K.H. Burrell
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Identification of a window for quiescent H-mode operation in MHD stability diagram of DIII-D plasmas Open
A window for quiescent H-mode (QH-mode) operation in DIII-D plasmas in the diagram of pedestal magnetohydrodynamic (MHD) stability was identified through linear MHD stability analysis, accounting for the effects of plasma rotation and ion …
View article: Progress in pedestal and edge physics: Chapter 3 of the special issue: on the path to tokamak burning plasma operation
Progress in pedestal and edge physics: Chapter 3 of the special issue: on the path to tokamak burning plasma operation Open
This paper describes the extensive progress that has been made in the understanding of tokamak pedestal physics since the 2007 publication of ‘Progress in the ITER Physics Basis’ (Ikeda 2007 Nucl. Fusion 47 E01–S500). It serves as Chapter …
The role of ion-scale micro-turbulence in pedestal width of the DIII-D wide-pedestal QH mode Open
The low-edge rotation, intrinsically ELM-free, and improved confinement wide-pedestal quiescent H-mode (QH-mode), discovered in DIII-D tokamak, has pedestal widths exceeding the EPED-kinetic-ballooning mode (KBM) model scaling typically by…
Successfully Transitioning an Interruptive Alert into a Noninterruptive Alert for Central Line Dressing Changes in the Neonatal Intensive Care Unit Open
Background Interruptive alerts are known to be associated with clinician alert fatigue, and poorly performing alerts should be evaluated for alternative solutions. An interruptive alert to remind clinicians about a required peripherally in…
Local measurements of the pedestal magnetic field profile throughout the ELM cycle on DIII-D Open
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…
View article: Explaining the lack of power degradation of energy confinement in wide pedestal quiescent H-modes via transport modeling
Explaining the lack of power degradation of energy confinement in wide pedestal quiescent H-modes via transport modeling Open
Wide pedestal quiescent H (WPQH)-mode is an attractive scenario for future burning plasmas as they operate without ELMs. WPQH is characterized by formation of a wider and higher pedestal (than quiescent H-mode), and broadband fluctuations …
Numerical modeling of pedestal stability and broadband turbulence of wide-pedestal QH-mode plasmas on DIII-D Open
The wide-pedestal quiescent high confinement mode discovered on DIII-D in recent years is a stationary and quiescent H-mode (QH-mode) with the pedestal width exceeding EPED prediction by at least 25%. Its characteristics, such as low rotat…
View article: Comparison of thermal and angular momentum transport in neutral beam-heated hot-ion H- and L-mode discharges in DIII-D
Comparison of thermal and angular momentum transport in neutral beam-heated hot-ion H- and L-mode discharges in DIII-D Open
We have carried out experiments using the hot-ion mode of operation to compare the bulk transport in L-mode and H-mode discharges. These experiments have demonstrated that the confinement improvement in the bulk of the plasma in DIII-D is …
Stabilization of kink/peeling modes by coupled rotation and ion diamagnetic drift effects in quiescent H-mode plasmas in DIII-D and JT-60U Open
Magnetohydrodynamic stability at the edge pedestal in several quiescent H-mode (QH-mode) plasmas in DIII-D and JT-60U experiments was analyzed by considering plasma rotation and ion diamagnetic drift effects. It was identified that a kink/…
Turbulence-driven flow dynamics in general axisymmetric toroidal geometry Open
This work gives the equations governing the generation of toroidally axisymmetric flows by turbulent Reynolds and Maxwell stresses in finite aspect ratio, general cross section tokamak plasmas. Inclusion of the divergence-free flow constra…
Atomic Models for Motional Stark Effects Diagnostics Open
We present detailed atomic physics models for motional Stark effects (MSE) diagnostic on magnetic fusion devices. Excitation and ionization cross sections of the hydrogen or deuterium beam traveling in a magnetic field in collisions with e…
View article: Examination of stiff ion temperature gradient mode physics in simulations of DIII-D H-mode transport
Examination of stiff ion temperature gradient mode physics in simulations of DIII-D H-mode transport Open
A systematic evaluation of gyrokinetic and gyrofluid model predictions of ion temperature gradient (ITG) stability and transport using parameters from DIII-D high confinement mode (H-mode) plasmas has been performed. The nonlinear CGYRO co…
Charge exchange recombination spectroscopy measurements of DIII-D poloidal rotation with poloidal asymmetry in angular rotation Open
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) …
Impact of shape on pedestal characteristics in the wide pedestal quiescent H-mode in the DIII-D tokamak Open
Experiments on the DIII-D tokamak have advanced the operational limits of wide pedestal quiescent H-mode plasmas towards increased ITER relevance by simultaneously demonstrating well-matched plasma shape and net zero injected torque. Wide …
Expanding the parameter space of the wide-pedestal QH-mode towards ITER conditions Open
Significant parameter space expansion of the wide-pedestal quiescent H-mode (QH-mode) towards more ITER and reactor relevant conditions has been achieved in the DIII-D tokamak. Recent experiments reveal this naturally ELM-free regime can o…
Towards validated MHD modeling of edge harmonic oscillation in DIII-D QH-mode discharges Open
The extended-MHD NIMROD code (Sovinec C.R. and King J.R. 2010 J. Comput. Phys. 229 5803) is used to simulate the dynamics of an edge harmonic oscillation (EHO) in quiescent H-mode (QH-mode) DIII-D (Luxon J.L. 2002 Nucl. Fusion 42 614) disc…
Role of sheared <i>E × B</i> flow in self-organized, improved confinement states in magnetized plasmas Open
A major scientific success story of magnetic fusion research in the past several decades has been the theoretical development and experimental testing of the process of turbulence decorrelation and stabilization by sheared E × B flow, whic…
Creation and sustainment of wide pedestal quiescent H-mode with zero net neutral beam torque Open
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…
Experimental characterization of the effect of <i>E</i> × <i>B</i> shear on edge-harmonic oscillation mode structure Open
The Edge Harmonic Oscillation (EHO) mode is one of the characteristic modes that provides an edge transport channel during high-confinement ELM-free phase (the so-called Quiescent High confinement phase). Recent theoretical work and extens…
Relative intensity calibration of the DIII-D charge-exchange recombination spectroscopy system using neutral beam injection into gas Open
A new calibration method for the DIII-D charge-exchange spectroscopy system produces a smoother impurity density profile compared to previous techniques, improving the accuracy of the impurity density profile reconstruction. The relative i…
Using motional Stark splitting of Dα emission to constrain MHD equilibrium analysis in DIII-D plasmas Open
We report tests of an alternate technique for constraining MHD equilibrium analysis in tokamak plasmas using internal magnetic field measurements based on |B| measurements from the motional Stark splitting of Dα spectral lines emitted by a…
Active spectroscopy measurements of the deuterium temperature, rotation, and density from the core to scrape off layer on the DIII-D tokamak (invited) Open
Main-ion charge exchange recombination spectroscopy (MICER) uses the neutral beam induced Dα spectrum to measure the local deuterium ion (D+) temperature, rotation, and density, as well as parameters related to the neutral beams, fast ions…
Main ion and impurity edge profile evolution across the L- to H-mode transition on DIII-D Open
Detailed measurements of the main ion (D+) and impurity ion (C6+) evolution during the development of the H-mode pedestal across an L-H transition show significant differences in toroidal rotation, density, and temperature profiles in the …
Synthetic diagnostic for assessing spatial averaging of charge exchange recombination spectroscopy measurements Open
A synthetic charge exchange recombination spectroscopy diagnostic based on the FIDASIM modeling suite has been created for the DIII-D tokamak. This synthetic diagnostic assumes that the ions have Maxwellian distribution functions on each f…
Scaling trends of the critical <i>E</i> × <i>B</i> shear for edge harmonic oscillation onset in DIII-D quiescent H-mode plasmas Open
Quiescent H-mode (QH-mode) has been identified as an attractive stationary operational regime in tokamaks due to its lack of edge localized modes (ELMs), along with good particle and impurity control aided by the presence of magnetohydrody…
Deuterium charge exchange recombination spectroscopy from the top of the pedestal to the scrape off layer in H-mode plasmas Open
Recent completion of the thirty two channel main-ion (deuterium) charge exchange recombination spectroscopy (CER) diagnostic on DIII-D enables detailed comparisons between impurity and main-ion temperature, density, and toroidal rotation. …
The effect of electron cyclotron heating on density fluctuations at ion and electron scales in ITER baseline scenario discharges on the DIII-D tokamak Open
Experiments simulating the ITER Baseline Scenario on the DIII-D tokamak show that torque-free pure electron heating, when coupled to plasmas subject to a net co-current beam torque, affects density fluctuations at electron scales on a sub-…
<b>E</b> × <b>B</b>flow shear drive of the linear low-<i>n</i>modes of EHO in the QH-mode regime Open
A new mechanism is identified for driving the edge harmonic oscillations (EHOs) in the quiescent H-mode (QH-mode) regime, where a strong E × B flow shear destabilizes low-n kink/peeling modes, separately from the previously found Kelvin-He…