Effect of high-frequency electromagnetic field on the stability of a slightly nonhomogeneous magnetized plasma

Demirkhanov, R.A.; Gutkin, T.I.; Lozovsky, S.N.; Nekrasov, F.M.; Sidorov, V.

doi:10.1016/0031-8914(70)90134-5

Cited by 4 publications

(6 citation statements)

References 2 publications

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“…The above theoretical considerations agree with the results of experimental investigations [6][7][8]. The displacement of the pinch, measured from the asymmetry of distribution of the high-frequency field in the cross-section of the chamber, is described sufficiently well by formulae ( 19)and (19a).…”

Section: Discussion Of the Resultssupporting

confidence: 85%

“…We also assume fulfilment of the conditions of quasi-stationarity (> (| , r c « c/f, and when \ = oo only r c « c/f), so that it is possible, when formulating the equilibrium conditions, to disregard the electrical components of the high-frequency field. Finally, the set of conditions under which subsequent results will be valid are: which approximately occur under experimental conditions [6][7][8]. For the special case where there is no longitudinal static field and the exciting high-frequency currents are purely meridional (J os = 0, J^ f 0), the problem of the equilibrium of a toroidal pinch has been solved by Volkov [3] and also by Breus and Kurdyumov [4].…”

Section: Statement Of the Problemmentioning

confidence: 99%

“…Solving Eqs (5) with the boundary conditions ( 7)- (8) gives the following results for the amplitudes of…”

Section: Determination Of High-frequency Fields In a System With Disp...mentioning

confidence: 99%

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Equilibrium of a toroidal pinch in a static magnetic field and in a high-frequency large-amplitude field

Gutkin¹,

Lozovsky²

1974

Nucl. Fusion

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The authors consider the equilibrium confinement of a toroidal plasma pinch in a static magnetic field and in a high-frequency large-amplitude field in the general case where the gas-kinetic plasma pressure NT is comparable with the pressure of the high-frequency field . It is assumed that the high-frequency field in the range of frequencies 1-10 MHz has a helical or multipole configuration and is excited by given external high-frequency currents passing through the current sheath surrounding the pinch.At high amplitudes of the high-frequency field, it is necessary to allow for the effect of the toroidicity of the system on the equilibrium conditions. In a first approximation with respect to the small parameters Δ/rp and rp/R (Δ is the displacement, rp is the radius of the pinch, R is the major radius of the torus) expressions are found for the high-frequency fields in a system with a displaced pinch and the condition for equilibrium of the pinch as a whole along the major radius is obtained. The equilibrium displacement of the pinch is determined from this condition, making use of the field values of the first approximation at the plasma boundary.It is shown that the use of high-frequency large-amplitude fields offers additional possibilities of controlling the equilibrium displacement. In particular, the effect of the toroidicity of the high-frequency field leads to the occurrence of an additional foree, which in a number of cases causes the pinch to be displaced to the inner wall of the toroidal chamber. When , it is also possible to have a paramagnetic effect when the pinch is forced out by a non-uniform static field towards the side where the intensity of the field is higher, i.e. to the inner wall of the torus. Under certain conditions the phenomena making positive or negative contributions to the equilibrium displacement of the pinch may be mutually compensating, so that the displacement can be made fairly small or even eliminated by suitable choice of the system parameters.The minimum displacement of the pinch for a given amplitude of the high-frequency current in the circuit practically always occurs in the case of quadrupole systems.It is shown that equilibrium confinement of plasma by high-frequency fields is also possible in systems where the plasma pinch is surrounded by a continuous conducting shell (so-called "high-frequency tokamak").The theoretical results obtained are in agreement with the results of experimental investigations.

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Section: Discussion Of the Resultssupporting

confidence: 85%

Section: Statement Of the Problemmentioning

confidence: 99%

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Equilibrium of a toroidal pinch in a static magnetic field and in a high-frequency large-amplitude field

Gutkin¹,

Lozovsky²

1974

Nucl. Fusion

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“…(a) Steady fields Substituting in the first approximation equilibrium condition (3. 10) the values found for the steady (10) and perturbed (11) high-frequency fields with r = a, and also the pressure perturbations and constant magnetic field perturbations from Shafranov's work [19], we obtain, after simple but rather cumbersome calculations, the dispersion equation (3.11) given in the text.…”

Section: Discussionmentioning

confidence: 62%

“…4. The application of a method for dynamic stabilization of the plasma [5][6][7][8][9][10][11]. Systems relying on dynamic stabilization are currently known as hybrid systems; in these the confinement functions are fulfilled by constant magnetic fields and the stability enhancement functions by high-frequency fields of various configurations.…”

Section: Introductionmentioning

confidence: 99%

Dynamic stabilization of magnetohydrodynamic instabilities by means of multipole high-frequency fields

Sidorov

Soldatenkov

1972

Nucl. Fusion

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This article is devoted to problems of stability in a plasma column which has a hybrid current (constant and variable in time) flowing through it. The variable component of the current is, generally speaking, a helical multipole with zero skin layer. The constant current component exhibits either a skin effect or a uniform distribution over the column cross-section. The perturbations considered here are of the surface-wave type, since it is known that this type of perturbation plays a major role in a current plasma with a free boundary.Analysis of the dispersion equation obtained indicates that the application of high-frequency multipole fields reduces the critical q-value in current systems. From the physical point of view, stabilization is brought about by the presence of a time-averaged magnetic well and by the effect of dynamic shear. It was found that the effectiveness of stabilization increases as the multipolarity of the high-frequency field, a fact which is explained by increased depth (on average) of the magnetic well. This requires an increase in the radio-frequency circuit currents, however, which means that circuits with a high Q-factor must be used.The authors also show to what extent the high-frequency circuit (helical conductors) can assume the role of a stabilizing sheath. In the model adopted here the circuit is taken to be an anisotropically conducting sheath and the helical pattern is reflected; perturbations are found on which the circuit exercises a stabilizing effect. These are perturbations whose helix coincides with that of the high-frequency circuit currents projected on a cylindrical plasma surface of radius “a”. All other perturbations remain unaffected by the circuit: the perturbed currents do not form a circuit because the helices of the perturbation and the circuit are crossed.

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The flute instability of a plasma driven by the electrostatic high-frequency eigenmodes

Kopecký

Preinhaelter

1979

Czech J Phys

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Effect of high-frequency electromagnetic field on the stability of a slightly nonhomogeneous magnetized plasma

Cited by 4 publications

References 2 publications

Equilibrium of a toroidal pinch in a static magnetic field and in a high-frequency large-amplitude field

Equilibrium of a toroidal pinch in a static magnetic field and in a high-frequency large-amplitude field

Dynamic stabilization of magnetohydrodynamic instabilities by means of multipole high-frequency fields

The flute instability of a plasma driven by the electrostatic high-frequency eigenmodes

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