JP5790992B2 - Side laser irradiator - Google Patents

Description

The present invention relates to a side laser irradiator that irradiates laser light from the side of a long target .

  A laser irradiator that performs processing, measurement, fusion, and the like by using laser light may be required to have a capability of irradiating an object with a plurality of laser lights with high resolution and high accuracy. For example, Patent Document 1 discloses a laser irradiator having a resolution that enables laser light to be irradiated with a time difference in femtosecond units. In fusion, in particular, such performance is often required.

  Development of nuclear fusion is being promoted as a technology that does not depend on fossil fuels for the generation of energy used for power generation. In such a fusion technology, a high-temperature and high-pressure plasma is generated, and a fusion reaction is induced while the generated plasma is held in one place. As one of the nuclear fusion methods, there is a method using the inertia of the plasma itself in order to keep the high temperature and high pressure plasma in one place. Such a method is called an “inertia confinement method”.

  In one of the inertial confinement fusions, implosion (compression) is caused by irradiating a member called “target” (or called “pellet” or “holum”) with high-intensity laser light. Thus, high-density (that is, high-temperature and high-pressure) plasma is generated by this implosion, and a nuclear fusion reaction is induced while the plasma remains at one place in the target. Such nuclear fusion is called “laser fusion”.

  A target used for laser fusion is generally formed in a cylindrical shape or a spherical shape, and a surface layer is provided on the outer periphery of such a target. By uniformly irradiating the outer peripheral surface of the surface layer with a plurality of laser beams, the target is rapidly heated, exploded, and activated. As a result, the inside of the target is about 100 times to the solid density. It will be implosion 10,000 times.

  An example of such laser fusion is disclosed in Patent Document 2. In Patent Document 2, high-energy particles are generated using high-intensity laser light, the target is irradiated with the high-energy particles, and a nuclear fusion reaction is induced at the target.

  In recent years, a method using ultra-high intensity and ultra-short pulse laser light (petawatt laser light) has been developed for laser fusion. This method is called a “fast ignition method”.

  An example of such a fast ignition type laser fusion is disclosed in Patent Document 3. In Patent Document 3, the target is provided with a main fuel portion formed in a hollow spherical shape, and the target is further provided with an ignition fuel portion formed in a hollow conical shape. An opening is formed in each of the tapered distal end of the ignition fuel portion and the proximal end facing the distal end. The ignition fuel part is attached to the main fuel part with its tip inserted into the main fuel part and close to the center of the main fuel part. The main fuel portion is provided with a fusion fuel layer around the hollow portion, and further, a first ablator layer is provided on the outer peripheral surface of the fusion fuel layer. An ignition fuel layer is provided so as to block the opening at the base end of the ignition fuel portion, and a second ablator layer is provided on the outer peripheral surface of the ignition fuel layer. In such a target, the main fuel layer is compressed by irradiating the outer peripheral surface of the main fuel portion with a petawatt laser beam, and another petawatt laser beam is applied to the opening at the base end of the ignition fuel portion. By irradiating, the ignition fuel layer is accelerated and collided with the compressed main fuel layer. As a result, energy is generated.

Japanese Patent No. 3796585 JP 2002-107494 A JP 2005-241462 A

  However, the laser irradiator of Patent Document 1 cannot irradiate a plurality of laser beams with high resolution and high accuracy so as to have a shorter time difference of femtoseconds to picoseconds. In particular, there has been no laser irradiator that can irradiate a plurality of laser beams moving at a high speed of femtoseconds to picoseconds with high resolution and high precision as used in laser fusion.

  Also, with regard to laser fusion, the conventional techniques as shown in Patent Document 2 and Patent Document 3 efficiently generate energy according to the necessity of continuously supplying a lot of energy as in power generation. Has not been achieved. Further, in laser fusion, a phenomenon in which fluid motion becomes unstable due to disturbance generated by unevenness generated at the boundary between fluids having different densities. This phenomenon is called “Rayleigh Taylor instability”. Due to the effects of “Rayleigh-Taylor instability”, conventional laser fusion technology makes it difficult to insulate and compress the interior of the target efficiently and uniformly. This is a big issue. Therefore, it is also desired to avoid such problems and propose a new laser fusion technique different from the conventional laser fusion technique.

The present invention has been made in view of such a situation, and an object thereof is to provide a side laser irradiator having a performance capable of irradiating a target with a plurality of laser beams with high resolution and high accuracy. It is an object of the present invention to provide a side laser irradiator for use in a new laser fusion proposed to enable efficient energy generation based on such performance.

To solve the problem, the side laser irradiator of the present invention, the side laser irradiation mechanism for irradiating a laser beam from the side of the target long shape with a reactant for fusion with used Laser Fusion In the side laser irradiator, the side laser irradiation mechanism includes a pulse width amplifying unit configured to expand a length in a width direction in a cross section of the supplied laser light, and the expanded laser light divided in the width direction, and a Suyo the configured divided and bent portions Once also the optical path difference between the laser beam between which is the divided by refracting each of the split laser beam, is a refractive had a reduction unit that will be configured to the respective laser beam to reduce the length of the width direction, the side laser irradiation mechanism, a plurality of said reduced laser beam It is arranged to illuminate from the side of the serial target.

In the side laser irradiator of the present invention, the side laser irradiation mechanism is a side laser extraction unit configured to extract a laser beam for each pulse from a pulse laser beam including a plurality of pulses having a time difference . It further has a side laser extraction portion configured to supply the extracted laser light to the side laser irradiation mechanism .

Side laser irradiator of the present invention is a laser extraction portion configured to take out a laser beam of the first pulse in a plurality of pulses of the pulsed laser beam, the laser beam taken out said, the target A laser extraction unit configured to irradiate a sub-target to generate ions to be sent to the reactant is further provided, and the laser beam extracted by the side laser extraction unit is included in a plurality of pulses of the pulse laser beam. The second and subsequent pulses of laser light .

In the side laser irradiator of the present invention, the side laser irradiation mechanism has a predetermined direction so that a thickness direction orthogonal to the width direction is orthogonal to a longitudinal direction of the object in the section of the reduced laser light. The rotating unit further rotates at an angle, and the laser beam rotated by the rotating unit is irradiated from the side of the object.

  In the side laser irradiator of the present invention, the predetermined angle is 90 degrees.

According to the present invention, the following effects can be obtained.
The side laser irradiator of the present invention is a side laser irradiator provided with a side laser irradiation mechanism that is used for laser fusion and irradiates a laser beam from the side of a long target having a reactant for nuclear fusion . The side laser irradiation mechanism divides the expanded laser beam in the width direction, a pulse width amplifier configured to expand the length in the width direction in the cross section of the supplied laser beam, and wherein the dividing and refractive part configured Suyo Once also the optical path difference between the laser beam between which is the divided by refracting each of the split laser beam, each of the refracted laser beam and a reduction unit that will be configured to reduce the length in the width direction, the side laser irradiation mechanism, or a plurality of the reduced laser beam laterally of said target It is arranged to illuminate.
Therefore, by expanding the length of the laser beam in the width direction, the laser beam is easily divided in the width direction, and further, an optical path difference is brought between the divided laser beams, so that the divided state Each of the laser beams can be irradiated from the side of the target with high resolution and high accuracy so as to have a time difference of femtoseconds to picoseconds.

In such a side laser irradiator, by injecting fusion fuel ions from one end in the longitudinal direction of the target, the ions are synchronized with the ions sent from one end of the target toward the other end of the target. Thus, when sequentially irradiating the plurality of reduced laser beams, further ions are added to the target reactant by the laser beam from the side of the target. As a result of the irradiation of the laser beam, ions move while electrons move. As a result, ions are accelerated by the formation of an electric field on the reactant of the target, and the fusion reaction proceeds from the reactant portion on one end side of the target to the reactant portion on the other end side. Will be amplified and continuously generated.
In such nuclear fusion, unlike conventional laser fusion, it is important to efficiently generate ions in the target and accelerate them in a uniform direction. In particular, when the target has a plurality of planar reactant parts, the direction of an electric field or the like that accelerates ions in the reactant part of the target tends to be perpendicular to the plane of the reactant part. Therefore, if the planes of a plurality of reactant parts are arranged perpendicular to the longitudinal direction of the target that coincides with the acceleration direction of the ions, ions accelerated by an electric field or the like in the reactant parts are caused to move to the other end of the target. It will be sent efficiently to the adjacent reactant parts on the side. Therefore, it avoids the problem of conventional laser fusion that efficiently and uniformly insulates and compresses the inside of the target, and efficiently generates ions in the target and accelerates them in a uniform direction. Can generate energy.
In the side laser irradiator of the present invention used for such laser fusion, the laser beam is easily divided in the width direction by enlarging the length of the laser beam in the width direction. Since an optical path difference is provided between the lights, each of the divided laser beams can be easily irradiated onto the target with a time difference. Therefore, it is possible to reliably irradiate laser light continuously from the side of the target so as to synchronize with the movement of ions from one end to the other end of the target, and efficiently generate a fusion reaction. Can do.

In the side laser irradiator of the present invention, the side laser irradiation mechanism is a side laser extraction unit configured to extract a laser beam for each pulse from a pulse laser beam including a plurality of pulses having a time difference . Since it further has a side laser extraction unit configured to supply the extracted laser light to the side laser irradiation mechanism, a time difference between pulses with respect to the movement of ions from one end of the target toward the other end In order to accurately synchronize using the laser beam, the laser beam can be further continuously irradiated from the side of the target, and a fusion reaction can be efficiently generated.

Side laser irradiator of the present invention is a laser extraction portion configured to take out a laser beam of the first pulse in a plurality of pulses of the pulsed laser beam, the laser beam taken out said, the target A laser extraction unit configured to irradiate a sub-target to generate ions to be sent to the reactant is further provided, and the laser beam extracted by the side laser extraction unit is included in a plurality of pulses of the pulse laser beam. Since the second and subsequent pulses of laser light , the ion implantation timing from one end to the other end of the target and the side of the target are more accurately synchronized with such ion movement. Can be continuously irradiated, and moreover, a nuclear fusion reaction can be efficiently generated.

In the side laser irradiator of the present invention, the side laser irradiation mechanism has a predetermined direction so that a thickness direction orthogonal to the width direction is orthogonal to a longitudinal direction of the object in the section of the reduced laser light. The rotating unit further rotates at an angle, and the laser beam rotated by the rotating unit is irradiated from the side of the object.
The predetermined angle is 90 degrees.
Therefore, each of the divided laser beams can be irradiated from the side of the object with higher resolution and higher accuracy. In particular, along the direction of ion movement from one end to the other end of the target, the divided laser light is accurately irradiated with a time difference, and the laser light from the side of the target is applied to the movement of ions. It is possible to synchronize more accurately and to generate a fusion reaction more efficiently. Further, with respect to the laser light before being rotated by the rotating unit, the width direction to be enlarged is orthogonal to the longitudinal direction of the target, and thus a plurality of mechanisms used for irradiation of the plurality of laser lights are brought close to each other. Can be arranged. Therefore, the side laser irradiator can be reduced in size, and further, a nuclear fusion reaction can be efficiently generated.

It is a schematic diagram of the laser fusion apparatus which has a side laser irradiator which concerns on embodiment of this invention. It is a block diagram of the structure regarding the laser irradiation of the laser fusion apparatus of FIG. It is a side view of the target used for the laser fusion apparatus of FIG. (A) In the laser fusion apparatus of FIG. 1, it is a figure which shows schematically the waveform of the pulsed laser beam sent from a laser oscillator. (B) It is a figure which shows roughly the waveform of the pulse laser beam obtained by taking out one pulse from the pulse laser beam of Fig.4 (a). It is a figure which shows roughly the waveform of the pulse voltage sent from a pulse voltage generator in the laser fusion apparatus which has a side laser irradiation device concerning the embodiment of the present invention. FIG. 3 is a block diagram illustrating a configuration of an adjustment area illustrated in FIG. 2. It is a schematic diagram which shows the structure of the mirror path | pass lamper of FIG. (A) It is a figure which shows roughly the cross section of the pulsed laser beam which intensity | strength was amplified by the amplifier of FIG. (B) It is a figure which shows roughly the cross section of the pulse laser beam which expanded the width of the cross section with the expander of FIG. (C) It is a figure which shows roughly the cross section of the pulse laser beam which reduced the width of the cross section with the reduction module of FIG. (D) It is a figure which shows roughly the cross section of the pulse laser beam which rotated the direction of the cross section with the rotation module of FIG.

A laser fusion apparatus having a side laser irradiator according to an embodiment of the present invention will be described.
Referring to FIG. 1, a laser fusion device 1 includes an elongated target 2. The laser fusion apparatus 1 has a sub-target 3, and this sub-target 3 sends an ion bunch B, which is a bundle of ions, to one end (hereinafter referred to as “incident end”) 2 a in the longitudinal direction of the target 2. It is configured to be able to. The ions of the ion bunch B (hereinafter referred to as “seed ions”) are generated by irradiating the sub target 3 with the pulsed laser light L emitted from the laser irradiator 4. The laser fusion apparatus 1 has a first side laser irradiator 5 and a second side laser irradiator 6, and the first side laser irradiator 5 and the second side laser irradiator 6 are Each is configured to be able to irradiate pulse laser beams M and N from the side of the target 2. The laser fusion apparatus 1 has a power generator 7, which uses energy supplied from the other end (hereinafter referred to as “exit end”) 2 b facing the incident end 2 a of the target 2 as electric power. It is configured to be convertible. The laser fusion device 1 has a voltage applicator 8, which is connected to the target 2. The laser fusion apparatus 1 includes a vacuum vessel 9 that can be evacuated. A target 2, a sub-target 3, and a generator 7 are arranged inside the vacuum vessel 9. The laser irradiator 4, the first side laser irradiator 5, the second side laser irradiator 6, and the voltage applicator 8 are connected to the controller 10. The controller 10 is configured to be able to control the laser irradiator 4, the first side laser irradiator 5, the second side laser irradiator 6, and the voltage applicator 8.

  Referring to FIG. 2, the laser fusion apparatus 1 includes a laser oscillator 11, and the laser oscillator 11 converts the pulse laser beam P into a first side laser irradiator 5 and a second side laser irradiator 6. It is comprised so that supply is possible. Further, the laser fusion device 1 has a pulse voltage generator 12. Although not particularly shown, the laser oscillator 11 and the pulse voltage generator 12 are also connected to the controller 10.

The target 2 will be described with reference to FIGS.
Referring to FIG. 2, the target 2 has a plurality of reaction parts 21, and these reaction parts 21 are made of a reactant that becomes a fusion fuel. When nuclear fusion is a DT reaction system, the reactant in the reaction unit 21 is deuterium, tritium, or a hydrocarbon molecule or polymer containing deuterium and / or tritium as a constituent element (for example, CxDy, CxTy). When the fusion is a pB reaction system, the reactant in the reaction unit 21 is preferably solid decaborane (B ₁₀ H ₁₄ ). Such a plurality of reaction parts 21 are arranged side by side in the longitudinal direction of the target 2. Referring to FIG. 3, in a region 2 d closer to the incident end 2 a than the intermediate portion 2 c in the longitudinal direction of the target 2 (hereinafter referred to as “incident side region”) 2 d, the cross section of each reaction unit 21 orthogonal to the longitudinal direction of the target 2. Are equal to each other. On the other hand, in the region 2e on the emission end 2b side (hereinafter referred to as “emission side region”) 2e from the intermediate portion 2c of the target 2, the area of the cross section of each reaction portion 21 orthogonal to the longitudinal direction of the target 2 is Increases from the intermediate portion 2c toward the exit end 2b. Further, although not particularly illustrated, each reaction unit 21 is configured to be separately applied with a voltage by the voltage applicator 8. By applying such a voltage, an electric field is generated in each reaction part 21, and a force from the outer periphery of the reaction part 21 toward the center acts on seed ions having a positive charge. It becomes. Further, as shown in FIG. 1, the incident side region 2 d of the target 2 has a pulse laser beam M from the first side laser irradiator 5 and a pulse laser beam N from the second side laser irradiator 6. Is irradiated.

The sub target 3 will be described with reference to FIGS. 1 and 2.
The sub-target 3 disposed on the incident end 2 a side of the target 2 is made of the same type of reactant as that of the target 2. The sub-target 3 is formed in a substantially hemispherical thin film shape, and is curved so as to protrude in a direction from the emission end 2b of the target 2 toward the incidence end 2a. Although not particularly shown, the sub-target 3 is disposed on a central axis 2 f that extends in the longitudinal direction from the incident end 2 a of the target 2 toward the emission end 2 b through the center of the cross section of the target 2.

The laser irradiator 4, the first side laser irradiator 5, the second side laser irradiator 6, the laser oscillator 11, and the pulse voltage generator 12 are described with reference to FIGS. 1, 2, and 4 to 6. I will explain.
Referring to FIG. 2, the laser irradiator 4 has a Pockels cell 41, and the Pockels cell 41 is a laser that extracts a pulsed laser beam L <b> 1 including one pulse from a pulsed laser beam P supplied by the laser oscillator 11. It is comprised as an extraction part. Referring to FIG. 4A, the pulsed laser light P supplied from the laser oscillator 11 includes a plurality of pulses excited at a period T1 (frequency f1). As an example, the pulse laser beam P is preferably a picosecond laser beam or a femtosecond laser beam having an output level of TW (terawatts). Referring again to FIG. 2, the laser irradiator 4 has a pulse stretcher 42, and the pulse stretcher 42 is configured as a pulse width amplification unit that amplifies the pulse width of the pulse laser light L <b> 1 extracted by the Pockels cell 41. ing. The laser irradiator 4 includes an amplifier 43. The amplifier 43 is configured as a laser amplification unit that amplifies the intensity of the pulsed laser light L2 whose pulse width is amplified by the pulse stretcher 42. The laser irradiator 4 has a pulse compressor 44, and the pulse compressor 44 is configured as a pulse width compression unit that compresses the pulse width of the pulse laser light L3 whose intensity is amplified by the amplifier 43. The laser irradiator 4 has a condensing mirror 45, and the condensing mirror 45 is configured as a condensing unit that condenses the pulsed laser light L 4 whose pulse width is reduced by the pulse compressor 44. The pulse laser beam L condensed by such a condensing mirror 45 is irradiated to the sub-target 3.

  Referring to FIG. 2, the first side laser irradiator 5 has a plurality of side laser irradiation mechanisms 50. The side laser irradiation mechanisms 50 are arranged side by side in the longitudinal direction of the target 2 so that the plurality of reaction portions 21 of the target 2 can be irradiated with pulsed laser light. In the embodiment of the present invention, 25 side laser irradiation mechanisms 50 are provided. In particular, in FIG. 2, the first of the 25 side laser irradiation mechanisms 50 from the emission end 2a of the target 2, Three side laser irradiation mechanisms 50 arranged in the second and 25th positions are shown. Note that the second side laser irradiator 6 is configured in the same manner as the first side laser irradiator 5, and thus the description of the second side laser irradiator 6 is omitted.

  Referring to FIG. 2, the side laser irradiation mechanism 50 has a Pockels cell 51. The Pockels cell 51 includes a pulse laser beam M1 (one pulse) from a pulse laser beam P supplied by the laser oscillator 11. This is configured as a side laser extraction unit for extracting (see FIG. 4B). The Pockels cell 51 is provided with a voltage amplifier 51a. Each voltage amplifier 51 a is connected to the pulse voltage generator 12. The pulse voltage generator 12 is configured to generate a voltage based on a rectangular pulse wave (see FIG. 5) including a plurality of rectangular pulses excited at a period T2 (frequency f2). The side laser irradiation mechanism 50 has an adjustment region 50a, and this adjustment region 50a is configured to adjust the pulse laser light M1 extracted by the Pockels cell 51 so as to irradiate the target 2.

  Details of the adjustment region 50a will be described with reference to FIGS. 6, 7, and 8A to 8D. Referring to FIG. 6, the adjustment region 50 a includes a pulse stretcher 52, and this pulse stretcher 52 is configured as a pulse width amplification unit that amplifies the pulse width of the pulse laser light M <b> 1 extracted by the Pockels cell 51. Yes. The adjustment region 50 a includes an amplifier 53, and the amplifier 53 is configured as a laser amplification unit that amplifies the intensity of the pulsed laser light M <b> 2 whose pulse width is amplified by the pulse stretcher 52. The adjustment region 50a has an expander 54. The expander 54 has a width w1 (FIG. 8) in one direction (hereinafter referred to as “width direction”) of the pulse laser beam M3 whose intensity is amplified by the amplifier 53. (See (a)). The adjustment area 50 a has a mirror path lamper 55. Referring to FIG. 7, the mirror path lamper 55 divides the pulse laser beam M4 whose width is increased by the expander 54 into i (i = 2, 3,...) In the width direction, and the divided pulse laser. It is configured as a splitting and refracting portion that causes an optical path difference D (= 1 / 2D × 2) by refracting between the lights.

  Referring again to FIG. 6, the adjustment region 50 a includes a reduction module 56, which includes a plurality of pulsed laser beams m <b> 5 (hereinafter referred to as “divided laser beams”) that are split and refracted by the mirror path lamper 55. Is configured as a reduction unit that reduces the width w2 (see FIG. 8B). The adjustment region 50a includes a rotation module 57. The rotation module 57 has a thickness of a cross section perpendicular to the width direction of the pulse laser beam M6 having a plurality of divided laser beams m6 reduced by the reduction module 56. It is configured as a rotating unit that rotates the direction at an angle z <b> 1 with respect to the longitudinal direction of the target 2. As an example, the angle z1 may be set so that the thickness direction of the pulsed laser light M6 is orthogonal to the target 2. Specifically, the angle z1 is preferably 90 degrees. The adjustment region 50a includes a pulse compressor 58. The pulse compressor 58 serves as a pulse width compression unit that reduces the pulse width of the pulse laser beam M7 having a plurality of divided laser beams m7 rotated by the rotation module 57. It is configured. The adjustment region 50a has a condensing mirror 59. The condensing mirror 59 serves as a condensing unit that condenses the pulse laser beam M8 having a plurality of divided laser beams m8 amplified by the pulse compressor 58. It is configured. The target 2 is irradiated with the pulsed laser light M condensed by such a condensing mirror 59.

Here, a detailed configuration of the mirror path lamper 55 will be described with reference to FIG.
The mirror path lamper 55 has a plurality of mirrors. In FIG. 7, as an example, a case where the mirror path lamper 55 includes four mirrors 55a, 55b, 55c, and 55d will be described. The four mirrors 55a to 55d are arranged at equal intervals, and the reflecting surfaces of the mirrors 55a to 55d face the same direction and are parallel to each other. The reflecting surfaces of the mirrors 55a to 55d are arranged so as to have an angle z2 with respect to the incident pulse laser beam M4. The pulse laser beam M4 incident on the mirror path lamper 55 is split into four split laser beams m5 by the mirrors 55a to 55d and refracted at an angle of 2 × z2.

The power generator 7 will be described with reference to FIG.
The power generator 7 disposed on the emission end 2 a side of the target 2 is disposed on the central axis 2 f of the target 2. The power generator 7 is configured to convert the energy of the ion bunch B supplied from the emission end 2b of the target 2 into electric power.

The voltage applicator 8 will be described with reference to FIG.
The voltage applicator 8 is connected to the target 2 and can apply a voltage to each reaction part 21 of the target 2 separately. Therefore, an electric field is generated in each reaction part 21 separately.

The controller 10 will be described with reference to FIG.
The controller 10 irradiates the pulsed laser light L by the laser irradiator 4, irradiates the pulsed laser light M including the divided laser light m by the first side laser irradiator 5, and uses the second side laser irradiator 6. Control that synchronizes irradiation of the pulse laser beam N and voltage application to the reaction part 21 of the target 2 by the voltage applicator 8 is possible.

The operation of laser fusion in the laser fusion apparatus 1 of the embodiment of the present invention will be described with reference to FIG. Detailed operations of the laser irradiator 4, the first side laser irradiator 5, the second side laser irradiator 6, the laser oscillator 11, and the pulse voltage generator 12 will be described later.
Under the control of the controller 10, the sub target 3 is irradiated with the pulsed laser light L from the laser irradiator 4, and seed ions are generated by the sub target 3. An ion bunch B, which is a bundle of generated seed ions, is sent to the incident end 2 a of the target 2. The ion bunches B sent to the incident end 2a are sequentially sent to the reaction units 21 from the incident end 2a of the target 2 toward the exit end 2b. Before the ion bunches B of the seed ions reach the reaction unit 21, the reaction unit 21 is irradiated with the pulse laser light M from the first side laser irradiator 5 under the control of the controller 10. At the same time that B reaches the reaction part 21, the control part 10 controls the reaction part 21 to be irradiated with the pulsed laser light N from the second side laser irradiator 6, and the reaction part 21 is irradiated with the voltage applicator 8. Apply voltage by The pulse laser beam M from the first side laser irradiator 5 and the pulse laser beam N from the second side laser irradiator 6 are sequentially transferred from the incident end 2a to the emission end 2b of the target 2, respectively. The reaction unit 21 is irradiated. Further, a voltage is applied to the reaction unit 21 sequentially by the voltage applicator 8 from the incident end 2a of the target 2 toward the exit end 2b. Thereafter, the energy of the ion bunch B that passes through the target 2 and is sent from the emission end 2 b of the target 2 is converted into electric power by the power generator 7.

Here, the detailed operation of the laser oscillator 11 will be described with reference to FIG. Note that. Since the detailed operation of the second side laser irradiator 6 is the same as that of the first side laser irradiator 5, it will be omitted.
The laser oscillator 11 controlled by the controller 10 oscillates a pulsed laser beam P (see FIG. 4A) including a plurality of pulses excited at a period t1 (frequency f1). Supply to the laser irradiator 4. Thereafter, the pulse laser beam P is supplied to the first side laser irradiator 5. In the first side laser irradiator 5, the pulsed laser light P is sequentially supplied from the side laser irradiation mechanism 50 at the incident end 2a of the target 2 toward the side laser irradiation mechanism 50 at the emission end 2b. Although not particularly shown, the second side laser irradiator 6 also sequentially supplies the pulsed laser light P from the side laser irradiation mechanism at the incident end 2a of the target 2 toward the side laser irradiation mechanism at the emission end 2b.

The detailed operation of the laser irradiator 4 will be described with reference to FIG.
The Pockels cell 41 of the laser irradiator 4 takes out the pulsed laser light L1 corresponding to the first pulse among the plurality of pulses of the supplied pulsed laser light P. The pulse stretcher 42 amplifies the pulse width of the extracted pulsed laser light L1. The amplifier 43 amplifies the intensity of the pulsed laser light L2 whose pulse width is amplified. The pulse compressor 44 compresses the pulse width of the pulsed laser light L3 whose intensity has been amplified. The condensing mirror 45 condenses the pulsed laser light L4 whose pulse width is compressed, and the condensed pulsed laser light L5 is irradiated onto the sub-target 3.

The detailed operation of the first side laser irradiator 5 will be described with reference to FIGS. 2, 6, and 7. FIG.
Referring to FIG. 2, in the side laser irradiation mechanism 50 arranged closest to the incident end 2 a of the target 2 in the first side laser irradiator 5, the Pockels cell 51 has a plurality of pulses of the supplied pulsed laser light P. The pulse laser beam M1 corresponding to the second pulse is extracted. Subsequently, in the side laser irradiation mechanism 50 arranged second with respect to the incident end 2a of the target 2, the Pockels cell 51 corresponds to the third pulse among the plurality of pulses of the supplied pulsed laser light P. The pulse laser beam M1 to be extracted is taken out. Further, in the side laser irradiation mechanism 50 arranged at the third to 25th positions with respect to the incident end 2a of the target, the Pockels cell 51 is the fourth to the 26th of the plurality of pulses of the supplied pulsed laser light P, respectively. The pulses are sequentially extracted.

  Here, when the pulse laser beam M1 is sequentially extracted by each Pockels cell 51, the pulse voltage generator 12 controlled by the controller 10 includes a plurality of rectangular pulses excited at a period t2 (frequency f2). A rectangular pulse wave (see FIG. 5) is applied to the voltage amplifier 51 a of each Pockels cell 51. The voltage amplifier 51a of each Pockels cell 51 amplifies the rectangular pulse voltage of the rectangular pulse wave that coincides with the timing at which the pulse laser beam M1 of each Pockels cell 51 is extracted. Thus, in the first to 25th side laser irradiation mechanisms 50 based on the incident end 2a of the target 2, the second to 26th pulses among the plurality of pulses of the pulsed laser light P supplied by the Pockels cell 51 are used. Are sequentially taken out.

  Further, the operation of the adjustment region 50a of the side laser irradiation mechanism 50 will be described using the first side laser irradiation mechanism 50 with reference to the incident end 2a of the target 2 with reference to FIGS. The second to 25th side laser irradiation mechanisms 50 based on the incident end 2a of the target 2 have the same configuration as that of the first side laser irradiation mechanism 50, and thus the description thereof is omitted.

  Referring to FIG. 6, the pulse stretcher 52 amplifies the pulse width of the extracted pulsed laser beam M1. The amplifier 53 amplifies the intensity of the pulsed laser light M2 whose pulse width is amplified. The cross section of the pulse laser beam M3 whose intensity has been amplified in this way has a width w1 and a thickness t (see FIG. 8A). The expander 54 expands the width w1 of the cross section of the pulse laser beam M3. The pulse laser beam M4 whose cross-sectional width is enlarged has a width w2 and a thickness t (see FIG. 8B). The mirror path lamper 55 divides the pulse laser beam M4 and causes an optical path difference D to each of the divided divided laser beams m5 (see FIG. 7). The reduction module 56 reduces the width w2 of the cross section of the pulse laser beam M5 including the divided laser beam m5. The cross section of the reduced pulse laser beam M6 has a width w3 and a thickness t (see FIG. 8C). As an example, the width w3 is larger than the thickness t, but the width w3 may be smaller than the thickness t. The rotation module 57 rotates at an angle z1 so that the thickness direction of the pulse laser beam M6 is orthogonal to the longitudinal direction of the target 2 (see FIG. 8D). The pulse compressor 58 compresses the pulse width of the pulse laser beam M7 including the plurality of rotated divided laser beams m7. The condensing mirror 59 condenses the compressed pulse laser light M8 of the plurality of divided laser lights m8. A pulsed laser beam M including a plurality of condensed laser beams m is irradiated onto the reaction portion 21 arranged closest to the incident end 2 a of the target 2. Each of the plurality of divided laser beams m is sequentially irradiated onto the reaction unit 21 with a time difference.

The action of fusion generated in the target 2 by such an operation will be described with reference to FIG.
Before the seed ions in the ion bunch B sent from the sub-target 3 reach the reaction part 21 closest to the emission end 2 a of the target 2, a pulse from the first side laser irradiator 5 is applied to the reaction part 21. As a result, the laser beam M is irradiated, plasma is generated, and the temperature of ions (hereinafter referred to as “reactant ions”) and electrons in the reaction portion 21 rises. Increasing the temperature of the reactant ions will decrease the nuclear stopping power of the reactants, and increasing the temperature of the electrons will decrease the electronic stopping power of the reactants. Therefore, when the seed ions pass through the target 2, the energy of the seed ions is prevented from being taken away by the reactant ions and electrons. Further, by irradiating the reaction part 21 with the pulse laser beam M from the first side laser irradiator 5 as described above, the “Coulomb explosion phenomenon of cluster particles” and “ Reactant ions are accelerated like phenomena such as “high field sheath acceleration”.

  At the same time as the seed ions reach the reaction part 21 closest to the emission end 2 a of the target 2, plasma is generated by irradiating the reaction part 21 with the pulsed laser light N from the second side laser irradiator 6. Laser light pressure is generated that accelerates ions from the incident end 2a of the target 2 toward the exit end 2b. At this time, the reactant ions accelerated by the irradiation of the pulsed laser light M from the first side laser irradiator 5 and the irradiation of the pulsed laser light N from the second side laser irradiator 6, and the seed ions In between, "Coulomb elastic scattering" occurs. Here, since the reaction part 21 and the sub-target 3 are the same substance, the seed ions and the reactant ions become ions of the same substance. Therefore, the kinetic energy of the seed ions is changed by the “Coulomb elastic scattering”. The kinetic energy is increased with the fusion reaction within the region 21, and this kinetic energy is transferred to the reactant ions. Further, the accelerated reactant ions are taken into the ion bunches B of the seed ions, and the kinetic energy of the ion bunches B increases. That is, the kinetic energy generated by the nuclear fusion reaction is given to ions that contribute to the next nuclear fusion reaction by “Coulomb elastic scattering”.

  At the same time as the seed ions reach the reaction part 21 closest to the emission end 2 a of the target 2, a voltage is applied to the reaction part 21 by the voltage applicator 8. By applying this voltage, an electric field is generated in the reaction part 21, and a force from the outer periphery of the reaction part 21 toward the center acts on the seed ions having a positive charge. Therefore, the movement direction of the seed ions moving along the central axis 2f of the target 2 is suppressed from being dissipated out of the target 2 due to “Coulomb elastic scattering” or the like.

  Such an action is sequentially repeated in each reaction part 21 of the incident side region 2d of the target 2 from the incident end 2a of the target 2 toward the intermediate part 2c, and the fusion reaction of the seed ions is performed on the incident end of the target 2. It will generate | occur | produce continuously toward the intermediate part 2c from 2a.

  Further, in the reaction part 21 of the emission side region 2e of the target 2, since the pulse laser beam is not irradiated from the outer periphery of the target 2, the reactant ions and electrons in the reaction part 21 are in a cooled state. However, due to the nuclear and electronic stopping power of the reactants, the kinetic energy of the ion bunches B of the seed ions is immediately transferred to the reactant ions, resulting in an increase in the temperature of the target electron ions and electrons. It becomes. In this way, the increase in energy due to the fusion reaction exceeds the loss lost by heating the target electron ions and electrons is called “ignition of the fusion reaction” and the point where the ignition of the fusion reaction takes place. It is called “the ignition point of the fusion reaction”.

  Further, in view of these operations and actions, the pulse laser beam M from the first side laser irradiator 5 and the pulse laser beam N from the second side laser irradiator 6 are irradiated to the reaction unit 21. In a moment, a non-equilibrium and ultra-high temperature plasma is generated, and the ion bunch B moves within the target 2 while generating “Coulomb elastic scattering” and “nuclear fusion reaction” within a short period of picoseconds. . Therefore, in the fusion reaction using the target in the embodiment of the present invention, unlike the conventional laser fusion, the influence of the “Rayleigh-Taylor instability” regarding the plasma is not a problem, and the inside of the target is efficiently and The problem of uniformly insulating and compressing is avoided.

As described above, according to the embodiment of the present invention, further ions are added to the reaction part 21 of the target 2 by the pulse laser beams M and N irradiated from the side of the target 2. As a result of the irradiation of the pulse laser beams M and N, the electrons move while ions are left. As a result, ions are accelerated by forming an electric field in the reaction part 21 of the target 2, and the fusion reaction is performed from the reaction part 21 on the emission end 2 a side of the target 2 to the reaction part on the emission end side. As the signal is amplified toward 21, it is continuously generated.
In such nuclear fusion, unlike conventional laser fusion, it is important to efficiently generate ions in the target and accelerate them in a uniform direction. In particular, when the target 2 has a plurality of planar reaction parts 21, the direction of an electric field or the like that accelerates ions in the reaction part 21 of the target 2 tends to be perpendicular to the plane of the reaction part 21. Therefore, if the planes of the plurality of reaction portions 21 are arranged perpendicular to the longitudinal direction of the target 2 that coincides with the acceleration direction of ions, ions accelerated by an electric field or the like in the reaction portion 21 are emitted from the target 2. It will be efficiently sent to the reaction part 21 adjacent on the end 2b side. Therefore, by avoiding the problem of conventional laser fusion that efficiently and uniformly insulates and compresses the inside of the target 2, ions are efficiently generated in the target 2 and accelerated in a uniform direction. Energy can be generated.
In the first side laser irradiator 5 and the second side laser irradiator 6 used for such nuclear fusion, the width of the cross section of the pulse laser beam M3 is increased, so that the expanded pulse laser beam M4 has a width. Since the laser beam m5 is easily divided in the direction and an optical path difference D is provided between the divided laser beams m5, the target 2 can be easily irradiated with each of the divided laser beams m with a time difference. Therefore, the pulse laser beams M and N can be continuously irradiated from the side of the target 2 so as to synchronize with the movement of seed ions from one end of the target toward the other end, and efficiently generate a fusion reaction. Can be made.

  According to the embodiment of the present invention, the pulse laser beam P supplied to the first side laser irradiator 5 and the second side laser irradiator 6 is generated from the pulse laser beam including a plurality of pulses having a time difference. Since the configuration is obtained by taking out each pulse, the target 2 has a structure that accurately synchronizes the movement of ions from the incident end 2a to the exit end 2b of the target 2 using the time difference of the pulse. Pulse laser beams M and N can be further continuously irradiated from the side, and a nuclear fusion reaction can be efficiently generated.

  According to the embodiment of the present invention, the pulse laser beam L1 supplied to the laser irradiator 4 to generate ions to be injected into the target 2 is included in a plurality of pulses of the pulse laser P sent from the laser oscillator 11. A pulse laser beam obtained by taking out the first pulse and supplied to the first side laser irradiator 5 and the second side laser irradiator 6 is a plurality of pulse lasers P sent from the laser oscillator 11. Since the configuration is obtained by extracting the second and subsequent pulses in the pulse, it is more accurately synchronized with the ion implantation timing from the incident end 2a to the exit end 2b of the target 2 and the movement of such ions. As described above, the pulse laser beams M and N can be continuously irradiated from the side of the target 2, and the fusion reaction can be performed more efficiently. Produced cell can be.

  According to the embodiment of the present invention, the first side laser irradiator 5 and the second side laser irradiator 6 change the thickness direction of the pulse laser beams M and N irradiated to the target 2 in the longitudinal direction of the target 2. It is rotated at a predetermined angle z1 so as to be orthogonal to the direction. Therefore, the divided laser beam m is reliably irradiated with a time difference along the moving direction of the seed ions from the incident end 2a to the exit end 2b of the target 2, and the pulse laser beam M from the side of the target 2 is ionized. It is possible to synchronize more accurately with respect to the movement of nuclei, and to generate a fusion reaction more efficiently. Further, with respect to the pulsed laser light before being rotated by the rotation module 57, the width direction to be enlarged is orthogonal to the longitudinal direction of the target 2, so that the side laser mechanisms can be arranged close to each other. Therefore, the first side laser irradiator 5 and the second side laser irradiator 6 can be miniaturized, the laser fusion apparatus 1 can be miniaturized, and a nuclear fusion reaction can be efficiently generated.

  Although the embodiments of the present invention have been described so far, the present invention is not limited to the above-described embodiments, and various modifications and changes can be made based on the technical idea of the present invention.

  For example, as a modification of the present invention, the first side laser irradiator 5 and / or the second side laser irradiator 6 may be used in addition to the laser fusion device, and the object is elongated by the laser light. The present invention may be used for laser processing for processing an object, laser measurement for measuring a long object by laser light, and the like. Each of the divided laser beams can be irradiated from the side of the object with high resolution and high accuracy so as to have a time difference of femtoseconds to picoseconds.

[Example]
An example using the first side laser irradiator 5 and the second side laser irradiator 6 according to the embodiment of the present invention will be described.
In the examples, the fusion reaction is a DT reaction system. In the case of the DT reaction system, the energy of deuterium nuclear ions required for inducing fusion is as high as about 50 to several hundred keV, and in the example, the kinetic energy K is 100 keV. In this case, when the traveling speed V of the seed ions in the target 2 is calculated, the result shown in (Expression 1) is obtained. In (Expression 1), m is the mass of ions and c ₀ is the speed of light.

According to the calculation of (Expression 1), the traveling speed V of the seed ions in the target 2 is 3.096 × 10 ⁶ m / s, and this value is about 1/100 of the light velocity c _0. Equivalent to. That is, the first side laser irradiator 5 and the second side laser irradiator 6 emit the pulse laser beams M and N from the side of the target 2 in synchronization with the seed ions moving at such a traveling speed V. It is necessary to irradiate continuously.

In the embodiment, the pulse widths of the pulse laser beams M and N irradiated by the first side laser irradiator 5 and the second side laser irradiator 6 are 200 fs (femtoseconds). The energy per pulse of N is 10J. When the optical peak power P _p of such pulse laser beams M and N is calculated, the result shown in (Expression 2) is obtained.

According to the calculation of (Expression 2), the optical peak power P _p is 50 TW (terawatts). By condensing such pulsed laser light corresponding to a narrow region of the target 2, ions and electrons that move at high speed can be generated in the reaction portion 21 of the target 2. The cross-sectional area of the focused pulsed laser beam is a unit of about μm ^{2 to} mm ² , and the power of the pulsed laser beam is estimated to exceed a threshold value P ₀ as shown in (Equation 3). .

  In the embodiment of the present invention, the pulse laser beam irradiated to the target 2 is divided into a plurality of divided laser beams, and the optical path difference D of the divided laser beams divided at both ends in the width direction is (Equation 4) The result is as shown in.

  In the embodiment, the pulsed laser light irradiated to the target 2 is divided into 1000 and is composed of 1000 divided laser lights. Therefore, the energy per pulse of the divided laser light in the 1000 divided pulse laser lights M and N is 1000 times the energy per pulse of the non-divided pulse laser light, which is about 10 kJ. It has become.

In addition, ions and electrons that move at high speed after being irradiated with a pulse laser are considered to maintain a high energy state for several ps (picoseconds). Therefore, the time for maintaining the high energy state of ions and electrons moving at high speed is set to 4 ps, and the following (Expression 5) and (Expression 6) are calculated. When a pulse laser beam having a pulse width of 200 fs (femtosecond) is irradiated in a “non-divided state”, the distance X _{step in} which deuterium nuclear ions having a kinetic energy K of 100 keV travel between 4 ps is expressed by The result is as shown in 5). In (Expression 5), the traveling speed V of the seed ions obtained by (Expression 1) V = 3.096 × 10 ⁶ (m / s) is used.

On the other hand, when the pulse laser beams M and N having a pulse width of 200 fs are irradiated “in a 1000 divided state”, the distance X _{unit in} which deuterium nuclear ions having a kinetic energy K of 100 keV travel between 4 ps is , (Equation 6) results. In (Expression 6), similarly to (Expression 5), the traveling speed V of the seed ions obtained by (Expression 1) V = 3.096 × 10 ⁶ (m / s) is used.

According to the calculation of (Formula 6), X _unit is about 12.4 mm. Therefore, the length in the longitudinal direction of the target 2 irradiated with the pulse laser beams M and N is preferably about 12.4 mm, and the width of the pulse laser beams M and N is preferably 12.4 mm. In the embodiment, the width w2 of the pulse laser beams M and N is enlarged 100 times the X _unit , and the width w2 of the pulse laser beams M and N is as shown in (Expression 7).

  If the width w2 of the pulse laser beams M and N is such a large value, the pulse laser beams M and N can be easily divided into 1000. Further, according to (Equation 1), based on the traveling speed V of the seed ions being 1/100 of the speed of light, the optical path difference D of the divided laser beams at both ends in the width direction in the pulse laser beams M and N Gives a result as shown in (Equation 8). The pulse laser beams M and N are divided into 1000 in the width direction, and the widths of the divided laser beams of the pulse laser beams M and N are very small. The distance w2 ′ between the divided laser beams approximates the width w2 of the pulse laser beams M and N, respectively (see FIG. 7). Therefore, (Equation 8) is calculated on the assumption that the distance w2 'between the centers of the divided laser beams at both ends in the width direction in the pulse laser beams M and N corresponds to the width w2 of the pulse laser beams M and N, respectively.

  Based on (Expression 4), (Expression 7), and (Expression 8), when the angle z2 of the reflecting surface of the mirror with respect to the incident pulse laser beam M4 is calculated, the angle z2 is 26.6 degrees. Therefore, in the embodiment, the mirror path lamper 55 set at such an angle z2 = 26.6 degrees allows the pulsed laser beams M and N to be emitted from the incident end 2a of the target 2 at the same speed as the deuterium ions of 100 kV. The target 2 can be irradiated so as to go to the emission end 2b.

DESCRIPTION OF SYMBOLS 1 Laser fusion apparatus 2 Target 2a Incidence end 2b Output end 3 Subtarget 4 Laser irradiator 5 First side laser irradiator 6 Second side laser irradiator 11 Laser oscillator 11
21 reaction section 51 Pockels cell 54 expander 55 mirror path lamper 56 reduction module 57 rotation module B ion bunch L, L1, L2, L3, L4 pulse laser beam M, M1, M2, M3, M4, M5, M6, M7, M8 pulse laser beam m, m5, m6, m7, m8 Split pulse laser beam (split laser beam)
N pulse laser beam P pulse laser beam w1, w2, w2 ', w3 width t thickness

Claims (5)

In a side laser irradiator equipped with a side laser irradiation mechanism that irradiates a laser beam from the side of an elongated target that is used for laser fusion and has a reactant for fusion ,
The side laser irradiation mechanism is
A pulse width amplifying unit configured to expand the length in the width direction in the cross section of the supplied laser beam ;
Dividing the expanded laser beam in the width direction and divides configured Once also the optical path difference Suyo between the laser beam between which is the divided by refracting each of the split laser beam And a refraction part,
Reduction unit and which each of the refracted laser beam Ru is configured to reduce the length in the width direction
Have
A side laser irradiator, wherein the side laser irradiation mechanism is arranged to irradiate a plurality of the reduced laser beams from the side of the target . The side laser irradiation mechanism is a side laser extraction unit configured to extract a laser beam for each pulse from a pulsed laser beam including a plurality of pulses having a time difference from each other. The side laser irradiator according to claim 1, further comprising a side laser extraction unit configured to be supplied to the laser irradiation mechanism. A laser extraction unit configured to extract a laser beam of a first pulse among a plurality of pulses of the pulsed laser beam, and generates ions to be sent to the reactant of the target by using the extracted laser beam. A laser take-out unit configured to irradiate the sub-target for
3. The side laser irradiator according to claim 2, wherein the laser beam extracted by the side laser extraction unit is a laser beam of the second and subsequent pulses among the plurality of pulses of the pulse laser beam. The side laser irradiation mechanism further includes a rotating unit that rotates at a predetermined angle so that a thickness direction orthogonal to the width direction is orthogonal to a longitudinal direction of the target in a cross section of the reduced laser light. ,
The side laser irradiator according to any one of claims 1 to 3, wherein the laser beam rotated by the rotating unit is configured to be irradiated from a side of the target. The side laser irradiator according to claim 4, wherein the predetermined angle is 90 degrees.

Images