Abstract: In a gas generator comprising a cylindrical housing 1, gas generants 16 for generating gas by burning, which are charged in a plurality of combustion chambers 41 and 42 divided within the housing 1 and provided with orifices, and a plurality of ignitor devices 4 and 5 for burning the gas generants 16 within the respective combustion chambers 41 and 42 by spouting flame into the respective combustion chambers 41 and 42, wherein the ignitor devices 4 and 5 are arranged at each eccentric position from an axis of the housing 1, an enclosed space A for staying the generated gas discharged from the respective orifices 12 and 13 is formed at an outlet portion of the respective orifices 12 and 13 in the combustion chambers 41 and 42 having the ignitor devices arranged at the eccentric positions, and after passing through the enclosed space A, the gas is discharged from a gas discharge hole 14 formed in the housing 1.

Abstract: A carbon substrate manufacturing method includes a hot molding step, a burn-carbonizing step, a hot isostatical pressure treatment step, and a mirror polishing step. In the hot molding step, molding is performed while heating thermosetting resin powders to be a hard carbon substrate after burn-carbonizing, where the thermosetting resin powders are of a particle size 150 .mu.m or more, HPF 80-150 mm, a moisture content 1.0-3.0 weight %, Fe, Ni, Si and Ca respectively 5 ppm or less. In the burn-carbonizing process, a disk shaped resin molded body is filled into a graphite cylinder and burn-carbonized by heating from the external while the condition therefor is maintained in that the disk shaped resin molded body is stacked holding therein a graphite spacer at every one sheet basis or at every plurality of sheet basis and is loaded on its top with a tungsten carbide weight, where the graphite spacer has a heat conductivity 100 kcal/m.hr..degree. C. or less, a bulk density 1.70-1.85, and a flatness degree 10 .mu.