2
Functional Description
Mass Spectrometer
30 TSQ Series Hardware Manual Thermo Scientific
Figure 26. Collision cell (top), Q2 quadrupole (bottom), and lenses
RF and DC Fields Applied to the Quadrupoles
In a quadrupole rod assembly, because rods opposite each other in the array connect
electrically, the four rods can be considered as two pairs of two rods each. Ac and dc voltages
are applied to the rods and these voltages are ramped during the scan. Voltages of the same
amplitude and sign are applied to the rods of each pair. However, the voltages applied to the
different rod pairs are equal in amplitude but opposite in sign. See Figure 27.
Figure 27. Polarity of the rf and dc voltages applied to the rods of the Q1 and Q3 mass analyzers
The ac voltage applied to the quadrupole rods is of constant frequency (1.123 MHz). The rf
voltage applied to the rods varies from 0 to 10000 V peak-to-peak, and the dc voltage varies
from 0 to ±840 V. Voltages of the same amplitude and sign are applied to each rod pair.
However, the voltages applied to the other rod pair are equal in amplitude but opposite in
sign.
Lenses L21,
L22, and L23
Lenses L31,
L32, and L33
RF voltage
+ dc voltage
RF voltage 180° out of phase
– dc voltage
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