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Laser beam evaluation methods to study changes in 12 MeV energetic protons irradiated glasses

M-R IOAN1, I. GRUIA2,* , G-V.IOAN1, L. RUSEN3,2, P. IOAN1, A. ZORILǍ3,4

Affiliation

  1. "Horia Hulubei" National Institute of Physics and Nuclear Engineering - IFIN HH, 30 Reactorului Str., 077125 Mǎgurele - Bucharest, Romania
  2. Physics Department, University of Bucharest, 405 Atomiştilor Str., 077125 Mǎgurele - Bucharest, Romania
  3. ISOTEST Laboratory, National Institute for Lasers, Plasma and Radiation Physics, 409 Atomiştilor Str., 077125 Mǎgurele - Bucharest, Romania
  4. "Politehnica" University of Bucharest, 313 Splaiul Independenţei, 060042 Bucharest, Romania

Abstract

In most applications, optical windows or lenses are the bridges between the laser systems and the real environment and are often subjected to hostile conditions. The purpose of this work is by applying laser beam diagnosis techniques (two methods) to study changes of transparent glass properties induced by their irradiation with strong ionizing radiation (e.g. the high energy proton irradiation may be used to simulate the damage caused by neutron and gamma irradiation, and this way we avoid the difficulties involved with nuclear reactor irradiations. Basically, we investigated the changes due to the colour centres’ or other defects produced by irradiating borosilicate glasses with 12MeV energetic protons. In principle we can expect to changes in the transmittance properties of these glasses and for larger-size induced defects even an increase in their scattering properties, or a change in the spatial profile of the laser beam used as a test beam. Several Tempax glass samples were irradiated using the IFIN-HH- 9MV High Voltage Tandem Van de Graff accelerator irradiation facility at a dose rate of about 1.2kGy/s +/- 8% and an average energy of 12 MeV. Energetic and spatial beam characterizations, according to ISO 11554 and ISO 11146-1 standards, were performed on a low power He-Ne laser beam (linearly polarized), before and after passing the beam through each irradiated glass sample. According to the changes in the glass transmittance, the value of the absorption coefficient was determined for several samples (70.11% relative increase). Spatial beam characterization was performed to see whether or not there are changes in the internal structure of glass samples, shown by the varied values of the beam propagation factor M2. In our case, the experimental set-up has highlighted a relative decrease of the initial laser beam power of 25, 95% on the entire range of absorbed doses (0÷108) KGy. At the same time we showed a relative increase in the coefficient of propagation (M2) of 7.16% geometrical method) and 9.27% (fit.

Keywords

ISO- Standard, laser beam, He-Ne laser, Optical glass, High proton energy, Degradation of transmission.

Submitted at: June 10, 2013
Accepted at: Nov. 7, 2013

Citation

M-R IOAN, I. GRUIA, G-V.IOAN, L. RUSEN, P. IOAN, A. ZORILǍ, Laser beam evaluation methods to study changes in 12 MeV energetic protons irradiated glasses, Journal of Optoelectronics and Advanced Materials Vol. 15, Iss. 11-12, pp. 1403-1411 (2013)