A. P. Sergeev

Electron-beam induced absorption in crystals of the alkaline-earth fluorides

The absorption behavior has been studied in the 120-1000-nm region in modern high-purity samples of MgF2,CaF2, and BaF2 crystals when they undergo prolonged irradiation in air by an electron beam with energy less than 280 keV (about 104 pulses, total fluence about 20 kJ/cm2). The induced optical density in CaF2 and BaF2 in the 200-1000-nm region was about 0.04-0.1 after such irradiation. Absorption in the UV region in MgF2 samples monotonically increases with irradiation, and they have almost completely lost their transparency in the 260-nm region at fluences of about 500 J/cm2. The studies of the crystals showed that the electron-beam induced absorption is largely determined by impurities that were either already present or that entered the samples while they were being irradiated.

E-beam-induced absorption in various grades of quartz

The comprehensive results are presented on the behaviour of high purity synthetic quartz glasses under the action of intensive ionizing radiation (x-rays and energetic electrons) and UV laser radiation with 248-nm wavelength. They are concerned to the application of e-beam-pumped large-size KrF-laser as a driver for the Inertial Fusion Energy.

How the absorption-band intensities in high-purity quartz glasses depend on the electron-beam fluence

To study the formation of defects in quartz glasses of type KS-4V, KU-1, and Corning 7980 under the action of an electron beam (EB), the induced absorption spectra is decomposed into individual bands (IBs) with maxima at 163.5, 183.5, 213, 225, 244, and 260 nm. In all the glasses, the intensities of most of the IBs saturated at doses around 90 MGy as the EB fluence increased. The steady-state absorption at 260, 213, and 183 nm was a factor of 2–4 less in KS-4V than in KU-1. The intensity of the bands at 163 nm virtually coincided in these glasses and monotonically increased with increasing EB fluence. This indicates an impact mechanism for the throughput of the oxygen-deficient centers responsible for this band.

Optics of powerful e-beam-pumped KrF-lasers

The comprehensive results are presented on the behavior of high purity synthetic CaF2, MgF2, quartz glass and Al2O3 under the action of intensive ionizing radiation (x-rays and energetic electrons) and UV laser radiation with 248-nm wavelength. They are concerned to the application of e-beam-pumped large-size KrF-laser as a driver in the Inertial Fusion Energy.

Nonlinear and electron-beam-induced absorption in pure quartz glasses at the wavelengths of excimer lasers

The two-photon absorption coefficients β at wavelengths 248 and 193nm with pulse widths 80 and 60ns, respectively, have been measured in KS-4V, KU-1, and Corning 7980 glasses. The value of β at 248nm in KS-4V was 0.16cm∕GW, which was about 30% higher than in the other glasses. At a wavelength of 193nm, the value of β virtually coincided at a level of 1.1cm∕GW in all the samples. The coupling factors between the electron-beam (EB)-induced quasi-steady-state optical density at wavelengths 353, 248, and 193nm and the EB power density on the samples were measured for the same glasses, using the radiations of XeF, KrF, and ArF lasers. These factors in KS-4V were 1, 4, and 6cm2∕GW, respectively. The measurement error did not exceed 50%.