Large-volume flux closure during plasmoid-mediated reconnection in coaxial helicity injection

Ebrahimi, F.; Raman, R.

doi:10.1088/0029-5515/56/4/044002

Large-volume flux closure during plasmoid-mediated reconnection in coaxial helicity injection

Journal Article · Wed Mar 23 00:00:00 EDT 2016 · Nuclear Fusion

DOI:https://doi.org/10.1088/0029-5515/56/4/044002· OSTI ID:1258451

^[1]; Raman, R. ^[2]

Princeton Plasma Physics Lab. (PPPL), Princeton, NJ (United States); Princeton Univ., Princeton, NJ (United States)
Univ. of Washington, Seattle, WA (United States)

A large-volume flux closure during transient coaxial helicity injection (CHI) in NSTX-U is demonstrated through resistive magnetohydrodynamics (MHD) simulations. Several major improvements, including the improved positioning of the divertor poloidal field coils, are projected to improve the CHI start-up phase in NSTX-U. Simulations in the NSTX-U configuration with constant in time coil currents show that with strong flux shaping the injected open field lines (injector flux) rapidly reconnect and form large volume of closed flux surfaces. This is achieved by driving parallel current in the injector flux coil and oppositely directed currents in the flux shaping coils to form a narrow injector flux footprint and push the injector flux into the vessel. As the helicity and plasma are injected into the device, the oppositely directed field lines in the injector region are forced to reconnect through a local Sweet-Parker type reconnection, or to spontaneously reconnect when the elongated current sheet becomes MHD unstable to form plasmoids. In these simulations for the first time, it is found that the closed flux is over 70% of the initial injector flux used to initiate the discharge. Furthermore, these results could work well for the application of transient CHI in devices that employ super conducting coils to generate and sustain the plasma equilibrium.

View Accepted Manuscript (DOE)

Research Organization:: Princeton Plasma Physics Laboratory (PPPL), Princeton, NJ (United States)

Sponsoring Organization:: USDOE Office of Science (SC), Fusion Energy Sciences (FES); USDOE Office of Science (SC), Fusion Energy Sciences (FES) (SC-24)

Grant/Contract Number:: AC02-09CH11466; FG02-99ER54519; SC0010565

OSTI ID:: 1258451

Alternate ID(s):: OSTI ID: 1243000

Journal Information:: Nuclear Fusion, Journal Name: Nuclear Fusion Journal Issue: 4 Vol. 56; ISSN 0029-5515

Publisher:: IOP ScienceCopyright Statement

Country of Publication:: United States

Language:: English

References (17)

Large-volume flux closure during plasmoid-mediated reconnection in coaxial helicity injection Ebrahimi, F.; Raman, R. Nuclear Fusion, Vol. 56, Issue 4, 34.65 MB https://doi.org/10.11578/1354837	dataset	April 2016
Large-volume flux closure during plasmoid-mediated reconnection in coaxial helicity injection Ebrahimi, F.; Raman, R. Nuclear Fusion, Vol. 56, Issue 4, 34.65 MB https://doi.org/10.11578/1366481	dataset	April 2016
Large-volume flux closure during plasmoid-mediated reconnection in coaxial helicity injection Ebrahimi, F.; Raman, R. Princeton Plasma Physics Laboratory (PPPL), Princeton, NJ (United States) https://doi.org/10.11578/1562059	dataset	January 2016
The three-dimensional magnetohydrodynamics of ac helicity injection in the reversed field pinch Ebrahimi, F.; Prager, S. C.; Sarff, J. S. Physics of Plasmas, Vol. 10, Issue 4 https://doi.org/10.1063/1.1555622	journal	April 2003
The internal magnetic field structures and current density profiles in the Helicity Injected Spherical Torus plasma driven by coaxial helicity injection Nagata, Masayoshi; Kanki, Takashi; Fukumoto, Naoyuki Physics of Plasmas, Vol. 10, Issue 7 https://doi.org/10.1063/1.1580815	journal	July 2003
Instability of current sheets and formation of plasmoid chains Loureiro, N. F.; Schekochihin, A. A.; Cowley, S. C. Physics of Plasmas, Vol. 14, Issue 10 https://doi.org/10.1063/1.2783986	journal	October 2007
Equilibrium evolution in oscillating-field current-drive experiments McCollam, K. J.; Anderson, J. K.; Blair, A. P. Physics of Plasmas, Vol. 17, Issue 8 https://doi.org/10.1063/1.3461167	journal	August 2010
Magnetic reconnection process in transient coaxial helicity injection Ebrahimi, F.; Hooper, E. B.; Sovinec, C. R. Physics of Plasmas, Vol. 20, Issue 9 https://doi.org/10.1063/1.4821974	journal	September 2013
Physics of forced magnetic reconnection in coaxial helicity injection experiments in National Spherical Torus Experiment Ebrahimi, F.; Raman, R.; Hooper, E. B. Physics of Plasmas, Vol. 21, Issue 5 https://doi.org/10.1063/1.4875337	journal	May 2014
The impedance and energy efficiency of a coaxial magnetized plasma source used for spheromak formation and sustainment Barnes, Cris W.; Jarboe, T. R.; Marklin, G. J. Physics of Fluids B: Plasma Physics, Vol. 2, Issue 8 https://doi.org/10.1063/1.859459	journal	August 1990
Magnetic reconnection via current sheets Biskamp, D. Physics of Fluids, Vol. 29, Issue 5 https://doi.org/10.1063/1.865670	journal	January 1986
Plasmoids Formation During Simulations of Coaxial Helicity Injection in the National Spherical Torus Experiment Ebrahimi, F.; Raman, R. Physical Review Letters, Vol. 114, Issue 20 https://doi.org/10.1103/PhysRevLett.114.205003	journal	May 2015
Slow Formation and Sustainment of Spheromaks by a Coaxial Magnetized Plasma Source Jarboe, T. R.; Henins, I.; Sherwood, A. R. Physical Review Letters, Vol. 51, Issue 1 https://doi.org/10.1103/PhysRevLett.51.39	journal	July 1983
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
Efficient Generation of Closed Magnetic Flux Surfaces in a Large Spherical Tokamak Using Coaxial Helicity Injection Raman, R.; Nelson, B. A.; Bell, M. G. Physical Review Letters, Vol. 97, Issue 17 https://doi.org/10.1103/PhysRevLett.97.175002	journal	October 2006
Plasmoid-induced-reconnection and fractal reconnection Shibata, Kazunari; Tanuma, Syuniti Earth, Planets and Space, Vol. 53, Issue 6 https://doi.org/10.1186/BF03353258	journal	June 2001
Formation and Steady-State Sustainment of a Tokamak by Coaxial Helicity Injection Jarboe, Thomas R. Fusion Technology, Vol. 15, Issue 1 https://doi.org/10.13182/FST89-1	journal	January 1989

Cited By (8)

Large-volume flux closure during plasmoid-mediated reconnection in coaxial helicity injection Ebrahimi, F.; Raman, R. Nuclear Fusion, Vol. 56, Issue 4, 34.65 MB https://doi.org/10.11578/1354837	dataset	April 2016
Nonlinear reconnecting edge localized modes in current-carrying plasmas Ebrahimi, F. Physics of Plasmas, Vol. 24, Issue 5 https://doi.org/10.1063/1.4983631	journal	May 2017
Numerical study and optimization of the formation and sustainment of a coaxial helicity injection spheromak O'Bryan, J. B.; Romero-Talamás, C. A.; Woodruff, S. Physics of Plasmas, Vol. 25, Issue 11 https://doi.org/10.1063/1.5043299	journal	November 2018
Application of transient CHI plasma startup to future ST and AT devices Hammond, K. C.; Raman, R.; Jardin, S. C. Physics of Plasmas, Vol. 26, Issue 3 https://doi.org/10.1063/1.5087259	journal	March 2019
Three-dimensional plasmoid-mediated reconnection and the effect of toroidal guide field in simulations of coaxial helicity injection Ebrahimi, F. Physics of Plasmas, Vol. 26, Issue 9 https://doi.org/10.1063/1.5098482	journal	September 2019
Initial results from solenoid-free plasma start-up using Transient CHI on QUEST Kuroda, K.; Raman, R.; Hanada, K. Plasma Physics and Controlled Fusion, Vol. 60, Issue 11 https://doi.org/10.1088/1361-6587/aadcb7	journal	September 2018
Application of Townsend avalanche theory to tokamak startup by coaxial helicity injection Hammond, K. C.; Raman, R.; Volpe, F. A. Nuclear Fusion, Vol. 58, Issue 1 https://doi.org/10.1088/1741-4326/aa8fa4	journal	November 2017
Large-volume flux closure during plasmoid-mediated reconnection in coaxial helicity injection Ebrahimi, F.; Raman, R. Princeton Plasma Physics Laboratory (PPPL), Princeton, NJ (United States) https://doi.org/10.11578/1562059	dataset	January 2016

Figures / Tables (6)

Similar Records

Large-volume flux closure during plasmoid-mediated reconnection in coaxial helicity injection

Dataset · Thu Dec 31 23:00:00 EST 2015 · OSTI ID:1354837

Magnetic reconnection process in transient coaxial helicity injection

Journal Article · Sun Sep 15 00:00:00 EDT 2013 · Physics of Plasmas · OSTI ID:22220568

Physics of forced magnetic reconnection in coaxial helicity injection experiments in National Spherical Torus Experiment

Journal Article · Thu May 15 00:00:00 EDT 2014 · Physics of Plasmas · OSTI ID:22252935

Related Subjects

70 PLASMA PHYSICS AND FUSION TECHNOLOGY

Large-volume flux closure during plasmoid-mediated reconnection in coaxial helicity injection

Citation Formats

References (17)

Cited By (8)

Figures / Tables (6)

Similar Records

Related Subjects