Stability of a reversed field pinch with resistive and distant boundaries

Ho, Y. L.; Prager, S. C.

doi:10.1063/1.866705

Cited by 42 publications

(27 citation statements)

References 19 publications

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“…Resistive shell. Recently, interest has developed in operating pinches with thin or resistive shells whose time constant is much shorter than the discharge duration, and the linear [32][33][34] and non-linear [35][36][37][38] stability of such systems have been studied. Operation with a thin shell is of interest because it allows time varying plasma position control by B v and eliminates field errors due to gaps and ports in a thick shell; it is important in a reactor.…”

Section: Stability: Influence Of a Resistive Shellmentioning

confidence: 99%

The reversed field pinch

Bodin

1990

Nucl. Fusion

145

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The paper summarizes the theoretical basis for the RFP and reviews the status of research in this field. The RFP is a relaxed state system well described by Taylor's theory which explains many observations. The RFP is of interest because its study will increase the understanding of toroidal confinement in general, which might lead to better reactor designs, and the RFP itself has potential as a reactor, for example the improved, high energy density, compact RFP reactor. In the last five or ten years, RFP research has expanded, with some 15-20 machines operating or under construction, and the plasma parameters have improved substantially, with a confinement time of 0.5-1 ms and temperatures approaching 1 keV; values of (3 e -5-15% are reached routinely. Following an overview of recent results, three key problems are discussed in more detail: (1) resistivity, edge physics and ion heating (the ions are heated by fluctuations which drive the RFP dynamo); (2) operation of the RFP with an (electrically) thin shell which permits the growth of new unstable modes which degrade the confinement; and (3) scaling. Over the current range of 0.5 MA, favourable scaling trends of temperature and confinement with current are identified, but experiments at much higher currents on the two mega-ampere machines -RFX at Padua and CPRF at Los Alamosdue to operate in the early 1990s, are needed. A brief account of the compact RFP reactor is given, followed by a summary with an indication of future trends.

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Section: Stability: Influence Of a Resistive Shellmentioning

confidence: 99%

The reversed field pinch

Bodin

1990

Nucl. Fusion

145

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“…[9][10][11] The stabilizing effect of the ideal conducting shell on the MHD modes is lost, leading to the destabilization of resistive shell modes ͑with internally on-axis resonant modes and externally nonresonant kink modes being the main concern͒. [9][10][11] The stabilizing effect of the ideal conducting shell on the MHD modes is lost, leading to the destabilization of resistive shell modes ͑with internally on-axis resonant modes and externally nonresonant kink modes being the main concern͒.…”

Section: Introductionmentioning

confidence: 99%

Locked modes in two reversed-field pinch devices of different size and shell system

Malmberg

Brunsell

Yagi³

et al. 2000

Physics of Plasmas

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The behavior of locked modes in two reversed-field pinch devices, the Toroidal Pinch Experiment ͑TPE-RX͒ ͓Y. is analyzed and compared. The main characteristics of the locked mode are qualitatively similar. The toroidal distribution of the mode locking shows that field errors play a role in both devices. The probability of phase locking is found to increase with increasing magnetic fluctuation levels in both machines. Furthermore, the probability of phase locking increases with plasma current in TPE-RX despite the fact that the magnetic fluctuation levels decrease. A comparison with computations using a theoretical model estimating the critical mode amplitude for locking ͓R. Fitzpatrick et al., Phys. Plasmas 6, 3878 ͑1999͔͒ shows a good correlation with experimental results in TPE-RX. In Extrap T2, the magnetic fluctuations scale weakly with both plasma current and electron densities. This is also reflected in the weak scaling of the magnetic fluctuation levels with the Lundquist number (ϳS Ϫ0.06 ). In TPE-RX, the corresponding scaling is ϳS Ϫ0.18 .

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“…In addition to providing an illustrative example of multiple-interface equilibria, cylindrical equilibria provide a simple template upon which to explore complicated stability limits. A similar approach was taken by Ho and Prager [8], in their exploration of current driven stability limits in partially relaxed reverse field pinch configurations. To compute solutions in cylindrical geometry, we use the co-ordinate system (r, θ, z), with equilibrium variations permitted only in the radial direction.…”

Section: Cylindrical Equilibriamentioning

confidence: 98%

Stepped pressure profile equilibria in cylindrical plasmas via partial Taylor relaxation

2006

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One of the most important advances in magnetically confined fusion plasma physics has been the discovery of high confinement regimes, where at sufficiently high heating power, the plasma self-organizes to produce internal transport barriers (ITB's). A possible explanation for the existence of such barriers is that they represent constrained minimum energy states, where the plasma within the barrier satisfies ideal MHD, and the plasma between barriers is in a Taylor relaxed state. In this work we develop a multiple interface variational formulation, comprising multiple Taylor-relaxed plasma regions, each of which are separated by an ideal MHD barrier. Application to a plasma cylinder is a generalization of the analysis of the treatment of Kaiser and Uecker, Q. Jl. Mech. Appl. Math.,57(1), 2004, who treated the single interface in cylindrical geometry. Expressions for the equilibrium field are generated, and equilibrium states computed. Unlike other Taylor relaxed equilibria, for the equilibria investigated here, only the plasma core necessarily has reverse magnetic shear. We show the existence of tokamak like equilibria, with increasing safety factor and stepped-pressure profiles.

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Stability of a reversed field pinch with resistive and distant boundaries

Cited by 42 publications

References 19 publications

The reversed field pinch

The reversed field pinch

Locked modes in two reversed-field pinch devices of different size and shell system

Stepped pressure profile equilibria in cylindrical plasmas via partial Taylor relaxation

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