The effect of microwave heating on compact toroid plasmas
The spheromak, a subclass of self-contained closed magnetic configuration known as compact toroids, offers certain engineering advantages over a tokamak as a fusion reactor concept. It has been hampered, however, by a high transient radiation loss mechanism due primarily to impurities present in the plasma as a result of the discharge formation process. The power loss from the non-LTE, non-coronal line radiation from these plasmas results in a limitation on electron temperature, a [open quotes]radiation barrier[close quotes], which cannot be overcome simply with ohmic heating. Therefore, an auxiliary heating mechanism has been investigated as a means to burn through this radiation barrier. Microwave radiation has frequently been used as an auxiliary heating technique in magnetically confined plasmas. Specifically, heating at the lower hybrid resonance frequency of the plasma is investigated since (1) this externally applied RF wave has accessibility to the resonance layer of the compact toroid and (2) high power (20 MW) microwave generators are available in this frequency range ([approximately]430 MHz). A microwave generation and transmission system was constructed, installed, tested and used on the Berkeley Compact Torus Experiment (BCTX) along with a time-resolved radio-frequency spectroscopy diagnostic system. Ultraviolet optical spectroscopy and laser interferometry systems were also installed in order to assess the effect of the microwave before, during and after the heating event included measurement of density, plasma lifetime, magnetic field and electron temperature. The observed heating of the plasma was an increase in plasma lifetime and increased electron temperature. These results imply that lower hybrid heating has the capability to penetrate the radiation barrier.
- Research Organization:
- California Univ., Berkeley, CA (United States)
- OSTI ID:
- 5006755
- Resource Relation:
- Other Information: Thesis (Ph.D.)
- Country of Publication:
- United States
- Language:
- English
Similar Records
Preface to Special Topic: Advances in Radio Frequency Physics in Fusion Plasmas
Experimental studies of compact toroids
Related Subjects
SPHEROMAK DEVICES
PLASMA HEATING
MAGNETIC FIELDS
MICROWAVE RADIATION
PLASMA DENSITY
CLOSED PLASMA DEVICES
ELECTROMAGNETIC RADIATION
HEATING
RADIATIONS
THERMONUCLEAR DEVICES
TOKAMAK DEVICES
700350* - Plasma Production
Heating
Current Drive
& Interactions- (1992-)