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

Abstract

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.

High-Density, Low Temperature Ignited Operations in FFHR

“…However, as it is difficult to use the density limit scaling in the unstable operation, the different control algorithm must be developed. In this study we used the fusion power error as used in the ITER ignition study [17]. When the fusion power is smaller than the preset value, the heating power is applied by the following algorithm.…”

Analyses of Diagnostic Failure Effect and Fail-Safe Ignited Operation in a Tokamak Fusion Reactor

“…26 On this basis, the plasma core burn control algorithm was proposed using the external heating power from the H-mode power threshold to keep the H-mode and fueling to keep the fusion power at the desired value. 19,20 This control algorithm to keep such quantities has been confirmed to work well for the case of a sudden change in the plasma parameters, such as a sudden change in the confinement factor, alpha ash confinement time, sudden injection of impurities and ab-sorbed fuels, sudden increase in the alpha-particle loss, etc. 16 We should note that as for the sudden change in the plasma position, although this feedback control has not been tested yet, the same feedback control algorithm for an ignition burn is expected to manage this situation.…”

“…18 This type of analysis on failure modes and effects analyses of each diagnostic system is also necessary for developing a fusion reactor. Recently, burn control diagnostic systems have been proposed based on examination of various control algorithms by authors for a fusion reactor, including ITER, 19,20 which is developed independently of the ITER team. [21][22][23][24][25][26] Based on this work, it is possible to see how the ignited operation behaves after the diagnostic failure.…”

Research on Burn Control of Core Plasma with the Transport Code

“…The diagnostics in the DEMO are discussed in Ref [13] and [14]. The discussion of diagnostics systems through the simulation of burn control is shown in Ref [15]. To discuss the measureable parameters and the parameters which we want to measure, we categorize the goal of the fusion reactor into four items, and list up the parameters associated with them in Table 1.…”