JPH04292783A - Soaking plasma image heater - Google Patents

Abstract

PURPOSE:To improve uniformity and stability of a temperature by providing a cavity resonator incorporating an egg type plasma lamp at a first focus of an elliptical mirror and formed of a radio wave shielding plate at the side end of the first focus, and a high frequency oscillator. CONSTITUTION:A microwave power of high frequency is applied from a high frequency oscillator 7 to a cup-like cavity resonator 5 formed at its end of an elliptical mirror l of a radio wave shielding plate 4 through a waveguide 6 and a rotary fitting 15. An egg type plasma lamp 2 contained in the resonator 5 generates a plasma light to generate an intense light. The light is reflected on the inner surface of the mirror 1 and condensed to a sample 8 of a second focus. Thus, the sample is highly heated to be melted. When the sample 8 is lifted while being slowly rotated, a crystal is grown. Since the lamp 2 can correct distribution of light at the second focus to uniformly condense it due to the egg shape of a light source, the entire periphery of the sample can be uniformly heated, and its high speed rotation is not required.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an improvement in a soaking plasma image heating apparatus for an image furnace used, for example, for crystal growth of semiconductor materials.

0002

[Prior Art] FIG. 24 shows, for example, Japanese Patent Application Laid-Open No. 63-22348.
FIG. 7 is a sectional view of a conventional soaking plasma image heating device disclosed in Publication No. 7. In the figure, 1 is an ellipsoidal mirror that has an ellipsoidal reflective surface inside, 11 is a light source such as a halogen or xenon lamp that is installed at the first focal point of the ellipsoidal mirror 1 and emits light 9, and 12 is this light source. A power supply is connected via a wire 13 to supply power to 11, and 8 is a sample placed at the second focus of the ellipsoidal mirror 1.

Next, the operation will be explained. The light from the light source 11 is focused on the sample by the ellipsoidal mirror 1 and heated, and the rod-shaped sample 8 is dissolved. In this melted portion, as the sample 8 moves in the axial direction, the raw material dissolves into the solution in the melting portion, and crystals grow. Since the composition of this solution and the composition of the raw material are always in equilibrium, the composition of the crystal is maintained homogeneous. Therefore, it is attracting attention as the most suitable method for producing single crystals with a uniform dopant concentration.

0004

Since the conventional soaking plasma image heating apparatus is constructed as described above, it is still widely used as a single crystal manufacturing apparatus. However, if a lamp with electrodes, such as a halogen lamp or a xenon lamp, is used as a light source, the wavelength of the light cannot be selected, so the light is absorbed only at the surface of the sample. In this state, the interface between the floating molten part and the raw material has an upwardly convex shape, and the solution flows downward. Therefore, the diameter of the single crystal could not be increased, and only crystals with a small diameter of about 1 cm could be produced.

On the other hand, as a method for increasing the diameter of a sample, a crystal pulling method using a crucible has been used, but it has been impossible to produce pure crystals due to contamination of the crucible. This is a problem especially when manufacturing large-diameter optical crystals, etc. Conventionally, crucibles have been used, but there are still problems such as impurities mixed in from the crucible and uneven crystal quality. Perfect optical crystals are not mass-produced.

[0006] Perfecting crystals is a very important issue in applications such as laser rods, but there has been no method for manufacturing large diameter crystals in place of the crucible method. Image heating devices using the floating molten zone method are expected, but since the crystal material is heated from the surface, it is not possible to retain the solution and large diameter crystals have not been manufactured. Therefore, new manufacturing equipment was desired.

[0007] Furthermore, in the case of halogen lamps, the lifespan of the lamp is very short, about 40 hours (for space use; about 200 hours for ground use), so many spare halogen lamps are required, and this is difficult in the mass production of optical crystals. This was a fatal problem.

Furthermore, in the case of halogen or xenon lamps, it is not possible to melt glass directly with light; in the case of terrestrial lamps, it is possible to melt glass indirectly by putting it in a crucible or by heating a ceramic material with light. It was heated, etc. Also,
In microgravity experiments in space, glass was placed in a platinum wire mesh cage, and the wire mesh cage was heated using image heating to indirectly heat the glass. For this reason, when a light-transmitting material such as glass is melted, impurities from the crucible and platinum from the cage enter the material, causing quality deterioration. This has been a major obstacle in the processing of materials such as far-infrared fibers. That is, one of the causes of increasing the loss of far-infrared fibers is impurities such as heavy ions mixed in the crucible and materials. This cannot be removed unless a crucible is used.

Furthermore, since the conventional light source heats a narrow area, it is not possible to uniformly heat the sample in the circumferential direction. Therefore, a method of rotating the sample at a high speed of 100 rpm to make the temperature uniform is used. ing. However, applying such high-speed rotation to the sample inhibits the uniform growth of the crystal, and in microgravity experiments, artificial gravity is created, which causes air bubbles to get inside the crystal due to centrifugal force and never come out. A serious problem arises: At present, this problem has not yet been solved worldwide, and there are concerns that the image reactor used in Shaft's space experiments uses a method that rotates the sample at high speed and heats it uniformly, so the effect of microgravity may not be fully demonstrated. be done.

[0010] This invention was made to solve the above-mentioned problems, and the light source is an egg-shaped plasma lamp that has an excellent heat uniformity effect.By rotating this, the incident distribution of light on the sample can be changed. In addition, the temperature gradient on the surface of the sample is appropriately set by adjusting the temperature uniformly and making the light incident on the entire circumference of the sample. In addition, it has a long life, can melt glass at a wavelength in the absorption band by selecting the heating wavelength, and makes it possible to increase the diameter of optical crystals.

[0011]

[Means for Solving the Problems] The soaking plasma image heating device according to the present invention has an element sealed in a transparent container such as quartz or transparent ceramics as a light source, and the element is heated by microwave (2. An egg-shaped plasma lamp is used, which generates plasma in an egg-shaped container by heating it in the microwave frequency band around 4 GHz, and utilizes the emitted light. This egg-shaped plasma lamp is housed in a bowl-shaped cavity resonator formed by an ellipsoidal mirror and a radio wave shielding plate, and is equipped with an ellipsoidal mirror that focuses the emitted light from the egg-shaped plasma lamp onto the sample. An ellipsoidal mirror is placed at one focal point in the short axis direction, and a part of the sample is uniformly heated and melted while the sample is moved in the short axis direction to grow crystals.

A soaking plasma image heating device according to another invention houses the above-mentioned egg-shaped plasma lamp in a cup-shaped cylindrical cavity resonator, and has an elliptical shape that focuses the light emitted from the egg-shaped plasma lamp onto a sample. A sample is placed in the short axis direction at one focal point of the ellipsoid mirror, and a part of the sample is heated and melted while the sample is moved in the short axis direction to grow crystals. This is what I did.

[0013] In addition, a soaking plasma image heating device according to another aspect of the present invention has an element sealed in an egg-shaped transparent container made of quartz or transparent ceramics as a light source, and the element is heated using microwaves. An egg-shaped plasma lamp is used, which is heated at a microwave oven frequency around 2.4 GHz to create plasma in a container and utilizes the emitted light. This egg-shaped plasma lamp is housed in a bowl-shaped cavity resonator formed by an ellipsoidal mirror and a radio wave shielding plate, and is equipped with an ellipsoidal mirror that focuses the emitted light from the egg-shaped plasma lamp onto the sample. The ellipsoidal mirror is placed on the long axis including the focal point, and the sample is moved in the long axis direction while heating and melting part of the sample to grow crystals.

Further, a soaking plasma image heating device according to another aspect of the present invention houses the above egg-shaped plasma lamp in a cup-shaped cylindrical cavity resonator, and emits light emitted from the egg-shaped plasma lamp onto a sample. Equipped with an ellipsoidal mirror for condensing light, a sample is placed in the long axis direction at one focal point of the ellipsoidal mirror, and a part of the sample is heated and melted while the sample is moved in the long axis direction to crystallize it. It is designed to grow.

Furthermore, a soaking plasma image heating device according to another aspect of the present invention houses the above egg-shaped plasma lamp in a bowl-shaped cavity resonator formed by an ellipsoidal mirror and a radio wave shielding plate. , an ellipsoidal mirror that focuses the light emitted from the egg-shaped plasma lamp onto the sample, a reactor tube that houses the sample, a radiation thermometer that faces a part of the sample, a motor that rotates the sample, and a motor that moves the sample. A moving device is installed to move the sample in the minor axis direction while heating and melting the sample to grow crystals.The temperature of the sample is measured with a radiation thermometer and the information is used for temperature control. In addition, the sample is placed in the furnace tube and the atmosphere around the sample is controlled.

Furthermore, another invention of the present invention is that in the above case, the sample is placed on the long axis including the focal position of the ellipsoidal mirror, and a part of the sample is heated and melted while the sample is lengthened. It grows crystals by moving in the axial direction.

Furthermore, a soaking plasma image heating device according to another aspect of the present invention is provided with a rotating device for rotating the above-mentioned egg-shaped plasma lamp, and is housed in a bowl-shaped or cup-shaped cylindrical cavity resonator. , is equipped with an ellipsoidal mirror that focuses the light emitted from the egg-shaped plasma lamp onto the sample.The sample is placed in the short axis direction at one focal point of the ellipsoidal mirror, and a part of the sample is heated and melted. The sample is moved in the minor axis direction to grow crystals. It is also possible to measure the temperature of the sample with a radiation thermometer and use that information for temperature control. It is also possible to control the atmosphere around the sample by placing the sample in the furnace tube.

A soaking plasma image heating device according to still another invention is provided with a rotating device for rotating the egg-shaped plasma lamp, which is housed in a bowl-shaped or cup-shaped cylindrical cavity resonator. Equipped with an ellipsoidal mirror that focuses the light emitted from the plasma lamp onto the sample, the sample is placed in the long axis direction at one focal point of the ellipsoidal mirror, and a part of the sample is heated and melted while the sample is lengthened. It grows crystals by moving in the axial direction. It is also possible to measure the temperature of the sample with a radiation thermometer and use that information for temperature control. It is also possible to control the atmosphere around the sample by placing the sample in the furnace tube.

[0019]

[Operation] Since the light source of the egg-shaped plasma lamp according to the present invention is egg-shaped, the distribution of light at the second focal point can be corrected and the light can be focused more evenly than a spherical plasma lamp, so that it can cover the entire circumference of the sample. Uniform heating is possible, and high-speed rotation is not required. In addition, since the emission wavelength of the lamp can be set from ultraviolet to infrared, image heating can be performed in the absorption band of the material when producing crystals of optical materials such as laser rods using the floating melt zone method, making it possible to increase the diameter of the crystal. It becomes possible.

In another aspect of the present invention, the cavity resonator of the plasma lamp is shaped like a cup to facilitate combination with a spheroidal mirror.

In yet another invention, in the above case, by moving the sample on the short axis of the ellipsoidal mirror, it is possible to produce short crystals with very long lengths.

[0022] In yet another invention, in the above case, by moving the sample on the long axis of the ellipsoidal mirror, the light distribution around the sample is made extremely uniform and the light collection efficiency is kept at its highest. be.

In still another aspect of the invention, in the above case, the atmosphere inside the furnace tube is controlled and a sample moving mechanism is provided, so that high-quality crystals can be produced by the floating molten zone transfer method.

In still another aspect of the invention, in the above case, the atmosphere inside the furnace tube is controlled, a sample moving mechanism is provided, and the egg-shaped plasma lamp is rotated, so that more uniform heating is possible.

[0025]

Embodiments Embodiment 1 Hereinafter, a soaking plasma image heating apparatus according to an embodiment of the present invention will be explained with reference to the drawings. FIG. 1 is a sectional view showing the configuration of a soaked plasma image heating device according to an embodiment of the present invention, in which 1 is an ellipsoidal mirror, 2 is a hollow egg-shaped container (slip caster) made of glass or translucent ceramic. 3 is an egg-shaped plasma lamp that encapsulates elements such as potassium inside a lamp (can be produced by a method) and generates plasma light by microwave heating, emitting light 9. 3 is a support made by processing a highly thermally conductive ceramic into a rod shape. 4 is a radio wave shielding plate attached with its disc-shaped peripheral edge touching the inside of the ellipsoidal mirror 1; 5 is a bowl-shaped cavity resonator formed by the end of the ellipsoidal mirror 1 and the radio wave shielding plate 4; , 6 is a waveguide attached to a hole made at the end of the ellipsoidal mirror 1, 7 is a high frequency oscillator attached to the other end of the waveguide 6, and 8 is a short wave transmitter at the second focal point of the ellipsoidal mirror 1. A rod-shaped sample 15 installed in the axial direction is a rotating tool that rotates at the end of the ellipsoidal mirror 1 to which a support 3 is fixed, and is made of a radio wave transparent material. The rotating tool 15 is used to smooth the focused light distribution on the sample 8 by rotating the egg-shaped plasma lamp 2.

FIG. 2 is a diagram illustrating the configuration of the vicinity of the egg-shaped plasma lamp 2. As shown in FIG. In the figure, microwave power of 1 kW to 5 kW at a high frequency such as 2 GHz is applied from a high frequency oscillator 7 to a cavity resonator 5 via a waveguide 6 and a rotary tool 15. The egg-shaped plasma lamp 2 housed in the cavity resonator 5 generates plasma and emits powerful light of about 3 kW. This light is reflected by the inner surface of the ellipsoidal mirror 1 and focused onto the sample 8 at the second focal point. Here, sample 8 becomes highly heated and melts. When sample 8 is slowly rotated and pulled up, crystals grow.

FIG. 3 is a cross-sectional view of the egg-shaped plasma lamp 2, and FIG. 4 is a perspective view showing the structure of the egg-shaped plasma lamp. In these figures, the egg-shaped plasma lamp 2 is made of translucent ceramics and manufactured by a slip casting method, and can be formed into any shape. Here, the light distribution is set to an oval shape that is particularly suitable for the floating melt zone migration method.

FIG. 5 shows sample 8 produced by egg-shaped plasma lamp 2.
In order to represent the light distribution in the circumferential direction on the side surface of the sample, the sample is sliced into rings and the light distribution in the cross section is shown. In this case, the temperature distribution on the side surface of the sample 8 is as shown in Figure 5, where the light circulates around the entire circumference, making uniform heating possible and improving the light collection efficiency.Therefore, there is no need to rotate at high speed as in the conventional case. It rotates at a low speed to create a solid-solution layer interface 17 between solid and liquid, and crystal growth can be performed at a low rotation speed that can create a clean laminar flow at the solid-solution layer interface 17. The egg-shaped plasma lamp's image approaches a nearly perfect sphere at the second focal point, resulting in improved uniformity and improved light collection efficiency.

FIG. 6 shows sample 8 (
Here, we show the results of a heating experiment for aluminum (aluminum) using a single elliptic soaking plasma image heating device, where the horizontal axis shows time and the vertical axis shows temperature. The plasma lamp 2 used in the experiment emits light at a near-infrared wavelength of 0.76 microns. As can be seen from this figure, the aluminum sample 8 reached 660 degrees and melted in about 2 minutes. The plasma lamp 2 input power at this time is approximately 300W.
It is.

FIG. 7 shows the calculation of the difference in light concentration distribution between a spherical plasma lamp and an egg-shaped plasma lamp in a cross section that includes the radius of sample 8. It can be seen that the egg-shaped plasma lamp has a more uniform distribution than the spherical one. I can say something.

Furthermore, FIG. 8 shows the maximum temperature reached in the case of tungsten sample 8 determined by analysis. In this case, calculations are made for three types of lamp shapes: 10, 20, and 30 mm. In this way, it exhibits superior heating performance compared to furnaces using xenon lamps currently on the market. By selecting the diameter of the lamp, you can choose to focus light sharply or over a wide range. This is because the emission spectrum of the plasma lamp 2 can be concentrated in the wavelength where the absorbance of the sample 8 is highest, for example in the near-infrared region, so it is possible to obtain extremely high heating efficiency compared to xenon lamps, etc. be.

FIG. 9 is a diagram showing the result of actually measuring the emission spectrum of the plasma lamp 2. In this case, the plasma lamp 2 is filled with potassium so that it emits light of 0.76 microns, so there is a sharp emission spectrum in this area. Luminescence can be seen. When such wavelength selectivity is used, light enters the inside of the sample 8, which generates heat from inside, and the solid solution layer interface 17 between the molten part and the solid part of the sample 8 becomes flat or concave, causing melt leakage. Can prevent leakage. Therefore, it is possible to process a sample 8 having a larger diameter than in the conventional method using the floating zone method.

Furthermore, FIG. 10 is a diagram showing the shape of the solid solution layer boundary surface 17 between the molten part 16 and the solid of the sample 8, and in this case shows the case of irradiation with a halogen lamp or a xenon lamp. The light is incident only on the surface of the sample 8, heats the surface, and gradually diffuses and spreads inside. It is melted to a thickness approximately close to the radius of sample 8, and the solid solution layer interface 1 is formed as shown in the figure.
7 has a mountain shape, and the melted portion 16 has a shape that tends to drip downward.

FIG. 11 also shows the melted part 16 of sample 8.
This figure shows the shape of the solid solution layer boundary surface 17 between the solid and the solid solution layer, and in this case, the case of irradiation with the plasma lamp 2 is shown. Since the light penetrates into the inside of the sample 8, it is diffused and spread inside. Since the temperature gradient inside the sample 8 is almost eliminated, the solid solution layer boundary surface 17 is horizontal or bowl-shaped as shown in the figure, and the molten part 16 has a shape that prevents it from dripping downward. Therefore, even if the diameter of the sample 8 increases, the molten part 16 will not drip down, making it possible to grow large crystals using the floating zone method.

Embodiment 2 Next, another embodiment of the invention is shown in FIG. Further, the structure around the egg-shaped plasma lamp 2 is shown in FIG. In the figure, reference numeral 10 indicates a cavity resonator 5 which is formed by bringing the open side peripheral edge of a cup-shaped radio wave shield 10 into contact with the first focus side of the ellipsoidal mirror 1, and placing an egg-shaped plasma lamp 2 inside the cavity resonator 5. Make it emit light. In this case, the optimum light emission conditions of the egg-shaped plasma lamp 2 can be maintained regardless of the shape of the ellipsoidal mirror 1.

Embodiment 3 Still another embodiment of the invention is shown in FIG. In the figure, 1 is an ellipsoidal mirror, 2 is a hollow ellipsoidal egg-shaped container made of glass or translucent ceramic, and elements such as potassium are sealed inside, and plasma is emitted by microwave heating to produce light 9.
3 is a support made by processing highly thermally conductive ceramic into a rod shape; 4 is a radio wave shielding plate attached with the disk-shaped periphery touching the inside of the ellipsoidal mirror 1; 5 is a microwave cavity formed by the end of the ellipsoidal mirror 1 and the radio wave shielding plate 4; 6 is a waveguide attached to a hole drilled in the end of the ellipsoidal mirror 1; and 7 is a waveguide. A high frequency transmitter is attached to the other end of the wave tube 6, 8 is a rod-shaped sample placed on the long axis at the second focal point of the ellipsoidal mirror 1, and 15 is the end of the ellipsoidal mirror 1 with the support 3 fixed thereto. It is a rotary tool that rotates at the same time, and is made of a material that is transparent to radio waves. This rotating tool 15
In this method, the distribution of focused light on the sample 8 is changed by rotating the egg-shaped plasma lamp 2 to obtain a uniform distribution.

Embodiment 4 Next, another embodiment of the invention is shown in FIG. Further, the distribution of light condensed on the sample 8 is shown in FIG. In the figure, reference numeral 10 indicates a cavity 5 which is formed by bringing the open side peripheral edge of a cup-shaped radio wave shield into contact with the first focal point side of the ellipsoidal mirror 1, and an egg-shaped plasma lamp 2 placed inside the cavity 5, which emits light. let In this case, the optimum light emission conditions of the lamp can be maintained regardless of the shape of the ellipsoidal mirror 1. As shown in FIG. 16, all of the light is focused on the melted part 16 of the sample 8, and the surrounding area is uniformly irradiated. Therefore, since the light collection efficiency is greatly improved, uniform and efficient heating can be achieved.

Embodiment 5 Still another embodiment of the invention is shown in FIG. In the figure, 1 is an ellipsoidal mirror, 2 is a hollow ellipsoidal egg-shaped container made of glass or translucent ceramic, and elements such as potassium are sealed inside, and plasma is emitted by microwave heating to produce light 9.
3 is a support made by processing highly thermally conductive ceramic into a rod shape; 4 is a radio wave shielding plate attached with the disk-shaped periphery touching the inside of the ellipsoidal mirror 1; 5 is a microwave cavity resonator formed by the end of the ellipsoidal mirror 1 and the radio wave shielding plate 4, 6 is a waveguide attached to a hole made in the end of the ellipsoidal mirror 1, and 8 is an ellipsoid. A rod-shaped sample placed on the short axis at the second focal point of the body mirror 1; 18 is a reactor core tube made of a cylindrical quartz tube that houses the sample 8;
9 is a motor for rotating the sample 8 attached above and below the furnace tube 18, and 20 is a moving device that moves the sample 8 in the axial direction at a low speed, and has the same configuration as the conventional device. The moving device is composed of a radiation thermometer 21 that measures the temperature of the sample 8 through a temperature observation window 22 made of quartz as a part of the ellipsoidal mirror 1; Observe the sample 8 through the window 22. 23 is a control computer connected to the radiation thermometer 21 and the heating power source; 25 is a magnetron that is supplied with power from the heating power source 24 and emits high frequency waves; 26 is a gas cylinder that stores gas; 27 is a valve; and 28 is a flow rate regulator. , 29 are vacuum pumps. The atmosphere control device 32 is composed of elements 26 to 29.

With this structure, while heating the sample 8, the atmosphere is controlled by the flow rate regulator 28 or the vacuum pump 29.
While rotating the sample 8 around its axis using the motor 19, the sample 8 is slowly moved in the axial direction by the moving device 20 at a low speed of about 10 mm per hour to grow crystals. The rotation speed of sample 8 at this time was conventionally 100 rpm.
In the present invention, uniform heating can be performed around the side surfaces of the sample 8, so such high speed rotation is no longer necessary. In the case of this invention, the purpose of rotation is simply to create a clean interface of the solid solution layer, so low speed rotation of about 10 rpm is sufficient. Further, the temperature of the sample 8 is measured with a radiation thermometer 21 via a temperature observation window 22 at a wavelength around 0.9 microns to grasp the temperature, and the heating power source is controlled by a control computer 23 to control the transmission of the magnetron 25. Control the temperature of sample 8 to a desired value. At this time, the change in emissivity on the surface of the sample 8, which is a cause of error in temperature measurement, can be corrected by using a simple emissivity monitor.

Embodiment 6 Next, another embodiment of the invention is shown in FIG. In the figure, 10 is a cup-shaped radio wave shield 1 on the first focus side of the ellipsoidal mirror 1.
0 contact the open side peripheral parts to form a cavity resonator 5,
An egg-shaped plasma lamp 2 is placed inside this and emitted light. In this case, the optimum light emission conditions of the lamp can be maintained regardless of the shape of the ellipsoidal mirror 1.

Embodiment 7 Still another embodiment of the invention is shown in FIG. In the figure, 1 is an ellipsoidal mirror, 2 is a hollow ellipsoidal egg-shaped container made of glass or translucent ceramic, and elements such as potassium are sealed inside, and plasma is emitted by microwave heating to produce light 9.
The egg-shaped plasma lamps 2 and 3 that emit energy are supports made by processing highly thermally conductive ceramic into rod shapes, and 4 is a radio wave shielding plate attached with its disk-shaped periphery in contact with the inside of the ellipsoidal mirror 1. , 5 is a microwave cavity formed by the end of the ellipsoidal mirror 1 and the radio wave shielding plate 4, 6 is a waveguide attached to a hole made in the end of the ellipsoidal mirror 1, and 8 is a microwave cavity resonator formed by the end of the ellipsoidal mirror 1 and the radio wave shielding plate 4. Ellipsoid mirror 1
A rod-shaped sample is placed on the long axis by making a hole at the end of the ellipsoidal mirror 1 at the second focus of the rod, and 14 is a window made at the contact point of the waveguide 6 and the ellipsoidal mirror 1. be. 18 is a furnace tube made of a cylindrical quartz tube that houses the sample 8; 19 is a motor for rotating the sample 8 attached to the end of the furnace core tube 18; and 20
2 is a moving device for moving the sample 8; 21 is a radiation thermometer that measures the temperature of the sample 8 through a temperature observation window 22; the sample 8 is observed through a hole made in the ellipsoidal mirror 1; 23 is a radiation thermometer 21 and a control computer connected to a heating power source; 25
26 is a magnetron that is supplied with power from the heating power source 24 and emits high frequency waves; 26 is a gas cylinder that stores gas; 27
is a valve, and 28 is a flow regulator. The atmosphere control device 32 is composed of elements 26 to 29.

With this structure, while heating the sample 8, adjusting the atmosphere using the flow rate regulator 28, etc., and rotating the sample 8 around its axis using the motor 19, the sample 8 is heated by the moving device 20 in one hour. The sample 8 is slowly moved in the axial direction at a low speed of about 10 mm to grow crystals. Conventionally, sample 8 was rotated at a high speed of 100 rpm at this time (reverse rotation was applied to the top and bottom of the sample), but in this invention, the side surfaces of sample 8 were heated more uniformly and at a higher temperature than above. This eliminates the need for such high-speed rotation. In the case of this invention, the purpose of rotation is simply to create a clean interface of the solid solution layer, so low speed rotation of about 10 rpm is sufficient. Also, the temperature of the sample 8 was set to 0.0 with the radiation thermometer 21.
The temperature is determined by measuring at a wavelength around 9 microns, and the heating power source is controlled by the control computer 23 to control the transmission of the magnetron 25 to control the temperature of the sample 8 to a desired value. At this time, the change in emissivity on the surface of the sample 8, which is a cause of error in temperature measurement, can be corrected by using a simple emissivity monitor.

Embodiment 8 Next, another embodiment of the present invention is shown in FIG. In the figure, reference numeral 10 indicates a cavity 5 which is formed by bringing the open side peripheral edge of a cup-shaped radio wave shield into contact with the first focal point side of the ellipsoidal mirror 1, and an egg-shaped plasma lamp 2 placed inside the cavity 5, which emits light. let In this case, the optimum light emission conditions of the lamp can be maintained regardless of the shape of the ellipsoidal mirror 1. All of the light is focused on the molten part 16 of the sample 8 and uniformly irradiated around it. Therefore, since the light collection efficiency is greatly improved, efficient heating can be achieved. Figure 21 is an external view of the configuration shown in Figure 20 when it is configured into an actual soaking plasma image heating device. 32 is an atmosphere control device, which has an airtight structure with a door for sample manipulation. Since it is configured in this way, it can be used for microgravity experiments in space such as the space shuttle.

Embodiment 9 Next, another embodiment of the present invention is shown in FIG. In the figure, 1 to 5 are the same as the above invention, 3
3 is a pulley attached to a rotary tool 15 and connected to a motor 35 via a belt 34.

With this configuration, the rotation of the motor 35 can provide rotation of several tens of rpm to the egg-shaped plasma lamp. This rotation makes the light focused on the surface of the sample 8 very uniform, and compared to the conventional method of rotating the sample at high speed to make the temperature uniform, the light condensed on the surface of the sample 8 becomes much more uniform.
It is possible to lower the rotation of the In other words, as far as temperature uniformity is concerned, there is no need to rotate the sample 8, so it is only necessary to rotate it for the purpose of stirring the solution. If stirring of the solution is not required, rotation is no longer necessary. Therefore, since crystal growth can be performed under complete diffusion control in microgravity experiments, an ideal crystal growth apparatus can be provided. Furthermore, since the bowl-shaped cavity resonator 5 is used, the egg-shaped plasma lamp 2 can be replaced by simply removing the radio wave shielding plate 4, which simplifies the maintenance and specification procedures of the device.

Embodiment 10 Next, another embodiment of the present invention is shown in FIG. In the figure, 1 to 5 are the same as the above invention, 3
3 is a pulley attached to a rotary tool 15 and connected to a motor 35 via a belt 34.

With this structure, the rotation of the motor 35 can provide rotation of several tens of rpm to the egg-shaped plasma lamp. This rotation makes the light focused on the surface of the sample 8 very uniform, and compared to the conventional method of rotating the sample at high speed to make the temperature uniform, the light condensed on the surface of the sample 8 becomes much more uniform.
It is possible to lower the rotation of the In other words, as far as temperature uniformity is concerned, there is no need to rotate the sample 8, so it is only necessary to rotate it for the purpose of stirring the solution. If stirring of the solution is not required, rotation is no longer necessary. Therefore, since crystal growth can be performed under complete diffusion control in microgravity experiments, an ideal crystal growth apparatus can be provided. Furthermore, since the cup-shaped radio wave shield 10 is used, good light emission conditions can be maintained regardless of the shape of the ellipsoidal mirror 1.

[0048]

Since the present invention is constructed as described above, the emission spectrum can be selected from the ultraviolet region to the infrared region, so that a wide range of samples can be heated. In particular, since it can be melted by image heating at wavelengths in the absorption band of optical materials, it is extremely effective for the space and terrestrial production of pure far-infrared glass, which dramatically improves the efficiency of fiber cables, for example. Furthermore, in the production of laser crystals such as YIG, crystals with a large diameter of 2 cm or more can be produced by the floating melt zone transfer method, and the performance of conventional crystals can be dramatically improved. In other words, the impurities in the crystal are completely controlled and a crystal with a large diameter without defects can be produced, making it possible to increase the output of the laser. As described above, this is an innovative device for producing materials, and can contribute to the production of new materials on the ground or in space.

Furthermore, as described above, since the light emitting shape of the egg-shaped plasma lamp is egg-shaped, the light can be evenly focused around the sample, and further uniformity can be achieved by rotating the egg-shaped plasma lamp. As a result, even if the rotation speed of the sample is slowed down, variations in the temperature of the suspended solution can be suppressed, and high-quality crystals can be grown, making it possible to obtain high-quality crystals without cracks. In other words, since the sample can be heated uniformly, there is no need for much rotation, and crystal growth can be performed at low speed rotation, which has a good effect because it suppresses the movement of the solution that inhibits crystal growth. Particularly in crystal growth experiments in microgravity, there is no unnecessary movement of the solution, and a uniform distribution of components due to diffusion is obtained, making it possible to ideally grow crystals. Moreover, it becomes possible to remove bubbles inside the solution. In other words, bubbles can be moved outward by Marangoni convection due to thermal gradients.

Furthermore, since electrodeless discharge is utilized, the life of the lamp is extremely long and can exceed 10,000 hours, making it possible to provide a furnace with a life 100 times longer than conventional lamps.

Furthermore, since the lamp is small and lightweight and the ellipsoidal mirror can be made small, the entire device can be constructed compactly, which is an extremely important advantage in space.

In another invention related to this invention, since the cavity resonator is cup-shaped, the same egg-shaped plasma lamp can be used in various shapes without being affected by the shape and size of the ellipsoidal mirror. It can be made compatible with ellipsoidal mirrors. Also,
The egg-shaped plasma lamp can be easily replaced to change the shape and emission spectrum according to the sample, making it a very effective means for processing materials.

Furthermore, in another invention, in addition to the above-mentioned effects, since the sample 8 is moved on the long axis of the ellipsoidal mirror, the light collection efficiency is good and the light distribution is extremely uniform.
Helps prevent crystal defects.

Furthermore, in another invention related to this invention, in addition to the above-mentioned effects, since the cavity resonator is cup-shaped, it is not affected by the shape and size of the ellipsoidal mirror, and the same egg-shaped plasma can be produced. The lamp can be adapted to ellipsoidal mirrors of various shapes. In addition, the plasma lamp can be easily replaced to change its shape and emission spectrum to match the sample 8, making it a very effective means for processing materials.

Furthermore, in another invention, in addition to the above effects, the temperature of the sample can be measured via the reactor core tube, and sample 8
temperature can be determined. Suppressing temperature fluctuations has the effect of preventing crystal defects and is therefore effective in producing high quality products.

Furthermore, in another invention related to this invention, in addition to the above-mentioned effects, since the cavity resonator is cup-shaped, it is not affected by the shape and size of the ellipsoidal mirror, and the same egg-shaped plasma can be produced. The lamp can be adapted to ellipsoidal mirrors of various shapes.

Furthermore, in another invention, in addition to the above-mentioned effects, the temperature of the sample can be made more uniform by rotating the egg-shaped plasma lamp, which has the effect of suppressing temperature fluctuations and preventing crystal defects, thereby improving quality. It is possible to produce good crystals.

In addition to the above-mentioned effects, in another invention related to the present invention, even better uniformity can be obtained since the egg-shaped plasma lamp is rotated with the sample on the long axis. Furthermore, the temperature distribution of the sample can be changed by adjusting the shape of the egg-shaped plasma lamp, allowing the optimum distribution for crystal growth to be selected.

In the above explanation, the shape of the plasma lamp was limited to an oval shape, but this shape can be set to any shape such as a sphere, cylinder, oval, ellipsoid, cube, triangular pyramid, etc. It is effective.

[0060]

[Brief explanation of drawings]

FIG. 1 is a sectional view showing an embodiment of the present invention.

FIG. 2 is a partial cross-sectional view illustrating the configuration near the egg-shaped plasma lamp.

FIG. 3 is a sectional view illustrating the configuration of an egg-shaped plasma lamp.

FIG. 4 is a perspective view illustrating the configuration of an egg-shaped plasma lamp.

FIG. 5 is an analysis result of the light intensity distribution on the surface of the sample.

FIG. 6 is data from a heating experiment.

FIG. 7 is an analysis result comparing the light intensity distribution on the surface of a sample between spherical and egg-shaped plasma lamps.

FIG. 8 is an analysis result of the maximum temperature reached.

FIG. 9 is a diagram showing the emission spectrum of a plasma lamp.

FIG. 10 is a diagram showing the shape of a solid solution layer boundary surface in a conventional floating melt zone movement method.

FIG. 11 is a diagram showing the shape of a solid solution layer boundary in the floating melt zone movement method of the present invention.

FIG. 12 is a configuration block diagram showing an embodiment of another invention.

FIG. 13 is a diagram illustrating the configuration of an egg-shaped plasma lamp according to another invention.

FIG. 14 is a block diagram showing the configuration of yet another embodiment of the invention.

FIG. 15 is a block diagram showing the configuration of yet another embodiment of the invention.

FIG. 16 is a diagram showing the distribution of light when the sample is placed on the long axis.

FIG. 17 is a block diagram showing the configuration of yet another embodiment of the invention.

FIG. 18 is a block diagram showing the configuration of yet another embodiment of the invention.

FIG. 19 is a block diagram showing the configuration of yet another embodiment of the invention.

FIG. 20 is a block diagram showing the configuration of yet another embodiment of the invention.

FIG. 21 is an external view of the configuration of an image heating device using an egg-shaped plasma lamp.

FIG. 22 is a block diagram showing the configuration of yet another embodiment of the invention.

FIG. 23 is a block diagram showing the configuration of yet another embodiment of the invention.

FIG. 24 is a block diagram showing the configuration of a conventional image heating device.

[Explanation of symbols]

1 Ellipsoidal mirror 2　Egg-shaped plasma lamp 3 Support equipment 4 Radio wave shielding plate 5 Cavity resonator 6 Waveguide 7 High frequency oscillator 8 Sample 9. Light 10 Cup-shaped radio wave shielder 11 xenon lamp 12 Power supply 13 Wire 15 Rotating tool 16 Melting part 17 Solid solution layer interface 18 Furnace core tube 19 Motor 20 Mobile device 21 Radiation thermometer 22 Temperature observation window 23 Control computer 24 Heating power supply 25 Magnetron 26 Gas cylinder 27 Valve 28 Flow regulator 29 Vacuum pump 30 Screen 31　Sample operation door 32 Atmosphere control device 33 Pulley 34 Belt 35 Motor

Claims (7)

[Claims] 1. An ellipsoidal mirror having an ellipsoidal reflective surface on the inside, and two sample insertion holes provided at the second focal point side end thereof centered on a perpendicular to the long axis passing through the second focal point. , an egg-shaped plasma lamp placed at the first focal point of the ellipsoidal mirror, and a radio wave shielding plate that accommodates the egg-shaped plasma lamp and is attached to the inner surface of the ellipsoidal mirror at its first focal point side end. What is claimed is: 1. A soaking plasma image heating device comprising: a cavity resonator formed by the above-described method; and a high-frequency oscillator for injecting microwave power into the cavity resonator. 2. An ellipsoidal mirror having an ellipsoidal reflective surface on the inside and one sample insertion hole provided at the end on the second focal point side centered on the long axis; 1st
A cavity resonance formed by an egg-shaped plasma lamp placed at the focal point and a radio wave shielding plate that accommodates the egg-shaped plasma lamp and is attached to the inner surface of the ellipsoidal mirror at the end on the first focal point side. and a high-frequency oscillator for injecting microwave power into the cavity resonator. 3. The soaked plasma image heating device according to claim 1, wherein the cavity resonator is formed into a bowl shape or a cup shape. 4. A rotation device that grips and rotates the sample at the end of the sample inserted into the sample insertion hole in the short axis direction, a moving device that moves the sample in the short axis direction, and a reactor core tube that stores the sample. and an atmosphere control device connected to the reactor core tube, a radiation thermometer placed facing the sample, and a control device connected to the radiation thermometer and a heating power source. The soaked plasma image heating device according to claim 1. 5. A rotating device that grips and rotates the sample at the end of the sample inserted into the sample insertion hole in the longitudinal direction, a moving device that moves the sample in the longitudinal direction, and a reactor core tube that stores the sample. and an atmosphere control device connected to the reactor core tube, a radiation thermometer placed facing the sample, and a control device connected to the radiation thermometer and a heating power source. The soaking plasma image heating device according to claim 2. 6. A rotation device that grips and rotates the sample at the end of the sample inserted into the sample insertion hole in the short axis direction, a moving device that moves the sample in the short axis direction, and a reactor core tube that stores the sample. and an atmosphere control device connected to this reactor core tube, a radiation thermometer placed facing the sample, a control device to which this radiation thermometer and heating power source are connected, and an egg-shaped plasma lamp. The soaking plasma image heating apparatus according to claim 1, further comprising a rotating rotating device. 7. A rotating device that grips and rotates the sample at the end of the sample inserted into the sample insertion hole in the longitudinal direction, a moving device that moves the sample in the longitudinal direction, and a reactor core tube that houses the sample. , an atmosphere connection device connected to this reactor core tube, a radiation thermometer placed facing the sample, a control device to which this radiation thermometer and heating power source are connected, and an egg-shaped plasma lamp that supports and rotates. 3. The soaking plasma image heating apparatus according to claim 2, further comprising a rotating device for heating the image.