                                  Top Surface
9                       200-   ,     ;
02020                                                  Carbon
Target
0             -
0    0.2  0.4   0.6  0.8               5      10     15
Distance Along Divertor Plates (m)         Tile number

DAC: Trapped D concentration over -1 year of tokamak operation, primarily attached outer divertor operation
Fig. 6-2. Review of erosion/redeposition data related to trapped deuterium concentrations led to
identification of similar erosion/redeposition patterns on all major tokamaks.
TUNGSTEN EXPOSURE
A tungsten sample was exposed to -15 partially detached divertor plasma discharges
during a plasma flow measurement experiment. The La2O3 tungsten-alloy ITER
prototype alloy was used. The exposures were primarily near the outer strike point and
private flux region. Visual inspection of the exposed tungsten sample showed a uniform
redeposited layer, presumably of carbon, in agreement with the previous DiMES
measurements which showed partially detached divertor plasmas to have net redeposition
at the outer divertor leg. Auger spectroscopy confirmed a uniform deposition of mostly
carbon at a rate of about 2 nm/s. No arc traces were found on the sample, in agreement
with previous DiMES experiments exposed to detached plasmas.
CONFERENCES/MEETINGS
1.   A DiMES program status was presented at the High Heat Flux Components and
Plasma Surface Interactions workshop in Japan in October, 1998.

Fusion Technology Development Annual Report 6-3

a)
Oc 0
z
0s

General Atomics Report GA-A23325

JET (Mkl)