Copper Vapor Research Articles

The optimum geometrical ratio in halide lasers

Some halide lasers tubes with different volume were used to investigate the geometrical dependence of the output power of laser. An optimum length-to-bore ratio of about 30 was obtained, which gives maximum average output power of halide lasers. The relationship between maximum average output power and geometrical factors of lasers were deduced and compared by than that of copper vapour lasers. So, the straightforward relation was obtained for designing of halide lasers tubes.

Kinetics of the Active Medium of a Copper Vapor Brightness Amplifier

A spatiotemporal kinetics of the active medium of a copper vapor brightness amplifier is described that allows gain characteristics to be investigated during the pump pulse. Model calculations show that changing the discharge parameters allows the radial gain profiles to be improved significantly, as well as the gain and the inversion duration to be increased. The data obtained will be used to choose the operating conditions for the active medium in the brightness amplifier mode.

Numerical investigation of vessel heating using a copper vapor laser and a pulsed dye laser in treating vascular skin lesions

A computer simulation technique was employed to study the selective heating of a tissue vessel using emission from a pulsed copper vapor laser and a pulsed dye laser. The depth and size of vessels that could be selectively and safely removed were determined for the lasers under examination.

Temporal and Spatial Distribution of Output Power from Different Electron Temperature in Copper Vapour Laser

Temporal and Spatial Distribution of Output Power from Different Electron Temperature in Copper Vapour Laser

Hierarchical carbon-silicon nanowire heterostructures for the hydrogen evolution reaction.

Silicon nanowires (SiNWs) opened up exciting possibilities in a variety of research fields due to their unique anisotropic morphologies, facile tuning capabilities, and accessible fabrication methods. The SiNW-based photoelectrochemical (PEC) conversion has recently been known to provide an efficiency superior to that of various photo-responsive semiconductor heterostructures. However, a challenge still remains in designing optimum structures to minimize photo-oxidation and photo-corrosion of the Si surface in a liquid electrolyte. Here, we report a simple method to synthesize hierarchically branched carbon nanowires (CNWs) on SiNWs utilizing copper vapor as the catalyst in a chemical vapor deposition (CVD) process, which exhibits outstanding photocatalytic activities for hydrogen generation along with excellent chemical stability against oxidation and corrosion. Thus, we believe that the CNW-SiNW photoelectrodes would provide a new route to developing high-performing cost-effective catalysts essential for advanced energy conversion and storage technologies.

The Efficiency of the Pumping of the Lasers Based on Self-Terminating Atomic Transitions Operating in the Energy Input Cut-Off Mode

The analysis of the electro-physical processes in the discharge circuit of the lasers based on the self-terminating transitions of metal atoms (LSTM) and the electrodes placed in the cold buffer zones of the gas discharge tube (GDT) is occurred. That design of the GDT can provide the efficient lasing at the reduction of the current flowing through the switch to zero after the charging of the capacitive components of the circuit from the storage capacitor. Under the circumstances the pumping of the active medium is determined by the energy input from the peaking capacitor and, consequently, the efficiency of the pumping can be increased by an order of magnitude, if (using a managed switch) the energy input into the active medium from the storage capacitor is “cut-off” after charging the capacitive components of the circuit. It was shown that the efficiency values of ∼ 9-11 % and of ∼ 5-6 % for the copper and gold vapor, lasers could be achieved.

Synthesis of Copper Oxides Nanostructures by an Overstressed Nanosecond Discharge in Atmospheric Pressure Air between Copper Electrodes

The results of study of the characteristics and parameters of plasma of a high-current nanosecond discharge in atmospheric pressure air between copper electrodes under conditions of strong overstress of the discharge gap are presented. Under such conditions, favorable conditions are created for igniting an atmospheric pressure diffuse discharge in an inhomogeneous electric field. The spatial, electrical and optical characteristics of the discharge, as well as the parameters of the air plasma with small additions of copper vapor are studied. It is shown that this type of discharge can be used for the synthesis of copper oxides nanostructures.

Laser treatment of cutaneous angiokeratomas: A systematic review.

Angiokeratomas can present therapeutic challenges, especially in cases of extensive lesions, where traditional surgical methods carry high risks of scarring and hemorrhage. Argon, pulsed dye (PDL), neodymium-doped yttrium aluminum garnet (Nd:YAG), copper vapor, potassium titanyl phosphate, carbon dioxide, and erbium-doped yttrium aluminum garnet (Er:YAG) lasers have emerged as alternative options. To review the use and efficacy of lasers in treating angiokeratomas. A PubMed search identified randomized clinical trials, cohort studies, case series, and case reports involving laser treatment of cutaneous angiokeratomas. Twenty-five studies were included. Quality ratings were assigned using the Oxford Centre for Evidence-Based Medicine scheme. Several laser modalities are effective in treating multiple variants of angiokeratomas. Vascular lasers like PDL, Nd:YAG, and argon are the most studied and of these, PDL offers the safest side effect profile. Nd:YAG may be more effective for hyperkeratotic angiokeratomas. Combination treatment with multiple laser modalities has also demonstrated some success. Lasers are a promising treatment option for angiokeratomas, but current use is limited by the lack of treatment guidelines. There are limited high quality studies comparing laser treatments to each other and to non-laser options. Additional studies are needed to establish guidelines and to optimize laser parameters.

An apparatus for vacuum deposition of composite TiN−Cu coatings using coupled vacuum-arc and ion-plasma processes

A plasma-chemical reactor with the coupling of gas-discharge processes has been developed. These processes combine arc evaporation of titanium in a nitrogen-containing plasma and ion-plasma sputtering of copper with the formation of copper vapor. Experiments were carried out on the deposition of superhard nanostructured TiN−Cu composite layers.

Pulse-periodic HF induction-type discharge for pumping lasers on self-terminating transitions

We present the results of numerical investigation regarding the physical processes in the working medium of a copper vapour laser pumped by trains of high-frequency (ftr≈30 MHz) current oscillations with f≈10 kHz repetition rates. An electrodeless discharge achieved by employment of an induction-type process, which is new for this type of lasers, was considered. Elimination of the electrodes in the design of such inductive copper vapour laser will, in principle, provide a means to increase the lifetime and reliability of sealed discharge tubes and reduce their costs.

Development of a see-through hollow cathode discharge lamp for (Li/Ne) optogalvanic studies.

Development of a demountable and see-through hollow cathode (HC) discharge lamp suitable for optogalvanic (OG) spectroscopy is described. The design of the HC lamp is simple, compact, and inexpensive. Lithium, investigated rarely by the OG method, is selected for cathode material as its isotopes are important for nuclear industry. The HC lamp is characterized electrically and optically for discharge oscillations free OG effect. Strong OG signals of lithium as well as neon (as buffer gas) are produced precisely upon copper vapor laser pumped tunable dye laser irradiation. The HC lamp is capable of generating a clean OG resonance spectrum in the available dye laser wavelength scanning range (627.5-676 nm) obtained with 4-(Dicyanomethylene)-2-methyl-6-(4-dimethylaminostyryl)-4H-pyran dye. About 28 resonant OG lines are explicitly observed. Majority of them have been identified using j-l coupling scheme and assigned to the well-known neon transitions. One line that corresponds to wavelength near about 670.80 nm is assigned to lithium and resolved for its fine (2S1/2 → 2P1/2, 3/2) transitions. These OG transitions allow 0.33 cm-1 accuracy and can be used to supplement the OG transition data available from other sources to calibrate the wavelength of a scanning dye laser with precision at atomic levels.

Copper vapor laser pumped by pulse-periodic high-frequency discharge

We present the results of numerical experiments considering the physical processes specific to the laser based on self-terminating atomic transitions of copper and study of the output characteristics of this laser numerically. The laser is pumped by trains of high-frequency (10−70 MHz) current oscillations with the repetition rate of 2−30 kHz. Inductive-type electrodeless discharge pumping is regarded. The calculations were carried out for a small set of the specified basic parameters providing a way to partially optimize the performance of the laser over its basic output characteristics and to reveal its features. The feasibility of efficient laser pumping by high-frequency discharge is demonstrated. In our numerical experiments the maximum value of the physical efficiency was about 6% and the maximum average laser output power was as high as 174 W. These values were obtained for a discharge chamber with a volume of 1.7 L.

VENOUS ECTASIA OF THE VERMILION BORDER: COPPER VAPOR LASER TREATMENT

We present the experience of application of "Yakhroma-Med" copper vapor laser system for the treatment of venouse ectasia (VE) of the vermilion border. The yellow wavelength of the generated laser radiation reaches 578 nm falls at the peak of hemoglobin absorption. The treatment was conducted in 58 patients with VE rising above the skin for no more than 1 mm. 100% clinical result. With a hemangioma size of up to 1 cm, treatment efficiency was 87% after the first procedure and complete resolution in 13% of the patients after the second procedure. At a size of more than 1 cm, the efficiency was 71% after the first procedure and 29% after the second. A 100% clinical result was obtained. The therapeutic effect persisted throughout the year in all 58 patients. It has been established that microcirculation disorders processes and further development of VE are affected by a variety of exogenous factors: about a half (48.3%) of the patients were deliberately subjected to excessive sunlight exposure, more than a quarter lived in regions with adverse climatic factors (wind, cold, abnormally low humidity, etc.) (27.6%), or regularly received hyperthermic procedures (steam bath, sauna, etc.) (25.9%). A burn (thermal, chemical) is found in the medical history of one in every five women (20.7%). 17.2% of the patients indulged in excessive consumption of condimental, spicy and hot food.

Development of optoelectronic-based pulsed current sensor to detect the poor laser discharge condition

A current transformer (CT)-based sensor has been developed to detect poor discharge conditions in copper vapour laser. The optoelectronic-based pulsed current sensor architecture involves the optical transmitter–receiver HFBR, high-frequency current transformer, and fiber optic link. The CT has been designed and calibrated to ensure generation of an optical signal at the current threshold crossover. Bandwidth analysis of the CT is carried out using the bode plot. The optoelectronic inter-conversion of the pulsed voltage of the CT and transmission via fiber optic link provides the non-contact current sensing and remote signal processing of the signal. This study discusses the details of the sensor.

Copper-vapor-catalyzed chemical vapor deposition of graphene on dielectric substrates

Direct synthesis of high-quality graphene on dielectric substrates is important for its application in electronics. In this work, we report the process of copper-vapor-catalyzed chemical vapor deposition of high-quality and large graphene domains on various dielectric substrates. The copper vapor plays a vital role on the growth of transfer-free graphene. Both single-crystal domains that are much larger than previous reports and high-coverage graphene films can be obtained by adjusting the growth duration. The quality of the obtained graphene was verified to be comparable with that of graphene grown on Cu foil. The progress reported in this work will aid the development of the application of transfer-free graphene in the future.

Abnormally strong decrease in reflectance of molten copper due to possible generation of levitating sub-micron melt droplets

A strong decrease in reflection of a probe laser radiation at wavelength 0.66µm from the surface of molten copper in argon atmosphere is observed in laboratory experiments for the first time. Theoretical estimates based on the Mie theory indicated that this effect can be qualitatively explained by a condensation of copper vapor leading to formation of sub-micron droplets levitating above the sample. This physical model is supported by the observed diffuse scattering of incident radiation and also by a regular structure of small crystals on solid sample surface after its cooling. This structure is similar to a solidified cluster of melt droplets after the crystallization of single droplets of copper melt and subsequent growth of the crystals.

Numerical investigation of the joint impact of thermophoresis and radiative losses in induction plasma synthesis of copper nanoparticles

A numerical model for the simulation of the copper nanoparticles synthesis process by an induction thermal plasma system has been developed, taking into account the joint effects of radiative losses from the metallic vapour and thermophoretic transport of the synthetized nanoparticles on the process performance; the final aim of the work is that of setting up an accurate modelling tool for design-oriented simulation and optimization of the synthesis process. Radiative losses from copper vapour and thermophoresis have been taken into account for different reaction chamber geometries (a cylindrical one and one with a conical top section) combined with different quench gas injection strategies and different power levels, in order to evaluate the impact of these phenomena in process design strategies. The numerical results show that both these phenomena have a relevant impact on the process parameters for all the investigated cases, and that they should be taken into account in order to develop increasingly accurate models for process design and optimization.

Peering through the flames: imaging techniques for reacting aluminum powders.

Combusting metals burn at high temperatures and emit high-intensity radiation in the visible spectrum, which can oversaturate regular imaging sensors and obscure the field of view. Filtering the luminescence can result in limited information and hinder thorough combustion characterization. A method for "seeing through the flames" of a highly luminescent aluminum powder reaction is presented using copper vapor laser (CVL) illumination, synchronized with a high-speed camera. A statistical comparison of combusting aluminum particle agglomerates imaged using various filtration techniques shows the effectiveness of the high-speed camera with a CVL diagnostic approach. When ignited by an electrically induced plasma, aluminum particles are entrained as solid agglomerates that rotate about their centers of mass and are surrounded by emitted, burning gases. The average agglomerate diameter appears to be 160 μm when viewed with standard illumination and a high-speed camera. However, a significantly reduced diameter of 50 μm is recorded when imaged with CVL illumination coupled with a high-speed camera and a 511 nm notch filter. These results indicate alternative imaging techniques are required to resolve the complexities of metal particle combustion.

The use of Inductive Discharge for Laser Pumping of a Copper Vapor

Results of numerical simulation re presented for copper vapor laser (CVL) excitation by a pulse-periodical inductive discharge. A CVL realization with a coaxial discharge chamber is studied. It was shown that a coaxial chamber is better matched with specific features of inductive pumping method than an ordinary cylindrical chamber. High lasing output characteristics are obtained in numerical experiments, which confirms possibility of efficient pumping CVL by a new inductive method.

A Modified Approach for the Blumlein-line Laser Power Calculations: Electrical and Optical Power Waveforms

In this paper, a modified approach for output power calculations of the nitrogen laser system is reported. The power calculations is based on the distributed parameter model of the Blumlein-line circuit along with the decoupling approach of the laser rate equation from the electrical circuit equations. The general laser power assumption is considered in calculating the output optical power. The effect of the laser gap inductance on both the electrical and optical power waveforms is simulated and discussed. The theoretical work presented here is quite general and could be applied to many other fast discharges laser systems, such as CO2 and copper vapor lasers.