PSFC Seminars

From SOL turbulence to planetary magnetospheres: computational plasma physics at (almost) all scales using the Gkeyll code

Ammar Hakim

Princeton Plasma Physics Laboratory

In this talk I will present algorithmic innovations and physics simulated by the Gkeyll code. In particular, I will focus on recent progress in implementing a  novel algorithm for EM gyrokinetics in the symplectic formulation; and progress in developing a robust semi-implicit algorithm for multi-fluid moment equations. Physics of turbulence in NSTX SOL will be presented, in particular, the statistics of blobs and heat-flux on divertor plates.

3:00pm  |  NW17-218

H-mode grade confinement with L-mode edge in negative triangularity plasmas on DIII-D

Alessandro Marinoni

MIT

3:00pm  |  NW17-218

Measurement of RF electric fields relevant for heating and current drive

Elijah Martin

Oak Ridge National Laboratory

In this seminar, the diagnostic and associated experimental results obtained from an RF sheath test stand (IC), Tore Supra (LH) and Alcator C-Mod (LH) will be presented.  Future diagnostic plans for the RF sheath test stand (IC), WEST (LH) and DIII-D (LH and EC) will be discussed.

3:00pm  |  NW17-218

Real-time wall conditioning through low-Z dust injection in ASDEX-Upgrade and DIII-D plasmas

Alessandro Bortolon

Princeton Plasma Physics Laboratory

The seminar will introduce recent experiments carried out in DIII-D and ASDEX-Upgrade tokamaks, exploring the possibility of generating boron coatings in “real-time”, by injection of boron and boron enriched powders during tokamak operation.

11:00am  |  NW17-218

High-field tokamaks: From Alcator to ARC

Bob Mumgaard

Commonwealth Fusion Systems

The seminar will trace the history of the high-field approach from its inception to its hiatus and its revival via HTS superconductors. We'll examine the various limitations of high-field copper and HTS magnets and the characteristics of high-field tokamaks as a class evolving from the invention of tokamaks to today.  Then we'll look forward to explore the high-field tokamak power plants based on the ARC-concept as a class.  We'll compare and contrast the attributes of these ARC-like power plants with their ITER-like or ARIES-like counterparts. 

3:00pm

Building an open source Python software ecosystem for plasma physics

Nick Murphy

Harvard-Smithsonian Center for Astrophysics

In this talk, Nick Murphy will describe modern best practices for scientific computing that we are adopting in PlasmaPy [2], present PlasmaPy’s current and planned capabilities, and discuss how our community can work together to forge an open source software ecosystem in coming years.

3:00pm  |  NW17-218

Supporting stockpile stewardship with high-energy-density physics experiments

Alan Wan

Lawrence Livermore National Laboratory

This presentation summarizes the range of High-Energy-Density (HED) physics experiments that deliver data meeting the mission requirements for stockpile-stewardship-relevant physics issues in regime otherwise inaccessible with other facilities.  Key HED physics topics range from material properties at high-pressure and temperatures, to radiation transport and radiation hydrodynamics.

11:00am  |  NW17-218

CRF physics studies using the Large Plasma Device

Troy Carter

UCLA

An experimental campaign on the physics of ICRF waves has recently begun using the Large Plasma Device (LAPD) at UCLA. A new high-power (∼150 kW) RF system and antenna have been developed for excitation of large amplitude fast waves in LAPD. The source runs at a frequency of 1-5 MHz, corresponding to ∼1-10 f_ci, depending on plasma parameters. Recent work has focused on the structure and scaling of RF sheaths and convection cells near the antenna.

3:00pm  |  NW17-218

Collisionless plasma shocks: properties, interests and similarities to fluid shocks

Antoine Bret

Universidad de Castilla-La Mancha

A neutral fluid can sustain shockwaves where dissipation at the shock front is provided by binary collisions. In a plasma, collective effects can equally provide dissipation so that shockwaves can develop over length scales much shorter than the mean free path. Such shocks have been dubbed “collisionless shock”. After reviewing the mechanism of their formation, we will explain why they have been attracting so much attention in recent years. Finally, we will comment on the similarities and differences their offer with respect to fluid shocks.

3:00pm  |  NW17-218

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