The design of a laser oscillator with a stabilized frequency composition and a stabilized intensity of output radiation is described. The oscillator’s basic component is a TEA CO
2
module pumped by a ...self-maintained discharge and operating in a repetition-rate mode at a frequency of up to 3 Hz. A circuit for the formation of a self-maintained homogeneous discharge in the working volume of a CO
2
+ N
2
+ He mixture at atmospheric pressure is the basic component of the gas-discharge module. This circuit is based on the generation of a high-voltage pulse with a special profile, which provides high-reliability excitation of a discharge and pulse-to-pulse reproducibility of the discharge characteristics. The use of a hybrid circuit in the optical oscillator allows selection of a single longitudinal mode in the output radiation spectrum, thus eliminating undesirable interference phenomena, which lead to instability of the instantaneous values of the radiation intensity. During the development of the oscillator, the optimal operating parameters of the hybrid circuit were obtained, which ensure the high quality and reproducibility of the spatiotemporal and energy parameters of laser radiation.
A comparative study of the efficiency of the laser initiation of PETN by the first and second harmonics (1060 and 530 nm) of a neodymium-doped phosphate glass laser was performed. A significant ...difference in the efficiency of PETN initiation by the different harmonics was revealed: as the initial temperature of the sample increased from 373 to 450 K, the threshold initiation fluence decreased from 3.0 to 0.5 J/cm
2
; at the same time, the second harmonic failed to initiate PETN even at a fluence of 10 J/cm
2
. The absorption spectrum of PETN was found to have a weak absorption band with a maximum at λ
m
= 1020 nm. It was assumed that the high efficiency of initiation by the first harmonic is associated with light absorption (photo-initiation) by this band
The conductivity of KCl, KBr, NaCl, CsI crystals excited by electron pulses (50 ps, 0.2 MeV) has been investigated. The current pulse for KCl, KBr and NaCl reproduces the form of the exciting impulse ...within the resolution ability of the recording system. The decay of the current pulse for CsI is about 1 ns and is described by the second‐order kinetics. The coincidence of the current pulse decay time for CsI with the time of F‐center creation enables us to identify this duration as the lifetime of the band electrons. In this case for the band electron mobility one can obtain μ = (8 ± 2) cm2/Vs.
We designed a follow-up program to find the spectroscopic properties of the Hercules-Aquila Cloud (HAC) and test scenarios for its formation. We measured the radial velocities (RVs) of 45 RR Lyrae in ...the southern portion of the HAC using the facilities at the MDM observatory, producing the first large sample of velocities in the HAC. We found a double-peaked distribution in RVs, skewed slightly to negative velocities. We compared both the morphology of HAC projected onto the plane of the sky and the distribution of velocities in this structure outlined by RR Lyrae and other tracer populations at different distances to N-body simulations. We found that the behaviour is characteristic of an old, well-mixed accretion event with small apo-galactic radius. We cannot yet rule out other formation mechanisms for the HAC. However, if our interpretation is correct, HAC represents just a small portion of a much larger debris structure spread throughout the inner Galaxy whose distinct kinematic structure should be apparent in RV studies along many lines of sight.
The paper presents the results of measurements of the threshold (Hcr) and kinetic characteristics of the ignition of the mixed compositions based on brown coal and pentaerythritol tetranitrate when ...exposed to pulses of neodymium laser (1064 nm, 120 ms). It is shown that the threshold and kinetic characteristics are monotonically dependent on the mass ratio of coal-pentaerythritol tetranitrate.
