Impurity transport studies of intrinsic Mo and injected Ge in high temperature ECRH heated FTU tokamak plasmas Page: 4 of 6

equilibrium (no anomalous transport) and with a peaked NMo profile (NMo (r=0) / Ngo
(r=15 cm)=3). A negligible impurity transport and a central impurity peaking, are
consistent with a neoclassical transport regime.
Calculated spectra at given temperature
70 1 0-r. . . .
-- =2.0keV 140 - calculated
6 - -- T =4.OkeV I
50 --- T =8.OkeV 120 . - -experimental
II 1 120
40 . 0LI- 10
30 I 80
20 * s i : 60 -
3.8 4 4.2 4.4 4.6 4.8 5 5.2 5.4 4 4.2 4.4 4.6 4.8 5 5.2
wavelength (A) wavelength (A)
Fig. 1 Calculated Molybdenum spectra, at low Fig. 2 Best fit of the soft X ray molybdenum
resolution, for a homogeneous plasma at electron spectrum for the shot #12658.
temperature of 2.0, 4.0 and 8.0 keV
Using the laser blow off techinque, germanium was introduced during the current ramp
up phase of an ECRH heated plasmas. The goal was the investigation of the very high
electron temperatures produced and the core impurity transport processes in these
plasmas. While molybdenum is intrinsic, germanium is transient and its time history
gives important information. Two plasmas will be discussed in detail. The first one, shot
#15505, has off axis heating (800 kW) and an injection at t=0.18 s after the onset of
sawtooth activity (t=0.070 s). The plasma current reaches the plateau value at t=0.135s.
The second one, shot #15507, has on axis heating (800 kW) and an injection at t=0.08 s
while the current is still diffusing. The steady state values for both the discharges are
20 -3
Ip=0.7 MA, <Ne> =0.8x10 m and B=5.4 T (on axis heating) or B=5.7 T (off axis
heating). The VUV transitions of Ge were recorded with a grazing incident high
resolution spectrometer (AX = 0.7A). The resonant lines of Li-I, Be-I and K-I like
germanium were detected. These three charge states which exist in a wide temperature
range (3-15 keV), are sensitive to the local electron temperature and transport processes.
These resonant lines ( ,= 122.8 A Li-I like, a= 92.8 A for Be-I like and x=113.8 A for K-
I like) are well measured. Time history of three different charge states: two central (Li-I

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Bracco, F; Crisanti, M; Finkenthal, M; Fournier, K; Gabellieri, G; Granucci, G et al. Impurity transport studies of intrinsic Mo and injected Ge in high temperature ECRH heated FTU tokamak plasmas, article, June 1, 1999; California. ( accessed May 25, 2019), University of North Texas Libraries, Digital Library,; crediting UNT Libraries Government Documents Department.

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