A Model for First-Wall Thermal Response to Plasma Energy Deposition (original) (raw)
Related papers
Advanced Methods for the Evaluation of the Heat Flux Distribution onto the First Wall of a Tokamak
Proc. of XXIV Congresso Nazionale UIT sulla …, 2006
We present a new computational code for the evaluation of heat fluxes on the first wall of a tokamak reactor. The method applies the Control-Volumes Finite-Element (CVFE) approach to the solution of the plasma fluid equations on the tokamak edge. The CVFE approach is particularly suited for application to triangular meshes, and allows extending the computational grid up to the physical wall of the reactor. As a consequence, it enables studying the Plasma-Wall Interactions (PWI) in full geometrical detail, as opposed to the presently most popular codes, which oversimplify the external wall shape on most of its extension. The new code was developed to study the heat flux deposition onto the IGNITOR First-Wall/Limiter, but has a number of other potential applications, including the limiter start-up phase of the International Thermonuclear Experimental Reactor (ITER), the power deposition onto the external wall driven by Edge Localized Modes (ELMs). Here we discuss the method, illustrate its geometrical potentialities on a simple test case, and present the first application to the analysis of the IGNITOR tokamak first-wall/limiter.
An Analysis of Bremsstrahlung Energy Deposition in Magnetic Fusion First-Wall Materials
Nuclear technology/fusion, 1984
A model for predicting bremsstrahlung energy deposition in first-wall materials and the effect of this energy deposition on wall temperature distributions is proposed. In this model the bremsstrahlung energy spectrum is divided into a finite number of discrete energy groups, each with an overall power fraction and average wavelength. The volumetric heating effects of each of these individual groups are superimposed to obtain overall temperature distributions in first-wall configurations using rectangular and cylindrical coordinates. The proposed multigroup model is then applied to several first-wall designs and compared with existing models, notably the "surface-heating" model, which utilizes the assumption that the bremsstrahlung energy is deposited on the wall surface. It is concluded that in many designs involving advanced fuels or low-Z first-wall materials the surface-heating model overpredicts wall temperatures near the plasma side, and the multigroup model may be necessary for accurate temperature calculation.
Thermal radiation analysis of DEMO tokamak
Fusion Engineering and Design, 2017
h i g h l i g h t s • Thermal radiation analysis of the DEMO tokamak was performed. • To complement the baseline tokamak model, thermal shields and lower part of the cryostat were newly designed on a conceptual level. • The Finite Element (FE) code ABAQUS was used to perform numerical analyses. • Thermal loading and refrigeration power for the configuration with actively cooled as well as with passive thermal shields was determined.
Plasma Design Considerations of Near Term Tokamak Fusion Experimental Reactor
Journal of Nuclear Science and Technology, 1982
Wide range of parameter surveys are made on the DT fusion tokamak experimental reactor next to JT-60. Various physics and engineering requirements are taken into account, e. g. self-ignition, available maximum toroidal fJ value, a-particle confinement, total fusion power, neutron wall loading, heat flux to divertor plate, structural restriction on major radius, device size, maximum toroidal magnetic field, poloidal field power supply and so on. Theoretical scaling law for the available maximum toroidal fJ value determined by ballooning mode instability is used. The toroidal magnetic field on plasma axis can be expressed by the aspect ratio A for a given maximum field at the toroidal field coil conductor. Empirical scaling law for the electron energy confinement and neoclassical heat conductivity for the ion are employed. These confinement times can be expressed by the plasma minor radius a and A through the maximum available fJ value and the toroidal field on axis. In the similar way, most of the physics and engineering requirements can be mapped on the a-A diagram. This diagram enables us to make systematic and wide range of parameter surveys of the device. In particular, this offers a clear perspective on the device parameters, which can mitigate the engineering difficulties and can also realize the required plasma performances.
2021
The ITER tokamak, the experimental fusion reactor designed to be the first to produce net energy, has had a monoblock concept selected for use as a plasma facing component in the divertor region. This design currently consists of a CuCrZr cooling pipe surrounded by a copper interlayer and embedded in a tungsten armour plate. Additive manufacturing may facilitate a geometry capable of greater efficiency through the introduction of greater design freedom whilst maintaining compatibility with the monoblock concept. This is achieved through the addition of high conductivity material to the armour domain surrounding the coolant pipe. Finite element simulation of the heat transfer system combined with a topology optimisation methodology has been used to find the optimal distribution of high thermal conductivity material (such as Cu) for three thermal objectives: minimising temperature and thermal gradient, and maximising conductive heat flux. The topology optimisation relies on a density-...
Fusion Engineering and Design, 2004
Thermal analysis is a prime consideration in the design of plasma facing components (PFC) cooling during plasma operation in a Tokamak device. The task is greatly simplified by using computer-based numerical techniques. Finite difference method (FDM) and finite element method (FEM) are the two methods generally being used for thermal analysis. FEM is gaining wide acceptance for such problems because it performs all the necessary computations in the computer. FDM, in contrast, requires significant amounts of data to be calculated for input into the computer program. This can provide accurate thermal analysis in less time and less computer memory than FEM. An efficient finite difference (FD) code has been developed to derive the two-dimensional temperature profile in different PFC modules subjected to steady-state condition. The details of the code and comparison of its results with finite element (FE) analysis are presented in this paper.
Designing a tokamak fusion reactor—How does plasma physics fit in?
Physics of Plasmas, 2015
This paper attempts to bridge the gap between tokamak reactor design and plasma physics. The analysis demonstrates that the overall design of a tokamak fusion reactor is determined almost entirely by the constraints imposed by nuclear physics and fusion engineering. Virtually no plasma physics is required to determine the main design parameters of a reactor:
Measurements of the heating beam deposition profile in TFTR (Tokamak Fusion Test Reactor)
1990
The calculated heating-beam deposition profile is experimentally verified for a variety of target plasma densities for the first time. The calculation of the heating-beam deposition is found to be consistent with the measurement for the discharges without MHD activity. It is also demonstrated that the radial electron flux is unchanged from the ohmic phase to the initial auxiliary heating phase (< 100 msec).
Heat and Particle Deposition on the Plasma-Facing Components
The interaction of plasma with plasma-facing components (PFCs) in tokamaks is of increasing interest because of implications for ITER and next-step devices. The heat and particle fluxes interacting with solid objects can be studied by means of particle-in-cell (PIC) simulations. The aim of this work is to use the existing family of PIC codes SPICE to simulate the heat and particle flux distribution on PFCs. The output of the simulations is then used in new heat equation solver, which calculates the temperature of the PFCs. This solver provides us a testbed for the parallel sparse matrix code development as well as for the complex application aimed at study of the melting of tiles.