Forced flow cryogenic cooling in fusion devices: A review

Abstract

The constantly increasing energy consumption along with the depleting fossil fuel resources as well as owing to the fact that the nuclear fission not being an intrinsically safe method of energy generation, it has become necessary to look for other solutions to fulfil the future energy demands. Nuclear fusion, the source of energy for billions of stars, has attracted the attention of scientists and engineers despite a lot of technical challenges in the replication of the fusion process in laboratories. For fusion to take place in a device, one of the major challenges faced is the strong magnetic confinement of the plasma using large superconducting (SC) magnets, which need efficient cryogenic cooling techniques to maintain the required low temperatures for the superconducting state. In order to maintain the compactness, the SC magnets generally employ Cable in Conduit Conductor (CICC) windings, carrying high current densities, which are cooled by the forced flow of helium at ~4 K temperature to maintain the required superconducting temperatures. The construction of CICC aims to maintain the superconductivity state by optimization of various parameters such as thermal stability, the ratio of normal conductor to SC material, mechanical strength, low hydraulic impedance, current density, magnetic field, etc. The cryogenic thermal stability of the CICC is of prime importance for safe, stable and reliable operation of SC magnets. The prediction of thermal and hydraulic behavior of the CICC in large SC magnets is difficult due to the complex geometry involved, the variation in fluid properties, various heat in-flux incidences over the long length of CICC and a complex heat transport phenomenon. Another application which utilizes a forced flow cryogenic cooling in the fusion devices is a cryo-adsorption pump for creating clean and high vacuum with large pumping speed. This paper presents an overview of the forced flow cryogenic cooling schemes in fusion devices along with a systematic review of the thermal and hydraulic studies related to CICC and cryo-adsorption pump, thereby highlighting the challenges and opportunities for further improvement in their design and performance.

Conceptual Design of Fusion Power Complex with Hydrogen Storage Function in Superconducting Magnet System

“…Note: Values in parentheses are the facility capacity of the helium gas tanks. 1) value is taken from [4], 2) value is estimeted from [5], 3) value is estimated from [6] table 7.…”

“…Table 1 shows the helium inventories of superconducting magnets and peripheral equipment in major fusion experimental devices currently in operation or under construction. The numbers in parentheses indicate the facility capacity of gas tanks in helium facilities [3][4][5][6] Currently, 27 tons of helium are used in ITER. Based on the volume of the device, the amount of helium required is estimated to be more than double for JA DEMO [7] and the fusion reactors that will be built after ITER.…”

Design and Analysis of a Cooling System for the REBCO Coil Based on GM/JT Cycle

“…Achieving stability in superconducting magnets relies heavily on the management of an appropriate cryogenic cooling system. This system must effectively handle static and pulsed heat loads, as well as other energy inputs, to keep the conductors in a superconducting state [14]. Although immersion in cryogenic liquid can carry most heat away from the REBCO coils, the temperature distribution heterogeneity caused by poor longitudinal conduction still limits the thermal stability of the REBCO coils.…”