Summary of CDBM Joint Experiments

11th Meeting of the ITPA CDBM TG, Chengdu, 23-24 Oct. 2006 Summary of CDBM Joint Experiments Mon. 23 Oct, morning T. Takizuka (JAEA) CDB-2: Confinement scaling in ELMy H-modes; β degradation C.C. Petty (J. DeBoo) CDB-6: Improving the condition of the ITPA database; Low R/a NSTX 2006 results and 2007 plans are also reported B τ th ~ β -0.1 ν* -1, τ th ~ B T 0.9 I p 0.4 S. Kaye CDB-8: ρ* scaling along an ITER relevant path at both high and low β D. McDonald CDB-9: Density profiles at low collisionality H. Weisen (W. Houlberg) CDB-4: ν* scan at fixed n/n G <J. Snipes> No report

CDB-2: Confinement scaling in ELMy H-modes; β degradation Spokesperson: C.C. Petty Tore Supra: L-mode experiments found a weak β dependence of τ E. Turbulence level (reflectometer) did not change outside of q=1with increasing β. AUG: Both global and local analyses of H-mode experiments with δ upper = 0.05 yield a degradation of confinement which is linear in β. NSTX: Weak β dependence (τ β -0.1 ) was measured for κ = 2.1 and δ = 0.6. JET: Experiments planned for a hybrid-like scenario in November 2006 AUG: In 2007, experiments on this topic will be severely limited. However, studies relating β dependence, edge conditions and collisionality will be attempted MAST: Experiments planned for 2007, subject to NBI availability NSTX: Additional experiments in 2007 will look at effect of lower κ and δ on β scaling JET, JT-60U, AUG, DIII-D: Examine whether weaker upper triangularity in H- mode discharges is responsible for the β dependence?

Status of Contributions to CDB-2: Nov proposal, Jan, April Confinement scaling in ELMy H-modes: β degradation) Spokesperson: C.C. Petty JET: Experiments planned for a hybrid-like scenario in early 2006. AUG: Experiments foreseen in 2006. JT-60U: Experiments done, no new experiments in 2005. Journal paper in review. MAST: Experiments planned for 2005/6, subject to NBI availability. NSTX: Experiments planned for 2006 if operation at higher field is allowed. TS: L-mode experiments with ICRH & LH scheduled for November 2005. Electron density and temperature fluctuations will be measured with 3 reflectometers and ECE. JET, AUG, DIII-D: Examine whether weaker upper triangularity in H-mode discharges is responsible for the beta dependence? JET: Extend experiments to higher β, plans for d effect will be discussed at CDBM meeting at PPPL in April. AUG: β scaling experiments to be done in early 2006, but not δ dependence. DIII-D: not doing this year, but on the extended list for future work. AUG: Planned experiments have been started in (January - March) and will be continued till the end of 2006 MAST: Experiments planned for 2006 TS: L-mode experiments Done NSTX: Experiments planned for 2006

Status of Contributions to CDB-4: Nov proposal, Jan, April Confinement scaling in ELMy H-modes: ν* scans at fixed n/n G Spokesperson: J. Snipes C-Mod: MP392 was approved for these experiments, and is expected to be scheduled in late 2005 or 2006. DIII-D: experiments may be attempted in 2006. AUG: await the outcome of PEP-7 (the pedestal identity experiment) and to assess afterwards if identity of ν* versus identity of n/n G can be separated given the error-bars - such experiments would not be done before 2007. DIII-D: not doing this year, but on the extended list for future work. C-Mod: Experiment now expected in 2006.

CDB-6: Improving the condition of Global DBs; Low A Spokesperson: S. Kaye MAST: 46 new data points we have been sent to the H-mode confinement database in March 2006. Factor of 1.8 I p scan in L-mode, with good density match, shows the I p exponent close to ITER L97 scaling. I p scan (0.7-1.2MA) in H-mode have been executed. The edge conditions appeared to be current dependent (ELMy at 0.7MA and ELM free at 1.2MA) and thus the scan is subject to colinearity between I p and n e. NSTX: Dedicated scaling experiments carried out in 2006 to isolate B T and I p dependences in H-mode plasmas, and found τ th ~ B T 0.9 I p 0.4 scaling. Dimensionless parameter scans carried out (ν *, β T ) and found Bt E ~ ν *-1.0 β T -0.1 for κ = 2.1 and δ = 0.6. MAST: 2007 planned improving the I p scaling, dimensionless β scaling, and effect of pellet fuelling. PINI neutral injector has been operational long pulses and power up to ~1MW, and now to increase the power further. NSTX: In 2007, attempt β scan at κ=1.7, δ=0.3 to assess dependence of degradation (or lack thereof) on shape. Density scaling at fixed q and power.

Status of Contributions to CDB-6: Nov proposal, Jan, April Improving the condition of Global DBs: Low A Spokesperson: S. Kaye MAST/NSTX: Identity experiments to confirm parametric confinement scalings at low A and understand the scaling of confinement with A by connecting to data from conventional and higher A tokamaks. Establish the scaling of confinement with both toroidal beta and collisionality in L and H- mode discharges. Eliminate the strong correlation between b and e in low aspect ratio data. Improve the condition of the database by the addition of low-β low A data, and low B T, high β data at conventional A. DIII-D/NSTX: Similarity experiment will focus on ensuring a similar fast ion fraction in the comparison discharges. The devices will individually perform a ρ* scan to determine scaling with toroidal ρ*. DIII-D: not doing this year, but on the extended list for future work. To be updated by S. Kaye

CDB-8: ρ* scaling along an ITER relevant path at both high and low β Spokesperson: D. McDonald In 2006, no results have been obtained, but both C-Mod and JET performed test shots to see if the required parameter range for the low β scan could be achieved. C-Mod: The natural plasma density in the C-Mod scenario was too high to match the ITER ν*. JET: Able to achieve the required parameter range at the tested I p = 2MA. C-Mod: Further test shots will be performed in Winter 2006, following the installation of the divertor cryopump, when it is hoped the required density will be achieved. JET: Part of the experiment is expected to be performed in Jan-Mar 2007. DIII-D: In 2007, planned as high priority experiment. Use our own version of ITER shape rather than wait for JET and C-Mod to complete their part of this joint experiment.

Status of Contributions to CDB-8: Nov proposal, Jan, April ρ* scaling along an ITER relevant path at both high and low β Spokesperson: D. McDonald JET/C-Mod: These devices lie at the extremes of ρ*, and will perform the low β experiments in February and March 2006, respectively. AUG/DIII-D: The high β part of the ρ* scan would be a hybrid scenario, which will be deferred until JET auxiliary power is increased and the hybrid scenario is more firmly established. JET: Experiments scheduled for June C-Mod: Experiments scheduled for May (need ICRF running well) DIII-D: Experiments with ITER shape scheduled for June

CDB-9: Density profiles at low collisionality Spokesperson: H. Weisen C-Mod: Produced low density, low collisionality H-modes (no NBI) for the first time by means of different shaping, demonstrating peaking in line with JET and AUG results. (M. Greenwald APS 2006) JT-60U: Experiments showed high peaking in electron heated experiments. Peaking larger than in JET, AUG, C-Mod! (Preliminary) Data was obtained in wide ranges of ν eff, T e /T i and particle source. Density peaking with low central fuelling and electron heating (EC+N-NB) is comparable to or even stronger than that with central fuelling and ion dominant heating (P-NB). JET, AUG: Planned experiments postponed to Nov.2006 and beyond. DIII-D: In 2007, planned as medium priority experiment. JT-60U: No experiment until October 2007. Analysis in lower ν eff regime. Joint Analysis Work Attempts using scalar database failed JET and AUG profile data combined into single database (~600 samples) Regression predicts peaking factor >1.4 in ITER (Submitted to NF, oral at IAEA FEC 21)

Status of Contributions to CDB-9: Nov proposal, Jan, April Density profiles at low collisionality Spokesperson: H. Weisen JET, JT-60U, AUG, DIII-D : Target conditions T i /T e ~1 and ν eff <0.2 at r/a~0.5 at moderate β N ~1.8, may require adjusting the heating because of poor equipartition at low ν. All: Provide scans to lowest achievable n even if the lowest target value (ν eff <0.2) cannot be achieved. Profiles of impurities should be examined in all cases. JET: Experiments at low ν with pellet injection ~June 2006 when injector is available. Notes: Experimental scans may be designed to also cover the information for CDB-4 (ν scan at fixed n/n G ), and TP-3.1 (T i /T e effects on confinement in hybrid scenarios) and SSO/TP- 2.1 (hybrid regime development). JET: Experiments planned for March & May 2006 on particle and impurity transport at low n as part of pre-existing proposals - not driven by T e ~T i. JT-60U: Experiments planned for 2006. T e ~T i may be too restrictive. AUG: Most effort on analysis of existing data and collaboration with JET. DIII-D: Not doing this year, but on the extended list for future work. Notes: Primary collaboration for this year is between JET (Weisen) and AUG (Angioni). Retain as P (programmatic) designation for this year. AUG: Experiments on peaking at low ν planned for late June (post EPS) C-Mod: Snipes working with Weisen to define experiments for 2006 JET: experiments planned for June and July 2006 (purpose shear dependence at low ν* and effect of electron heating in H-mode)