Hardware manual

6-14 Agilent 7500 Series ICP-MS Hardware Manual

6 Technical Information

such as the position of the mach disc, that are affected by the plasma

temperature; a lighter mass penetrates through the skimmer cone easier than

a heavier mass.

Figure 131 Distribution of Ion Energy

Extraction Lens

This lens assembly is placed just behind the skimmer cone and mounted on

the skimmer base. Its purpose is to extract ions passed through the skimmer

cone and to accelerate them to the Einzel lens. Two lenses are driven at

negative voltage. After the skimmer cone, there are positive ions, electrons,

and neutral atoms. When the positive ions come close to the extraction lenses,

the ions are accelerated. On the other hand, electrons are repelled by the

extraction lenses and go to ground via the skimmer cone and the chamber

wall.

Since the extraction lenses are placed very close to the plasma, they can

become contaminated. When the signal response in the tuning mode is slow

after changing the lens voltage, the lens may have become dirty and cleaning

will be required.

Low

Ion Energy

High

Ion Lens Setting

Sensitivity