PSFC Seminars

Seminars are currently being held as hybrid events. 
For further information & zoom link: info@psfc.mit.edu
PSFC address: NW17-218, 175 Albany Street, Cambridge

Nov 23, 2020

Large-moment simulations of plasma dynamics with exact conservation

Federico Halpern

General Atomics

We discuss a new approach to plasma fluid simulations that leads to fast, simple, and reliable codes. This can be achieved by using the anti-symmetric representation of the fluid models, which exposes the underlying conservation laws in a way that is directly translatable to computers. The method is completely generic -- we show examples of its application in MHD and turbulence simulations in large modern clusters. Zoom link:  https://mit-psfc.zoom.us/j/6174522043?pwd=NHN3ZHFURUJLM0VkQnprOVkyaVhNUT09

2:00pm  |  Remote

Nov 18, 2020

Pellet actuator development at AUG in view of DEMO

Peter Lang

Max Planck Institute for Plasma Physics

Operation in a future fusion reactor will aim to establish a high plasma core density in order to harvest a maximum output power.  This requires an efficient core fuelling actuator, capable to establish the required target value with a minimum of applied particle flux. For the development of a potentially multi-tasking pellet launching system appropriate for reactor requirements, we have chosen a step-by-step approach along the route ASDEX Upgrade, JT-60SA and EU-DEMO. The AUG pellet system is operating since almost 30 years, meanwhile optimised for high-speed inboard launch. Currently, a novel and state-of-the art pellet system is being built for the new large superconducting tokamak JT-60SA. Finally, a conceptual design for EU-DEMO’s core fuelling actuator is under way. Ongoing design optimisation takes care of keeping the fuel inventory as low as reasonably achievable while staying compatible with the EU-DEMO design. Join Zoom Meeting
https://mit-psfc.zoom.us/j/6174522043?pwd=NHN3ZHFURUJLM0VkQnprOVkyaVhNUT09

11:00am  |  Remote

Oct 28, 2020

Indications of turbulence-optimized operation scenarios for Wendelstein 7-X

Adrian von Stechow

Max Planck Institute for Plasma Physics

This talk focuses on results from various turbulence diagnostics from the plasma core to the scrape-off layer, and showcases high-performance scenarios which imply that a certain degree of turbulence control is possible by tailoring the driving kinetic profile gradients. These findings are supported by gyrokinetic simulations which show that W7-X benefits from improved resilience against trapped electron modes through its quasi-isodynamic symmetry property.   Join Zoom meeting: https://mit-psfc.zoom.us/j/6174522043?pwd=NHN3ZHFURUJLM0VkQnprOVkyaVhNUT09  

11:00am  |  Remote

Oct 27, 2020

JT60-SA construction and research strategy

Yutaka Kamada

National Institutes for Quantum and Radiological Science and Technology (QST)

Construction of JT-60SA tokamak was completed in March 2020 and the integrated commissioning is now underway.  Manufacture and assembly of all the main tokamak components have been successfully completed satisfying technical requirements including functional performances and dimensional accuracies. Development of plasma actuators and diagnostics is also going well such as achievement of long sustainment of high energy intense negative ion beam. Commissioning of the power supply and the cryoplant has also satisfied requirements. Development of all the control systems and evaluation procedures of tokamak operation has been completed. These experiences of assembly, integrated commissioning and plasma operation of JT-60SA contribute to ITER risk mitigation and efficient implementation of ITER operation.  Join Zoom Meeting   https://mit-psfc.zoom.us/j/6174522043?pwd=NHN3ZHFURUJLM0VkQnprOVkyaVhNUT09

10:00am  |  Remote

Oct 19, 2020

A systems and control perspective on fusion plasmas

Marco de Baar

Dutch Institute for Fundamental Energy Research (DIFFER)

The control parameters and associated processes for a fusion reactor are identified and classified in seven control categories. Basic control concepts are introduced. A short historical overview is given of the developments in modern systems and control theory and control engineering. The state-of-the-art of the field of fusion plasma control for the 7 categories. Special emphasis will be put on those developments that are relevant for Nuclear Fusion research in general and - if time allows - for the SPARC programme in particular.  Join Zoom Meeting
https://mit-psfc.zoom.us/j/6174522043?pwd=NHN3ZHFURUJLM0VkQnprOVkyaVhNUT09  

10:00am  |  Remote

Oct 16, 2020

ARC and the path to high field fusion

Brandon Sorbom

Commonwealth Fusion Systems

Since the publication of the original papers, there has been a large amount of development into both the physics and technology underlying compact, high-field tokamaks, as evidenced in numerous recent SPARC publications and hardware development being carried out by MIT and CFS. This work in both physics and technology has provided a clearer picture of the feasibility of different development pathways to an ARC-like power plant and will be presented in this talk.  Join Zoom Meeting
https://mit-psfc.zoom.us/j/6174522043?pwd=NHN3ZHFURUJLM0VkQnprOVkyaVhNUT09  

3:00pm  |  Remote

Oct 5, 2020

Modeling SOL thermal transport in high power tokamaks; the ARC divertor and ITER non-local transport

Mike Wigram

Plasma Science and Fusion Center

This talk will present the results of Wigram's PhD thesis work, which tackled two topics within this wide research area: assessing the performance of advanced divertor geometries in the ARC reactor concept, and studying the impact of `nonlocal' thermal transport on modelling predictions for the ITER tokamak SOL.  Join Zoom Meeting: https://mit-psfc.zoom.us/j/6174522043?pwd=NHN3ZHFURUJLM0VkQnprOVkyaVhNUT09

2:00pm  |  Remote

Mar 13, 2020

Active spectroscopy measurements of the Deuterium temperature, rotation, and density in the pedestal region of the DIII-D tokamak

Shaun Haskey

Princeton Plasma Physics Laboratory

Main-ion charge exchange recombination spectroscopy (MICER) [1,2] uses the neutral beam induced D-alpha emission spectrum to determine the local deuterium ion (D+) temperature, rotation and density, as well as several beam and equilibrium properties from the neutral beam emission. The measurements and analysis demonstrate the state of the art in active spectroscopy and integrated modeling for diagnosing fusion plasmas and the importance, despite the difficulties, of direct D+ measurements at the plasma edge.

3:00pm  |  NW17-218

Mar 6, 2020

The physics of SPARC: a high-field, burning plasma tokamak

Alex Creely

Commonwealth Fusion Systems

This talk introduces the SPARC device, describes the basis for the present performance projections, and summarizes some of the physics modeling work that are currently in progress.

3:00pm  |  NW17-218

Mar 5, 2020

Theory Seminar: The failure of the Chapman-Enskog expansion in a collisional plasma

Archie Bott

Princeton University

This talk discusses the kinetic stability of classical, collisional plasmas. Fluid equations are typically used to describe such plasmas, since their distribution functions are close to being Maxwellian. The small deviations from the Maxwellian distribution are calculated via the Chapman-Enskog (CE) expansion, and determine macroscopic momentum and heat fluxes in the plasma.

3:00pm  |  NW17-218

Feb 21, 2020

Tokamak plasma edge studies by microwave short-pulse reflectometry and backscattering in TCV

Pedro Cabrera

MIT Plasma Science and Fusion Center

This talk will discuss two new diagnostics developed at the TCV tokamak: a Doppler backscattering (DBS) system and short-pulse reflectometer (SPR). Innovative experiments with the DBS diagnostic have demonstrated a new approach to generating and detecting multiple simultaneous frequencies using a digital AWG and direct sampling. Furthermore, the magnetic-field line pitch angle at the edge has been estimated by rotating the polarisation axis orientation of the probing beam while maintaining a constant ellipticity.

3:00pm  |  NW17-218

Feb 13, 2020

Theory Seminar: Magnetic reconnection and plasmoid formation in black hole accretion flows

Bart Ripperda

Princeton University/Flatiron Institute

In this talk I will show general relativistic resistive magnetohydrodynamics models of magnetic reconnection and associated plasmoid formation in a wide range of accretion flows. I will show that plasmoids are a ubiquitous feature of accretion flows regardless of the magnetic field geometry and the spin of the black hole.

10:30am  |  NW17-218

Feb 7, 2020

Localized divertor leakage measurements using isotopic tungsten sources and implications on core contamination during ELM-y H-mode discharges on DIII-D

Zeke Unterberg

Oak Ridge National Laboratory

Experiments carried out on DIII-D using isotopic tungsten (W) sources in the outer divertor have characterized how the W leakage from this region depends on both the exact source location and edge-localized mode (ELM) behavior. These studies help to elucidate the physics driving divertor impurity source rates and leakage, with and without ELMs, and provide better insight on the link in the chain connecting wall impurity sources to core impurity levels in magnetic fusion devices.

3:00pm  |  NW17-218

Dec 13, 2019

Tritium extraction from gases, liquid metals, and molten salts

Paul Humrickhouse

Idaho National Laboratory

This presentation will review extraction system concepts presently envisaged for use with solid ceramic, liquid lead-lithium, and molten salt blankets, and the underlying transport phenomena they exploit, and will give an overview of corresponding R&D efforts occurring worldwide, with a particular focus on membrane-based systems and related experiments presently under development at Idaho National Laboratory.

3:00pm  |  NW17-218

Dec 6, 2019

Optimized Stellarators for Fusion Pilot Plants

Aaron Bader

University of Wisconsin-Madison

This talk will focus on how stellarators are optimized, both for the current optimized experiments that exist today, and for future experiments, pilot plants, and reactor concepts.  Six topical areas, identified as key physics gaps for stellarators, are discussed: turbulent transport optimization by design, energetic particle transport, divertor performance, impurity transport, MHD stability, and coil design. The talk will conclude with a perspective for a stellarator pilot plant in both a high-risk short-term scenario and a lower-risk, longer-term scenario.

3:00pm  |  NW17-218

Nov 8, 2019

Magnetic reconnection and plasma turbulence: key discoveries with MMS

R.B. Torbert, K.J. Genetreti, M.R. Argall

University of New Hampshire and Southwest Research Institute

First part: Overview of MMS Mission and Insights into Symmetric Reconnection in the Earth’s Magnetotail. (Torbert)
Second part: MMS insights into asymmetric reconnection at the Earth’s magnetopause   (Genestreti)
Third part: MMS and turbulence throughout the magnetosphere, magnetosheath, and solar wind   (Argall)
 

3:00pm  |  NW17-218

Oct 4, 2019

Developing the physics basis for power exhaust solutions for a compact pilot plant

John Canik

Oak Ridge National Laboratory

Predictions for the scrape-off layer (SOL) in future fusion devices based on empirical scalings imply extremely large parallel heat flux, q|| ~10 GW/m2, which is exacerbated for high-field concepts that may enable a Compact Pilot Plant (CPP) as recommended by a recent US strategic planning assessment. Here we discuss the framework of a program to more firmly establish the basis for power handling in tokamaks by extending the paradigm of solid (likely high-Z) walls using noble gas seeding to increase impurity radiation. 

3:00pm  |  NW17-218

Oct 2, 2019

Special Seminar: GaToroid: A novel superconducting compact and lightweight gantry for hadron therapy

Enrico Felcini

CERN

GaToroid is new a concept of beam delivery system for hadron therapy, based on a steady-state, axis-symmetric field configuration. The basic idea is to use fixed toroidal magnets, producing the axis-symmetric field that bends beams from several directions into patient. The magnetic field of this toroidal gantry is static and neither the magnets nor the patient need to be rotated.

3:00pm  |  NW17-218

Sep 27, 2019

3D-printed fusion devices: Towards high-field ignition stellarators

Vicente Queral

CIEMAT

This talk will present additive and innovative manufacturing methods for toroidal fusion devices of the stellarator type, and a high-field ignition stellarator concept (i-ASTER). The coils and vacuum vessel of stellarators are geometrically complex. To deal with this complexity, additive manufacturing combined with composites appears appropriate. This technique is investigated and implemented in a table-top stellarator (UST_2), and is planned for i-ASTER. 

3:00pm  |  NW17-218

Sep 25, 2019

Theory Seminar: A deep dive into the distribution function: understanding phase space dynamics using continuum Vlasov-Maxwell simulations

James Juno

University of Maryland, College Park

This talk will focus on the competition of small scale kinetic instabilities driven by unstable beams of plasma, and present a set of results where the generation of small scale structure in velocity space affects the overall macroscopic evolution of the plasma. It will also address the computational challenges in developing a continuum Vlasov-Maxwell code, and motivate my efforts to develop this code by demonstrating how particle noise modifies the dynamics of the same set of simulations.

3:00pm  |  NW17-218

Sep 20, 2019

Pellet injection and record performance in the W7-X stellarator

Per Helander

Max Planck Institute for Plasma Physics

In most stellarators, the neoclassical energy losses are very large, and for this reason the magnetic field in Wendelstein 7-X was optimised to reduce such losses. As a result, the experimentally observed transport is mostly turbulent, but in certain plasmas fueled by cryogenic pellets the net energy transport is comparable to the neoclassical prediction. These plasmas offer an opportunity to experimentally verify the efficacy of the optimisation. By comparing with other stellarators, it is possible to conclude that the confinement in W7-X exceeds that achievable in other magnetic configurations, even if the turbulence is completely suppressed. 

3:00pm  |  NW17-218

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