Murakami density limit in tokamaks and reversed-field pinches

Journal Article · Sat Jun 01 00:00:00 EDT 1985 · Phys. Fluids; (United States)

DOI:https://doi.org/10.1063/1.864927· OSTI ID:5816772

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 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//sup ///sup 2/ n/sub e/0 (B/sub T/ /1T) (1m/R), where n/sub e/0 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, n/sub e/0 = 1.5 x 10/sup 14/ cm/sup -3/ for beryllium, n/sub e/0 = 5.5 x 10/sup 13/ cm/sup -3/ for oxygen, n/sub e/0 = 1.0 x 10/sup 13/ cm/sup -3/ for iron and, n/sub e/0 = 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: Plasma Physics Laboratory, Princeton University, Princeton, New Jersey 08544
• DOE Contract Number: AC02-76CH03073
• OSTI ID: 5816772
• Journal Information: Phys. Fluids; (United States), Journal Name: Phys. Fluids; (United States) Vol. 28:6; ISSN PFLDA
• Country of Publication: United States
• Language: English

Related Subjects

70 PLASMA PHYSICS AND FUSION TECHNOLOGY
700101* -- Fusion Energy-- Plasma Research-- Confinement
Heating
& Production
ALKALINE EARTH METALS
BERYLLIUM
CLOSED PLASMA DEVICES
ELECTRIC HEATING
ELECTRON DENSITY
ELEMENTS
HEATING
IMPURITIES
IRON
JOULE HEATING
METALS
NONMETALS
OXYGEN
PINCH EFFECT
PLASMA
PLASMA DENSITY
PLASMA HEATING
RESISTANCE HEATING
REVERSE-FIELD PINCH
THERMONUCLEAR DEVICES
TOKAMAK DEVICES
TRANSITION ELEMENTS
TUNGSTEN