by Acad. Yevgeny VELTRhOV, President of the National Research Center "Kurchatov Institute"; Acad. Fyodor BUNKIN, Director of the Research Center of Wave Studies, RAS Prokhorov Institute of General Physics; Pavel PASHININ, RAS Corresponding Member, Chairman of the Expert Council of the Russian Fund of Basic Research; Yevgeny SUKHAREV, research adviser of Designer General, R&D Association "Almaz" named after Acad. Raspletin; Moscow, Russia

This country began work on high-power laser back in the early 1960s. "It could be possible to create 10⁶-10⁷ J generators by using a common explosive as an energy source...," said Nikolai Bassov, Deputy Director of the Lebedev Physics Institute, in December of 1963 in his letter to Acad. Mstislav Keldysh, President of the national Academy of Sciences, in response to a Defense Ministry request to assess the possibility of laser military uses. Even though laboratory tests showed -10 J pulse generators as the only workable ones in those days, the idea of high-energy lasers did not seem far-fetched at all.

The decision to develop high-power laser systems came from Dmitry Ustinov, chief of the Soviet military-industrial complex. In 1965 he called the first conference on this subject with the participation of Alexander Prokhorov and Nikolai Bassov (both Nobel prizewinners of 1964, elected full members of the Soviet Academy of Sciences in 1966). Prokhorov suggested to proceed from neodymium-doped glass lasers being developed at the Physics Institute (FIAN) at the time. Such lasers were found efficient enough (2-3 percent efficiency) and provided for good output of radiation per unit of length. Together with Acad. Alexander Raspletin, a great authority in the field of radio engineering who laid a groundwork for Russian anti-aircraft missilery, Prokhorov and Bassov put forward an idea of using such lasers in air defense systems against low-flying objects. This idea won support from the CPSU Defense Department and the Government's Military-Industrial Commission. The government decision to this effect was off in 1967. As a guideline for the effort of creating a laser complex for immobilization of air targets, it set deadlines and appointed a task group responsible for this work.

Alexander Prokhorov was in charge of the scientific part of the project. For its practical realization he enlisted the Moscow-based Strela design office (the Almaz R&D Association today), an enterprise specializing in ack-ack rocket complexes, the backbone of our air defenses. Laser systems were the domain of a department set up for the purpose. As Designer General, Raspletin put in charge of this work his deputy, Boris Bunkin, awarded two gold stars of Hero of Socialist Labor (first in 1958, and then in 1982) for his signal services in the making of combat systems of weaponry, high-energy lasers including. The project came off well thanks to his practical experience.

Proceeding from the cumulative energy of splinters of a model ground-to-air missile head, he calculated the amount of energy necessary for hitting an air target. A laser weapon, Raspletin figured, should have as much as 10 M J on target, the value of its energy momentum. Adequate facilities like optical devices, radars, lidars and precise beam targeting systems were needed for that. It became possible to cope with all these tasks thanks to a broad-based cooperative involvement of executors. In the early 1970s we already had an experimental setup of neodymium-doped glass laser with an energy momentum of 100 kJ and comprising four modules--as many shots were needed to hit an air target for sure.

Its designers had to deal with hard engineering problems, for one, neodymium-glass cooling. At first they were unable to come on top of it because of the cylindrical form of the glass. So the form of the glass had to be changed into that of a large "tie" or "sleeper". The adequate manufacturing technology was developed by Dr. Igor Buzhinsky, head of the optical glass factory at Lytkarino, Moscow.

Pump tubes likewise posed a problem--their first specimens exploded while contacting one another in compact systems. Therefore these tubes and their constituent elements had to be designed anew.

An adequate power supply source was also high on the agenda. Getting together with Raspletin, Prokhorov and Acad. Mikhail Millionshchikov in charge of the MHD generators* program, we examined a number of options and finally decided on a self-excitation magnetohydrodynamic generator supplied with an inductive charge integrator, quite suitable for this laser type--inducing a constant current, it generated an efficient energy momentum.

The power supply assignment was supervised by the Kurchatov Institute of Atomic Energy (the National Research Center "Kurchatov Institute" today). The MHD setup was to be designed and manufactured by the Gorky (Nizhni Novgorod) engineering plant.

It was found possible to make use of solid (powder) plasma-generating fuels. Acad. Boris Zhukov, the progenitor of solid-fuel rocketry in this country, became interested in the idea. His Moscow-based Research Institute of Chemistry and Technology carried out tests to determine the power and electrophysical characteristics of plasma powders, i.e. the plasma generators for MHD setups.

Magnets, high-current devices and inductive charge integrators were manufactured at the Yefremov Research Institute of Electrophysical Equipment in Leningrad (St. Petersburg) under the supervision of Vassily Glukhikh**, an authority in the field of electro-

* See: V. Shafranov, "Beyond the Pale of What Is Known", Science in Russia, No. 1, 2010.--Ed.

** See: V. Glukhikh et al., "On the Brink of Thermonuclear Era", Science in Russia, No. 3. 2003.--Ed.

physics, magnetic hydrodynamics of liquid metals and controlled thermonuclear fusion. The generator components (a 100 MJ electromagnetic excitation system as well as an inductive charge integrator and 200 kA-50 kV switching equipment) are still the world's unique.

By the close of 1968 Zhukov had gotten prototype plasma-generating powders having the conductivity of combustion products ~10⁴ as high as conventional solid rocket fuels. These facilities went into the making of an independent self-excitation impulse MHD generator, the Pamir (IM-1), whose power was ~10 MW. It was built in 1969 at the Gorky engineering plant. The assigned parameters of the setup were checked in field tests demonstrating that the basic principles of M H D generator design and assembly had been mastered, and one could go ahead with quantity production. Subsequently the IM-1 developed into a series of independent pulse generators with one, two and three ~5 to 15 MW channels. The largest, Sakhalin (channel power, as much as 600 MW; time of operation, up to 10s) was built in 1975. The experience gained in running smaller setups of this kind was used thereby. The successful performance of this "giant" generator confirmed the technical feasibility of short-term MHD generation at ~1 GW in open cycles with rocket engines. The Sakhalin setup demonstrated record-high values of the MHD interaction parameter (~1 MW) and unique specific characteristics some of which are unattainable yet. Such generators opened up the possibility of power supply for special systems operating on novel physical principles.

And yet this laser system, though providing the required power level for destroying airborne targets, was too cumbersome and thus could not be used in battlefield conditions.

New compact high-efficiency CO₂ lasers touched off a new cycle of works in developing high-energy gener-

ators for hitting airborne targets. This job was carried out at the Kurchatov Institute and its daughter enterprise at Troitsk, Moscow (the Troitsk Institute of Innovative and Thermonuclear Research today). In particular, this enterprise was dealing with generators operating on a homogeneous discharge in a gas flow. This work was directed by Dr. Vladimir Baranov representing the school of Professor Benjamin Granovsky of the Department of Physics of Moscow State University.

He and his team had to address the key problem of glow discharges within a large space, the commonest kind of d.c. gaseous discharges. These were found good for CO₂ laser pumping, for the greater part of liberated energy went for excitation of molecular oscillations: a plasma-confining electrical field imparted its energy to electrons, the carriers of the smallest negative electric charge, and these excited oscillations. Nitrogen (N₂) is especially good for this purpose capable of converting as much as 95 percent of energy into molecular oscillations initially. Present in the mixture was also helium (He) speeding up heat rejection, for a large amount of heat was released thereby. Finding an optimal proportion of the components CO₂-NO₂-He was hard nut to crack. And yet the main problem was to excite and accumulate energy in nitrogen when present on the electrodes was a current density initiating contraction (compression of the gaseous discharge), while a different density was there within the ambient space. So one had to find some middle ground and combine both properly. This problem was solved in the end. The first high-flow CO₂ laser was created at Troyitsk; it had an independent discharge of its own in which energy was pumped and accumulated in nitrogen, whereupon carbon dioxide (CO₂) was injected. This 1 MW setup could generate continuous coherent radiation, for it was at work as long as the gas flow was there.

Another variant of attaining high-energy characteristics was laser pumping by a beam of charged particles. We did this work in collaboration with the FIAN Physics Institute (Acad. Alexander Prokhorov), Moscow State University (Dr. Alexander Rakhimov) and the Kurchatov Institute (Dr. Vyacheslav Pismenny). Our model experiment on the effect of a beam of fast protons on CO₂ laser generation showed the use of the energy of charged particles was more effective in this case than electric power. The results of that experiment were published in the journal Letters to ZhETF'm 1968. (Subsequently an attempt was made to pump the laser by nuclear fission fragments; yet stiff safety standards ruled out this line of research as too risky.)

Independent charge lasers were found to be of higher efficiency on account of the separation of the two functions--ionization by fast charged particles and nitrogen pumping (different electrons, different energies). So by separating both from each other, we tangibly improved both the stability and the quality of the discharge. Thus we improved its efficiency as well. All that made it possible to build setups in which a beam of electrons ionized a gas flow at 1 atm pressure, whereas in independent lasers this indicator was equal to 1 atm (whereupon contraction set in).

Simultaneously other research centers were working on the laser hardware. In 1973 Prokhorov and Bunkin got the Central Design Office Almaz to develop high-power gas dynamics lasers conceptualized by Bunkin and making it possible to obtain radiation directly from the MHD generator. In addition he tackled another very difficult problem of an optical guidance and targeting system that allowed to focus a laser beam on the most vulnerable spot of the target. Thus a video laser radar, the lidar, came into being. Its screen showed a target image, not a target reference.

All these facilities were tested on mobile arms systems. A setup was mounted on board a combat aircraft generating one megawatt of continuous radiation, while the Americans used a small-yield 300 kW chemical laser placed aboard the same flying vehicle. A CO₂ laser was installed on a naval ship to protect it against cruise winged missiles. Carmounted ground systems performed just as well, too. They were equipped with an original radiation generator: its synthetic mirror could focus a beam over a long stretch and make up for atmospheric effects (this technology is in wide use in astronomy for manufacturing composite telescopes).

So at Bunkin's initiative and under his guidance industrial and research institutions joined hands to cope with a variety of most difficult research, technological and managerial problems in setting up national air defense systems on the basis of high-energy lasers of different types--solid, gaseous, gas dynamics and independent discharge lasers. Scientists, designers, engineers and military experts demonstrated laser beam targeting systems ensuring sure-fire destruction of targets. The United States developed similar complexes only in this past decade. However, the Soviet Union's breakup led to a collapse of the cooperative effort in the early 1990s and killed respective projects.

And yet the experience gained in the warmaking sector found spinoffs in civilian areas. Thus, MHD generators came to be used right away in major geophysical and geological surveys, also in geophysical prospecting by electric means. Reconfigured and customized, there appeared Pamir, Ural, Khibiny and Precaspian MHD setups mounted on automobile chas-

sis. In 1973 one such generator was taken to a geophysical proving ground in Central Asia, 200 kilometers away from Dushanbe, Tajikistan, in the north of the Pamir Mountains, where the Schmidt Institute of Physics of the Earth was busy with research in earthquake prognostication. Later on MHD generator-aided studies of the earth crust were continued at the testing ground of the Institute of High Temperatures at Bishkek, Kirghizia. Geophysicists had as many as 114 MHD-assisted sessions. The statistical evaluation of the sounding results obtained there showed an electromagnetic pulse is capable of "fragmenting" the incipient major quakes into a series of weaker tremors, thus making it possible to use such setups for an artificial relieving of tectonic stresses.

In 1980 a Baranovled team designed a commercial CO₂ laser of periodic pulse action for selective technologies. It performed well at the Research Institute of

Stable Isotopes in Tbilisi, Georgia. In 1997 experts of the Russian Research Center "Kurchatov Institute" supported by the Gazprom Corporation built and commissioned in the city of Kaliningrad an industrial complex for mass production of ^l3C-tagger pharmaceutical drugs. Its technology and equipment are without peer elsewhere in the world. Its laser unit is capable of putting out as much as 15 kg of carbon isotope. Its output can further be boosted by separated laser siblings to supply the country's medical institutions with low-cost products (half as much of the world cost).

In 1979 the national government passed a decision on further work on technological lasers and establishing a research center at Shatura, Moscow (in 1998 reorganized into the RAS Institute of Laser and Information Technologies). It was a big step of the government and Academy of Sciences toward conversion programs, all the more so as defense industry enterprises turning

out laser hardware were to provide complete sets (electronics, optics, mechanics). The young research center took up such fields novel in this country as laser "line-of-force" technologies and assimilation of new promising uses for processing plants supplying biomedical preparations, too. The core of its research collective had an excellent background of work at the Kurchatov Institute, the Moscow Bauman College of Technology, Moscow State University and the RAS Institute of Spectroscopy at Troyitsk, Moscow.

The Shatura center has a set of workshops, including a unique optics shop in adaptive optical devices substantially improving emission quality. By the early 1990s it developed high-power commercial CO₂ lasers of a second generation; it came up with as many as 200 computerized complexes and tested scores of processing and machining technologies; furthermore, it carried out basic research projects in microtechnology.

The integration of information and laser processes made it possible to turn to medical instrument-making. The research center conceptualized remote bio-modeling that allowed to feed through Internet computer-assisted tomography data on patients at different clinics prior to surgery to the Shatura center of stereo-lithography.* Such preliminary information allows to obtain, within just 10 to 20 hours, polymer copies of the skeleton and organs, thus helping surgeons plan ahead the scenario of an operation and adequate strategies and tools. The Shatura center has developed laser stereolithographic setups and launched their production. This is its greatest achievement. This equipment makes it possible to manufacture high-precision plastic copies of industrial parts from three-dimen-

* See: M. Khalizeva, "Lasers in Science, Technology, Medicine", Science in Russia, No. 3, 2011.--Ed.

sional computer models, and do it fast. It can make a full-size plastic model of a turbine blade, including channels for a coolant's feeding and even a wind-tunnel aircraft model, though scaled down.

Metal cutting and welding are the most common spinoff of lasers in industry. One spectacular example is a laser-aided setup for welding cardan shafts at the Likha-chev Automanufacturing Plant in Moscow in 1980. Such welding accounts for a better weld quality compared with the argonarc technology. The Likhachev automanufacturers introduced the technology of a laser-assisted thermal packing of heads in a truck that allowed to double its service life.

Lasers are being used in the nuclear industry for cutting and welding the fuel channels (Kursk Nuclear Plant) and in the oil-and-gas industry, for welding large diameter gas pipes. The weld quality is greatly improved thereby.

Russia's economic modernization is the overriding objective today. Yet her modernization should rely on certain models, laser technologies for one,-all the way from the gestation stage up to full-scale laser-based production. Our people, our research scientists have made major headway in such technologies. Drawing upon our experience, we are capable of achieving the goal of national modernization.