Stanford Research O635RMS

The Stanford Research O635RMS is a residual gas analyzer (RGA) for real-time vacuum system diagnostics, leak detection, and gas composition analysis. It combines a compact quadrupole mass filter with selectable detection modes to resolve gas species from 1 to 300 amu with sub-amu resolution. The modular design separates the probe head from its control electronics, enabling independent bakeout procedures and simplified maintenance in demanding vacuum environments.

– Technical Specifications

• Mass range: 1 to 300 amu
• Mass resolution: Better than 0.5 amu at 10% peak height (AVS 2.3 standard); adjustable for constant peak width
• Faraday cup sensitivity: 2 × 10⁻⁴ A/Torr
• Electron multiplier sensitivity: <200 A/Torr (user adjustable across full high voltage range)
• Minimum detectable partial pressure (FC): 5 × 10⁻¹¹ Torr
• Minimum detectable partial pressure (EM): 5 × 10⁻¹⁴ Torr
• Detection limit: 5 × 10⁻¹⁴ Torr
• Maximum probe operating temperature: 70 °C

– Key Features

• Dual thoriated-iridium (ThO₂/Ir) long-life filaments for extended emission capability
• User-replaceable filament assembly (minutes to swap)
• Standard Faraday cup detection with optional continuous dynode electron multiplier
• Probe mounts on standard 2.75" Conflat® flange with minimal outgassing design
• Ionizer clearance requirement: ~2.5" (comparable to standard ion gauge)
• Self-aligning components enable rapid reassembly after cleaning
• Electronics control unit (ECU) operates on +24 VDC @ 2.5 A external supply or optional AC-powered internal module
• Status LEDs for electron multiplier, filament, electronics, and probe health
• Real-time Windows software with analog and histogram mass scan modes
• Analog mode displays partial pressure vs. mass number; strip chart mode shows pressure vs. time
• Built-in leak detection capability and probe parameter control
• ASCII export for spreadsheet integration; META or clipboard graphics output
• Password-protected head parameter locking

– Interfaces & Integration

• USB, RS-232, Ethernet connectivity
• Integrated analog I/O, relay, and GPIO ports for external system control