Spheromak plasma formation

We discuss (1) the theoretical analysis of the spheromak, (recent theoretical studies are summarized and a comparison is made with other approaches), and (2) a spheromak plasma formation scheme. One of the difficult aspects of spheromak research is to produce a toroidal plasma in the absence of coils down the axis of rotational symmetry. A novel plasma formation scheme has been developed at PPPL to create a toroidal plasma by using a flux generating core technique. This formation scheme has been optimized with the assistance of resistive MHD computer codes. The parameters of the S-1 device, now under construction, were determined with various theoretical aids. 

There have been accelerated efforts to investigate the physics problems associated with the spheromak plasma formation schemes, global MHD modes, surface modes, plasma trasport and reactor aspects. The potential advantages of this type of configuration in reactors are large. 

Many theoretical and experimental physics issues concerning the spheromak such as MHD stability, transport phenomena, microinstabilities, and plasma formation schemes had remained virtually unstudied. The reexamination of this configuration from the reactor viewpoint recently became of great interest [5] and the study of these issues has been accelerated, since... 

The reversed field 0 pinch with no toroidal field inside the plasmoid is a more advantageous reactor-oriented device than the spheromak, in some respects, since the plasma formation is... 

If the Princeton scheme turns out to be extendable to a reactor, the core size would be of 4.0m major radius and 0.8 m minor radius. Stored energy would reach up to 4-8 GJ in the flux core, which is not inferior to that of tokamak OH systems and EF systems. However, the main problem may be how slow the formation can be done. In order to compete with tokamak type reactors (which are supposed to increase the plasma current in 1-3 sec. according to the present design), the instantaneous power should be limited to 4-8 GW. Thus, the formation time scale is preferred to be one second. It is obvious that the 100-GJ stored toroidal energy needed in the tokamak is not required in the spheromak reactor. 

The Spheromak has been presented by Dr. M. Okaba-yashi. The toroidal plasma has an aspect ratio not much larger than 1 the complex device proposed for the production of the plasma configuration is hardly compatible with the neutronics associated with the burning phase. Thus it has been proposed to extrude the plasma toroid from the place of formation and guide it magnetically to the place of burning. 

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