Low-aspect-ratio stellarators with planar coils

Moroz, Paul

doi:10.1088/0741-3335/39/11/006

Cited by 9 publications

(15 citation statements)

References 27 publications

(77 reference statements)

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“…Starting in the mid-1990's, Moroz numerically investigated several non-interlinked configurations [18,19,20,21,22,23,24,25]. In some of them the coils were planar [18,19,22], including non-circular shapes [18,22]. In others they were non-planar [20,21,23,24,25,26], e.g.…”

Section: Brief Review Of Tilted Coil Devicesmentioning

confidence: 99%

Large vacuum flux surfaces generated by tilted planar coils

Austin

Hammond

et al. 2019

Plasma Phys. Control. Fusion

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Helical equilibria can be generated by arrangements of planar coils similar to tokamaks, but without a central solenoid and with the toroidal field (TF) coils tilted with respect to the vertical. This is known from earlier numerical works, e.g. P.E. Moroz, Phys. Plasmas 2, 4269 (1995). However, such concept tends to need large coils (of low aspect ratio) but form small plasmas (of large aspect ratio). Here it is numerically shown that larger, more attractive vacuum flux surfaces -relative to the size of the device-can be generated by carefully optimizing the inclination of the TF coils and currents in the various coil-sets. Vacuum configurations of aspect ratios as low as 4 are found for 6 tilted TF circular coils. Higher numbers of TF coils have advantages (smaller effective ripple) and disadvantages (lower rotational transform, smaller plasma). Finally, the aspect-ratio A of the vacuum flux surfaces is quantified as a function of the ratio A c of the coil-radius to the radial location of the coil-center. It is found that, in order to minimize A, it is beneficial to interlink or marginally interlink the TF coils (A c 1).

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Section: Brief Review Of Tilted Coil Devicesmentioning

confidence: 99%

Large vacuum flux surfaces generated by tilted planar coils

Austin

Hammond

et al. 2019

Plasma Phys. Control. Fusion

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“…Devices obtained giving a uniform tilt to the coil so that it preserves its planarity have also been proposed and studied [14][15][16][17][18]. Numerical simulation and preliminary experimental results indicate that these "tokamak-torsatron" hybrid devices can generate rotational transform with less plasma current than conventional tokamaks, if not zero current at all, with interesting implications for disruptions and steady-state operation.…”

Section: Introductionmentioning

confidence: 99%

The differentially-tilted toroidal field coil concept for tokamaks

Gatto

Bombarda

2019

Fusion Engineering and Design

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The implications of the adoption of a tokamak's toroidal field coil characterized by differential tilting in the azimuthal direction are investigated. From an engineering point of view, the major advantage introduced by such coils is a drastic reduction of some components of the electromagnetic forces in certain areas. As a beneficial side-effect, they generate poloidal field, in addition to toroidal field. The former advantage allows for a partial relaxation of the reinforcing structural material required in the machine design, while the poloidal flux generated during the current rise, when used in conjunction with the conventional central solenoid, would allow for discharges of longer duration. This paper presents results obtained by applying the tilting optimization procedure to circular and D-shaped coils, and characterized by geometrical and physical parameters proper of high-field compact tokamaks, since the issue of electromagnetic force reduction is most relevant in these devices.

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“…Note that, to generate rotational transform, it suffices to tilt the coils. Having them interlinked helps to lower the aspect-ratio of the plasma, but is not strictly required [6]. Such a configuration still requires a vertical field for radial force balance and might require an induced or driven plasma current Ip, like a tokamak.…”

Section: Introductionmentioning

confidence: 99%

Proto-CIRCUS tilted-coil tokamak–torsatron hybrid: Design and construction

Clark

Doumet

Hammond

et al. 2014

Fusion Engineering and Design

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We present the field-line modeling, design and construction of a prototype circular-coil tokamak-torsatron hybrid called Proto-CIRCUS. The device has a major radius R = 16 cm and minor radius a < 5 cm. The six "toroidal field" coils are planar as in a tokamak, but they are tilted. This, combined with induced or driven plasma current, is expected to generate rotational transform, as seen in field-line tracing and equilibrium calculations. The device is expected to operate at lower plasma current than a tokamak of comparable size and magnetic field, which might have interesting implications for disruptions and steady-state operation. Additionally, the toroidal magnetic ripple is less pronounced than in an equivalent tokamak in which the coils are not tilted. The tilted coils are interlocked, resulting in a relatively low aspect ratio, and can be moved, both radially and in tilt angle, between discharges. This capability will be exploited for detailed comparisons between calculations and field-line mapping measurements. Such comparisons will reveal whether this relatively simple concept can generate the expected rotational transform.

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Low-aspect-ratio stellarators with planar coils

Cited by 9 publications

References 27 publications

Large vacuum flux surfaces generated by tilted planar coils

Large vacuum flux surfaces generated by tilted planar coils

The differentially-tilted toroidal field coil concept for tokamaks

Proto-CIRCUS tilted-coil tokamak–torsatron hybrid: Design and construction

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