A5075611243- Magnetic confinement fusion research
- Ionosphere and magnetosphere dynamics
- Particle accelerators and beam dynamics
- Solar and Space Plasma Dynamics
- Superconducting Materials and Applications
- Fusion materials and technologies
- Plasma Diagnostics and Applications
- Laser-induced spectroscopy and plasma
- Astro and Planetary Science
- Laser-Plasma Interactions and Diagnostics
- Geophysics and Gravity Measurements
- Computational Physics and Python Applications
- Machine Learning and ELM
- Atomic and Subatomic Physics Research
- Spacecraft and Cryogenic Technologies
- Gamma-ray bursts and supernovae
- Electromagnetic Launch and Propulsion Technology
- Magnetic properties of thin films
- Firm Innovation and Growth
- Nuclear Materials and Properties
- Heat Transfer and Optimization
- Distributed and Parallel Computing Systems
- Metallic Glasses and Amorphous Alloys
- Additive Manufacturing Materials and Processes
- Muon and positron interactions and applications
Princeton Plasma Physics Laboratory
2021-2024
University of Wisconsin–Madison
2016-2024
General Atomics (United States)
2024
Princeton University
2021
Abstract WEST is an MA class superconducting, actively cooled, full tungsten (W) tokamak, designed to operate in long pulses up 1000 s. In support of ITER operation and DEMO conceptual activities, key missions are: (i) qualification high heat flux plasma-facing components integrating both technological physics aspects relevant particle exhaust conditions, particularly for the monoblocks foreseen divertor; (ii) integrated steady-state at confinement, with a focus on power issues. During phase...
Abstract Using a recently installed impurity powder dropper (IPD), boron (<150 μ m) was injected into lower single null (LSN) L-mode discharges in WEST. IPDs possibly enable real-time wall conditioning of the plasma-facing components and may help to facilitate H-mode access full-tungsten environment The this experiment featured I p = 0.5 MA, B T 3.7 T, q 95 4.3, t pulse 12–30 s, n e,0 ∼ 4 × 10 19 m −2 , P LHCD 4.5 MW. Estimates deuterium particle fluxes, derived from combination visible...
Abstract The pre-thermal quench (pre-TQ) dynamics of a pure deuterium ( <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:mrow> <mml:msub> <mml:mi mathvariant="normal">D</mml:mi> </mml:mrow> <mml:mn>2</mml:mn> </mml:msub> </mml:math> ) shattered pellet injection (SPI) into <mml:mn>3</mml:mn> <mml:mstyle scriptlevel="0"/> <mml:mi>MA</mml:mi> / <mml:mn>7</mml:mn> <mml:mi>MJ</mml:mi> JET H-mode plasma is studied via 3D non-linear MHD modelling with the JOREK code....
Abstract The choice of first wall material is paramount importance for the plasma start-up conditions in ITER and future fusion power plants. In this context, present work focuses on correlations between impurity sources total radiated during tungsten (W) Environment Steady-state Tokamak (WEST). objective to highlight experimental indications a preferable combination scenario materials. Until 2019, WEST featured full high Z with all limiters exposing only W surfaces plasma. To study impact...
Abstract Plasma disruptions present a significant challenge to the viability of fusion energy production in tokamak reactors. Among disruption mitigation techniques, shattered pellet injection (SPI) has emerged as promising approach. The results presented this paper show novel findings impact nitrogen and neon seeding on sequence following SPI Joint European Torus (JET). This study exposes an order magnitude reduction pre-thermal quench duration for highly seeded plasmas pure deuterium SPI,...
Abstract WEST L-mode plasmas with dominant electron heating and no core torque source have observed improvements in confinement during boron (B) powder injection. These results are reminiscent of previous injection experiments on other devices gaseous impurity seeding WEST. During injection, the stored energy increased up to 25% due enhanced ion heat particle confinement. The were not indicative an L-H transition. To identify mechanisms causality chain behind these confinement, we employ...
Abstract The mission of WEST (tungsten-W Environment in Steady-state Tokamak) is to explore long pulse operation a full tungsten (W) environment for preparing next-step fusion devices (ITER and DEMO) with focus on testing the ITER actively cooled W divertor tokamak conditions. Following successful completion phase 1 (2016-2021), 2 started December 2022 lower made entirely ITER-grade mono-blocks. A boronization prior first plasma attempt allowed smooth startup new divertor. Despite reduced...
Experiments on the Pegasus ST are advancing physics and technology basis of local helicity injection (LHI). LHI injects with relatively intense electron current sources in plasma edge. It creates high toroidal current, toroidally-averaged tokamak-like plasmas that have been efficiently transitioned to Ohmically driven tokamak plasmas. Tradeoffs between engineering goals tested systems low-field-side high-field-side Pegasus, producing predominantly by non-solenoidal induction DC drive,...
Abstract H-mode is obtained at <?CDATA $A\sim 1.2$ ?> <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:mstyle displaystyle="false"> <mml:mrow> <mml:mi>A</mml:mi> <mml:mo>∼</mml:mo> <mml:mn>1.2</mml:mn> </mml:mrow> </mml:mstyle> </mml:math> in the Pegasus Toroidal Experiment via Ohmic heating, high-field-side fueling, and low edge recycling both limited diverted magnetic topologies. These plasmas show formation of current pressure pedestals a doubling energy...
Tokamak experiments at near-unity aspect ratio $A\ensuremath{\lesssim}1.2$ offer new insights into the self-organized $H$-mode plasma confinement regime. In contrast to conventional $A\ensuremath{\sim}3$ plasmas, $L\text{\ensuremath{-}}H$ power threshold ${P}_{LH}$ is $\ensuremath{\sim}15\ifmmode\times\else\texttimes\fi{}$ higher than scaling predictions, and it insensitive magnetic topology, consistent with modeling. Edge localized mode (ELM) instabilities shift lower toroidal numbers as...
Abstract The DIII-D tokamak has elucidated crucial physics and developed projectable solutions for ITER fusion power plants in the key areas of core performance, boundary heat particle transport, integrated scenario operation, with closing core-edge integration knowledge gap being overarching mission. New experimental validation high-fidelity, multi-channel, non-linear gyrokinetic turbulent transport models provides strong confidence it will achieve Q ⩾ 10 operation. Experiments identify...
Abstract Boron (B) powder injection is a potential alternative to glow discharge boronization as wall conditioning method for tokamaks. This technique currently being studied in WEST experiments, during which B injected by an Impurity Powder Dropper developed PPPL. In order interpret and analyse experimental trends, help develop future modelling workflow using boundary plasma simulation (SOLEDGE-EIRENE) ablation (Dust Injection Simulator) was tested. The effect of adding neutral source...
A major goal of the spherical tokamak (ST) research program is accessing a state low internal inductance ℓi, high elongation κ, and toroidal normalized beta (βt βN) without solenoidal current drive. Local helicity injection (LHI) in Pegasus ST [Garstka et al., Nucl. Fusion 46, S603 (2006)] provides non-solenoidally driven plasmas that exhibit these characteristics. LHI utilizes compact, edge-localized sources for plasma startup sustainment. It results hollow density profiles with ℓi. The...
A novel, cost-effective, multi-point Thomson scattering system has been designed, implemented, and operated on the Pegasus Toroidal Experiment. Leveraging advances in Nd:YAG lasers, high-efficiency volume phase holographic transmission gratings, increased quantum-efficiency Generation 3 image-intensified charge coupled device (ICCD) cameras, provides spectra at eight spatial locations for a single grating/camera pair. The on-board digitization of ICCD camera enables easy modular expansion,...
Access to and characterization of sustained, toroidally confined plasmas with a very high plasma-to-magnetic pressure ratio (${\ensuremath{\beta}}_{t}$), low internal inductance, elongation, nonsolenoidal current drive is central goal present tokamak plasma research. Stable access this desirable parameter space demonstrated in ultralow aspect elongation. Local helicity injection provides sustainment, ion heating. Equilibrium analyses indicate ${\ensuremath{\beta}}_{t}$ up...
Magnetic measurements during dc helicity injection tokamak startup indicate Alfv\'enic turbulence in the injected current streams mediates magnetic relaxation and results macroscopic plasma drive. Localization of such activity to streams, a bias voltage dependence its onset, higher-order spectral analysis super-Alfv\'enic electrons excite instabilities that drive observed turbulence. Measured fluctuation is consistent with an $\ensuremath{\alpha}$-dynamo electromotive force driving net...
A new control system for the Pegasus Thomson scattering diagnostic has recently been deployed to automate laser operation, data collection process, and interface with system-wide code. Automation extended areas outside of collection, such as manipulation beamline cameras remotely controlled turning mirror actuators enable intra-shot beam alignment. Additionally, upgraded a set fast (∼1 ms) mechanical shutters mitigate contamination from background light. Modification automation have improved...
Local helicity injection (LHI) is a non-solenoidal startup technique that utilizes electron current injectors at the plasma edge to initiate tokamak discharges. Viable techniques require high central Te combat resistive losses and enhance coupling auxiliary methods of drive/heating. Thomson scattering measurements LHI discharges in Pegasus showed peaked profiles Ip∼0.15 MA Bt∼0.15 T with Te,0∼100– 150 eV. These results are similar observed Ohmic induction. At lower levels Bt, were hollow...
This public data set contains openly-documented, machine readable digital research corresponding to figures published in D.J. Schlossberg et. al., 'A Novel, Cost-Effective, Multi-Point Thomson Scattering System on the Pegasus Toroidal Experiment,' Rev. Sci. Instrum. 87, 11E403 (2016).