High magnetic field tokamaks

Abstract

A review of existing high magnetic field tokamaks is presented. The results obtained, especially in the research areas concerning confinement, impurity control and heating, are discussed and compared with those of tokamaks at lower toroidal field. New devices, either proposed or under construction, are surveyed. Advantages and difficulties of such machines in exploring the approach to ignition are examined.

First experiments with lithium limiter on FTU

“…Very promising results have been obtained on T-11M tokamak, encouraging to extend the use of liquid lithium limiter on a more relevant fusion machine. An experimental program on this purpose started at the end of 2005 on FTU [4], an all metallic and carbon free medium size tokamak, with the aim to test for the first time in a high field machine a liquid lithium limiter (LLL) with CPS configuration. This paper describes the experimental results of the first experimental campaign in FTU on some important physical and technological issues such as: (1) the wall conditioning efficiency of lithium to reduce plasma contamination and recycling; (2) the lithium limiter capability to withstand high thermal loads from plasma interaction without surface damage.…”

Effects of wall boron coating on FTU, an all metallic and carbon free medium size tokamak

“…The boronization technique has also been applied on FTU (R = 0.93 m, a = 0.33 m, B T 8 T, total pulse duration t pulse ≈ 1.5 s), which uses a molybdenum alloy (TZM) for the internal toroidal limiter and the external poloidal limiter and stainless steel AISI 304 for the vacuum chamber walls. The first boronization on an all-metallic tokamak was carried out on Alcator C-Mod [7], which belongs to the same class of the high field, high density ( ne > 1 × 10 20 m −3 ) compact devices as the FTU [8] and uses molybdenum as the first wall material. This technique has permitted the production of a stable H-mode transition [9] by reducing carbon and oxygen fluxes coming from the Mo tiles.…”

High Temperature Superconductors

“…A large operating magnetic field range opens new opportunities to fabricate novel magnetic designs and improved magnetic confinement can be achieved for higher magnetic fields (> 16 T) with the help of HTS [99]. A maximum achievable induced field that depends upon current density present in HTSs has been a primary factor in fabrication of magnetic devices for fusion reactors as explained in basic tokamak design, in-depth studies, system codes, and tokamak magnet designs [100]. HTS offers a significant increase (~7.5 to 10-12 T) in on-axis BT in tokamak reactor which allows a significant increase in an applicable field in coil from 16 T to >20 T) as compared to LTS.…”