JPH02231552A - Plasma spectroscopic analysis device - Google Patents

Abstract

PURPOSE:To improve the performance to analyze trace components by radiating electromagnetic waves to a gaseous sample which passes the magnetic field in a test tube to generate electron cyclotron resonance and to convert the gaseous sample to plasma and analyzing the wavelength emitted by plasma. CONSTITUTION:The gaseous sample arrives at the neighborhood of the central part of the test tube 1 and microwaves are radiated by an antenna 3 in this part. A magnet 2 is disposed on the outer periphery near the antenna 3 to generate the magnetic field in the tube 1 and to induce the electron cyclotron resonance. The free electrons in the dilute gas in the magnetic field makes cyclotron motion around the magnetic lines of force but the energy is resonantly absorbed and accelerated by making the electromagnetic waves of the coincident frequency incident thereon. The accelerated free electrons collide against the atoms in the dilute gas and spring off the electrons in the atoms, thereby ionizing the atoms and generating the plasma. The ions in the plasma capture the electrons gain and return neutral but the light having the wavelength specific to the atoms, radicals and molecules constituting these ions is radiated at this time. The components of the sample are thereby known.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a plasma spectrometer that generates luminescent plasma and performs spectroscopic analysis of trace gases.

[Prior Art] A plasma spectrometer is a device that analyzes the components of a gas sample by generating plasma in a gas sample and detecting the light generated by the plasma with a light wavelength analyzer. Seed devices include those shown in Figures 2 and 3. Figures 2 and 3 are diagrams for explaining the principle configuration of a conventional plasma spectrometer, respectively.
) is a sample tube that introduces the gas that is the measurement sample, and is made of, for example, quartz glass. (5) is the generated plasma, (
6》 is the direction of the detected light ray coming out of the plasma (5),
(7) is a light wavelength analyzer, (10) is a sample inlet, (1
1) is the 21 dollar valve, (12》 is the sample outlet, (14)
) is a coil for high-frequency discharge, and (15) is a waveguide or resonant cavity for guiding microwaves.

Next, the operation will be explained. Figure 2. The plasma spectrometer shown in Fig. 3 is a device that generates plasma using high-frequency discharge or microwave discharge, and a gas sample for analysis is introduced through the sample inlet (10), and the sample is Contain in tube (1) or sample tube (1)
) and installed outside the coil (14). A device such as a waveguide or a resonant cavity (15) causes a high frequency or microwave discharge, i.e. the high frequency or microwave energy generated by an external device is absorbed into the gas sample inside the sample tube (1). to generate plasma (5), and the light beam (6) emitted by this plasma (5) is analyzed using a light wavelength analyzer (7) to analyze the components of the gas sample. The operating region where this occurs is 1 to 10-3To in terms of gas pressure.
rr is required, and the generated plasma density is 1
It is about 010 to 1011 pieces/cm3. Each valve (11) is used to adjust the pressure of the gas inside the sample tube (1), and in the device shown in FIG. 2 it is a coil (14), and in the device shown in FIG. High frequency waves or microwaves are introduced using a wave tube or resonant cavity (15). After the component analysis, the gas is discharged from the sample outlet (12). [Problems to be Solved by the Invention] The conventional plasma spectrometer described above is configured as described above, but it is possible to further improve the analysis performance, enable analysis of trace components, and use a plasma spectrometer with strong molecular bonding force. There was a desire to develop a device that could also analyze gas components. This invention was made to solve these problems, and provides a plasma spectrometer that can analyze trace components, expand the range of gas components that can be analyzed, and perform accurate analysis. is intended to provide.

[Means for Solving the Problems] In the plasma spectrometer according to the present invention, a magnet is disposed around the outer periphery of the sample tube near the antenna that radiates microwaves, and a magnetic field is generated inside the sample tube.

[Operation] In this invention, a magnet is disposed around the sample tube near the antenna that emits microwaves, and a magnetic field is generated inside the sample tube, so the operating pressure can be adjusted using electron cyclotron resonance. It becomes possible to lower the plasma temperature and increase the plasma temperature of the generated plasma, thereby increasing the plasma density.

[Examples] Examples of the present invention will be described below with reference to the drawings. 1st
The figure is a sectional view showing an embodiment of a plasma spectrometer according to the present invention. In the figure, the same reference numerals as in FIGS. 2 and 3 indicate the same or corresponding parts, (2) is a magnet, (3)
is an antenna for microwave radiation, (4) is a coaxial cable that guides microwaves, (8) is a vacuum chamber, (9) is an exhaust device, and (13) is a microwave oscillator. Next, we will explain the operation. Gas sample is at the valve (11)
The antenna (3) passes through the sample inlet (10), passes through the sample tube (1), and reaches near the center of the sample tube (1).
Microwaves are emitted by the Also, this antenna (3
) A magnet (2) is placed around the outer periphery of the sample tube (1), which has a structure that generates a magnetic field of a predetermined strength inside the sample tube (1) to cause electron cyclotron resonance. ing. A plasma generation method using electron cyclotron resonance has been established as an ion source technology, and this technology is also applied in principle to the plasma spectrometer of the present invention.

In other words, in a magnetic field, free electrons in a dilute gas perform a rotational motion called cyclotron motion around the magnetic field lines, and when electromagnetic waves of the same frequency are incident thereon, they absorb energy resonantly and accelerate. Accelerated free electrons collide with atoms in the dilute gas, knocking off the electrons within the atoms, ionizing the atoms, and generating plasma.

Ions in the plasma capture electrons again and return to neutrality, but at this time they emit light with a wavelength unique to the atoms, radicals, and molecules that make up the ions. Therefore, by measuring the wavelength of this light, it is possible to know the components of a gas sample, and it becomes possible to perform plasma spectroscopic analysis using an electron cyclotron. Note that, unlike the ion source technology described above, in a plasma spectrometer that uses electron cyclotron resonance,
In order to prevent impurities from entering the gas sample, the generated plasma (5) is transferred to a magnet (2), an antenna (3)
, a vacuum chamber (8), etc., must be separated from magnetic field generating means, electromagnetic wave emitting means, and vacuum means for generating plasma.

Therefore, in this invention, the magnetic field generating means and the electromagnetic wave emitting means are arranged outside the sample tube (1), and are completely separated from the plasma (5) generated inside the sample tube (1) across the sample tube wall. It is configured as follows.

In the plasma spectrometer according to the present invention that utilizes electron cyclotron resonance as described above, the operating pressure at which plasma is generated is 10-3 to 1
The generated plasma density is as low as 0-'Torr and 101
The applicant's experimental results have shown that the number of plasma particles is large, ranging from 2 to 1013 particles/cm', and the plasma temperature is high. Each valve (11) is used to adjust the pressure of the gas in the sample tube (1), and the gas after component analysis is
It passes through a valve (11), is discharged from a sample discharge port (12), and is exhausted by an exhaust device (9).

In the above embodiment, the magnet (2) and the antenna (3)
) is installed in a vacuum chamber (8) with an exhaust device (9), but if the structure is such that plasma is not generated outside the sample tube (1), it can be separated from the exhaust device (9). It can be made into a structure. Also, as a magnet (2),
Both permanent magnets and electromagnets can be used. Furthermore, in the above embodiment, a coaxial cable (
4) and an antenna (3), a waveguide or a resonant cavity could also be used.

[Effect of the invention] As explained above, this invention utilizes electron cyclotron resonance by disposing a magnet around the sample tube near the antenna that radiates microwaves and generating a magnetic field inside the sample tube. Therefore, it is possible to lower the operating pressure, raise the plasma temperature of the generated plasma, and increase the plasma density, improving analytical performance and analyzing trace components, while minimizing the contamination of impurities. Accurate analysis can be performed, and since the plasma temperature is sufficiently high, it is possible to analyze gaseous components with strong molecular bonding forces that could not be analyzed conventionally.

[Brief explanation of the drawing]

FIG. 1 is a sectional view showing an embodiment of the present invention, and FIGS. 2 and 3 are diagrams showing the principle configuration of a conventional plasma spectrometer. (1) is sample tube, (2) is magnet, (3) is antenna, (4) is coaxial cable, (5》 is plasma, (6)
is the direction of the detected light beam, (7) is the optical wavelength analyzer, 8) is the vacuum chamber, (9) is the exhaust device, (10) is the sample inlet, (11) is the valve, and (12) is Sample outlet, (13
) is a microwave oscillator. Note that the same reference numerals in each figure indicate the same or corresponding parts. Figure 2 1: Sample tube 5: Plasma 6: Light beam direction 10: Sample inlet 11: Pulp 12: Sample outlet

Claims (1)

[Claims] A sample tube through which a gas sample for the purpose of analysis passes, an electromagnetic wave radiating means for radiating electromagnetic waves to the sample tube, and a magnetic field generating means for generating a magnetic field inside the sample tube by disposing a magnet around the outer periphery of the sample tube. , radiating electromagnetic waves by the electromagnetic wave emitting means to the gas sample passing through the magnetic field in the sample tube generated by the magnetic field generating means to generate electron cyclotron resonance, turning the gas sample into plasma, and changing the wavelength of light emitted by the plasma. A plasma spectrometer characterized in that a component analysis of the gas sample is performed by analysis.