The relationship between the 'tangled discharge' and 'dynamo' models of the magnetic relaxation process

It is shown that these two models are closely related. The 'Tangled Discharge Model' (TDM) necessarily involves a non-vanishing , the so-called 'dynamo' effect, while the effective functioning of this term in the 'Dynamo' models is shown to require a stochastic magnetic field structure. There is no inconsistency between this conclusion and the fact that the fully-relaxed state may be described by analytical forms such as the 'Bessel Function Model' which apparently contain good flux surfaces. The TDM is not a satisfactory description of the behaviour of present relaxed-state systems, but might be appropriate in the limit of large Lundquist number S.

[1]  K. Kusano,et al.  Simulation study of the self-reversal process in the reversed-field pinch based on a non-linearly driven reconnection model , 1986 .

[2]  G. Doolen,et al.  Driven, steady-state RFP computations , 1988, Journal of Plasma Physics.

[3]  L. Turner.  Analytic solutions of ∇ × B=λB having separatrices for geometries with one ignorable coordinate , 1984 .

[4]  G. Miller.  Resistive evolution of plasmas with imperfect magnetic surfaces , 1988 .

[5]  H. K. Moffatt.  Magnetic Field Generation in Electrically Conducting Fluids , 1978 .

[6]  P. Kirby.  Numerical Simulation of The Reversed Field Pinch , 1988 .

[7]  E. J. Caramana,et al.  The dynamo effect in sustained reversed-field pinch discharges , 1984 .

[8]  M. G. Rusbridge.  Conditions for the attainment of the minimum-energy state of a diffuse pinch discharge , 1982 .

[9]  M. G. Rusbridge.  A model of field reversal in the diffuse pinch , 1977 .

[10]  H. Tsui,et al.  Behaviour of discharges with deep reversal in HBTX1B , 1988 .

[11]  A. A. Mirin,et al.  Compressibility as a feature of field reversal maintenance in the reversed‐field pinch , 1985 .

[12]  A. Jacobson,et al.  Nonlocal dc electrical conductivity of a Lorentz plasma in a stochastic magnetic field , 1984 .

[13]  Wright,et al.  Observations of spheromak equilibria which differ from the minimum-energy state and have internal kink distortions. , 1986, Physical review letters.

[14]  J B Taylor,et al.  Relaxation and magnetic reconnection in plasmas , 1986 .

[15]  D. Meyerhofer,et al.  Verification of the Taylor (minimum energy) state in a spheromak , 1986 .

[16]  T. G. Cowling,et al.  The Magnetic Field of Sunspots , 1933 .

[17]  P. Browning,et al.  Partially relaxed magnetic field equilibria in a gun-injected spheromak , 1990 .