A5029304810- Magnetic confinement fusion research
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Tri Alpha Energy (United States)
2014-2025
Harvard University
2025
Massachusetts General Hospital
2025
NIMS University
2024
Bose Institute
2023
North Bengal University
2023
Tata Institute of Fundamental Research
2023
University of Wisconsin–Madison
2004-2010
University of Maryland, College Park
2005
Institute for Plasma Research
2000-2003
Conventional field-reversed configurations (FRCs), high-beta, prolate compact toroids embedded in poloidal magnetic fields, face notable stability and confinement concerns. These can be ameliorated by various control techniques, such as introducing a significant fast ion population. Indeed, adding neutral beam injection into the FRC over past half-decade has contributed to striking improvements stability. Further, addition of electrically biased plasma guns at ends, end plugs, advanced...
The present status of experiments on zonal flows in magnetic confinement is examined. innovative use traditional and modern diagnostics has revealed unambiguously the existence flows, their spatio-temporal characteristics, relationship to turbulence effects confinement. In particular, a number observations have been accumulated oscillatory branch named geodesic acoustic modes, suggesting necessity for theories give proper description. addition these basic properties several new methods...
A hot stable field-reversed configuration (FRC) has been produced in the C-2 experiment by colliding and merging two high-β plasmoids preformed dynamic version of θ-pinch technology. The process exhibits highest poloidal flux amplification obtained a magnetic confinement system (over tenfold increase). Most kinetic energy is converted into thermal with total temperature (T{i}+T{e}) exceeding 0.5 keV. final FRC state record lifetime approaching classical values. These findings should have...
TAE Technologies' research is devoted to producing high temperature, stable, long-lived field-reversed configuration (FRC) plasmas by neutral-beam injection (NBI) and edge biasing/control. The newly constructed C-2W experimental device (also called 'Norman') the world's largest compact-toroid (CT) device, which has several key upgrades from preceding C-2U such as higher input power longer pulse duration of NBI system well installation inner divertors with upgraded electrode biasing systems....
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 a state-of-the-art tunable energy neutral-beam (NB) injector system. TAE's current experimental device, C-2W (also called 'Norman'), the world's largest compact-toroid device has made significant progress in FRC performance, producing record breaking, high temperature...
Characteristics and scaling properties of the geodesic acoustic mode (GAM), a coherent, radially-sheared high frequency (~15?kHz) zonal flow oscillation, are studied systematically using time-delay-estimation techniques applied to localized, multi-point density fluctuation measurements obtained by beam emission spectroscopy on DIII-D. The GAM amplitude is shown increase strongly with increasing safety factor, q95, likewise become undetectably small for q95 < 4.2, qualitatively consistent...
A low-frequency, spectrally broad (Deltaf approximately 10 kHz) poloidal flow structure that peaks near zero frequency is observed in time-resolved measurements of the turbulence velocity field core region (r/a 0.6-0.9) DIII-D tokamak plasmas. These flows exhibit a long wavelength (low m) and short radial coherence length comparable to ambient decorrelation length. Characteristics these are consistent with theoretically predicted residual or zero-mean-frequency zonal flows.
Field reversed configurations (FRCs) with high confinement are obtained in the C-2 device by combining plasma gun edge biasing and neutral beam injection. The creates an inward radial electric field that counters usual FRC spin-up. n = 2 rotational instability is stabilized without applying quadrupole magnetic fields. FRCs nearly axisymmetric, which enables fast ion confinement. also produces E × B shear layer, may explain observed improved particle transport. times factors to 4, lifetimes...
Tri Alpha Energy's experimental program has demonstrated reliable field-reversed configuration (FRC) formation and sustainment, driven by fast ions via high-power neutral-beam (NB) injection. The world's largest compact-toroid device, C-2U, was upgraded from C-2 with the following key system upgrades: increased total NB input power ~4 MW (20 keV hydrogen) to 10+ (15 tilted injection angle; enhanced edge-biasing capability inside of each end divertor for boundary/stability control. C-2U...
Beam Emission Spectroscopy (BES), a high-sensitivity, good spatial resolution imaging diagnostic system, has been deployed and recently upgraded expanded at the DIII-D tokamak to better understand density fluctuations arising from plasma turbulence. The currently system images over an approximately 5 × 7 cm region mid-plane (radially scannable 0.2 < r/a ≤ 1) with 6 (radial poloidal) grid of rectangular detection channels, one microsecond time resolution. BES observes collisionally-induced,...
A high temperature field reversed configuration (FRC) has been produced in the newly built, world’s largest compact toroid (CT) facility, C-2, by colliding and merging two high-β CTs using advanced field-reversed θ-pinch technology. This long-lived, stable merged state exhibits following key properties: (1) apparent increase poloidal flux from first pass to final state, (2) significantly improved confinement compared conventional FRCs with decay rates approaching classical values some cases,...
Analysis techniques to measure the time-resolved flow field of turbulence are developed and applied images density fluctuations obtained with beam emission spectroscopy diagnostic system on DIII-D tokamak. Velocimetry applications include measurement turbulent particle flux, zonal flows, Reynolds stress. The eddies exhibits quasisteady poloidal flows as well high-frequency radial motion associated electrostatic potential strongly nonlinear multifield interactions. orthogonal dynamic...
Large field reversed configurations (FRCs) are produced in the C-2 device by combining dynamic formation and merging processes. The good confinement of these FRCs must be further improved to achieve sustainment with neutral beam (NB) injection pellet fuelling. A plasma gun is installed at one end attempt electric control FRC edge layer. inward radial counters usual spin-up mitigates n = 2 rotational instability without applying quadrupole magnetic fields. Better centering also obtained,...
Abstract TAE Technologies’ fifth-generation fusion device, C-2W (also called ‘Norman’), is the world’s largest compact-toroid device and has made significant progress in field-reversed configuration (FRC) plasma performance. produces record breaking, macroscopically stable, high-temperature advanced beam-driven FRC plasmas, dominated by injected fast particles sustained steady state, which primarily limited neutral-beam (NB) pulse duration. The NB power supply system recently been upgraded...
Theoretical models taking into account different feedback source terms (e.g., ion-impact electron emission, photo-electron field etc) have been proposed for the existence and explanation of shape negative corona current pulse, including step on leading edge. In present work, a pulse with edge is obtained in presence emission only. The explained plasma formation process enhancement source. Ionization wave-like movement toward cathode observed after step. conditions without edge, are also...
An upgraded beam emission spectroscopy (BES) system has been deployed to access low amplitude turbulence regions near internal transport barriers on the DIII-D tokamak. Sixteen high sensitivity channels are being installed. A significant increase in total signal noise is achieved by: (1) Increased spatial volume sampling tailored known characteristics; (2) increased throughput spectrometer assembly isolate local fluorescence, coupled new large area photoconductive photodiodes; (3) sharp edge...
An upgraded beam emission spectroscopy (BES) diagnostic has been developed and deployed at the DIII-D tokamak to achieve a dramatic increase in sensitivity small-scale density fluctuations. This BES system incorporates high-throughput silica optical fiber bundles (1.62mm2-ster per channel), ultra fast spectrometer collection optics, custom-designed high-transmission interference filters, large-area photodiodes. The bundle images are optimized match measured radial poloidal asymmetries of...
A versatile heterodyne Doppler Backscattering (DBS) system is used to measure density fluctuation levels (in the wavenumber range kρs ≤ 50), and toroidal E × B flow velocity in C-2 Field-Reversed Configuration (FRC). Six tunable frequencies three waveguide bands (26 GHz f 90 GHz) are launched using monostatic beam optics, via a quasi-optical combiner/polarizer an adjustable parabolic focusing mirror (inside vacuum enclosure) achieving Gaussian spot sizes of 3–5.5 cm at X/O-mode cutoff. The...
A significant improvement of field reversed configuration (FRC) lifetime and plasma confinement times in the C-2 plasma, called High Performance FRC regime, has been observed with neutral beam injection (NBI), improved edge stability, better wall conditioning [Binderbauer et al., Phys. Plasmas 22, 056110 (2015)]. Quasi-1D (Q1D) fluid transport code developed employed to carry out analysis such conditions. The Q1D is coupled a Monte-Carlo incorporate effect fast ions, due NBI, on background...
In TAE Technologies' C-2W experiment, electrode biasing is utilized for boundary control of a field-reversed configuration (FRC) plasma embedded in magnetic mirror. Understanding the underlying physics associated with FRC rotation, stabilization, and heating crucial improving machine performance. Impurity ion rotation temperature are sensitive to effects, measurements these quantities can provide insight into important dynamics overall effectiveness system. To this end, charge-exchange...
Two Doppler spectroscopy diagnostics with complementary capabilities are developed to measure the ion temperatures and velocities of FRC plasmas in C-2 device. First, multichord doppler diagnostic can simultaneously 15 chords plasma using an image intensified camera. Second, a single-chord fast-response provides much higher faster time response by 16-channel photo-multiplier tube array. To study neutral density deuterium under different wall conditions, highly sensitive eight-channel D-alpha...
A two-chord λIR∼3.39 μm He–Ne laser interferometer system was developed for a flux-coil-generated field-reversed configuration to estimate the electron density and total temperature of (FRC) plasma. This heterodyne consists single ∼2 mW infrared laser, visible (λvis∼632.8 nm) alignment, 40 MHz acousto-optic modulator, photodetectors, quadrature phase detectors. Initial measurement performed measured average densities were 2–10×1019 m−3 at two different radial positions in midplane. time...
A new time-delay estimation (TDE) technique based on dynamic programming is developed to measure the time-varying between two signals. The TDE provides a frequency response five ten times better than previously known techniques, namely, those time-lag cross-correlation or wavelet analysis. Effects of spectrum, signal-to-noise ratio, and amplitude (represented as transfer function) are studied using simulated data function for decreases with increase in noise signal; however it independent...