JP2012142248A - Laser ion generator - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a low-cost laser ion generator capable of transmitting an ion of high valence and measuring an ion speed distribution of required valence and the number of ions without an accelerator.SOLUTION: The laser ion generator comprises: a pulse laser light source 11 which generates a laser beam; plasma generation means 15 which generates a plasma by irradiating a material 14 with the laser beam generated from the pulse laser light source 11; ion extraction means 16 which extracts a heavy particle ion in the generated plasma with an electric field; ion speed measurement means 18 which measures an ion speed distribution of the extracted heavy particle ion; and ion speed distribution calculation means which calculates and outputs an ion speed distribution and the number of ions of each valence from the ion speed measurement means.

Description

  The present invention relates to a heavy ion beam therapy technique, and more particularly, to a laser ion generator capable of stably providing ions with a required valence and the number of ions using pulsed laser light.

  In recent years, there is an ion generator using microwave discharge as an ion generator used for heavy particle beam therapy. This ion generator is configured to extract ions in plasma generated by irradiating a target of a plasma generation target with laser light.

  As such an ion generating apparatus, an ion beam extracting apparatus for extracting a plasma generated by irradiating a plasma generating target in a laser ion source with a container-like voltage and making it enter an accelerator while maintaining the plasma state. (See Patent Document 1).

JP 2009-37704 A

  The ion source using the microwave discharge currently adopted has a low valence ion generation efficiency, so the generated plasma is ionized to some extent, accelerated by an accelerator, and then charged using a charge conversion device. Ions are generated. For this reason, even if the ion source itself is small, a plasma accelerator ionized to a certain extent, a charge exchange device, and the like are required, and the laser ion generator itself is increased in size and cost.

  In addition, an ion beam extraction device using laser light does not require an accelerator or a charge exchange device, but it is difficult to measure the number of ions generated for each valence in the ion generation unit, and the number of ions for each valence. When securing the above, there is a problem that the cost is high because the electric field and magnetic field of the accelerator are used.

  The present invention has been made in consideration of the above-described circumstances, can provide high-valence valence heavy particle ions, can measure ion valence and number of ions without an accelerator, and the apparatus itself An object is to provide a small and low-cost laser ion generator.

  In order to solve the above-described problems, a laser ion generator according to the present invention includes a pulsed laser light source for generating laser light, and plasma generating means for generating plasma by irradiating a substance with the laser light from the pulsed laser light source. An ion extracting means for extracting ions in the generated plasma by an electric field, an ion velocity measuring means for measuring the ion velocity distribution of the extracted heavy particle ions, and an ion velocity distribution of each valence from the ion velocity measuring means, It has an ion velocity distribution calculating means for calculating and outputting the number of ions.

  The laser ion generator of the present invention is capable of providing multivalent valence heavy particle ions and stably providing the necessary number of heavy particle ions and the number of ions without using an accelerator or load exchange device. Can do.

The block diagram of the laser ion generator which shows 1st Embodiment of this invention. The figure which shows the vacuum vessel, cylindrical container, and intermediate | middle container with which a laser ion generator is equipped. The figure which shows the example of the parallel displacement means with which the ion velocity measurement means of a laser ion generator is equipped. The figure which simplifies and shows the movement procedure of the substance installed in a vacuum vessel. The figure which shows an ion acceleration means. The block diagram of the laser ion generator which shows 2nd Embodiment of this invention. The block diagram of the laser ion generator which shows 3rd Embodiment of this invention.

  Embodiments according to the present invention will be described below with reference to the accompanying drawings.

[First Embodiment]
1 and 2 show a first embodiment of a laser ion generator 10 according to the present invention.

  The laser ion generator 10 includes a pulse laser light source 11, an optical path adjusting unit 12 that adjusts an optical path of laser light output from the pulse laser light source 11, and a vacuum container 13 that is kept in a vacuum environment and sealed. Plasma generating means 15 for generating plasma by irradiating a plasma generation target material 14 with pulsed laser light, ion extracting means 16 for applying an electric field to the generated plasma and extracting heavy particle ions by Coulomb force, and ion extracting means Ion acceleration means 17 for accelerating the ions extracted by 16 by an electric field, ion velocity measurement means 18 for measuring the ion velocity distribution of heavy particle ions extracted and accelerated by the electric field, and the number of ions in the generated plasma. From the volume measuring means 19a, 19b to be measured, and the measured number of ions and ion velocity distribution, Calculates the on-valence and the number of ions, and an ion velocity distribution calculating means 20 for outputting.

  Further, an ion source 23 is constituted by a plasma generating means 15 for generating a plasma by irradiating a material 14 which is a plasma generation target with a pulse laser beam, and an ion extracting means 16 for extracting heavy particle ions from the generated plasma.

  A substance moving means 24 is provided in the vacuum container 13, and the substance 14 on the plasma generation target is installed so as to be movable or rotatable by the substance moving means 24. Further, the vacuum vessel 13 is provided with an incident window 25 in which the incident angle of the pulse laser beam is set to the Brewster angle, and the pulse laser beam from the pulse laser light source 11 is guided through the incident window 25. The entrance window 25 is made of a material such as quartz, fused quartz, or BK7 in order to suppress the reflection of the laser beam and transmit it. The pulse laser beam passing through the incident window 25 is focused and irradiated on the substance 14 in the vacuum vessel 13, and plasma containing heavy particle ions having a high valence is generated in the vacuum vessel 13 by laser excitation. In the case where pulsed laser light can be condensed from the pulsed laser light source 11 onto the substance 14 in the vacuum vessel 13 and directly irradiated, the optical path adjusting means 12 is not necessarily provided.

  A sleeve-like cylindrical container 27 extends from the vacuum container 13, and the cylindrical container 27 is provided with an intermediate container 28 having a width larger than the inner diameter of the cylindrical container 27 as shown in FIG. The vacuum vessel 13, the cylindrical vessel 27, and the intermediate vessel 28 are made of a material that is excellent in corrosion resistance and chemical resistance, such as stainless steel, and that emits less gas. Each container 13, 27, 28 is configured as a vacuum container so that a vacuum pump and a vacuum gauge (not shown) are attached and the inside of the container is maintained in a vacuum environment.

  Examples of the substance 14 installed in the vacuum vessel 13 of the plasma generating means 15 include carbon, silicon, helium, neon, argon, nitrogen, hydrogen and the like. The heavy particle ions present in the plasma of the substance 14 have a characteristic that the penetration depth in the body is determined by the energy, and the energy is suddenly released immediately before stopping. This phenomenon of heavy ion (heavy particle beam) is called black peak, and this phenomenon is used in heavy particle beam therapy.

  In other words, by using an accelerator called synchrotron to adjust the energy of heavy particle ions and stopping at the position of tumor cells, damage to normal cells from the body surface to tumor cells is reduced, and the target tumor It is possible to treat cells by acting heavy particle ions.

  Further, in the accelerator, the larger the valence of the ions, the stronger the influence of the electric field and magnetic field, and the higher the accelerating efficiency, the higher the valence of heavy particle ions suitable for tumor treatment.

On the other hand, the pulsed laser light source 11 is a pulsed laser that generates laser-excited plasma by irradiating a substance 14 that is a plasma generation target with laser light. _Two lasers, Q-switch YAG laser, etc. are applicable. Note that the transverse mode, longitudinal mode, polarization state, circular, elliptical, or rectangular beam shape of the pulse laser light source 11 can be appropriately selected.

  The ion extraction means 16 that draws out heavy particle ions, which are positive ions, by applying an electric field from the plasma generated by the plasma generation means 15 and acting on the Coulomb force, repels the electrons in the generated plasma by the Coulomb force. An electrode that generates an electric field for extracting ions, and an electrode such as a hollow disk electrode, a mesh electrode, or a parallel plate electrode is used. For example, a vacuum vessel 13 is grounded, and a negative cylindrical pulse voltage is applied to a hollow cylindrical electrode fixed to the vacuum vessel 13 by an insulator. After extracting the voltage, the voltage may be dropped during the time when ions pass through the electrode.

  The plasma generated on the surface of the substance 14 in the vacuum vessel 13 by laser irradiation is ionized on the assumption that it thermally expands, and ionization proceeds stepwise by the electrons generated along with the ionization. When the laser irradiation is completed, the plasma gradually cools. However, since ions and electrons continuously react in the plasma, the velocity distribution for each ion valence broadens. By repelling the electrons after the laser irradiation is completed, the reaction between useless electrons and ions can be suppressed, and the velocity distribution of heavy particle ions can be narrowed.

  The ion accelerating means 17 is a multi-stage electrode that generates an electric field that accelerates the heavy particle ions extracted by the ion extracting means 16, and an electrode such as a hollow disk electrode, a mesh electrode, or a parallel disk electrode is used as the electrode. Used. For example, the vacuum vessel 13 is grounded, the electrode is fixed to the vacuum vessel 13 with an insulator, and a pulse voltage shorter than the time during which heavy particle ions exist is applied between the electrodes in synchronization with the timing of passing through the electrodes. . The pulse voltage may be a positive voltage or a negative voltage. In the case of a positive voltage, the heavy particle ions are pushed out, and therefore, the voltage may be applied after the heavy particle ions pass through the electrode. In the case of a negative voltage, the voltage may be applied before passing through the electrode in order to extract heavy particle ions. Further, a positive voltage may be applied to the rear electrode of the electrode where heavy particle ions exist, and a negative voltage may be applied to the front electrode.

  The ion velocity measuring means 18 provided in the intermediate container 28 in the middle of the cylindrical container 27 is a means for measuring the velocity of heavy particle ions in the plasma generated by laser irradiation. The ion velocity measuring means 18 is composed of a Faraday cup or the like for measuring the value of the current flowing through the detector simultaneously with the ion velocity distribution obtained by synthesizing the ion velocity distribution of each valence. For example, in the Faraday cup, a metal conductor such as gold, platinum, copper, or nickel is used as a conductor member material that captures heavy particle ions in plasma.

  The parallel moving means 30 is a parallel moving means for moving the ion velocity measuring means 18 from the central axis of the vacuum vessel 13 in parallel to the material surface. A stepping motor, a servo motor or the like that can change the position of the ion velocity measuring means 18 from the outside. The motor drive mechanism is configured. The translation means 30 has a structure as shown in FIG. 3, for example. When adjusting the ion source 23, in order to detect heavy particle ions actually incident on the accelerator, the ion velocity measuring means 18 is installed in the interior 18a of the dotted line shown in FIG. In order to make heavy particle ions enter, it is installed on the outside 18b of the dotted line shown in FIG. The ion velocity measuring means 18 estimates the amount of ions incident on the accelerator from the distribution of heavy particle ions in the plasma.

  By the way, the volume measuring means 19a and 19b provided in the vacuum vessel 13 is a three-dimensional measuring means for measuring the volume of the irradiation mark formed by laser irradiation on the substance 14. For the volume measuring means 19a, 19b, a measuring method using laser light or ultrasonic waves is used. When laser light is used, a light cutting method, a moire method, a stereo vision method, or the like can be applied. When an ultrasonic wave is used, it can be applied by bonding to a fixed portion of the substance 14 or the like. The number of evaporated atoms can be estimated from the volume of the irradiation mark and the density of the substance 14. Most of the incident energy of the laser is used for heating and evaporation of the substance 14, and atoms are ionized by the energy used for evaporation from the incident energy.

  In the plasma, electrons gain energy by the thermal energy or electric field of the laser beam and become high energy, and the electrons with high energy react with neutral particles and heavy particle ions to increase the ion valence stepwise. To do. Therefore, by reducing the energy consumption for evaporating the substance, the temperature of electrons and heavy particle ions in the plasma is raised, and the production efficiency of high-valence and expensive ions is improved.

  The substance moving means 24 in the vacuum vessel 13 is a means for moving and rotating the substance 14 to secure a new irradiation surface. The substance moving unit 24 is configured by a motor driving mechanism such as a stepping motor or a servo motor that can control the movement and rotation from the outside. For example, it has a structure of a motor drive mechanism as shown in FIG. Since the plasma distribution generated by laser irradiation has a peak in the direction perpendicular to the substance 14, as the laser irradiation trace becomes deeper, it is deposited on the substance 14 and the number of generated ions decreases. Therefore, the ion generation amount can be kept constant by keeping the irradiation surface new. The timing of rotation is determined by each pulse of the laser, when the volume change measurable by the volume measuring means 19a, 19b falls below the threshold, or when the ion current value estimated by the ion velocity measuring means 18 falls below the threshold. It's okay.

  Moreover, the ion velocity distribution calculating means 20 shown in FIG. 1 is a means for calculating the number of generated ions. The ion velocity distribution calculating means 20 outputs the ion velocity calculating means 21 for calculating the ion velocity distribution obtained by the ion velocity measuring means 18 and the ion velocity distribution for each valence from the volume measuring means 19a, 19b, and the value. Output means 22. The ion velocity distribution calculating unit 20 includes, for example, an ion velocity calculating unit 21 that calculates an ion velocity distribution for each valence at an elapsed time, and an ion for calculating the number of ions from the ion velocity distribution for each valence. It is composed of a PC having a number calculation unit and an output unit for the value.

As the PC, a general-purpose PC such as a desktop PC, a laptop PC, or a notebook PC is used. The incident energy depends on the pulse laser light source 11, and the substance 14 is evaporated by the energy absorbed by the substance 14. The ionization degree X of the ion valence in the plasma is expressed by the saha equation as shown by the equation (1).

  As shown in equation (1), the ionization degree depends on the temperature T, density n, and ionization energy I of the plasma, but the thermal energy that determines the equilibrium temperature of the plasma is determined when the substance 14 evaporates from the laser energy. Since it depends on the value obtained by subtracting the evaporation energy, it is important to monitor the volume of the irradiation mark.

  In addition, the heavy particle ions in the plasma, immediately after the laser irradiation, the electrons expand in the same direction with thermal energy, but the mass of the electrons is about 1/1000 that of the heavy particle ions, and the expansion rate is small. 30 times or more. Therefore, the distribution of electrons spreads around the ion distribution, and an electric field is generated due to electrons outside the ion distribution and heavy particle ions. Due to this electric field, the heavy particle ions receive a force depending on the valence, so that the distribution of each ion current is divided.

Assuming a Maxwell-Boltzmann distribution, the time distribution of the ion current is expressed by Equation (2) by the distance L, the ion velocity v, the ion mass m, and the plasma temperature T.

Here, k _B is a Boltzmann constant. Since the distance L and the ion mass m are known, the ion velocity distribution for each valence is obtained by fitting using the Maxwell-Boltzmann distribution with the ion velocity v and the plasma temperature T as parameters, and the ion velocity distribution for each valence. Can calculate the number of ions for each valence.

  The ion distribution in the plasma has a substantially fixed distribution. By measuring the spatial distribution by changing the position of the ion velocity measuring means 18 in advance, the number of ions incident on the accelerator from the location of the arbitrary ion velocity measuring means 18, It is possible to estimate the total number of ions.

(Operation of the first embodiment)
An ion beam for heavy ion beam therapy needs to have a high ion valence and a sufficient number of ions. Since the valence of heavy particle ions generated by the ion source 23 has a positive correlation with the power density of the laser light, it is preferable that the energy loss of the laser light from the pulse laser light source 11 is small.

  The laser light generated from the pulsed laser light source 11 is incident on the vacuum container 13 through the incident window 25 provided with a coating suitable for the wavelength of the laser light, thereby irradiating the substance 14 while suppressing reflection of the laser light. When the laser beam is focused on the substance 14, laser ablation plasma is generated near the surface of the substance 14, and heavy particle ions and electrons in the plasma fly in a direction perpendicular to the surface of the substance 14.

  Ionization proceeds while the plasma temperature is high, but when the plasma temperature is low, heavy particle ions and electrons are combined and returned to the original atoms, so the ions in the plasma are stripped off using the ion extracting means 16 and The number of ions is secured by extracting the particle ions and suppressing the reaction between the heavy particle ions and the electrons. At the same time, a wasteful reaction between heavy particle ions and electrons can be prevented, so that the velocity distribution for each valence becomes narrow.

  The heavy particle ions from which electrons have been stripped fly in the cylindrical container 27 while having a speed difference for each valence. However, as the valence increases, the speed difference decreases, and for each valence due to the difference in speed distribution. Since it is difficult to evaluate the number of ions, the ion acceleration means 17 is used to increase the speed difference for each valence. Most of the heavy particle ions having a velocity difference for each valence enter the entrance of the accelerator and are used for treatment, but the heavy particle ions that do not enter the accelerator are converted using the translation means 30 in the intermediate container 28. The ion velocity is measured by the ion velocity measuring means 18 installed beside the accelerator entrance, and the ion valence and the number of products are measured using the ion velocity distribution calculating means 20 to constantly monitor the number of ions.

  In addition, the ion spatial distribution can be measured by changing the position of the ion velocity measuring means 18 and measuring the ion valence and the number of products by using the parallel moving means 30 when adjusting the ion source 23. It is possible to constantly estimate the ion spatial distribution, the current distribution obtained by the ion velocity measuring means 18 installed beside the accelerator entrance, and the number of ions incident on the accelerator from the ion velocity distribution calculating means 20.

  The number of generated ions decreases when the pulse laser beam is continuously focused on the substance 14 and is reduced. However, in order to prevent a decrease in the number of generated ions, the volume change is monitored by the three-dimensional measuring method of the volume measuring means 19a, 19b. Can be provided with a heavy particle ion beam having a stable valence by changing the irradiation surface of the substance to a new one by the substance moving means 24 when the value of the particle is below the threshold value.

  In addition, by constantly monitoring the number of ions, when the number of ions falls below a threshold value, the rotating means as the substance moving means 24 rotates the substance surface, or measures such as increasing the laser energy are taken. Thus, a stable number of heavy particle ion beams can be provided. On the other hand, if the number of heavy particle beam beams is insufficient in the treatment stage, the cause is mostly in the ion source 23 or the accelerator, but the ion source 23 is measured by means for measuring the number of ions before entering the accelerator. Quickly determine whether or not there is a cause.

(Effect of 1st Embodiment)
According to this embodiment, when providing multivalent valence ions, an accelerator and a charge exchange device are not required, and a necessary number of ions can be stably provided. In addition, since a certain ratio of the ion beam generated by the ion source 23 is lost until the energy is accelerated to a treatable energy, it is necessary to monitor whether the number of ions necessary for the treatment is maintained. The current microwave ion source uses an accelerator at the stage of ionization, so an accelerator was required to confirm the number of ions with the required valence. By constantly monitoring the number, the ion source 23 can be adjusted easily and accurately.

[Second Embodiment]
Next, a second embodiment of the laser ion generator will be described with reference to FIG.

  In describing the laser ion generating apparatus 10A of the second embodiment, the same components and functions as those of the laser ion generating apparatus 10 shown in the first embodiment are denoted by the same reference numerals, and redundant description or illustration is omitted. .

  A laser ion generator 10A shown in FIG. 6 includes a plurality of laser light paths, and generates a laser excitation plasma by condensing and irradiating a laser beam onto a substance 14 provided in the vacuum vessel 13 from the plurality of laser light paths. Means 15 are provided.

  The laser ion generator 10A includes a laser beam branching unit 35 that branches the laser beam from the pulse laser source 11 into a plurality of, for example, two, and the laser beam branching unit 35 inserted into the laser beam path from the pulse laser source 11. Inserting means 36, optical path adjusting means 38a, 38b for condensing and irradiating the branched laser light to the same position of the substance 14 as the plasma generation target installed in the vacuum vessel 13 from different directions, and changing the wavelength of the laser light Wavelength conversion means 39a, 39b for performing the operation, incident windows 25a, 25b for guiding the branched laser light into the vacuum vessel 13, and heavy particle ions in the laser-excited plasma generated by the laser light irradiation on the substance 14 are extracted. Ion extraction means 16, ion velocity measurement means 18 for measuring ion velocity in plasma, and pulsed laser light irradiation The volume measuring means 19a, 19b for observing the volume of the beam mark formed by this, the substance moving means 24 for moving and rotating the substance 14, the ion velocity distribution calculating means 20 for obtaining the ion valence and the number of ions, etc. The

  The laser beam branching unit 35 is an optical element for branching the laser beam from the short pulse laser beam into two or more, and a Vericle beam splitter, a cube beam splitter, or a plate beam splitter is used. The beam splitter may be coated with a broadband dielectric coating, a laser line non-polarizing coating, a broadband hybrid coating, or a polarizing coating.

  The insertion means 36 is means for inserting the laser beam branching means 35 into the laser light path from the short pulse laser light source 11, and is driven by a motor such as a stepping motor or servo motor capable of changing the position of the laser light branching means 35 from the outside. It consists of a mechanism.

  The laser light from the pulse laser light source 11 has a temporal spread, and laser-excited plasma is generated from the moment when the laser light is irradiated. During the irradiation of the laser beam, ionization proceeds and the electron density in the plasma increases. However, if it increases too much, the transmittance of the laser beam in the plasma deteriorates and the energy of the laser beam becomes difficult to be absorbed by the substance 14. It is necessary to control the density.

  By branching the laser beam into two or more and reducing the energy of one laser beam, the electron density in the plasma is reduced, scattering and reflection on the plasma surface are suppressed, and the loss of energy of the laser beam is reduced. Can be irradiated. By removing the laser beam branching means 35 from the laser light path from the short pulse laser light source 11 using the insertion means 36, a single optical path can be reproduced as in the first embodiment, and the number of ions is increased. A method may be selected.

  The optical path adjusting means 38 a and 38 b are configured by an optical system such as a reflecting mirror that irradiates the same position on the material 14 with the laser beam from the pulse laser light source 11 branched into a plurality of parts.

  Furthermore, the wavelength conversion means 39a and 39b are optical elements for converting the wavelength of the laser light. When the pulse laser light source 11 is, for example, a YAG laser, the wavelength may be converted into a harmonic using a nonlinear optical crystal.

The shorter the wavelength of the laser light, the greater the energy per photon, so that it is easily absorbed by the substance 14. Further, the diffraction limited condensing diameter d at the focal position of the lens as the condensing means (not shown) can be expressed by the equation (3).

  Since the shorter wavelength can reduce the diameter at the time of condensing, the energy density of the laser light incident on the substance 14 is improved.

(Operation of Second Embodiment)
Next, the operation of the laser ion generator will be described.

  A description overlapping with that of the first embodiment is omitted. The valence of heavy particle ions in the laser-excited plasma has a correlation with the equilibrium temperature and density of the plasma. In order to increase the equilibrium temperature, it is necessary to irradiate the substance 14 with a lot of energy. The laser light oscillated from the pulsed laser light source 11 is split into two or more laser beams using the laser beam branching means 35, and the branched laser beams are split on the substance 14 using the optical path adjusting means 38a and 38b. Adjust so that the same position can be illuminated from different directions.

  When the wavelengths of two or more laser beams whose laser beam paths are adjusted are converted to shorter wavelengths by the wavelength converting means 39a and 39b, the beam diameter can be reduced when condensing the laser beam, and the energy per photon can be reduced. Increases, the absorption rate of the substance 14 increases.

  In addition, by suppressing the reflection of the laser beam through a plurality of incident windows 25a and 25b that have been coated suitable for the wavelength of the laser beam, the electron density can be controlled without reducing the total irradiation energy, and the number of ions generated can be stabilized. And secure. Since the electron density depends on the properties of the substance 14 and the pulsed laser light source 11, there may be a case where there is no need for branching. The position where the laser beam branching unit 35 is installed is controlled by using the insertion unit 36, and a stable ion number is provided by selecting a method in which the number of ions is increased in the case of a single optical path and in the case of a plurality of optical paths. can do.

(Effect of 2nd Embodiment)
According to the laser ion generator 10A of the second embodiment, it is possible to improve the absorption rate of laser light regardless of the characteristics of the substance 14, and to secure a stable number of ions. In addition, when the amount of generated ions decreases due to the reflection of the laser beam by the plasma, it is possible to control the electron density in the plasma to suppress the reflection of the laser beam, and to suppress the energy loss of the laser beam and to stabilize the number of ions. Can be provided.

[Third Embodiment]
FIG. 7 shows a third embodiment of the laser ion generator.

  In describing the laser ion generating apparatus 10B of the third embodiment, the same reference numerals are given to the same configurations and operations as those of the laser ion generating apparatus 10 shown in the first embodiment, and overlapping description or illustration is omitted. .

  A laser ion generator 10B shown in FIG. 7 includes a plurality of pulsed laser light sources 11 and 11 in a plasma generating unit 15 that irradiates a substance 14 installed in a vacuum vessel 13 with laser light and generates laser-excited plasma. A plurality of optical path adjusting means (not shown) for adjusting a plurality of pulsed laser beams to irradiate the same point on the substance 14 at the same time, a plurality of wavelength converting units 39a and 39b for changing the wavelength of the laser beam, A plurality of incident windows 25a and 25b guided into the vacuum vessel 13, an ion extracting means 16 for extracting heavy particle ions in the generated plasma, an ion velocity measuring means 18 for measuring the ion velocity in the plasma, and a pulse laser Volume measuring means 19a, 19b for observing the volume of a beam mark formed by irradiating light, and a substance for moving and rotating the substance 14 A moving means 24, ionic valence consists ion velocity distribution calculating means 20 for determining the number of ions.

(Operation of the third embodiment)
A duplicate description with the laser ion generator 10 of the first embodiment is omitted. The optical path adjustment is performed so that the laser light from the plurality of pulse laser light sources 11 is irradiated to the same position on the substance 14 at the same timing using a plurality of optical path adjustment means. A plurality of adjusted laser beams are changed to a wavelength having a high absorption rate using a plurality of wavelength conversion means 39a and 39b, and vacuum is applied through a plurality of incident windows 25a and 25b provided with a coating suitable for the wavelengths of the plurality of laser beams. The light enters the substance 14 in the container 13.

  The laser ion generator 10B according to the third embodiment includes a plurality of pulse laser light sources 11 and 11 and can obtain high energy that cannot be obtained by a single pulse laser light source. Even when the energy is required, a stable number of ions can be ensured.

(Effect of the third embodiment)
According to the laser ion generator 10B of the third embodiment, since the total amount of energy incident on the substance can be increased as compared with the single pulse laser light source, the energy density is improved and a large energy is required for ionization. The number of ions can be stably provided for the substance 14 to be processed.

10, 10A, 10B Laser ion generator 11 Pulse laser light source 12 Optical path adjusting means 13 Vacuum vessel 14 Substance 15 Plasma generating means 16 Ion extraction means 17 Ion acceleration means 18 Ion velocity measuring means 19a, 19b Volume measuring means 20 Ion velocity distribution calculation Means 21 Ion velocity calculation means 22 Output means 23 Ion source 24 Mass transfer means 25, 25a, 25b Incident window 27 Cylindrical container 28 Intermediate container 30 Parallel movement means 31a, 31b Volume measurement means 35 Laser beam branching means 36 Insertion means 38a, 38b Optical path adjusting means 39a, 39b Wavelength converting means

Claims (10)

A pulsed laser light source for generating laser light;
Plasma generating means for generating plasma by irradiating a substance with laser light from the pulse laser light source;
Ion extraction means for extracting heavy particle ions in the generated plasma by an electric field;
An ion velocity measuring means for measuring the ion velocity distribution of the extracted heavy particle ions;
An ion velocity distribution calculating means for calculating and outputting an ion velocity distribution of each valence and the number of ions from the ion velocity measuring means. The laser ion generator of Claim 1 provided with the optical path adjustment means which adjusts the optical path of the laser beam irradiated from the said pulsed laser light source. The laser ion generator according to claim 1, wherein the ion velocity distribution calculating means includes volume measuring means for measuring the number of ions in the plasma. The laser ion generator according to claim 1, wherein the ion velocity measuring unit includes a parallel moving unit that moves in parallel with the surface of the substance. 2. The laser ion generator according to claim 1, wherein the ion extracting means is a multi-stage electrode provided with two or more between the substance and the ion velocity distribution calculating means. The laser ion generation apparatus according to claim 3, wherein the volume measuring unit includes a unit that measures a three-dimensional shape of the substance. The laser beam adjusting means is
Laser beam branching means for dividing the laser beam into a plurality of optical paths;
Inserting means for inserting the laser beam branching means into the laser light path from the pulse laser light source;
The laser ion generator according to claim 2, further comprising: a condensing unit that condenses the laser beam branched by the laser beam branching unit on the substance. The laser beam adjusting means is
Condensing means for condensing the laser light from the pulsed laser light source onto a substance;
The laser ion generator according to claim 2 or 7, comprising wavelength conversion means for converting the wavelength of the laser light. The laser ion generator according to claim 1, wherein the substance is installed in a vacuum vessel, and a substance moving means for moving or rotating the substance is provided. 9. The laser ion generator according to claim 1, wherein a plurality of the pulse laser light source, the condensing unit, and the wavelength converting unit are provided.

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