April 8-12 20031TTF, Madison/ 4th ITPA St Petersburg Clarisse Bourdelle Association EURATOM-CEA First results using kinezero because faster, and also not

April 8-12 2003 1TTF, Madison/ 4th ITPA St Petersburg Clarisse Bourdelle

AssociationEURATOM-CEA

First results using kinezero because faster, and also not enough

time yet to check the input file maker for GS2• Kinezero:

– gyrokinetic, local, eigenvalue

– ion and electron, passing and trapped

– electrostatic, collionless, s- geometry, linear

fast: ~150 in 1 hour on 1 CPU

allows to scan extensively parameter fields

C. Bourdelle, X. Garbet, G. T. Hoang et al , Nuclear Fusion 42 (2002)



First line of attack:study impact of in ITBs, in particular ITBs with

high gradPWhy is particularly interesting?

• High lowers vertical drift, therefore lowers dominant interchange instability

• As is increased the confinement improves, the pressure peaks, leading to even higher : possibility for positive feedback, like for ExB stabilization

• Unlike ExB stabilization, no need for external momentum input: relevant for reactor scales



JT60-U #39056 at 6.8 s and at the barrier location, gradP is high enough to be at threshold for positive

feedback between and gradP

gradP * 16!

a high q (high ) is necessary tohave below ExBbut only an increase of through gradP leads to have a complete stabilization



Growth rates very sensitive to input profiles…

• Here we see that a slight change of s (from 0.4 to 0.6) leads to higher than ExB

• As well for slightly lower or higher gradP (/2 or *2) would lead to lower

• So it is very important to put very carefully checked profiles in the database to allow for relevent microstability analysis



In JET ITB, is stabilizing inside barrierA lower q would be destabilizing at barrier

for ITG-TEM and ETG

negligible impact of s < 0



JET : versus for reversed (#53521) and monotonic (#46664) q-profiles

qx2#53521 at 6s #46664 at 6s



sstable

unstable

stable0ITB triggered by s < 0 ?

For example, a question that would be nice to try further to answer using the ITPA database:

Is it possible to sustain ITB without ExB shear, just with stabilization?

ITB triggered by high (high q) ?



General remarks about the use of the ITPA profile database from C. Bourdelle

• I regret that the scenarios are not understandable from data in the database, for e.g. DIIID #87031 is only for 500ms, and #95989 for 600ms. Need to include scenarios in comments or with 1D data.

• Raw data for direct comparison experiments versus modelling (instead of comparing to already smoothed data) and a better understanding of the scenario

• Miss JT60-U data on the UK web site. Could not access the data despite going through recognised IP #

• UK site well documented. Should add any «private» tools, as Colin started to do. Colin developed an IDL tool to prepare GS2 input files. I am planning to add a tool to prepare KINEZERO input files and to convert the IDL get_profile in matlab.

• Different q-profiles obtained by TRANSP ( ITB database) and CRONOS particular JET #53521

Documents

April 8-12 20031TTF, Madison/ 4th ITPA St Petersburg Clarisse Bourdelle Association EURATOM-CEA First results using kinezero because faster, and also not