The aim of this work is to report the achievement of a light weight, compact, high power CO2 laser which can be used in industry. The construction and operation of a CO2 gas transport laser with cylindrical geometry and two parallel electrical discharges are presented. Using a 600 mm diameter, 1400 mm length, 250 kg laser head, we have obtained more than 1.6 kW laser power with 2% stability and 2 mrad full angle divergence. For comparison the results are presented for one electrical discharge laser. 相似文献
This paper highlights the electrical properties of two new complex tungsten bronze ceramics (K2Pb2Eu2W2Ti4Nb4O30 and K2Pb2Pr2W2Ti4Nb4O30) which were prepared by high temperature mixed oxide method. Variation of impedance parameters with temperature (27–500 °C) and frequency (1 kHz to 5 MHz) shows the grain and grain boundary effects in the samples. The variation of dielectric parameters with frequency is also studied. The ac conductivity variation with temperature clearly exhibits that the materials have thermally activated transport properties of Arrhenius type. 相似文献
Producing alloy nanoparticles by discharge‐assisted erosion of electrodes immersed in liquid nitrogen is possible in the cobalt–nickel system. Several electrode configurations are tested. When one nickel electrode faces one cobalt electrode, CoxNi1−x alloy nanoparticles are produced with nickel cubic nanoparticles and cobalt round‐shaped faceted nanoparticles. The possibility of forming alloys is attributed to a sufficiently long residence time of both parent clusters within the discharge and to their total miscibility. It is also possible to form submicrometric CoxNi1−x alloy particles when discharges between cobalt electrodes are run in liquid nitrogen loaded with nickel nanoparticles produced in a former step. Starting by discharges between Co electrodes before Ni electrodes do not produce any alloy. The two mechanisms responsible for alloy synthesis are discussed. 相似文献
Summary: Experimental results obtained by emission spectroscopy on dielectric barrier discharges (DBD) in helium/air and helium/nitrogen gas mixtures are presented. The transition between the glow mode and filamentary mode of the dielectric barrier discharge was determined, and the electrical power transferred to the discharge was calculated. Dependence of the rotational temperature versus nitrogen gas‐flow rate was investigated.
Even with a peak power of 2.1 kW and a total energy of 2.3 × 10−4 J per pulse for the FD mode (in comparison to a peak power of 270 W and 5 × 10−5 J per pulse for the GD mode) the line intensity and number of excited species are larger for the GD mode than those of the FD mode. 相似文献
The formation of vapor layers around an electrode immersed in a conducting liquid prior to generation of a plasma discharge is studied using numerical simulations. This study quantifies and explains the effects of the electrode geometry and applied voltage pulses, as well as the electrical and thermal properties of the liquids on the temporal dynamics of the pre‐breakdown conditions in the vapor layer. This model agrees well with experimental data, in particular, the time needed to reach the electrical breakdown threshold. Because the time needed for discharge ignition can be accurately predicted from the model, the parameters such as the pulse shape, voltage, and electrode configuration can be optimized under different liquid conditions, which facilitates a faster and more energy‐efficient plasma generation.
Emission spectra of microwave discharge in liquid hydrocarbons (hexane (C6H14), n‐heptane (С7Н16), decane (С10Н22), pentadecane (C15H32), cyclohexane (С6Н12), toluene (С6Н5–СН3), ortho‐xylene (С6Н5–(СН3)2), and petroleum solvent nefras S2 80/120 [mixture of light hydrocarbons with boiling temperature ranging between 33°C and 205°C]) were studied in the range of wavelength 200–700 nm. The pressure above the surface of the liquid was equal to the atmospheric pressure. It was shown that in the spectra measured in aromatic hydrocarbons (toluene and ortho‐xylene) the sequence of the Swan band with = 0 was overlapped with the molecular emission band with a maximum at 511 nm never observed before. Analysis of known data allowed us to hypothesize that this emission can be attributed to the emission of linear carbon cluster C5 . This cluster was previously observed only in absorption. Rotational temperatures determined by modeling of the sequence Δυ = −1 of the Swan band were equal to 2,000 ± 300 K for all studied hydrocarbons. 相似文献
The field-emission–related effects play a significant role in the deviation of the breakdown voltage from that predicted by Paschen's law in the range of micrometer gaps. Beginning from a certain gap spacing, breakdown voltage diverges from the climbing curve seen in the left half of the Paschen curve. In this paper, the equation governing the DC breakdown in microgaps has been solved analytically. The derived analytical relation indicates that the DC breakdown voltage in microgaps depends on the gap size d and the pressure p, particularly, rather than on the product pd. The new theoretical expression allows key features to be identified suggesting that the inclusion of the field emission at micron and submicron gaps is necessary to describe properly the experimental data. The expression presented here can receive a wider interest due to its applicability to the breakdown voltage for a series of gases, gaps and pressures and can serve as ready-to-use guidelines for system engineers and designers.https://doi.org/10.1209/0295-5075/83/25001 相似文献
