PSFC Seminars

All Seminars are on Friday at 3pm, unless otherwise noted.
NW17-218, 175 Albany Street, Cambridge
For further information: info@psfc.mit.edu

Past Events

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

Aug 29, 2019

Robinson Research Institute's (RRI) journey into commercial applications of HTS

Rod Badcock

Robinson Research Institute

Rod Badcock will show the journey of Robinson Research Institute into commercial application of HTS, and show in more detail some of the highlights of the New Zealand programme. Finally he will explore current work into an interesting class of all HTS magnet power supplies, called HTS dynamos, that have the potential to deliver 1000's of amps without imposing large cryogenic loads.

3:30pm  |  NW17-218

Jul 19, 2019

Practical strategy toward fusion DEMO with some lessons from ITER and LHD projects

Arata Nishimura

National Institute of Science, Japan; Technical Institute of Physics and Chemistry, Chinese Academy of Sciences

Since the fusion reactor will emit a lot of high energy neutrons, all devices and components in the building will be irradiated and activated, also the building itself. In addition, the secondary activation must be considered. Most of the large-scale plasma devices have been operated only for non D-T plasma so the radiation measures have not been necessary. When the device is designed with an idea of the D-T reaction, the construction site has to be satisfied several conditions and special facilities must be equipped. In this talk, such consideration on the construction site conditions will be introduced first. The nitrogen isotopes of 16N and 17N will be introduced as a practical example of the secondary activation.

10:30am  |  NW17-218

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