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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 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 Downloads
Product Downloads
Below is a list of available file downloads for this product.
KJLC 909AR Series Manual
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Gauge Selection Guide
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Gauges FAQ
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