1 / 13

Michael Bell

A Souvenir of the 36th European Conference on Plasma Physics, Sofia, Bulgaria, 29 June - 3 July 2009. Michael Bell. Conference was a bit smaller than usual. 530 participants 85 invited talks 15 plenary, 70 in 4 parallel sessions 72 contributed talks in 4 parallel sessions

chacha
Download Presentation

Michael Bell

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript


  1. A Souvenir of the36th European Conference on Plasma Physics,Sofia, Bulgaria, 29 June - 3 July 2009 Michael Bell EPS Souvenir / MGB / 090727

  2. Conference was a bit smaller than usual • 530 participants • 85 invited talks • 15 plenary, 70 in 4 parallel sessions • 72 contributed talks in 4 parallel sessions • 699 contributed posters in 4 afternoon sessions • 1.6 presentations per participant! Held in the National Palace of Culture in Sofia EPS Souvenir / MGB / 090727

  3. 1 invited talk and 7 contributed posters from NSTX • "Plasma Response to Lithium-Coated Plasma-Facing Components in NSTX", M. Bell et al. (invited) • "High speed IR camera diagnostic in NSTX", J-W. Ahn et al. • "Multi-energy SXR characterization of stabilized resistive wall modes in NSTX", L. Delgado-Aparicio et al. • "Modeling Fast Ion Transport in TAE Avalanches in NSTX", E. Fredrickson et al. • "Modification of edge plasma profiles in ELM-suppressed discharges with lithium coatings in NSTX", R. Maingi et al. • "Coaxial Helicity Injection Non-inductive Startup on NSTX", B. Nelson et al. • "Fast ion transport by toroidicity induced Alfvén eigenmodes on NSTX", M. Podestà et al. • "High flux expansion divertor studies in NSTX", by V. Soukhanovskii et al. • All had a pretty good reception - good traffic at the posters EPS Souvenir / MGB / 090727

  4. JET • Four invited: • Saibene: “Qualification of the ITER baseline operating scenarios in JET” • Beurskens: “Pedestal identity studies in JET, DIII-D and AUG” • Hobirk: “Improved Confinement in JET Hybrid Discharges” • De Vries: “Identity experiments on Internal Transport Barriers in JT-60U & JET” plus many contributed talks and posters • JET confirms ITER design with proviso that H-mode pedestal behaves as expected (Saibene): pedestal height = pmax  wped • pmax set by MHD but how does wped behave? • JET/DIII-D consistent, so far, with wped *0 and excludes wped *1/2 favorable for ITER (Beurskens) • but DIII-D at top and JET at bottom of range: adequate representation? • JET gets ELM size scaling  *0 whereas DIII-D gets  *>0 • Rotation shear does not affect onset of ITG-related turbulence but does reduce rate of rise of thermal flux with gradient above threshold EPS Souvenir / MGB / 090727

  5. JET (2) • Toroidal field ripple (varied 0.08 - 1.0 %) affects thermal particle transport below level where it is expected to affect fast-ions • ITER may need to add more ferritic shims to get ripple <0.2% • Success in pacing ELMs with pellets, vertical kicks and n = 1, 2 perturbations • reduces ELM size by 30 - 40% but • also degrades thermal confinement by ~10% – concern for ITER • Have not yet suppressed ELMs with magnetic perturbations • Validate specific operational scenarios for ITER • inductive breakdown with Etor 0.2 V/m • low-internal-inductance x-point discharge by early heating • maintained stable H-mode through current rampdown • Campaign now to develop ELM control further and study occurrence and characteristics of H-mode in helium plasmas • Then install and operate ITER-like wall: beryllium and tungsten EPS Souvenir / MGB / 090727

  6. Hobirk: “Hybrid Modes” in JET • Raised many questions and, for me, hackles • JET definition: q0 > 1 or slightly below 1 and a broad region of low magnetic shear with no sawteeth and “mild” NTMs • HH ≈ 1 in JET whereas HH up to 1.5 in DIII-D • Conjectures HH scales with *  not good for ITER • JET uses LH and/or current ramps to set up “hybrid” q-profile • Current ramp-up modified q0 but HH and N limit unchanged • However, current ramp-down increased HH to 1.35 and N limit to 3 %.m.T/MA • Was speaker aware of TFTR results on this? - No! • When plotted against current before rampdown was there a benefit? - Didn’t know • Benefit died out after ~2s ~ current diffusion time • Stability of “AT” regimes in JET also discussed by Buratti O2.007 • Highest N ≈ 4 %.m./MA for qmin ≈ 1; no RWMs in JET EPS Souvenir / MGB / 090727

  7. Huysmans “3D non-linear MHD simulations of ELMs • JOREK code encompasses core and open field lines out to conducting boundary • Applied to JET-like equilibrium • Large Jedge due to bootstrap current in edge pressure gradient • Sees growth of pure ballooning mode with dominant n = 9 • For equilibrium from plasma with smaller ELMs, gets n = 18 • Plasma expelled onto open field lines – cools and detaches • Sees fine structure of heat flux to outer divertor target • ELM is not one event but involves discrete bursts over ~200µs • Applied to pellet triggering of ELMs • Model as big local ne perturbation • Pellet triggers low-n, typically n = 2, ballooning-like instability through effect on J(r), p(r), irrespective of pre-existing profiles • Ergodizes edge EPS Souvenir / MGB / 090727

  8. ASDEX-Upgrade (AUG) with Tungsten Wall • E. Wolfrum “Investigation of H-mode Pedestal Physics in AUG” • Program R(t) synch’ed to ELM cycle to get high-resolution profiles • Use T(Rsep) defined by 2-point power balance model to locate Rsep • Showed pmax evolving to common limit but well before ELM • So, maybe the pedestal gradient is actually set by transport and • Something else is evolving to trigger ELM: J(r) • Pegourié “Fuelling and plasma control by pellet injection with application to ITER” • ASDEX experience: with HFS pellets, need only get to ~1/2 pedestal height to fuel core • For ITER fueling 5mm pellets on HFS at 10 – 15 Hz probably OK • For ELM triggering, 2.2mm pellets on LFS at 10 – 25 Hz needed • Just within capability of ITER cryo-pumps and tritium plant EPS Souvenir / MGB / 090727

  9. ASDEX-Upgrade (AUG) with Tungsten Wall • G. Pautasso “Disruption studies” - massive He,Ne,Ar injection • achieved about 1/4 of density needed in ITER to suppress runaways • V. Rohde “Wall Retention of Deuterium and Gaseous Impurities” • Operated without boronization for many months after W wall installed • Bake only to 150°C • Also eliminated HeGDC • He became buried in W and released later • W-wall recycles deuterium 1 - RD ~ 1.5% • Up to 1/3 of input D held briefly on wall – released over ~10 min • Now puff N2 to maintain edge radiation • Used to be provided by intrinsic C but C lower with all W-wall • Better overall performance than with carbon wall • Related results also in posters (Kallenbach, Herrmann and others) • AUG will return to operation with 2 generators this month EPS Souvenir / MGB / 090727

  10. MAST • E. Nardon “ELM control by resonant magnetic perturbations on MAST” • Upper, lower outboard rows of 6 coils each; 6kA-turns • In L-mode get pump-out ne/ne ~ -50% and splitting of outer strike point • Perturbation threshold consistent with ergodization of edge • In DN H-modes, Type III ELMs become dithering with RMP • With Type I ELMs, little effect even with (vacuum) ergodization N > 0.94 • In LSN H-modes, perturbation returns discharge to L-mode • M. Turnyanskiy “Off-axis NBCD experiments on MAST” (contributed) • Displace plasma down - plasma volume does decrease ~10% • Need to move back to midplane to make measurements • TRANSP calculates hollow deposition profile and JNBCD • TRANSP over-predicts Wtot, SDD by 25 - 30 % at 4 MW (better at lower P) • Correlate with fishbone activity • Model with HAGIS code  add anomalous Dfi ~ 0.5 m2s-1 in TRANSP EPS Souvenir / MGB / 090727

  11. Tuesday Evening Session on New Facilities • ITER status (A. Loarte, IO) • Mainly discussed Scenario 1 for construction and operation • First plasma with limited capability and diagnostics in late 2018 • Followed by 2+ years of installation, commissioning • Start serious research in H, He plasmas with H&CD in 2021 • Accelerate research and licensing to reach full DT operation in 2027 • JT-60SA (S. Ishida, JAEA) – JA-EU joint project at Naka • “Re-baselined” in 2008 to reduce cost, regain schedule - dumped • TF built in EU, PF in JA, all ferritic steel VV • Reduce B to 2.2T but keep 5.5MA by lower A = 2.5, higher  = 1.9 • NNBI 10MW, PNBI 24MW, ECH 7MW, all for 100s pulse • Full remote handling because of high DD neutron yield 1.5E21 /year • First plasma in 2016, planned to operate for 15 years EPS Souvenir / MGB / 090727

  12. Tuesday Evening Session on New Facilities (cont.) • FAST (F. Zonca, ENEA) – “ITER satellite” at Frascati site • Aimed to study fast-ion physics created by ICH instead of fusion • Want to be similar in dimensionless parameters to ITER but have to compromise • * has to go! • Based on cryogenically cooled (20K start) copper TF • R = 1.82m,  = 1.7, BT = 8 (8.5) T, Ip = 6.8 (8.0) MA for 170s (shorter) • Mainly rely on ICH but planning for NNBI and ECH too! • Full tungsten wall • Admits challenge of this with ICH • Question: why is this being built and who will pay for it with ITER demanding more resources? EPS Souvenir / MGB / 090727

  13. Other Presentations and Points of Interest (to me) • Angioni (I4.060): Particle transport in tokamaks • Mused on and extolled virtues of density profile peaking for ITER • Paley (I3.045): Plasma control in TCV with ECH • ECH with control of launch angle to broaden J(r) for high- (≈ 2.8) • Implemented real-time analysis of data from 64 channel SXR fan • Allowed control of sawteeth by depositing ECH in-/out- side q = 1 • Control code is adaptive to plasma response • Some hysteresis in response due to cumulative heating • Imbeaux (O2.018): Long-term plasma control in Tore-Supra with LH • Control of LH power by MHD signatures only: OK but not great • Plan to use polarimetry • Van de Sanden (I2.022): Solar cell technology and developments • Ebert (I4.059): Sprite discharges and terrestrial gamma-ray bursts • 50/day, energy > 35MeV: big noisy spectacular stuff! EPS Souvenir / MGB / 090727

More Related