A5036484452- Magnetic confinement fusion research
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University of Wisconsin–Madison
2013-2024
Princeton Plasma Physics Laboratory
2021-2022
Oak Ridge National Laboratory
2022
Kyushu University
2021
Edgewood College
2021
The University of Tokyo
2021
National Institutes for Quantum Science and Technology
2021
CRC for Spatial information
2013
Curtin University
2013
Hutt Hospital
2005
Abstract This paper reviews the research on reversed field pinch (RFP) in last three decades. Substantial experimental and theoretical progress transformational changes have been achieved since review (Bodin 1990 Nucl. Fusion 30 1717–37). The experiments performed devices with different sizes capabilities. largest are RFX-mod Padova (Italy) MST Madison (USA). community includes also EXTRAP-T2R Sweden, RELAX Japan KTX China. Impressive improvements performance result of exploration two lines:...
We report the results of an experimental and theoretical international project dedicated to study quasi-single helicity (QSH) reversed field pinch (RFP) plasmas. The has involved several RFP devices numerical codes. It appears that QSH spectra are a robust feature common all experiments. Our expand reinforce evidence formation self-organized states with one dominant helical mode (Ohmic SH state) is approach complementary active control magnetic turbulence improve confinement in steady state RFP.
Reduction of core-resonant m=1 magnetic fluctuations and improved confinement in the Madison Symmetric Torus [Dexter et al., Fusion Technol. 19, 131 (1991)] reversed-field pinch have been routinely achieved through control surface poloidal electric field, but it is now known that has limited part by edge-resonant m=0 fluctuations. Now, refined field control, plus toroidal possible to reduce simultaneously This allowed high-energy runaway electrons, possibly indicative flux-surface...
Complementary measurements of ion energy distributions in a magnetically confined high-temperature plasma show that magnetic reconnection results both anisotropic heating and the generation suprathermal ions. The anisotropy, observed ${\mathrm{C}}^{+6}$ impurity ions, is such temperature perpendicular to field larger than parallel field. tail appears majority distribution well described by power law energies 10 times thermal energy. These observations may offer insight into energization process.
New developments in Faraday rotation polarimetry have provided the first measurements of current density profile and core magnetic fluctuations a high-temperature reversed field pinch. This has been achieved by fast-polarimeter system with time response up to 1 μs phase resolution <1 mrad. Recent experiments on Madison Symmetric Torus directly measured radial plasma interior amplitude 33 G, ∼1%. A broad spectrum is observed 100 kHz. Relaxation at sawtooth crash occurs timescale μs....
Improved confinement has been achieved in the MST through control of poloidal electric field, but it is now known that improvement limited by bursts an edge-resonant instability. Through refined field control, plus toroidal we have suppressed these bursts. This led to a total beta 15% and reversed-field-pinch-record estimated energy time 10 ms, tenfold increase over standard value which for first substantially exceeds scaling characterized most reversed-field-pinch plasmas.
Energy confinement comparable with tokamak quality is achieved in the Madison Symmetric Torus (MST) reversed field pinch (RFP) at a high beta and low toroidal magnetic field. Magnetic fluctuations normally present RFP are reduced via parallel current drive outer region of plasma. In response, electron temperature nearly triples doubles. The time increases ten-fold (to ∼10 ms), which L- H-mode scaling values for same plasma current, density, heating power, size shape. Runaway evidenced by...
The addition of dysprosium oxide nanoparticles is shown to improve the critical current in perpendicular magnetic fields for second-generation (2G) wire formed by metal–organic deposition (MOD). Typical enhancements Jc are from 0.17 MA cm−2 over 0.33 at 77 K and Bperp = 1.5 T. TEM analysis shows that we introducing (Y,Dy)2O3 with dimensions 10–50 nm. A simple theoretical maximum pinning effect additions expected excess concentrations approximately 70% DyO1.5, i.e. YBa2Cu3O7−δ+0.7DyO1.5 if...
Noncollisional ion heating in laboratory and astrophysical plasmas the mechanism of conversion magnetic energy to thermal are not well understood. In Madison Symmetric Torus reversed-field pinch experiment, ions heated rapidly during impulsive reconnection, attaining temperatures exceeding hundreds eV, often excess electron temperature. The budget its mass scaling hydrogen, deuterium, helium were determined by measuring fraction released converted energy. ranges from about 10%-30% increases...
With the exploration of MA plasma current regime in up to 0.5 s long discharges, RFX-mod has opened new and very promising perspectives for reversed field pinch (RFP) magnetic configuration, made significant progress understanding improving confinement controlling stability. A big leap with respect previous knowledge expectations on RFP physics performance been by since last 2006 IAEA Fusion Energy Conference. self-organized helical equilibrium experimentally achieved (the Single Helical...
Abstract. While traditionally used for surveying and photogrammetric fields, laser scanning is increasingly being a wider range of more general applications. In addition to the issues typically associated with processing point data, such applications raise number new complications, as complexity scenes scanned, along sheer volume data. Consequently, automated procedures are required processing, analysing This paper introduces method modelling multi-modal, geometrically complex objects in...
We report the first direct measurement of internal magnetic field structure associated with a 3D helical equilibrium generated spontaneously in core an axisymmetric toroidal plasma containment device. Magnetohydrodynamic bifurcation occurs reversed-field pinch when innermost resonant perturbation grows to large amplitude, reaching up 8% mean strength. Magnetic topology evolution is determined by measuring Faraday effect, revealing that, as grows, symmetry broken and established.
An overview of recent results from the MST programme on physics important for advancement reversed field pinch (RFP) as well improved understanding toroidal magnetic confinement more generally is reported. Evidence classical ions in RFP provided by analysis impurity and energetic created 1 MW neutral beam injection (NBI). The first appearance energetic-particle-driven modes NBI a plasma described. plasmas robustly access quasi-single-helicity state that has commonalities to stellarator...
The Wisconsin Manual for Assessing Psychotic-like Experiences is an interview-based assessment system rating psychotic and psychotic-like symptoms on a continuum of deviancy from normal to grossly psychotic. original manual contained six scales, assessing thought transmission, passivity experiences, withdrawal, auditory personally relevant aberrant beliefs, visual experiences. A seventh scale deviant olfactory experiences was subsequently added. scales have good interrater reliability when...
Plasma flow velocity fluctuations have been directly measured in the high-temperature magnetically confined plasma Madison Symmetric Torus (MST) Reversed-Field Pinch (RFP) [R. N. Dexter et al., Fusion Technol. 19, 131 (1991)]. These measurements show that are correlated with magnetic field such electromotive force 〈ṽ×B̃〉 approximately balances parallel Ohm’s law, E∥+〈ṽ×B̃〉∥=ηJ∥. This initial measurement is subject to limitations of spatial localization and other uncertainties, but evidence...
Evidence of a self-organized collapse towards narrow spectrum magnetic instabilities in the Madison Symmetric Torus [R. N. Dexter, D. W. Kerst, T. Lovell, S. C. Prager, and J. Sprott, Fusion Technol. 19, 131 (1991)] reversed field pinch device is presented. In this collapsed state, dubbed quasi-single helicity (QSH), modes condenses spontaneously to one dominant mode more completely than ever before observed. The amplitudes all but largest m=1 decrease QSH states. New results about thermal...
First measurements of the current-density profile in core a high-temperature reversed-field pinch are presented. The is observed to peak during sawtooth cycle and broaden promptly at crash. This change can be linked magnetic relaxation dynamo which predicted drive antiparallel current plasma core. For high-confinement discharges, suppressed strongly peak.
Current-carrying, toroidal laboratory plasmas typically cannot be sustained with an electron density above the empirical Greenwald limit. Presented here are tokamak experiments in Madison Symmetric Torus a up to unprecedented level about 10 times this This is thought made possible part by thick, stabilizing, conductive wall, and high-voltage, feedback-controlled power supply driving plasma current. The radial profile of current flattens around twice limit, without edge collapse routinely...
A biased electrode is used in the Madison Symmetric Torus (MST) reversed-field pinch [Fusion Technol. 19, 131 (1991)] to manipulate plasma flow order study damping and momentum transport. Finite radial conductivity allows a current, which provides toroidal torque that spins up plasma. The applied balanced by viscous force opposes acceleration. From viscosity inferred be anomalous. transport of comparable particles energy, consistent with stochastic magnetic field lines.
Large radial electric field gradients, leading to sheared $\mathbf{E}\ifmmode\times\else\texttimes\fi{}\mathbf{B}$ flow, are observed in enhanced confinement discharges the Madison Symmetric Torus reversed-field pinch. The flow shear develops a narrow region plasma edge. Electrostatic fluctuations reduced over entire edge with an extra reduction region. Magnetic fluctuations, resonant core but global extent, also reduced. of is presumably due strong shear, causes reductions outside this have...
The bulk fluid velocity is measured spectroscopically with 10 μs time resolution in the Madison Symmetric Torus (MST) reversed-field pinch (RFP) [Fusion Technol. 19, 131 (1991)], a diagnostic capability used to study fast flow dynamics associated locked modes and RFP dynamo. phase of tearing accelerate between sawtooth events, reaching maximum speed about 20 km/s few ms. Both slow down at crash ≊100 μs. This deceleration scale as calculated for from action electromagnetic torque on magnetic...
We report an increase in particle confinement with plasma biasing a reversed field pinch. Miniature sources are used as electrodes to negatively bias the at edge $(r/a\ensuremath{\sim}0.9)$. Particle content increases and ${\mathrm{H}}_{\ensuremath{\alpha}}$ radiation decreases upon application of global roughly doubles result. Energy is not significantly affected by edge. Measurements potential, impurity flow, floating potential fluctuations indicate that strong flows produced electrostatic reduced.
Growth to large amplitude of a single core-resonant tearing mode in the Madison Symmetric Torus [R. N. Dexter et al., Fusion Technol. 19, 131 (1991)] reversed-field pinch is accompanied by braking and eventual cessation rotation. There also concurrent deceleration bulk plasma The shown be well described time-dependent version magnetohydrodynamical model Fitzpatrick Phys. Plasmas 6, 3878 (1999)] which torque originates from eddy currents induced rotating conducting shell surrounding plasma....
Abstract The Madison Symmetric Torus (MST) is a toroidal device that, when operated as standard tokamak, does not have major disruptions. Unlike most tokamaks, the MST plasma surrounded by close fitting highly conducting wall, with resistive wall penetration time two orders of magnitude longer than in JET or DIII-D, and three times ITER. can operate edge <?CDATA $q_a \leqslant 2$?> <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:mrow> <mml:msub>...