Simulation of localized fast-ion heat loads in test blanket module simulation experiments on DIII-D

G.J Kramer,A Mclean,R.V Budny,T Kurki-Suonio,M.J Schaffer,R Nazikian,W.W Heidbrink,K Shinohara,X Chen,J.A Snipes,M.A Van Zeeland,N Brooks,T Koskela

doi:10.1088/0029-5515/53/12/123018

Abstract

Infrared imaging of hot spots induced by localized magnetic perturbations using the test blanket module (TBM) mock-up on DIII-D is in good agreement with beam-ion loss simulations. The hot spots were seen on the carbon protective tiles surrounding the TBM as they reached temperatures over 1000 °C. The localization of the hot spots on the protective tiles is in fair agreement with fast-ion loss simulations using a range of codes: ASCOT, SPIRAL and OFMCs while the codes predicted peak heat loads that are within 30% of the measured ones. The orbit calculations take into account the birth profile of the beam ions as well as the scattering and slowing down of the ions as they interact with the localized TBM field. The close agreement between orbit calculations and measurements validate the analysis of beam-ion loss calculations for ITER where ferritic material inside the tritium breeding TBMs is expected to produce localized hot spots on the first wall.

Highlights

Tritium breeding is of paramount importance for a viable fusion reactor
These test blanket module (TBM) contain a significant amount of ferritic steel, and the TBMs will create three highly localized distortions of the magnetic field which can reduce the confinement of fast ions, especially the fusion-born alpha particles
It was shown from alpha-particle confinement simulations for ITER that a substantial fraction of the lost alpha particles is deposited on the surface of the TBMs thereby creating hot spots [1,2,3,4]

Summary

Introduction

As part of the ITER mission tritium breeding will be studied in six test blanket modules (TBMs) which will be mounted pair-wise in three equatorial ports These TBMs contain a significant amount of ferritic steel, and the TBMs will create three highly localized distortions of the magnetic field which can reduce the confinement of fast ions, especially the fusion-born alpha particles. Good agreement between the measured and modelled thermocouple temperature response was found, there were still questions about possible heat-load contributions from the thermal plasma and of the precise shape of the hot spot on the tiles In those studies four fast-ion transport codes were used, the ASCOT code [6], the DELTA5D Monte Carlo code [7], the OFMC code [8, 9] and the SPIRAL code [10]. The codes gave very similar answers for the total power deposited in the TBM hot spots coming from particles deposited near

Methods

Findings

Discussion

Conclusion