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UV/VUV Lasers with REB Pumping

#1977


Investigations of Ultraviolet and Vacuum Ultraviolet lasers with Runaway Electron Beams Pumping

Tech Area / Field

  • PHY-OPL/Optics and Lasers/Physics

Status
3 Approved without Funding

Registration date
22.08.2000

Leading Institute
Institute of General Physics named after A.M. Prokhorov RAS, Russia, Moscow

Supporting institutes

  • VNIIEF, Russia, N. Novgorod reg., Sarov

Collaborators

  • Northeast Science & Technology, USA, MA, East Sandwich\nUniversity of Twente / Department of Applied Physics, The Netherlands, Enschede\nLos Alamos National Laboratory, USA, NM, Los-Alamos

Project summary

Lasers operating in UV and VUV spectral range are widely used in microelectronics, medicine, etc. Presently, excimer lasers are most powerful sources of coherent radiation available in UV and VUV range. However, they have serious drawbacks, e.g., the presence of corrosive or toxic gases in active medium, quick degradation of working mixture, need for using spectral-purity noble gases at pressures of a few atmospheres. Thus, special precautions must be taken for environmental protection and complicated cleaning, gas pumping, and regeneration systems must be used, which makes excimer laser systems too complicate, cumbersome, and expensive.

Interest is paid to production of new, reliable, and highly efficient UV and VUV lasers operating with pollution-free gas media. Solution of this complicated problem by conventional pumping sources, relativistic electron beam or self-sustained electric discharge is impossible due to extremely difficult realization of the first approach and low efficiency of the second one. The present project suggests principally new approach to solving the problem stated and is based on pumping of laser by runaway electron beams (REB).

Molecules of chemically inactive gases, such as N2, H2 and ions of noble gases Ne, Kr, Xe, etc. are capable of generating laser radiation in UV and VUV spectrum range. In the project we suggest runaway electron beams for efficient pumping of these gases. In this case, the pumping electron beam of the energy ~10 KeV is produced directly in the active medium at relatively low accelerating voltage (of the order of tens kilovolts). The principal advantage of this approach is simple realization and handy exploitation, which is inherent in electric-discharge pumping systems. In addition, systems with electron-beam pumping can efficiently excite high electron levels of UV and VUV lasers. Moreover, runaway electrons with the energy 1–10 keV exhibit considerably higher rate of gas ionization as compared to relativistic electrons or electrons produced in self-sustained discharge, which is important for increasing the output power of gas lasers. Hence, pumping of gas lasers by runaway electrons is a most promising way in laser physics, which opens wide prospects for further development of lasers, in particular, lasers operating in UV and VUV spectral range.

The project is aimed at investigation of a new method of pumping by high-power runaway electron beams and creation of efficient sources of coherent UV and VUV radiation on this basis. The active media of such lasers include ecologically safe gases, such as hydrogen, nitrogen, helium, and other noble gases.

In order to achieve the goal stated, it is necessary to carry out complex investigations and to solve some fundamental and applied problems. The fundamental investigations of the project are based on theoretical and experimental study of the origin of runaway electrons, mechanisms of their transportation across the discharge gap, interaction with active medium, and features of laser generation development in these conditions. Particular attention will be paid to REB in pulse-periodic lasers operating at the repetition frequencies up to ~ 1 kHz.

Results of the fundamental investigations will make a basis for solving application problems and creating model units of highly efficient and reliable N2, H2 -lasers and ion lasers of new generation operating in UV and VUV spectrum ranges.

In addition, we assume to estimate prospects for REB application, e.g., in pumping gas lasers of visible and infrared ranges, other laser crystals, in preionization systems for gas lasers, etc.

Scientists from GPI RAN (Moscow) and RFNC-VNIIEF (Sarov) are involved in the presented project. Principles of exciting molecular lasers by high-power runaway electron beams elaborated by our specialists and their rich experience on creation of UV lasers are prerequisites for successful fulfillment of the project. Investigations in this field are conducting in GPI RAS since middle 90-th and include the development of pulsed sources of runaway electrons with the energy 1÷10 keV, beam current density 103 A/cm2, and the pulse duration 10-9–10-7 s operating at the pressure of molecular gases up to ~100 torr. They also include choice of laser media and search for optimal conditions of their excitation. The priority results have been obtained on generation of high-power UV laser radiation in nitrogen excited by REB (V.V. Apollonov, V.A. Yamschikov, “Investigation of runaway electron beams for pumping of UV range gas lasers” Proceedings of SPIE, “High Power Lasers” 3889 (2000), p.739 – 748, Osaka, Japan; V.V. Apollonov, V.A. Yamschikov, “High power UV nitrogen laser with runaway electron beams pumping,” Technical digest of International conf. On LASERS’99, p.3, Quebec, Canada). Scientists from VNIIEF are the authors of pioneer works on investigations of runaway electrons (L.P. Babich and Yu.L. Stankevich, “Criterion of a transfer from the streamer mechanism of gas discharge to continuous runaway electrons,” [in Russian], Zh.Tekhn.Fiz. 42, No.8 (1972) pp.1669–1673; A.I. Pavlovskii, L.P. Babich, T.B. Loiko, and L.V. Tarasova, “Runaway electrons in gas discharge and origin of the minimum U(pd),” Doklady Akad. Nauk SSSR, 281, No.6, (1985) pp.1359–1363). Wide experience in creating high-power IR and UV lasers acquired in last years is a guarantee for successful fulfillment of the project at high scientific and technical level (V.V.Apollonov, V.A.Yamschikov, “On the efficiency of electrodischarge N2- laser,” Kvantovaya Elektron., 24, No.6 (1997) pp.483–486; V.K. Bashkin and A.B. Treshchalov, “High Repetition Rate Excimer Laser Directly Pumped by a Sliding Discharge,” CLEO “Europe-98”, Technical digest, (1998) p.355; B.V. Lazhintsev, V.A. Nor-Arevyan, and V.D. Selemir, “Electric Discharge Lasers with Plate Electrodes and Stabilized Discharge,” Proceedings of SPIE, “High Power Lasers” 3889 (2000), p.732 – 738, Osaka, Japan; B.V.Lazhintsev and V.A.Nor-Arevyan, Patent of Russia No.2105400 of 12.11.96, Isobreteniya, No.5 (1998) p.481).

The results obtained in the course of project carrying out will be of considerable scientific and commercial value. They will provide creation of highly efficient and ecologically safe UV and VUV lasers pumped by REB in addition to new fundamental knowledge in physics of laser and laser discharge.

Wide experience of scientists of RAS in carrying out fundamental investigations on the one hand and specialists of RFNC-VNIIEF involved in nuclear weapon program with great experimental basis on the other hand will provide successful solution of the problem stated.

The project will be fulfilled in collaboration with foreign partners. Regular information exchange is supposed on current problems of the project, in particular, discussions of the results obtained and organizing joint seminars. Total amount of information obtained in the course of the project carrying out will be available for the foreign partners.

Realization of the project will make it possible for specialists of RFNC-VNIIEF to concentrate their efforts on civilian problems and use scientific-technical potential of the institute to peaceful purposes. The results obtained will be published and available to a wide range of scientific community and reported in international conferences. This will provide further integration of scientists of RFNC-VNIIEF into the world scientific community.


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