1. 1 US PFC Meeting, UCLA, August 3-6, 2010 DIONISOS: Upgrading to the high temperature regime G.M. Wright, K. Woller, R. Sullivan, H. Barnard, P. Stahle, D.G. Whyte Plasma Science & Fusion Center, MIT, Cambridge USA

2. 2 US PFC Meeting, UCLA, August 3-6, 2010 Outline DIONISOS  Advantages and capabilities The high temperature regime  Importance  Details on upgrades He concentrations and depth profiles in W fuzz layers  Heavy ion ERD analysis

3. 3 US PFC Meeting, UCLA, August 3-6, 2010 DIONISOS has similar capabilities to other linear plasma devices in the US PISCES-B (UCSD)TPE (INL)DIONISOS (MIT) Deuterium ion flux (m -2 s -1 )10 21 –10 23 10 20 - 2x10 22 10 20 -10 22 Ion energy (eV)20–300 (bias)50–200 (bias)20-350 (bias) T e (eV)4 – 405 – 205-10 T i (eV)2 – 52 - 5 n e (m –3 )10 18 –10 19 10 16 - 2x10 18 10 17 -10 19 P max (MW/m 2 )50.50.6 Plasma diameter (mm)7550 Pulse length (s)Steady state Steady-state Activated targetsNoYesNo TritiumNoYesNo

4. 4 US PFC Meeting, UCLA, August 3-6, 2010 What makes DIONISOS unique? Simultaneous plasma and ion beam exposure of targets Active target heating and cooling (T target = 300-750 K) In-situ, time-resolved ion beam analysis In-situ target irradiation by high-energy (~MeV) ions for irradiated materials studies.

5. 5 US PFC Meeting, UCLA, August 3-6, 2010 Why are we interested in the high temperature regime for DIONISOS? Commercial fusion reactors will run with “hot walls” (e.g. 900-1000 K) New physics and surface effects at high temperature. W nanostructure Bubbles Also allows for in-situ target thermal desorption spectroscopy and annealing. Ueda, DIV-SOL ITPA, Amsterdam, May 2009 Baldwin et al, JNM 390-391

6. 6 US PFC Meeting, UCLA, August 3-6, 2010 A new target holder is required to reach these temperatures in DIONISOS Heatwave Labs UHV substrate heater with DC power supply Max operating temperature of 1473 K Electrically isolated from target Mo heat shielding on the sides and back Active PID temperature control (K-type thermocouple) Substrate heater Isolated sample clips for target biassing Heat shielding Power leads

7. 7 US PFC Meeting, UCLA, August 3-6, 2010 Some key differences between the current target holder and the high-T target holder Operating range RT-750 K Active cooling and heating Large targets (> plasma column) Operating range 200-750 K Active heating feedback Small targets (< plasma column) Current target holder High-T target holder

8. 8 US PFC Meeting, UCLA, August 3-6, 2010 Other components must also be protected from the additional radiative heating from the target Hot target leads to radiative heating of sensitive components. Solid-state detectors used for IBA are cooled through thermal contact with a water-cooled plate. Cooling line Heat sink Detector housing Support rod

9. 9 US PFC Meeting, UCLA, August 3-6, 2010 Ion beam analysis on W nano-filament formation has yielded useful new data Fuzz grown in Pilot-PSI with peaked flux and temperature profile. ERD performed with 7 MeV O 4+ ions for He detection. Beam spot is 2.0 x 3.5 mm (oval) Fuzz layer is only 5-10 % density of bulk tungsten.  Penetration depth of 7 MeV O 4+ ions is ~950 nm Center 2mm 4mm 6mm 8mm 10mm

10. 10 US PFC Meeting, UCLA, August 3-6, 2010 W Fuzz has been grown under a variety of conditions W131200C500s W121500C1000s W111500C500s W101500C200s PISCES850C300s PISCES850C1000s PISCES targets have uniform conditions across the surface. Grown in Pilot-PSI with peaked flux and temperature profile. G. De Temmerman, FOM Rijnhuizen, The Netherlands NOT exposure conditions for fuzz growth, just an example of possible gradients in Pilot-PSI exposures.

11. 11 US PFC Meeting, UCLA, August 3-6, 2010 Radial scan on W13 demonstrates transition from fuzz to non-fuzz conditions He is distributed uniformly throughout the fuzz layer. Before fuzz formation, He is peaked at the surface. All other targets had flat He profiles similar to the center of W13 He concentration (at. %)

12. 12 US PFC Meeting, UCLA, August 3-6, 2010 Comparison of He concentrations from all other targets He concentration in the W fuzz falls within 0.5-1.0 at.% for all conditions investigated here. No clear dependence of He concentration on He fluence or surface temperature. More data needed. Controlled parameter scans could reveal hidden dependences.

13. 13 US PFC Meeting, UCLA, August 3-6, 2010 Future goals Further investigations into the dynamics of PSI and PSI for irradiated materials In-situ fuzz growth in Pilot-PSI Time-resolved ERD measurements of W fuzz growth Retention in high-temperature walls under irradiation conditions Characterization of carbon deposition on high- temperature tungsten substrate