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KJLC® 909AR Series Ion Gauge

Note KJLC no longer offers the 909AR hot filament gauge. Please consider the 354 gauge/controller as a possible alternative and feel free to contact the KJLC product team at gauging@lesker.com with any additional questions.

Our new series features hot filament transducers with integrated electronics.

These hot filament sensors are Bayard-Alpert style, utilizing a fine wire collector at the center of a grid. Due to its small area, few x-rays hit the collector; therefore, the gauge can measure very low pressures. These transducers include two yttria-coated iridium filaments for reduced downtime. Yttria-coated iridium is resistant to damage caused by high oxygen partial pressures and exposure to atmosphere. The tube operates at lower temperatures, giving a lower chemical reaction rate and minimizing thermal interference. The 909AR includes a screen to shield it from large particles.


  • Ideal measurement tools for high-vacuum applications, including pressure measurement of high-vacuum chambers and control or start-up of high-vacuum systems
  • Measures base pressure and the pressure of back-filled gases
  • Use in semiconductor processing and analytical systems


  • Wide measurement range of 10-10 to 10-2 Torr (mbar) for high-vacuum process monitoring
  • Pressure-controlled e-beam degas for automated degas without filament shut down, patent pending
  • Low-cost transducer alternative
  • Compact design with integrated electronics and sensor in one unit
  • Two-filament design for extended life
  • Ease of operation with both analog and RS-232 digital communication
  • Simultaneous pressure measurement during degas cycle
  • Sensor portion of transducer can be replaced
  • Process control set-point relay
  • UHV-compatible materials used in sensor
  • Reliable and repeatable pressure measurement for process stability
  • CE marked, compliant with EMC Directive 89/336/EEC and Low Voltage Directive 73/23/EEC

Specifications Table

Measurement Range3 x 10-10 to 5 x 10-2 Torr (4 x 10-10 to 6.5 x 10-2 mbar)
Communications InterfaceRS-232
Accuracy (% of measurement)±20% of Reading (typical)
Temperature (operating)0-40° C
Materials Exposed to Vacuum304 stainless steel, glass, tungsten, platinum-clad molybdenum, yttria-coated iridium (filament)
Repeatability (Typical)Approximately 5% of Reading
Set-Point Range5 x 10-10 to 9.5 x 10-3 Torr (6.5 x 10-10 to 1.2 x 10-3 mbar)
Set-Point Relays1, SPDT, 1 A@ 30VAC/VDC (resistive)
Calibration GasAir/Nitrogen
Analog Outputs0-10 VDC, 1 volt/decade, semilogarithmic
Power Supply Requirements24 VDC, 15 W
Internal Volume23 cm3
Response Time100 ms
Ion Gauge TypeBayard Alpert
Ion Gauge TubesDegas: Electron beam (3 W)

Product Manual
For a download of the product manual, click here.
Contact Us
To speak with someone directly, please call 1-412-387-9200 or email international@lesker.com.