Integrated Plasma-material Interaction Analysis Toward Long-pulse Operation in a Fully-Tungsten Tokamak

Project: Research project

Project Details


The goal of this award is an integrated assessment of tungsten (W) as the primary plasma-facing material (PFM) in the long-pulsed tokamak, WEST, at CEA-Cadarache, France. The WEST (W Environment in Steady-state Tokamak) device's main mission is to test the ITER W divertor technology at scale. This testing is scheduled to begin as it enters its long-pulsed phase (Phase-2) in mid-2020. Phase-2 will have pulse lengths up to 1000 seconds and auxiliary heating power (PAUX) up to 15MW, including an expectation for routine high-confinement (H-mode) pulses of ~60 seconds and PAUX = 12MW. The US and WEST team will work together to characterize the tokamak performance in this all-W environment from the wall surface to the tokamak edge (including the H-mode pedestal) through both measurements and modeling.WEST's ITER-oriented, plasma-facing components (PFCs) mission and its long-pulse heritage from Tore Supra provide a unique opportunity that is unavailable within the US program to address a critical need of fusion energy development: PFC durability and compatibility with the tokamak plasma. Our proposal addresses these two major aspects of plasma-material interaction (PMI) science, as well as its practical application to steady-state fusion confinement. This focus gives three major research areas to the proposal:A. Toward informing PFC durability, we will attempt to further understand surface material properties (e.g. morphology) and their evolution due to PMI. The initial focus here is verification of the results of a multi-scale modeling effort by the US DOE PSI SciDAC team that is studying the near-surface effects of helium (a fusion by-product) bombardment on W PFCs;B. Addressing compatibility, we will attempt to quantify impurity generation and transport resulting from PMI at the whole device scale. We will build and apply a suite of synthetic diagnostics to use in interpretive modeling of experimental data so as to provide metrics by which the tokamak PFMs can be assessed in an overall way, i.e., from the wall to the confined tokamak plasma;C. Using this knowledge, we will attempt to control PMI effects on the main plasma performance. An innovative, dynamic wall conditioning technique of injecting low-Z powder during a WEST long-pulse discharge will be used to actively control the generation of PMI-induced impurities and thereby 'condition the wall surface.' Low-Z powder injection will also be used to attempt to actively control the tokamak edge transport barrier; overall discharge performance; and mitigate the effects of transients, such as ELMS.By integrating both aspects of PMI science with the control of impurity generation and transport, it is expected that the methodology developed and demonstrated in this project can then be used to help guide the design and development of solid-surface PFCs in future, steady-state fusion devices.
Effective start/end date9/1/238/31/25


  • Fusion Energy Sciences: $383,781.00


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