October 8 2013 at the Lawrence Livermore Laboratory (a leading US nuclear research center) on the NIF laser facility for the first time in stories managed to ignite a thermonuclear reaction with a "positive energy output." The installation is a huge factory floor in which the 192 pulsed laser is mounted, 12 years and four billion dollars were spent on its construction.
The thermonuclear target was compressed by a laser pulse with an 1,8 energy of MJ. This is the highest energy level of a single laser pulse that has ever been obtained. Achievement is outstanding. The previous record holders - the Soviet 12-channel installation "Iskra-5" and the American NOVA - generated respectively 30 KJ and 40 KJ impulse. The main Soviet divisional gun of the period of the Great Patriotic War, the famous ZIS-3, had the energy of a single shot at 1,43 MJ. The gun weighed one and a half tons, was distinguished by simplicity and dependability. The anti-aircraft gun of the same caliber (51-K arr. 38) had a shot energy in 2,2 MJ, but it also weighed significantly more - 4,3 tons.
The most powerful continuous-wave laser ever created was the American Alpha, developed by TRW in the late 80s. This chemical hydrogen-fluorine laser with a design power of 2 MW weighed 45 tons, had a length of 24 meters and a width of 4,5 meters. Close to this power (from 1,5 to 1,7 MW) had single-barrel aviation guns developed in the mid-50s: American M-39, English Aden, French Defa. The weight of all three guns (excluding the weight of ammunition) was approximately the same: 80–82 kilograms.
The most massive air gun of the US Air Force was (and remains to this day) the six-barreled 20-mm M61 "Vulkan", it was put on all fighters, it is also in the stern defensive installation of the strategic bomber B-52. The power of the gun is 5,3 MW, the energy of a single shot is 53 KJ, the weight with the projectile feed system is 190 kilograms, the weight of the entire system with ammunition in 1200 shells is about 0,5 tons. In other words, the "Volcano" is 90 times lighter than the "Alpha" and 2,5 times more powerful.
As far as can be judged by open publications, the most successful of the practically implemented Soviet laser programs was the flying laboratory A-60. This is a heavy cargo plane IL-76, on which units of a powerful gas-dynamic laser were installed. Probably, it was a product of the Voronezh design bureau “Himavtomatika” (under this vague name hid one of the best developers of liquid rocket engines in the USSR), which had the intra-designation RD-0600. On the official website of the KB are its characteristics: radiation power - 100 kW, weight - 760 kilograms, dimensions - 2 x2 x0,6 meters.
However, 760 kilograms is only a radiator with a nozzle device. In order for the device to work, you need to bring to it a “working body”, that is, a stream of hot carbon dioxide under high pressure. Two AI-24 turbojet engines with 2550 horsepower and 600 kilograms each were used as a gas generator. Thus, only these two units (emitter and gas generator), without taking into account everything else (nitrogen cylinders, kerosene for aircraft engines, gas pipelines, aiming optics, instruments of the control system) weighed about two tons. A similar output power (98 KW) had the legendary Soviet aviation 7,62-mm ShKAS machine gun - on the eve of the war they were armed with fighters I-16 and I-153, it was also used as a defensive weapon on the SB and DB-3 bombers. Machine gun weight (without ammunition) was only 11 kilograms.
"Dazzling, thin, straight, like a needle, a beam ..."
Such chains of examples can be continued for a long time, but, as practice shows, what has already been said is enough to bring the lazomanov to a deeply inverse state. “How can you compare a machine gun and a combat laser?” They will shout. “Machine guns shoot hundreds of meters, and the laser beam almost instantly hits targets at a distance of hundreds and thousands of kilometers!”
Thought interesting. Let's count. “Fine, like a needle,” the ray of the hyperboloid of engineer Garin remained at a distance determined by the size of the room at the hotel “Blackbird” - and in this sense Alexei Tolstoy did not sin against scientific truth. At large distances, the fundamental physical law of diffraction divergence begins to clearly manifest itself. There are no thin rays; any optical radiation that passes through a finite-sized “window” is an expanding cone. In the best, ideal case (the active medium of the laser is absolutely homogeneous, the energy input to the medium is also absolutely uniform) the half-angle of the light cone is equal to the partial angle from the division of the wavelength by the diameter of the output window. And now we take a photo of a laser emitter, presented on the site of Khimavtomatika Design Bureau, take a calculator and calculate a little.
The wavelength of a carbon dioxide laser is known exactly - 10,6 microns. The size of the output aperture of the radiator can be “by eye” defined in 15, see. This, by the way, is an excellent result - usually the dimensions of the active zone of gas-dynamic lasers are measured in units of centimeters. Further simple arithmetic shows that already at a distance in 10 km the base of the radiation cone will have (at best, with a divergence equal to the diffraction) diameter in 1,5 m and area in 18 thousand square meters. cm. At a distance in 100 km - 15 m in diameter and 1,8 million square meters. cm square. It is on this huge “spot” that 100 KW of laser output power will be spread.
At a distance in 100 km, the power density in 0,06 W per square meter is obtained. see. Such a "sizzling beam" can be obtained from a flashlight. At a distance of 10 km, 5,6 W per square meter is obtained. see. This is already quite noticeable - but we need not to warm up, but to break the design of the enemy’s aircraft or cruise missile. There are various estimates of the thermal energy required to destroy a target; they all fall within the range from 1 to 20 KJ per square meter. cm.
For example, for the complete evaporation of 1 sq. cm sheet of 3 mm thick need to be “pumped” into it 8 – 10 KJ. The bullet on departure from the barrel AKM carries about 4,4 KJ per square. see. But even the smallest of the mentioned figures (1 KJ) means that laser “shooting” at a distance of 10 km will require holding the radiation spot on the target for 160 seconds. During this time, the subsonic cruise missile will fly 45 km - unless it is shot down on the way from the good old ShKAS.
"In the blue haze melts ..."
The remarkable "efficiency" of a laser weapon obtained in our conventional example can have something to do with reality only when the action takes place in a cosmic vacuum, and the target is a "black body" (it absorbs everything, does not reflect anything). In the atmosphere, everything works much worse, and experts have long known. From open publications it is noteworthy, for example, a report on a study conducted by the American Naval Research Laboratory. Americans were interested in the fate of a laser beam propagating in the surface layers of the atmosphere at more than a modest distance of 5 kilometers.
The fact that the order of 60 – 70 percent of the beam energy is lost “on the way” to the target is not surprising, such a result could be expected in advance. Much more interesting than the other. The graphs obtained by Americans for the dependence of the energy delivered to the target on the laser output power firmly indicate that there is a certain “threshold” of radiated power, upon reaching which any further increase in laser power does not lead to any increase in the impact on the target: the beam energy will be wasted to heat the smallest dust particles and water vapor in an increasing and larger volume of the “air channel” along the beam path. Moreover, in the desert or above the sea this “threshold” is in the 2 – 3 MW range, in the atmosphere of the modern city the threshold power is limited to 200 – 250 kW (these are typical output parameters of a large-caliber machine gun). There is no interesting thing in the published research results - how will the laser beam propagate over the battlefield, enveloped in clouds of smoke and dust?
A concrete idea of the real possibilities of lasers can be given by the experience of practical use of the mobile technological installation MLTC-50, created on the basis of 80's military developments. This is a CO2 gas laser pumped by an electric discharge, operates in a frequency-pulse mode, the energy of a single pulse is 0,5 KJ, the maximum output power is 50 KW. On energy slightly inferior to the German infantry machine gun MG-42. Installation takes two car trailers with a total weight of equipment 48 tons. However, these dimensions and weight do not include the most important thing - an external power supply with a power of 750 KW. In July, 2011, the complex was used in the liquidation of a fire in a gas well, when it was required to remotely cut steel structures that prevented emergency operations. All were successfully cut at a distance of 50 – 70 meters with a focused beam at an absolutely fixed target, having spent only 30 hours of total laser work on this (the whole operation took six days). I remember Garin dealt with the Aniline Company plant faster ...
Brief summary: there is no place for ground-based and / or air combat for “power”, “destructive” laser weapons. A weak beam will not have a noticeable effect on the target design, a strong “smeared” on atmospheric dust and moisture. At medium and even farther distances, the efficiency of a “laser gun” is negligible; in the near zone, air defense tasks can be much more reliably solved by traditional means (high-speed anti-aircraft guns and guided missiles) that are hundreds of times lighter and cheaper. For defense of minor objects, laser air defense is unacceptable. For the protection of strategically important objects, weapons, whose effectiveness depends on dust, rain and fog, are fundamentally unsuitable.
The naked truth of "star wars"
At this point, the dream of "lazermans" are carried high, into the vast expanses of space, where there is no noise, no dust, no absorption, no defocusing of the laser beam - there "laser guns" will unfold to their full power ... Here we will begin with power (power).
There are two fundamental laws of nature that no “breakthrough technologies” can undo. This is the law of conservation of energy and the law of increasing entropy ("the second law of thermodynamics"). A laser is a device in which natural chaos turns into highly organized, coherent and monochromatic light, such a transformation cannot in principle be carried out with high efficiency. The best among the worst is a chemical laser, that is, a device in which the energy of an exothermic chemical reaction directly turns into coherent radiation (bypassing numerous intermediate stages: from heat to mechanical movement, from movement to electricity, from electricity to a light pulse pumping a laser medium). But even for a chemical laser, achievable efficiency is limited to a few percent. And this ultimately means that a laser emitting 5 – 10 MW will heat itself and the surrounding space with a power of 100 – 150 MW.
The indicated power (100 – 150 MW) is the power supply of a small city, it is the main propulsion system of the nuclear aircraft carrier. In order for the “laser gun” to not instantly melt, such gigantic heat flows must be removed somewhere from it. For a product working on the Earth, this task is difficult both scientifically and technically, but still solvable. And how to get rid of so much heat in space?
Outer space is a thermos. Such a thermos is normal, only the distance between its “walls” can be considered infinite. Even for existing spacecrafts, where the cosmonauts' bodies and working electronics (almost zero compared to the heat emission of a high-power laser) are internal sources of heat, cooling is probably the most difficult task for designers. What will happen to this station if a megawatt-class chemical laser starts working inside it?
Yes, difficult does not mean impossible. We will place the equipment sensitive to overheating in a separate module, separated from the laser module for a couple of hundred meters, attach heat-emitting panels the size of several football fields to the laser compartment, make these panels roll up so as not to overheat from the sun's rays, we will shoot from the “laser gun” only during the flight in the shadow zone ... Problem solved? Not. Now we are waiting for another meeting with the laws of geometrical optics, but already at new, cosmic distances.
Even in the case when a combat space station is launched into low near-earth orbit (rather than hanging on a geostationary station at a distance of 36 thousands of kilometers from the Earth), the “laser shooting” range required to defeat the launching ICBMs of the enemy is measured in thousands of kilometers. The Americans, in the era of the Strategic Defense Initiative announced by Ronald Reagan, threatened to launch into space 18 military stations with a range of 5 thousands of kilometers. Then begin the simplest exercises in school arithmetic.
In order for a long 10 seconds to transfer to the body of an enemy missile at least 1 KJ per square meter. cm, it is necessary to ensure the power density on the target 100 W per square. see And this means that the radiation of a space laser with a monstrous five-megawatt power (recall that no one has done this even on a ground stand) should be compressed into a “spot” with a diameter of no more than 2,5 meters. With a range of 5 thousands of kilometers and a 2,8 μm radiation wavelength (chemical hydrogen-fluorine laser), this will require a telescope with a mirror diameter of at least 7 meters. If, however, to reduce the time of impact on the target to 0,5 seconds (as was envisaged in the plans of "star wars"), then the mirror will need 32-meter. Are there any other questions?
Shield and shield
The largest optical mirror, which at this time was able to bring into space, was the main mirror of the American Hubble telescope with a diameter of 2,4 meter. This miracle of technology was polished for two years, having the task of achieving the accuracy of a parabolic shape with an error of no more than 20 nanometers. But they made a mistake, and on the edge of the mirror the error was 2 micron. These microns have grown into a huge problem, for the solution of which I had to make "glasses", which were delivered into space and attached to a defective mirror.
The diameter of the 2,4 meter mirror is, of course, not the limit of technological capabilities. Back in the distant 1975 year, the Soviet telescope BTA-6 (at that time and up to 1993-th - the largest in the world) with the diameter of the main mirror 6 meters was commissioned. The blank for making the mirror cooled down after the glass was melted for two years and 19 days. Then, when polished, it was ground into 15 dust of thousands of carats of diamond tools. The finished “pancake” weighed 42 tons, the total mass of the telescope with the details of the mechanical drive - 850 tons.
Yes, for space, you can make it easier, having met not hundreds, but only tens of tons (by the way, the small Hubble weighed 11 tons). But then new questions arise, one more interesting than the other. What is the nail and why should the cosmic mirror be nailed so that it is stabilized in space with angular accuracy in the fraction of microradian? How will the impact of the positioning of the mirror affect the release of a huge amount of working fluid from a megawatt chemical laser? What can be practically a mechanical drive system that rotates a multi-ton mirror in space after a target moving with hypersonic speed (the launching ICBM in the upper atmosphere)? What to do if the enemy ICBMs take off at the wrong distance, based on which the optics were focused?
The most important thing is what will remain of the nanometer-shaped accuracy of the mirror after a megawatt laser beam passes through it? Immutable physical law says: "Every laser beam has two ends." And the energy at the far end of the beam, on the target, can never be greater (in fact, it is always less) than that concentrated in the laser emitter. If the “heat spot” in the 2,5 meter on the target melts and destroys the target, then what will happen to the mirror, whose area is only 8 times larger? Yes, the mirror reflects almost all laser radiation brought to it, but who said that the target will reflect much less?
Bad news for "lazermanov" is that the main material for the covering of rockets and aircraft is aluminum. The reflection coefficient for infrared radiation with a length of 10,6 μm (gas-dynamic CO2 laser) is close to 100 percent. In the emission range of chemical lasers (1 – 3 μm), aluminum reflects about 90 – 95 percent of the beam energy. What prevents to polish the rocket trim to a mirror shine? Wrap it with aluminum foil? Cover with a thin layer of silver (in comparison with the enchanting cost of a megawatt space-based laser is mere pennies) ... You can take another way: do not polish the MBR lining to shine, but on the contrary, coat it with an ablative (heat-removing) coating. This technology has been worked out half a century ago, and with rare tragic exceptions, the descent vehicles returned safely to Earth, having experienced heat loads at the entrance to the atmosphere that are two to three orders of magnitude superior to everything that promising laser guns can create.
"Reason in spite of, in spite of the elements ..."
The elementary truths and elementary calculations given above should be known to any bona fide student. Specific figures of the radiation power required for hitting a target could have been obtained already in the early years of the “laser era.” The only thing that was not known from the very beginning was the physics of the propagation of high-power laser radiation in the atmosphere. But this question was also removed after the end of the 70-s in both the USA and the USSR created and tested (on the ground and in the air) gas-dynamic lasers of the 100-kilowatt class.
By the beginning of the 80-ies, the absolute futility of "power", "destructive" laser weapons did not cause doubts among the specialists employed in this field. However, it was then that began the laser madness. 23 March 1983, US President Reagan has publicly announced the Strategic Defense Initiative (SOI), under which it was supposed to create a system of space-based laser weapons capable of destroying the launching ICBMs by the hundreds. What was it? The most common version today is that the SDI was from the very beginning a grand bluff, with the help of which the Americans tried to drag the USSR into a new, unbearable round of the arms race. Whether it is true or an afterthought to make a good face on a bad game - no one will give an unequivocal answer. One thing is known for sure: the IDF developers fooling their own heads with delight of inspiration.
6 September 1985 of the year in the framework of the next “demonstration of technologies” chemical laser on hydrogen-fluorine with a power of about 1 MW destroyed the corps of the second stage of ICBM “Titan”. The spectacular picture was scrolled through all TV channels, the Director of the Office of IDF, Lieutenant General James Abrahamson, gave interviews to enthusiastic journalists: "The laser smashed this thing literally to pieces ... Very, very impressive." And the truth is - where is it even more spectacular? They promised to create a system capable of burning the 5 range of thousands of kilometers across the hull of the launching ICBM in 0,5 seconds. In fact, the target was at a distance of 800 meters from the radiator, no one knows the time to “fry”. The hull was inflated with excess pressure from the inside and loaded with compression vertically, that's why it scattered into pieces. About the size and weight of the laser system, about the deactivation device of the poisonous fluoride "exhaust" the size of a hangar, the general delicately kept silent ...
Then the same megawatt MIRACL laser was transferred to the deck of a warship and announced that the BQM-34 subsonic simulated cruise missile was hit by a laser beam. Delight knew no bounds. Later, however, it turned out that the shooting was carried out at a distance of less than a kilometer (where an anti-aircraft gun unit would successfully cope with this task), while the laser did not burn or break anything, but only “damaged the electronic components of the control system, as a result why the target lost its stability and broke. ” What kind of "components" were disabled by a heat ray and whether it is not a question of self-destructing by the command of an IR-sensitive sensor - the story is silent for now. It is only known that the command of the US Navy considered it a blessing to remove the poisonous laser machine from the ship and did not return to the question of its use.
Meanwhile, the bona fide experts' patience broke, and in April 1987 was published (whatever one may say, but the 1-I amendment to the US Constitution is strictly observed) a report on 424 pages prepared by a group of 17 experts from members of the American Physical Society. Politely (the SDI program was still announced by the president), but it was firmly said that “the discrepancy between the current stage of development of weapons of directed energy and the requirements for it is so great that to achieve the goals, it is necessary to eliminate major gaps in technical knowledge.” In particular, “chemical lasers need to increase the output power by at least two orders of magnitude (ie, a hundred times!) Compared to what has been achieved ... free electron lasers require testing several physical concepts and their power must be increased by six orders of magnitude. .. methods for correcting the optical quality of a laser beam need to be improved by many orders of magnitude ... "The final conclusion:" Even under the most favorable circumstances, ten or more years of intensive research will be needed before it is possible children to make an informed decision (to make a decision, not to put the system into service!) about the possibility of creating a laser beam weapons and missile defense for solving problems. "
"By the mistakes of the fathers and by their late mind ..."
In 1993, the SDI program was officially closed. Finita la comedia? Not at all. The smell of the budget pie continued to excite the appetite, and the “peaceful respite” lasted only three years. In 1996, a new scam has begun. Now the chemical oxygen-iodine laser (radiator weight - 9 t, output power - 1 MW) with a mirror with a diameter of 1,6 meter was to be installed aboard the transport giant Boeing В-747. To begin with, 1,1 has allocated a billion dollars in budget. Then, of course, they added, in just 16 years, 5 billions of dollars were invested into the ABL program.
At this time, the role of a "magic wand" capable of overturning the laws of the universe, claimed the so-called adaptive optics. What was done by American engineers is really amazing. The huge mirror was divided into 340 elements, each with its own mechanical drive. A system of two “diagnostic” kilowatt-power lasers continuously probes the atmosphere, another subsystem analyzes the wave parameters of a high-power laser, the computer issues control commands, and the curvature of the main mirror is adjusted at a rate of a thousand times per second.
All these efforts and billions of dollars in costs were crowned with a report in which it was stated N times: “Dust particles in the atmosphere lead to energy absorption and erosion of the beam, reducing the effective range of damage. In addition, the dust particles burning in the beam create IR interferences that impede accurate aiming. A weapon cannot be used if a cloud appears between the laser and the target. ” The final paragraph of the phrase should be cast in granite: "Physics are translated from English means:" It is difficult to deal with the laws of nature. "
Nevertheless, in exchange for 5 billions, it was necessary to knock something down. The technical assignment assumed the destruction of launching ICBMs at a distance of 20 – 40 kilometers during a single 300 – 400 departure, with a target cost of “a few seconds” of radiation. After a series of unsuccessful attempts, it was finally possible to knock down a flying ballistic missile with a liquid-fuel engine. This landmark event occurred on February 11 2010. The developers honestly admitted that they failed to burn through the target plating, but the weakening of the structure as a result of heating turned out to be enough to destroy the rocket in flight. The heat generation of the megawatt laser was sufficient to cool the “laser gun” before the next “shot” within an hour. The second attempt to knock off a rocket taking off (this time a solid-fuel rocket) was unsuccessful due to "beam misalignment". Perhaps, in this case, the problem was the unacceptable overheating of the radiator and the mirror.
That's it all over. The program was officially closed. US Secretary of Defense Robert Gates addressed the developers with these words: “I don’t know anyone in the Department of Defense who thinks that this program should or can be quickly deployed. The reality is that you need a laser 20 – 30 times more powerful in order to hit the launch missiles at the proper distance. To put this system into action, we need to have 10 – 20 aircraft carrying 1,5 billion dollars apiece with a maintenance cost of 100 million dollars per year, and I don’t know a single person in uniform who would believe that such a concept can be workable. "