On the other hand, also the physics development of steady-state operation at high plasma performance poses a challenge and careful preparation.
However, designing a stellarator presents several challenges. The sole use of coils to create a magnetic trap usually entails complex
A Dual Coolant Lithium–Lead Breeding Blanket is explored for an HELIAS. A “quasi-toroidal” BB segmentation has been proposed to minimize MHD pressure drop.
In this context, we proposed the PM4Stell project to determine the feasibility of the concept by designing and constructing a prototype array of permanent magnets for a stellarator, and confirming the accuracy of the field through direct measurements. 2.1 Magnet system design The central challenge of the design of the magnet array for PM4Stell was to arrive at a solution that could produce the required magnetic field for a given stellarator plasma with sufficient accuracy, while also being feasible to fabricate and assemble within a mounting structure that could handle the electromagnetic and gravitational loads arising from the magnets. Once the main magnet array is constructed and its field is measured (Sec. 2.4), the required polarizations and locations for the error-correcting magnets can be determined using the essentially the same procedure 6 Figure 2.3: Positions of the magnets in one half-period of the solution for PM4Stell, color-coded according to the polarization types identified in Fig. 2.1.
The point is stellarators are particularly complicated and non-intuitive. Their 3D geometry is harder understand, design, and build. You really need a
Overall the potential of the computationally intensive field of turbulent transport optimization is extremely high, as new simulation tools offer the possibility of designing the full transport properties—both neoclassical and turbulent—into the configuration and producing systems with significantly better plasma confinement than is presently accessible in either tokamaks or stellarators. The major topics are summarized here: 51 Quasi-symmetric (QS) magnetic configurations • The US leads the world in the design of quasisymmetric stellarators, which are compatible with steady state operation and that possess good neoclassical confinement and are stable at high plasma pressure Non-resonant Divertors • The non-resonant divertor concept has great potential and represents an opportunity for US leadership in divertor science and is complimentary to other divertor concepts being investigated on LHD and W7-X Turbulence and Transport • Advances in gyrokinetic codes have furnished new capabilities for nonlinear simulation of microinstabilities in the fully 3D toroidal equilibria of stellarators.
Although the primary objective in this manuscript is to use these objectives to show plausible dipole coil array solutions for three reactor-scale stellarators, there remain open questions about the robustness of the conclusions in this section about force and torque minimization across different stellarator devices, coil sets, and different initial conditions for optimization. * By minimizing pointwise forces and net torques directly, the total TF coil lengths from optimization (1) to (2) are reduced by more than 20 m at the same time that peak dipole currents increase by an order of magnitude, net torques reduce by an order of magnitude, and maximum pointwise forces stay within a factor of two. We use the force and torque optimized dipole array solution as an initial condition for an additional optimization with TF coils slightly increased to 90.1 m, still saving 32km of superconductor compared to the published modular coil solution.
Stellarators behave better. Like tokamaks they're doughnut shaped, but stellarator magnets are arranged to confine the plasma without needing a plasma current.