DE2500429A1 - Fusion reaction by three stages of laser bombardment - with increasing energy and shorter duration also reflectors for second stage - Google Patents

Abstract

A method of operating a thermonuclear reactor consists of introducing heated, liquid lithium from a heat exchanger tangentially into a pressure vessel, then abstracting it from the vessel back to the heat exchanger, so as to form a central cavity in the pressure vessel, thermonuclear fuel pellets are intermittently, individually fed into this central cavity and bombarded by a laser beam to initiate a fusion reaction, the fast neutrons thus produced breed tritium in the liquid lithium, this tritium being removed in the heat exchanger, the heat produced in the heat exchanger drives a steam turbine to generate electricity. The laser beam is subdivided into successive pulses, a first pulsed beam oriented directly into the cavity zone on the path of the fuel pellets and having a selected energy and duration (esp. 1-2 Joules and 10-8- 10-9 secs) to evaporate and slightly ionise the pellets and thus form a plasma, a number of second, pulsed laser beams immediately following the first pulse and reflected from surfaces below the plasma to 'tailor' the plasma, these having a higher energy and shorter duration than the first beam (esp. 200-400 J and 10-8 -10-10 secs) a third pulsed high-energy firing laser beam having a still higher energy and still shorter duration (esp. 105J and 10-9-10-11 secs) and oriented directly into the 'tailored' plasma, to cause a fusion reaction inside it. Each of these steps is repeated for each individually introduced fuel pellet to obtain an optimum energy output level. Cryogenic magnetic fields are not required. Damage to the vacuum wall of the reactor by fast neutrons is substantially eliminated. A tritium breeder ratio greater than unity is obtd.

Description

Programmed laser beams for the optimal generation of fusion reactions In fuel pellets it is known that the sun generates energy through thermonuclear Generates reactions which take place at very high temperatures. These reactions and all controlled thermonuclear reactions are based on collosions between Cores to release energy.

It can be shown that extremely high temperatures must be reached, to get usable thermonuclear power, but at these temperatures the energy loss due to radiation is also great. Deuterium and Tritium release and emit energy at relatively low temperatures relatively little radiation, making them suitable as thermonuclear fuels are. The containment of the fuel at such temperatures was in some Arrangements according to the prior art achieved in that one very strong magnetic fields provided which included the containment vessel for the fuel; different procedures were previously provided to the density of the ions of the fuel and their energy so that the ions undergo fusion reactions to form high-energy neutrons to create. In known reactors operating with deuterium as fuel Usually a jacket is provided for the reactor vessel for breeding tritium and to convert the kinetic energy of fusion neutrons in includes recoverable heat, the latter in a conventional heat cycle is used to generate electricity. Such a coat must have three basic principles Meet Nuclear Power Engineer Requirements: He must hatch tritium, i.e. tritium based power economy is not possible if the rate of tritium production in the mantle does not exceed the rate of consumption in the fusion plasma; 2. the mantle must have the kinetic energy of the fusion neutrons n - as mentioned above- converting recoverable heat; 3. The coat must withstand structural failures and corrosion at operating temperatures and with neutron irradiation built to be stable be; some of the problems with the known devices are the proper ones Enclosure of the thermonuclear reaction products by very strong magnetic fields and the high costs involved in the diffraction of such fields; furthermore the Heating the thermonuclear fuel to high enough temperatures to ensure that the thermonuclear reactions occur; the provision of means to ensure that the density of the heated fuel is sufficient is great to overcome the various loss processes involved in generating of a high temperature plasma; and finally, rapid neutron damage the vacuum wall of the container, in which the thermonuclear reactions take place.

Most of the above problems were caused by the system according to the U.S. Patent Application Serial No. 10 516 dated February 11, 1970 (inventor: Arthur P. Fraas owner: US Atomic Energy Commission) eliminated. With this registration, pellets are made frozen thermonuclear fuel, e.g. deuterium-tritium, periodically and individually into a central void of a rotating body made of liquid lithium injected. The void in liquid lithium is most conveniently created by that Litium is injected tangentially into a pressure vessel, thus creating a central one To create a vortex or an empty zone.

Each of the pellets is bombarded with an intense laser pulse, when the pellet is essentially trapped in the void of the liquid lithium is to produce the fusion, and thus to cause the heating of the lithium. The heated lithium becomes a heat exchanger and tritium recovery system transported, after which the lithium is returned to the reactor pressure vessel.

To the by the successive ignition of each of the frozen Pellets shock waves generated by the pulsed laser beam on the reactor pressure vessel wall appropriately entrapping gas bubbles in the lithium streams become infected, when it is transported back into the pressure vessel by the heat exchanger. The liquid one Litium with the gas-bubbles which the central one generated within the pressure vessel Surrounding void serve not only as a tritium brood mantle, but also as a a means for absorbing the shock wave forces of the periodic within the void generated thermonuclear reactions and as a means of substantial mitigation or elimination of damage from fast electrons on the pressure vessel walls, so that there is no need to prefer magnetic fields outside the pressure vessel, to contain plasma.

It was determined from energy calculations that the efficiency of the System of the above application is below what is desired. For example is the equilibrium point where the energy output of the system equals the energy input to the laser, of such a nature that the overall efficiency of the system improves would have to be if this were possible. The present invention improves on that in the system described above in such a way that the operating efficiency is improved in a manner to be described below.

The invention aims at a thermonuclear reactor system as indicate a procedure that would normally be required to contain the plasma Eliminates cryogenic magnetic fields that damage the vacuum wall of the reactor fast neutrons essentially avoids having a trinity flute ratio of greater generated as 1, provides an optimal energy transfer to the thermonuclear fuel and generates more electrical power than is consumed in a more efficient way Way when operating the reactor.

The above purpose is achieved according to the invention, that a system is provided which is essentially that in the above Registration is similar, but instead of a single high-energy laser pulse to perform the fusion within the injected fuel pellet at least three consecutive uses pulsed laser beams of different energy and duration, all being such jets on each of the sequentially injected fuel pellets is directed in such a way that optimal energy is directed to each pellet Purposes of ionization, density shaping ("tailoring") and fusion is transferred. By Using such sequential pulsed laser beams according to the invention was found that the total input energy required to generate the pulsed laser beams to produce the aforementioned optimal energy transfer to each of the pellets is about two orders of magnitude lower than that for a single pulsed Laser beam as used in the above-mentioned application, so that the above-mentioned Equilibrium point is significantly improved, resulting in more efficient operation of the present reactor system compared to the system of the above-mentioned application has the consequence.

It should be noted that at the University of Rochester, N.Y.

conducted research by the inventors used a system wherein a single laser pre-pulse, without the tailoring pre-pulse, before the main ignition laser pulse was used, with the main pulse having an appropriate duration and energy of up to to 2 x 103 joules. The present invention employs two Pre-pulses and a main ignition pulse up to 1.5 x 105 joules in one way to be descriptive.

Further advantages, objects and details of the invention result in particular also from the subclaims and from the following description of Embodiments based on the drawing; In the drawing: Fig. 1 shows a Drawing showing schematically the basic working principles of the present Invention represents; 2 shows a representation of the calculated total neutron production as a function of time using the system of Figure 1; Fig. 3 is a schematic Illustration of the system of Figure 1 used in a thermonuclear Reactor system. The basic principles of operation of the present invention are shown in FIG. The arrangement according to FIG. 1 can be used together with a pressure vessel of a thermonuclear reactor system As shown for example in Figure 3 and in described below, or with any of the reactor pressure vessels described in the in the aforementioned application. In Fig. 1 is a laser source on one side of a fuel pellet 12, for example deuterium-tritium, arranged. The laser source can have sequential laser pulse beams of different Generate energy and duration in quick succession. It should be noted that also separate Laser sources, if desired, can be used to generate the sequential (consecutive) Generate laser pulse beams. The pellet 12 is approximately 3-10 in size mm and is by any suitable means, for example by evaporative cooling, cryogenic cryostats, etc. and is shaped into the position shown in FIG entered suitable means not shown, for example by an electrostatic Lens or a system that resembles a Zi-el pellet cannon. While that Pellet 12 is in this position, an initial laser pulse is generated by the source 11 13, which does not need to be very focused, is generated and aimed at the pellet, where the pulse 13 is a Energy of about 1 - 2 joules and one Has a duration of approximately 10 8 to 10 9 seconds. This impulse causes the evaporation of the pellet 12 and weak ionization of the resulting vapor.

A second group of pulses 14 with an energy of approximately 200-400 joules and a duration of approximately 10 8 to 10 10 seconds is through the source 11 generates; these impulses are focused on the weakly ionized plasma, from different directions, and generally opposite to Direction of the first pulse 13, for example from the corners of an equilateral Polygon arrangement made of reflective surfaces 16, such as this for example is shown in Figure 1, where this polygon represents three directions. The impulses 14 immediately follow the pulse 13 and are used to introduce pressure waves used, which in their propagation inwards a dense formation ("tailor") and cause an enclosure of the plasma.

The result is a versatile pyramid of concave surfaces with high density, with the base consisting of plasma, the density of which is sufficient is low to allow penetration of subsequent laser radiation.

Immediately after the pulse 14 there follows a last focused laser pulse 15 from source 11, which is directed into the base of the above-mentioned pyramid, around the Ignite density-tailored (tailor) plasma. This last pulse has 15 the energy of about 10 joules and a duration of about 10 9 to 10 11 seconds and is aimed at the plasma in the same direction as the first laser pulse. The resulting fusion reactions continue after this last impulse continues until it is terminated by expansion of the plasma.

After this occurs, the above steps are repeated and again repeated for each subsequent pellet injected until the operation should be switched off.

As mentioned above, all pulses from a laser source can be at suitable control will be delivered and it are mirrors used to generate the second multiple sequential pulses 14. By using the initial first and second preparation pulses in the system of FIG the required energy of the main ignition pulse of approximately 107 to 108 joules, an amount that is required in the single laser system of the above-mentioned registration, to about 105 joules or possibly less in the present invention lowered.

For the above-described evaporation, plasma cutting and sequential D-T combustion thermonuclear process was a two-dimensional computer code written. It was used to determine the neutron output during the D-T combustion part as a function of time.

The result for a particular set of parameters is in Figure 2 shown. The parameters for this calculation were: pellet size, 5 mm; entire Pre-pulse duration (1st and 2nd

Impulse), 2 x 10 9 sec .; Total pre-pulse energy, 383 joules; Ignition pulse duration, 1.5 x 10 10 sec .; Ignition pulse energy, 1.5 x 105 Jules. A point of equilibrium where the energy output of the system exceeds the energy input to the laser, is shown in FIG. The absorption process in the plasma heating mechanism is complete collision, and accordingly it is assumed that the value of 105 joules is a conservative estimate of the minimum energy required for effective operation is. It should be emphasized that the above process is basically because of the very high thermal Electron conduction will work, which the input energy much faster spreads than-any asymmetries can develop.

In Figure 3 there is shown a manner according to which the above-described Process can be used in conjunction with a reactor vessel, including the Auxiliary components are shown that are used to generate electricity from the thermonuclear Serve fusion reactions. For example, as shown in Figure 3 is a reactor pressure vessel 20 provided, which is 12.5 feet in diameter and a wall thickness 10 inches in diameter and made of, for example, steel alloy or Nioh exists. The vessel 20 is provided with a tangential inlet 26 for introduction liquid Litiums fitted to a swirling body of Litium 31 with a central empty area 32 to generate. In practice there can be several such lithium inlets used to define the empty area with a given shape, e.g. constant Diameter to form. A second inlet 21 is for the injection of the fuel pellet assemblies 33 provided and for the laser beams coming from a laser source 11, wherein also a lithium outlet 22 axially with the second inlet 21 and the axis of the void 32 is aligned. An external fuel pellet feed system not shown is provided to periodically generate a plurality (one at a time) of pellet arrays 33 to inject or enter into the empty area 32 of the pressure vessel 20. It it should be noted that the laser source 11 'is much further away from the pressure vessel, than shown in the drawing, and that the fuel holding assembly 33 is much smaller than shown for clarity; further the inlet 21 is constructed in such a way that it is not only large enough is to allow the input of individual arrangements 33, but that he is also a clear line of sight for the pulsed laser beams 13 ', 14' and 15 'from the source 11 'to the fuel pellet 36 as shown. For example, the inlet be oval.

The fuel holding assembly 33 has an aerodynamically shaped one Jacket 34 and a rearwardly facing cavity 35. Inside this cavity 35 a pellet 36 of, for example, frozen D-T fuel is arranged, the is supported on a pedestal (support column) 37. The lower part of the cavity 35 is shaped so that it forms mirror surfaces 38 in order to reflect the laser beams 14 '. The surfaces 38 can be portions of a conical surface, or can be individual be flat surfaces. As an alternative to the above structure, each of the fuel pellets with a cover be provided that peeled off to the rear, after the first laser pulse occurs, the more reflective surfaces for the Deflecting the second multiple laser pulses 14t onto the fuel pellet to form.

The circuit of liquid lithium of the system of Figure 3 is thereby completes that the outlet 22 is connected to a heat exchanger 23, the output of which is in communication with a pump 24 to return the lithium to the Inlet 26 to be fed. Since it is important to have gas bubbles in the liquid lithium 31, A source of inert gas 25 can be connected to the pump 24 and with tangential Nozzles in the pressure vessel or at other convenient points in the system. It should be noted that the system can also be made without the addition of gas bubbles of inert gas if desired can be operated, the walls of the pressure vessel being thicker in such a case would be made. However, gas bubbles are preferably used. The heat exchanger 23 is with a tritium recovery system and with an electrical one not shown Generator system connected in the same way as this in the above Patent application (now U.S. Patent No. 3624239).

It should be noted that the liquid lithium at the start of operation to the desired operating temperature by any suitable not shown Agent is heated in a conventional manner.

Litium is being pumped through the at a rate of 1,400 gallons per minute The reactor vessel is pumped with sufficient gas added to maintain the mean density to be reduced to about 5%. The operating temperature of the lithium is set to, for example held approximately 9000F - 18000F depending on the material used in the pressure vessel.

When operating the system of Figure 3, the arrangements 33 are with their frozen fuel pellets 36 placed one at a time in a position like them is shown in the drawing in the empty zone 32, at this point in time the sequential pulsed laser beams 13 ', 14rund 15t with the corresponding energy levels and durations equal to that of the laser beams of the figures I can be directed sequentially at the pellet 36 for optimal ionization, plasma density formation and to effect fusion of the fuel. This sequence of pellet feeding and that subsequent aiming of the laser beam thereon will be at selected intervals repeated from 1 to 30 seconds. It should be noted that each assembly 33 is completely is disassembled before another such arrangement is injected into the pressure vessel or is entered.

The resulting release of energy is generated by the fusion reactions an approximately 100 ° Ft rise in lithium temperature, resulting in the production of 50 - corresponds to 1,000 MW of thermal energy. The circulating lithium then transports some of this heat in the heat exchanger23. This heat can be used for this become a working fluid for a Rankine circulatory system for cooking or to heat a gas for a Brayton circulation system in usual way.

It should be noted that the inlet 21 of the pressure vessel is quite long with an inner wall profile can be made from a variety of baffle plates and it was done in the same manner as in the aforementioned US patent. These Training is provided to dampen the explosion wave coming through upwards runs through inlet 21 and through each of the fusion reactions within the pressure vessel is effected; this design also prevents any splashing up of the liquid to the opening. It should also be noted that after each fusion reaction, the rotational moment in the lithium in the pressure vessel supports the restoration of the empty zone, since the lithium throughput in a typical case is so large that about 50% of the Litiums in the vessel are replaced in each cycle. The above mentioned flow rate of the heated liter of 1,400 gallons per minute through the reactor keeps the average Temperature rise in lithium to about 100 F during operation, which is desirable is to keep the thermal loads at a low level.

The heated liquid lithium circulating through the reactor with its inert gas bubbles not only serve as a cushion for the waves of the explosion, generated as a result of the thermonuclear fusion reactions that occur in the Ignition of each pellet may occur, but it also serves as a means for incubation of tritium and to capture the energy of fast neutrons in the form of Heat as a result of the slowing down and absorption of neutrons in whatever way any radiation damage to the reactor pressure vessel wall is minimized. Since also the thermonuclear reactions essentially completely through the heated, liquid Lithium instead of metallic walls, as is normally the case in known reactors is done, there is no need for any magnetic fields to Enclosing the reaction products, as these are essentially flowing through the liquid lithium are shielded. The overall tritium breeding ratio of the system of Figure 3 is approximately the same as in the above-mentioned US patent, i.e. it is at least 1.5.

A recovery system connected to the heat exchanger 23 of the tritium, which in the liquid lithium 31 when flowing through the reactor pressure vessel 20 of Figure 3 is generated and an electrical generator system associated with it is described in the aforesaid patent and it is referred to at this point Referenced.

As already mentioned above, the above-described can according to the invention System with any of the reactor pressure vessels of the aforementioned patent - if desired - Be used, where various means are shown to the flow of liquid lithium through each of the various reactor pressure vessels shown to effect.

The present invention has essentially the same advantages like the system of the above patent. For example, is the pressure vessel capital cost The neutron economy is much lower than for reactors with magnetic fields of the present system is excellent, since one routinely achieved a tritium pulp ratio of at least 1.5, the present invention would be most suitable for propulsion systems of ships because a considerable Reduction in size and weight of the pressure vessel as well as a reduction of nuclear safety problems occurs. In addition, the present invention is more economical than known systems as they require less power input for the laser source is required to reach the above mentioned equilibrium point, which results in more efficient operation and compared to the known system allows an increase in the energy output variable of at least 100 times.

It should be noted that the present invention is not limited to the use restricted by frozen (solidified) deuterium-tritium pellets; she can too using frozen deuterium pellets or using frozen D-3He pellets, if desired, can be performed.

It should also be noted that the present invention does not apply to the Use of liquid lithium per se is limited, but also using it a liquid lithium beryllium fluoride compound or other lithium containing Connections can be practiced.

Claims (7)

PATENTAN 5 P RUCHE A method of operating a thermonuclear reactor, in which heated liquid lithium tangentially from a heat exchanger into a pressure vessel fed in, then fed back from the pressure vessel to the heat exchanger, in such a way that a centrally arranged void zone is formed in the pressure vessel, periodically Thermonuclear fuel pellets are entered individually into the empty zone and a Laser beam in the empty zone in the path of the individually inserted fuel pellets is directed to cause its fusion reactions, and by the at These reactions produced fast neutrons tritium in the liquid lithium is carried out inside the pressure vessel, which is removed in the heat exchanger is, and wherein the heat removed from the heat exchanger to operate a steam turbine used for electricity generation is characterized in that the laser beam is divided into a plurality of successively ignited laser pulses, wherein a first pulsed laser beam 13 'of a selected energy and duration directed into the empty zone in the path of the individually entered fuel pellets will cause the evaporation and weak ionization of the pellet to form a plasma to effect, whereupon a plurality of second pulsed laser beams simultaneously 14 'immediately following the first pulsed laser beam with a second selected one higher energy and shorter duration than the first pulsed laser beam into the formed plasma by a plurality of reflective surfaces 38 below of the formed plasma directed to effect a density shaping of the plasma is, and wherein a third pulsed high energy ignition laser beam 15 'with a third select continues to have much higher energy and continue shorter Length of time as the second laser beams are directed directly into the density-shaped plasma is immediately following the plurality of second laser beams to To cause fusion reactions within the densely formed plasma in the void zone and wherein each of said steps of sequentially aligning the first, second and third pulsed laser beams into each of the successive ones individually entered fuel pellets is repeated in this way a to obtain optimal energy output from the reactor. 2. The method according to claim 1, characterized in that inert gas bubbles be introduced into the liquid lithium before this is fed into the pressure vessel will. 3. The method according to claim 2, characterized in that the frozen Fuel pellets made from essentially deuterium-tritium, deuterium and deuterium- 3He formed group is selected. 4. The method according to claim 3, characterized in that the selected Fuel pellets are deuterium-tritium, 5. The method according to claim 4, characterized in that that the first laser pulse beam has an energy of 1-2 joules and a duration of 10 8 to 10 9 seconds that the group of the second pulsed laser beams has an energy of 200 to 400 joules and a duration of 10 8 to 10 10 seconds, and that the third pulsed laser beam has an energy of approximately 105 joules and has a duration of up to 10 seconds. 6. The method according to claim 5, characterized in that the flow rate of liquid lithium through the pressure vessel to a speed of approximately 1,400 gallons per minute is maintained and that the operating temperature of liquid lithium is maintained at a selected value in the range of 9000F to 1.8000F will. 7. Fusion reactor in particular according to one or more of the preceding Claims characterized with a pellet of thermonuclear fuel material by at least one laser, means for generating a timed sequence of Laser pulses with successively increasing energy, means to reduce the energy from the first directing the said impulses to one side of the pellet from a first point, to vaporize the pellet and ionize the vapor to form a plasma, Means to transfer the energy of a second of said pulses to the plasma of to focus at least 3 spots from 3 spots on the opposite side Side of the plasma opposite the first point to shape and shape the plasma enclose, and by means of, the energy of a third of the impulses upon the Plasma from a location on the same side of the plasma as the first location directed to ignite a thermonuclear reaction in it. L e r s e i t e