Transport suppression by diamagnetic phase shift as a possible mechanism to the L to H transition
- Univ. of Texas, Austin, TX (United States). Fusion Research Center
- Univ. of California, San Diego, La Jolla, CA (United States). Dept. of Physics
In the presence of a pressure gradient, the phase velocity of drift-wave or ITG-mode turbulence is different from the poloidal E{times}B rotation velocity of guiding centers. This results in an E{times}B turbulent particle diffusion being suppressed by the phase shift due to the diamagnetic rotation velocity {upsilon}{sub {theta}} = (c/enB)dP/dr. This shift cannot be eliminated by a frame change and affects the plasma transport. For {upsilon}{sub {theta}} well above the turbulent velocity v = {minus}c{gradient}{phi}{times}B/B{sup 2}, the radial diffusivity is suppressed as D {proportional_to} {upsilon}{sub {theta}}{sup {minus}3}. This results in a non-monotonous particle flux {Gamma}({gradient}n) {approx_equal} {minus}D{sub 0}{gradient}n[1+{alpha}({gradient}n){sup 2}]{sup 3/2} such as the transport can develop a bifurcation at a realistic density gradient.
- Research Organization:
- Texas Univ., Austin, TX (United States). Fusion Research Center; Texas Univ., Austin, TX (United States)
- Sponsoring Organization:
- USDOE, Washington, DC (United States)
- DOE Contract Number:
- FG05-88ER53266; FG03-94ER54241
- OSTI ID:
- 10103907
- Report Number(s):
- DOE/ER/53266--48; FRCR--451; ON: DE95003345
- Country of Publication:
- United States
- Language:
- English
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