Acousto-optic (AQ) Q-switching devices with modulation loss of more than 90% at 1.06 μm wavelength have been developed for the first time. Detailed performance of the devices are described. In the Q-switch operation mode of pulsed YAG laser, output energies of 2.8 mJ to 108 mJ were obtained with pulse widths of 10 ns to 20 ns respectively.
Experiments were carried out to investigate the breakdown characteristics of SF6 gas at 3 atm between needle plane electrodes with a small gap of 1.2_??_2mm. The voltage-time characteristics of the corona and breakdown in SF6 gas were measured using μs pulse voltage of various wave fronts. Although the corona onset voltage decreased with increasing wave front, the breakdown voltage reached a maximum value as the wave front increased, and reduced at still longer wave fronts. The shape of V-t characteristics was, thus, different from that usually seen with a uniform field gap. A polarity effect was also seen on the breakdown characteristics. These anomalous breakdown characteristics are discussed together with the results of the corona properties observed with an image intensifier tube.
The plasma polymerization of paraxylene was done in a triode glow discharge system. The deposition rate increased with increasing r. f. voltage applied to the substrate electrode, its frequency, and the discharge current, and attained its maximum at 27 Pa against the monomer pressure. The deposition rate above 100 nm/min could be easily obtained by applying a r. f. voltage of 100 kHz. The temperature dependence of the capacitance and the dielectric loss tangent of the plasma-polymerized paraxylene films decreased with decreasing monomer pressure and increasing discharge current and r. f. voltage. This is due to the restriction of the dipole orientation caused by the further polymerization and higher crosslinking of the plasma-polymerized paraxylene films.
The maximum entropy method was applied to free induction decay signals of potassium solutions and mung bean root tips in order to obtain high-resolution of potassium-39 nuclear magnetic resonance spectra. Maximum entropy method provided low noise spectra with sharp peaks compared with the spectra estimated by the conventional fast Fourier transform. It was, thus, easy to observe that a linearity exists between potassium concentration and its peak area over a wide range of concentration. Potassium uptake and loss processes of mung been root tips could moreover, be traced more clearly by the maximum entropy method than from the fast Fourier transform.