Simply Connected High-β Magnetic Configurations

Rogier, François; Bracco, G.; Mancuso, Alessandro; Micozzi, P.; Alladio, F.

doi:10.1063/1.1593991

Cited by 9 publications

(18 citation statements)

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“…The resulting formation mechanism is similar to PROTO-SPHERA, although the astrophysical phenomena occur at much larger magnetic Lundquist numbers and span a wide range of β values (β « 1 in the solar corona, β ď 1 in collapsing magnetized clumps inside giant molecular clouds, β >> 1 in protostar magnetized accretion disks) [24]. Finally, PROTO-SPHERA could sustain a Chandrasekhar-Kendall-Furth (CKF) magnetic configuration [39], which is a novel approach to magnetic confinement. CKF configurations are simply connected axisymmetric plasma equilibria containing a magnetic separatrix with ordinary X-points (B ‰ 0), which divides a main spherical torus and two secondary tori (on top and bottom) surrounded by a spheromak discharge.…”

Section: Physical Basis and Expected Plasma Evolutionmentioning

confidence: 95%

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Progress of the Plasma Centerpost for the PROTO-SPHERA Spherical Tokamak

et al. 2016

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Plasma properties can be useful in a wide spectrum of applications. Experimental projects on controlled nuclear fusion are the most challenging of these applications and, at the same time, the best way to approach plasma science. Since nuclear fusion reactors can ensure a large-scale, safe, environmentally-friendly and virtually inexhaustible source of energy, several fusion-oriented megaprojects and innovative companies are appearing all over the world. PROTO-SPHERA (Spherical Plasma for HElicity Relaxation Assessment) is the first plasma project with a simply connected configuration, namely not requiring additional objects inside the plasma volume. This is obtained by a plasma arc, shaped as a screw pinch, acting as the centerpost of a spherical torus with minimal aspect ratio. Due to its intrinsic physical, engineering and economic advantages, this new approach is attractive also on an industrial scale and with several developments that still needs to be explored. This paper presents the PROTO-SPHERA basic principles, its first encouraging results and its expected and potential evolutions.

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Section: Physical Basis and Expected Plasma Evolutionmentioning

confidence: 95%

“…As a possible far-future development, it should be stressed that a simply connected configuration is particularly suitable for magnetic fusion space propulsion [38,39]. Finally, it is noteworthy that some recently announced machines can even be regarded as a sort of PROTO-SPHERA configuration with some fluctuating coils [18].…”

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confidence: 99%

Progress of the Plasma Centerpost for the PROTO-SPHERA Spherical Tokamak

et al. 2016

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“…where γ is the superposition coefficient, has been dubbed (Rogier et al 2003) the Chandrasekhar-Kendall-Furth force-free field (CKF), for being based on particular equilibrium solutions from Chandrasekhar & Kendall (1957) and Furth et al (1957). The shape of CKF configurations does not depend on the poloidal current parameter; in fact μ variations are equivalent to rescaling both R and Z with the same factor.…”

Section: The Chandrasekhar-kendall-furth Modelmentioning

confidence: 99%

“…The superposition of (5.5) and (5.7), where is the superposition coefficient, has been dubbed (Rogier et al. 2003) the Chandrasekhar–Kendall–Furth force-free field (CKF), for being based on particular equilibrium solutions from Chandrasekhar & Kendall (1957) and Furth et al. (1957).…”

Section: Axially Bounded Equilibrium Modelsmentioning

confidence: 99%

“…where n is a separation parameter. With the change of variable ψ n2 = (1 − x 2 ) 1/2 p(x), the angular part of (5.2) becomes a general Legendre equation of degree n and order 1, with solution p(x) = −P 1 n (x), where the negative sign is used for consistency with Rogier et al (2003). For integer n the angular dependence becomes a combination of Legendre polynomials:…”

Section: Solutions In Spherical Coordinatesmentioning

confidence: 99%

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Analytical studies of PROTO-SPHERA equilibria

et al. 2020

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Analytical solutions of the Grad–Shafranov equilibrium equation in simply connected plasma configurations, comprised of toroidal magnetic surfaces and open surfaces connected to electrodes, are reviewed and generalised. The Grad–Shafranov equation is linearised introducing assumptions on plasma current and pressure, which preserve regularity of solutions on the symmetry axis, as required for a simply connected geometry. Particular solutions are found by separation of variables both in cylindrical coordinates and in spherical ones. Equilibria that model local or global features of PROTO-SPHERA plasmas are constructed by combining a few particular solutions.

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Proposed Experiment to Study Relaxation Formation of a Spherical Tokamak with a Plasma Center Column

Hsu

Tang

2006

J Fusion Energ

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A spherical tokamak (ST) with a plasma center column (PCC) can be formed via driven magnetic relaxation of a screw pinch plasma. An ST-PCC could in principle eliminate many problems associated with a material center column, a key weakness of the ST reactor concept. This work summarizes the design space for an ST-PCC in terms of flux amplification, aspect ratio, and elongation, based on the zero-β Taylor-relaxed analysis of Tang & Boozer [Phys. Plasmas 13, 042514 (2006)]. The paper will discuss (1) equilibrium and stability properties of the ST-PCC, (2) issues for an engineering design, and (3) key differences between the proposed ST-PCC and the ongoing Proto-Sphera effort in Italy. PACS numbers: 1 I.

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Simply Connected High-β Magnetic Configurations

Cited by 9 publications

References 0 publications

Progress of the Plasma Centerpost for the PROTO-SPHERA Spherical Tokamak

Progress of the Plasma Centerpost for the PROTO-SPHERA Spherical Tokamak

Analytical studies of PROTO-SPHERA equilibria

Proposed Experiment to Study Relaxation Formation of a Spherical Tokamak with a Plasma Center Column

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