Ljubljana, 1-2/10/2009 Meeting of the High-Z SEWG of PWI TF

ENEA-Frascati activities on high-Z materials

G. Maddaluno

Outline

1. Impurity seeding experiments on FTU

(WP09-PWI-05-01/ENEA /PS and BS)

2. Deuterium retention in W

3. Thick W coatings (WP09-PWI-05-03/ENEA /PS and BS)

Ljubljana, 1-2/10/2009 Meeting of the High-Z SEWG of PWI TF

Toroidal limiterTZM

Vacuum vesselStainless steel

Sample

FTU Plasma facing materials

Ljubljana, 1-2/10/2009 Meeting of the High-Z SEWG of PWI TF

Tungsten and Molybdenum sputtering yields

From “Sputtering by Particle Bombardment”Rainer Behrisch, Wolfgang Eckstein (Eds.)Springer Berlin / Heidelberg 2007

(based on Yamamura Y. et al.1983, Technical report IPPJ-AM 26 Nagoya, Japan)

Ljubljana, 1-2/10/2009 Meeting of the High-Z SEWG of PWI TF

Ne seeding experiments on FTU in 2009

• After the operation restarting of FTU, following a long shutdown, some short experimental time was dedicated to testing the effect of Ne injection on the production of high-Z impurities.

• Mo production from the toroidal and poloidal limiters was monitored in the visible and UV wavelength range, pre and post injection of Ne lasting up to 20 ms.

• Ohmic discharges with BT = 6 T, Ip = 500 700 kA, ne = 0.7 1.6 1020 m-3.

• The erosion of, as well as the ion flux impinging on, a W sample introduced in the bottom of the vacuum chamber by means of the FTU Sample Introduction System was monitored by visible spectroscopy.

• Data analysis is in progress. New dedicated experimental days are foreseen in Autumn.

Ljubljana, 1-2/10/2009 Meeting of the High-Z SEWG of PWI TF

Evolution of Ne and Mo visible lines after Ne puff (20 ms)BT= 5.9 T, Ip = 0.5 MA, <ne> = 0.8 1020 m-3

Ne

Mo

Ne flux

AU

AU

Ljubljana, 1-2/10/2009 Meeting of the High-Z SEWG of PWI TF

Ne visible lines evolution after Ne puff (t = 0.8 s) BT= 5.8 T, Ip = 0.5 MA, <ne> = 1.0 1020

NeMo

Ne

Ljubljana, 1-2/10/2009 Meeting of the High-Z SEWG of PWI TF

Ne visible lines evolution after Ne puff (t = 0.6 s) BT= 5.9 T, Ip = 0.7 MA, <ne> = 1.6 1020

t = 0.5 s

t = 0.6 s

t = 0.7 s

t = 0.75 s

Mo Ne

Ljubljana, 1-2/10/2009 Meeting of the High-Z SEWG of PWI TF

W samples

Pre- exposure Exposed

Ljubljana, 1-2/10/2009 Meeting of the High-Z SEWG of PWI TF

W sample exposed in the FTU SOL

Ljubljana, 1-2/10/2009 Meeting of the High-Z SEWG of PWI TF

TDS measurement of the retained deuterium was carried out.

HD and D2 content is to be exactly quantified, but it seems very low, as expected for W: moreover the duration of exposure in the FTU SOL was also rather short (17 discharges).

10-13

10-12

10-11

10-13

10-12

10-11

0 2000 4000 6000 8000 1 104 1.2 104

HD

, D

2 (

A)

Elapsed time[s]

100

1000

0 2000 4000 6000 8000 1 104 1.2 104

T_

pir

(°C

)

10-13

10-12

10-11

10-10

10-9

10-8

10-7

0 500 1000 1500

calibration_A vs time

Ljubljana, 1-2/10/2009 Meeting of the High-Z SEWG of PWI TF

Development of thick W coatings

• The activities on the development of thick W coatings began with large delay because of availability problems with the collaborating company.

• The goal is the development of thick ( 3 mm) W coating on stainless steel substrate (thickness ~ 10 mm) with mixed interlayer by HPPS technique.

• First tests on small pieces are in progress.• Main problems are related to obtaining coatings with homogeneous

thickness on larger substrates while avoiding to degrade their adhesion by interrupting the process.

• Collaboration with CNR-Milano and Politecnico of Milano has been set for a comparative study of W coating deposited by plasma spray and pulse laser deposition.

Ljubljana, 1-2/10/2009 Meeting of the High-Z SEWG of PWI TF

W coating deposited on a SS test sample