Enhanced pinch effect due to electrostatic potential
- Oak Ridge National Lab., TN (USA)
- Texas Univ., Austin, TX (USA). Dept. of Physics
An inward 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. 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 {Phi}{sub 0} at toroidal angle {zeta} = 2{pi}. For the parameter regime r/R < e{Phi}{sub 0}/T{sub e} < 1, the flux is found to be {Gamma} = {minus}4.47K (q) (r/R) L({Phi}{sub 0})({upsilon}{sub te}/R{nu}e){sup 1/2}cN E/B, where r(R) is minor (major) radius, B is the magnetic field strength, {upsilon}{sub te} is the electron thermal speed, {nu}{sub e} is the electron-ion collision frequency, q is the safety factor, and K(q) and L({Phi}{sub 0}) are functions of q and {Phi}{sub 0} respectively. The results are also applicable to an asymmetric potential bump created externally to enhance the inward pinch flux of high energy, collisionless particles. 11 refs., 1 fig.
- Research Organization:
- Texas Univ., Austin, TX (USA). Inst. for Fusion Studies
- Sponsoring Organization:
- DOE/ER
- DOE Contract Number:
- FG05-80ET53088
- OSTI ID:
- 7016133
- Report Number(s):
- DOE/ET/53088-415; IFSR-415; ON: DE90007088; TRN: 90-006493
- Country of Publication:
- United States
- Language:
- English
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