Advances in sawtooth control for NTM prevention in JET · Sawtooth control in JET S. Coda, MHD...
Transcript of Advances in sawtooth control for NTM prevention in JET · Sawtooth control in JET S. Coda, MHD...
![Page 1: Advances in sawtooth control for NTM prevention in JET · Sawtooth control in JET S. Coda, MHD workshop, PPPL, 22 Nov. 2004 Long sawteeth trigger (3,2) NTMs at low β N O. Sauter](https://reader036.fdocuments.net/reader036/viewer/2022070718/5ede0b2dad6a402d66694f8c/html5/thumbnails/1.jpg)
S. Coda, MHD workshop, PPPL, 22 Nov. 2004S. Coda, MHD workshop, PPPL, 22 Nov. 2004
Advances in sawtooth controlfor NTM prevention in JET
S. Coda1, L.-G. Eriksson2, J. Graves1, R. Koslowski3,F. Nave4, P. Belo4, R.J. Buttery5, S. Cowley6,
P. de Vries5,7, M.J. Mantsinen8, M.-L. Mayoral5,A. Mück1, O. Sauter1, E. Westerhof7,
and JET-EFDA contributors
1CRPP, EPFL, Association Euratom-Fédération Suisse, Lausanne, Switzerland2Association Euratom-CEA, DRFC, Cadarache, France3Association Euratom-FZ Jülich, Institut für Plasmaphysik, TEC, Jülich, Germany4Associação Euratom-IST, Centro de Fusão Nuclear, Lisbon, Portugal5Euratom-UKAEA Fusion Association, Culham Science Center, United Kingdom6Department of Physics, Imperial College, London, United Kingdom7Association Euratom-FOM, FOM-Rijnhuizen, TEC, Nieuwegein, The Netherlands8Association Euratom-Tekes, Helsinki University of Technology, Finland
![Page 2: Advances in sawtooth control for NTM prevention in JET · Sawtooth control in JET S. Coda, MHD workshop, PPPL, 22 Nov. 2004 Long sawteeth trigger (3,2) NTMs at low β N O. Sauter](https://reader036.fdocuments.net/reader036/viewer/2022070718/5ede0b2dad6a402d66694f8c/html5/thumbnails/2.jpg)
S. Coda, MHD workshop, PPPL, 22 Nov. 2004Sawtooth control in JET
Outline
• NTM triggering by long sawteeth
• Sawtooth destabilization by ICCD
• Sawtooth destabilization by counter-NBI
![Page 3: Advances in sawtooth control for NTM prevention in JET · Sawtooth control in JET S. Coda, MHD workshop, PPPL, 22 Nov. 2004 Long sawteeth trigger (3,2) NTMs at low β N O. Sauter](https://reader036.fdocuments.net/reader036/viewer/2022070718/5ede0b2dad6a402d66694f8c/html5/thumbnails/3.jpg)
S. Coda, MHD workshop, PPPL, 22 Nov. 2004Sawtooth control in JET
Long sawteeth trigger (3,2) NTMsat low βN
O. Sauter et al., PRL 88, 105001 (2002)
Avoidance strategy:
destabilize sawteeth
keep seed island small
![Page 4: Advances in sawtooth control for NTM prevention in JET · Sawtooth control in JET S. Coda, MHD workshop, PPPL, 22 Nov. 2004 Long sawteeth trigger (3,2) NTMs at low β N O. Sauter](https://reader036.fdocuments.net/reader036/viewer/2022070718/5ede0b2dad6a402d66694f8c/html5/thumbnails/4.jpg)
S. Coda, MHD workshop, PPPL, 22 Nov. 2004Sawtooth control in JET
Fishbones are less of a concern
![Page 5: Advances in sawtooth control for NTM prevention in JET · Sawtooth control in JET S. Coda, MHD workshop, PPPL, 22 Nov. 2004 Long sawteeth trigger (3,2) NTMs at low β N O. Sauter](https://reader036.fdocuments.net/reader036/viewer/2022070718/5ede0b2dad6a402d66694f8c/html5/thumbnails/5.jpg)
S. Coda, MHD workshop, PPPL, 22 Nov. 2004Sawtooth control in JET
Discrete jump in βN at long Tst…
![Page 6: Advances in sawtooth control for NTM prevention in JET · Sawtooth control in JET S. Coda, MHD workshop, PPPL, 22 Nov. 2004 Long sawteeth trigger (3,2) NTMs at low β N O. Sauter](https://reader036.fdocuments.net/reader036/viewer/2022070718/5ede0b2dad6a402d66694f8c/html5/thumbnails/6.jpg)
S. Coda, MHD workshop, PPPL, 22 Nov. 2004Sawtooth control in JET
…but βN vs. Tst not really so simple
![Page 7: Advances in sawtooth control for NTM prevention in JET · Sawtooth control in JET S. Coda, MHD workshop, PPPL, 22 Nov. 2004 Long sawteeth trigger (3,2) NTMs at low β N O. Sauter](https://reader036.fdocuments.net/reader036/viewer/2022070718/5ede0b2dad6a402d66694f8c/html5/thumbnails/7.jpg)
S. Coda, MHD workshop, PPPL, 22 Nov. 2004Sawtooth control in JET
ICRH control of sawtooth period• +900 at center: max fast-ion stabilization• -900 at q=1: max ICCD destabilization
M.-L. Mayoral et al., PoP 11, 2607 (2004)
Both effects increase with ICRH power
![Page 8: Advances in sawtooth control for NTM prevention in JET · Sawtooth control in JET S. Coda, MHD workshop, PPPL, 22 Nov. 2004 Long sawteeth trigger (3,2) NTMs at low β N O. Sauter](https://reader036.fdocuments.net/reader036/viewer/2022070718/5ede0b2dad6a402d66694f8c/html5/thumbnails/8.jpg)
S. Coda, MHD workshop, PPPL, 22 Nov. 2004Sawtooth control in JET
ICCD destabilizationof fast-particle-stabilized sawteeth
• ITER simulation:α-particles ICRH-accelerated fast ions
• ICCD at q=1 to keep sawteeth short:tested only without strong fast particle pressure(crash criterion different)
• need 2 ICRH frequencies (H minority)• It works! Must still apply to NTM scenario (NBI)
L.-G. Eriksson et al., PRL 92, 235004 (2004)
![Page 9: Advances in sawtooth control for NTM prevention in JET · Sawtooth control in JET S. Coda, MHD workshop, PPPL, 22 Nov. 2004 Long sawteeth trigger (3,2) NTMs at low β N O. Sauter](https://reader036.fdocuments.net/reader036/viewer/2022070718/5ede0b2dad6a402d66694f8c/html5/thumbnails/9.jpg)
S. Coda, MHD workshop, PPPL, 22 Nov. 2004Sawtooth control in JET
Control experiments:fast ions vs. ICCD
![Page 10: Advances in sawtooth control for NTM prevention in JET · Sawtooth control in JET S. Coda, MHD workshop, PPPL, 22 Nov. 2004 Long sawteeth trigger (3,2) NTMs at low β N O. Sauter](https://reader036.fdocuments.net/reader036/viewer/2022070718/5ede0b2dad6a402d66694f8c/html5/thumbnails/10.jpg)
S. Coda, MHD workshop, PPPL, 22 Nov. 2004Sawtooth control in JET
Control experiments: B-field scan
![Page 11: Advances in sawtooth control for NTM prevention in JET · Sawtooth control in JET S. Coda, MHD workshop, PPPL, 22 Nov. 2004 Long sawteeth trigger (3,2) NTMs at low β N O. Sauter](https://reader036.fdocuments.net/reader036/viewer/2022070718/5ede0b2dad6a402d66694f8c/html5/thumbnails/11.jpg)
S. Coda, MHD workshop, PPPL, 22 Nov. 2004Sawtooth control in JET
Sawtooth destabilizationby counter-NBI
• Sawteeth shorter with counter- than co-NBI
![Page 12: Advances in sawtooth control for NTM prevention in JET · Sawtooth control in JET S. Coda, MHD workshop, PPPL, 22 Nov. 2004 Long sawteeth trigger (3,2) NTMs at low β N O. Sauter](https://reader036.fdocuments.net/reader036/viewer/2022070718/5ede0b2dad6a402d66694f8c/html5/thumbnails/12.jpg)
S. Coda, MHD workshop, PPPL, 22 Nov. 2004Sawtooth control in JET
Rotation scan in counter-NBI• Sawtooth period is minimum at P~4 MW
![Page 13: Advances in sawtooth control for NTM prevention in JET · Sawtooth control in JET S. Coda, MHD workshop, PPPL, 22 Nov. 2004 Long sawteeth trigger (3,2) NTMs at low β N O. Sauter](https://reader036.fdocuments.net/reader036/viewer/2022070718/5ede0b2dad6a402d66694f8c/html5/thumbnails/13.jpg)
S. Coda, MHD workshop, PPPL, 22 Nov. 2004Sawtooth control in JET
Minimum Tst found at finite rotation
Explanation?• NBCD unlikely• Fast ions unlikely• Promising candidate:
internal kink stabilization by sheared rotation
![Page 14: Advances in sawtooth control for NTM prevention in JET · Sawtooth control in JET S. Coda, MHD workshop, PPPL, 22 Nov. 2004 Long sawteeth trigger (3,2) NTMs at low β N O. Sauter](https://reader036.fdocuments.net/reader036/viewer/2022070718/5ede0b2dad6a402d66694f8c/html5/thumbnails/14.jpg)
S. Coda, MHD workshop, PPPL, 22 Nov. 2004Sawtooth control in JET
Shape also affects sawteeth
![Page 15: Advances in sawtooth control for NTM prevention in JET · Sawtooth control in JET S. Coda, MHD workshop, PPPL, 22 Nov. 2004 Long sawteeth trigger (3,2) NTMs at low β N O. Sauter](https://reader036.fdocuments.net/reader036/viewer/2022070718/5ede0b2dad6a402d66694f8c/html5/thumbnails/15.jpg)
S. Coda, MHD workshop, PPPL, 22 Nov. 2004Sawtooth control in JET
Conclusions
• NTMs are expected to be excited in ITER by long sawteeth stabilized by α-particles
• ICCD at q=1 has been proven to be an effective means of shortening sawteeth, even with large fast-ion pressure, thus preventing NTMs
• Additional sawtooth destabilization tools demonstrated on JET: rotation in counter-NBI and higher elongation
![Page 16: Advances in sawtooth control for NTM prevention in JET · Sawtooth control in JET S. Coda, MHD workshop, PPPL, 22 Nov. 2004 Long sawteeth trigger (3,2) NTMs at low β N O. Sauter](https://reader036.fdocuments.net/reader036/viewer/2022070718/5ede0b2dad6a402d66694f8c/html5/thumbnails/16.jpg)
S. Coda, MHD workshop, PPPL, 22 Nov. 2004Sawtooth control in JET
Plans for coming campaigns
• Demonstrate NTM prevention scenario with combined sawtooth stabilization/destabilization scheme– Attempt feedback on ICRH frequency for scenario optimization– Use new ICRH antenna for better coupling during ELMs
• Further characterize NTM triggering in a wider range of plasma parameters