1 ITPA-IOS meeting, October 2011J. Stober ITPA-IOS Meeting Kyoto 10/2011 Report from ASDEX Upgrade...

1 ITPA-IOS meeting, October 2011 J. Stober

ITPA-IOS Meeting Kyoto 10/2011Report from ASDEX Upgrade

Reported by Jörg Stober for the AUG Team


Topics

selected results of the last campaign, related to IOS- RMP-coils

- N2-seeding : high power, q95 = 3

- O1 heating of H-modes- improved H-mode (advanced inductive)

Issues related to JE, not reported elsewhere

4.3 nu* scann: plans for next year

5.2 ICRH

Next campaign: time line and hardware modifications


RMP-coils (Next slides from W. Suttrop, ITPA-PEP)

Operation Jan - Jul 2011:2×4 B-coils (upper and lower rows)n = 2 ELM mitigationn = 1 Error field measurement

Shutdown Aug-Dec 2011Installation of additional 8 upper/lower B-coils

Operation Jan 2012 -n = 0, odd/even up/down parityn = 2, row phasing 0,90,180,270 degreesn = 4, odd/even up/down parity

Power supplies:— Currently 2 circuits with grid-commutated2-quadrant converters fmax 20 Hz.— Seeking solution for 4 independent4-quadrant amplifiers (±1 kA into 500 μH)(n = 3, rotating fields)

Full in-vessel coil set:3 rows, each with 8 saddle coils

W Suttrop et al, Fus. Eng. Des. 84 (2009) 209


RMP-coils : no ELMs triggered with pellet fuelling

P. Lang


RMP-coils : central densities of 1.6 nGW

selected


RMP-coils : no density dependence of E


RMP-coils : DIII-D low-* mitigation not reproduced

selected

W.Suttrop, T.Evans


RMP-coils : comparison with DIII-D ongoing

selected


RMP-coils : summary


High power seeding with peak heatload < 5 MW/m2High power seeding with peak heatload < 5 MW/m2

Peak load < 5 MW/m2 !

Combined strong D divertor puff, feedback controlled N divertor seeding (q95=3.7, u=0.1, l=0.43)Modelling with B2-Eirene about to start

IOS 1.2, A. Kallenbach


q95 = 3 with N2 seeding

Ip (MA)

H-factor

ne

N

Wmhd

PECRH,X3

TS

core

edge

Te

MP-coils

snif

Te,div

N2

PNBI, Prad

Ptot

D2

IR-Power Div o i

#26870


O1-heating of H-modes : polarisation control

105 105 GHzGHzBBtt= 3.2 = 3.2 TT

„„wrongwrong““X-modeX-modedirectlydirectlyreflectereflectedd

O1 X1

X-modecut-off

1st harmRes


O1-heating of H-modes : polarisation control

150

160

170

50 60 70 80

Power X-mode

2 %

4 %

/ 8

/ 4

0

2

4

6

8

160 165 170

Power X-mode (%)

1

2

3

4

5Sniffer signal (V)

0

2

4

6

8

10

1.5 2.0 2.5

time (s)158 167

With 1% X-mode content, switch-off level is already exceeded(preliminary, orthogonal scan still to be done)

H-mode, 1 MA, -3.2 T, 105 GHz, #26864


O1-heating of H-modes: effect of UHR

V. Vdovin finds significant effect of UHR for O1 scenariowith full wave code.

Does he predict measurable effects for AUG ?

These could be verified using modulated ECRH and X2-ECE.

Preparation on AUG: finalize polarisation control such thatX2-ECE can be used (up to 188 GHz)

AUG-proposal submitted for 2012co-authors: V. Vdovin, R. Prater


Access to improved H-mode (advanced inductive)


Improved H-mode: current overshoot

selected

(J. Hobirk, EPS 2011)

Pulse very similar Slightly less gas and lowertarget density for heating NBI heating increased to 10MW

Small differences in density and power waveforms can lead to significant improvement on AUG

βN=4.5 and confinement equivalent to H

98y2>2 reached

terminated by strong n=1 mode Extended ELM-free phase before crash Also radiation increases strongly before crash

(Slide from EPS 2011 talk J. Hobirk)


Improved H-mode: recovery of the pre-W scheme

#20993 : year 2006ICRH limiters still graphite

#27056 : year 2011All tungsten?? days after boronization

Major differences- replace ICRH by ECRH- wave form gas puff

Already quite close butramp-up and H-factornot fully recovered

Ip

ncore

nedge

Ptot

PRF

H98

WMHD

0,div

0,main

D2 puff

Te0, Ti0


IOS 4.3 : nu* scaling of advanced inductive Szenario

No dedicated discharges in 2011: try to learn from rho* scan

Scaling: I2 = c I1, B2 = c B1, T2 = c2 T1, n2 = n1 *2 = c -4 *1

minimum sensible c = 1.2 yields factor 2 in *

Problem (in AUG): n/nGW varies as 1/c, how wide can it be varied?

Try to connect to rho* experiment (see C. Challis for JE 4.2),

including attempts to rise density.


Gas puff scan in rho*-scan shape and q95

rho*-scan lowest density attempt to increase density

H98Wmhd

Ip

Gas

ncore

nedge

H

PNBI

PECRH

Te#27224 #27052


Density profile can only be varied by 1.12

#27224

#27052scaled

both @ 2.6s

So far, good match of shape


ECRH scheme used : compensated toroidal lauch

pECRH

jECCD


Torbeam: Poor absorption for n2 = 1.15 n1


Proposed solution: increase q95, Bt by 5%

Allows smaller tor. injection angle, simulation with n = 1.2 nrho*


The high Ip, Bt case can be heated on low field side


Reasonable agreement of ECRH power deposition

rho* case, #27224q95 = 4.2Bt = 2.26 TIp = 0.93 MAne0 = 8.6 x 1019 m -3

high * caseq95 = 4.4Bt = 2.37 TIp = 0.93 MAne0 = 10.3 x 1019 m -3

low * caseq95 = 4.4Bt = 2.85 TIp = 1.12 MAne0 = 10.3 x 1019 m -3


IOS-4.3 : AUG-Proposal for 2012

- repeat rho* pulse with 5% higher Bt and modified ECRH angles- increase density by 20%- increase Bt and Ip by 20%- adjust gas puff and power to match scaling requirements

5-10 shots depending on number of iterations

May still be modified after this meeting


IOS-5.2 : ICRH gas puff

Old results: if gas injected locally, antenna loading is significantly higher (doubled in our case) [Ph. Jacquet, V. Bobkov et al., to be submitted to NF]

No experiments done in 2011: restrictions in infrastructure of antenna gas injection which was transfered to another antenna

Increase of AUG ICRF antenna loading by local gas injection

2012: new infrastructure, measure the local effect in large type I-ELMy plasmas, check loading depence on RF power at low power

V. Bobkov


AUG : Hardware upgrades and time line 2012

- Number of RMP coils doubled, allows n=4 perturbation

- Power supplies to rotate perturbation delayed (no pref. funding)

- Design of 8 mid-plane coils ready, but no preferential EU funding

- Limiters of ICRH antenae will be partially boron-coated

- New antenna design with reduced stray field ready, Financing unclear, coop with Italy and/or China

- 1 additional ECRH unit (1 MW) in spring 2012 Total power in plasma at 140 GHz close to 5 MW

Restart January 2012End of campaign November 2012

6 weeks without operation in August / September


AUG : ICRH Upgrades

After 2012: two new 3-strap antennas for better compatibility with W wall

2012: two antennas with B-coated side limiters to make operation easier

(V. Bobkov et al.)

1 ITPA-IOS meeting, October 2011J. Stober ITPA-IOS Meeting Kyoto 10/2011 Report from ASDEX Upgrade...

Documents

Transcript of 1 ITPA-IOS meeting, October 2011J. Stober ITPA-IOS Meeting Kyoto 10/2011 Report from ASDEX Upgrade...