26 MASS SPECTROMETERS AND SPECTOGRAPHS AND COMPONENTS AND RECORDING SYSTEMS THEREFOR; VOLTAGE, CURRENT, POWER AND TEMPERATURE REGULATORS FOR SCIENTIFIC APPLIANCES; ELECTRICAL PROTECTION CIRCUITS FOR PREVENTION OF FAILURE AND DAMAGE TO SYSTEM COMPONENTS AND INSTRUMENTATION CIRCUITRY CONTROLS INCLUDING: SOURCE CONTROLS, ION BEAM SOURCE CONTROLS, ION GAUGE CONTROLS, THERMOCOUPLE GAUGE CONTROLS; ELECTRICAL CONTROL AND SIGNAL PANELS FOR TURNING INSTRUMENTATION SYSTEMS OFF AND ON AND DISPLAYING OPERATIONAL STATUS THEREOF; ELECTRICALLY CONTROLLED AUTOMATIC REFILL SYSTEMS FOR LIQUID NITROGEN COOLANT SYSTEMS; MEASURING METERS; RESIDUAL GAS ANALYZERS; PARTIAL PRESSURE ANALYZERS; ISOTOPE SEPARATORS; TEMPERATURE REGULATOR CONTROLS; RESOLVING POWER MULTIPLIERS; RESPIRATORY GAS ANALYZERS; ION CURRENT DETECTORS; ELECTRON MULTIPLIERS; ELECTRON MULTIPLIER POWER SUPPLIES; GAS DETECTORS; AND PARTS AND ACCESSORIES