Explanipedia

Challenges and approaches to interpretive modeling of boundary plasma and neutral transport in a closed, pumped divertor Open

R.S. Wilcox, M.W. Shafer, J. Lore, J.M. Canik, S. R. Haskey , et al. · 2025

An experimental discharge from the DIII-D tokamak is modeled using the SOLPS-ITER code suite and compared against measurements in the pumped and relatively closed upper divertor. Uncertainties of boundary plasma simulations are identified …

A study of resistive peeling–ballooning modes across spherical tokamaks Open

A. Kleiner, K. Imada, F. Ebrahimi, N.M. Ferraro, S. R. Haskey , et al. · 2025

We investigate how non-ideal-magnetohydrodynamics (MHD) effects, in particular plasma resistivity, impact the peeling–ballooning stability thresholds in spherical tokamaks. This analysis follows the discovery of resistive kink-peeling mode…

Understanding the L-H isotope effect at the DIII-D tokamak and advancements in synthetic turbulence diagnostics Open

Kyle Callahan, L. Schmitz, Quinn Pratt, Troy Carter, G. Wang , et al. · 2024

It is determined that while heat flux differences between hydrogen and deuterium isotope experiments result from natural differences in carbon impurity content at DIII-D, it is not the origin of the low to high confinement mode (L-H) trans…

Nonlinear gyrokinetic modelling of high confinement negative triangularity plasmas Open

A. Marinoni, M. E. Austin, J. Candy, C. Chrystal, S. R. Haskey , et al. · 2024

Nonlinear gyrokinetic simulations correctly predict particle as well as ion and electron energy fluxes of high confinement plasmas with a negative triangularity cross sectional shape, showing that core transport in these plasmas is well de…

Broadening of the Divertor Heat Flux Profile in High Confinement Tokamak Fusion Plasmas with Edge Pedestals Limited by Turbulence in DIII-D Open

D. R. Ernst, A. Bortolon, C. S. Chang, S. Ku, F. Scotti , et al. · 2024

Multimachine empirical scaling predicts an extremely narrow heat exhaust layer in future high magnetic field tokamaks, producing high power densities that require mitigation. In the experiments presented, the width of this exhaust layer is…

Inter-ELM pedestal turbulence dynamics dependence on q95 and temperature gradient Open

Z. Yan, G. R. McKee, Jamie Xia, Xiang Jian, R. J. Groebner , et al. · 2024

A series of dedicated experiments from the DIII-D tokamak provide spatially and temporally resolved measurements of electron density and temperature, and multiscale and multichannel fluctuations over a wide range of conditions. Measurement…

Decoupling of peeling and ballooning thresholds for pedestal stability and reduction in ELM frequency via enhanced turbulence with edge electron cyclotron heating in DIII-D Open

Santanu Banerjee, K. Barada, C. Chrystal, R. J. Groebner, S. Mordijck , et al. · 2024

The edge localized mode (ELM) frequency ( f ELM ) decreased by 63% when electron cyclotron heating (ECH) deposition location is shifted from ρ = 0.4 to ρ = 0.8 in DIII-D discharges where the power ratio between neutral beam injection (NBI)…

Aligning the Thomson scattering and charge exchange recombination diagnostics using neutral beam emission at DIII-D Open

A. Feyrer, S. R. Haskey, C. Chrystal, C. Aidala · 2024

This work addresses discrepancies in the alignment of the H-mode pedestal profiles of the electron and ion properties in the DIII-D tokamak as measured by Thomson Scattering (TS) and Charge Exchange Recombination Spectroscopy (CER) diagnos…

Isotope impact on Alfvén eigenmodes and fast ion transport in DIII-D Open

M. A. Van Zeeland, E.M. Bass, Xiaodi Du, W. W. Heidbrink, C. Chrystal , et al. · 2024

Measurements of beam driven Alfvén Eigenmode (AE) activity in matched deuterium (D) and hydrogen (H) DIII-D plasmas show a dramatic difference in unstable mode activity and fast ion transport for a given injected beam power. The dependence…

Broadening of the Divertor Heat Flux Profile in High Confinement Tokamak Fusion Plasmas with Edge Pedestals Limited by Turbulence in DIII-D Open

D. R. Ernst, A. Bortolon, C. S. Chang, S. Ku, F. Scotti , et al. · 2024

Multi-machine empirical scaling predicts an extremely narrow heat exhaust layer in future high magnetic field tokamaks, producing high power densities that require mitigation. In the experiments presented, the width of this exhaust layer i…

Density wavenumber spectrum measurements, synthetic diagnostic development, and tests of quasilinear turbulence modeling in the core of electron-heated DIII-D H-mode plasmas Open

Quinn Pratt, V. H. Hall-Chen, Tom Neiser, R. Hong, J. Damba , et al. · 2023

Measurements of the turbulent density wavenumber spectrum, , using the Doppler Back-Scattering (DBS) diagnostic are reported from DIII-D H-mode plasmas with electron cyclotron heating as the only auxiliary heating method. These…

On the origin of the DIII-D L-H power threshold isotope effect Open

Kyle J. Callahan, L. Schmitz, Troy Carter, E. A. Belli, C. Chrystal , et al. · 2023

The increased low to high confinement mode (L to H-mode) power threshold in DIII-D low collisionality hydrogen plasmas (compared to deuterium) is shown to result from lower impurity (carbon) content, consistent with reduced (mass-dep…

Micro-tearing mode dominated electron heat transport in DIII-D H-mode pedestal Open

J. Chen, Xiang Jian, D.L. Brower, S. R. Haskey, Z. Yan , et al. · 2023

A new, comprehensive set of evidence reveals that Micro-Tearing Modes (MTMs) dominate pedestal electron heat transport in an H-mode experiment in the DIII-D tokamak. The experiment investigates the role of MTMs by scanning pedestal collisi…

Role of edge-localized neoclassical tearing modes in quiescent H-mode plasmas in the DIII-D tokamak Open

Qiming Hu, R. Nazikian, Xi Chen, Q. Yu, M. E. Austin , et al. · 2023

The edge-harmonic oscillations (EHOs) in standard quiescent H-mode (QH-mode) plasmas in DIII-D are consistent with edge-localized neoclassical tearing modes (NTMs) based on nonlinear two-fluid MHD simulations. Using kinetic equilibria cons…

Turbulence characteristics and flow dynamics impacts on the H-mode transition in favourable magnetic geometry with lower power threshold Open

Z. Yan, G. R. McKee, L. Schmitz, P. Gohil, S. R. Haskey · 2023

The L-H transition power threshold ( P LH ) in favourable magnetic geometry (ion ∇ B drift pointing towards X-point) is much lower than in the unfavourable magnetic geometry (ion ∇ B drift pointing away from X-point) on multiple tokamaks. …

Reducing the L-H transition power threshold in ITER-similar-shape DIII-D hydrogen plasmas Open

L. Schmitz, R.S. Wilcox, D. Shiraki, T. L. Rhodes, Z. Yan , et al. · 2022

Recent dedicated DIII-D experiments in low-torque, ITER-similar-shape (ISS) hydrogen plasmas (at a plasma current I p ∼ 1.5 MA and ITER-similar edge safety factor q 95 ∼ 3.6) show that the L-H transition power threshold P LH can be reduced…

Details of the neutral energy distribution and ionization source using spectrally resolved Balmer-alpha measurements on DIII-D Open

S. R. Haskey, B. A. Grierson, L. Stagner, C. Chrystal, A. Bortolon , et al. · 2022

Spectrally resolved passive Balmer-α (D-α, H-α) measurements from the DIII-D 16 channel edge main-ion charge exchange recombination system confirm the presence of higher energy neutrals (“thermal” neutrals) in addition to the cold neutrals…

Local measurements of the pedestal magnetic field profile throughout the ELM cycle on DIII-D Open

M.G. Burke, R. J. Fonck, G. R. McKee, K.H. Burrell, S. R. Haskey , et al. · 2022

New high speed localized measurements of the pedestal magnetic field during the edge localized mode (ELM) cycle of a DIII-D High confinement mode (H-mode) discharge indicate a temporally and spatial complex redistribution of the edge curre…

Investigation of core impurity transport in DIII-D diverted negative triangularity plasmas Open

F. Sciortino, N. T. Howard, T. Odstrčil, M. E. Austin, I. Bykov , et al. · 2022

Tokamak operation at negative triangularity has been shown to offer high energy confinement without the typical disadvantages of edge pedestals (Marinoni et al 2021 Nucl. Fusion 61 116010). In this paper, we examine impurity transport in D…

Studies of EC pre-ionization in DIII-D to support development of ITER plasma initiation Open

J. Sinha, P.C. de Vries, M.L. Walker, D. J. Battaglia, F. Turco , et al. · 2022

New experiments have been conducted at DIII-D to improve the physics understanding of plasma initiation assisted by electron cyclotron (EC) wave injection, allowing better extrapolation to ITER. This has been achieved by applying an EC pul…

Dynamic measurement of impurity ion transport in runaway electron plateaus in DIII-D Open

E.M. Hollmann, A. Bortolon, F. Effenberg, N.W. Eidietis, D. Shiraki , et al. · 2022

The first dynamic (time-dependent) measurements of impurity ion radial (cross field) and parallel (along-field) diffusion coefficients for post-disruption runaway electron plateaus are presented. Small (∼1 mm diameter) carbon or silicon pe…

Ion thermal transport in the H-mode edge transport barrier on DIII-D Open

S. R. Haskey, Arash Ashourvan, Santanu Banerjee, K. Barada, E. A. Belli , et al. · 2022

The power balance ion heat flux in the pedestal region on DIII-D increases and becomes increasingly anomalous (above conventional neoclassical) in experiments with higher temperature and lower density pedestals where the ion collisionality…

New understanding of inter-ELM pedestal turbulence, transport, and gradient behavior in the DIII-D tokamak Open

K. Barada, T. L. Rhodes, S. R. Haskey, R. J. Groebner, A. Diallo , et al. · 2021

New observations of pedestal localized turbulence in the inter-ELM period of H-mode plasmas in DIII-D show that ion temperature gradient mode scale (ITG-scale) density fluctuation (ñ) increases immediately after each ELM crash and is quick…

Testing the DIII-D co/counter off-axis neutral beam injected power and ability to balance injected torque Open

B. A. Grierson, M. A. Van Zeeland, J. T. Scoville, B. Crowley, I. Bykov , et al. · 2021

DIII-D has undergone a major upgrade and successfully injected high power off-axis neutral beams (~4 MW) in both co-current and counter-current directions. This capability of high power co/counter steerable off-axis neutral beams on a majo…

Radially resolved active charge exchange measurements of the hydrogenic isotope fraction on DIII-D Open

S. R. Haskey, L. Stagner, B. A. Grierson, C. Chrystal, Genevieve DeGrandchamp , et al. · 2021

Radially resolved hydrogenic isotope fraction measurement capabilities have been developed for DIII-D using the main-ion charge exchange recombination (MICER) spectroscopy system in preparation for mixed hydrogen and deuterium experiments.…

Charge exchange recombination spectroscopy measurements of DIII-D poloidal rotation with poloidal asymmetry in angular rotation Open

C. Chrystal, S. R. Haskey, K.H. Burrell, B. A. Grierson, C. Collins · 2021

Sixteen new tangential views for the charge exchange recombination (CER) spectroscopy diagnostic at DIII-D were installed in 2019 on the high-field side (HFS) of the tokamak with the main goal being the measurement of main-ion (deuterium) …

Creation and sustainment of wide pedestal quiescent H-mode with zero net neutral beam torque Open

K.H. Burrell, Xi Chen, C. Chrystal, D. R. Ernst, B. A. Grierson , et al. · 2020

Recent experiments on DIII-D have shown it is possible to create and sustain wide pedestal quiescent H-mode (QH-mode) plasmas with zero net torque from neutral beam injection (NBI) for the full discharge duration. Wide pedestal QH-mode has…

Predicting the rotation profile in ITER Open

C. Chrystal, B. A. Grierson, S. R. Haskey, A.C. Sontag, F. M. Poli , et al. · 2019

Determining the toroidal rotation for future tokamaks like ITER is a challenging and important problem. By combining empirical scalings for the intrinsic rotation at the top of the pedestal with the expected neutral beam torque and modelin…

Integrated Zeff analysis on the DIII-D Tokamak Open

Kyle Callahan, C. Chrystal, B. A. Grierson, S. R. Haskey, W. W. Heidbrink , et al. · 2019

Determination of effective ion charge, or Zeff, from measurements of visible brems\\-strahlung radiation made by multiple diagnostics is now integrated into a single analysis workflow within the plasma profile analysis module in OMFIT [Log…

Formation of a High Pressure Staircase Pedestal with Suppressed Edge Localized Modes in the DIII-D Tokamak Open

Arash Ashourvan, R. Nazikian, E. A. Belli, J. Candy, D. Eldon , et al. · 2019

We observe the formation of a high-pressure staircase pedestal (≈16-20 kPa) in the DIII-D tokamak when large amplitude edge localized modes are suppressed using resonant magnetic perturbations. The staircase pedestal is characterized by a …

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