JPH056798A - Rf power supply device for icp - Google Patents

Abstract

PURPOSE:To miniaturize a device by directly connecting a power summing part to a matching part, and receiving them in a matching device. CONSTITUTION:A RF signal transmitted from an oscillator 1 is divided by a power divider 3 and then transmitted to first and second power amplifiers 4a, 4b, respectively. The RF power amplified by the amplifier 4a, 4b is sent to, for example, a matching device 6 of impedance 50OMEGA. Therefore, the output impedance of a synthesizer 6 is, for example, 25OMEGA, and the output power is 1/(root 2) according to the equation of W=V<2>/R when the passed voltage is equal. Thus, the voltage resistance of a parallel capacitor 622 is 1/(route 2) in the case of the matching device of impedance 5OMEGA, allowing the miniaturization. Since a power summing part 61 and a matching part 62 are directly connected to each other and received in a matching device 6, a circuit for converting the output impedance of the summing part 61 is not required. The withstand voltage of the matching device 61 is also reduced.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a high frequency inductively coupled plasma (hereinafter referred to as "ICP") RF power supply device,
More specifically, the present invention relates to a small-sized RF power supply device for ICP which is mounted on an ICP analysis device and does not require impedance conversion after power combination and can lower the withstand voltage of a capacitor of a matching device.

[0002]

2. Description of the Related Art A high-frequency inductively coupled plasma analyzer using a quadrupole mass spectrometer generally supplies argon gas from an argon gas supply source to the outer chamber and outermost chamber of a plasma torch via a gas regulator. The sample (analysis target) is supplied to the inner chamber from the sample introduction device. Also,
A high-frequency current is applied to the high-frequency induction coil wound around the plasma torch by a high-frequency power source, and a high-frequency magnetic field is formed around the coil. In this state, when electrons or ions are implanted in the argon gas in the vicinity of the high frequency magnetic field, high frequency inductively coupled plasma is instantaneously generated by the action of the high frequency magnetic field.

Further, the inside of the fore chamber main body sandwiched between the nozzle and the skimmer is sucked by a vacuum pump. Further, the center chamber is provided with an extraction electrode, an aperture lens, a quadrupole lens, an aperture, and an entrance lens, and the inside of the center chamber is a first oil diffusion pump. Rear chamber, which is aspirated by and contains a quadrupole mass filter
The inside is sucked by the second oil diffusion pump.

In this state, the sample vaporized as described above is introduced into the high frequency inductively coupled plasma, and ionization and light emission are performed. Ions in the plasma are converged through the extraction electrode and the ion lens system after passing through a nozzle and a skimmer, and are introduced into the quadrupole mass filter.

Of the ions thus entered into the quadrupole mass filter, only the ions having the desired mass-to-charge ratio pass through the quadrupole mass filter and are guided to the secondary electron multiplier to be detected. This detection signal is sent to the signal processing unit for calculation /
By processing, the elemental analysis value of the measured element in the sample can be obtained. Also, the ICP power source is 27.12 MHz or 40.68 MHz and 1.6 to
It is common to output 2.0 kW.

[0006]

However, in the above-mentioned conventional example, in the case of the vacuum tube, this output can be obtained by one vacuum tube, but in the case of the semiconductor amplifier, the above output can be obtained by a single module. Was difficult. Therefore, the outputs of a plurality of modules are combined to obtain the above-mentioned output, and there is a drawback that the division and combination of electric power are required and the configuration is complicated. In addition, the size of the matching unit needs to have the same capacity (size) for the same power regardless of whether it is a vacuum tube or a semiconductor, and as a result, it is difficult to downsize the RF power supply device.

The present invention has been made in view of such a situation, and its problem is a small-sized I which does not require impedance conversion after power combination and has a low withstand voltage of a matching device capacitor.
An object is to provide an RF power supply device for CP.

[0008]

The present invention is an R for ICP.
In the F power supply device, a power synthesizing unit for transmitting the electric power sent from the first power amplifier via the first transmission line and the electric power sent from the second power amplifier via the second transmission line, in parallel The above problem is solved by directly connecting a capacitor and a matching section having a series capacitor and providing them inside a matching unit.

[0009]

The present invention operates as follows. That is, the RF signal sent from the oscillator is amplified by the preamplifier,
It is divided by the power divider and sent to the first and second power amplifiers, respectively. Since the RF power amplified by each power amplifier enters the power combiner, its output impedance becomes small. Therefore, the withstand voltage of the parallel capacitor is also reduced and the size can be reduced. In addition, since the power combiner and the matching unit are directly connected and housed in the matching unit, there is no need to pass a transmission path between the power combiner and the matching unit, and the output impedance of the power combiner is converted. The circuit to operate is also unnecessary.

[0010]

The present invention will be described in detail below with reference to the drawings. FIG. 1 is a block circuit diagram of an embodiment of the present invention, in which 1 is an oscillator for oscillating and generating an RF (high frequency) source,
2 is a pre-stage amplifier, 3 is a power divider, 4a and 4b are power
Amplifiers 5a and 5b are transmission lines, 6 is a matching unit, 61 is a power combining unit, 62 is a matching unit, 621 is a series capacitor, 6
22 is a parallel capacitor, and 7 is a work coil.

In the embodiment of the present invention having such a block circuit, the RF signal transmitted from the oscillator 1 is
After being amplified by the preamplifier 2, it is divided by the power divider 3 and sent to the first and second power amplifiers 4a and 4b, respectively.

The RF power amplified by the power amplifiers 4a and 4b is, for example, a matching device 6 having an impedance of 50Ω.
to go into. Therefore, the output impedance of the combiner 6 is, for example, 25Ω, and the output voltage is W when the passing voltage is the same.
= V ² / R wherein, according to an / the (Le - DOO 2) become. Therefore, the withstand voltage of the parallel capacitor 622 is the impedance 5
It becomes 1 / (route 2) of the case of a 0 Ω matching box, and the size can be reduced.

Further, since the power combiner 61 and the matching unit 62 are directly connected and housed in the matching unit 6, there is no need to pass a transmission path between the power combiner 61 and the matching unit 62. Therefore, a circuit for converting the output impedance of the power combiner 61 from 25Ω to 50Ω is also unnecessary. The present invention is not limited to the above-mentioned embodiment, and various modifications can be made.

[0014]

According to the present invention as described in detail above, in the RF power supply device for ICP, the electric power sent from the first power amplifier through the first transmission line and the second power amplifier from the second power amplifier are transmitted. The power combiner, to which the power sent through the transmission line is sent, and the matching part having a parallel capacitor and a series capacitor are directly connected to each other and are provided inside the matching device.

As described above, since the power combiner and the matching part are directly connected and housed in the matching box, a circuit for converting the output impedance of the power combiner is not required. Also, the withstand voltage of the matching device is reduced. Therefore, according to the present invention, it is possible to realize a small-sized ICP RF power supply device that does not require impedance conversion after power combination and can reduce the capacitor withstand voltage of the matching unit.

[Brief description of drawings]

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

[Explanation of symbols]

 1 Oscillator 2 Pre-amplifier 3 Power divider 4a, 4b Power amplifier 5a, 5b Transmission line 6 Matching device 61 Power combiner 62 Matching part 7 Work coil

Claims (1)

Claim: What is claimed is: 1. In an ICP RF power supply device, the power sent from a first power amplifier via a first transmission line and the power sent from a second power amplifier via a second transmission line. An RF power supply device for ICP, characterized in that a power combining unit for transmitting the generated power and a matching unit having a parallel capacitor and a series capacitor are directly connected to each other and provided inside the matching unit.