S.J. Wukitch
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View article: Simulation-based inference of high-field side scrape-off layer filament characteristics using density profile reflectometry
Simulation-based inference of high-field side scrape-off layer filament characteristics using density profile reflectometry Open
Simulation-based inference (SBI) is applied to high-field side (HFS) scrape-off layer (SOL) density profile reflectometry measurements on DIII-D, resulting in the inference of filament characteristics and fluctuation magnitudes. The predic…
View article: Mitigation of ICRF—edge plasma interaction in Alcator C-Mod
Mitigation of ICRF—edge plasma interaction in Alcator C-Mod Open
The parasitic interaction between ion cyclotron range of frequencies (ICRF) waves and the edge plasma has long limited high-power ICRF utilization in magnetically confined fusion plasmas. In this paper, we report on the successful mitigati…
View article: Optimization of the N∥ Upshift in the DIII-D high field side lower hybrid current drive experiment
Optimization of the N∥ Upshift in the DIII-D high field side lower hybrid current drive experiment Open
High field side lower hybrid current drive (LHCD) is one potential candidate for efficient non-inductive current drive in tokamak power plants, and the first test of this technology will occur on the DIII-D tokamak during the 2024 campaign…
View article: Evaluation of the Abel inversion integral in O-mode plasma reflectometry using Chebyshev–Gauss quadrature
Evaluation of the Abel inversion integral in O-mode plasma reflectometry using Chebyshev–Gauss quadrature Open
The Abel transform is often used to reconstruct plasma density profiles from O-Mode polarized reflectometry diagnostics. However, standard numerical trapezoidal evaluation of the Abel inversion integral can be computationally expensive for…
View article: Precipitate Size in GRCop-42 and GRCop-84 Cu-Cr-Nb Alloy Gas Atomized Powder and L-PBF Additive Manufactured Material
Precipitate Size in GRCop-42 and GRCop-84 Cu-Cr-Nb Alloy Gas Atomized Powder and L-PBF Additive Manufactured Material Open
Laser powder bed fusion (L-PBF) of Glenn Research Copper 42 or 84 (GRCop-42 or GRCop-84) produces a Cr2Nb precipitation-hardened high-conductivity copper alloy with tensile strength superior to other competing copper alloys. Precipitate di…
View article: Progress with applications of three-ion ICRF scenarios for fusion research: A review
Progress with applications of three-ion ICRF scenarios for fusion research: A review Open
Proceedings of the 24TH TOPICAL CONFERENCE ON RADIO-FREQUENCY POWER IN PLASMAS 26–28 September 2022 Annapolis, USA
View article: Predicted performance of a tangential viewing hard x-ray camera for the DIII-D high field side lower hybrid current drive experiment
Predicted performance of a tangential viewing hard x-ray camera for the DIII-D high field side lower hybrid current drive experiment Open
High field side launch of lower hybrid current drive (LHCD) has improved accessibility and penetration over low field side launch on DIII-D. Simulations predict single pass absorption under a wide range of plasma conditions. Hard x-ray (HX…
View article: The geometry of the ICRF-induced wave–SOL interaction. A multi-machine experimental review in view of the ITER operation
The geometry of the ICRF-induced wave–SOL interaction. A multi-machine experimental review in view of the ITER operation Open
As part of ITPA-Integrated Operational Scenario activities, this contribution reviews recent experimental characterizations of radio-frequency (RF)-induced scrape-off layer (SOL) modifications of various tokamaks worldwide and of the LArge…
View article: Physics and applications of three-ion ICRF scenarios for fusion research
Physics and applications of three-ion ICRF scenarios for fusion research Open
This paper summarizes the physical principles behind the novel three-ion scenarios using radio frequency waves in the ion cyclotron range of frequencies (ICRF). We discuss how to transform mode conversion electron heating into a new flexib…
View article: Physics basis for the ICRF system of the SPARC tokamak
Physics basis for the ICRF system of the SPARC tokamak Open
Ion cyclotron range of frequencies (ICRF) heating will be the sole auxiliary heating method on SPARC for both full-field ( B t 0 ~ 12 T) D–T operation and reduced field ( B t 0 ~ 8 T) D–D operation. Using the fast wave at ~120 MHz, good wa…
View article: Development of long-pulse heating and current drive actuators and operational techniques compatible with a high-Z divertor and first wall (Final Report)
Development of long-pulse heating and current drive actuators and operational techniques compatible with a high-Z divertor and first wall (Final Report) Open
MIT’s overall goal is to develop and collaboratively implement high Z material divertor capable of exhausting EAST’s heat flux in steady state, RF actuators to heat and drive current, and optimize operational scenarios compatible with high…
View article: Ion cyclotron range of frequency heating for SPARC
Ion cyclotron range of frequency heating for SPARC Open
Building on Alcator C-Mod experience and using the emerging technology of high-temperature superconducting magnet, SPARC is designed to be a compact (R0 = 1.65 m), high field (B0 = 12 T) pulsed tokamak to carry out D-T burning experiments …
View article: Aperture impedance matching for lower hybrid current drive launchers
Aperture impedance matching for lower hybrid current drive launchers Open
Circulating power within a multijunction launcher is both the system's greatest strength and a fundamental weakness. Although destructive interference of power reflected from the plasma interface at the multijunction results in low return …
View article: ICRF antenna matching systems with ferrite tuners for the Alcator C-Mod tokamak
ICRF antenna matching systems with ferrite tuners for the Alcator C-Mod tokamak Open
Real-time fast ferrite tuning (FFT) has been successfully implemented on the ICRF antennas on Alcator C-Mod. The former prototypical FFT system on the E-port 2-strap antenna has been upgraded using new ferrite tuners. A new FFT system with…
View article: Tests of advanced RF off-axis current drive techniques on DIII-D
Tests of advanced RF off-axis current drive techniques on DIII-D Open
The establishment of reactor-relevant radiofrequency heating and current drive techniques is a focus of work on DIII-D in the next five-year period. This paper gives an overview of the planned experimental work in the areas of (1) nearly v…
View article: Investigation of the critical edge ion heat flux for L-H transitions in Alcator C-Mod and its dependence on<i>B</i><sub>T</sub>
Investigation of the critical edge ion heat flux for L-H transitions in Alcator C-Mod and its dependence on<i>B</i><sub>T</sub> Open
Here, in this paper, we investigate the role of the edge ion heat flux for transitions from L-mode to H-mode in Alcator C-Mod. Previous results from the ASDEX Upgrade tokamak indicated that a critical value of edge ion heat flux per partic…
View article: X-ray observations of ${{\rm{K}}}_{\beta }$ emission from medium<i>Z</i>He-like ions in C-Mod tokamak plasmas
X-ray observations of ${{\rm{K}}}_{\beta }$ emission from medium<i>Z</i>He-like ions in C-Mod tokamak plasmas Open
X-ray spectra of n = 3 to 1 transitions in He-like ions (and satellites) from calcium, argon and chlorine have been measured in the core of Alcator C-Mod tokamak plasmas using high wavelength resolution x-ray spectrometer systems. The inte…
View article: On the<i>ρ</i><sub>∗</sub>scaling of intrinsic rotation in C-Mod plasmas with edge transport barriers
On the<i>ρ</i><sub>∗</sub>scaling of intrinsic rotation in C-Mod plasmas with edge transport barriers Open
Here, changes in the core intrinsic toroidal rotation velocity following L- to H- and L- to I-mode transitions have been investigated in Alcator C-Mod tokamak plasmas. The magnitude of the co-current rotation increments is found to increas…