Residual Gas Analyzer Size Comparison


The Extorr RGA has the smallest footprint outside your vacuum system

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Compare to 5 other brands (call 1-800-290-7891 or 1-724-337-3000 or email Extorr for names)


It is no surprise that the digital circuitry in the XTx00 residual gas analyzer can be made small with the latest high density integration and surface mount techniques. But the principle of operation of the quadrupole mass analyzer requires a considerable Radio Frequency Power. At 300 amu there is 1660 volts P-P at 2.304 MHz between adjacent poles of the mass filter. A very careful design of the RF. generator has resulted in a very efficient circuit with little wasted heat. The advantages of this are:

  • The electrical components can be packed denser for a smaller overall package.
  • No fan is required, an important consideration for clean rooms and general reliability. Fans cause noise, vibration, fail frequently and cause dust and dirt to accumulate in high voltage equipment.
  • Less power is wasted and a smaller power supply is sufficient.

Note that some manufacturers RGA Probes cannot be fully inserted into the vacuum system without extra plumbing or adapters.

What About the miniature probes that some manufacturers sell?

They were quite the rage several years ago, they promised operation to higher pressures because of their small size and a smaller intrusion into the vacuum system. The probes certainly are smaller, but poor sensitivity, poor resolution and greater susceptibility to contamination are the pitfalls of scaling to smaller sizes. However, there is a small pressure range where they have a more linear, though much lower output with respect to pressure changes. As for the high pressure cutoff, glow discharge between the quadrupole rods is the main limit to high pressure operation, not the mean free path length of the residual gas molecules, so they have roughly the same high pressure operating limit. Operation at high pressures will result in a very short filament life also. We intend to publish results of a side by side comparison with one of these in the near future.