1
|
Nishizawa T, Almagri AF, Anderson JK, Goodman W, Pueschel MJ, Nornberg MD, Ohshima S, Sarff JS, Terry PW, Williams ZR. Direct Measurement of a Toroidally Directed Zonal Flow in a Toroidal Plasma. Phys Rev Lett 2019; 122:105001. [PMID: 30932630 DOI: 10.1103/physrevlett.122.105001] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/25/2018] [Revised: 02/16/2019] [Indexed: 06/09/2023]
Abstract
Zonal flow appears in toroidal, magnetically confined plasmas as part of the self-regulated interaction of turbulence and transport processes. For toroidal plasmas having a strong toroidal magnetic field, the zonal flow is predominately poloidally directed. This Letter reports the first observation of a zonal flow that is toroidally directed. The measurements are made just inside the last closed flux surface of reversed field pinch plasmas that have a dominant poloidal magnetic field. A limit cycle oscillation between the strength of the zonal flow and the amplitude of plasma potential fluctuations is observed, which provides evidence for the self-regulation characteristic of drift-wave-type plasma turbulence. The measurements help advance understanding and gyrokinetic modeling of toroidal plasmas in the pursuit of fusion energy.
Collapse
Affiliation(s)
- T Nishizawa
- Department of Physics, University of Wisconsin-Madison, Madison, Wisconsin 53706, USA
| | - A F Almagri
- Department of Physics, University of Wisconsin-Madison, Madison, Wisconsin 53706, USA
| | - J K Anderson
- Department of Physics, University of Wisconsin-Madison, Madison, Wisconsin 53706, USA
| | - W Goodman
- Electrical Engineering Department, University of Wisconsin-Madison, Madison, Wisconsin 53706, USA
| | - M J Pueschel
- Institute for Fusion Studies, University of Texas at Austin, Austin, Texas 78712, USA
| | - M D Nornberg
- Department of Physics, University of Wisconsin-Madison, Madison, Wisconsin 53706, USA
| | - S Ohshima
- Institute of Advanced Energy, Kyoto University, Uji, Kyoto 611-0011, Japan
| | - J S Sarff
- Department of Physics, University of Wisconsin-Madison, Madison, Wisconsin 53706, USA
| | - P W Terry
- Department of Physics, University of Wisconsin-Madison, Madison, Wisconsin 53706, USA
| | - Z R Williams
- Department of Physics, University of Wisconsin-Madison, Madison, Wisconsin 53706, USA
| |
Collapse
|
2
|
Nishizawa T, Almagri AF, Goodman W, Ohshima S, Sarff JS. Development of a multi-channel capacitive probe for electric field measurements with fine spatial and high time resolution. Rev Sci Instrum 2018; 89:10J118. [PMID: 30399956 DOI: 10.1063/1.5035093] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/12/2018] [Accepted: 06/07/2018] [Indexed: 06/08/2023]
Abstract
A capacitive probe [Tan et al., Rev. Sci. Instrum. 88, 023502 (2017)] is one of a few diagnostics that is directly sensitive to the plasma potential. Using this diagnostic technique, a Multi-channel Linear Capacitive Probe (MLCP) is developed for turbulence measurements. The MLCP has 10 spatial channels and provides 9 points of radial electric field measurements simultaneously with a spatial step of 7 mm. A new readout circuit and a correction technique for low frequency attenuation are also developed to achieve the required spatial and time resolution. A performance test of the MLCP using a reversed field pinch plasma confirms that the MLCP resolves sub-centimeter structures of the equilibrium radial electric field profile and fluctuations up to 680 kHz.
Collapse
Affiliation(s)
- T Nishizawa
- Department of Physics, University of Wisconsin-Madison, Madison, Wisconsin 53706, USA
| | - A F Almagri
- Department of Physics, University of Wisconsin-Madison, Madison, Wisconsin 53706, USA
| | - W Goodman
- Electrical Engineering Department, University of Wisconsin-Madison, Madison, Wisconsin 53706, USA
| | - S Ohshima
- Institute of Advanced Energy, Kyoto University, Uji, Kyoto 611-0011, Japan
| | - J S Sarff
- Department of Physics, University of Wisconsin-Madison, Madison, Wisconsin 53706, USA
| |
Collapse
|
3
|
Fridström R, Chapman BE, Almagri AF, Frassinetti L, Brunsell PR, Nishizawa T, Sarff JS. Dependence of Perpendicular Viscosity on Magnetic Fluctuations in a Stochastic Topology. Phys Rev Lett 2018; 120:225002. [PMID: 29906181 DOI: 10.1103/physrevlett.120.225002] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/05/2017] [Revised: 03/21/2018] [Indexed: 06/08/2023]
Abstract
In a magnetically confined plasma with a stochastic magnetic field, the dependence of the perpendicular viscosity on the magnetic fluctuation amplitude is measured for the first time. With a controlled, ∼ tenfold variation in the fluctuation amplitude, the viscosity increases ∼100-fold, exhibiting the same fluctuation-amplitude-squared dependence as the predicted rate of stochastic field line diffusion. The absolute value of the viscosity is well predicted by a model based on momentum transport in a stochastic field, the first in-depth test of this model.
Collapse
Affiliation(s)
- R Fridström
- Department of Fusion Plasma Physics, School of Electrical Engineering, KTH Royal Institute of Technology, SE-10044 Stockholm, Sweden
| | - B E Chapman
- Department of Physics, University of Wisconsin-Madison, 1150 University Avenue, Madison, Wisconsin 53706, USA
| | - A F Almagri
- Department of Physics, University of Wisconsin-Madison, 1150 University Avenue, Madison, Wisconsin 53706, USA
| | - L Frassinetti
- Department of Fusion Plasma Physics, School of Electrical Engineering, KTH Royal Institute of Technology, SE-10044 Stockholm, Sweden
| | - P R Brunsell
- Department of Fusion Plasma Physics, School of Electrical Engineering, KTH Royal Institute of Technology, SE-10044 Stockholm, Sweden
| | - T Nishizawa
- Department of Physics, University of Wisconsin-Madison, 1150 University Avenue, Madison, Wisconsin 53706, USA
| | - J S Sarff
- Department of Physics, University of Wisconsin-Madison, 1150 University Avenue, Madison, Wisconsin 53706, USA
| |
Collapse
|
4
|
Anderson JK, Almagri AF, Chapman BE, Davydenko Y, Deichuli P, Den Hartog DJ, Forest CB, Fiksel G, Ivanov A, Liu D, Nornberg MD, Sarff JS, Stupishin N, Waksman J. Majority Ion Heating by Neutral Beam Injection and Confinement of Fast Ions in the Madison Symmetric Torus Reversed Field Pinch. Fusion Science and Technology 2017. [DOI: 10.13182/fst11-a11567] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Affiliation(s)
| | | | | | - y Davydenko
- Budker Institute of Nuclear Physics, Prospekt Lavrent’eva 11, Novosibirsk 630090, Russia
| | - P. Deichuli
- Budker Institute of Nuclear Physics, Prospekt Lavrent’eva 11, Novosibirsk 630090, Russia
| | | | | | - G. Fiksel
- University of Wisconsin, Madison WI 53706 USA;
- Laboratory for Laser Energetics, University of Rochester, Rochester NY 14610, USA
| | - A.A. Ivanov
- Budker Institute of Nuclear Physics, Prospekt Lavrent’eva 11, Novosibirsk 630090, Russia
| | - D. Liu
- University of Wisconsin, Madison WI 53706 USA;
| | | | - J. S. Sarff
- University of Wisconsin, Madison WI 53706 USA;
| | - N. Stupishin
- Budker Institute of Nuclear Physics, Prospekt Lavrent’eva 11, Novosibirsk 630090, Russia
| | - J. Waksman
- University of Wisconsin, Madison WI 53706 USA;
| |
Collapse
|
5
|
Anderson DT, Abdou A, Almagri AF, Anderson FSB, Canik JM, Guttenfelder W, Lechte C, Likin KM, Lu H, Oh S, Probert PH, Radder J, Sakaguchi V, Schmitt J, Talmadge JN, Zhai K, Brower DL, Deng C. Overview of Recent Results from HSX. Fusion Science and Technology 2017. [DOI: 10.13182/fst06-a1232] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Affiliation(s)
- D. T. Anderson
- University of Wisconsin-Madison HSX Plasma Laboratory, 1415 Engineering Drive, Madison, Wisconsin 53706
| | - A. Abdou
- University of Wisconsin-Madison HSX Plasma Laboratory, 1415 Engineering Drive, Madison, Wisconsin 53706
| | - A. F. Almagri
- University of Wisconsin-Madison HSX Plasma Laboratory, 1415 Engineering Drive, Madison, Wisconsin 53706
| | - F. S. B. Anderson
- University of Wisconsin-Madison HSX Plasma Laboratory, 1415 Engineering Drive, Madison, Wisconsin 53706
| | - J. M. Canik
- University of Wisconsin-Madison HSX Plasma Laboratory, 1415 Engineering Drive, Madison, Wisconsin 53706
| | - W. Guttenfelder
- University of Wisconsin-Madison HSX Plasma Laboratory, 1415 Engineering Drive, Madison, Wisconsin 53706
| | - C. Lechte
- University of Wisconsin-Madison HSX Plasma Laboratory, 1415 Engineering Drive, Madison, Wisconsin 53706
| | - K. M. Likin
- University of Wisconsin-Madison HSX Plasma Laboratory, 1415 Engineering Drive, Madison, Wisconsin 53706
| | - H. Lu
- University of Wisconsin-Madison HSX Plasma Laboratory, 1415 Engineering Drive, Madison, Wisconsin 53706
| | - S. Oh
- University of Wisconsin-Madison HSX Plasma Laboratory, 1415 Engineering Drive, Madison, Wisconsin 53706
| | - P. H. Probert
- University of Wisconsin-Madison HSX Plasma Laboratory, 1415 Engineering Drive, Madison, Wisconsin 53706
| | - J. Radder
- University of Wisconsin-Madison HSX Plasma Laboratory, 1415 Engineering Drive, Madison, Wisconsin 53706
| | - V. Sakaguchi
- University of Wisconsin-Madison HSX Plasma Laboratory, 1415 Engineering Drive, Madison, Wisconsin 53706
| | - J. Schmitt
- University of Wisconsin-Madison HSX Plasma Laboratory, 1415 Engineering Drive, Madison, Wisconsin 53706
| | - J. N. Talmadge
- University of Wisconsin-Madison HSX Plasma Laboratory, 1415 Engineering Drive, Madison, Wisconsin 53706
| | - K. Zhai
- University of Wisconsin-Madison HSX Plasma Laboratory, 1415 Engineering Drive, Madison, Wisconsin 53706
| | - D. L. Brower
- University of California-Los Angeles, Electrical Engineering Department 66-127J Engineering IV Building, Los Angeles, California 90095-1594
| | - C. Deng
- University of California-Los Angeles, Electrical Engineering Department 66-127J Engineering IV Building, Los Angeles, California 90095-1594
| |
Collapse
|
6
|
Bonofiglo PJ, Anderson JK, Almagri AF, Kim J, Clark J, Capecchi W, Sears SH, Egedal J. Development towards a fast ion loss detector for the reversed field pinch. Rev Sci Instrum 2016; 87:11D824. [PMID: 27910492 DOI: 10.1063/1.4959950] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
A fast ion loss detector has been constructed and implemented on the Madison Symmetric Torus (MST) to investigate energetic ion losses and transport due to energetic particle and MHD instabilities. The detector discriminates particle orbits solely on pitch and consists of two thin-foil, particle collecting plates that are symmetric with respect to the device aperture. One plate collects fast ion signal, while the second aids in the minimization of background and noise effects. Initial measurements are reported along with suggestions for the next design phase of the detector.
Collapse
Affiliation(s)
- P J Bonofiglo
- University of Wisconsin-Madison, Madison, Wisconsin 53706, USA
| | - J K Anderson
- University of Wisconsin-Madison, Madison, Wisconsin 53706, USA
| | - A F Almagri
- University of Wisconsin-Madison, Madison, Wisconsin 53706, USA
| | - J Kim
- University of Wisconsin-Madison, Madison, Wisconsin 53706, USA
| | - J Clark
- Florida Agricultural and Mechanical University, Tallahassee, Florida 32307, USA
| | - W Capecchi
- University of Wisconsin-Madison, Madison, Wisconsin 53706, USA
| | - S H Sears
- University of Wisconsin-Madison, Madison, Wisconsin 53706, USA
| | - J Egedal
- University of Wisconsin-Madison, Madison, Wisconsin 53706, USA
| |
Collapse
|
7
|
Ding WX, Lin L, Brower DL, Almagri AF, Chapman BE, Fiksel G, Den Hartog DJ, Sarff JS. Kinetic stress and intrinsic flow in a toroidal plasma. Phys Rev Lett 2013; 110:065008. [PMID: 23432267 DOI: 10.1103/physrevlett.110.065008] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/04/2012] [Indexed: 06/01/2023]
Abstract
A new mechanism for intrinsic plasma flow has been experimentally identified in a toroidal plasma. For reversed field pinch plasmas with a few percent β (ratio of plasma pressure to magnetic pressure), measurements show that parallel pressure fluctuations correlated with magnetic fluctuations create a kinetic stress that can affect momentum balance and the evolution of intrinsic plasma flow. This implies kinetic effects are important for flow generation and sustainment.
Collapse
Affiliation(s)
- W X Ding
- Department of Physics and Astronomy, University of California Los Angeles, Los Angeles, California 90095, USA
| | | | | | | | | | | | | | | |
Collapse
|
8
|
Lin L, Ding WX, Brower DL, Bergerson WF, Carter TA, Yates TF, Almagri AF, Chapman BE, Sarff JS. Role of nonlinear coupling and density fluctuations in magnetic-fluctuation-induced particle transport. Phys Rev Lett 2012; 108:175001. [PMID: 22680872 DOI: 10.1103/physrevlett.108.175001] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/04/2011] [Indexed: 06/01/2023]
Abstract
Three-wave nonlinear coupling among spatial Fourier modes of density and magnetic fluctuations is directly measured in a magnetically confined toroidal plasma. Density fluctuations are observed to gain (lose) energy from (to) either equilibrium or fluctuating fields depending on the mode number. Experiments indicate that nonlinear interactions alter the phase relation between density and magnetic fluctuations, leading to strong particle transport.
Collapse
Affiliation(s)
- L Lin
- Department of Physics and Astronomy, University of California Los Angeles, Los Angeles, California 90095, USA
| | | | | | | | | | | | | | | | | |
Collapse
|
9
|
Ren Y, Almagri AF, Fiksel G, Prager SC, Sarff JS, Terry PW. Experimental observation of anisotropic magnetic turbulence in a reversed field pinch plasma. Phys Rev Lett 2011; 107:195002. [PMID: 22181614 DOI: 10.1103/physrevlett.107.195002] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/06/2011] [Indexed: 05/31/2023]
Abstract
In this Letter we report an experimental study of fully developed anisotropic magnetic turbulence in a laboratory plasma. The turbulence has broad (narrow) spectral power in the perpendicular (parallel) direction to the local mean magnetic field extending beyond the ion cyclotron frequency. Its k[see symbol] spectrum is asymmetric in the ion and electron diamagnetic directions. The wave number scaling for the short wavelength fluctuations shows exponential falloff indicative of dissipation. A standing wave structure is found for the turbulence in the minor radial direction of the toroidal plasma.
Collapse
Affiliation(s)
- Y Ren
- Center for Magnetic Self-Organization in Laboratory and Astrophysical Plasmas, Department of Physics, University of Wisconsin-Madison, Madison, Wisconsin, USA
| | | | | | | | | | | |
Collapse
|
10
|
Magee RM, Den Hartog DJ, Kumar STA, Almagri AF, Chapman BE, Fiksel G, Mirnov VV, Mezonlin ED, Titus JB. Anisotropic ion heating and tail generation during tearing mode magnetic reconnection in a high-temperature plasma. Phys Rev Lett 2011; 107:065005. [PMID: 21902334 DOI: 10.1103/physrevlett.107.065005] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/31/2011] [Indexed: 05/31/2023]
Abstract
Complementary measurements of ion energy distributions in a magnetically confined high-temperature plasma show that magnetic reconnection results in both anisotropic ion heating and the generation of suprathermal ions. The anisotropy, observed in the C(+6) impurity ions, is such that the temperature perpendicular to the magnetic field is larger than the temperature parallel to the magnetic field. The suprathermal tail appears in the majority ion distribution and is well described by a power law to energies 10 times the thermal energy. These observations may offer insight into the energization process.
Collapse
Affiliation(s)
- R M Magee
- Department of Physics, University of Wisconsin-Madison, 53706, USA.
| | | | | | | | | | | | | | | | | |
Collapse
|
11
|
Clayton DJ, Almagri AF, Burke DR, Forest CB, Goetz JA, Kaufman MC, O'Connell R. An upgraded x-ray spectroscopy diagnostic on MST. Rev Sci Instrum 2010; 81:10E308. [PMID: 21034007 DOI: 10.1063/1.3478977] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/30/2023]
Abstract
An upgraded x-ray spectroscopy diagnostic is used to measure the distribution of fast electrons in MST and to determine Z(eff) and the particle diffusion coefficient D(r). A radial array of 12 CdZnTe hard-x-ray detectors measures 10-150 keV Bremsstrahlung from fast electrons, a signature of reduced stochasticity and improved confinement in the plasma. A new Si soft-x-ray detector measures 2-10 keV Bremsstrahlung from thermal and fast electrons. The shaped output pulses from both detector types are digitized and the resulting waveforms are fit with Gaussians to resolve pileup and provide good time and energy resolution. Lead apertures prevent detector saturation and provide a well-known etendue, while lead shielding prevents pickup from stray x-rays. New Be vacuum windows transmit >2 keV x-rays, and additional Al and Be filters are sometimes used to reduce low energy flux for better resolution at higher energies. Measured spectra are compared to those predicted by the Fokker-Planck code CQL3D to deduce Z(eff) and D(r).
Collapse
Affiliation(s)
- D J Clayton
- Department of Physics, University of Wisconsin-Madison, Madison, Wisconsin 53706, USA.
| | | | | | | | | | | | | |
Collapse
|
12
|
Fiksel G, Almagri AF, Chapman BE, Mirnov VV, Ren Y, Sarff JS, Terry PW. Mass-dependent ion heating during magnetic reconnection in a laboratory plasma. Phys Rev Lett 2009; 103:145002. [PMID: 19905576 DOI: 10.1103/physrevlett.103.145002] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/29/2009] [Indexed: 05/28/2023]
Abstract
Noncollisional ion heating in laboratory and astrophysical plasmas and the mechanism of conversion of magnetic energy to ion thermal energy are not well understood. In the Madison Symmetric Torus reversed-field pinch experiment, ions are heated rapidly during impulsive reconnection, attaining temperatures exceeding hundreds of eV, often well in excess of the electron temperature. The energy budget of the ion heating and its mass scaling in hydrogen, deuterium, and helium plasmas were determined by measuring the fraction of the released magnetic energy converted to ion thermal energy. The fraction ranges from about 10%-30% and increases approximately as the square root of the ion mass. A simple model based on stochastic ion heating is proposed that is consistent with the experimental data.
Collapse
Affiliation(s)
- G Fiksel
- Department of Physics, University of Wisconsin-Madison and Center for Magnetic Self-Organization in Laboratory and Astrophysical Plasmas, Madison, Wisconsin 53706, USA.
| | | | | | | | | | | | | |
Collapse
|
13
|
Deng CB, Brower DL, Breizman BN, Spong DA, Almagri AF, Anderson DT, Anderson FSB, Ding WX, Guttenfelder W, Likin KM, Talmadge JN. Energetic-electron-driven instability in the helically symmetric experiment. Phys Rev Lett 2009; 103:025003. [PMID: 19659216 DOI: 10.1103/physrevlett.103.025003] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/18/2009] [Indexed: 05/28/2023]
Abstract
Energetic electrons generated by electron cyclotron resonance heating are observed to drive instabilities in the quasihelically symmetric stellarator device. The coherent, global fluctuations peak in the plasma core and are measured in the frequency range of 20-120 kHz. Mode propagation is in the diamagnetic drift direction of the driving species. When quasihelical symmetry is broken, the mode is no longer observed. Experimental observations indicate that the unstable mode is acoustic rather than Alfvénic.
Collapse
Affiliation(s)
- C B Deng
- Department of Physics and Astronomy, University of California, Los Angeles, Los Angeles, California 90095, USA
| | | | | | | | | | | | | | | | | | | | | |
Collapse
|
14
|
Kuritsyn A, Fiksel G, Miller MC, Almagri AF, Reyfman M, Sarff JS. Probes for measuring fluctuation-induced Maxwell and Reynolds stresses in the edge of the Madison Symmetric Torus reversed field pinch. Rev Sci Instrum 2008; 79:10F127. [PMID: 19044611 DOI: 10.1063/1.2955930] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/27/2023]
Abstract
Several probes have been constructed to measure fluctuation-induced Maxwell and Reynolds stresses in the edge of the Madison Symmetric Torus reversed field pinch (RFP). The magnetic probe is composed of six magnetic pickup coil triplets. The triplets are separated spatially, which allows for local measurements of the Maxwell stress. To measure the plasma flow components for evaluation of the Reynolds stress, we employ a combination of an optical probe [Kuritsyn et al., Rev. Sci. Indrum. 77, 10F112 (2006)] and a Mach probe. The optical probe measures the radial ion flow locally using Doppler spectroscopy. The Mach probe consists of four current collectors biased negatively with respect to a reference tip and allows for measurements of the poloidal and toroidal components of the bulk plasma flow. The stresses are observed to play an important role in the momentum balance in the RFP edge during internal reconnection events.
Collapse
Affiliation(s)
- A Kuritsyn
- Center for Magnetic Self-Organization in Laboratory and Astrophysical Plasmas and Department of Physics, University of Wisconsin-Madison, Madison, Wisconsin 53706, USA.
| | | | | | | | | | | |
Collapse
|
15
|
Hansen AK, Almagri AF, Craig D, Hegna CC, Prager SC, Sarff JS. Momentum transport from nonlinear mode coupling of magnetic fluctuations. Phys Rev Lett 2000; 85:3408-3411. [PMID: 11030908 DOI: 10.1103/physrevlett.85.3408] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/05/2000] [Indexed: 05/23/2023]
Abstract
A cause of observed anomalous plasma momentum transport in a reversed-field pinch is determined experimentally. Magnetohydrodynamic theory predicts that nonlinear interactions involving triplets of tearing modes produce internal torques that redistribute momentum. Evidence for the nonlinear torque is acquired by detecting the correlation of momentum redistribution with the mode triplets, with the elimination of one of the modes in the triplet, and with the external driving of one of the modes.
Collapse
Affiliation(s)
- AK Hansen
- University of Wisconsin Department of Physics,1150 University Avenue, Madison, Wisconsin 53706, USA
| | | | | | | | | | | |
Collapse
|
16
|
Ji H, Yagi Y, Hattori K, Almagri AF, Prager SC, Hirano Y, Sarff JS, Shimada T, Maejima Y, Hayase K. Effect of collisionality and diamagnetism on the plasma dynamo. Phys Rev Lett 1995; 75:1086-1089. [PMID: 10060202 DOI: 10.1103/physrevlett.75.1086] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
|
17
|
Ji H, Almagri AF, Prager SC, Sarff JS. Time-resolved observation of discrete and continuous magnetohydrodynamic dynamo in the reversed-field pinch edge. Phys Rev Lett 1994; 73:668-671. [PMID: 10057507 DOI: 10.1103/physrevlett.73.668] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
|
18
|
Sarff JS, Assadi S, Almagri AF, Cekic M, Den Hartog DJ, Fiksel G, Hokin SA, Ji H, Prager SC, Shen W, Sidikman KL, Stoneking MR. Nonlinear coupling of tearing fluctuations in the Madison Symmetric Torus*. ACTA ACUST UNITED AC 1993. [DOI: 10.1063/1.860741] [Citation(s) in RCA: 21] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
|
19
|
Almagri AF, Assadi S, Prager SC, Sarff JS, Kerst DW. Locked modes and magnetic field errors in the Madison Symmetric Torus. ACTA ACUST UNITED AC 1992. [DOI: 10.1063/1.860473] [Citation(s) in RCA: 86] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022]
|
20
|
Rempel TD, Almagri AF, Assadi S, Den Hartog DJ, Hokin SA, Prager SC, Sarff JS, Shen W, Sidikman KL, Spragins CW, Sprott JC, Stoneking MR, Zita EJ. Turbulent transport in the Madison Symmetric Torus reversed‐field pinch. ACTA ACUST UNITED AC 1992. [DOI: 10.1063/1.860020] [Citation(s) in RCA: 25] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
|
21
|
Prager SC, Almagri AF, Assadi S, Beckstead JA, Dexter RN, Den Hartog DJ, Chartas G, Hokin SA, Lovell TW, Rempel TD, Sarff JS, Shen W, Spragins CW, Sprott JC. First results from the Madison Symmetric Torus reversed field pinch. ACTA ACUST UNITED AC 1990. [DOI: 10.1063/1.859557] [Citation(s) in RCA: 29] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
|