PSFC & D-IIID Collaboration
PSFC & D-IIID Collaboration
Magnetic Confinement

PSFC & D-IIID Collaboration

Six major areas of research: 1) RF Actuators for Fusion — Develop robust heating and current drive tools compatible with a fusion reactor environment. 2) Disruption Science — Advance disruption prediction, prevention and mitigation capabilities to enable the next generation of tokamaks. 3) Science of ELM-suppressed regimes — Develop high-performance ELM-suppressed regimes as viable candidates for next step devices through experiment and simulation. 4) Integrated studies of the tokamak core and edge — Advance integrated studies which couple core and edge physics, improving projections to burning plasma devices. 5) Transport physics and profile prediction — Leverage multi-scale, multi-channel transport physics and advanced computational techniques to predict tokamak profiles and develop burning plasma scenarios. 6) Material Assessment for Compact Fusion Power Plants and Plasma-Materials Interactions (PMI) — Perform novel characterization of plasma-material interactions (PMI) for a range of material choices.

Principal Investigator
Earl Marmar
Associate Director
and
Senior Research Scientist, Physics Department, Head of Magnetic Fusion Experiments
Team
Mirela Cengher
Mirela Cengher
Darin Ernst
Darin Ernst
Ivan Garcia
Ivan Garcia
Raul Gerru Miguela...
Raul Gerru Miguelanez
Malcolm Gould
Malcolm Gould
Robert Granetz
Robert Granetz
Nathan Howard
Nathan Howard
An older white woman with short white hair and frame-less glasses smiles broadly
Amanda Hubbard
Amanda Hubbard
Yijun Lin
Yijun Lin
Samuel Pierson
Samuel Pierson
Cristina Rea
Cristina Rea
A young a white man with dark coiffed hair and glasses gives a broad, friendly smile
Pablo Rodriguez-Fe...
Pablo Rodriguez-Fernandez
Jon Christian Rost
Jon Christian Rost
Alex Saperstein
Alex Saperstein
A middle-aged white man with thick glasses, a blue polo, and dark, short hair smiles mildly
Andrew Seltzman
Andrew Seltzman
A young Black man wearing a bright orange and purple patterned shirt looks serious
Arsene Stephane Te...
Arsene Stephane Tema Biwole
A young white man with tied back red hair and a mustache smiles broadly while corssing his arms
Roy Alexander (Ale...
Roy Alexander (Alex) Tinguely
Theresa Wilks
Theresa Wilks
Stephen J. Wukitch
Stephen J. Wukitch
Stuart Royce Sands...
Stuart Royce Sands Benjamin
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Amelia Cavallaro
Amelia Cavallaro
A young man with curly hair, mostly brown with a blonde highlight at the front. He wears a mercurial expression and has his head propped up on one hand
Jeremy Fleishhacke...
Jeremy Fleishhacker
Portrait photo
Zander Keith
Zander Keith
A young white man with short sandy hair smiles
Evan Leppink
Evan Leppink
A young white man with side-swept brown hair and wire-framed glasses and a black button up gives a huge smile
Andrew Maris
Andrew Maris
Grant Rutherford
Grant Rutherford
A young white man with dark curly hair gives a close-lipped smile
Benjamin Stein-Lub...
Benjamin Stein-Lubrano
Herbert Turner
Herbert Turner
Allen Wang
Allen Wang
Jinxiang Zhu
Jinxiang Zhu
An old man with deep wrinkles and white hair stares seriously at the camera
Miklos Porkolab
Miklos Porkolab
Jerry Hughes; A white man with graying hair smiles at the camera. He wears a light blue button up in front of a row of computers.
Jerry Hughes
Jerry Hughes
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Projects

1) MIT is contributing a major hardware enhancement to DIII-D which will drive off-axis current using a High Field Side (HFS) launched Lower Hybrid Current Drive (LHCD) System. Completion and first operation of the HFS-LHCD on DIII-D will occur in the first year of this proposal. Subsequent experiments using HFS-LHCD will allow us to assess the expected benefits of HFS launch on power coupling, validate our understanding of LH edge interactions, and evaluate current drive efficiency and profile control in a range
of discharges. MIT also collaborates on a project to study plasma boundary effects on radio frequency (RF) heating and current drive, centered on WEST.

2) We build on our leadership in disruption research to focus on several highlight topics. (1) Multi-machine disruption prediction, aided by Machine Learning (ML) methodologies, ultimately probes the existence of a universal disruption predictor capable of working on a new device based on existing tokamak data. (2) Pre-disruptive instabilities may be used to produce real-time estimates of metrics for proximity to a number of unstable operating scenarios, with special emphasis on tearing mode onset. (3) Efforts to quantify the
impact of high-Z plasma facing components on disruption likelihood and dynamics may be extended as metal plasma facing components (PFCs) are introduced into DIII-D. (4) Alternative disruption mitigation strategies require exploration for future devices, partly due to the potential formation of runaway electron beams, motivating MIT to collaborate on the science and technology enabling a passive runaway electron mitigation coil and on the exploration of massive gas detachment.

3) MIT has a long history of leadership in developing high confinement regimes with intrinsic suppression of edge localized modes (ELMs). Our team will explore the physics of I-mode by conducting further experiments on DIII-D, AUG and WEST, continuing to explore the turbulent edge transport in the regime, as well as the access window as determined by factors such as global operational parameters, edge radial electric field, application of 3D magnetic fields, and fueling. Detailed study of both core and pedestal turbulent transport will be undertaken in ELM-suppressed regimes. We will support this experimentally using MIT’s turbulence diagnostics at AUG, and through leading simulation and machine learning techniques. Domestically, we will lead in the FY22 US Joint Research Target activity on ELM-suppressed regimes, and in developing quiescent H-mode and Wide Pedestal Quiescent H-mode (QH, WPQH) regimes on DIII-D. We plan to conduct new experiments which will be supported by advanced analysis and simulations, including gyrokinetic simulations of both pedestal and core turbulence, continuing our leading validation efforts comparing to fluctuation measurements using advanced synthetic diagnostics. Also on DIII-D there are exciting prospects of probing the transport physics of negative triangularity discharges, which exhibit high global confinement without an H-mode edge.

4) MIT will advance the integration of core, pedestal and SOL transport models and accelerate experimental development of favorable burning plasma relevant scenarios, using the capabilities of the DIII-D facility. Existing DIII-D data and new experiments will be used to gather validation quality measurements of impurities from the core, pedestal, and the scrape off layer, utilizing unique capabilities such as MIT’s Laser Blow Off (LBO) system. We will use these data to validate an array of impurity transport models in the core/pedestal and edge/divertor regions, leading to a framework for wall-to-axis impurity density and radiation. MIT will continue innovation in measuring the fueling neutral species on DIII-D, to improve the characterization of neutral density and ionization profiles at multiple poloidal locations. This will move us further toward a comprehensive picture of edge particle transport, which will inform predictive capability of the density pedestal in high confinement regimes. Our diagnostic work will support scenario development for burning plasmas aimed at compatibility of a high-performance pedestal with desirable divertor heat flux management.

5) High fidelity core transport and profile prediction relies on computationally expensive gyrokinetic simulations. By applying optimization techniques, more efficient simulation of DIII-D target discharges will be obtained, which will in turn enable the use of advanced machine learning techniques to develop a profile prediction workflow that is accessible to the community and enables relatively tractable evaluation of steady-state plasma profiles based on nonlinear gyrokinetic simulation. In parallel, gyrokinetic model validation will be extended from the inner core plasma toward the top of the H-mode pedestal. Additional tools developed in house can contribute to scenario optimization and experimental planning on multiple devices, and to the understanding of multi-channel interactions in core turbulence and their effect on validation metrics (e.g. measurements of incremental thermal diffusivity) with integrated modeling and perturbative analysis. Prediction of full rotation velocity profiles is an important consideration, and a variety of models will be evaluated, from ongoing exercises in non-dimensional multi-machine scalings for intrinsic torque to full measurement and simulation of radial momentum transport coefficients. Innovative turbulence diagnostics such as soft x-ray imaging for large wavenumber electron temperature fluctuations will be explored.

6) Depth marker implantation has been utilized as a technique for studying erosion and redeposition of materials in tokamaks, and we propose to pursue the technique on DIII-D, studying materials such as SiC-based ceramics and tungsten coatings. Preparatory work to establish the net erosion diagnostic techniques on yet-to-be tested materials can begin at the DIONISIS facility at MIT, prior to deployment of marked materials on DIII-D. Exposures of materials on DIII-D will be complemented by installation of the Wall Interaction Tile Station (WITS) platform, and MIT collaboration on this hardware component is under discussion. Our PMI team also proposes to assess a novel in-situ, space- and time-resolved surface mapping diagnostic technique based on deploying an electron beam steerable to first wall PFCs in DIII-D and energy dispersive x-ray analysis to survey surface composition. This would introduce a powerful measurement capability for plasma-facing component (PFC) surfaces in magnetic confinement devices that will substantially advance the science of PMI, one of the key remaining technical challenges for magnetic fusion
energy.

Importance of Research

The MIT PSFC engages in the DIII-D program on multiple levels. Major facility upgrades like design and installation of an advanced current drive system and novel diagnostics are ongoing. Experimental science coupled with modeling and simulation are a central focus with scientists and students stationed onsite at DIII-D and on campus at MIT leading physics groups, conducting experiments, and contributing to the analysis ecosystem. Graduate students, postdoctoral researchers, and staff scientists participate at varying levels in research areas spanning advanced current drive techniques, disruption science and machine learning, pedestal and core-edge integration physics, plasma transport, and diagnostic development.

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Funding acknowledgement

The MIT PSFC engages in the DIII-D program on multiple levels. Major facility upgrades like design and installation of an advanced current drive system and novel diagnostics are ongoing. Experimental science coupled with modeling and simulation are a central focus with scientists and students stationed onsite at DIII-D and on campus at MIT leading physics groups, conducting experiments, and contributing to the analysis ecosystem. Graduate students, postdoctoral researchers, and staff scientists participate at varying levels in research areas spanning advanced current drive techniques, disruption science and machine learning, pedestal and core-edge integration physics, plasma transport, and diagnostic development.