PSFC Seminars

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

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

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

Theory Seminar: Instabilities and dissipation in collisionless magnetized turbulence

Lev Arzamasskiy

Princeton University

This talk will present the results from hybrid-kinetic particle-in-cell simulations of collisionless turbulence.

11:00am

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

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

Three-dimensional diagnostics for inertial confinement fusion research on OMEGA

Sean Regan

Laboratory for Laser Energetics

Progress in the diagnosis of low-mode multidimensional effects on hot-spot formation of OMEGA DT cryogenic implosions will be reported. 

3:00pm  |  NW17-218

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

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

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

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

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

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

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

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

Challenges and opportunities for transient control in high-field tokamaks

Carlos Paz-Soldan

General Atomics

The planned operating regime of the SPARC tokamak presents unique challenges and opportunities for transient control. This presentation will highlight expectations and extrapolations from the existing body of tokamak knowledge for the specific transient phenomena of 1) error field (EF) control, 2) edge-localized mode (ELM) control, and 3) runaway electron (RE) control. For EF control, the recently updated empirical scaling laws for EF penetration will be discussed, as well as opportunities for control afforded by ex-vessel trim coils. For ELM control, the expected ELM energy loss will be discussed as well as the prospects of 3D fields and quiescent H-mode operation to meet the ELM challenge. For RE control, expectations for RE formation and amplification will be discussed together with novel opportunities for RE control afforded at the design stage.

2:00pm  |  NW17-218

The science and programs of the High-Energy-Density Science Center at LLNL

Frank Graziani

Lawrence Livermore National Laboratory

Graziani discusses the strengths and weaknesses of the various computational approaches and briefly touches on two recent advances that may hold promise to enhancing the current weaknesses. The talk ends with a discussion of the High Energy Density Sciences Center, which is an outreach organization at LLNL that is building a HEDP community through interactions of LLNL scientists withacademic collaborators.
 

3:00pm  |  NW17-218

The effect of impurities on detachment, pedestal performance and global confinement

Livia Casali

General Atomics

Impurities in tokamaks, either originating from the wall or injected into the plasma with the aim of reducing power loads on divertor components, affect the pedestal and global confinement. As such, understanding the physics of such effects is vital for the operation of future devices.  At ASDEX Upgrade a reduction of the energy confinement has been observed with the introduction of the W metal wall attributed to the absence of a low-Z edge radiator. The confinement in AUG can be recovered with nitrogen seeding. The discussion of both AUG and DIII-D data aims to assess the impurity dynamics and their effects in high vs low Z wall machines.

3:00pm  |  NW17-218

Gyrokinetic analysis and simulation of pedestal transport

David Hatch

University of Texas, Austin

An understanding of pedestal transport is indispensable to tokamak design, optimization, and operation. This presentation will report on a broad range of gyrokinetic pedestal transport studies including the ongoing FY19 theory performance target (TPT), whose goal is to identify the turbulent transport mechanisms, along with the corresponding heat and particle sources, that govern pedestal dynamics.  

3:00pm  |  NW17-218

Testing predictions of electron scale pedestal turbulence in DIII-D H-modes

Walter Guttenfelder

Princeton Plasma Physics Laboratory

This talk will present experimental and gyrokinetic analysis of transport in the edge pedestal region of DIII-D ELMy H-mode discharges. The analysis is performed for two discharges with different divertor geometry to clarify the role of transport vs. sources in setting the pedestal density and temperature profiles.

3:00pm  |  NW17-218

Role of reconnection in magnetic plasma turbulence

Stanislav Boldyrev

University of Wisconsin-Madison

Numerical simulations, observations, and analytic models suggest that strong magnetic plasma turbulence forms anisotropic sheared magnetic structures that are not necessarily associated with energy dissipation, rather, they appear in a broad range of scales. We argue that given large enough Reynolds number of turbulence, such magnetic structures may become unstable to the tearing modes thus initiating processes of magnetic reconnection.

3:00pm  |  NW17-218

Pulsed power science and applications on Sandia's Z Machine

Daniel Brian Sinars

Sandia National Laboratories

This talk will highlight ongoing research on Z in magneto-inertial fusion, dynamic materials, and radiation science, as well as work being done by academic partners as part of our Z Fundamental Science Program.

2:00pm  |  NW17-218

Observable consequences of saturation by stable modes

Paul Terry

University of Wisconsin-Madison

This talk will examine the growing list of observable consequences of the saturation of ion temperature gradient turbulence by stable modes.  These include the wavenumber spectrum of ITG turbulence, the scaling of its turbulence level with zonal flow damping rate, and the rate of heat flux decrease with beta in gyrokinetic simulations.

3:00pm  |  NW17-218

Special Seminar: A Laboratory Model for Magnetized Stellar Winds

Ethan Peterson

University of Wisconsin-Madison

4:30pm  |  NW17-218

Fusion and laser plasma research interaction at LLE: status and future

Mike Campbell

Laboratory for Laser Energetics

A novel experimental platform, advanced diagnostics and simulation tools have been established at LLE and an advanced laser concept that has the potential to expand laser parameter space for all laser fusion approaches is under development. In addition to expand the opportunities for high energy density science, a new facility that includes two 30 Petawatt lasers has recently been proposed and will also be presented. 

3:00pm  |  NW17-218