XHV Gauge Head - 3B Gauge

Measurable as low as 10-12Pa (10-14mbar)

  • ♦ Reduction of soft X-ray & ESD by Bent Belt-Beam method.
  • ♦ Full-closed cylindrical cage-grid with an axial-slit.
  • ♦ Low outgassing hot-cathode gauge by using 0.2% BeCu alloy body.

3B Gauge without deflector cover

3B Gauge principle

3B Gauge without deflector cover

What is Bent Belt-Beam (BBB) Gauge ?

3BG-03 is a commercially extreme-high vacuum hot-cathode ionization gauge head that can measure pressures as low as 5.4e–12 Pa (5.4e-14 mbar), by reducing the limits imposed by soft x-rays, electron-stimulated desorption (ESD), and outgassing. The gauge construction includes a cylindrical grid, which is closed at both ends; ions are drawn from the grid through a long, axial slit made in the cylindrical surface. Thus, the ion beam that emerges forms a "belt". This belt-like ion beam is guided on a curved path by a cylindrical sector deflector and terminates on a plate collector arranged after a beam trajectory rotation of 240°. These elements are embedded in a solid cylinder of 0.2% BeCu alloy, which has a low emissivity (radiation factor) and high thermal conductivity. As a result, the effects of heat radiation and outgassing (caused by the hot-cathode filament) and soft x-ray photoemission (the grid is the soft x- ray source) are reduced in the deflector/collector region. This electrode arrangement can also greatly decrease the flux of soft x-rays and ESD in the direction of the belt ion beam because it sets to 90° the angle between the extracted gas-phase ion beam and the maximum flux of soft x-rays and ESD. In addition, it achieves an extremely low pressure measurement limit by minimizing loss in the ion transport, and because the collector is well hidden, being located after the large deflection of the ion beam.

Operational parameters & data

Electron energy 120eV (standard)
Filament potential 100V (standard)
Filament power 2V x 1.5A of 1.6mA
Deflector bias 155V (between 1~4mA)
Degas Electron Bombardment (450V x 10~45mA)
Bakeout temperature 280°C max. without cable
Size DN40CF (1.1kg)
Connector BNC & 8 pin burndy-j
Sensitivity factor 5~8 x 10-2/Pa (at 1~4mA)
X-ray limit < 5 x 10-14 mbar
3BG can be operated with Prevac MG15 or Leybold IM540.

3B Gauge Deflector & Collector3B gauge cross section