PSFC Seminars

Plasma-facing components in next-step fusion devices: Implications from fuel retention and thermomechanical material property studies

George Tynan

University of California San Diego

In this talk we examine critical aspects of tungsten as a first wall material in nuclear-grade fusion devices.

3:00pm  |  NW17-218

Special Seminar: Edge Pedestal Characteristics of Quiescent H-mode Plasmas in DIII-D

Theresa Wilks

MIT

This talk will focus on the differences between the standard QH-mode and one with a high and wide pedestal, which is often associated with enhanced confinement and unique edge pedestal turbulence characteristics, as well as the recent advances of the wide pedestal QH-mode towards ITER-like conditions.

11:00am  |  NW17-218

Special Seminar: Evidence for turbulent-generated parallel sheared intrinsic flow in a linear plasma device

G. R. Tynan

University of California San Diego

In this work, we present results from a cylindrical helicon plasma device that show evidence for turbulence-generated parallel flows.

2:00pm  |  NW17-218

Tour of Resynthesizer and C-Mod

Hear Alcator C-Mod data become a mysterious soundscape on a tour of the resynthesizer and Alcator C-Mod. Learn more and register here.

May 9, 16, 23, 30, June 6  |  NW21

Unusual effects in rotating plasma

Nat Fisch

Princeton University

Rotating plasma can exhibit certain unusual effects, both in providing confinement and in affecting particle transport. These effects can be exploited in a variety of plasma devices, including Hall thrusters, plasma mass filters, and fusion confinement devices.  In pulsed devices, rotating plasma can exhibit unusual heat capacity effects.  A promising but highly speculative possibility is to exploit rotation to achieve magnetic confinement in a plasma torus, replacing in part the toroidal electron current.

3:00pm  |  NW17-218

Multi-scale turbulence in the core of tokamak plasmas

Nathan Howard

MIT

This talk will present an overview of recent multi-scale gyrokinetic simulations of Alcator C-Mod L and H-mode discharges and will discuss the status of multi-scale investigations from around the world.

3:00pm  |  NW17-218

New insights on scrape-off layer plasma turbulence

Paolo Ricci

École Polytechnique Fédérale de Lausanne

With the goal of improving our understanding of plasma turbulence in the SOL, the GBS code has been developed in Lausanne during the past few years. Prof. Ricci will present simulation and theoretical results, and compare them with experimental measurements from several tokamaks worldwide.

3:00pm  |  NW17-218

Parametric instability, inverse cascade, and the 1/f range of solar-wind turbulence

Ben Chandran

University of New Hampshire

In this talk, Prof. Chandran will describe a weak-turbulence calculation of the nonlinear evolution of the parametric instability in the solar wind at wavelengths much greater than the ion inertial length under the assumption that slow waves, once generated, are rapidly damped.  He will show that the parametric instability leads to an inverse cascade of Alfven-wave quanta and present several exact solutions to the wave kinetic equations. 

3:00pm  |  NW17-218

Special Seminar: Advances and discoveries en route to magnetically confined pair plasmas

Eve Stenson

Technische Universität München

The goal of the APEX (A Positron Electron eXperiment) collaboration is to create and study pair plasmas confined in the magnetic field of a levitated dipole.  This talk will describe how significant milestones to date --- as well as ongoing and upcoming activities --- move the project closer to pair plasma creation.

11:00am  |  NW17-218

Discontinuous Galerkin methods, positivity, exponential reconstruction, and initial simulations of gyrokinetic turbulence in a model tokamak scrape-off-layer

Greg Hammett

Princeton Plasma Physics Laboratory

We describe the development of the Gkeyll code to carry out 3d2v full-F gyrokinetic simulations of plasma turbulence in open-field-line geometries, using special versions of discontinuous-Galerkin (DG) algorithms to help with the computational challenges of the edge region. (Higher-order algorithms can also be helpful for exascale computing, because they reduce the ratio of communications to computations.)  We describe methods for handling positivity constraints, involving exponential reconstructions while preserving conservation properties of the underlying Hamiltonian system.  

3:00pm  |  NW17-218

Recent advances in measuring and understanding plasma rotation in the DIII-D tokamak

Brian Grierson

Princeton Plasma Physics Laboratory

Recent advances in high temperature plasma diagnostics have enabled the first routine, direct measurement of the flow of the fuel ions in the DIII-D tokamak, and researchers have used these measurements to characterize the plasma rotation and compare with simulations.  In this presentation, Brian Grierson will describe the measurement technique for determining the ion flow and intrinsic rotation phenomenology in the tokamak core, and also near the plasma boundary.

3:00pm  |  NW17-218

Particle transport from the bottom up

Saskia Mordijck

College of William and Mary

Fusion gain is directly linked to the density of the plasma fuel. However, due to the high temperatures, it impossible to fuel the core of the plasma directly. In this talk, Prof. Mordijk will elucidate how particle transport changes from the core to the plasma edge as a result of changes in turbulence characteristics.

3:00pm  |  NW17-218

The role of anisotropy-driven plasma instabilities in electron heating and acceleration at galaxy cluster shocks

Lorenzo Sironi

Columbia University

The bright radio emission from shocks in galaxy clusters requires efficient electron acceleration to non-thermal energies, but the acceleration mechanism remains poorly understood.

3:00pm  |  NW17-218

New advancements in high field superconducting magnet and cryogenic technologies and applications

Ziad Melhem

Oxford Instruments

Recent advances in low temperature superconductors (LTS) and high temperature superconductors (HTS) and Cryofree^® technology have opened up a new era in superconducting magnet development for a variety of applications including condensed matter research, materials research, nanotechnology and many other applications.

2:00pm  |  NW17-218

News from the world of stellarators: W7-X results and theoretical insights

Per Helander

Max Planck Institute for Plasma Physics

3:00pm  |  NW17-218

Effect of velocity-space anisotropy on waves, turbulence, and transport in high-beta astrophysical plasmas

Matthew Kunz

Princeton University

In this talk, the speaker will present hybrid-kinetic simulations of waves, turbulence, and magnetorotationally driven transport in collisionless, high-beta plasmas, which address how Larmor-scale kinetic instabilities are driven by and ultimately regulate temperature anisotropy, and how this regulation in turn feeds back on the macroscale dynamics.

3:00pm  |  NW17-218

The Advanced Tokamak Path to a compact fusion pilot plant

Richard Buttery

General Atomics

Studies show that well targeted research in the coming years could validate these concepts to provide the basis to proceed with a compact Advanced Tokamak power plant. This talk will set out the key physics and hardware considerations behind its design.

3:00pm  |  NW17-218

Electrochemistry in the molten state: from sustainable metal extraction to materials fundamentals

Antoine Allanore

MIT Department of Materials Science and Engineering

This seminar offers to report electrochemical studies of a subset of molten oxide and sulfide systems. Our results show that the molten state offers unique functionalities (enhanced mass transport, high conductivity, electronic conductivity, thermoelectric power) and that electrochemistry is uniquely positioned to probe the structure and physical chemistry of those systems. In addition, our results provide valuable thermodynamic information, and our experimental developments suggest a faster path to experimental data, along with an improvement in the prediction and modeling capacity of the molten state.

3:00pm  |  NW17-218

First results from divertor operation in the Wendelstein 7-X stellarator

Thomas Sunn Pedersen

Max Planck Institute for Plasma Physics

This talk will introduce the Wendelstein 7-X (W7-X) stellarator, a highly optimized stellarator experiment that went into operation in 2015. With a 30 cubic meter volume, a superconducting coil system operating at 2.5 T, and steady-state heating capability of eventually up to 10 MW, it was built to demonstrate the benefits of optimized stellarators at parameters approaching those of a fusion power plant. 

3:00pm  |  NW17-218

Alfvén eigenmode studies on JET

Valentin Aslanyan

MIT

Experiments to probe AEs with a resonant magnetic field have been undertaken on JET for 20 years. An upgrade to the AE active diagnostic (AEAD) antennas has recently been completed with the aim of measuring the modes' damping rates in upcoming DT experiments. The frequency range of the diagnostic has been extended downwards allowing detection of Beta (Acoustic) AEs and Geodesic Acoustic Modes, whose understanding is increasingly seen as important to future machines.

11:00am  |  NW17-

Taming the plasma-material interface in plasma-burning nuclear fusion reactors

Jean Paul Allain

University of Illinois at Urbana-Champaign

This talk will focus on outlining both the challenges and promises of PMI research in nuclear fusion today and the prospects for possible solutions for future plasma-burning fusion reactors.  The talk will in part summarize the recent DOE Fusion Energy Sciences Workshop on Plasma-Material Interactions and also highlight some of the recent work in Prof. Allain’s RSSEL group at UIUC.

3:00pm  |  NW17-218

The influence of the SOL on pedestal performance in ASDEX Upgrade

Michael Dunne

Max Planck Institute for Plasma Physics

This seminar will introduce some of the possible mechanisms for SOL-pedestal interactions and show experimental and modelling results from ASDEX Upgrade focusing on this area.

3:00pm  |  NW17-218

The impact of divertor conditions on SOL density profile at the JET tokamak

Bruce Lipschultz

York University

The low temperature boundary layer plasma (Scrape-Off-Layer or SOL) between the hot core and the surrounding vessel determines the level of power loading and erosion and implantation of material surfaces, and thus the viability of tokamak-based fusion as an energy source. This study using the JET tokamak explores several mechanisms affecting the formation of flattened density profiles, the so-called density shoulders, in the low-field side (LFS) SOL.

3:00pm  |  NW17-281

Gyrokinetic studies on multi-scale drift wave turbulence and zonal flows in toroidal plasma

Tomo-Hiko Watanabe

Nagoya University

Cross-scale interactions among turbulence and zonal flows involving multiple spatiotemporal scales have emerged as a key issue in transport studies of fusion plasma. In this talk, we would like to discuss three topics of homogeneous gyrokinetic turbulence simulations which have been carried out by use of peta-scale computers.

3:00pm  |  NW17-218

Spontaneous, superradiant and stimulated interactions of free electrons with light

Avraham Gover

Tel Aviv University

Prof. Gover will review the variety of free electron radiation devices and electron-radiation interaction schemes, and present both classical and quantum theoretical basis for their analysis.

3:00pm  |  NW17-218