Summary Report for Joint
Modeling Activity on Steady State
Exploration – IOS-JA7
C. E. Kessel for P. T. Bonoli (MIT)
7th IOS Topical Group Meeting
Kyoto, Japan
October 18-21, 2011

IOS-JA7: Modeling of Steady State Scenarios•! Contributors: P. T. Bonoli (MIT), R. Budny, C. E. Kessel, F.
Poli (PPPL), G. Giruzzi, J. Garcia, F. Imbeaux (CEACadarache), A. Fukuyama (Kyoto U.), G. Batemann, A. H.
Kritz (Lehigh U.), M. Murakami, J. M. Park (GA), T. Oikawa(IO), V. Parail (JET), A. Polevoi (IO), A. Tuccillo, R. Cesario(Frascati)…….
•! Original Objectives: Analyze the current drive requirements
for steady state target discharges using both time dependentand stationary (in time) models:–! Determine combinations of NBI, ECRF, ICRF, and LHRF powers thatcan provide SS (100% non-inductive) current profile in combination
with BSCD.
–! Determine plasma configurations and their properties.
–! Determine requirements on actuators in terms of powers, combinations,and sensitivity for time dependent access to steady state target
discharges.

Feedback from IOS Group in Culham (April, 2011)•! Proposed Plans for 2011 at Culham Meeting were:–! Specify equilibrium and plasma profiles for SS targets.
–! Determine how different simulation models can be applied:•! Time dependent transport codes would be pre-programmed to evolve to the specifiedsteady state and then execute their actuators.

–! Produce first inter-model comparison for a specified actuator set.

•! But the IOS Group thought that goals needed to be further refined forthis joint modeling activity:–! Some specific worthwhile observations were:•! (Giruzzi) – use parallel computing capability to establish high physics fidelity
simulations that can be used as reference for “reduced” models.
•! (Hubbard) – fixing n(r, t) and T(r, t) focuses the modeling activity on
comparing actuators, which you may not want to do.
•! (Joffrin, Ide) – useful to perform sensitivity studies of various models variations
in plasma parameters and profiles.
•! (Kessel, Casper) – middle of the road approach, e.g. need to mind bothactuators and time dependent modeling.

•! “Steady state exploration” is actually composed of a number of criticalcomponents:–! Target relaxed flattop plasma configurations that obtain 100%
noninductive current and Q ~ 5….MHD stability, transport, and otherassessments–! Access to and feedback control of steady state ….
–! Sensitivity studies of actuators ….
–! Actuator requirements …..

Observations and plans for moving forward(Bonoli / Kessel)•! There has been a lack of progress in moving forward on the2011 goal of formulating a target case for inter-modelcomparison:–! Activity leader (Bonoli) has not had time to coordinate this.
–! IOS members are working on their own worthwhile SSE studies•! Poli / Kessel – SSE studies with TSC-TRANSP.
•! Batchelor / Bonoli – IPS and ACCOME ITER simulations.
•! Cronos Group – new SS scenario work within F4E Agreement.
•! Murakami / Park – ONETWO studies (just published a paper).
•! Casper / Kim – Corsica simulations and actuator upgrades•! Budny / Kritz – PTRANSP simulations•! Other Groups – (ASTRA, TASK ……)–! IOS members are also working on worthwhile actuator studies:•! LHRF – code comparisons, “density limit” studies, etc•! ICRF – code comparisons•! ECRF – launcher optimization studies•! NNBI -- benchmarking, studies of lower energy

Propose that IOS-JA7 be split into a two parts•! IOS JA7-A: Steady State Exploration (“SSE”) tobe spokespersoned by C. Kessel.
–! There are clearly several active groups that have the IMmodeling capability with varying sets of actuators toexplore access to SS ITER regimes that can contribute.

•! IOS JA7-B: Actuator Requirements andComparison (“ARC”) to be led by P. Bonoli.
–! There is still a clear need for NB, LHRF, ECRF, and
LHRF actuator studies and these could be presented andvetted here, particularly within the context of the timedependent SSE studies.

Specific Example of a Work Plan and Commitment•! IOS-JA7-A: (SSE)–! Murakami/Park SS configuration existing–! Garcia/Giruzzi SS configuration existing–! Kessel/Poli defining SS cases with mixtures of actuators from their
TSC-TRANSP studies (see Poli /Kessel talk at this meeting).
–! Others producing SS configurations•! IOS-JA7-B: (ARC)–! Bonoli/Batchelor will commit to simulating one or more of Kessel/
Poli cases with the Integrated Plasma Simulator (IPS), because
they use the same transport code, in order to test high fidelity
models (or resolution) against reduced models•! Sensitivity of NBI results to Monte Carlo particle statistics.
•! Refinement of internal TSC model for ICRF heating and FWCD using IPSTORIC & AORSA simulations at low and high spectral resolution.
•! Comparison of LHCD from TSC-LSC with predictions from the IPS using
GENRAY / CQL3D.
•! Refinement of internal TSC model for ECCD using the IPS with GENRAY /CQL3D.

–! Comparisons by other groups with reduced and high fidelity
models (CRONOS, TASK, GA,……)Status of activities reported bymembers•! Contribution from Poli/Kessel on SSE•! Summary from R. Cesario on LH actuators

Five H/CD combinations, IP=7-10 MA (100% non-inductive)
73 MW

20 MW EC + 20 MW IC
20 MW EC + 20 MW LH

93 MW

40 MW EC + 20 MW IC
40 MW LH + 20 MW IC

68 MW = 40 MW LH + 20 MW IC(F. Poli, C. Kessel - PPPL)+33 MW NB

electron density [x10+ 8 MW NB20 −3

152% Be , 0.4% Ar10Pcore, rad = 25-35 MW(brem+cyc+line)
50.4

ρ

0.6

0.8

135(a)

30

0.7

R=6.2, a=2.0. k=1.8, d~0.45
IP = 7-10 MA
n/nGr ~ 0.75-1.0
100% non-inductive current
n(0)/<n> = 1.0-1.5m ]electronEPED1
density [x10estimate:temperature (keV)(P.electronSnyder)3510(b) 3 0.8(a)19
Tped ~ 3.3-3.7 keV30@ nped = 5-6.7x10 /m
0.7 825
rped ~0.94
0.6206Impurities and radiatedpower0.50.2m ]0.8

Target plasma:

31001
32001
33001
34001
35001

20 −3000.2

0.4

ρ

0.6

0.8

0.6

0.30.2[x10electronsafetydensity
factor100

20 −3m ]31001 (IC+20MW EC)
32001 (IC+40MW EC)
33001 (EC+LH)
34001 (IC+LH+33MW NB)
35001 (IC+LH+8MW NB)

(a)
(c)

0350.2

ρρ

0.6

0.8

30

1020

11001864

31001
32001
33001
34001
35001

50.8
0.8

0.4(b)

100.6
0.65ρ
electron temperature(keV)

150.40.4

1025

31001
32001
33001
34001
35001

0.2
0.21531001
32001
33001
34001
35001

0.4

0.30.2 2200.5

0.4 4

31001
32001
33001
34001
35001

2500.2

0.42

ρ

0.6

0.8

100

Find operational space stable to ideal MHD•!

Use TSC/TRANSP•!

H/CD settings to maximize performance•!

NB: off-axis steering, peaked at r=0.35•!

•!

IC : 48 MHz, on-axis deposition=>
200-400 kA FWCD
EC : midplane launchers, r=0.35=>
IECCD~0.7 MA (1.4 MA)
LH : n||=2.15, !n||=0.2, (rLH~0.65) P+ = 85%, P- = 15% => ILH~0.8 MA•!
•!

Use H98 ~ 1.6 as target
Prescribe the " to produce an ITB and scale to provide H98•!

3.5(a)

ballooning
unstable

IC+20MW EC
IC+40MW EC
EC+LH
IC+LH (8MW NB)

kink unstable

IC+LH (16MW NB)
IC+LH (33MW NB)

βN

N(b)
Analyzed ideal MHD stability in the flattop for variationsof•! Greenwald
fraction (within 1.15 of nG)
33•! Pressure peaking factor
2.5stable operational space•! Find2.5
bN, q, li, p(0)/<p>
scenarios with LH

β•!

3.5=> ~3 MA of CD

22scenarios with IC+EC

1.50.5

1

1.5
qmin

2

2.5

1.5
2.2stable

2.4

2.6
p(0)/<p>

2.8

39

Current Status of Modeling Activities – LH Actuator – (R. Cesario)•! Studying use of lower hybrid on steady state discharges in ITER (R.
Cesario et al., EPS 2006, EPS 2008, RF conf Gent 2009; Nature Comm.
1(5) 55, 2010, PPCF 53 (2011) 085011):–! LHstar code used, for ray-tracing+FP modeling including the effect of nonlinear physics of the edge (spectral broadening produced by parametricinstability (PI)).
–! Considering the SOL available data expected for ITER (Te<100eV at r/a=1.007- 1.10 ), a very external deposition of LH power is expected: see results at thismeeting from A. Tuccillo.
–! The lack of LH power penetration in the core of JET AT exps. with ITERrelevant ne profile has been interpreted as due to strong PI spectral broadening
at the edge. Strong single pass LH absorption at high T (Te0! 6 keV) prevents
collisional damping playing a dominant role.

•! Study of LH penetration across steep density gradient (A. Cardinali and F.
Santini, Plasma Phys. Contr. Fusion 53 2011):–! In the JET AT exps. with ITER-relevant ne profile with steep gradient and no
LH effects, ray deviation effects are negligible.

•! Study of parasitic absorption of LH waves on fusion alpha-particles (E.
Barbato and A. Saveliev 2004 Plasma Phys. Contr. Fusion 46 1283):–! f ~ 5Ghz absorption on alphas is below 2% in the Q=5 scenario–! At worst, 8% in the Q=10 scenario.

•! Additional research on mechanisms for possible LH dissipation atperiphery are also being studied:–! Paper submitted to NF by Pericoli on Wave Scattering by Density Fluctuations.
–! Paper accepted for publication in NF by Barbato on Collisional absorption.