/
Multiple NTM modes in experiment Multiple NTM modes in experiment

Multiple NTM modes in experiment - PowerPoint Presentation

lindy-dunigan
lindy-dunigan . @lindy-dunigan
Follow
408 views
Uploaded On 2016-02-26

Multiple NTM modes in experiment - PPT Presentation

and nonlinear coupling O Sauter Ecole Polytechnique Fédérale de Lausanne EPFL Swiss Plasma Center SPC Lausanne Switzerland httpinfoscienceepflchrecord212765 Outline Several ID: 232122

mode coupling jet modes coupling mode modes jet effects power epfl preemption plasma 2002 ppcf tcv increasing 2015 2003

Share:

Link:

Embed:


Presentation Transcript

Slide1

Multiple NTM modes in experiment and nonlinear coupling

O. SauterEcole Polytechnique Fédérale de Lausanne (EPFL)Swiss Plasma Center (SPC)Lausanne, Switzerlandhttp://infoscience.epfl.ch/record/212765Slide2

Outline

Several cases, mainly taken from published dataCoupling (locked frequencies

)

can

have

little

effects

or

stabilizating

effects

No «

dramatic

»

effects

observed

so

far…Slide3

«Standard» case when

increasing powerR. Buttery, Nucl. Fus. 43 (2003) 69, JETIncreasing power4/3 appearsThen 3/2Finally 2/1, which locks «whole» plasma(E. Lazzaro, PoP 9 (2002) 3907)Slide4

«Standard» case when

increasing powerDIII-D/JET similaritiesAt 2/1 onset, little change of 3/2, which continues.T. Hender et al, IAEA 2002, JET

While

2/1 locks, 3/2

can

lock to 2/1

with

little

effectsSlide5

Large trigger can

yield several modesR. Buttery, IAEA 2004, JET3 modes triggered together2/1 leads the lockingTermination seems similar to when only 2/1 mode presentSlide6

TCVSlide7

Non-harmonic

couplingD. Raju, PPCF 45 (2003) 369Slide8

4/3 effect on 3/2 mode

D. Raju, PPCF 45 (2003) 369Slide9

4/3 effect

on 3/2 mode=> constant D’coupling<0O. Sauter, PPCF 44 (2002) 19992 consecutive ST crashestrigger and stabilize 4/33/2 evolution consistentwith a constant negativeD’ in modif. Ruth eq.

JETSlide10

3/2 preemption

may also help for 2/1 preemptionD. Kim, PhD thesis No 6539, EPFL, 20152/1 mode avoided with 3/2 preemption: preliminary resultsMay indicate coupling, marginal conditions, q profile changes: to checkDifficult to trigger 2/1 without first a 3/2 mode…

TCVSlide11

Changing q profile does

play a roleE. Lazzaro, Nucl. Fusion 55 (2015) 093031D. Kim, PhD thesis No 6539, EPFL, 2015Same power ramp but different co/cnt components of beamsOnset at different power levels3/2 mode contribution

before

2/1

onset

is

different

as

well

TCVSlide12

Some conclusions

Multiple modes can co-exist without coupling (most cases)Usually the mode with larger r(q=m/n) dominatesMode can couple: best analysis is bi-coherenceNeed to check exact frequency couplingNeed to check effective effects on island widths(t) (nonlinear/frequency

coupling

does

not

necessarily

mean

«

strong

»

coupling

)

Word of caution: 2/1 modes tend to

kill

rotation over whole plasma thus all modes "will" «lock» during the process

Role if any of 3/2 preemption on 2/1 avoidance may provide more insight