Chapter 7: Diagnostics

Abstract

In order to support the operation of ITER and the planned experimental programme an extensive set of plasma and first wall measurements will be required. The number and type of required measurements will be similar to those made on the present-day large tokamaks while the specification of the measurements-time and spatial resolutions, etc-will in some cases be more stringent. Many of the measurements will be used in the real time control of the plasma driving a requirement for very high reliability in the systems (diagnostics) that provide the measurements.The implementation of diagnostic systems on ITER is a substantial challenge. Because of the harsh environment (high levels of neutron and gamma fluxes, neutron heating, particle bombardment) diagnostic system selection and design has to cope with a range of phenomena not previously encountered in diagnostic design. Extensive design and R&D is needed to prepare the systems. In some cases the environmental difficulties are so severe that new diagnostic techniques are required.The starting point in the development of diagnostics for ITER is to define the measurement requirements and develop their justification. It is necessary to include all the plasma parameters needed to support the basic and advanced operation (including active control) of the device, machine protection and also those needed to support the physics programme. Once the requirements are defined, the appropriate (combination of) diagnostic techniques can be selected and their implementation onto the tokamak can be developed. The selected list of diagnostics is an important guideline for identifying dedicated research and development needs in the area of ITER diagnostics.This paper gives a comprehensive overview of recent progress in the field of ITER diagnostics with emphasis on the implementation issues. After a discussion of the measurement requirements for plasma parameters in ITER and their justifications, recent progress in the field of diagnostics to measure a selected set of plasma parameters is presented. The integration of the various diagnostic systems onto the ITER tokamak is described. Generic research and development in the field of irradiation effects on materials and environmental effects on first mirrors are briefly presented. The paper ends with an assessment of the measurement capability for ITER and a forward of what will be gained from operation of the various diagnostic systems on ITER in preparation for the machines that will follow ITER. Performance assessment relative to requirements Design meets requirements S339 A.J.H. Donné et alPhysics Basis [7] and remains essentially the same. However, for ITER, the specific limits have changed. 2.1.2.Measurements needed for plasma control and evaluation. The measurements needed for plasma control and evaluation are naturally directly linked to the experimental programme, and particularly to the operating phase (i.e. H, D or D/T) and the operating scenario (H-mode, hybrid, etc). Since there is expected to be a phased introduction of po...

Validation metrics for turbulent plasma transport

“…This propagation can be achieved in principle through the computational fitting routines themselves, or more commonly by a Monte Carlo approach in which ensembles of data points are generated by randomly varying each point in proportion to the quoted uncertainty, and then generating corresponding ensembles of fits. Measurement of different kinetic profiles requires use of different diagnostic techniques, 109,110 such as Thomson scattering, reflectometry, electron cyclotron emission (ECE), charge exchange recombination (CER), Xray crystal spectroscopy (XCIS), and motional Stark effect polarimetry (MSE). Each such technique has its own challenges and uncertainties that must be understood and incorporated for this uncertainty quantification approach to be meaningful.…”

Short wavelength far infrared laser polarimeter with silicon photoelastic modulators

“…In ITER, the maximum Faraday rotation angle is about 14°for 57.2 m light in the case of the density profile of 1 ϫ 10 20 ͑1− 8 ͒ m −3 . Considering that a required temporal resolution is 10 ms for equilibrium analyses in ITER 28 and the q-profile recovery error mentioned above, the present resolution is preferable to the equilibrium analyses. For measurements of magnetic field fluctuations, 16 improvement of the temporal resolution is necessary.…”

Extended calculations of energy levels, radiative properties, A, B hyperfine interaction constants, and Landé g -factors for oxygen-like Kr XXIX

“…As a rare gas, Krypton can easily be introduced into the plasma and does not pollute the vacuum vessel. For this reason it is widely used as an injected impurity for diagnosing tokamak fusion plasmas [1][2][3]. To analyze the observations of Kr ions, accurate atomic parameters including energies, transition rates, and lifetimes, are required.…”