Total magnetic reconnection during a tokamak major disruption

Technical Report · Sat Sep 01 04:00:00 EDT 1990

OSTI ID:5569926

Goetz, J A

Magnetic reconnection has long been considered to be the cause of sawtooth oscillations and major disruptions in tokamak experiments. Experimental confirmation of reconnection models has been hampered by the difficulty of direct measurement of reconnection, which would involve tracing field lines for many transits around the tokamak. Perhaps the most stringent test of reconnection in a tokamak involves measurement of the safety factor q. Reconnection arising from a single helical disturbance with mode numbers m and n should raise q to m/n everywhere inside of the original resonant surface. Total reconnection should also flatten the temperature and current density profiles inside of this surface. Disruptive instabilities have been studied in the Tokapole 2, a poloidal divertor tokamak. When Tokapole 2 is operated in the material limiter configuration, a major disruption results in current termination as in most tokamaks. However, when operated in the magnetic limiter configuration current termination is suppressed and major disruptions appear as giant sawtooth oscillations. The objective of this thesis is to determine if total reconnection is occurring during major disruptions. To accomplish this goal, the poloidal magnetic field has been directly measured in Tokapole 2 with internal magnetic coils. A full two-dimensional measurement over the central current channel has been done. From these measurements, the poloidal magnetic flux function is obtained and the magnetic surfaces are plotted. The flux-surface-averaged safety factor is obtained by integrating the local magnetic field line pitch over the experimentally obtained magnetic surface.

• Research Organization: Wisconsin Univ., Madison, WI (USA)
• Sponsoring Organization: DOE; USDOE, Washington, DC (USA)
• DOE Contract Number: FG02-85ER53198
• OSTI ID: 5569926
• Report Number(s): DOE/ER/53198-163; ON: DE91013637
• Country of Publication: United States
• Language: English

Related Subjects

70 PLASMA PHYSICS AND FUSION TECHNOLOGY
700101 -- Fusion Energy-- Plasma Research-- Confinement
Heating
& Production
700107* -- Fusion Energy-- Plasma Research-- Instabilities
700202 -- Fusion Power Plant Technology-- Magnet Coils & Fields
CLOSED PLASMA DEVICES
INTERNAL RING DEVICES
LIMITERS
MAGNETIC FIELD CONFIGURATIONS
MAGNETIC RECONNECTION
MAGNETIC SURFACES
OSCILLATIONS
PLASMA DIAGNOSTICS
PLASMA DISRUPTION
SAWTOOTH OSCILLATIONS
THERMONUCLEAR DEVICES
TOKAMAK DEVICES
TOKAPOLE DEVICES
TURBULENCE