CONTROL OF FLOW OF VAPOR SUBLIMATED FROM SOLID

PROBLEM TO BE SOLVED: To provide a new system controlling flow of vapor sublimated from solid. SOLUTION: A vapor delivery system for delivering a steady flow of sublimated vapor 50 to a vacuum chamber 130 comprises a vaporizer 28 of a solid material 29, a mechanical throttle valve 100, a pressure gauge 60, and a vapor conduit 32 to the vacuum chamber. A vapor flow rate is determined by both the temperature of the vaporizer and the setting of the conductance of the mechanical throttle valve located between the vaporizer and the vacuum chamber. Temperature of the vaporizer is determined at a set-point temperature by closed-loop control 35. The mechanical throttle valve is electrically controlled, and a valve position is controlled by a closed loop 120 of an output of the pressure gauge. A vapor flow rate can be generally proportional to the pressure gauge output. All surfaces 37 exposed to the vapor from the vaporizer to the vacuum chamber are heated to prevent condensation. A gate valve and a rotation type butterfly valve can act as a throttle valve. COPYRIGHT: (C)2010,JPO&INPIT