Comprehensive controller for super sonic molecular beam GC-MS

Abstract

This paper presents a new, comprehensive digital circuit used for the control of a novel Gas Chromatograph Mass Spectrometer (GC-MS) interface that is based on Supersonic Molecular Beam (SMB). The circuit includes a Texas Instruments 150MHz digital signal controller (DSC), high voltage amplifiers for 8 independent channels and 4 independent channels of high resolution PWM. The circuit, along with a sophisticated embedded program and a custom made PC application, control all aspects of the interface: smart filament emission-current stabilization, static and scanning mass-dependent ion-source voltages, transfer-line heater PID controls with thermocouple feedbacks, on/off valves, relays and several peripheral device controls that enable the full operation of a turbo-molecular vacuum pump, and of gas flow and pressure controllers. All aspects of this comprehensive controller were successfully tested and it is already being used by several analytical chemists around the world for the control of the Aviv Analytical 5975-SMB GC-MS with Cold-EI.