TITLE

Stable spheromak formation by merging in an oblate flux conserver

AUTHOR(S)
Gray, T.; Brown, M. R.; Cothran, C. D.; Marklin, G.; Schaffer, M. J.
PUB. DATE
March 2010
SOURCE
Physics of Plasmas;Mar2010, Vol. 17 Issue 3, p032510
SOURCE TYPE
Academic Journal
DOC. TYPE
Article
ABSTRACT
An axisymmetric spheromak formed by the dynamic merging of two smaller spheromaks of the same magnetic helicity in the Swarthmore Spheromak Experiment (SSX) [M. R. Brown, Phys. Plasmas 6, 1717 (1999)] has been observed and characterized. The spheromak is formed in an oblate (tilt stable), trapezoidal, 6 mm wall copper flux conserver in SSX, which is 0.5 m in diameter and L=0.4 m in length at its largest dimensions. This configuration is formed by cohelicity merging of two spheromaks (either both right-handed or both left-handed) in which the merging poloidal fluxes are parallel (i.e., no field reversal for reconnection to occur initially). After a period of dynamic and nonaxisymmetric activity, the configuration ultimately relaxes to an axisymmetric state. A nonaxisymmetric tilted state, very close in total energy to the axisymmetric state, is also sometimes observed. This configuration is characterized by a suite of magnetic probe arrays for magnetic structure B(r,t), ion Doppler spectroscopy for Ti and flow, and interferometry for ne. The magnetic structures of both states match well to computed eigenstates.
ACCESSION #
48912102

 

Related Articles

  • Reactor prospect of spheromak concept by electrostatic helicity injection. Tang, X. Z.; Boozer, A. H. // Physics of Plasmas;Jul2008, Vol. 15 Issue 7, p072510 

    The highest performing spheromaks in the laboratory are formed by electrostatic helicity injection. Discharges with up to 1 MA plasma current and core electron temperature as high as 500 eV have been recently obtained. For such a scheme to scale-up to a reactor, however, a much higher current...

  • Scale-up of spherical tokamak solenoid-free startup by coaxial helicity injection. Tang, X. Z.; Boozer, A. H. // Physics of Plasmas;Oct2007, Vol. 14 Issue 10, p100704 

    Current multiplication and flux amplification are two critical measures in assessing the usefulness of magnetic helicity injection for forming the plasma confining magnetic field in laboratory spheromak and spherical tokamak (ST) experiments. While the two concepts are closely related for...

  • Sustained spheromak coaxial gun operation in the presence of an n=1 magnetic distortion. Holcomb, C. T.; Jarboe, T. R.; Hill, D. N.; Woodruff, S.; Wood, R. D. // Physics of Plasmas;Feb2006, Vol. 13 Issue 2, p022504 

    The Sustained Spheromak Physics Experiment (SSPX) [E. B. Hooper, L. D. Pearlstein, and R. H. Bulmer, Nucl. Fusion 39, 863 (1999)] uses a magnetized coaxial gun to form and sustain spheromaks by helicity injection. Internal probes give the magnetic profile within the gun. An analysis of these...

  • Experimental determination of the conservation of magnetic helicity from the balance between source and spheromak. Barnes, Cris W.; Fernández, J. C.; Henins, I.; Hoida, H. W.; Jarboe, T. R.; Knox, S. O.; Marklin, G. J.; McKenna, K. F. // Physics of Fluids (00319171);Oct86, Vol. 29 Issue 10, p3415 

    The conjecture that magnetic helicity (linked flux) is conserved in magnetized plasmas for time scales that are short compared to the resistive diffusion time is experimentally tested in the CTX spheromak [Phys. Rev. Lett. 45, 1264 ( 1980); 51, 39 ( 1983); Nucl. Fusion 24, 267 (1984) ]. Helicity...

  • Fractional Josephson vortices: oscillating macroscopic spins. Gaber, T.; Buckenmaier, K.; Koelle, D.; Kleiner, R.; Goldobin, E. // Applied Physics A: Materials Science & Processing;Nov2007, Vol. 89 Issue 3, p587 

    Fractional Josephson vortices carry a magnetic flux Φ, which is a fraction of the magnetic flux quantum Φ0≈2.07×10-15 Wb. We consider a fractional vortex which spontaneously appears at a phase discontinuity. Its properties are very different from the properties of the usual...

  • Magnetic reconnection during flux conversion in a driven spheromak. Hooper, E. B.; Kopriva, T. A.; Cohen, B. I.; Hill, D. N.; McLean, H. S.; Wood, R. D.; Woodruff, S.; Sovinec, C. R. // Physics of Plasmas;Sep2005, Vol. 12 Issue 9, p092503 

    During buildup of a spheromak by helicity injection, magnetic reconnection converts toroidal flux into poloidal flux. This physics is explored in the resistive magnetohydrodynamic code, NIMROD [C. R. Sovinec, A. H. Glasser, T. A. Gianakon, D. C. Barnes, R. A. Nebel, S. E. Kruger, D. D. Schnack,...

  • Aspect-ratio effects in the driven, flux-core spheromak. Hooper, E. B.; Romero-Talamás, C. A.; LoDestro, L. L.; Wood, R. D.; McLean, H. S. // Physics of Plasmas;May2009, Vol. 16 Issue 5, p052506 

    Resistive magnetohydrodynamic simulations are used to evaluate the effects of the aspect ratio A (length to radius ratio) in a spheromak driven by coaxial helicity injection. The simulations are benchmarked against the Sustained Spheromak Physics Experiment (SSPX) [R. D. Wood et al., Nucl....

  • Numerical studies of a steady state axisymmetric co-axial helicity injection plasma. Tang, X.Z.; Boozer, A.H. // Physics of Plasmas;Jan2004, Vol. 11 Issue 1, p171 

    Steady state current profile, plasma potential, and plasma flow of an electrostatically driven co-axial helicity injection (CHI) plasma with axisymmetry are numerically investigated using both an open field line Grad–Shafranov equilibrium model and self-consistent initial value...

  • The Magnetic Field, Horizontal Motion and Helicity in a Fast Emerging Flux Region which Eventually forms a Delta Spot. Jihong Liu; Hongqi Zhang // Solar Physics;Mar2006, Vol. 234 Issue 1, p21 

    We studied the behavior of magnetic field, horizontal motion and helicity in a fast emerging flux region NOAA 10488 which eventually forms a δ spot. It is found that the rotation of photospheric footpoints forms in the earlier stage of magnetic flux emergence and the relative shear motion of...

Share

Read the Article

Courtesy of VIRGINIA BEACH PUBLIC LIBRARY AND SYSTEM

Sorry, but this item is not currently available from your library.

Try another library?
Sign out of this library

Other Topics