TITLE

Heavy ion beam probe operation in time varying equilibria of improved confinement reversed field pinch discharges

AUTHOR(S)
Demers, D. R.; Chen, X.; Schoch, P. M.; Fimognari, P. J.
PUB. DATE
October 2010
SOURCE
Review of Scientific Instruments;Oct2010, Vol. 81 Issue 10, p10E109
SOURCE TYPE
Academic Journal
DOC. TYPE
Article
ABSTRACT
Operation of a heavy ion beam probe (HIBP) on a reversed field pinch is unique from other toroidal applications because the magnetic field is more temporal and largely produced by plasma current. Improved confinement, produced through the transient application of a poloidal electric field which leads to a reduction of dynamo activity, exhibits gradual changes in equilibrium plasma quantities. A consequence of this is sweeping of the HIBP trajectories by the dynamic magnetic field, resulting in motion of the sample volume. In addition, the plasma potential evolves with the magnetic equilibrium. Measurement of the potential as a function of time is thus a combination of temporal changes of the equilibrium and motion of the sample volume. A frequent additional complication is a nonideal balance of ion current on the detectors resulting from changes in the beam trajectory (magnetic field) and energy (plasma potential). This necessitates use of data selection criteria. Nevertheless, the HIBP on the Madison Symmetric Torus has acquired measurements as a function of time throughout improved confinement. A technique developed to infer the potential in the improved confinement reversed field pinch from HIBP data in light of the time varying plasma equilibrium will be discussed.
ACCESSION #
54858190

 

Related Articles

  • Observations of toroidicity-induced Alfvén eigenmodes in a reversed field pinch plasma. Regnoli, G.; Bergsåker, H.; Tennfors, E.; Zonca, F.; Martines, E.; Serianni, G.; Spolaore, M.; Vianello, N.; Cecconello, M.; Antoni, V.; Cavazzana, R.; Malmberg, J.-A. // Physics of Plasmas;Apr2005, Vol. 12 Issue 4, p042502 

    The article informs that plasmas confined in reversed field pinch configurations are characterized by relatively high amplitude of magnetic fluctuations (typically of the order of 1% of the average field) with a broad spectrum of frequencies and wave vectors. Most of the fluctuation power is...

  • Change of Paradigm for the Reversed Field Pinch. Escande, D. F. // AIP Conference Proceedings;11/23/2010, Vol. 1308 Issue 1, p85 

    The reversed field pinch (RFP) is a magnetic configuration germane to the tokamak, but it produces most of its magnetic field by the currents flowing inside the plasma; external coils provide only a small edge toroidal field whose sign is reversed with respect to the central one, whence the name...

  • Plasma Velocity Profile During The Pulsed Poloidal Current Drive In The MST RFP Plasma. Sakakita, H.; Craig, D.; Anderson, J. K.; Biewer, T. M.; Terry, S. D.; Chapman, B. E.; Den-Hartog, D. J. // AIP Conference Proceedings;2003, Vol. 669 Issue 1, p219 

    We report on the plasma velocity profile measurements during the pulsed poloidal current drive (PPCD) in the Madison Symmetric Torus (MST) reversed-field pinch (RFP). In order to decrease fluctuations due to dynamo activities, PPCD was applied to replace the dynamo electric field. As a result,...

  • Current profile control by alternating current magnetic helicity injection. Ebrahimi, F.; Prager, S. C. // Physics of Plasmas;May2004, Vol. 11 Issue 5, p2014 

    Current profile control by ac magnetic helicity injection is computationally investigated in a reversed field pinch (RFP). Three-dimensional resistive magnetohydrodynamics (MHD) computation is employed to study the nonlinear MHD. During ac helicity injection, when toroidal and toroidal surface...

  • Dynamo-free plasma in the reversed field pinch. Anderson, J. K.; Biewer, T. M.; Forest, C. B.; O'connell, R.; Prager, S. C.; Sarif, J. S. // Physics of Plasmas;May2004, Vol. 11 Issue 5, pL9 

    Transient application of a poloidal electric field to reversed field pinch (RFP) plasmas has led to a period in which dynamo activity (inherent in standard RFP plasmas) nearly vanishes. Measurements of the plasma resistivity, current density and electric field profiles show the edge-applied...

  • Transport Due to Intermittent Events and Plasma Flow Shear in Magnetized Plasmas. Antoni, V.; Regnoli, G.; Spolaore, M.; Serianni, G.; Vianello, N.; Cavazzana, R.; Spada, E.; Martines, E. // AIP Conference Proceedings;2003, Vol. 669 Issue 1, p191 

    In the Reversed Field Pinch experiment RFX a highly sheared ExB flow is observed in the edge region, with shear value close to the value required for turbulence suppression or reduction. Recent observations have shown that almost 50% of particle flux due to turbulence is due to intermittent...

  • Fivefold confinement time increase in the Madison Symmetric Torus using inductive poloidal... Stoneking, M.R.; Lanier, N.E.; Prager, S.C.; Sarff, J.S.; Sinitsyn, D. // Physics of Plasmas;May97, Vol. 4 Issue 5, p1632 

    Discusses the use of current profile control in the Madison Symmetric Torus reversed field pinch to reduce the magnetic fluctuations responsible for anomalous transport. Application of an inductive poloidal electric-field pulse to flatten the parallel current profile; Improvement in energy...

  • Measurement of current profile dynamics in the Madison Symmetric Torus. Terry, S.D.; Brower, D.L.; Ding, W.X.; Anderson, J.K.; Biewer, T.M.; Chapman, B.E.; Craig, D.; Forest, C.B.; O'Connell, R.; Prager, S.C.; Sarff, J.S. // Physics of Plasmas;Mar2004, Vol. 11 Issue 3, p1079 

    The current profile and core magnetic field fluctuation amplitudes in a reversed-field pinch are measured by using a high-resolution polarimetry–interferometry system. This paper presents data showing a redistribution of the current during a sawtooth crash. Also, the core magnetic field...

  • Development, tests, and data acquisition of the integrated system of internal sensors for RFX. Serianni, G.; Bolzonella, T.; Cavazzana, R.; Marchiori, G.; Pomaro, N.; Lotto, L.; Monari, M.; Taliercio, C. // Review of Scientific Instruments;Oct2004 Part I & II, Vol. 75 Issue 10, p4338 

    The RFX reversed field pinch (RFP) has undergone major modifications of the load assembly and is now equipped with a large number of active external coils for magnetohydrodynamics mode control. The study of the effects on the plasma of both the new passive structure and the active coils is then...

Share

Read the Article

Courtesy of VIRGINIA BEACH PUBLIC LIBRARY AND SYSTEM

Sorry, but this item is not currently available from your library.

Try another library?
Sign out of this library

Other Topics