Main ion charge exchange recombination spectroscopy on C-2W FRC plasmas

Gupta, D.; Nations, Marcel; Sweeney, J.; Avilés, Juan Antonio Belmonte; Leinweber, H. K.; Marshall, Ryan S.; Team, Tae

doi:10.1063/5.0043826

Cited by 6 publications

(5 citation statements)

References 15 publications

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“…While on the contrary, the magnitude of diamagnetic velocity for main ions is significantly higher as compared to the impurity (oxygen) ions, partly due to a lower Z for deuterium ions. As shown in figure 13, the estimated main-ion velocity is small (near zero, or below 15 km s −1 at the excluded-flux radius of FRC), which is consistent with the direct measurement of main-ion velocity using an active spectroscopy with diagnostic NB [37]. Observations of the low main-ion rotation velocity and the E × B rotation direction support and validate our understanding of FRC stabilization via edge biasing.…”

Section: Plasma Rotation and Velocity Shear Two Dedicatedsupporting

confidence: 83%

“…The diagnostics deployed on C-2W are required to provide data for a very wide range of plasma parameters to follow the discharge evolution from a seed FRC to a much hotter and higher energy state. Plasma performance and various other parameters are discerned using this comprehensive suite of diagnostics that includes: a variety of magnetic probes [29]; several iterations of bolometers; multiple interferometers including a far-infrared (FIR) interferometer/polarimeter [30], millimeter-wave interferometer [31], dispersion interferometer [32], and micrometer-wave interferometer [33]; core and jet region Thomson scattering systems [34,35]; spectroscopy of many varieties including impurity-and main-ion chargeexchange recombination spectroscopy (ChERS) [36,37], a combination doppler backscattering/cross-polarization scattering reflectometer [38], fast-ion D α spectrometer [39],…”

Section: Plasma Diagnostic Suitementioning

confidence: 99%

“…ChERS diagnostics are routinely used to measure impurity-ion (e.g. oxygen 6+) as well as main-ion (deuterium) toroidal (or azimuthal) velocities, temperatures, and density profiles near the midplane of C-2W, where the newly-developed diagnostic NB is utilized for active measurements [36,37]. The radial momentum balance equation for ions is given as…”

Section: Plasma Rotation and Velocity Shear Two Dedicatedmentioning

confidence: 99%

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Overview of C-2W: high temperature, steady-state beam-driven field-reversed configuration plasmas

Gota¹,

Binderbauer²,

Tajima³

et al. 2021

Nucl. Fusion

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TAE Technologies, Inc. (TAE) is pursuing an alternative approach to magnetically confined fusion, which relies on field-reversed configuration (FRC) plasmas composed of mostly energetic and well-confined particles by means of a state-of-the-art tunable energy neutral-beam (NB) injector system. TAE’s current experimental device, C-2W (also called ‘Norman’), is the world’s largest compact-toroid device and has made significant progress in FRC performance, producing record breaking, high temperature (electron temperature, T e > 500 eV; total electron and ion temperature, T tot > 3 keV) advanced beam-driven FRC plasmas, dominated by injected fast particles and sustained in steady-state for up to 30 ms, which is limited by NB pulse duration. C-2W produces significantly better FRC performance than the preceding C-2U experiment, in part due to Google’s machine-learning framework for experimental optimization, which has contributed to the discovery of a new operational regime where novel settings for the formation section and the confinement region yield consistently reproducible, hot, and stable plasmas. An active plasma control system has been developed and utilized in C-2W to produce consistent FRC performance as well as for reliable machine operations using magnets, electrodes, gas injection, and tunable NBs. The active control system has demonstrated stabilization of FRC axial instability. Overall FRC performance is well correlated with NBs and edge-biasing system, where higher total plasma energy is obtained by increasing both NB injection power and applied-voltage on biasing electrodes. C-2W divertors have demonstrated a good electron heat confinement on open-field-lines using strong magnetic mirror fields as well as expanding the magnetic field in the divertors (expansion ratio > 30); the energy lost per electron ion pair, η e ∼ 6–8, is achieved, which is close to the ideal theoretical minimum.

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Section: Plasma Rotation and Velocity Shear Two Dedicatedsupporting

confidence: 83%

Section: Plasma Diagnostic Suitementioning

confidence: 99%

Section: Plasma Rotation and Velocity Shear Two Dedicatedmentioning

confidence: 99%

See 1 more Smart Citation

Overview of C-2W: high temperature, steady-state beam-driven field-reversed configuration plasmas

Gota¹,

Binderbauer²,

Tajima³

et al. 2021

Nucl. Fusion

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“…The diagnostic beam injector for the C-2W facility (TAE, USA) forms a beam with an energy of 44 keV. High beam energy was chosen to ensure low beam attenuation in the et al 2021) and of the main deuterium ion component (Gupta et al 2021). The ion source is based on an arc plasma generator and its four-electrode IOS is made of chromium zirconium brass.…”

Section: Neutral Injectors For Plasma Diagnosticsmentioning

confidence: 99%

“…2021) and of the main deuterium ion component (Gupta et al. 2021). The ion source is based on an arc plasma generator and its four-electrode IOS is made of chromium zirconium brass.…”

Section: Neutral Injectors For Plasma Diagnosticsmentioning

confidence: 99%

Overview of neutral beam injectors for plasma heating and diagnostics developed at Budker INP

Shikhovtsev,

Ivanov,

Davydenko

et al. 2024

J. Plasma Phys.

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An overview of the neutral beam injectors developed at the Budker Institute of Nuclear Physics in Novosibirsk during the last 10 years is presented. These neutral injectors are used for plasma diagnostics, heating and current drive in modern fusion devices with magnetic confinement. An arc or a radio-frequency (RF) discharge generates a plasma in the ion sources of the injectors, and a positive hydrogen or deuterium ion beam is extracted and accelerated by a multiaperture ion-optical system (IOS). The accelerated ion beam is converted into a neutral one in a gas target. The precision multiaperture IOS with spherically concave electrodes provides ballistic focusing of the neutral beam. The high-energy, high-power beam injector based on negative ions, which is currently under development, is described as well. It comprises a RF negative ion source and a wide-aperture electrostatic accelerator separated from the source by a low-energy beam transport line, thereby improving the injector reliability.

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Fiber Bragg grating sensor array for detecting heat flux in vacuum

Titus,

Griswold,

Granstedt

et al. 2022

Review of Scientific Instruments

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In TAE Technologies’ current experimental device, C-2W (also called “Norman”), record-breaking, advanced beam-driven field-reversed configuration plasmas are produced and sustained in steady state utilizing variable energy neutral beams, advanced divertors, edge-biasing electrodes, and an active plasma control system [Gota et al., Nucl. Fusion 61, 106039 (2021)]. A novel diagnostic has been developed by TAE Technologies to leverage an industrial fiber Bragg grating (FBG) sensor array to detect heat flux along the wall of the vacuum vessel from a plasma discharge. The system consists of an optical fiber with FBG sensors distributed along its length, housed in a pressurized steel sheath. Each FBG sensor is constructed to reflect a different wavelength, the exact value of which is sensitive to the strain and temperature at the location of the grating in the fiber. The fiber is illuminated with broadband light, and the data acquisition system analyzes the spectrum of reflected light to determine the temperature at the location of each FBG. We have installed four of these vacuum-rated FBG sensor arrays on the C-2W experiment, each with 30 individual FBG sensors spaced at 0.15 m intervals along the 5 m fiber, with a 100 Hz acquisition rate. The measurement of temperature change due to a plasma discharge provides a single data point at each sensor location, creating a 120-point heat map of the vacuum vessel.

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Main ion charge exchange recombination spectroscopy on C-2W FRC plasmas

Cited by 6 publications

References 15 publications

Overview of C-2W: high temperature, steady-state beam-driven field-reversed configuration plasmas

Overview of C-2W: high temperature, steady-state beam-driven field-reversed configuration plasmas

Overview of neutral beam injectors for plasma heating and diagnostics developed at Budker INP

Fiber Bragg grating sensor array for detecting heat flux in vacuum

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