In this study, the concept of a spherical tokamak with non-inductive current drive to be realized by an alternative method is presented. The analytical model of this conceptual design is a combination of peculiarities based on current drive by helicity injection as developed by Taylor and a spherical torus plasma with small aspect ratio (A between 1.2 and 2), and naturally large elongation (k in the range of 1.25 and 3) with an edge safety factor q_a between 1.5 and 4. The numerical scheme used in this computational experiment is constituted by the analytical expressions given by Peng and Wilson. In addition, the bootstrap current drive mechanism is also taken into consideration. These models are interactive. In the proposed system, a simulated single turn, very high current, toroidal field coil is controlled by a magnetically driven C-gun. The main part of the toroidal field coil consists of a shock heated, time varying, non-linear plasma belt in the flux conserver and a complementary back strap outside. The poloidal current loop is completed by a spark gap switch and a capacitor bank. The complete spherical torus plasma is formed by a multisegmented 24 C-guns system around the flux conserver. Because of the temperature and density gradients of these belts, pushed towards the centre of the flux conserver by the Lorentz forces, either toroidal or poloidal bootstrap currents are generated. On the other hand, helicity injection of the C-guns creates a second current drive mechanism. Consequently, a low aspect ratio, large elongated and strong paramagnetic spherical tokamak plasma is produced.
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