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

Mar 11, 2021

Multiple isotope pellet cycles captured by turbulent transport modelling in the JET tokamak

Michele Marin

DIFFER

Accurate modelling of particle transport is crucial to interpret and predict tokamak experiments. In this talk, we will address how multi-ion integrated modelling was utilized to reproduce recent experimental observations. Specically, fast mixing of the isotopes in Ion Temperature Gradient dominated turbulent regime in both gas pu and pellet fuelled discharges will be discussed in details. The results have implications for multi-isotope core fuelling and burn control.

10:00am  |  Virtual

Mar 3, 2021

Exploring the most extreme conditions of matter with ultra-bright X-rays

Siegried Glenzer

SLAC National Accelerator Laboratory

At SLAC, we are now studying extreme states of matter in the laboratory. We apply enormous pressures to earthbound samples and use our X-ray laser, the Linac Coherent Light Source, to take split-second photographs of the states that result. This lecture will describe these experiments. The information we are gathering provides fundamental insights into the physical properties of matter in extreme conditions whose understanding is important for modeling astrophysical processes and for pursuing controlled fusion.  

1:00pm  |  Virtual

Feb 25, 2021

The increasing peril from nuclear arms: and how physicists can help reduce the threat

Stewart Prager

Princeton University

With geopolitical and technological changes mostly driven by the nuclear weapons states, we are slipping towards a new arms race and deterioration of the multi-decade arms control regime. This talk will describe the current critical situation, feasible steps to reduce the nuclear threat, and a new project sponsored by the American Physical Society to engage physical scientists in advocacy for nuclear threat reduction.

3:00pm  |  Virtual

Feb 19, 2021

Integrated modeling of tokamak plasma confinement combining core and edge pedestal physics

Teobaldo Luda

Institute for Plasma Physics

The design of future fusion reactors and their operational scenarios requires an accurate prediction of the plasma confinement. We have developed a new model that integrates different elements describing the main physics phenomena which determine plasma confinement. In particular, we are coupling a new pedestal transport model, based on empirical observations, to the ASTRA transport code, which, together with the TGLF turbulent transport model and the NCLASS neoclassical transport model, allows us to describe transport from the magnetic axis to the separatrix.

10:00am  |  Virtual

Feb 11, 2021

PUFFIN: a new microsecond pulser for magnetized high energy density plasma experiments at MIT

Jack Hare

MIT

In this talk Jack Hare will discuss PUFFIN (puffin.mit.edu), a new pulsed-power facility that will start construction at MIT in 2021. PUFFIN's unique capability is a microsecond drive time, much longer than existing pulsed-power facilities, which are optimised for driving implosions in around 100 ns. These long drive times open up the new frontiers in high-energy-density laboratory astrophysics, enabling us to study the steady-state behaviour of magnetized turbulence or the growth of instabilities such as plasmoids in magnetic reconnection.
 

10:00am  |  Virtual

Feb 4, 2021

Studies on the impact of particle sources on turbulence and transport at AUG, fueling pellets and cold pulses by impurity laser ablation

Clemente Angioni

Institute for Plasma Physics

Two interesting cases of the impact of specific particle sources on the turbulence and transport  in tokamak plasmas are considered with a combination of experiments at ASDEX Upgrade and of dedicated simulations with gyrokinetic and gyrofluid models and linked by the transient development of hollow density profiles.

10:00am  |  Virtual

Dec 11, 2020

Exploring synergy between two frequencies of lower hybrid power on EAST

Wilkie Choi

Princeton Plasma Physics Laboratory

To investigate the optimal conditions for LH synergy, a recent experiment scanned the power fraction from the two antennas while maintaining constant total injected power, for two different density conditions. Zoom link:     

3:30pm  |  Remote

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

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