An electrical connector includes an insulative housing and a plurality of contacts received in the housing. Reactant gas injector and exhaust apparatus are positioned to concentrate a forceful supply of reactant gas across each wafer at a speed in excess of 10 cmsec. The controller has an abnormality diagnosis function of detecting abnormality, and thus holds the data monitored immediately before when abnormality is detected. The card cage includes a base wall to support the cover plate, and a bent wall.