Murakami density limit in tokamaks and reversed-field pinches

Technical Report · Thu Mar 01 00:00:00 EST 1984

DOI:https://doi.org/10.2172/5194209· OSTI ID:5194209

Perkins, F W; Hulse, R A

A theoretical upper limit for the density in an ohmically heated tokamak discharge follows from the requirement that the ohmic heating power deposited in the central current-carrying channel exceed the impurity radiative cooling in this critical region. A compact summary of our results gives this limit n/sub M/ for the central density as n/sub M/ = (Z/sub e//(Z/sub e/-1)/sup 1/2/n/sub eo/ (B/sub T//1T)(1m/R) where n/sub eo/ depends strongly on the impurity species and is remarkably independent of the central electron temperature T/sub e/(0). For T/sub e/(0) approx. 1 keV, we have n/sub eo/ = 1.5 x 10/sup 14/ cm/sup -3/ for beryllium, n/sub eo/ = 5 x 10/sup 13/ cm/sup -3/ for oxygen, n/sub eo/ = 1.0 x 10/sup 13/ cm/sup -3/ for iron, and n/sub eo/ = 0.5 x 10/sup 13/ cm/sup -3/ for tungsten. The results agree quantitatively with Murakami's original observations. A similar density limit, known as the I/N limit, exists for reversed-field pinch devices and this limit has also been evaluated for a variety of impurity species.

• Research Organization: Princeton Univ., NJ (USA). Plasma Physics Lab.
• DOE Contract Number: AC02-76CH03073
• OSTI ID: 5194209
• Report Number(s): PPPL-2087; ON: DE84009353
• Country of Publication: United States
• Language: English

Related Subjects

70 PLASMA PHYSICS AND FUSION TECHNOLOGY
700105* -- Fusion Energy-- Plasma Research-- Plasma Kinetics-Theoretical-- (-1987)
CLOSED PLASMA DEVICES
ELECTRIC HEATING
ELECTRON TEMPERATURE
HEATING
IMPURITIES
JOULE HEATING
PINCH EFFECT
PLASMA DENSITY
PLASMA HEATING
RESISTANCE HEATING
REVERSE-FIELD PINCH
THERMONUCLEAR DEVICES
TOKAMAK DEVICES