Stability and Diffusion of the Zt-1 Reversed-Field Pinch

Haberstich, A.; Baker, D. A.; Marco, John; Mann, L.W.; Ortolani, S.

doi:10.1016/b978-0-08-020941-8.50039-1

Cited by 4 publications

(8 citation statements)

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“…By this means it is possible to test rigorously for the ideal-MHD stability of an arbitrary cylindrical pinch configuration for all values of m and k. In the RFP, since B# ~ B^ and q < 1, toroidal effects can be neglected and cylindrical theory is sufficiently accurate. Toroidal calculations have been carried out at Los Alamos [98,99] and no significant difference has been found.…”

Section: Generalmentioning

confidence: 99%

Reversed-field-pinch research

1980

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Theoretical and experimental research in the reversed-field pinch (RFP) is reviewed. In this system, Bθ ∼ Bϕ, q < 1 and Bϕ reverses in the outer regions of the plasma; stability at relatively high values of β is possible because there is high shear and, experimentally, confinement with β > 10% has been observed. Following a historical review of pinch research, the basic theoretical properties of the RFP are established including the equilibrium, toroidal displacement, diffusion and confinement; studies of ideal and dissipative MHD stability theory are then described. Experimental and theoretical work on relaxation and self-reversal, the process whereby an RFP distribution can be set up spontaneously and subsequently sustained, is presented and discussed. There follows a general account of RFP experiments. These are divided into ‘fast experiments’, which utilize small-bore insulating tori in which the distribution is usually set up by fast programming on microsecond timescales, and ‘slow experiments’, carried out in large metal-walled tori in which the field configuration is set up slowly by self-reversal on millisecond timescales. A brief account of RFP reactor studies and of new and future experiments is then given, followed finally by a general discussion in which the main conclusions are presented.

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Section: Generalmentioning

confidence: 99%

Reversed-field-pinch research

1980

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“…The calculation of MFD stable equilibria has been extended to toroidal coordinates (32)(33)(34) in 1972 using numerical techniques, vhere the stability of localized modes is determined by the Mercier (32) criterion (toroidal analog of the Suydam criterion) published in 1960.…”

Section: A Theorymentioning

confidence: 99%

“…II.B) has also been performed. A time-dependent, one-dimension MH5 code (34) with anisotropic electrical resistivity, heat conduction, and impurity radiation has been used to investigate the post implosion phase of ZT-I. The electrical resistivity appears to be nearly classical on axis and must increase by two orders of magnitude from the axis to the discharge tube wall in order to approximate the experimental results.…”

Section: A Theorymentioning

confidence: 99%

Toroidal fusion reactor design based on the reversed-field pinch

Hagenson

1978

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“…Recent results in experimental RFP research are given in Refs [5] and include measurements on ZT1 (minor radius a = 0.10 m) and ZTS (a = 0.15 m) at Los Alamos, TPE (a = 0.058 m) at Tanashi, Eta-Beta (a = 0.0485 m) at Padua and HBTX1 (a = 0.06 m) at Culham. Previous work on these devices is described in Refs [6]. However, these results refer mainly to fast pinch discharges in devices of relatively small radius, which appear to operate in a regime different to that of large slow RFP devices such as ZETA (a = 0.5 m) because of a considerable difference in the ratio of the Alfven or MHD instability growth time T\ to the current rise time TR and the configuration time T C in the two types of apparatus.…”

Section: Introductionmentioning

confidence: 99%

“…Subsequent theoretical predictions by Taylor [17] and Kadomtsev [18] suggest that a force-free RFP configuration develops spontaneously during the unstable setting-up phase A as the plasma tries to relax towards a minimum energy state, and although the details of the formation of the RFP in this way are not yet understood these theories do help to explain why it should occur. Self-reversal is observed in the fast RFP devices referred to above [5], which also offer an alternative method for generating RFP discharges by fast programming of the currents [5,6,8].…”

Section: Introductionmentioning

confidence: 99%

Evolution of the reversed-field pinch

Christiansen

Roberts

1978

Nucl. Fusion

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This paper discusses the time evolution of a slow Reversed-Field Pinch during the sustainment phase, starting from an initial low-β configuration at the end of the setting-up phase which corresponds approximately to a Taylor Reversed-Field Bessel-function state. Calculations are made with a one-dimensional MHD (1DMHD) equilibrium and diffusion code. Because of local overheating and consequent rise of plasma pressure the central region of low shear becomes Suydam-unstable, and it is assumed that this results in local MHD turbulence, so flattening out the central density and temperature profiles and leading to a quasi-steady state which gradually evolves in time. The pinch then consists of two main zones, a central Suydam-unstable core I and an outer MHD-stable layer II which is responsible for confinement. An external zone III may exist near the wall but is not studied here. The configuration time τc depends on the time for which the trapped positive Bz flux ψ+ can persist against resistive diffusion. This in turn depends on the electron temperature in zone II and hence on the anomalous electron thermal conductivity that is assumed in the model. Some information can be obtained by normalizing the phenomenological transport coefficients used in the code to the measurements made on ZETA but this does not provide a very sensitive check. Further information can be obtained from empirical tokamak scaling laws. Then the performance of the proposed device RFX is predicted. A significant difference between ZETA and RFX is that in ZETA it was the disappearance of the negative flux ψ− that terminated the quiescent period, while in RFX it is the positive flux ψ+ that controls the configuration time. This leads to a substantial improvement in predicted performance.

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Stability and Diffusion of the Zt-1 Reversed-Field Pinch

Cited by 4 publications

References 1 publication

Reversed-field-pinch research

Reversed-field-pinch research

Toroidal fusion reactor design based on the reversed-field pinch

Evolution of the reversed-field pinch

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