Function and design
PlasmaQuant 9100 (Elite)
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Figure 1 Emission spectrometer, with opened plasma compartment
3.2.1
Plasma generation
HF generator
The emission spectrometer uses a free-running HF generator (high-frequency genera-
tor) with a frequency of 40.68 MHz. With the help of the high performance coil, the HF
generator has an output of 700 to 1700 W into the plasma. The fully automatic adjust-
ment of the power relative to the actual current sample load in the plasma provides high
plasma consistency. This makes the plasma very robust and able to manage difficult
sample matrices such as organic solutions or salt loads. The HF generator is located im-
mediately behind the plasma compartment and is shielded separately because of the
high intensity of high frequencies.
The power for maintaining the plasma is transferred to the torch in the plasma compart-
ment by means of an induction coil with four windings. The induction coil is water-
cooled.
During the initial plasma ignition period, a high voltage spark is passed from the ignition
spark generator to the discharge spring in the high-frequency field in the torch. The dis-
charge spring is located near the induction coil.
Torch
The torch is designed with three layers and consists of an outer tube, an inner tube and
the injector tube on the inside.
The outer tube, in conjunction with the bonnet inserted into the coil, electrically insu-
lates the plasma from the induction coil and shields the plasma from the ambient air.
The plasma gas flows between the outer and inner tube. This gas is ionized at the induc-
tion coil and converted to a plasma state. The tangential flow of the plasma gas into the
space between the outer and inner tube cools the outer tube and prevents it from melt-
ing due to the high plasma temperatures.
The auxiliary gas flows in the intermediate space between the inner tube and the injec-
tor. It pushes the aerosol of the sample solution away from the injector.
The injector has the task of injecting the sample aerosol into the plasma. The measure-
ment solution is transported by the nebulizer gas from the spray chamber through the
injector into the plasma.