Classifications

• • G—PHYSICS
  • G21—NUCLEAR PHYSICS; NUCLEAR ENGINEERING
  • G21B—FUSION REACTORS
  • G21B1/00—Thermonuclear fusion reactors
  • G21B1/11—Details
  • G21B1/23—Optical systems, e.g. for irradiating targets, for heating plasma or for plasma diagnostics
• • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
  • Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
  • Y02E30/00—Energy generation of nuclear origin
  • Y02E30/10—Nuclear fusion reactors

Definitions

• the present invention relates to an accumulator of light energy, particularly an accumulator of light energy from a light beam, e.g. a laser beam or a non-coherent light beam.
• Concentrators of light energy, which use a plurality of laser beams which are made to converge towards a single point, so as to concentrate their energy in that point.
• the most powerful laser concentrator is the National Ignition Facility (NIF), a laser- based inertial confinement fusion research installation at the Lawrence Livermore National Laboratory in Livermore, United States.
• NIF National Ignition Facility
• the NIF uses a plurality of laser generators (in particular number 192) that generate a respective plurality of laser beams which, made to converge at a convergence point, heat the target, e.g., small amounts of hydrogen isotopes, until a nuclear fusion reaction starts.
• This structure has the main drawback linked to the need of using multiple laser generators and of related energy consumption for the power supply of each single laser generator.
• each mode will oscillate independently, like a group of independent lasers and emits slightly different frequencies in a random fashion due to small thermal and electrical variations of the laser materials.
• irregular interferences are produced with beats that generate fluctuations in intensity of the laser pulses.
• lasers with many thousands of modes these interference effects lead to a nearly constant output intensity: the laser is then said to operate with cw wave or continuously.
• each resonant cavity is delimited longitudinally by a saturable absorber mirror and by an output coupler mirror, with interposition of a gain medium (gain).
• the intense light pulses are temporally separated from each other by a time ⁇ given by:
• each light pulse When the pulse reflects on the output coupler mirror, this emits a light pulse outside the laser yielding most of its energy; in turn, the return pulse, after being reflected on the saturable absorber mirror regains the energy transferred through the gain medium.
• the duration of each light pulse is determined by the number of modes that oscillate in phase induced by a locking system. If N is the number of modes locked with ⁇ frequency separation, the bandwidth in locked mode is in general ⁇ * ⁇ . In practice, however, the minimum possible pulse duration is given by:
• mode-locked lasers which are pumped by laser diodes, therefore able to generate output powers of tens of Watts and subpicosecond pulses and also generate trains of pulses with repetition rates of several GHz.
• W a the supply power of the laser accumulator which, besides the laser generator, comprises its pumping apparatuses to obtain high laser output powers and also the power of all the reflective apparatuses which partially offset the loss of light reflection (excluding the electro-polarizer powers). If we then indicate by 3 ⁇ 4 the injection ratio of the actual light power Wi injected by the laser generator, we have that
• the NIF laser produces a power density equal to 10 15 W/cm 2 .
• each of the 192 lasers is 9375 J.
• the main aim of the present invention is to provide an accumulator of light energy which allows to obtain operating performance, in terms of generated power density, comparable to those of the devices of known type by reducing the number of light energy sources and/or the related operating power, with a consequent reduction in energy consumption.
• One object of the present invention is to provide an accumulator of light energy which has reduced overall dimensions and structural complexity compared to the devices of known type.
• Another object of the present invention is to provide an accumulator of light energy which allows to overcome the mentioned drawbacks of the prior art within the ambit of a simple, rational, easy and effective to use as well as affordable solution.
• Figure 1 is a top view of an accumulator of light energy according to the invention in a first embodiment
• Figure 2 is a sectional view according to the section II- II track of Figure 1, wherein the accumulator according to the invention has a first variation of deflector elements;
• Figure 3 is an enlargement of a detail of Figure 2;
• Figure 4 is a sectional view according to the section II-II track of Figure 1, wherein the accumulator according to the invention has a second variation of deflector elements;
• Figure 5 is a view from V of Figure 4;
• Figure 6 is a schematic view of the accumulator according to the invention in a second embodiment, dodecahedral in the example;
• Figures 7-12 are schematic views of the light beams reflected by the reflective elements within the accumulation chamber of the accumulator of Figure 6;
• Figures 13-18 are schematic views representative of the geometry of paths of reflections of a laser beam
• Figure 19 schematically shows an isosceles optical prism with total double reflection
• Figure 20 shows the diagram of an optical prism usable as an input of the system.
• an accumulator of light energy in particular of energy from a laser beam, i.e., a light beam of coherent light, monochromatic and concentrated in a highly collimated rectilinear beam has been globally indicated by 10.
• the accumulator 10 comprises at least one source of a light beam, e.g. a laser generator 20, which is adapted to emit a laser beam, e.g. of the continuous type or with discreet pulses.
• a source of a light beam e.g. a laser generator 20
• a laser beam e.g. of the continuous type or with discreet pulses.
• the laser generator 20 e.g., has a supply power W a substantially between 10 5 W and 10 10 W.
• the accumulator 10 also comprises an accumulation chamber 30 with an entrance 31, e.g., comprising a total-reflection prism transparent to light beams in a cross direction (e.g., from the outside towards the inside of the accumulation chamber 30) and reflecting the light beams in the opposite cross direction (e.g., from the inside towards the outside of the accumulation chamber 30), through which the laser beam emitted by the laser generator 20 enters the accumulation chamber 30.
• an entrance 31 e.g., comprising a total-reflection prism transparent to light beams in a cross direction (e.g., from the outside towards the inside of the accumulation chamber 30) and reflecting the light beams in the opposite cross direction (e.g., from the inside towards the outside of the accumulation chamber 30), through which the laser beam emitted by the laser generator 20 enters the accumulation chamber 30.
• the accumulator 10 comprises means for forming the vacuum, e.g. a vacuum pump 32 adapted to define a high vacuum inside the accumulation chamber 30.
• a plurality of reflective elements 40 which are oriented to reflect the laser beam that enters the accumulation chamber 30 along at least a closed reflection path, e.g. along a closed broken line contained inside the accumulation chamber 30.
• each reflective element 40 comprises a saturable absorber mirror 41.
• each reflective element 40 comprises at least one gain medium 42 (gain) which is aligned with the respective saturable absorber mirror 41 along the respective stretch of reflection path and, for example, fixed to it.
• the accumulator 10 comprises deflector elements 50, adapted to intercept the laser beam along the reflection path and at the same time to deflect the direction of the reflected light beam from each of the reflective elements 40 towards a point of convergence O of the reflected light beams.
• the accumulator 10 comprises a target 60, e.g. a capsule made of appropriate material, placed at the point of convergence O (e.g., concentric to it).
• a target 60 e.g. a capsule made of appropriate material, placed at the point of convergence O (e.g., concentric to it).
• a first embodiment shown in the figures from 1 to 5, shows a two-dimensional or flat accumulator, wherein the laser beam is deflected inside the accumulation chamber 30 along a reflection path lying on a travel plane.
• the reflective elements 40 are positioned at the vertices of an imaginary regular polygon.
• the laser beam performs some reflections describing identical chords, until it returns to the starting point in which it was injected in the accumulation chamber 30.
• the imaginary regular polygon is a pentagon (but it cannot be ruled out that it can be a polygon with a number other than five sides) placed inside the accumulation chamber 30.
• the accumulation chamber 30 can be conceived as a "circular billiard table” and the laser generator 20 as a “machine gun” that shoots spherical bullets, on the plane of same, from a point S of its reflection edge, called point of entrance S.
• k is odd and equal to 5
• the accumulation chamber 30 is a cylindrical chamber.
• the accumulation chamber 30, in particular, comprises a cylindrical casing 33, e.g. made of a metallic material such as steel.
• the cylindrical casing 33 has a substantially C-shaped (inverted) cross section, wherein e.g. the central stretch has a height substantially equal to 30 cm and at least one of the end portions (the upper one in the illustration) is shaped like a circular crown, wherein the difference between the outer radius and the inner radius is substantially equal to 20 cm.
• the cylindrical casing 33 can be made by bending a metal section, e.g. 1 cm thick.
• the accumulation chamber 30 also comprises a pair of covers 34, 35, of which a first cover 34 fixed to one of end portions (the upper one in the illustration) of the cylindrical casing 33 and a second cover 35 fixed to the other of the end portions (the lower one in the illustration).
• first cover 34 and/or the cylindrical casing 33 and/or the second cover 35 may have openings which are sealed by removable closure means adapted to the inspection and installation of the internal devices of the accumulation chamber 30.
• the accumulation chamber 30 also comprises a support and centering device 36, e.g. fixed to one of the covers 34, 35 at the center of same, adapted to support the target 60 within the accumulation chamber 30 (in suspension with respect to the inner walls of same).
• the accumulation chamber 30 has an inner diameter substantially equal to 3 meters.
• each saturable absorber mirror 41 is a flat mirror the reflecting surface of which lies on a plane perpendicular to a radius of the accumulation chamber 30 (having a cylindrical shape and therefore circular cross-section) in the reflection point.
• the entrance 31 (and the laser generator 20) is, e.g., positioned at one of the reflective elements 40.
• the laser generator 20 is configured to introduce a laser beam within the accumulation chamber 30 so that this is inclined by the angle a with respect to a diameter of the accumulation chamber 30 and is directed towards a reflective element 40 not adjacent to the reflective element 40 placed at the entrance 31.
• the saturable absorber mirrors 41 positioned at a regular polygon (pentagon), define a closed reflection path for the laser beam, which will follow a broken line (star shaped in the example); onto each vertex (the reflection point of the laser beam on one of the saturable absorber mirrors 41) of the star-shaped broken line converge an incident portion A of the laser beam and a reflected portion B (which becomes the incident portion A for the next vertex along the reflection path) of the laser beam (symmetrical with respect to the radius of the accumulation chamber 30 which passes through the vertex itself).
• a broken line star shaped in the example
• the distance b between two non-adjacent vertices (i.e., the path of each incident portion A and of each reflected portion B) is given by the following formula:
• R is the inner radius of the accumulation chamber 30.
• the deflector means comprise a plurality of deflector elements 50, each aligned with a respective reflective element 40 along the stretch of reflection path in which it is involved.
• each deflector element 50 is interposed between the respective reflective element 40 and the opposite reflective element 40 (i.e. not adjacent to this reflective element 40).
• Each deflector element 50 can be switched alternately between a non-reflection configuration at least with the incident portion A of the laser beam directed on the respective reflective element 40 and a reflection configuration at least with the incident portion A of the laser beam directed on the respective reflective element 40.
• each deflector element 50 in the reflection configuration is adapted to reflect the light beam, e.g., the incident portion A of the laser beam, and to deflect the reflected portion B of same with respect to the reflection path towards the point of convergence O.
• the point of convergence O coincides with the center of the accumulation chamber 30 (and lies on the plane covered by the laser beam).
• each deflector element 50 comprises at least one Pockels cell 51 or equivalent optical element, e.g. an optical crystal of potassium dihydrogen phosphate (KDP) 51. More in detail, in the present treatise the term KDP is the acronym of potassium dihydrogen phosphate.
• the KDP crystal 51 e.g., is connected to power supply means 52 adapted to selectively supply the KDP crystal 51 with an electric field.
• the KDP crystal 51 has the property of rotating the polarization plane by 90° when subjected to intense electric fields.
• These crystals are transparent to polarized light in the same polarization plane of the crystal, while they become reflective to the same light if they change polarization due to the effect of an electric field.
• the KDP crystal 51 is configured to be switched, depending on the intensity of the electric power supply field to which it is subjected, between the non-reflection configuration, wherein it is transparent to the incident portion A (and/or to the reflected portion B) of the laser beam allowing this to reach the reflective element 40 (i.e., the saturable absorber mirror 41) placed at the rear of this, and the reflection configuration, wherein the KDP crystal 51 is reflective with respect to the incident portion A of the laser beam.
• the reflective element 40 i.e., the saturable absorber mirror 41
• the KDP crystal 51 switches from the non-reflection configuration to the reflection configuration, and vice versa in the event of the electric field falling below said threshold value.
• a certain threshold value e.g. positive
• each KDP crystal 51 is arranged inside the accumulation chamber 30 so as to intercept at least the incident portion A of the laser beam.
• each KDP crystal 51 is positioned so that the normal to the reflection plane of the KDP crystal 51 (activated by the electric field) at the point of intersection between the reflection plane itself and the incident portion A of the laser beam is coplanar to the covered plane, coincident with the bisector of the angle ⁇ , the vertex of which is the point of intersection between the reflection plane of the crystal KDP 51 and the incident portion A of the laser beam and is included between the incident portion A of the laser beam and the radius of the accumulation chamber 30 which passes through such point of intersection between the reflection plane of the KDP crystal 51 and the incident portion A.
• each KDP crystal 51 when activated (i.e., reflecting the laser beam) by the electric field, it reflects the incident portion A of the laser beam towards the point of convergence O (the reflection angle of each KDP crystal 51 being equal to the incidence angle and equal to ⁇ /2).
• the KDP crystal 51 is deactivated (or transparent to the laser beam, e.g., in correspondence of a zero electric field or less than said threshold value) the incident portion A of the laser beam passes through the KDP crystal 51 and reaches the saturable absorber mirror 41 from which it is reflected with a reflection angle equal to the incidence angle, i.e., equal to a.
• the saturable absorber mirrors 41 allow the laser beam to describe the closed reflection path repeatedly by accumulating more and more light energy.
• n m * n r +q
• T c m * n r * ATo, neglecting q * ATo because this is a very small percentage compared to T c and does not therefore affect the results, also because it is always best to take n multiple of n r .
• N r m * n r
• the laser generator 20 is of the continuous type and the continuous laser beam is injected inside an accumulator 10 according to the first variation of the first embodiment described above.
• the charging time of the accumulator 10 is a time equal to ⁇ * ⁇ .
• Eo the effective energy of a single light pulse and as x the reflective power of the mirrors
• the residual energy after one, two, three n, ... reflections of the same light pulse becomes Eo*x, Eo*x 2 , Eo*x 3 , . . . , Eo*x n , . . . . respectively.
• the first pulse will have accomplished n-1 reflections, the second n-2 and so on, and the last no reflection.
• the total energy injected into the laser is n*Eo while the total residual energy is equal to the sum:
• the reflecting power plays a key role in the efficiency of the accumulator 10, the amount of charge of which depends directly on it.
• the implosion energy and power are the residual percentage of 12%. In the table below these residual percentages are arranged as a function of n and x.
• This power is significantly lower than that of the individual NIF lasers, the power of which is around 10 12 W.
• This value is one third of the power density of the most powerful NIF laser, density which is equal precisely to 10 15 W/cm 2 , while the energy is one-twentieth of the NIF.
• W e and Ef will also increase; if we increase R, Ef and T c will also increase.
• N r being equal, if we increase the number of saturable absorber mirrors 41 (i.e., n r ), m will also decrease in proportion and therefore the energy of the macro-pulses also decreases. This is beneficial to the fact of not damaging the saturable absorber mirrors 41 with pulses which are too powerful.
• the laser generator 20 having an effective power of about 1 GW, i.e., only 6% of the power of the laser generator of the ILIL center in Pisa and of each of the 192 NIF laser generators, the compression energy obtained is over 315 times that of the NIF, and the power is 380 times that of the NIF.
• the accumulator 10 as sized according to the Example 1.2, obtains an energy 60480 times greater and a power 729600 times greater than each of the NIF laser generators. Finally, it should be remembered that, since the charging time is about 5 tenths of a second, the frequency of implosions is about 120 per minute.
• the pulses reflect on the saturable absorber mirrors 41 at exactly the same time and, after describing the reflection path (star-shaped), they are superimposed on the new pulses which continue to be injected into the accumulation chamber 30 by the laser generator 20.
• the laser generator 20 can be a Mode-Locked laser, but also an super-powerful pulse laser.
• a continuous laser and a pulse laser
• All the considerations and all the formulas described above for a continuous laser may be applied to a pulse laser, being careful to replace the light energy charged on each incident portion A (and reflected portion B) of the reflection path with the energy of a pulse.
• the energy J a of each pulse varies within a very wide range from a few pJ to several tens of Joules for the Mode-Locked lasers, to tens and hundreds of kJ for the super-powerful lasers.
• the supply power W a of the laser generator 20 becomes:
• n m * n r +q
• N r depends on the reflective capacity R of the saturable absorber mirrors 41 and on their resistance to the high energy of light pulses, as has been explained above for the example 1.
• the effective residual energy percentage E r % is calculated in the same way as the continuous laser generator 20.
• the n r macro-pulses after the concentration reflection, converge simultaneously occupying a circular crown which, in decreasing, propagates towards the center of convergence O on the target 60.
• the size of the single elementary pulses is a few micrometers and the number of these is very high, around 10 4 -10 6 , the size of the macro-pulses may be of a few deci- millimeters and so may the size of the circular crown that contains them; it can be assumed, therefore, that the size ⁇ of the circular crown is one millimeter. Consequently the discharge time becomes equal to:
• the ignition power W g to which the surface of the target 60 is subjected is:
• ⁇ can be different from one millimeter and consequently also
• T c is the same in both cases and that also E c and Wf are equal, while W g is greater than W e because At is less than ATo.
• the compression energy obtained by using the accumulator 10 is over 63 times that of the NIF and the power is 10 6 times that of the NIF.
• the frequency of the implosions is about 600 per minute, and therefore fairly high.
• each deflector element 50 comprises at least one mirror 53, e.g. flat, inclined with respect to the reflection plane of the reflective element 40 (i.e. to the reflection plane of the saturable absorber mirror 41) and associated movable inside the accumulation chamber 30, alternatively between the non-reflection configuration, wherein the mirror 53 is misaligned with respect to the direction of the incident portion A of the laser beam along the reflection path allowing the same to reach the reflective element 40 (i.e.
• the saturable absorber mirror 41 placed at the rear, and the reflection configuration, wherein the mirror 53 is aligned with the direction of the incident portion A along the reflection path and deflects, by reflection, the latter in such a way that the reflected portion B by the mirror 53 is directed towards the point of convergence O.
• the mirror 53 is positioned so that, when it is in the reflection configuration, the normal to the reflection plane of the mirror 53 at the point of intersection between the reflection plane itself and the incident portion A of the laser beam is coplanar to the covered plane and coincident with the bisector of the angle ⁇ , the vertex of which is the point of intersection between the reflection plane of the mirror 53 and the incident portion A of the laser beam and is included between the incident portion A of the laser beam and the radius of the accumulation chamber 30 which passes through such point of intersection between the reflection plane of the mirror 53 and the incident portion A.
• each mirror 53 when each mirror 53 is in the reflection configuration it reflects the incident portion A of the laser beam towards the point of convergence O (being the reflection angle of each mirror 53 equal to the angle of incidence and equal to ⁇ /2).
• the incident portion A of the laser beam reaches directly the saturable absorber mirror 41 from which it is reflected with an angle of reflection equal to the angle of incidence, i.e. equal to a.
• the saturable absorber mirrors 41 allow the laser beam to describe the closed reflection path repeatedly by accumulating more and more light energy.
• FIG. 4-5 A possible alternative embodiment of the second variation described above is shown in Figures 4-5 and provides that the mirror 53 be associated in a rotatable manner inside the accumulation chamber 30.
• the cylindrical casing 33 is adapted to support in rotation, for each deflector element 50, a shaft 54 fitted in the cylindrical casing 33 (e.g. radially) at a point near (but not coincident) to a fixing point of the reflective element 40 to the cylindrical casing 33 and supported by appropriate revolving members.
• the shaft 54 has an axis of rotation aligned in plan with the normal median to the reflection plane of the saturable absorber mirror 41.
• the mirror 53 is fixed to the portion of the shaft 54 arranged inside the accumulation chamber 30 in an area moved towards the center of the accumulation chamber 30 with respect to the reflective element 40 and, e.g., locked in rotation together with the shaft itself.
• the portion of the shaft 54 located externally to the accumulation chamber 30 is connected, by means of suitable motion transmission members, to an electric motor 56 configured to actuate the shaft 54 in rotation and then the mirror 53.
• the transmission members for example, comprise gears, of which at least one driving gear 551 associated with the electric motor 56 and at least one driven gear 552 associated with the outer portion of the shaft 54, and a bearing ring 553 with crown gears interposed between them.
• the mirror 53 during rotation of the shaft 54, is adapted to be located in various angular positions, of which at least one in which the mirror 53 is aligned (with respect to the direction of the incident portion A of the laser beam) with the reflective element 40, adapted to define the reflection configuration described above, and at least one in which the mirror 53 is misaligned (with respect to the direction of the incident portion A of the laser beam) with the reflective element 40, adapted to define the non- reflection configuration of the mirror 53 itself.
• the mirror 53 is supported by a wheel 57 keyed on the inner portion of the shaft 54 and defines a discreet radial enlargement of the same.
• the mirror 53 finds itself in at least one reflection configuration interspersed with a plurality of non-reflection configurations.
• the accumulator 10 also comprises synchronization means (not shown) adapted to synchronize the rotation of the electric motor 56 and centering means, so that the mirrors 53 are located all simultaneously at the same time in the respective reflection and non- reflection positions.
• the rotation of the mirror 53 (subtended to the angle ⁇ ) has a duration equal to ⁇ , while the rotation of 2 ⁇ - ⁇ must take place in the time T c .
• the laser generator 20 is of the continuous type and the continuous laser beam is injected inside an accumulator 10 according to the second variation, described above, of the first embodiment.
• An initial check can be made to make sure the values of rotation periods of the mirror 53 are technically feasible.
• N d r and N c r indicate the number of durations of the mirror 53 and also of the new charge time.
• N c r corresponds a new residual percentage E d %
• the shorter discharge time can only be the simple duration ⁇ and the consequent power is given by:
• the star polygons with n r vertices defined by the reflection path of the light pulses, have the sides I which intersect each other inside the circumscribed circumference of the star polygon forming regular polygons with n r vertices, called intersection polygons, as can be seen from figures 16, 17, 18.
• the pulses in covering the reflection path defined by the regular polygon, can encounter at the vertices of the intersection polygon, thereby deviating from their path along the sides of the star polygon.
• P being the length of the perimeter of the star polygon with side t and ⁇ the distance between the two subsequent pulses emitted by the laser source 20, it can occur that two pulses collide at one of the vertices of the intersection polygon.
• the baffle means permit moving the position of the two vertices of a same side from the penta-star polygon plane, called lying plane, leaving the sides unchanged.
• the angle ⁇ is defined as anti-incidence angle.
• Such three-dimensional star pentagon is definable as a regular askew star quasi- polyhedron with anti-incidence angle ⁇ .
• n r + 1 is substituted with 1.
• the vertices of the quasi ⁇ -polyhedron are almost uniformly distributed on the sphere.
• a second embodiment shown in the figures from 6 to 11, shows a three-dimensional accumulator 10, wherein the laser beam is deviated inside the accumulation chamber 30 along a three-dimensional reflection path.
• One of the main characteristics that the three-dimensional accumulator 10 must have is to hit the target 60 (spherical capsule) located within the accumulation chamber 30, with a homogeneous distribution of the laser pulses on the spherical surface.
• the pulses must start simultaneously from the vertices of a regular polyhedron, such as e.g. a tetrahedron, a cube, an octahedron, a dodecahedron, and an icosahedron.
• the reflective elements 40 are positioned at the vertices of an imaginary regular polyhedron, in the example the dodecahedron, placed inside the accumulation chamber 30.
• the accumulation chamber 30 is a spherical chamber (not shown), e.g. made from metal shells (steel), the inner (spherical) surface of which inscribes the imaginary dodecahedron above.
• each segment joining two vertices not belonging to the same face is defined as a diagonal line, from each vertex depart 10 diagonal lines, so the total number of the diagonal lines is equal to 100.
• diagonal lines have three different lengths, i.e. there are three types of diagonal lines, of which a first type defined as short diagonal lines, a second type defined as medium diagonal lines and a third type defined as central diagonal lines.
• the remaining ten lateral vertices are above two horizontal planes which are symmetrical with respect to the center of the dodecahedron and form two regular pentagons, wherein the imaginary segments that join each vertex to the opposite non-adjacent vertices define ten sides identical to the medium diagonal lines d.
• a star-shaped broken line is defined (similar to that of the first embodiment), as shown in Figures 7-9.
• the two star-shaped broken lines and the hourglass-shaped broken line are each made up of segments identical the one to the other and identical to the medium diagonal lines d, precisely five sides for each star-shaped broken line and ten sides for each hourglass-shaped broken line.
• the target 60 is supported (e.g. by support means not shown adapted to keep the target 60 in suspension at the center of the accumulation chamber 30).
• each vertex of each star-shaped broken line and of the hourglass-shaped broken line a reflective element 40 and a respective deflector element 50 are placed, as described above for the first embodiment.
• each saturable absorber mirror 41 is a flat mirror, the reflection (flat) surface of which lies on a plane perpendicular to a radius of the (spherical) accumulation chamber 30.
• a plurality of entrances 31 and a respective plurality of laser generators 20, as previously described, are positioned e.g. at respective reflective elements 40, of which e.g. a first reflective element 40 located at a vertex belonging to one of the star-shaped broken lines, a second reflective element 40 located at a vertex belonging to the other of the star- shaped broken lines, a third and a fourth (opposite) reflective element 40 located at a respective vertex belonging to the hourglass -shaped broken line.
• a laser generator 20 is arranged, in particular, in each of the two star-shaped broken lines and other two laser generators 20 on opposite vertices of a same central diameter of the hourglass -shaped broken line and so that the laser beams emitted from these last two laser generators 20 cover the respective stretch of the hourglass- shaped broken line in the same travel direction.
• Each laser generator 20 is configured to introduce a (continuous or pulsed) laser beam inside the accumulation chamber 30 so that this is inclined by an angle a with respect to a radius of the accumulation chamber 30 and is directed towards a reflective element 40 not adjacent to the reflective element 40 placed at the entrance 31, covering a stretch of the related (star-shaped or hourglass- shaped) broken line it is involved in.
• the saturable absorber mirrors 41 placed at the vertices of the regular polyhedron (dodecahedron), define a closed reflection path for each laser beam, which will follow the related broken line.
• each vertex (reflection point of the laser beam on one of the saturable absorber mirrors 41) converge an incident portion A of the laser beam and a reflected portion B of the laser beam (symmetrical with respect to the radius of the accumulation chamber 30 which passes through the vertex itself).
• the deflector means comprise a plurality of deflector elements 50, as described for the first embodiment, each aligned with a respective reflective element 40 along the stretch of reflection path it is involved in.
• each deflector element 50 is placed between the respective reflective element 40 and the opposite reflective element 40 and aligned with respect to a stretch of the (star-shaped or hourglass- shaped) broken line with the related reflective element 40.
• Each deflector element 50 is switchable alternatively between a non-reflection configuration, at least with the incident portion A of the laser beam directed onto the respective reflective element 40, and a reflection configuration, at least with the incident portion A of the laser beam directed onto the respective reflective element 40.
• each deflector element 50 in the reflection configuration is adapted to reflect the light beam, e.g., the incident portion A of the laser beam, and to deflect the reflected portion B of same with respect to the reflection path towards a point of convergence O.
• the point of convergence O coincides with the center of the (spherical) accumulation chamber 30.
• the deflector element 50 can be of the type shown in the first variation of the first embodiment, i.e., comprise
• Pockels cells comprising KDP crystals 51, or of the type shown in the second variation of the first embodiment, i.e., comprise a movable/revolving mirror 53.
• the accumulation chamber 30 comprises the baffle means described previously to avoid the formation of internal interference between pulses that encounter in the vertices of the intersection polygon. More in detail, in the case of the regular dodecahedron formed of two central pentagons and the hourglass, the baffle means operate on the angles defined in correspondence of at least one vertex of each star-shaped broken line and of the hourglass -shaped broken line varying their relative amplitudes.
• the two pentagons and the hourglass are replaced by quasi-a- polyhedrons so as to eliminate all the intersections of the sides defining the regular dodecahedron.
• two identical two-dimensional accumulators 10 are in practice obtained (defining a respective reflection path along the respective star- shaped broken lines), while along the hourglass -shaped broken line two iso-oriented laser beams are made to accumulate, wherein after five laser pulses (or in any case after every period of time equal to five times the simple duration ⁇ ) there is a pulse above each one of its medium diagonal lines d, as on the segments, of the same length as the medium diagonal lines, of the star- shaped broken line.
• the four laser generators 20 charge the twenty medium diagonal lines of the three-dimensional accumulator 10 (after each period of time equal to five times the simple duration ⁇ 0) forming twenty pulses that at any instant are located on the vertices of a dodecahedron, or at the twenty saturable absorber mirrors 41 (or deflector elements 50).
• the compression energy and the ignition power will be four times greater than those previously described for the two-dimensional accumulator 10 shown in the first embodiment and, in particular:
• Such values are decidedly greater than those needed for the implosion of target 60 made up of a spherical capsule with a diameter of 1 mm containing deuterium and tritium, furthermore they have enough energy and power to obtain the fusion of the nuclei of boron 11 and hydrogen.
• the power density per cm 2 on the target 60 i.e., a spherical capsule with a diameter of one millimeter, is substantially equal to:
• the pulses themselves are distributed evenly on an adequate surface of the apparatuses, until the last reflection, and finally are made to converge on the target 60.
• the inner surface of the appliance being a spherical surface
• the shock wave from the implosion of the target 60 is reflected converging in the center of the sphere, with the possibility of producing the implosion of a new target 60 specially located in the center of the accumulation chamber 30.
• subsequent implosions of a plurality of targets 60 are then obtained in a natural and automatic manner without using a suitable implosion laser.
• the reflecting apparatuses used in the previous treatise are substantially of two types and precisely: simply reflecting apparatuses and entrance reflecting apparatus.
• the simply reflecting apparatuses each consist of a highly-reflecting mirror which generally speaking can be a simple highly-reflecting plate or an (isosceles) prism with total double reflection with angles at the base ⁇ and at the vertex ⁇ , as described in Figure
• These prisms, or the reflecting plates, are located in the vertices of the star polygon of the appliance as described in figure 1, excluding the vertex S where the injector Laser assembly is arranged.
• the graph in Figure 19 permits determining the formulas between the refraction and reflection angles of an isosceles prism with angles at the base ⁇ and angle at the vertex ⁇ . Let 1 be the limit angle of the prism and
• the reflected beam forms, with the normal n c in C an incidence angle co. Furthermore, the external angle in L of the triangle LCB is the same as ⁇ , consequently we have:
• Said angle indicates the deflection undergone by the incident beam i to exit from the prism.
• the entrance reflective apparatus is located, on the other hand, in the vertex S of the polygon where the injection laser is also installed.
• a first resolution embodiment of said apparatus is that it is formed of a semi-reflecting mirror similar to that used in almost all lasers.
• a further type of embodiment is that formed of an isosceles prism with total double reflection, the same as the previous ones, but shaped in such a way that the faces crossed by the injected beam are perpendicular to it, as shown in Figure 20.
• the beam of the laser RL is parallel to the exiting beam RU and distant from it by a few micrometers, a distance indicated by ⁇ , but in such a way that the exit point D is always on the natural face of the prism.
• the entrance reflective apparatus located in the vertex S must be reflective to laser pulses from inside the accumulation chamber 30 (in more detail to the left of the vertex S), and must in turn be transparent (refracting) to the pulses from the laser generator 20.
• the entrance reflective apparatus must be simultaneously both reflective to laser pulses from inside the accumulation chamber 30 and transparent to the laser pulses from the laser generator 20, but this would produce an interference which results in a diffusion of the two laser pulses deflecting them from the direction along the chord of the star polygon causing the accumulator 10 to malfunction.
• n r the number of vertices of the star polygon, to n r also corresponds the number of reflections required by the pulse to describe the entire polygon;
• the distance between two subsequent pulses is given by ⁇ and is:
• the initial pulse emitted by the laser generator 20 returns to the vertex S.
• Diophantine system in the integer variables n r , P, C.
• This example being that of a small-size laser generator, the cycle of which contains 35 laser pulses, requires a high number of cycles N c to accumulate high energies.
• a laser pulse is needed with energy between 3 MJ and 5 MJ and to power a powerful electric turbine, a frequency of implosions fi m is required between 1 Hz and 10 Hz.

Landscapes

• Physics & Mathematics (AREA)
• Engineering & Computer Science (AREA)
• Plasma & Fusion (AREA)
• General Engineering & Computer Science (AREA)
• High Energy & Nuclear Physics (AREA)
• Lasers (AREA)

Applications Claiming Priority (2)

Publications (1)

Family

ID=53053015

Family Applications (1)

Country Status (2)

Families Citing this family (1)

Family Cites Families (4)

• 2016
  • 2016-02-09 WO PCT/IB2016/050678 patent/WO2016128895A1/en active Application Filing
  • 2016-02-09 EP EP16712486.6A patent/EP3257049A1/de not_active Withdrawn

Also Published As

Similar Documents

Legal Events