Study of the confinement properties in a reversed-field pinch with mode rotation and gas fuelling

M. Cecconello, J.-A. Malmberg, P. Nielsen, R. Pasqualotto, J.R. Drake

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An extensive investigation of the global confinement properties in different operating scenarios in the rebuilt EXTRAP T2R reversed-field pinch (RFP) experiment is reported here. In particular, the role of a fast gas puff valve system, used to control plasma density, on confinement is studied. Without gas puffing, the electron density decays below 0.5 × 1019m-3. The poloidal beta varies between 5% and 15%, decreasing at large I/N. The energy confinement time ranges from 70 to 225 μs. With gas puffing, the density is sustained at ne≈ 1.5 × 1019m-3. However, a general slight deterioration of the plasma performances is observed for the same values of I/N: the plasma becomes cooler and more radiative. The poloidal beta is comparable to that in the scenarios without puff but the energy confinement time drops ranging from 60 to 130 μs. The fluctuation level and the energy confinement time have been found to scale with the Lundquist number as S-0.05±0.07and S0.5±0.1, respectively. Mode rotation is typical for all the discharges and rotation velocity is observed to increase with increasing electron diamagnetic velocity.
Original languageEnglish
Pages (from-to)1625 - 1638
Number of pages14
JournalPlasma Physics and Controlled Fusion
Issue number8
Publication statusPublished - Aug 2002
Externally publishedYes


All Science Journal Classification (ASJC) codes

  • Nuclear Energy and Engineering
  • Condensed Matter Physics

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