Initiation and sustainment of tokamak plasmas with local helicity injection as the majority current drive

Perry, Justin M.; Bodner, Grant M.; Bongard, Michael W.; Burke, Marcus G.; Fonck, Raymond J.; Pachicano, Jessica L.; Pierren, Christopher; Reusch, Joshua A.; Rhodes, Alexander T.; Richner, Nathan J.; Sanchez, Cuauhtemoc Rodriguez; Schaefer, Carolyn E.; Weberski, Justin D.

doi:10.1088/1741-4326/aac72e

Title: Initiation and sustainment of tokamak plasmas with local helicity injection as the majority current drive

Journal Article · Tue Jul 03 00:00:00 EDT 2018 · Nuclear Fusion

DOI:https://doi.org/10.1088/1741-4326/aac72e· OSTI ID:1461535

^[1];

^[1]

Univ. of Wisconsin-Madison, Madison, WI (United States)

Local helicity injection (LHI) is a non-solenoidal current drive capable of achieving high-I_p tokamak startup with non-invasive current injectors in the plasma scrape-off layer. The choice of injector location within the edge region is flexible but has a profound influence on the nature of the current drive in LHI discharges. New experiments on the Pegasus ST with injection in the high-field-side, lower divertor region produce plasmas dominated by helicity injection current drive, static plasma geometry, and negligible inductive drive. Peak plasma current up to 200 kA, and a sustained plasma current of 100 kA for up to 18 ms, is demonstrated. Maximum achievable plasma current is found to scale approximately linearly with the effective loop voltage from LHI. A newly-observed MHD regime for LHI-driven plasmas in which large-amplitude n = 1 fluctuations at 20–50 kHz are abruptly reduced on the outboard side results in improved current drive. In conclusion, a simultaneous increase in high frequency fluctuations (>400 kHz) inside the plasma edge suggests short wavelength turbulence as an important current drive mechanism during LHI.

View Accepted Manuscript (DOE)

Cite

Export

Save

Research Organization:: Univ. of Wisconsin, Madison, WI (United States)

Sponsoring Organization:: USDOE Office of Science (SC), Fusion Energy Sciences (FES)

Grant/Contract Number:: FG02-96ER54375; SC0006928

OSTI ID:: 1461535

Journal Information:: Nuclear Fusion, Vol. 58, Issue 9; Related Information: J.M. Perry, G.M. Bodner, M.W. Bongard, M.G. Burke, R.J. Fonck, J.L. Pachicano, C. Pierren, J.A. Reusch, A.T. Rhodes, N.J. Richner, C. Rodriguez Sanchez, C.E. Schaefer, and J.D. Weberski, "Public Data Set: Initiation and Sustainment of Tokamak Plasmas with Local Helicity Injection as the Majority Current Drive," DOI: 10.18138/1419641; ISSN 0029-5515

Publisher:: IOP ScienceCopyright Statement

Country of Publication:: United States

Language:: English

Citation Metrics:

Cited by: 2 works

Citation information provided by
Web of Science

References (32)

Non-inductive plasma initiation and plasma current ramp-up on the TST-2 spherical tokamak Takase, Y.; Ejiri, A.; Kakuda, H. Nuclear Fusion, Vol. 53, Issue 6 https://doi.org/10.1088/0029-5515/53/6/063006	journal	May 2013
Noninductive plasma initiation and startup in the DIII-D tokamak Jackson, G. L.; Humphreys, D. A.; Hyatt, A. W. Nuclear Fusion, Vol. 51, Issue 8 https://doi.org/10.1088/0029-5515/51/8/083015	journal	July 2011
Plasma formation in START and MAST spherical tokamaks Gryaznevich, M.; Shevchenko, V.; Sykes, A. Nuclear Fusion, Vol. 46, Issue 8 https://doi.org/10.1088/0029-5515/46/8/S02	journal	July 2006
Demonstration of Plasma Startup by Coaxial Helicity Injection Raman, R.; Jarboe, T. R.; Nelson, B. A. Physical Review Letters, Vol. 90, Issue 7 https://doi.org/10.1103/PhysRevLett.90.075005	journal	February 2003
Non-inductive plasma start-up on NSTX and projections to NSTX-U using transient CHI Raman, R.; Mueller, D.; Jardin, S. C. Nuclear Fusion, Vol. 53, Issue 7 https://doi.org/10.1088/0029-5515/53/7/073017	journal	June 2013
Steady-state tokamak discharge via dc helicity injection Ono, M.; Greene, G. J.; Darrow, D. Physical Review Letters, Vol. 59, Issue 19 https://doi.org/10.1103/PhysRevLett.59.2165	journal	November 1987
Properties of dc helicity injected tokamak plasmas Darrow, D. S.; Ono, M.; Forest, C. B. Physics of Fluids B: Plasma Physics, Vol. 2, Issue 6 https://doi.org/10.1063/1.859573	journal	June 1990
Non-inductive Production of ST Plasmas with Washer Gun Sources on the Pegasus Toroidal Experiment Eidietis, N. W.; Fonck, R. J.; Garstka, G. D. Journal of Fusion Energy, Vol. 26, Issue 1-2 https://doi.org/10.1007/s10894-006-9072-z	journal	January 2007
Tokamak startup using outboard current injection on the Pegasus Toroidal Experiment Battaglia, D. J.; Bongard, M. W.; Fonck, R. J. Nuclear Fusion, Vol. 51, Issue 7 https://doi.org/10.1088/0029-5515/51/7/073029	journal	June 2011
High current plasma electron emitter Fiksel, G.; Almagri, A. F.; Craig, D. Plasma Sources Science and Technology, Vol. 5, Issue 1 https://doi.org/10.1088/0963-0252/5/1/010	journal	February 1996
Point-Source Helicity Injection Current Drive System for the Pegasus Toroidal Experiment Redd, A. J.; Battaglia, D. J.; Bongard, M. W. Journal of Fusion Energy, Vol. 28, Issue 2 https://doi.org/10.1007/s10894-008-9183-9	journal	November 2008
Impedance of an intense plasma-cathode electron source for tokamak startup Hinson, E. T.; Barr, J. L.; Bongard, M. W. Physics of Plasmas, Vol. 23, Issue 5, Article No. 052515 https://doi.org/10.1063/1.4952628	journal	May 2016
Surface effects related to voltage breakdown in CTR devices Miley, George H. Journal of Nuclear Materials, Vol. 63 https://doi.org/10.1016/0022-3115(76)90347-0	journal	December 1976
High-Voltage breakdown and conditioning of carbon and molybdenum electrodes Goebel, D. M.; Schneider, A. C. IEEE Transactions on Plasma Science, Vol. 33, Issue 4 https://doi.org/10.1109/TPS.2005.852410	journal	August 2005
Measurements of the current density in arc cathode spots from the Zeeman splitting of emission lines Vogel, N.; Juttner, B. Journal of Physics D: Applied Physics, Vol. 24, Issue 6 https://doi.org/10.1088/0022-3727/24/6/017	journal	June 1991
Surface damage by sheath effects and unipolar arcs Schwirzke, F.; Taylor, R. J. Journal of Nuclear Materials, Vol. 93-94 https://doi.org/10.1016/0022-3115(80)90207-X	journal	October 1980
Simulated flux-rope evolution during non-inductive startup in Pegasus O'Bryan, J. B.; Sovinec, C. R. Plasma Physics and Controlled Fusion, Vol. 56, Issue 6 https://doi.org/10.1088/0741-3335/56/6/064005	journal	February 2014
Simulation of current-filament dynamics and relaxation in the Pegasus Spherical Tokamak O’Bryan, J. B.; Sovinec, C. R.; Bird, T. M. Physics of Plasmas, Vol. 19, Issue 8 https://doi.org/10.1063/1.4746089	journal	August 2012
The Formation of a Tokamak-like Plasma in Initial Experiments Using an Outboard Plasma Gun Current Source Battaglia, D. J.; Bongard, M. W.; Fonck, R. J. Journal of Fusion Energy, Vol. 28, Issue 2 https://doi.org/10.1007/s10894-008-9165-y	journal	December 2008
H-mode plasmas at very low aspect ratio on the Pegasus Toroidal Experiment Thome, K. E.; Bongard, M. W.; Barr, J. L. Nuclear Fusion, Vol. 57, Issue 2, Article No. 022018 https://doi.org/10.1088/0029-5515/57/2/022018	journal	September 2016
Attainment of High Normalized Current by Current Profile Manipulation in the Pegasus Toroidal Experiment Garstka, G. D.; Unterberg, E. A.; Battaglia, D. J. Journal of Fusion Energy, Vol. 27, Issue 1-2 https://doi.org/10.1007/s10894-007-9094-1	journal	July 2007
Noninductively Driven Tokamak Plasmas at Near-Unity Toroidal Beta Schlossberg, D. J.; Bodner, G. M.; Bongard, M. W. Physical Review Letters, Vol. 119, Issue 3, Article No. 035001 https://doi.org/10.1103/PhysRevLett.119.035001	journal	July 2017
A novel, cost-effective, multi-point Thomson scattering system on the Pegasus Toroidal Experiment (invited) Schlossberg, D. J.; Bodner, G. M.; Bongard, M. W. Review of Scientific Instruments, Vol. 87, Issue 11, Article No. 11E403 https://doi.org/10.1063/1.4962193	journal	September 2016
Non-inductively driven tokamak plasmas at near-unity βt in the P egasus toroidal experiment Reusch, J. A.; Bodner, G. M.; Bongard, M. W. Physics of Plasmas, Vol. 25, Issue 5 https://doi.org/10.1063/1.5017966	journal	May 2018
ITER L mode confinement database Kaye, S. M.; Greenwald, M.; Stroth, U. Nuclear Fusion, Vol. 37, Issue 9 https://doi.org/10.1088/0029-5515/37/9/I10	journal	September 1997
Experimental scaling of fluctuations and confinement with Lundquist number in the reversed-field pinch Stoneking, M. R.; Chapman, J. T.; Den Hartog, D. J. Physics of Plasmas, Vol. 5, Issue 4 https://doi.org/10.1063/1.872670	journal	April 1998
Continuous, edge localized ion heating during non-solenoidal plasma startup and sustainment in a low aspect ratio tokamak Burke, M. G.; Barr, J. L.; Bongard, M. W. Nuclear Fusion, Vol. 57, Issue 7, Article No. 076010 https://doi.org/10.1088/1741-4326/aa6f2b	journal	May 2017
Flux amplification in Helicity Injected Torus (HIT–II) coaxial helicity injection discharges Redd, A. J.; Jarboe, T. R.; Hamp, W. T. Physics of Plasmas, Vol. 15, Issue 2, Article No. 022506 https://doi.org/10.1063/1.2841030	journal	February 2008
The instability of a pinched fluid with a longitudinal magnetic field Kruskal, M.; Tuck, J. L. Proceedings of the Royal Society of London. Series A. Mathematical and Physical Sciences, Vol. 245, Issue 1241, p. 222-237 https://doi.org/10.1098/rspa.1958.0079	journal	June 1958
Current-Driven Rotating-Kink Mode in a Plasma Column with a Non-Line-Tied Free End Furno, I.; Intrator, T. P.; Ryutov, D. D. Physical Review Letters, Vol. 97, Issue 1 https://doi.org/10.1103/PhysRevLett.97.015002	journal	July 2006
Stabilizing impact of high gradient of β on microturbulence Bourdelle, C.; Dorland, W.; Garbet, X. Physics of Plasmas, Vol. 10, Issue 7 https://doi.org/10.1063/1.1585032	journal	July 2003
Public Data Set: Advancing Local Helicity Injection for Non-Solenoidal Tokamak Startup Bongard, Michael; Bodner, Grant; Burke, Marcus University of Wisconsin-Madison https://doi.org/10.18138/1489772	dataset	January 2019

Cited By (3)

Public Data Set: Initiation and Sustainment of Tokamak Plasmas with Local Helicity Injection as the Majority Current Drive Perry, Justin; Bodner, Grant; Bongard, Michael Pegasus-Supplementary information for journal article at DOI: https://doi.org/10.1088/1741-4326/aac72e, 1 file (17.1 MB) https://doi.org/10.18138/1419641	dataset	July 2018
Public Data Set: Spatial Heterodyne Spectroscopy for High Speed Measurements of Stark Split Neutral Beam Emission in a High Temperature Plasma Burke, Marcus; Fonck, Raymond; McKee, George University of Wisconsin-Madison https://doi.org/10.18138/1435641	dataset	January 2018
Public Data Set: Advancing Local Helicity Injection for Non-Solenoidal Tokamak Startup Bongard, Michael; Bodner, Grant; Burke, Marcus University of Wisconsin-Madison https://doi.org/10.18138/1489772	dataset	January 2019

Similar Records

Characteristics of Ultralow Aspect Ratio Toroidal Plasmas and Non-Solenoidal Startup and Edge Stability Studies at Near-Unity Aspect Ratio (Final Report)

Technical Report · Mon Mar 15 00:00:00 EDT 2021 · OSTI ID:1461535

Fonck, Raymond J.; Bongard, Michael W.

Test of Point-Source Helicity Injection for Non-Solenoidal Startup in NSTX

Technical Report · Fri Dec 21 00:00:00 EST 2018 · OSTI ID:1461535

Fonck, Raymond John; Reusch, Joshua Adam

Continuous, edge localized ion heating during non-solenoidal plasma startup and sustainment in a low aspect ratio tokamak

Journal Article · Tue May 16 00:00:00 EDT 2017 · Nuclear Fusion · OSTI ID:1461535

Burke, Marcus G.; Barr, Jayson L.; Bongard, Michael W.; +5 more

Related Subjects

70 PLASMA PHYSICS AND FUSION TECHNOLOGY
tokamak
non-inductive current drive
magnetic helicity
helicity injection
spherical tokamak

Title: Initiation and sustainment of tokamak plasmas with local helicity injection as the majority current drive

Citation Formats

References (32)

Cited By (3)

Similar Records

Related Subjects