Dielectric changes in neutron-irradiated rf window materials

Conference · Thu Jan 01 04:00:00 EST 1987

DOI:https://doi.org/10.1016/0022-3115(88)90262-0· OSTI ID:5997119

Frost, H M; Clinard, Jr, F W

Ceramics used for windows in ECRH heating systems for magnetically-confined fusion reactors must retain adequate properties during and after intense neutron irradiation. Of particular concern is a decrease in transmissivity, a parameter inversely related to the product of dielectric constant K and loss tangent tandelta. Samples of polycrystalline Al/sub 2/O/sub 3/ and BeO were irradiated to 1 x 10/sup 26/ n/m/sup 2/ at 660K in the EBR-II fission reactor, and the above properties subsequently measured at 95 GHz. It was found that ktandelta for both materials doubled, implying a doubling of thermal stresses and a consequent reduction of time-to-failure from an assumed one year to 20 min for beryllia and 2 s for alumina. In the case of BeO, a large increase in reflectance of the incident millimeter-wave power results from dielectrically uncompensated swelling. This phenomenon could significantly degrade source performance.

• Research Organization: Los Alamos National Lab., NM (USA)
• DOE Contract Number: W-7405-ENG-36
• OSTI ID: 5997119
• Report Number(s): LA-UR-87-3283; CONF-871036-6; ON: DE88000482
• Country of Publication: United States
• Language: English

Related Subjects

70 PLASMA PHYSICS AND FUSION TECHNOLOGY
700209* -- Fusion Power Plant Technology-- Component Development & Materials Testing
ALKALINE EARTH METAL COMPOUNDS
ALUMINIUM COMPOUNDS
ALUMINIUM OXIDES
BERYLLIUM COMPOUNDS
BERYLLIUM OXIDES
CERAMICS
CHALCOGENIDES
DAMAGING NEUTRON FLUENCE
DIELECTRIC PROPERTIES
ECR HEATING
ELECTRICAL PROPERTIES
HEATING
HIGH-FREQUENCY HEATING
MATERIALS
MATERIALS TESTING
NEUTRON FLUENCE
OPENINGS
OXIDES
OXYGEN COMPOUNDS
PHYSICAL PROPERTIES
PLASMA HEATING
SERVICE LIFE
STRESSES
SWELLING
TESTING
THERMAL CONDUCTIVITY
THERMAL STRESSES
THERMODYNAMIC PROPERTIES
THERMONUCLEAR REACTOR MATERIALS
THERMONUCLEAR REACTORS
WAVEGUIDES
WINDOWS