Fast-ion D-alpha diagnostic development for the C-2W field-reversed configuration plasma

Bolte, N.; Nations, Marcel; Gupta, D.; Avilés, Juan Antonio Belmonte; Team, Tae

doi:10.1063/1.5036971

Cited by 3 publications

(1 citation statement)

References 10 publications

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“…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%

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 Diagnostic Suitementioning

confidence: 99%

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

Gota¹,

Binderbauer²,

Tajima³

et al. 2021

Nucl. Fusion

Self Cite

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Integrated diagnostic and data analysis system of the C-2W advanced beam-driven field-reversed configuration plasma experiment

Thompson

Schindler

Mendoza

et al. 2018

Review of Scientific Instruments

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The new C-2W experiment (also called Norman) at TAE Technologies, Inc. studies the evolution of field-reversed configuration (FRC) plasmas sustained by neutral beam injection. Data on the FRC plasma performance are provided by a comprehensive suite of diagnostics that includes over 700 magnetic sensors, four interferometer systems, multi-chord far-infrared polarimetry, two Thomson scattering systems, ten types of spectroscopic measurements, multiple fast imaging cameras with selectable atomic line filters, bolometry, reflectometry, neutral particle analyzers, and fusion product detectors. Most of these diagnostic systems are newly built using experience and data from the preceding C-2U experiment to guide the design process. A variety of commercial and custom acquisition electronics collect over 4000 raw signals from the C-2W diagnostics. These data are processed into physics results using a large-scale database of diagnostics metadata and analysis software, both built using open-source software tools.

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Active fast ion charge exchange measurements using a neutral particle analyzer and multiple beam species in C-2W

Kamio

Granstedt

Clary

et al. 2022

Review of Scientific Instruments

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In order to measure the fast ion using neutral particle analyzers (NPAs) in the low neutral density core region of a magnetic confinement fusion device, active change exchange measurements are often performed using a neutral beam (NB) as a charge-exchange (CX) target. One of the complications with this approach is that an NB injected as a CX target can also contribute to the total fast ion source. C-2W has a unique solution to this difficulty in that it is equipped with both eight NB injectors, which can inject beams of different particle species, and an electro-magnetic NPA (EM-NPA), which can measure multiple ion species simultaneously. This enables the active and passive fast ion CX components to be clearly distinguished. The decrease in amplitude of the CX spectra when a hydrogen NB is terminated was clearly observed by the EM-NPA in both hydrogen and deuterium channels. This reduction of observed fast ion flux was mainly caused by the diminished fast ion source, not crosstalk or a general reduction in fast ion confinement. As an example application of this technique on C-2W, fast ion behavior during a periodic density drop is explored. The large difference between the active and passive CX components of the EM-NPA signals clearly demonstrates the usefulness of the active fast ion CX measurement.

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Fast-ion D-alpha diagnostic development for the C-2W field-reversed configuration plasma

Cited by 3 publications

References 10 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

Integrated diagnostic and data analysis system of the C-2W advanced beam-driven field-reversed configuration plasma experiment

Active fast ion charge exchange measurements using a neutral particle analyzer and multiple beam species in C-2W

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