Equilibrium field coils and free-boundary equilibrium considerations for TNS

The Next Step (TNS) tokamak is expected to have a D-shaped plasma to permit MHD stable operation with volume averaged-beta, anti..beta.. up to 10 percent. By following a procedure similar to the method of virtual casing, external coil arrangements were produced that reproduce the ideal vacuum vertical field B/sub z//sup ID/ for a D-shaped plasma to within a few percent root-mean-squared deviation. A typical coil system and a free-boundary equilibrium are shown. It is seen that D-shaped equilibria can be with the external coils. Again, three sets of coils are sufficient for centering and shaping the plasma for the range of anti..beta.. values of interest. It is concluded that placing the equilibrium field coils external to the toroidal field coils has the potential of substantially reducing the cost and complexity of the D-shaped TNS device. (MHR

Hybrid equilibrium field coils for the ORNL TNS

In this study, we make a comparative study of the power supplies required by interior and exterior (to the toroidal field (TF) coils) equilibrium field coils that are separately appropriate for high-..beta.., D-shaped plasmas in TNS. It is shown that the interior coils need power supplies that are an order of magnitude below those required by the exterior coils (while the latter case is much less difficult to build than the former). A hybrid EF coil concept is proposed that combines the interior and the exterior coils to retain their advantages in avoiding large interior coils while lowering the power supplied to the exterior coils by an order of magnitude

Numerical simulation of the plasma current quench following a disruptive energy loss

The plasma electromagnetic interaction with poloidal field coils and nearby passive conductor loops during the current quench following a disruptive loss of plasma energy is simulated. By solving a differential/algebraic system consisting of a set of circuit equations (including the plasma circuit) coupled to a plasma energy balance equation and an equilibrium condition, the electromagnetic consequences of an abrupt thermal quench are observed. Limiters on the small and large major radium sides of the plasma are assumed to define the plasma cross section. The presence of good conductors near the plasma and a small initial distance (i.e., 5 to 10% of the plasma minor radius) between the plasma edge and an inboard limiter are shown to lead to long current decay times. For a plasma with an initial major radius R/sub o/ = 4.3 m, aspect ratio A = 3.6, and current I/sub P/ = 4.0 MA, introducing nearby passive conductors lengthens the current decay from milliseconds to hundreds of milliseconds

Initial results of systems analysis of the ITER design space

This series of vugraphs presents preliminary analyses of various design points for the next generation thermonuclear test reactor. The authors state that constrained optimization of a figure-of-merit leads to acceptable design points. Design points discussed include: device radius, aspect ratio, magnetic field strength, magnet current, plasma current, and ignition margin. (JDH

FED/INTOR reactor design studies

Upon completing the design studies identified in this report, an overall assessment of the design options is made that will form the bases to define the configuration of the next major Tokamak device. The TF coil size will be defined, along with the vacuum boundary, the PF coil arrangement, and the torus configuration. After the configuration is established, an overall performance and cost re-assessment should be made to finally trade off device performance with machine capital and operating costs to establish a reactor design point for a given set of design requirements

Large aspect ratio tokamak study

The Large Aspect Ratio Tokamak Study (LARTS) investigated the potential for producing a viable long burn tokamak reactor through enhanced volt-second capability of the ohmic heating transformer by employing high aspect ratio designs. The plasma physics, engineering, and economic implications of high aspect ratio tokamaks were accessed in the context of extended burn operation. Plasma startup and burn parameters were addressed using a one-dimensional transport code. The pulsed electrical power requirements for the poloidal field system, which have a major impact on reactor economics, were minimized by optimizing the field in the ohmic heating coil and the wave shape of the ohmic heating discharge. A high aspect ratio reference reactor was chosen and configured