TY - GEN
T1 - Millimeter-wave assisted sintering of polycrystalline Yttria for laser host material
AU - Homstein, Melissa K.
AU - Bruce, Ralph W.
AU - Fliflet, Arne W.
AU - Gold, Steven H.
AU - Kahn, Manfred
AU - Imam, M. Ashraf
PY - 2007
Y1 - 2007
N2 - We report an investigation of millimeter-wave processing of yttria for fabrication of transparent, high-strength polycrystalline laser hosts for high energy laser (HEL) applications. Advantages of polycrystalline, compared to single-crystal laser host materials, include lower processing temperature, higher gain with flexibility of higher dopant concentrations, cheaper fabrication, and larger-size devices. Millimeter-wave processing is an alternative method to solve the problems of both conventional vacuum and low-frequency microwave sintering, such as low heating rate, poor coupling and thermal gradients. A major component of the millimeter-wave processing facility is a 20-kW, continuous-wave, 83-GHz gyrotron oscillator. Yttria has been successfully sintered with millimeter-wave beams with up to 99% theoretical density. A partially transparent yttria sample has also been achieved using the millimeter-wave sintering process [1]. Several factors impact the quality of the sintered material including the presence of agglomerates, impurities, processing atmosphere, sintering aids, and thermal gradients. Efforts to improve the transparency will be discussed.
AB - We report an investigation of millimeter-wave processing of yttria for fabrication of transparent, high-strength polycrystalline laser hosts for high energy laser (HEL) applications. Advantages of polycrystalline, compared to single-crystal laser host materials, include lower processing temperature, higher gain with flexibility of higher dopant concentrations, cheaper fabrication, and larger-size devices. Millimeter-wave processing is an alternative method to solve the problems of both conventional vacuum and low-frequency microwave sintering, such as low heating rate, poor coupling and thermal gradients. A major component of the millimeter-wave processing facility is a 20-kW, continuous-wave, 83-GHz gyrotron oscillator. Yttria has been successfully sintered with millimeter-wave beams with up to 99% theoretical density. A partially transparent yttria sample has also been achieved using the millimeter-wave sintering process [1]. Several factors impact the quality of the sintered material including the presence of agglomerates, impurities, processing atmosphere, sintering aids, and thermal gradients. Efforts to improve the transparency will be discussed.
KW - Ceramic
KW - Gyrotron
KW - Laser
KW - Laser host
KW - Millimeter-wave processing
KW - Polycrystalline
UR - http://www.scopus.com/inward/record.url?scp=38349121405&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=38349121405&partnerID=8YFLogxK
U2 - 10.4028/www.scientific.net/msf.561-565.511
DO - 10.4028/www.scientific.net/msf.561-565.511
M3 - Conference contribution
AN - SCOPUS:38349121405
SN - 0878494626
SN - 9780878494620
T3 - Materials Science Forum
SP - 511
EP - 514
BT - Selected, peer reviewed papers from The Sixth Pacific Rim International Conference on Advanced Materials and Processing, PRICM 6
PB - Trans Tech Publications Ltd
T2 - 6th Pacific Rim International Conference on Advanced Materials and Processing, PRICM 6
Y2 - 5 November 2007 through 9 November 2007
ER -