R. Doerner, PFC Program Meeting, MIT, July 8-10, 2009 Mixed Interactions of W, Be, C, D & He R. Doerner for the PISCES Team In collaboration with members of the US domestic fusion program, the EU & Japanese programs, and the ITPA DIV/SOL

R. Doerner, PFC Program Meeting, MIT, July 8-10, 2009 W Temperature & PMI are coupled NAGDIS-II: He plasma D. Nishijima et al. JNM (2004) Surface morphology Shallow depth Micro-scale PISCES-A: D 2 -He plasma M. Miyamoto et al. NF (2009) K, 1000 s, 2.0x10 24 He + /m 2, 55 eV He + Little morphology Occasional blisters PISCES-B: pure He plasma M.J. Baldwin et al, NF 48 (2008) K, 4290 s, 2x10 26 He + /m 2, 25 eV He + NAGDIS-II: pure He plasma N. Ohno et al., in IAEA-TM, Vienna, K, s, 3.5x10 27 He + /m 2, 11 eV He nm (VPS W on C) (TEM) ~ K> 2000 K ~ 900 – 1900 K Surface morphology Evolving surface Nano-scale ‘fuzz’

R. Doerner, PFC Program Meeting, MIT, July 8-10, 2009 Mixed D/He reduces D retention in W at low temperature dateD Fluence D/m 2 D retained D/m 2 12/ (+He) / / / / With He PISCES ●Addition of He to the D plasma reduced D retention by about a factor of 35. ●With He, D retention is mainly at the surface, whereas without He, D retention peaks ~ 1 micron beneath the surface. See more details in talk of D. Nishijima 1e21 D/m 2 ~ 3 mg/m 2

R. Doerner, PFC Program Meeting, MIT, July 8-10, 2009 At higher temperature, W ‘fuzz’ forms and is approx. 95% space SEM used to profile ‘fuzz’ layer thickness over sample surface. Geometric vol. of ‘fuzz’ layer est. (7.8 x m 3 ±10%). ‘Fuzz’ layer removed. Mass change (D m =0.87 mg ±1%). Comp. w/ pure W, (  = x10 3 kgm -3 ), ‘fuzz’ layer is 94 % porous. PISCES

R. Doerner, PFC Program Meeting, MIT, July 8-10, 2009 If ‘fuzz’ is removed at equilibrium rate at 1120 K– 500 nm length: 1.4  g.s -1 m -2, 0.62 g W per ITER shot 1600 shots to W dust limit. 10 nm length, 69  g.s -1 m -2, 0.3 kg W per ITER shot 320 shots to W dust limit. Assuming ITER shot of 400 s and total strike point area w/ ‘fuzz’ growth to be 10 m 2. ITER W dust limit is 100 kg. A TOKAMAK experiment to measure ‘fuzz’ erosion is NECESSARY. ‘Fuzz’ growth is fastest at early times PISCES

R. Doerner, PFC Program Meeting, MIT, July 8-10, 2009 Erosion rate of W fuzz Measurements are underway to determine erosion yield and angular distribution of eroded W fuzz PISCES Integrated W atom surface loss rate from a nanostructured surface Sputtered Ar on W angular distribution from a smooth surface W fuzz Smooth W

R. Doerner, PFC Program Meeting, MIT, July 8-10, 2009 What about effects of D + He plasma on other ITER materials PISCES D +10% He plasma also reduces retention in Be targets and alters surface D +10% He plasma on ATJ graphite has no effect on retention or surface Pure D Plasma on Be 200°C D+0.1He Plasma on Be 200°C Surface pits

R. Doerner, PFC Program Meeting, MIT, July 8-10, 2009 PISCES Retention in Be codeposits resulting from mixed D/He plasma exposure is also being investigated Co-deposits (from Be targets eroded by D2 and D2-He plasmas) is collected on W witness plates TDS up to 800 C shows a small release of He from mixed species D2-He-Be co-deposits D2 release behavior is not significantly altered by the presence of He Total D2 retention is increased by in the D2-He plasma case, but D/Be ratio is more relevant Be concentration is currently being measured by NRA at IPP

R. Doerner, PFC Program Meeting, MIT, July 8-10, 2009 High priority ITPA DIV/SOL R&D tasks The ITPA DIV/SOL group and ITER IO have identified 5 critical areas of R&D where community input is needed. While parts of the US PFC Program are included in the R&D effort, more involvement is encouraged. The next meeting of the ITPA DIV/SOL group will be at UCSD during Dec , All are welcome to attend and contribute to this effort. The 5 primary R&D areas, along with the coordinators of those areas, are: 1) T retention – J. Roth and R. Doerner 2) Tungsten – A. Kallenbach and Y. Ueda 3) Dust – D. Rudakov and N. Ashikawa 4) Heat flux – A. Leonard and M. Lehnen 5) Erosion and Material Migration – P. Stangeby and V. Philipps PISCES

R. Doerner, PFC Program Meeting, MIT, July 8-10, 2009 Proposed T retention and removal work plan 1.Refine ITER prediction (MIT mini-meeting) : High priority Participants (JAEA, FZJ, UCSD, IPP, Kyushu, CEA, MIT, UofT, Sandia, ITER, JET, FOM) 2.Fuel retention machine database : High priority Participants (FZJ, MIT, CEA, IPP, JET, GA, JAEA) 3.Ion cyclotron wall cleaning : High priority Participants (VR, FZJ, MIT, CEA, IPP, JET, EAST, NIFS) 4.Disruption flash heating : Med. priority Participants (CAE, UCSD, UKAEA, ITER, JET, MIT, GA) 5.Capability and risks of removing C : Med. priority Participants (UofT, VR, FZJ, CEA, IPP, JET, GA) 6.Isotope exchange : Med. priority Participants (JAEA, MIT, CEA, IPP, INL, Kyushu, FZJ, JET, GA) 7.T removal by heating to 350C : High priority Participants (MIT, CEA, UCSD, IPP, INL, Sandia, UKAEA, GA. FZJ) 8.Retention in gaps : Med. priority Participants (FZJ, IPP, INL, UKAEA, Kyushu, JET, GA, JAEA) 9.Influence of mixed species on retention : High priority Participant (UCSD, IPP, Kyushu, FZJ, JAEA, UofT, JET) R&D type Time scale Report Short (1-2 yr) DSOL (new) Med. (2-4 yr) Report Med. (2-4 yr) Med. (2-4 yr) Short (1-2 yr) Short (1-2 yr) Short (1-2 yr) DSOL (with Material Migration) Med. (2-4 yr) Collabo- ration Short (1-2 yr) Collabo- ration DSOL (new) DSOL (new)

R. Doerner, PFC Program Meeting, MIT, July 8-10, 2009 Different heating profiles and different implantation doses are being studied Six types of material – Be on W Be on CFC Be 12 W Be 2 C C on Be W on Be Four implantation doses - 3 E 16 D atoms (at room temp.) 3 E 17 D atoms 3 E 18 D atoms 3 E 19 D atoms PISCES 350C

R. Doerner, PFC Program Meeting, MIT, July 8-10, 2009 Retention and release from mixed material samples with Be-containing overlayers 200 nm Be layers deposited on substrates at MEdC, Romania Alloys formed and verified at IPP, Garching Samples implanted at room temperature with 200 eV D ions at IPP, Garching to a fluence of 4-5 E22 D/m 2 (~3 E18 D atoms) TDS performed on samples at PISCES, UCSD Assumes all D is released from samples by TDS at 800C (to be confirmed by post-TDS NRA at IPP, Garching) Be on W Be on CFCBe 2 CBe 12 W Total D released 1.3E17 7.4E165.2E16 PISCES

R. Doerner, PFC Program Meeting, MIT, July 8-10, 2009 Annealing to 350C is ineffective for release from C layers W layers retain very little implanted D PISCES 350 C

R. Doerner, PFC Program Meeting, MIT, July 8-10, 2009 PISCES continues to contribute to ITER R&D Mixed material/mixed plasma species effects on erosion, codeposition, retention and surface evolution Impact of transient heating on fuel retention and surface loss rates Plasma impurity transport, flow speed measurements and modeling comparison Active collaborations continue with members of the US fusion program, EU, Japan, China and the ITER IO PISCES