Liquid first walls for magnetic fusion energy configurations

Abstract

Liquids (~7 neutron mean free paths thick), with certain restrictions, can probably be used in magnetic fusion designs between the burning plasma and the structural materials of the fusion power core. If this works there would be a number of profound advantages: a cost of electricity lower by as much as a factor of 2; removal of the need to develop new first wall materials, saving over 4 billion US dollars in development costs; a reduction of the amount and kinds of wastes generated in the plant; and the wider choice of materials permitted. The amount of material that evaporates from the liquid which can be allowed to enter the burning plasma is estimated to be less than 0.7% for lithium, 1.9% for Flibe (Li2BeF4 or LiBeF3) and 0.01% for Li17Pb83. The ability of the edge plasma to attenuate the vapour by ionization appears to exceed this requirement. This ionized vapour would be swept along open field lines into a remote burial chamber. The most practical systems would be those with topological open field lines on the outer surface, as is the case with a field reversed configuration (FRC), a spheromak, a Z pinch or a mirror machine. In a tokamak, including a spherical tokamak, the field lines outside the separatrix are restricted to a small volume inside the toroidal coil making for difficulties in introducing the liquid and removing the ionized vapour, i.e. the configuration is not open ended

Qualitative Reliability Issues for Solid and Liquid Wall Fusion Design

“…It is possible that a nozzle could erode at its opening, allowing mist or droplet formation, which would be very detrimental to plasma operation, and could lead to plasma disruptions. The nozzle 'mouths' would need periodic inspections and possible replacement (Moir, 1997). If the nozzles were required to oscillate for coverage, then the nozzle oscillation mechanisms would also require periodic inspection and testing, since the interior of a tokamak is known to be a harsh environment for wear (Marmy, 1990).…”

Novel liquid blanket configurations and their hydrodynamic analyses for innovative confinement concepts

“…A 2-D (r-q) linear stability analysis is performed using an irrotational velocity profile with surface tension, gravitational acceleration and the centrifugal acceleration models. Assumptions are: (1) boundary layer thickness is small compared to the free stream thickness; (2) only azimuthal velocity components are taken into account; (3) initial infinitely small perturbations are introduced for surface displacement and velocity potential. The system equations are: Laplacian of velocity potential and Bernoulli Equation with surface tension, centrifugal acceleration and gravitational acceleration models for a finitely small disturbance in the surface perturbation and velocity potential are expressed respectively as,…”

“…The present thick liquid FW/blanket idea for field reversed configuration (FRC) and spherical torus (ST) configurations evolved from the thick liquid wall (TLW) concepts proposed by Moir [1,2] for magnetic fusion energy configurations. The idea is now being investigated, modified and developed in the APEX (advanced power extraction) study [3], which is aimed at exploring innovative concepts of handling high power density that may enhance the potential for fusion to be a competitive energy source.…”

Magnetic Diagnostics for Equilibrium Reconstructions in the Presence of Nonaxisymmetric Eddy Current Distributions in Tokamaks

“…The limited viability of traditional materials has led to the investigation of novel first walls, 1,2 including liquid lithium plasma-facing components ͑PFCs͒. 3 The first experiments utilizing lithium began with straightforward wall-conditioning techniques.…”