RGA Capabilities

RGA Measurements

• RGA (Residual Gas Analysis) is a measurement technique which can be used to determine the vacuum cleanliness of parts.
• Parts are placed inside a high vacuum chamber (< 10-6 mbar). Contamination (for example oil and grease) is released from the part due to the high vacuum condition.
• The composition of the remaining gas molecules and atoms in the chamber, also containing the molecules released from the part is determined with the RGA.

Background Subtraction

• We measure on regular basis the outgassing values of the empty system, to determine the background values of the chamber.
• When we insert the part in the chamber and perform the RGA measurement. We measure the combined outgassing of the system (background) and the inserted part.
• After the measurement we will subtract the background values from the results of the measurement with the part.
• This gives us the net outgassing of the part.

RGA - XXL

• Envelope: 2000 x 2000 x 1000 mm
  (l x w x h)
• Max Weight: 2000 kg
• Bake-out temperature: 200 ºC
• Metal sealed vacuum chamber with differential pumped double O-ring sealed door for low background values
• System installed in ISO 6 Cleanroom

RGA - S

• Envelope: Ø 200 x 400 mm
  (diameter and horizontal length)
• Max Weight: 45 kg
• Bake-out temperature: 200 ºC
• Low background pressure

• Fully metal sealed vacuum chamber.
• Selectable pumping speed to optimize the signal to noise ratio for each product.

Ion Source

• Molecules and atoms enter the ion source by random chance.
• In the ion source a filament creates free electrons which are accelerated through the ion source and can collide with the there present molecules and atoms.
• When an electron collides with a molecule an electron is shot out of molecules orbit resulting in a positive charged ion.
• This ion can be steered by means of electrostatic fields.
• All ions are guided by the ion optics into a a straight beam that is fed into the quadrupole mass filter.

Quadrupole Mass Filter

• When the ions enter the Quadrupole mass filter they travel between four rods.
• These 4 rods are 2 pairs of 2 rods which form a low and a high pass filter, and there fore combined creating a band pass filter.
• A changing electromagnetic (RF) field on the two rod pairs brings one mass-over-charge ratio in resonance and will reject all other mass-charge-ratios.
• By changing the frequency of the electromagnetic field different masses can be brought in resonance and be passed through the filter.

Electron Multiplier

• When the resonant ions exit the quadrupole, they are transported into the (Secondary) electron multiplier (SEM).
• This is a trumpet-shaped tube with a special coating on the inside.
• A high voltage is placed over the SEM to accelerate the ions into the SEM.
• When the ion enters the SEM and collides with the wall it will release multiple electrons.
• These electrons will in turn also collide with the wall of the SEM and create again more electrons.

Pico Ampere meter

• The electrons exiting the electron multiplier are fed into a pico ampere meter.
• The number of electrons per unit of time represents the partial pressure of the mass-over-charge-ratio selected by the quadrupole mass filter.
• Measuring the current provides a relative measurement of the amount of mass present in the selected ratio.
• By scanning a complete mass-range, the relative contents of the individual masses can be determined.
• This creates the typical bar-graph spectrum of the RGA measurement report.