JPS5987800A - Method and device for generating jit plasma - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

Detailed Description of the Invention: More specifically, a method for stably generating a plasma jet by rotating a cathode point or an anode point formed at a cathode or anode by magnetic lines of force of a cylindrical magnet. Regarding equipment.

As is conventionally known, if the chance of collision between the electron flow and the gas is increased in some way)
A highly ionized gas, ie, plasma, is obtained at 7,000°C.

As shown in Fig. 1, the plasma generator usually has a rod-shaped electrode 1 in a cylinder A with an anode and a cathode.
3 is placed, arc discharge is performed between electrodes A and B, liquid or gas such as nitrogen, air, rare gas, etc. is injected from C and D to create a vortex flow, and the plasma generated by the arc discharge is turned into plasma. A plasma jet generator was used that emitted the jet from a small hole in the cathode or anode. .

The arc plasma thus created was cooled on the outside by the vortex and concentrated in the center, and furthermore, this concentrated plasma was focused by the electromagnetic bottle f-effect and heated to a high temperature.

By the way, among arc discharges, the TIG arc has extremely high stability, and uses a thin tungsten rod with a diameter of about 3 mm as the cathode and a water-cooled copper plate as the anode. An inert gas, such as argon, is used around the tungsten electrode.

The TIG arc has excellent stability because the electrode is protected with an inert gas, and the tungsten electrode used as the cathode only wears out at a rate of 10 m, 9 per 100 hours of operation.
On the other hand, it is said that there is no change at all in the copper electrode, which is the anode.

However, if a small amount of impurity is present in the inert gas used for discharge, the electrodes are severely consumed, resulting in extremely unstable discharge.

This is because when an active gas such as hydrogen or nitrogen is present in the inert gas, the arc contracts [2 and an anode bright spot is formed on the electrode, and this anode bright spot moves around the anode irregularly.
This is because the arc discharge becomes unstable and the copper electrode wears out, causing bright lines of copper to appear in the spectrum of the discharge.

Furthermore, when air (oxygen), water vapor, etc. are mixed in, the electrode wear becomes even more severe, and the discharge becomes extremely unstable.

On the other hand, if the plasma jet formed by a discharge also changes its position between the cathode and anode points due to gas pressure, impurities and wear and tear on the cathode or anode, the voltage and current will become unstable, and sometimes the discharge will stop. However, if the plasma jet is operated for a longer period of time, problems such as deformation of the area around the plasma jet emission hole may occur. A method has been proposed in which an auxiliary electrode as shown in FIG. 1E is inserted into a small hole for jet emission, and a cathode spot or an anode spot is formed on the auxiliary electrode to stabilize the jet.

According to this method, if the cathode spot or the anode spot uniformly covers the head of the auxiliary electrode, the cathode spot or the anode spot can be stabilized by sequentially replenishing the auxiliary electrode.8 However, many In some cases, only one side of the auxiliary electrode is severely worn out, resulting in pulsating voltage and current. .

Therefore, by replenishing the auxiliary electrode while rotating it slowly, the plasma jet was prevented from becoming unstable.

Unfortunately, in order to rotate the thin auxiliary electrode or push it out at a small speed, it is necessary to install many additional devices such as a motor drive, and the auxiliary electrode has a 5A to 50A1 and an electromagnetic pinch. In order to produce the effect, a large current of 100 to 200 A must be supplied, which means that the device itself becomes complex and large, occupying a large space, and is also extremely difficult to operate. It was not possible to avoid drawbacks such as:

Therefore, the present invention was made to eliminate such conventional drawbacks, and it is possible to stabilize the discharge and generate a plasma jet steadily, and the device has a simple structure.
Moreover, it has features such as being small, taking up little space, and being easy to operate.

That is, the method of generating a plasma jet of the present invention is a method of generating a plasma jet by arc discharge, in which a cathode point or an anode point is rotated circularly on a horizontal plane by the action of a magnetic field, and the cathode point or anode point is rotated in a circle on a horizontal plane. This feature is characterized in that an arc discharge is caused to occur between the anode point and the other anode point or d cathode point.

In addition, the plasma jet generator of the present invention has a ring-shaped magnet and a center of this ring-shaped magnet! It consists of a cylindrical discharge chamber that is centrally located and open at both ends, and a rod-shaped electrode is concentrically provided within the cylindrical discharge chamber at a distance from the inner circumferential wall of the cylindrical discharge chamber. The present invention is characterized in that plasma forming gas is supplied through a gap between the chamber and the rod-shaped electrode.

Hereinafter, the present invention will first be explained based on the drawings.

FIG. 2 shows an embodiment of the plasma jet generator according to the present invention, in which a cylindrical discharge chamber 1 with both ends open is provided concentrically at the center of an annular magnet 2, and Inside, a rod-shaped electrode 9 is inserted concentrically at a distance from the inner wall and extends downward from the middle of the cylindrical discharge chamber 1, and the lower end of the rod-shaped electrode 9 is Lower pole support part 10
Cooling water is supplied to this upper electrode support portion 10 to cool the rod-shaped electrode 9 . The annular magnet 2 is held between the upper and lower iron pieces 3" and 3.3' and supported by the support part 6. The lower iron piece 6' extends halfway along the rod-shaped electrode 9, and the upper iron piece 6 and the lower iron piece 6' A water cooling section 7 is formed between the two.

Cooling water is circulated through the water cooling section 7 (not shown), and the cylindrical discharge chamber 1 is strongly cooled when the discharge is continued for a long time.

Further, a circular magnetic field is formed around the inner circumferential wall 4 by the tips of the iron pieces 3' and 3''.Furthermore, below the lower iron piece 6' is a gas storage chamber for storing and mixing the gas that forms plasma. 5 is formed, and a gas introduction pipe 11 is attached to this gas storage chamber 5.

The annular magnet 2 is a donut-shaped permanent magnet, made of electromagnet or ferrite, and has magnetic properties such as a coercive force of about 2000.0 E%, a residual magnetic flux density of about 4.5 K Gauss, and a maximum energy product of about 4. ~! iMGOE.

Alternatively, a rare earth cobalt magnet bath may be used, and its performance is, for example, a coercive force of 8,200 to 88,000 E, a residual magnetic flux density of 8.4 to 9 Gauss, and a maximum energy product of approximately [7,5 to
It is 20MGOE.

The cylindrical discharge chamber 1 serves as a cathode or an anode during discharge, and is made of a hardly soluble metal such as graphite, tungsten, or molybdenum to withstand high temperatures.

Alternatively, as shown in Example 1, when the device of the present invention is used as a light source for emission spectroscopy, the cylindrical discharge chamber 1 is made of high-purity graphite for emission spectroscopy.

During discharge, the rod-shaped electrode 9 serves as an anode when the cylindrical discharge chamber 1 is an inertia electrode, and a cathode when the discharge chamber 1 is an anode. is made of soluble metal.

When the device of the present invention is used as a light source for emission spectroscopy, the rod-shaped electrode 9 is made of high-purity graphite for emission spectroscopy. .

If a solid fraction) 1 or a powdery solid is placed on the upper end plane 8 of the rod-like electrode 9 by a method such as forming a small hole, a plasma containing the components of the solid can be formed, which will be described later. As shown in Example 1, it can be used as a method for analyzing solid components.

The gas storage chamber 5 not only mixes plasma-forming gas and liquid spray, but also suppresses pressure fluctuations so that these mixtures are ejected from the tip of the cylindrical discharge chamber 1 at a constant pressure. It is made of a material that is highly insulating, heat resistant, and acid resistant, such as quartz.

Argon, helium, nitrogen, etc. are used as the plasma forming gas supplied to the gas storage chamber 5. Alternatively, a small amount of oxygen can be mixed into these gases, so that tungsten, rare earth elements, etc. inserted as solids are easily vaporized as oxides, and can be easily converted into plasma components.

In addition, the support part 6 and the water cooling part 7 are made of electromagnetically neutral metal,
For example, it is made of aluminum or brass.

When generating a plasma jet using the plasma jet generating device of the present invention, the gas introduction pipe 11
A gas for plasma formation is pressurized into the gas storage chamber 5, and is caused to flow into the cylindrical discharge chamber 1 through the gap between the inner peripheral wall of the gas storage chamber 1 and the outer peripheral surface of the rod 7 [pole 9]. It is ejected from the upper opening of 1.

- At the same time, a DC voltage of several tens to several hundreds of volts is applied between the cylindrical discharge chamber 1 and the rod-shaped electrode 9, and an arc discharge is caused with a current of several tens to several hundreds.

Then, due to the high temperature caused by the arc discharge, the plasma-forming gas is turned into plasma, and is discharged from the upper opening of the cylindrical discharge chamber 1.
Plasma jet and /', Jin, 01 comes out. 7 The discharge is started by causing a high frequency spark discharge between the cylindrical discharge chamber 1 and the rod-shaped electrode 9 to ignite an arc. Arc discharge occurs between the upper end surface 8 of the rod-shaped electrode 9 and the inner circumferential wall 4 of the cylindrical discharge chamber, and when an anode point is formed on the upper end surface 8, a cathode point is formed on the inner circumferential wall 4.
When a cathode spot is formed on the second end surface 8, an anode spot is formed on the inner circumferential wall 4. At this time, the cathode point and the anode point formed on the inner peripheral wall 4 are horizontally circularly formed on the inner wall surface of the inner peripheral wall 4 by the action of the current flowing in the circumferential direction around the magnetic lines of force generated by the annular magnet 2. make a rotational movement.

As a result, the shape of the arc discharge is stably formed into an umbrella shape, and a plasma jet is stably emitted from the upper opening of the cylindrical discharge chamber 1.

Furthermore, if cooling water is circulated through the water cooling section 7, the arc discharge and plasma jet will be cooled by the flow of cooling gas around them, and the so-called thermal pinch effect will keep the arc discharge and plasma jet on the axis of the cylindrical discharge chamber 1. However, if a large current of about 1008 or more is used, an even higher temperature can be generated due to the electromagnetic pinch effect.

Alternatively, a solution or liquid may be introduced in the form of a mist through the gas introduction 1'' 11, or a small piece or powder of a solid sample may be packed into a small hole drilled in the upper end surface 8 of the rod-shaped electrode 9 (1). When arc discharge is performed, the solid sample is evaporated and suffocated by the incandescent heat of the rod-shaped electrode 9, and the liquid sample is also evaporated and vaporized during the discharge and is introduced into the plasma, emitting spectral lines unique to liquid or solid samples. be able to. .

As described above, according to the method and apparatus of the present invention,
During arc discharge, the cathode point or the anode point undergoes horizontal circular rotational motion under the action of the magnetic field, so a stable arc is formed, and therefore a stable plasma jet flow can be maintained at a constant rate.

In addition, by mixing a liquid into a gas as a sample for arc discharge, or packing a solid onto an electrode, it is possible to obtain spectral lines specific to liquids or solids, and it can also be used as a light source for emission spectroscopic analysis. .

Historically, the device of the present invention does not require any additional device for stabilizing the plasma as in the prior art, and simply provides an annular magnet, so the device can be simplified and miniaturized.

Therefore, the lacerations do not become large and occupy a large space as in the conventional case, and the installation does not take up much space and is easy to operate.

Examples of the present invention will be described below.

Example 1 Phosphorus, sulfur, selenium, arsenic and antimony It can be used as a light source for quantitative luminescence analysis of almost any metal element including some anions in addition to iodine, rare earth elements, etc.

(a) Alkaline earth metal is MgO in plasma.

Cab, Bad, SrO Mg0H9Ca0H
j Ba0H.

It produces molecules such as 5rOH, and has the disadvantage that the atomic spectrum is weak because the proportion of molecules that exist as atoms is small.

However, in the present invention, by removing oxygen and moisture from the atmospheric gas, these drawbacks are overcome and a strong atomic spectrum is obtained.

In addition, alkaline earth metal elements include sulfuric acid groups and phosphoric acid groups and pyro compounds, such as CaP207. Make Ca25207 and evaporate 1. Although it is difficult to vaporize, according to the present invention, it is completely decomposed while passing through the high temperature region of the arc, and interferences such as sulfuric acid groups and phosphoric acid groups are removed.

Therefore, Mg I 2852.1291 (4-3e
V) r'Mg n:2802.6'95 A (43
9eV), Mg112795゜53X (4゜39ev)
.

CaI 4226.728X (2°92eV),
CaI [3933,666λ (3°14eV), 1
3a 15535°55 A (2,23eV),
BalI4554, 042 A (2,73eV)t
Using spectral lines such as Ba II 4934.0861 (2.50 eV), each element can be accurately quantitatively analyzed down to a concentration of 1 ppm or less.

(b) Rare earth elements tend to form oxides such as LaO in plasma and are easily ionized. For this reason, it has been difficult to analyze using conventional arc, spark discharge, or atomic absorption spectroscopy.

In other words, during arc and spark discharge, there are many ion beams in addition to atomic beams, so unless a large spectrometer with good dispersion is used, they cannot be detected and quantified separately from the spectral lines of other rare earth elements. Moreover, the energy is dispersed into many spectral lines, so the intensity of a single spectral line is weak, resulting in poor sensitivity.

Unfortunately, in atomic absorption spectrometry, even if we try to make a porcelain cathode 327°, which is essential for this analysis, we cannot obtain a good lamp that emits the strong resonance spectral line used for light absorption, so we cannot obtain a stable and sensitive lamp. Certain analyzes could not be performed.

However, according to the present invention, it is possible to adjust the cold air temperature to an appropriate temperature using only argon gas discharge, so it is easy to create conditions for strongly emitting only ion beams, compared to other fluorescent X-ray methods. Lay Ce, Prt with much better sensitivity
Nd, Smt Eu, Gd+TbyDy, Ha
, Er, Tm, Yb, I, u, Y, etc. can be analyzed.

(c) Tungsten is difficult to dissolve in acids and other liquids, and in the case of arc discharge, a graphite electrode and tungsten carbide (WC)
), making it difficult to evaporate or vaporize.

In the present invention, by using nitrogen or argon as a discharger and adding a small amount of oxygen at a flow rate of 0°451/mi, n, tungsten easily evaporates as WO2.
It vaporizes and decomposes in the high-temperature region of the discharge plasma, giving off the unique luminescence of tungsten.

Therefore, tungsten in steel, cast iron, etc. can be quantitatively analyzed with high precision using the W4(108,7(lA) spectrum line.

(d) Regarding general metal elements such as M+, Si, and A7 in steel and cast iron, Mn II 2933.6
6A z St I 2881.58X y AII
Quantitative analysis can be easily performed using the 3961°52X.

The sample is buried as a solid, for example in the form of a small chip, or in the form of a powder in a set of tt electrodes, and separated from the spectrum of the main component iron atoms using fractional evaporation to perform sensitive quantitative analysis. I can do it. .

First, dissolve the sample and reduce the concentration of the main component, for example iron, to 1.
000 ppm, and the analysis of Al was Ae I 3961
-X -Fel Use the 4005X line pair, eh, AI! -11) If Tlb is used, 09001% of crabs can be analyzed with high accuracy.

(e) In addition, strongly oxidizing elements such as titanium can be easily analyzed with good sensitivity according to the present invention.

(f) Arsenic, which could not be analyzed by conventional emission spectroscopy,
For selenium, antimony, phosphorus, sulfur, etc., the apparatus of the present invention can be easily connected to a vacuum spectrometer, so that spectral lines in the vacuum ultraviolet region, such as As I 1890-
4 A y Se I 1960゜9λtsb1206
8°3A, P I 1782. ．． 9 A, S
It can be analyzed more easily using 1826.25X.

Furthermore, regarding mercury and boron, Hg I 1849°6
By using the vacuum ultraviolet spectral line of Aj B I 1820°4A, quantitative analysis can be performed with higher sensitivity and precision.
I can do it.

Example 2 The plasma jet obtained according to the present invention can also be used as a heat source for high temperature chemical reactions.

According to the present invention, 17. High temperatures reaching OOO'C, 7
Alternatively, high-temperature plasma at any temperature can be easily and constantly formed. In a high-temperature plasma, substances that exist as solids at room temperature easily vaporize and become a component of the plasma, and undergo free thermal movement like gases.

Such reactions in plasma have a certain relationship with conventional chemical reactions at room temperature or relatively low high temperatures, but they also enable reactions that cannot occur in conventional chemical reactions.

Therefore, in high-temperature plasma, reactions that cannot occur at room temperature to low temperature can proceed at extremely high speeds, and various substances can be produced.

Below are some examples.

(a) Extracting hydrochloric acid from NaC,g aqueous solution 1, 2
NaCd + HzO412HCl+ Na202Na
C6+2SiO2・Al2O3 fist 21120 d 21
LCl+2S102・Al2O3・Na2O-1-2H
As 20S i02.Al2O3.2H20, kaolin or metakaolin can be used.

(b) 2FeC'f? 3+3H20->Fe2O
3+ 6I-ICl Through this reaction, fine particles of γ-iron oxide and hydrochloric acid can be produced, and separation of the two is extremely easy.

(c) Production of fine metal powder Ultrafine metal particles can be produced by vaporizing solid metal in an oxygen-free atmosphere, cooling and recovering it.

[Brief explanation of drawings]

FIG. 1 is a sectional view of a conventional plasma jet generating device, FIG. 2 is a sectional view showing an embodiment of the plasma jet generating device of the present invention, and FIG. 3 is a plan view thereof. DESCRIPTION OF SYMBOLS 1... Cylindrical discharge chamber, 2... Annular magnet 1, 9... Rod-shaped electrode. Shin Ogawa, Patent Attorney for Nakano Electronics Co., Ltd., a sub-agent of the Director of the Agency of Industrial Science and Technology - Patent Attorney Ken Noguchi Teru Patent Attorney Kazuhiko Saishita Figure 1 3'

Claims (1)

[Claims] 1. In a method of unifying a plasma jet by arc discharge, a cathode point or an anode point is circularly rotated in a horizontal plane by the action of a magnetic field, and this cathode point or anode point is connected to another anode point. A plasma jet generation method characterized by causing arc discharge to occur between a point or a cathode point. 2 Consisting of an annular magnet and a cylindrical discharge chamber with both ends open, which is centrally provided at the center of the annular magnet, and a cylindrical discharge chamber with a spaced apart from the inner circumferential wall of the cylindrical discharge chamber. A plasma jet generating device characterized in that rod-shaped electrodes are provided concentrically, and plasma-forming gas is supplied through a gap between the cylindrical discharge chamber and the rod-shaped electrodes.