Enhanced pinch effect due to the electrostatic potential

K. C. Shaing, R. D. Hazeltine

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5 Citations (Scopus)


An inward particle pinch appears necessary to explain experimental results in tokamaks. Neither the neoclassical pinch effect, which is too small, nor the off-diagonal quasilinear term, which is usually outward in the trapped particle regime, can account for the observations. A mechanism for an enhanced inward pinch is proposed, based on results for an asymmetric magnetic field bump [Phys. Fluids 15, 2211 ( 1972)]. Because turbulent fluctuations also break toroidal symmetry, an enhanced inward pinch driven by the fluctuations and the Ohmic inductive field E is expected. To demonstrate this effect, an inward particle flux is calculated for a model tokamak configuration that has an electrostatic potential bump Φ0 at toroidal angle ζ= 2π. For the parameter regime r/R < eΦ0/ < 1, the flux is found to be Γ = - 4.47K(q)(r/R)L(Φ0)(υte/Rve) 1/2cNE/B, where r(R) is minor (major) radius, B is the magnetic field strength, υte is the electron thermal speed, νe is the electron-ion collision frequency, q is the safety factor, and K(q) and L(Φ0) are functions of q and Φ0, respectively. The results are also applicable to an asymmetric potential bump created externally to enhance the inward pinch flux of high energy, collisionless particles.

Original languageEnglish
Pages (from-to)2353-2357
Number of pages5
JournalPhysics of Fluids B
Issue number10
Publication statusPublished - 1990

All Science Journal Classification (ASJC) codes

  • Computational Mechanics
  • Condensed Matter Physics
  • Mechanics of Materials
  • General Physics and Astronomy
  • Fluid Flow and Transfer Processes


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