TORIC/TRANSP simulations of ICRH heating of JET plasmas

TRANSP user meeting, JET, 11/01/2008

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TORIC/TRANSP simulations of ICRH heating of JET plasmas

Summary of TORIC runs for JET (I. Voitsekhovitch) and discussion with TRANSP and ICRH experts (Yu. Baranov, J. Conboy, I. Jenkins,

T. Johnson, D. Keeling, E. Lerche)

Outline

1. Brief information about TORIC

2. TORIC namelist in TRANSP and TORIC related post-processing

3. Benchmarking of old and new TORIC versions

4. Benchmarking between TORIC and SPRUCE for minority heating

5. Fundamental D heating with TORIC

6. Mode Conversion simulations: comparison with TOMCAT & PION


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What is TORIC?

TORIC is a FLR full wave code. It solves Maxwell’s equations in the presence of plasma and wave antenna. It does this with a fixed frequency and a linear plasma

response in a mixed spectral-finite element basis. The oscillating plasma current JP is considered as a moment of the perturbed particle distribution from the linearised

Boltzmann eq. in the presence of the electric field from the excited wave.

AP JJ

iE

cE

4

2

2

inimEE nm exp)(,

TORIC uses the FLR expansion to convert the vector integro-differential Maxwell equation with d/dt -i into a 6-order partial differential equation. This

approximation retains the 2nd harmonic wave frequency and is 2nd order in i.

)(),()( // mm

mPm EkJ

B

B

R

n

B

B

r

mk //

TORIC works in combination with FP models (FPPMOD, SSFPQL, CQL3D).

Refs: M. Brambilla, PPCF 41, 1, (1999) & M. Brambilla and T. Krucken, NF 28, 1813 (1988); D. G. Swanson, Phys. Fluids 24, 2035 (1981); P. T. Colestock and R. J. Kashuba, NF 23 763 (1983); J. C. Wright et al,

PoP 11, 2473 (2004)


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TORIC namelist in TRANSP

NICRF=8 ! ICRF model switch (1=new SPRUCE; 5=old SPRUCE, 8=TORIC)...NMDTORIC=31 ! N of poloidal modes: Npol = 2n-1, Npol is calculated for given nRFARTR=5.0 ! distance from antenna to Faraday shield, cmANTLCTR=1.6 ! effective antenna propagation constantNFLRTR=1 ! ion FLR contributions, =1 included, =0 ignored! NFLRETR=1 ! electron FLR contribution, was commented in RB namelist! FLRFACTR=1.0 ! was commented in RB namelistNBPOLTR=1 ! poloidal magn. field, =1 included, =0 ignoredNQTORTR=1 ! toroidal broadenning of plasma dispersionNCOLLTR=0 ! collisional contribution ENHCOLTR=1.0 ! electron collision enhancement factor! ALFVNTR(20) ad hoc collisional broadenning of Alfven and ion-ion resonanceALFVNTR(1)=0.0 ! =1 included, =0 ignoredALFVNTR(2)=0.1 ! enhancement factorALFVNTR(3)=3.0 ! value of abs((n//^2-S)/R) below which damping is addedALFVNTR(4)=5.0 ! value of abs(w/(k//*v_te)) below which damping is calculated

! needed to maintain reasonable values of RF current

Suggested by Robert Budny, the convergency of simulations with this namelist for JET shot has been examined by MIT TORIC experts

TORIC documentation: http://www.jet.efda.org/expert/transp/Toric/Manual/frame.htm

Parameter variations for 66316 (H minority): RFARTR = 2 - 5, ANTLCTR = 1-1.6, ALFVNTR(1) = 0 - 1, ALFVNTR(3) = 3 - 10 no effect on ICRH deposition


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Post-processing:The ICRH power deposition is transferred from TORIC to TRANSP by default. For more

detailed information at given time steps (resonance positions and heating of different species for each antenna separately, wave fields, etc.) the following lines should be

added to the namelist:

FI_OUTTIM(1) = T1 ! T1 [s] is the time for first outputFI_OUTTIM(2) = T2 ! T2 [s] is the time for second output etc. TMAX=9

Detailed results obtained with TORIC are saved in Imp.tgz file.Steps to extract the TORIC data:tar –xz –f Imp.tgz (extracts the files shot#runID_FI_TAR.GZ1 (2,3,etc.) & shot#runID_ICRF_TAR.GZ1 (2,3,etc.)) fi_gzn_unpack

(creates directories shot#runID_fi & shot#runID_icrf. The shot#runID_icrf directory contains the files shot#runID_A#_n-1Ntor_toric5.msgs (fppdata, etc.), input equilibrium and plasma profiles. The routines gfpprf and xfpprf can be used to look at stored results)


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Toric 4 / 5.2 Comparisons

• Toric 4.0 has been available for use with TRANSP for some years• The latest Toric 5.2 code was obtained from Garching, and

substituted for version 4 at the end of 2007. Regression testing uncovered a couple of bugs in the new code

• The current drive normalisation differs by 25% between Torics 4 & 5.2 ; it is still unclear which version is correct.

• These differences raise doubts about the effectiveness of any regression testing of the latest version of the code, prior to its release ( see also http://www.jet.efda.org/expert/transp/Toric/index.htm).

• If the code is to play a significant role in analysis of the new ITER antenna at JET, then in house support by local ICRH experts will be required.


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JET scenarios selected for benchmarking

1. H minority heating (66316): BT = 2.6 T, Ipl

= 2.6 MA, nl 2e19 m-3, Te0 4.8 keV

2. He3 minority heating in RS ITB plasma (69407): BT = 3.45 T, Ipl = 2.5 MA, nl < 2.6e19 m-3, Te0 6.5 keV

3. Fundamental D heating (68731): BT = 3.3 T, Ipl = 2 MA, nl 2.5e19 m-3

4. Mode Conversion, He3 minority, ITB (62077): BT = 3.25 T, Ipl = 2.6 MA, nl < 3e19 m-3

66316

69407

68731

62077

ICRH

NBI

ICRH

NBILHCD

NBI

LHCDLHCD

ICRH

ICRH

NBI


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Benchmarking of old (TORIC/TRANSP) and new (TORIC/TRANSP) versions for H minority heating

- Total electron and ion heating power in perfect agreement;

- Strong disagreement for ICRH electron heating profile;

- It comes from disagreement from power absorbed by minorities

Pe at 6 s

Pe at 7.4 s

Pi at 6 s

Pi at 7.4 s

ICRH electron and ion power depositions

Wave power deposition on

minority

Power from minority to

electrons


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Problem with resonance locations (ex. for 66316)Wave frequency of A2/A3/A4 = 46.16/46.7/ 46.52 Mhz

From *****_toric5.msgs filesMain D:A2: Fundam. resonance at X = -168.291 cm - outside the plasma on the HFS Harmonic resonance at X = -40.572 cm tangent to the surface r/a = 0.52 on the HFSBeam D:A2: Fundam. resonance at X = -168.291 cm - outside the plasma on the HFS Harmonic resonance at X = -40.572 cm tangent to the surface r/a = 0.52 on the HFSC impurity:A2: Fundam. resonance at X = -168.291 cm - outside the plasma on the HFS Harmonic resonance at X = -40.572 cm tangent to the surface r/a = 0.52 on the HFS

… similar for A3 and A4H minority:A2: Fundam. resonance at X = -40.572 cm tangent to the surface r/a = 0.520 on the HFS Harmonic resonance at X = 224.605 cm - outside the plasma on the LFSA3: Fundam. resonance at X = -43.822 cm tangent to the surface r/a = 0.553 on the HFS Harmonic resonance at X = 218.536 cm - outside the plasma on the LFSA4: Fundam. resonance at X = -42.743 cm tangent to the surface r/a = 0.542 on the HFS Harmonic resonance at X = 220.547 cm - outside the plasma on the LFS

From *****tr.log file (simple estimation w/o Doppler shift):Antenna # 2: D harmonic 2 at R= 333.7 cm, D_MCfi harmonic 2 at R= 333.7 cm, C12_6 harmonic 2 at R= 333.7 cm, H_mino harmonic 1 at R= 333.7 cm.

Antenna # 3: D harmonic 2 at R= 336.6 cm, D_MCfi harmonic 2 at R= 336.6 cm, C12_6 harmonic 2 at R= 336.6 cm, H_mino harmonic 1 at R= 336.6 cm.

Antenna # 4: D harmonic 2 at R= 335.6 cm, D_MCfi harmonic 2 at R= 335.6 cm, C12_6 harmonic 2 at R= 335.6 cm, H_mino harmonic 1 at R= 335.6 cm.


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Benchmarking of old (TORIC/TRANSP) and new (TORIC/TRANSP) versions for He3 minority heating

TotalDirect electron heating

Direct ion heating

Minority heating

Electron heating

profile at 7 s

Ion heating profile at 7 s

- disagreement for total electron, ion and minority heating power as well as in Pe & Pi deposition profiles;

- discrepancy comes from different power absorbed on minority (like for 66316)

However, there is perfect agreement for 68731 (fund. D heating) where minorities

are not involved

Fund. He3 resonance at r/a=0.15 HFS (msgs)


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Effect of re-normalisation of quasi-linear operator (QLO) on power deposition for minority heating

- ICRF wave codes specify both the damping power density on minority fast ions, and the 2D wave field (E+, polarization, k, kll). In theory, the QLO coefficients are fully determined by the

wave field alone.

- Because of differences in the representation of fast ion distribution between the FP model and wave code, the damping power implied by QLO from the wave field alone may not match the damping power expected by the wave code, and the integrated profile will not match the power-at-the-antenna that was specified to wave

code.

- FPPMOD operator re-normalises the original QL operator zone by zone while keeping the total power constant. Low and upper limits of normalisation constant are fixed in TRANSP. When the normalisation constant exceeds one of these limits it will be restricted by this limit, but then the power should be re-distributed along the radius to have the same total power. This creates the distortion of deposition profiles and shift of the maximum absorbed power with respect to real resonance location.

old TORIC/TRANSP

new TORIC/TRANSP

PWAVEMIN (red) – power damped on minority calculated by TORIC; PQSLMIN (blue) – power

obtained with non-normalised QLO in TRANSP; PQLNORM – power damped on minority after the

normalisation of QLO (scaled by

PWAVEMIN/PQSLMIN)


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Update of FPPMOD routine

Warning: user should check the normalisation of QLO (gfpprf xfpprf (last plot) or multigraph RFHMIN_H (or _HE)) and compare original profile of TORIC wave power deposited on minority, non-normalised QL operator profile and normalised QL operator by TRANSP FP module fppmod. The profiles FWAVMIN and FQLNORM should coincide.

Immediate action: Doug added the minimum and maximum renormalization factors "min_qlnorm" and "max_qlnorm" in the FPPMOD namelist and raised the upper limit on the QL re-normalisation from 3 to 20.

To change these in the FPPMOD namelist when running xfpprf from data saved with FI_OUTTIM(...): in addition to the values themselves one have to set

mstate=1to prevent the namelist changes from being overwritten by the "state file" which is used when

xfpprf is run in this mode.

Long-term action: include the limits for the normalisation constants in the TRANSP namelist


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Benchmarking between TORIC and SPRUCE for H minority heating

This benchmarking has been done with the same TRANSP version switching from SPRUCE to TORIC

Direct electron heating

Power to fast ions

Direct ion heating

Total power

Power to minority

Evolution of total powers Power deposition at 6.6 s

Total absorbed

powerDirect electron

heating

Direct ion heating

Minority heating

Electron heating from minority

Ion heating from minority


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Different power deposition in all channels different

electron and ion heating power profiles

TORIC

TORIC

SPRUCE

SPRUCE

Electron heating power profile

Ion heating power profile

QLO

TORIC

6.6 s

SPRUCE


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Benchmarking between TORIC and SPRUCE for He3 minority heating (I)

Total


Direct ion heating

Minority heating

Evolution of total powers Power deposition at 7.5 s

Total absorbed

power


Direct ion heating

Minority heating

Electron heating from minority

Ion heating from minority


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Electron heating power profile

Benchmarking between TORIC and SPRUCE for He3 minority heating (II)

Ion heating power profile

TORIC

TORIC

SPRUCE

SPRUCE


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Fundamental D heating with TORIC (I)

Evolution of powers

Total

Direct ion heating


Fast ion

Power deposition at 7.5 s

Total

Direct electron

Fast ion

Direct ion

Minority

Minority electrons

Minority ions


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Fundamental D heating with TORIC (II)


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Mode Conversion case (62077) can be compared with TOMCAT [P. Mantica et al, PRL March 2006]

Direct electron heating (FW)

Minority heating

Minority to electrons

Minority to ions

Fast ion & direct thermal ion heating

Smaller time step should be used

TORIC does not show mode conversion number of poloidal modes should be strongly increased


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Effect of the number of poloidal mode: deposition profiles at minimum (red & pink) and maximum (blue & green) modulation amplitude obtained with NMDTORIC=31

(red & blue) and NMDTORIC=63 (pink & green)

Total absorbed power


Fast ion heating (small)

Direct ion heating

Minority heating

Minority to electrons

Minority to ions

- The results are weakly affected by the choice of poloidal modes;

- Modulation affects direct electron and minority heating, but not the power given to electrons and ions from minority. Finally, only central electron heating is modulated


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Electron and ion heating profiles at minimum (red & pink) and maximum (blue & green) modulation amplitude obtained with NMDTORIC=31 (red & blue) and

NMDTORIC=63 (pink & green)


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Summary of simulation results and discussion

• Effect of inaccurate re-normalisation of QLO has been found and re-normalisation has been improved, but users should always check the re-normalisation

• There is still a problem with resonance locations in *****.msgs file

• These problems were not seen in Cmod test case JET discharges contributed to regression test

• Large difference between TORIC and SPRUCE for minority heating case: negligible direct ion heating with TORIC (heating on second harmonic is not taken into account?), different heating profiles. Large and very localised central electron heating is not clear in ITB discharge. Benchmarking of SPRUCE and TORIC with the same number of modes is suggested.

• Fundamental heating – edge absorption? More shots with proper antenna frequencies should be tested. The study of this scenario by Ernesto shows that mainly beam ions are heated by ICRH.

• Mode Conversion – qualitatively in agreement with TOMCAT & PION, but wrong resonance location in *****.msgs file and no MC. Suggestion of ICRH experts: much larger number of poloidal modes (at least 200) should be used.


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Conclusion of TRANSP and ICRH experts:

TORIC does not provide an ‘off the shelf’ solution to analysing JET RF pulses. At present we cannot explain or solve the problems found in TORIC simulations of JET plasmas, or the observed differences between the ICRH codes

In the opinion of those present, development of ICRH modelling for JET will require the full time attention of an ICRH expert.

Documents

TORIC/TRANSP simulations of ICRH heating of JET plasmas