Abstract: SiC matrix composite material, where heat-resistant long fiber such as carbon fiber is employed as a material for reinforcement and SiC is employed for the matrix, which significantly improves mechanical properties such as strength and toughness. The SiC matrix composite material, includes a SiC matrix and heat-resistant long fiber, wherein the SiC matrix includes both of alpha-type SiC and beta-type SiC, and the alpha-type SiC and the beta-type SiC are detected by micro-region X-ray diffraction with an X-ray beam diameter of no greater than 300 micrometers substantially at every region of every cross-section of the SiC matrix, the beta-type SiC has an average crystallite size that is no greater than 500 nm and greater than an average crystallite size of the alpha-type SiC, and the SiC matrix composite material has a porosity of no greater than 20% by volume.

Abstract: A composite silica glass made light diffusion member includes a dense silica glass, and a porous silica glass which has been layered on the surface of the dense silica glass. The porous silica glass is a porous body and has a homogeneous pore distribution. The porous body has a framework including a plurality of spherical silica glasses, contains a communicating pore part formed by spaces among them, and has a central pore size of 10 to 20 ?m and a porosity of 25 to 40%. The spherical silica glasses have an average diameter of 30 to 100 ?m. An average value of a specific arithmetic average roughness Ra in each of the spherical silica glass exposed on an outer surface of the porous silica glass is 0.8 to 4.0 nm.

Abstract: A composite silica glass made light diffusion member includes a dense silica glass, and a porous silica glass which has been layered on the surface of the dense silica glass. The porous silica glass is a porous body and has a homogeneous pore distribution. The porous body has a framework including a plurality of spherical silica glasses, contains a communicating pore part formed by spaces among them, and has a central pore size of 10 to 20 ?m and a porosity of 25 to 40%. The spherical silica glasses have an average diameter of 30 to 100 ?m. An average value of a specific arithmetic average roughness Ra in each of the spherical silica glass exposed on an outer surface of the porous silica glass is 0.8 to 4.0 nm.

Abstract: A decompression apparatus has an exhaust mechanism for decompressing a vacuum chamber. The exhaust mechanism has a main exhaust passage one end of which is connected to the vacuum chamber and the other end of which is connected to a vacuum pump, a first valve disposed in the main exhaust passage; a slow exhaust passage one end of which is connected to the vacuum chamber directly or via part of the main exhaust passage and the other end of which is connected to the vacuum pump directly or via part of the main exhaust passage, a cylindrical inorganic porous body disposed in the slow exhaust passage so that a gap is formed between the inorganic porous body and the inner surface of the slow exhaust passage, and a second valve disposed in the slow exhaust passage.

Abstract: A decompression apparatus has an exhaust mechanism for decompressing a vacuum chamber. The exhaust mechanism has a main exhaust passage one end of which is connected to the vacuum chamber and the other end of which is connected to a vacuum pump, a first valve disposed in the main exhaust passage; a slow exhaust passage one end of which is connected to the vacuum chamber directly or via part of the main exhaust passage and the other end of which is connected to the vacuum pump directly or via part of the main exhaust passage, a cylindrical inorganic porous body disposed in the slow exhaust passage so that a gap is formed between the inorganic porous body and the inner surface of the slow exhaust passage, and a second valve disposed in the slow exhaust passage.