JP2009070586A - Plasma generation method, plasma generation device, cavity for plasma generation device, and measuring apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a plasma generation method and a plasma generation device in which laser beam-induced plasma of a high intensity and a large capacity can be generated under an easy control in atmospheric pressure by using a low-output laser beam. <P>SOLUTION: Light emitted from a light source 101 is condensed on a material P to which energy more than a breakdown threshold value is given, and electromagnetic waves are emitted by an electromagnetic wave oscillator 105 toward a light condensed position, and energy is supplied to the plasma generated by the light irradiation. The light and the electromagnetic wave are controlled in synchronization, and an irradiation timing of the light and an emitting timing of the electromagnetic wave are controlled. As a result, electrons are accelerated and the electrons collide with neutral atoms and the neutral atoms are ionized. The electrons generated by ionization work similarly and the ionization continues in an avalanche. As a result, an energy density in the plasma becomes high and the plasma is expanded. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a plasma generation method and a plasma generation apparatus, and more particularly to a plasma generation method, a plasma generation apparatus, a cavity for a plasma generation apparatus, and a measurement apparatus that generate plasma by irradiating light such as laser light.

  Patent Document 1 describes that breakdown plasma can be generated by irradiating a sample with light having energy equal to or higher than a breakdown threshold.

  Patent Document 2 describes a technique for measuring light emission from plasma when a sample is focused and irradiated with laser light to generate plasma. That is, Patent Document 2 describes that induced fluorescence is generated by irradiating laser light having a wavelength specific to a sample element with good timing, and the induced fluorescence is measured and analyzed by an optical measuring instrument.

  In the technology for generating plasma using these laser beams, it is possible to generate plasma with high emission intensity by using high-power laser beams or by irradiating a sample with laser beams multiple times. Has been tried.

JP-A-1-259240 JP-A-11-2604

  By the way, in the conventional plasma generating apparatus described above, it is difficult to generate a large volume of high radiation intensity plasma. If a high-power laser beam is used, the volume of the generated plasma can be increased. However, the high-power laser beam is difficult to control the condensing position and is not easy to handle. In addition, high-power laser light is severely worn by the optical system used for condensing light and the like.

  In the conventional plasma generating apparatus, it is difficult to sustain the generated plasma for a long time. The laser beam induced breakdown plasma generated by one laser beam irradiation has a very short duration.

  Here, it is conceivable to obtain a desired plasma by irradiating a laser beam a plurality of times with good timing. However, in order to irradiate a laser beam a plurality of times with a good timing, extremely complicated control is necessary and difficult. Further, when the laser beam is irradiated a plurality of times, the position of the plasma generated by the subsequent laser beam irradiation is shifted due to the influence of the energy field and the plasma generated by the previous laser beam irradiation. . For this reason, the feature of plasma generation using laser light that the generation position of plasma can be controlled with high accuracy is impaired.

  Therefore, when using a plasma generation method using a laser especially for analysis, etc., if the output is increased to obtain a sufficient amount of light, a situation in which the target is damaged due to the high energy of the laser occurs. If damage is to be minimized, a situation may occur in which a sufficient amount of light cannot be obtained for analysis. Therefore, application to analysis of organic compounds such as proteins and biological tissues, or analysis of chemically unstable explosives is difficult.

  Therefore, the present invention has been made in view of the above-described circumstances, and can easily control high-intensity and large-volume laser light-induced plasma using low-power laser light under atmospheric pressure. An object of the present invention is to provide a plasma generation method and a plasma generation apparatus which can be realized by the above.

  It is another object of the present invention to provide a plasma generating device cavity suitable for configuring such a plasma generating device and a measuring device configured using such a plasma generating device.

  In order to solve the above-described problems and achieve the object, a plasma generation method according to the present invention has the following configuration.

[Configuration 1]
A first step of condensing light emitted from a light source and applying energy above a breakdown threshold to a substance existing at a position where the light is condensed; and a first step of emitting electromagnetic waves toward the light condensing position A second step of supplying energy to a region in the vicinity of the plasma generated by the step of controlling light and electromagnetic waves synchronously to control light irradiation timing and electromagnetic wave emission timing Plasma generation method.

  In this plasma generation method, energy is supplied by electromagnetic waves to plasma generated by light irradiation. The supplied energy is mainly absorbed by electrons in the plasma. As a result, electrons are accelerated, and the electrons collide with neutral atoms, whereby neutral atoms are ionized. Since electrons generated by ionization work in the same way, ionization proceeds in an avalanche manner. This increases the energy density in the plasma and expands the plasma.

[Configuration 2]
In the plasma generation method having the configuration 1, the light emitted from the light source is laser light.

[Configuration 3]
In the plasma generation method having Configuration 1 or Configuration 2, the electromagnetic wave is a microwave pulse.

  The plasma generation apparatus according to the present invention has any one of the following configurations.

[Configuration 4]
A light source that emits light, a condensing optical system that condenses the light emitted from the light source, an electromagnetic wave oscillator that oscillates electromagnetic waves, and a plasma generated by light irradiation by a substance that exists at the position where the light is collected An antenna that emits an electromagnetic wave toward the antenna and a control device that controls the electromagnetic wave oscillator, and the control device controls the light and the electromagnetic wave synchronously to control the irradiation timing of the light and the emission timing of the electromagnetic wave It is characterized by this.

  In this plasma generation apparatus, energy is supplied by electromagnetic waves to plasma generated by light irradiation. The supplied energy is mainly absorbed by electrons in the plasma. As a result, electrons are accelerated, and the electrons collide with neutral atoms, whereby neutral atoms are ionized. Since electrons generated by ionization work in the same way, ionization proceeds in an avalanche manner. This increases the energy density in the plasma and expands the plasma.

[Configuration 5]
A light source that emits light, an optical fiber that guides the light emitted from the light source, a condensing optical system that condenses the light guided by the optical fiber, an electromagnetic wave oscillator that oscillates electromagnetic waves, and a position where the light is collected And an antenna that radiates electromagnetic waves toward the plasma generated by the irradiation of light with a substance that emits light, and a control device that controls the electromagnetic wave oscillator. The control device controls the light and electromagnetic waves synchronously, The irradiation timing and the emission timing of electromagnetic waves are controlled.

[Configuration 6]
A light source that emits light, an optical fiber that guides the light emitted from the light source and irradiates the affected part in the living body, an electromagnetic wave oscillator that oscillates an electromagnetic wave having an energy density that does not cause tissue destruction of the living body, and the vicinity of the affected part by light irradiation An antenna that radiates electromagnetic waves from outside the living body toward the vicinity of the generated plasma and a control device that controls the electromagnetic wave oscillator, and the control device synchronously controls the light and the electromagnetic waves to irradiate light. And the radiation timing of electromagnetic waves are controlled.

  In this plasma generation apparatus, energy is supplied to the plasma generated in the affected area by light irradiation by electromagnetic waves without causing tissue destruction of the living body. The supplied energy is mainly absorbed by electrons in the plasma. As a result, electrons are accelerated, and the electrons collide with neutral atoms, whereby neutral atoms are ionized. Since electrons generated by ionization work in the same way, ionization proceeds in an avalanche manner. This increases the energy density in the plasma and expands the plasma.

[Configuration 7]
In the plasma generating apparatus having the configuration 6, the optical fiber and the antenna are integrally configured.

[Configuration 8]
In the plasma generation device having any one of Configurations 4 to 7, the light emitted from the light source is laser light.

[Configuration 9]
In the plasma generation device having any one of Configurations 4 to 8, the electromagnetic wave is a microwave pulse.

[Configuration 10]
In the plasma generating apparatus having the configuration 9, the electromagnetic wave oscillator oscillates a microwave pulse by being supplied with power from a pulse power source controlled by a control device.

[Configuration 11]
In the plasma generation apparatus having the configuration 9 or the configuration 10, the microwave pulse oscillated by the microwave oscillator is transmitted to the antenna through the microwave transmission system.

  In this plasma generation apparatus, it is possible to generate plasma even in a region where microwave pulses cannot be directly emitted.

  And the cavity for plasma generators concerning the present invention has the following composition.

[Configuration 12]
A plasma generation device cavity that covers a plasma generation region in a plasma generation device having any one of Configurations 4 to 11, and is a strong electric field that is made of a conductor and contains an antenna and is formed by electromagnetic waves radiated from the antenna. A main cylinder having an incident window into which light is incident at a position facing the area of the main body, and a side cylinder connected to the main cylinder at the periphery of the incident window and extending toward the outer side of the main cylinder, The tube has a length determined according to the wavelength of the electromagnetic wave radiated from the antenna.

  The measuring device according to the present invention has the following configuration.

[Configuration 13]
A plasma generation device having any one of Configurations 4 to 11 and measurement means for measuring light emitted from plasma generated by the plasma generation device are provided.

  In the plasma generation method according to the present invention, energy can be supplied to the plasma generated by light irradiation by electromagnetic waves. The supplied energy is mainly absorbed by electrons in the plasma. As a result, electrons are accelerated, and the electrons collide with neutral atoms, whereby neutral atoms are ionized. Since electrons generated by ionization work in the same way, ionization proceeds in an avalanche manner. Thereby, the energy density in plasma can be made high and plasma can be expanded.

  That is, in this plasma generation method, it is possible to obtain a plasma having a large volume and a high emission intensity that cannot be obtained without using high-power light without using high-power light.

  In this plasma generation method, plasma can be generated satisfactorily by using laser light as the light emitted from the light source.

  In the plasma generating apparatus according to the present invention, energy is supplied by electromagnetic waves to plasma generated by light irradiation. The supplied energy is mainly absorbed by electrons in the plasma. As a result, electrons are accelerated, and the electrons collide with neutral atoms, whereby neutral atoms are ionized. Since electrons generated by ionization work in the same way, ionization proceeds in an avalanche manner. This increases the energy density in the plasma and expands the plasma.

  That is, in this plasma generation apparatus, a plasma having a large volume and a strong emission intensity that could not be obtained without using high-power light can be obtained without using high-power light.

  In the plasma generation apparatus according to the present invention, energy is supplied by electromagnetic waves to the plasma generated in the affected area by light irradiation without causing tissue destruction of the living body. The supplied energy is mainly absorbed by electrons in the plasma. As a result, electrons are accelerated, and the electrons collide with neutral atoms, whereby neutral atoms are ionized. Since electrons generated by ionization work in the same way, ionization proceeds in an avalanche manner. This increases the energy density in the plasma and expands the plasma.

  That is, in this plasma generation apparatus, plasma can be generated only in the affected area, and OH radicals can be generated from the cellular water near the affected area. And by this OH radical, only the affected tissue can be destroyed accurately and safely.

  In this plasma generator, plasma can be generated satisfactorily by using laser light as the light emitted from the light source.

  In the plasma generation apparatus according to the present invention, the electromagnetic wave oscillator can be installed at a location away from the plasma generation point, and plasma can be generated even in an area where electromagnetic waves cannot be directly emitted.

  That is, the present invention provides a plasma generation method and a plasma generation apparatus that can realize high-intensity and large-volume photoinduced plasma under atmospheric pressure by easy control using low-power light. It is something that can be done.

  In the cavity for a plasma generating apparatus according to the present invention, a main cylinder having an entrance window through which light is incident at a position facing a region of a strong electric field formed of a conductor and containing an antenna and formed by electromagnetic waves radiated from the antenna. And a side tube connected to the main tube at the periphery of the incident window and extending toward the outer side of the main tube, the side tube being determined according to the wavelength of the electromagnetic wave radiated from the antenna Since it has a length, it can resonate inside the electromagnetic wave and form a standing wave without leaking the electromagnetic wave to the outside.

  The measurement device according to the present invention includes a plasma generation device and measurement means for measuring light emitted from the plasma generated by the plasma generation device, and therefore uses the plasma generated by the plasma generation device. LIBS measurement can be performed.

[First Embodiment]
FIG. 1 is a block diagram showing a configuration in a first embodiment of a plasma generation apparatus according to the present invention for executing a plasma generation method according to the present invention.

  As shown in FIG. 1, the plasma generating apparatus according to the present invention includes a laser light source 101 that generates light for generating plasma. Laser light emitted from the laser light source 101 enters the condensing optical system 102. The condensing optical system 102 condenses the laser light emitted from the laser light source 101 on the plasma generation region P.

  As the laser light source 101, for example, an Nd: YAG laser light source can be used. A convex lens can be used as the condensing optical system 102.

  The plasma generation apparatus includes a microwave oscillator 105 that is an electromagnetic wave oscillator that oscillates a microwave pulse, and an antenna 106 that radiates the microwave pulse oscillated by the microwave oscillator 105 toward the plasma generation region P. Yes. That is, the antenna 106 is disposed toward the focal position of the condensing optical system 102. A microwave pulse is radiated | emitted toward the plasma produced | generated in the plasma production area | region P by irradiation of the laser beam. The microwave oscillator 105 is powered by a pulse power source 104 and operates.

  As the microwave oscillator 105, for example, a magnetron that oscillates at 2.45 GHz can be used. The antenna 106 is an antenna having a sufficient gain with respect to the microwave oscillated by the microwave oscillator 105. For example, a 3/4 wavelength monopole antenna can be used. As the pulse power supply 104, an inverter power supply device can be used.

  The plasma generation apparatus includes a control device 103 that controls the irradiation timing of laser light and the emission timing of microwaves. The laser light source 101 is controlled by a control device to emit laser light. The pulse power source 104 supplies power to the microwave oscillator 105 in accordance with a control signal from the control device, and oscillates the microwave. As this control device 103, a two-channel pulse generator can be used.

  In this plasma generation apparatus, the output of the laser light generated by the laser light source 101 is such that when the laser light is converged by the condensing optical system 102, the energy at the focal point is equal to or higher than the breakdown threshold of the substance present at the focal point. It becomes density. That is, it is an output necessary for the substance existing at the focal point to be converted into plasma by the laser beam.

  The microwave radiation means including the pulse power source 104, the microwave oscillator 105, and the antenna 106 has a predetermined value in the vicinity of a plasma generation region P (hereinafter referred to as a “breakdown region”) where plasma is generated by laser light. A region having the above electric field strength (hereinafter referred to as “strong electric field region”) is formed. This predetermined value means that when the condition that electrons are introduced into the strong electric field region is satisfied, the kinetic energy is supplied to the electrons so that the electrons collide with the substance existing in the strong electric field region and ionize the substance. The electric field strength required to In addition, the energy density of the strong electric field region is less than the energy density necessary for causing a dielectric breakdown in a substance existing in the strong electric field region.

  The strong electric field region includes any point in the space where electrons generated by the breakdown can reach, at a distance from the breakdown region. Desirably, the strong electric field region overlaps the breakdown region or includes the breakdown region itself. This is because, as shown in [Operation Example 2] to be described later, the plasma generated in the breakdown region can absorb the microwave energy to promote the growth and expansion of the plasma.

  At the latest, the microwave radiation means will not be able to emit electrons by the microwave radiation until the end of the period in which electrons generated by the breakdown due to laser light move to the region that should become a strong electric field region and do not recombine. Achieve formation of strong electric field region. However, it is desirable that the formation start time of the strong electric field region be before the disappearance time of the plasma generated only by the laser light in the breakdown region. This is because, as shown in [Operation Example 2], which will be described later, the plasma generated in the breakdown region can absorb the microwave energy to promote the growth and expansion of the plasma. The microwave emission may be started before the irradiation time of the laser beam.

  The time difference between the time at which the control device 103 generates laser light from the laser light source 101 and the time at which the control device 103 issues a command to the pulse power supply 104 to generate the microwave pulse is the condition regarding the above-described time and the plasma device. It can be determined as appropriate based on the time constant generated.

  The time constant is a delay in the start-up time of the optical plasma generating means composed of the laser light source 101 and the condensing optical system 102, a time required for breakdown by the laser light, a delay in the start-up time of the microwave radiating means, and a microwave oscillator For example, the rise time of oscillation.

[Operation example 1]
In the following operation example 1, plasma generation using microwave energy is performed in response to electrons generated by breakdown using laser light.

  In this operation example 1, when the operation is started, the control device 103 gives a command to the laser light source 101. The laser light source 101 starts generating laser light in response to this command. The generated laser light is focused on the focal point by the condensing optical system 102. At the focus, the energy density increases and reaches the breakdown threshold of the material present at the focus. When the breakdown threshold is reached, the substance ionizes due to the collision between the substance present at the focal point and the photon.

  Through the series of operations described above, plasma is generated using a material present in the breakdown region as a raw material. When plasma is generated at the focal point, electrons due to the plasma move to the surroundings. The moved electrons reach a region that becomes a strong electric field region.

  The control device 103 gives a command to the pulse power supply 104 with the above time difference with respect to the command to the laser light source 101. The pulse power supply 104 starts supplying power to the microwave oscillator 105 in response to this command. The microwave oscillator 105 oscillates upon receiving power and generates microwaves. The generated microwave is radiated from the antenna 106. A strong electric field region is formed in a time zone in which electrons reach a region where electrons and the like become a strong electric field region due to emitted microwaves.

  When electrons exist in the strong electric field region, the electrons gain energy from the microwave and accelerate, collide with a substance existing in the strong electric field region, and ionize the substance. As a result, plasma is formed using a material present in the strong electric field region as a raw material. Electrons resulting from this plasma gain energy from microwaves, accelerate, collide with surrounding materials, and ionize the materials. Due to this collision, ionization, and electron acceleration (so-called electron avalanche), the strong electric field region and the surrounding material are turned into plasma. As a result, the plasma grows and expands.

  In this operation example, since the frequency of the laser light is higher than the frequency of the microwave, the plasma generated by the laser breakdown may cause the cutoff of the microwave. In other words, when the laser beam output is large and the region that becomes the strong electric field region is close to the plasma generated by the breakdown due to the laser, the plasma totally reflects the microwave while the electron density of the region that becomes the strong electric field region is high. There are things to do. In such a case, the microwave oscillation start timing may be adjusted so that the strong electric field region is formed after the electron density of plasma generated by breakdown is reduced and the cut-off is not generated.

  In this operation example, if the intensity of the laser is sufficiently high, a shock wave generated by breakdown can trigger an avalanche in a strong electric field region. In such a case, instead of the arrival time of electrons in the strong electric field region, the microwave emission start time may be set based on the arrival time of the shock wave in the strong electric field region.

[Operation example 2]
In the operation example 2 shown below, microwave energy is absorbed in plasma generated by breakdown using laser light, and thus plasma generated in the breakdown region is expanded. In the second operation example, as described above, the strong electric field region overlaps the breakdown region or includes the breakdown region itself. Further, in this operation example 2, the microwave emission is started before the irradiation time of the laser beam, and the formation start time of the strong electric field region is before the disappearance time of the plasma generated only by the laser beam in the breakdown region. .

  In this operation example 2, when the operation is started and the control device 103 gives a command to the pulse power source 104, the microwave radiating means including the pulse power source 104, the microwave oscillator 105, and the antenna 106 radiates microwaves. A strong electric field region is formed around the breakdown region by the emitted microwave, and the microwave generated by the breakdown is irradiated with the microwave.

  Plasma generated by breakdown absorbs microwave energy. Due to the absorbed energy, electrons in the plasma gain energy and are accelerated. With the acceleration of electrons due to this energy absorption, an electron avalanche occurs in the peripheral region of the plasma, and the plasma expands.

[Effects of the present embodiment]
In this plasma generation apparatus, the generation position and timing of plasma can be easily controlled by using laser light, and a plasma with a large volume and high radiation intensity can be obtained by microwave assist. That is, a large volume and high radiation intensity plasma can be easily generated at a desired position and timing.

  By generating plasma with laser light, a large number of electrons can be supplied to the strong electric field region. For this reason, it is easier to start plasma generation and generate an electron avalanche in a strong electric field region than conventional microwave plasma generation methods triggered by stored electrons.

  Therefore, in this plasma generation apparatus, a large-scale plasma can be efficiently obtained as compared with the conventional microwave plasma generation method. Further, even when the output of the laser beam is small and the volume of the plasma generated by the breakdown by the laser beam is small, the plasma can be expanded and grown by the microwave. This contributes to energy saving, miniaturization, and simplification.

[Effects of using laser light]
According to the present embodiment, breakdown that triggers plasma generation is performed by laser light irradiation. This has the following desirable effects in addition to the aforementioned effects. In other words, the probability that breakdown is induced by laser light depends on the collision probability between the photon and the plasma source material. Therefore, as long as light transmission efficiency in the optical path to the focal point is secured, high pressure and high density Plasma generation in an atmosphere is easy. Further, as long as the light transmission efficiency in the optical path to the focal point is ensured, plasma can be generated without installing an electrode or the like in the vicinity of the plasma generation region. This contributes to the improvement of the plasma generation position selectivity and the reduction of plasma contamination.

  Further, according to the present embodiment, an Nd: YAG laser light source is used as the laser light source 101. Since the Nd: YAG laser light is not easily absorbed by water and has a high depth of penetration into a biological tissue or the like containing a lot of water, breakdown can be caused in the deep part of an object containing a lot of water. As a result of this breakdown, it becomes possible to generate a large-scale plasma in the deep part of an object containing a lot of moisture.

[Effects of using microwaves]
According to the present embodiment, the plasma is expanded by microwave radiation. This has the following desirable effects in addition to the aforementioned effects. That is, it is possible to generate plasma with lower power than plasma generation by direct dielectric breakdown using microwaves.

  In addition, since the start and end of the microwave oscillation by the microwave oscillator are controlled by turning on the power by the pulse power source, no mechanical configuration is required for the control. Therefore, it is relatively easy to perform control in the time direction, such as repeated oscillation of microwaves, with a high time response. This contributes to intermittent plasma generation and the like.

  By using a magnetron that oscillates at 2.45 GHz as the microwave oscillator 105, a plasma generation apparatus can be manufactured at low cost. This is because a magnetron that oscillates at 2.45 GHz is used in home microwave ovens and is inexpensive. This contributes to the cost reduction of the plasma apparatus of the present embodiment. Magnetron has an extremely high energy conversion efficiency of about 80% from input electric power to microwaves. This contributes to higher efficiency and energy saving.

[Effects of using antenna]
By using an antenna, microwaves can be emitted toward a desired position. The range of spatial selection is wider than when microwaves are applied to opposing electrode pairs or applied to coils. Therefore, the degree of freedom in design increases.

[Modification of Embodiment 1]
The laser light-induced plasma is usually extinguished in a very short time, but in the present invention, the plasma maintenance time can be controlled by controlling the microwave emission time. Generation of thermal plasma is possible by making the generation time longer than the rise time of the plasma temperature.

  Since thermal plasma has a high energy density, the material can be heated to a high temperature in a short time, and can be used as a high-temperature heat source for chemical reactions that proceed only at high temperatures.

[Second Embodiment]
FIG. 2 is a perspective view showing a configuration in a second embodiment of the plasma generating apparatus according to the present invention for executing the plasma generating method according to the present invention.

  The plasma generating apparatus according to the present invention can be configured as an endoscope as shown in FIG. The endoscope includes a laser light source 201 that emits a laser beam for generating plasma. Laser light emitted from the laser light source 201 is guided to the condensing optical system 202 by the optical fiber 208 and is condensed by the condensing optical system 202.

  The endoscope includes a microwave oscillator 205 that oscillates microwaves and an antenna 206 that radiates microwaves toward plasma generated by laser light irradiation. Microwaves are transmitted from the microwave oscillator 205 to the antenna 206 by the microwave transmission system 207.

  The laser beam irradiation timing and the microwave emission timing are controlled by the control device 203 as in the above-described embodiment. A pulse power supply 204 that supplies power to the microwave oscillator 205 supplies power to the microwave oscillator 205 in accordance with a control signal from the control device.

  In this endoscope, laser light and microwaves are synchronously oscillated at an appropriate timing, and each is transmitted to the distal end 211 of the endoscope through the optical fiber 208 and the microwave transmission system 207, and at the distal end 211 of the endoscope. A plasma having an appropriate intensity can be generated.

  FIG. 3 is a perspective view showing the configuration of the distal end of the endoscope in the second embodiment of the plasma generating apparatus according to the present invention.

  As shown in FIG. 3, a condensing optical system 202 provided at the tip of the optical fiber 208 and an antenna 206 provided at the tip of the microwave transmission system 207 are installed at the tip 211 of the endoscope.

  In this endoscope, for example, in the treatment of cancer, an appropriate extremely local plasma is generated at the tip of the endoscope, thereby destroying only the cancer tissue without affecting the surrounding tissue. It is possible.

  Reference numeral 209 in FIG. 3 denotes an objective lens of a fiber scope (not shown) for performing observation or optical measurement of a region where plasma is formed. Via the objective lens 209, confirmation of the position where the plasma should be generated, observation of the generated plasma and optical measurement, and confirmation of the result of plasma generation can be performed. Reference numeral 210 in FIG. 3 denotes an illumination light. By irradiating light toward an area where plasma is generated using the illumination light 210, the above confirmation is facilitated.

[Third Embodiment]
The laser plasma generation apparatus of the present invention may control ON / OFF of the laser light by controlling the transmission of light from the light source to the focal point, instead of controlling the laser light source itself using the control device. .

  FIG. 4 shows the configuration of the plasma generating apparatus according to such an embodiment.

  In this plasma generation apparatus, the laser light source itself is not controlled using a control device, but the laser transmission is controlled from the light source to the focal point F, thereby controlling the laser ON / OFF. A plasma generation apparatus 300 according to the third embodiment shown in FIG. 4 has the same focusing optical system 102 and pulse power supply 104 as those of the plasma generation apparatus 100 (see FIG. 1) according to the first embodiment. A microwave oscillator 105 and an antenna 106.

  The plasma generation apparatus 300 further includes a laser apparatus 301 and a control apparatus 303 instead of the laser apparatus 101 and the control apparatus 103 of the plasma generation apparatus 100, respectively. The plasma generation apparatus 300 further includes a chopper 310 connected to the control apparatus 303.

  The chopper 310 is disposed on the laser device 310 side from the focal point F of the condensing optical system 102 on the path of the laser light emitted from the laser device 310. The chopper 310 may be arranged on the focal point F side with respect to the condensing optical system 102.

  In this embodiment mode, a continuous wave device can be used as the laser device 301. As the chopper 310, a mechanical chopper can be used.

  The control device 303 controls the start and end of generation of laser light according to a command to the laser device 301. However, the start and end of generation of laser light here are not synonymous with the start and end of irradiation of laser light to the focal point F. The control device 303 controls the start and end of the laser beam irradiation to the focal point F according to a command to the chopper 310. The microwave control by the control device 303 is the same as the operation by the control device 103 according to the first embodiment.

  The chopper 310 operates in accordance with a command from the control device 303 and selectively blocks and opens the light path from the laser device 301 to the focal point F.

[Effects of the present embodiment]
In the present embodiment, the plasma generation timing is determined by directly controlling the laser beam by blocking and opening the laser beam path. As a result, various timing controls can be realized more easily than controlling the drive of the laser device itself. The laser beam according to the present embodiment does not require a high-power laser beam similar to that of the first embodiment. Therefore, the wear of the chopper is small.

[Modification of Third Embodiment]
In this embodiment, the time of irradiation of the laser beam onto the focal point F is controlled using a chopper. However, by arranging various optical components in combination on the laser beam path, it is possible to control the time for plasma generation. It becomes possible to realize advanced control.

  For example, by arranging a prism such as a wedge prism on the optical path, the position of the breakdown region can be adjusted. It is also possible to scan the position of the breakdown region by changing the position or angle of the wedge prism or by using a rotating polygon mirror. Further, for example, by using a zoom lens or a varifocal lens as the condensing optical system, the position of the breakdown region in the traveling direction of the laser light can be adjusted. By combining these, it becomes possible to adjust the flake-down region to a desired position three-dimensionally. That is, it is possible to select a region in which high-density plasma is instantaneously generated by the laser from among the regions that generate plasma. Therefore, breakdown occurs in a region where high-density plasma is desired to be generated or a region where wear due to high-density plasma is allowed, and a region where relatively low-density plasma is generated can be formed around the breakdown. it can.

[Fourth Embodiment]
FIG. 5 is a block diagram showing a configuration in the fourth embodiment of the plasma generating apparatus according to the present invention for executing the plasma generating method according to the present invention.

  As shown in FIG. 5, the plasma generation apparatus according to the present invention may include a cavity 410 that covers the strong electric field region and the breakdown region. In this embodiment, the antenna 406 is disposed in the cavity 410, and the microwave is transmitted to the antenna 406 through the cavity 410.

  This cavity is a cavity having a microwave resonance structure, and it is desirable that a microwave does not leak and a laser beam introduction window for introducing a laser beam is provided. FIG. 6 shows a specific example of the cavity 410 in a partially sectional perspective view. The cavity 410 has a cylindrical side wall part 420 and a main cylinder 423 including a first end face wall 421 and a second end face wall 422 covering the end of the side wall part 420. The first end face wall 421 is provided with an opening 425, and the antenna 406 is installed in the opening. Microwaves are introduced into the cavity 410 through this portion.

  A plurality of locations (four locations in the example shown in FIG. 5) are opened in the side wall 420 of the main cylinder 423, and side cylinders 424A, 424B, 424C, and 424D that are open at both ends are respectively joined to the periphery of the opening. . A flange is provided at each end of the side cylinders 424A, 424B, 424C, and 424D opposite to the main cylinder 423. A pipe for introducing a plasma source material into the cavity 410 or a translucent member for an observation window (for example, a glass window or a quartz window) may be connected to the flange.

  The main cylinder 423 and the side cylinders 424A, 424B, 424C and 424D are all made of a conductor. Microwaves introduced into the cavity 410 and radiated from the antenna 406 are reflected by the wall surface of the main cylinder 423. The inner diameters of the side cylinders 424A, 424B, 424C and 424D are generally less than about ¼ of one wavelength of the microwave. The lengths of the side cylinders 424A, 424B, 424C, and 424D are approximately an odd multiple of 1/4 of one wavelength of the microwave. Therefore, the microwave does not leak out of the cavity 410 from the side cylinders 424A, 424B, 424C, and 424D. This microwave resonates in the cavity 410 to form a standing wave. A region corresponding to the antinode of the standing wave is a strong electric field region.

  Two of the side cylinders 424A, 424B, 424C, and 424D (the side cylinders 424A and 424B in the example shown in FIG. 5) are used as an introduction window and an emission window for laser light. The light incident on the cavity 410 from one side passes through the vicinity of the region corresponding to the antinode of the above-mentioned standing wave, and is opposed to be emitted out of the cavity 410 from the other. The cavity 410 is arranged so that laser light is incident from one of these two side cylinders and is focused near the antinode region in the cavity 410.

  About another side cylinder, you may arrange | position suitably according to a use. For example, the measurement of light emitted from a region where plasma is formed, the observation of the region, the injection of plasma raw material formed in the region, or the direct introduction of a plasma measurement sensor or the like. In the case of using a cylinder, it is desirable that the side cylinder for that purpose be arranged so that the region can face over the side cylinder.

  When such a cavity is used, the position of the strong electric field region can be determined at a predetermined position by microwave resonance. In addition, the resonance can efficiently form a strong electric field region. Furthermore, it is possible to achieve both prevention of electromagnetic wave leakage and introduction of laser light.

[Fifth Embodiment]
A measurement apparatus according to the present invention includes the above-described plasma generation apparatus and a measurement system of LIBS (Laser-Induced Breakdown Spectroscopy). The LIBS measurement system includes a light receiving optical system, a spectroscope, a light receiving element, a signal processing device, and a computing device.

  FIG. 7 shows a schematic configuration of the present embodiment. As shown in FIG. 7, this measurement apparatus includes a laser light source 101, a condensing optical system 102, a pulse power source 104, and a microwave oscillator 105 similar to those in the first embodiment. This apparatus further includes an antenna 406 and a cavity 410 similar to those of the fourth embodiment.

  In addition to the function of the control device 103 according to the first embodiment, this measurement device includes a control device 503 having a function of issuing a command signal in accordance with the measurement timing. For this control device 503, a pulse generator having three or more output channels can be used.

  In addition, this measuring apparatus has a waveguide 511 having an introduction end of a microwave from the microwave oscillator 105, an isolator / circulator 512, and a coaxial waveguide as a microwave transmission path from the microwave oscillator 105 to the antenna 406. A wave tube converter 513 and a coaxial cable 514 are provided.

  Further, this measuring apparatus includes a beam sampler 520 and a power meter 521A for measuring incident laser light, and a power meter 521B for measuring laser light emitted from the cavity 310, as a light receiving optical system among LIBS measuring systems. And a light receiving optical element 522 that receives light from the plasma through the side tube, and an optical fiber 523 that transmits the light received by the light receiving optical element 522.

  In addition, this measuring apparatus includes a spectroscope 524. As the spectroscope 524, any of the Zernitana type, the Eschel type, the type using a filter, and the other type can be used.

  In addition, this measuring device is connected as a light receiving element so as to receive a command signal related to the measurement timing from the control device 503 and light separated by the spectroscope 524, and an electric power corresponding to the light received in response to the command signal. An optical sensor 525 that outputs a signal is included. As the optical sensor 525, for example, a photomultiplier tube or an image sensor such as a CCD or a CMOS can be used.

  In addition, this measurement device is connected as a signal processing device so as to receive the outputs of the power meters 521A and 521B and the optical sensor 525, and captures signals from these connected devices, synchronization, A / D conversion, and A signal processor 526 that performs buffering and the like is provided. In addition, this apparatus includes a computer 527 connected to a signal processor 526 as an arithmetic unit. As the signal processor 526, for example, a DAQ, an interface board for data capture that can be connected to a computer, or the like can be used. The computer 527 performs a calculation for calculating a predetermined measurement value from the signal processed by the signal processor 526 in advance according to an executable program stored in the computer and outputs the result. The computer 527 can be realized by a computer system including general computer hardware, a program executable by the computer hardware, and data that can be read or written using the computer hardware and the program. The specific hardware configuration of this computer system and the operation of this computer system itself are well known. Therefore, the details are not described here.

[Effects of the present embodiment]
In this apparatus, LIBS measurement using plasma generated by the plasma generation apparatus and the plasma generation method according to the first embodiment or the fourth embodiment can be performed. Therefore, it is possible to realize the desirable actions and effects exhibited by the first embodiment or the fourth embodiment in the LIBS measurement.

[Modification of the present embodiment]
FIG. 6 is a partial cross-sectional perspective view showing the shape of the cavity in the fourth embodiment of the plasma generating apparatus according to the present invention.

  In the plasma generating apparatus according to the present invention, as shown in FIG. 6, the control method according to the third embodiment may be used for laser light timing control. Furthermore, a breakdown region position control method according to a modification of the third embodiment may be used. This makes it possible to perform measurement under measurement conditions in which the relationship between the position of the breakdown region and the position of the LIBS measurement target affects the purpose or result of the measurement. For example, LIBS measurement in a plasma region other than the breakdown region can be performed.

  Furthermore, if a target object is prepared in advance in the breakdown area, in addition to the object to be measured, the measurement target material can be measured without being directly worn by the laser beam. It can be performed.

  Note that a large number of LIBS measurement systems may be prepared, and measurement may be performed simultaneously or with a time difference using the many measurement systems. Moreover, you may make it measure about many points in the area | region where a plasma is produced | generated by these many measurement systems.

[Other variations, etc.]
In each of the embodiments described above, the plasma generation apparatus has a single laser light source. However, a plurality of laser light sources may be used. The plurality of laser light sources may each emit sufficient energy for breakdown. Further, one breakdown region may be formed by concentrating light from the plurality of laser light sources at one point.

  In addition to the Nd: YAG laser light source, other general solid laser light sources can be used as a light source for causing breakdown. In addition to a solid laser light source, a liquid laser light source, a gas laser light source, a semiconductor laser light source, or a free electron laser light source may be used. The wavelength band used for the laser light source may be any of infrared, visible, ultraviolet and X-ray bands. Moreover, you may make it adjust the magnitude | size of a breakdown area | region, a position, and an energy density by changing the wavelength range | band of these laser beams. You may use the light which combined the laser beam of multiple bands, or the light which changed the laser beam spatially or temporally over multiple bands.

  The light for causing breakdown is not limited to laser light. Light of a laser diode or a high-intensity light-emitting diode semiconductor light-emitting element, light of a general light source such as an electric lamp or a fluorescent lamp, or radiation light, fluorescence, phosphorescence, flame light, plasma light, sunlight, etc. Any kind of light and a light source therefor can be used as long as the light can be condensed at an energy density sufficient to cause breakdown. If a light source having a small and high luminance such as a high luminance light emitting diode is used, the device can be made smaller and lighter. This also contributes to an improvement in handling safety.

  In the above-described embodiment, the substance that is a raw material of plasma may be any form such as a solid, a liquid, a gas, an atom, and an ion.

  In the above-described embodiment, the convex lens is used as the condensing optical system, but the present invention is not limited to this. Any optical element that collects light using refraction, reflection, diffraction, or the like may be used. A plurality of optical elements may be combined to form one condensing optical system.

  As a combination of the light source and the condensing optical system, the light emitted from a plurality of light sources may be condensed in the breakdown region. In that case, the light source and the condensing optical system may be arranged in parallel or in series with the light introduced into the breakdown region.

  In the above-described embodiment, the magnetron is exemplified as the microwave oscillator, but the present invention is not limited to such a configuration. It may be a feedback oscillator, a replacement oscillator, or any other type of oscillator. Specifically, a semiconductor oscillator, a solid oscillator oscillator, a CR oscillator circuit, an LC oscillator circuit, a tuned oscillator, a multivibrator oscillator, a neon tube oscillator circuit, a relay oscillator circuit, or similar oscillators are also included. It can be used as a wave oscillator. The electromagnetic waves generated using these oscillators may be modulated using a multiplier, a mixer circuit, or the like. Alternatively, amplification may be performed using an amplifier.

  In the above-described embodiment, the 2.45 GHz band microwave is used, but the present invention is not limited to such a microwave. If a strong electric field region having an energy density sufficient to generate an electronic avalanche is formed upon breakdown, the frequency may be higher or lower than 2.45 GHz. For example, in the 2.4 GHz band, an oscillator and radio equipment used for short-range radio data communication can be used. In the 5 GHz band, an oscillator such as a fish finder and wireless equipment can be used. The position, shape, or volume of the strong electric field region may be changed by combining or selecting electromagnetic waves having a plurality of frequencies.

  In addition to the waveguide and / or the coaxial cable, a stripline line or the like may be used for microwave transmission. Further, a switching circuit, a distributor, an impedance adjusting stub, and the like may be provided on the transmission line.

  In the above-described embodiment, the 3/4 wavelength monopole antenna is exemplified as the antenna, but the present invention is not limited to such an embodiment. As the antenna, any of a balanced type, an unbalanced type (dipole antenna, loop antenna, etc.), and an aperture type (horn antenna, etc.) may be used. Alternatively, an antenna using electromagnetic wave reflection, diffraction, refraction, or the like may be used. A diversity antenna or an array antenna may be used.

  Further, since the electric field in the vicinity of the strong electric field region changes in the process of plasma generation / growth, the antenna arrangement, shape, effective length, or direction may be changed.

  The embodiment disclosed this time is merely an example, and the present invention is not limited to the above-described embodiment. The scope of the present invention is indicated by each claim in the claims after taking into account the description of the detailed description of the invention, and all modifications within the meaning and scope equivalent to the wording described therein are intended. Including.

It is a block diagram which shows the structure in 1st Embodiment of the plasma production apparatus which concerns on this invention which performs the plasma production method concerning this invention. It is a perspective view which shows the structure in 2nd Embodiment of the plasma production apparatus which concerns on this invention which performs the plasma production method concerning this invention. It is a perspective view which shows the structure of the front-end | tip of the endoscope in 2nd Embodiment of the plasma production apparatus concerning this invention. It is a block diagram which shows the structure in 3rd Embodiment of the plasma production apparatus which concerns on this invention which performs the plasma production method which concerns on this invention. It is a block diagram which shows the structure in 4th Embodiment of the plasma production apparatus which concerns on this invention which performs the plasma production method which concerns on this invention. It is a partial cross section perspective view which shows the shape of the cavity in 4th Embodiment of the plasma production apparatus concerning this invention. It is a block diagram which shows schematic structure of the plasma production apparatus and LIBS measurement system which concern on this invention which performs the plasma production method which concerns on this invention.

Explanation of symbols

101, 201 Laser light source 102, 202 Condensing optical system 103, 203, 303, 503 Controller 104, 204 Pulse power source 105, 205 Microwave oscillator 106, 206, 406 Antenna 207 Microwave transmission system 208 Optical fiber 310 Chopper 410 Cavity 511 Waveguide 512 Isolator / circulator 513 Coaxial waveguide converter 514 Coaxial cable 520 Beam sampler 521A, 521B Power meter 522 Light receiving optical system 523 Optical fiber 524 Spectrometer 525 Optical sensor 526 Signal amplifier 527 Computer

Claims (13)

A first step of condensing the light emitted from the light source and applying energy equal to or higher than a breakdown threshold to a substance existing at a position where the light is collected;
A second step of radiating electromagnetic waves toward the light condensing position and supplying energy to a region near the plasma generated by the first step;
The plasma generation method, wherein the light and the electromagnetic wave are controlled synchronously to control the irradiation timing of the light and the emission timing of the electromagnetic wave. The plasma generation method according to claim 1, wherein the light emitted from the light source is laser light. The plasma generation method according to claim 1, wherein the electromagnetic wave is a microwave pulse. A light source that emits light;
A condensing optical system for condensing the light emitted from the light source;
An electromagnetic wave oscillator that oscillates electromagnetic waves;
An antenna that radiates the electromagnetic wave toward the plasma generated by irradiation of the light with a substance present at a position where the light is collected;
A control device for controlling the electromagnetic wave oscillator,
The said control apparatus controls the said light and the said electromagnetic wave synchronously, and controls the irradiation timing of the said light, and the radiation | emission timing of the said electromagnetic wave. The plasma generation apparatus characterized by the above-mentioned. A light source that emits light;
An optical fiber for guiding the light emitted from the light source;
A condensing optical system for condensing the light guided by the optical fiber;
An electromagnetic wave oscillator that oscillates electromagnetic waves;
An antenna that radiates the electromagnetic wave toward the plasma generated by irradiation of the light with a substance present at a position where the light is collected;
A control device for controlling the electromagnetic wave oscillator,
The said control apparatus controls the said light and the said electromagnetic wave synchronously, and controls the irradiation timing of the said light, and the radiation | emission timing of the said electromagnetic wave. The plasma generation apparatus characterized by the above-mentioned. A light source that emits light;
An optical fiber that guides the light emitted from the light source and irradiates the vicinity of the affected area in the living body;
An electromagnetic wave oscillator that oscillates an electromagnetic wave of energy density that does not cause tissue destruction of the living body,
An antenna that radiates the electromagnetic waves from outside the living body toward the vicinity of the plasma generated in the vicinity of the affected area by the irradiation of the light;
A control device for controlling the electromagnetic wave oscillator,
The said control apparatus controls the said light and the said electromagnetic wave synchronously, and controls the irradiation timing of the said light, and the radiation | emission timing of the said electromagnetic wave. The plasma generation apparatus characterized by the above-mentioned. The plasma generating apparatus according to claim 6, wherein the optical fiber and the antenna are integrally formed. The light emitted from the light source is laser light. The plasma generation apparatus according to any one of claims 4 to 7, wherein the light is laser light. The plasma generation apparatus according to any one of claims 4 to 8, wherein the electromagnetic wave is a microwave pulse. The plasma generation apparatus according to claim 9, wherein the electromagnetic wave oscillator oscillates a microwave pulse by being supplied with power from a pulse power source controlled by the control device. The plasma generation apparatus according to claim 9 or 10, wherein the microwave pulse oscillated by the microwave oscillator is transmitted to the antenna via a microwave transmission system. A plasma generating device cavity that covers a plasma generation region in the plasma generating device according to any one of claims 4 to 11,
A main cylinder having an entrance window through which the light is incident at a position facing a region of a strong electric field made of a conductor, accommodating the antenna, and formed by an electromagnetic wave radiated from the antenna;
A side tube connected to the main tube at the periphery of the entrance window and extending toward the outer side of the main tube;
The side cylinder has a length determined according to the wavelength of electromagnetic waves radiated from the antenna. A plasma generation apparatus according to any one of claims 4 to 11,
A measuring apparatus comprising: a measuring unit that measures light emitted from plasma generated by the plasma generating apparatus.

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