JPH0589824A - High frequency induction coupling plasma mass-spectrometer - Google Patents

Abstract

PURPOSE:To provide a high frequency induction coupling plasma mass- spectrometer having a plasma power supply, with which the reflected waves are made smaller and the plasma electric power can be supplied effectively. CONSTITUTION:A phase sensor 26 drives a servo motor 28 so that the phase becomes a constant value PHI. A second variable capacitor VC2 is adjusted by this servo motor 28, and a power sensor 23 drives a pulse motor 27 so that the reflected wave power is minimized, and a first variable capacitor VC1 is adjusted with this pulse motor 27.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention excites a sample by using a high frequency inductively coupled plasma to generate ions, which are then introduced into a mass spectrometer through an interface and detected to detect the sample in the sample. More specifically, the present invention relates to a high frequency inductively coupled plasma mass spectrometer for analyzing elements, and more specifically, a variable capacitor connected in parallel in a matching circuit of a plasma power supply monitors a reflected wave and automatically adjusts the plasma so that the reflected wave is minimized. The present invention relates to a high frequency inductively coupled plasma mass spectrometer to which plasma power is efficiently supplied from a power source.

[0002]

2. Description of the Related Art A high frequency inductively coupled plasma mass spectrometer is generally constructed as shown in FIG. That is, in FIG. 2, the outer chamber 1b and the outermost chamber 1c of the plasma torch 1 are shown.
Argon gas is supplied from the argon gas supply source 3 via the gas regulator 2 to the inner chamber 1a, and the solid sample in the sample introduction device 4 is vaporized by the laser light emitted from the laser light source 5. After that, the carrier gas is carried in by argon gas.

When the sample is a liquid, the sample introduction device 4
The laser light source 5 is removed, and a nebulizer for atomizing the introduced liquid sample and supplying it to the inner chamber 1a of the plasma torch 1 is attached. Also, the sample is often a liquid rather than a solid.

On the other hand, a high frequency current is applied to the high frequency induction coil 6 wound around the plasma torch 1 by a plasma power source 10, and a high frequency magnetic field (not shown) is formed around the coil 6. In this state, when electrons or ions are implanted in the argon gas near the high frequency magnetic field,
A high frequency inductively coupled plasma 7 is instantaneously generated by the action of the high frequency magnetic field. The inside of the fore chamber main body 11 sandwiched between the nozzle 8 and the skimmer 9 is, for example, 1 Torr. Have been sucked into.

Further, ion lenses 14a and 14b are provided in the center chamber 13, and the inside of the center chamber 13 is, for example, 10 ^-5 Torr. The interior of the rear chamber 17 which is sucked into the chamber and accommodates the mass filter (for example, a quadrupole mass filter) 16 is, for example, 10
^-5 Torr. Have been sucked into.

In this state, the sample vaporized as described above is introduced into the high frequency inductively coupled plasma 7, and ionization and light emission are performed. Ions in the plasma 7 pass through a nozzle 8, a skimmer 9 and an extraction electrode, and then an ion lens (or doublet quadrupole lens) 14
It is converged after passing between a and 14b, and then, is guided to the secondary electron multiplier 19 through the mass filter 16 and detected. This detection signal is sent to the signal processing unit 20 for calculation /
By processing, the elemental analysis value of the measured element in the sample can be obtained.

On the other hand, the output of the plasma power source 10 is adapted to be supplied to the high frequency induction coil 6 after being matched by a matching circuit (not shown). Further, the matching circuit is adapted to be matched by a variable capacitor connected in series and a variable capacitor connected in parallel.

[0008]

By the way, in the above conventional example, the phase is detected by the variable capacitors connected in series in the matching circuit, and the phase is automatically changed so as to become zero. It was However, the variable capacitor connected in parallel in the matching circuit has been set by the user from an external workstation. Therefore,
It has not always been operating at its best efficiency, ie with the minimum of reflected waves.

The present invention has been made in view of the above circumstances, and an object thereof is to provide a high frequency inductively coupled plasma mass spectrometer having a plasma power source capable of reducing reflected waves and efficiently supplying plasma power. Especially.

[0010]

SUMMARY OF THE INVENTION The present invention provides a high frequency inductively coupled plasma mass spectrometer, a driver, a power amplifier for amplifying the output of the driver, and a traveling wave received by the output of the power amplifier. And a power detector for detecting a reflected wave, a matching circuit having a first variable capacitor connected in parallel, a second capacitor connected in series, and a phase detector, and a reflected wave output of the power detector. A pulse motor that adjusts the first variable capacitor and a servo motor that receives the output of the phase detector and adjusts the second variable capacitor form a plasma power supply, and the phase detector has a constant phase Φ. Driving the servo motor, the second variable capacitor is adjusted by the servo motor, and the power detector drives the pulse motor so that the reflected wave power is minimized. , The pal Mode - is obtained by solving the above problems by configuring so as to adjust said first variable capacitor by capacitor.

[0011]

The present invention operates as follows. That is, the phase detector drives the servo motor so that the phase becomes Φ, and the servo motor adjusts the second variable capacitor.
Further, the power detector receives the output of the power amplifier and drives the pulse motor so that the reflected wave power becomes the minimum, and the pulse motor adjusts the first variable capacitor.

[0012]

The present invention will be described in detail below with reference to the drawings. FIG. 1 is a block circuit diagram of an essential part of an embodiment of the present invention showing the structure of the plasma power source 10 and the like. In the figure, 21 is a driver for outputting an output of 0 to 80 W and 27.12 MHz, and 22 is a driver-1. 2k after receiving the output of
1 is a power amplifier that amplifies to W, 23 is a power detector that receives the output of the power amplifier 2 and detects, for example, a traveling wave and a reflected wave that are reduced to 1/100, 24 is a matching circuit, and 25 is a matching circuit.
Of the load coil corresponding to the high frequency induction coil 6 of FIG. Reference numeral 28 is a servo motor that receives the output of the phase detector 26 and adjusts the second variable capacitor VC2 in the matching circuit 24.

In the embodiment of the present invention having such a main block circuit, the phase detector 26 drives the servo motor 28 so that the phase becomes Φ, and the servo motor 28 drives the second The variable capacitor VC2 is adjusted. That is, the second variable capacitor VC2 is automatically operated by the phase detector 26 via the servo motor 28 so that the phase becomes zero.

Further, the power detector 23 is the power amplifier 2
The reflected wave is detected by receiving the output of 2 and the pulse motor 27 is driven so that the reflected wave power is minimized, and the first variable capacitor VC1 is adjusted by the pulse motor. That is, while monitoring the reflected wave, the first variable capacitor VC1 is also automatically changed by the power detector 23 via the pulse motor 27 so that the reflected wave is minimized.

With respect to this, in the above-mentioned conventional example,
The user inputs a signal to the workstation provided outside the plasma power supply so that the reflected wave is minimized, and the pulse motor is driven by the instruction of this workstation to drive the first variable capacitor. Was being adjusted. Therefore, as described above, the optimum efficiency, that is, the reflected wave is not always operating in the minimum state. However, according to the present invention as described above, it is possible to prevent the workstation from being operated by the user. The best efficiency, that is, reflection Will always work with minimal waves.

[0016]

According to the present invention described in detail above, since the first and second variable capacitors are all automatically operated in the matching circuit, the plasma power supply can be efficiently driven. There is. Therefore, according to the present invention, a high frequency inductively coupled plasma mass spectrometer having a plasma power source capable of efficiently supplying plasma power by reducing reflected waves is realized.

[Brief description of drawings]

FIG. 1 is a block circuit diagram of an essential part of an embodiment of the present invention.

FIG. 2 is a general configuration explanatory view of a high frequency inductively coupled plasma mass spectrometer.

[Explanation of symbols]

 1 Plasma torch 7 High frequency inductively coupled plasma 21 Driver 22 Power amplifier 23 Power detector 24 Matching circuit 25 Load coil 26 Phase detector 27 Pulse motor 28 Servo motor

Claims (1)

[Claims] 1. In a high frequency inductively coupled plasma mass spectrometer, a driver, a power amplifier for amplifying an output of the driver, and a power for receiving a traveling wave and a reflected wave by receiving an output of the power amplifier. A matching circuit having a detector, a first variable capacitor connected in parallel, a second capacitor connected in series, and a phase detector, and adjusting the first variable capacitor by receiving the output of the reflected wave of the power detector. Pulse motor and a servo motor that receives the output of the phase detector and adjusts the second variable capacitor form a plasma power supply, and the phase detector maintains the phase at a constant value Φ. -The pump motor is driven, the second variable capacitor is adjusted by the servo motor, and the power detector drives the pulse motor so that the reflected wave power is minimized. - Inductively coupled plasma mass spectrometer, characterized in that said first variable capacitor is adjusted by.