Alpha-Physics and Measurement Requirements for ITER

The temporal evolutions of the operating point during the ignition access and ignited operation phases are analysed on the basis of zero dimensional (O-D) equations in order to clarify the requirements for safe control of ignited operation and for the development of diagnostic systems in ITER. A stable and safe method of reaching the ignited operating point is identified as the `higher temperature access' method, being compatible with the H mode power threshold constraints. It is found that the ignition boundary can be experimentally determined by a `thermonuclear oscillation' of the operating point without knowing the power balance equation. On the other hand, the ignition boundary determined by the power balance equation has a larger error bar depending on the accuracy of the diagnostic system. The plasma waveform response to sudden changes in the various plasma parameters during ignited operation is also calculated, and fusion power regulation is demonstrated by feedback control of the fuelling and auxiliary heating power

Section: 411mentioning

confidence: 99%

Ignition analysis for burn control and diagnostic developments in ITER

Mitarai

Muraoka

1997

“…To overcome this situation, we propose to occupy the one toroidal section for measuring the alpha loss distribution poloidally with a set of neutron resistant thin foil Faraday collectors [34]. Various burn conditions should be tried to correlate between the alpha loss and infrared TV camera temperature measurements [35]. After establishing this correlation, the lost alpha detectors can be removed.…”

Section: Discussion On Diagnosticsmentioning

confidence: 99%

A proposed set of diagnostics for core ignition burn control in a tokamak reactor

Mitarai¹,

Muraoka²

1999

A set of diagnostic systems essential for core ignition burn control in future tokamak fusion reactors, including ITER, has been developed. This diagnostic set is based on examination of various feedback control algorithms in the ignition access, steady state and shutdown phases of ignition burn in the plasma core. The control algorithms used here are based on a combination of H mode power threshold and fusion power. The external heating power is determined either by the H mode power threshold or the fusion power, and the fuelling rate by the fusion power. From over-ignition to subignition, these algorithms sufficiently control all the core burn condition, such as the sudden change in various plasma parameters, as demonstrated numerically. A feedback control diagram is presented for achieving burn control consisting of, for example, measurements of line averaged density, net alpha heating power, bremsstrahlung loss and the synchrotron radiation loss.

“…A consideration of alpha particle physics issues in ITER indicates the need for measurements of alpha instabilities, confined alphas, and lost alphas, and suggests measurement requirements and possible techniques [39]. Alpha heat losses and instabilities manifest themselves indirectly by giving rise to local hot spots on the first wall, observable with infrared cameras and thermocouples, and to plasma fluctuations, observable by magnetic loops, reflectometry, etc.…”

Section: Fusion Product Measurementsmentioning

confidence: 99%

“…The technique is still under development [40,41] and it may be able to meet some of the ITER require-ments. An improvement in the measurement capability for escaping alpha particles is also required, and a device that can potentially be applied to ITER is under development [39]. For some parameters, an improvement in the measurement capability is required but no new techniques are presently under development.…”

Section: Development Of Diagnostic Components and New Concept Diagnos...mentioning

confidence: 99%

Chapter 7: Measurement of plasma parameters

Diagnostics¹,

Editors²

1999

The physics issues of the measurements of the plasma properties necessary to provide both the control and science data for achieving the goals of the ITER device are discussed. The assessment of the requirements for these measurements is first discussed, together with priorities that relate to the experimental program. Subsequently, some of the proposed measurement techniques, the plasma diagnostics, are described with particular emphasis on their implementation on ITER and their capability to meet the requirements. A judgement on the present status of the diagnostic program on ITER is provided with some indication of the research and development program necessary to demonstrate viability of techniques or their implementation.