Magnetic diagnostics for ITER/BPX plasmas (invited)

Abstract

The measurement requirements and expected performance of the International Thermonuclear Experimental Reactor (ITER) magnetics system are summarized. The constraints of a burning plasma experiment (BPX) on tokamak magnetic diagnostic system designs are listed and illustrated using the parameters and design of sensors being developed for the ITER device. Design principles to meet the constraints are discussed, with an emphasis on radiation effects, reliability, and redundancy for sensors and subsystems. The remaining research and development for the ITER system is outlined.

In situ “artificial plasma” calibration of tokamak magnetic sensors

“…The techniques described here may be relevant to devices with large diagnostic sets such as ITER 22 or to long-pulse devices such as W7-X 5 where eddy current effects will be significant, due to the need for in-vessel active cooling components with high thermal and electrical conductivity and non-trivial geometries. The implementation of an artificial plasma system on such future devices can be optimized in several manners.…”

The magnetic diagnostic set for ITER

“…The detailed requirements for the magnetic sensors needed to meet the purposes of this diagnostic system in ITER are well established [3], [4] and are briefly summarized in Table I together with the main risks that could prevent the achieving of the intended goals. These requirements cover measurement capabilities, diagnostic functionalities, and safety and are overviewed in the next sections.…”

“…The design of the individual sensors themselves has to cope with maintenance-free operation during the lifetime of the ITER project, even though some of the components are intended to be designed with the possibility of remote maintenance. Therefore, the principal challenges to this diagnostic to meet the ITER measurement requirements [3], [4] are as follows: 1) meeting the requirements to identify the small lowwavelength perturbations; 2) guaranteeing appropriate sensitivity in the presence of massive passive structures; 3) guaranteeing the frequency response of the sensors and, at the same time, meeting the sensitivity requirement; 4) meeting the environmental conditions of radiation, thermal, and mechanical stresses; 5) meeting the high level of reliability compatible with the low-maintenance requirement. As reported in [14]- [18], technical solutions for the design and construction of the sensors themselves have been explored, and adequate solutions are considered to exist, although there is no design fully accepted as of today.…”

“…The formal ITER measurement requirements for the full magnetic diagnostic set are presented in [3] and [4]. Fig.…”

Diagnostics for steady state plasmas

“…Mineral insulated (MI) coax cables are typically used in radiation environments [282]. In the field of ionizing radiation they must accommodate radiation induced currents and voltages representing additional noise, introducing in particular measuring errors.…”