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  • Articles  (27)
  • Thermal plasmas  (15)
  • Nd-YAG laser  (12)
  • 2010-2014
  • 1990-1994  (17)
  • 1985-1989  (10)
  • 1950-1954
  • Technology  (27)
  • 1
    Electronic Resource
    Electronic Resource
    Fluid boundary layer effects in atmospheric-pressure plasma diamond film deposition (1993)
    Springer
    Plasma chemistry and plasma processing 13 (1993), S. 169-187 
    Details
    ISSN: 1572-8986
    Keywords: Thermal plasmas ; chemical vapor deposition ; diamond film ; impinging jet ; atomic carbon
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Technology
    Notes: Abstract Diamond films were deposited in an atmospheric-pressure radio frequency plasma reactor. Hydrogen and methane were injected coaxially into the plasma as a high-velocity jet which impinged on the molybdenum substrate. In some cases argon was added to the reactant jet to increase its momentum, thereby reducing the boundary layer thickness. In most cases argon addition substantially, improved diamond growth. A numerical model was developed, which calculated two-dimensional reactor temperature and velocity, distributions, and the chemical kinetics in the boundary layer. The calculations indicate that under the experimental conditions argon addition reduced the thickness of the hydrogen nonequilibrium boundary layer from 3.5 to 1.0 mm. In addition, the calculations suggest that monatomic carbon may be a key diamond growth species under thermal plasma conditions.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01466040
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  • 2
    Electronic Resource
    Electronic Resource
    Spectroscopic study of a magnetically rotating arc between opper electrodes in contaminated argon (1992)
    Springer
    Plasma chemistry and plasma processing 12 (1992), S. 1-16 
    Details
    ISSN: 1572-8986
    Keywords: Thermal plasmas ; electrode erosion ; plasma spectroscopy ; metal vapor plasma ; electrode contamination
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Technology
    Notes: Abstract The effects of N2 and CO contaminants in atmospheric-pressure argon on an arc rotating between two concentric copper electrodes has been studied using optical spectroscopy of copper lines. The axial temperature of the magnetically driven arc in Ar + %N2 was determined to be around 10,000 K for arc currents of SO to 200 A. The diffusion process of the copper vapor from the cathode was also studied. A copper density maximum 1 mm from the cathode along the arc column was found in Ar + %N2. Removal of the contaminated cathode surface layers by the arc when contaminant injection in the plasma gas was stopped was found to be a slow process with a time scale depending on the type of the gas contaminant. The presence of gas contaminant in the electrode material controls the cathode erosion mechanism and the overall arc behavior in the transition between a contaminated to a pure argon arc.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01447941
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  • 3
    Electronic Resource
    Electronic Resource
    Computational fluid dynamics modeling of multicomponent thermal plasmas (1992)
    Springer
    Plasma chemistry and plasma processing 12 (1992), S. 299-325 
    Details
    ISSN: 1572-8986
    Keywords: Thermal plasmas ; plasma processing ; rnulticomponent ; chemistry ; diffusion
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Technology
    Notes: Abstract A comprehensive computational model has been developed Jbr flowing thermal plasmas in the absence of electromagnetic fields, with particular emphasis on plasma jets. The plasma is represented as a rnulticomponent chemicalh, reacting ideal gas with temperature-dependent thermodynamic and transport properties. The plasma flow is governed by the transient compressible Navier-Stokes equations in two or three space dimensions. Turbulence is represented by subgrid-scale and k-ε models. Species diffusion is calculated by an effective binary diffusion approximation, generalized to allow /or ambipolar diffusion of charged species. Ionization, dissociation, recombination, and other chemical reactions are computed by general kinetic and equilibrium chemistry algorithms. Radiation heat loss is currently modeled as a temperature-dependent energy sink. Finite-difference approximations to the governing equations are solved on a rectangular spatial mesh using explicit temporal differencing. Computational inefficiency at low Mach number is avoided br reducing the effective sound speed. The overall computational model is embodied in a new computer code called LAVA. Computational results and comparisons with experimental data are presented Jbr LAVA simulations of a steady-stare axisymmetric argon plasma jet flowing into cold argon.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01447028
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  • 4
    Electronic Resource
    Electronic Resource
    Nd-YAG laser ablation of arteriosclerotic obstructions: Clinical long-term results in femoropopliteal artery occlusions (1991)
    Springer
    Lasers in medical science 6 (1991), S. 311-315 
    Details
    ISSN: 1435-604X
    Keywords: Arteriosclerotic obstructions ; Laser recanalization ; Nd-YAG laser
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine , Physics , Technology
    Notes: Abstract Laser recanalization of peripheral artery occlusions was performed in 338 patients. A continuous wave Nd-YAG laser was used in combination with ‘sapphire-probe’ laser catheters. The initial recanalization rate was 85%. Complications such as dissections, perforations, emboli and spasm were observed in 14%. The cumulative patency rate after 3 years was 48%.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02030886
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  • 5
    Electronic Resource
    Electronic Resource
    A thermal appraisal of the ablation process in canine aorta in vivo using a 100 μm pulsed Nd-YAG laser (1991)
    Springer
    Lasers in medical science 6 (1991), S. 373-378 
    Details
    ISSN: 1435-604X
    Keywords: Heat necrosis ; Modelling ; Nd-YAG laser ; Dog aorta
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine , Physics , Technology
    Notes: Abstract A model has been developed to calculate distal tissue necrosis in vascular tissue after application of a 100μ laser pulse from a Nd-YAG laser (5 kW peak pulse power on a 0.13 mm2 spot size). The model assumes that the temperature profile in the tissue is proportional to the laser light fluence rate and that the distal tissue necrosis depth is that depth in the tissue where there is a temperature increase of 42 °C minus the etch rate (ablation depth per laser pulse). The fluence rate has been calculated using the diffusion approximation to the radiative transport equation. The tissue optical parameters (absorption and reduced scattering coefficients) have been derived from published data. The etch rate used (10μm per pulse) is derived from in vivo experimental results. The model predicts a damage depth varying between 0 and 2.33 mm (mean 1.10 mm) and this is compared with an experimental result (0.77 mm) in dog aorta.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02042459
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  • 6
    Electronic Resource
    Electronic Resource
    Heat transfer from a transferred-arc plasma to a cylindrical enclosure (1991)
    Springer
    Plasma chemistry and plasma processing 11 (1991), S. 57-79 
    Details
    ISSN: 1572-8986
    Keywords: Thermal plasmas ; transferred arc ; plasma reactor ; radiated power ; heat transfer to enclosure ; voltage gradient ; electric field
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Technology
    Notes: Abstract Hear-transfer rates from an axially enclosed transferred arc to a surrounding water-cooled cylindrical sleeve, 15 cm high, were measured. The arc (argon or nitrogen) was struck between a movable cathode within the sleeve and a bath of molten copper below the sleeve, serving as anode. The distance from the bottom of the sleeve to the surface of the molten copper (L o) was constant. Variables studied were the diameterD of the sleeve (5, 7.5. and 10 cm), the length of the arc within the sleeveL (5, 10, and 15 cm), the currentI (200, 250, and 300 A) and a tangential flow of gas or vortex within the sleeve (0, ?0, and 50 liters/min). The total power transferred to the sleeve,P s was measured caloronetrically and was the sure ofP r the effective power radiated by the arc of lengthL within the sleeve.P a, the power radiated into the sleeve from the arc of length Lo below the sleeve, andP o , the power radiated from the melt surface (a constant of small value), minusP a , the power lost by convection from the sleeve (negligible, except for a strong vortex). BothP r andP o were found to be equal to the product of the Joule heat released within their respective arc lengths, IVgL and IVg0L0 (where Vg and Vg0 are the voltage gradients), and dimenonless efliciency factors, ηr and η0. which are functions ofL/D andL 0 /D, respectively, for each gas, regardless of the geometry of the sleeve, the current, and the strength of the vortex.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01447034
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  • 7
    Electronic Resource
    Electronic Resource
    The use of Nd-YAG laser in the treatment of malignant tumours of the oral and maxillofacial regions (1991)
    Springer
    Lasers in medical science 6 (1991), S. 209-212 
    Details
    ISSN: 1435-604X
    Keywords: Nd-YAG laser ; Tumour ; Oral and maxillofacial region
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine , Physics , Technology
    Notes: Abstract Thirty cases with malignant neoplasms of the oral and maxillofacial regions treated by Nd-YAG laser are presented. All of them have been followed-up for 2–4 years, and the results are satisfactory. In 26 cases, the tumours disappeared clinically, were negative in pathological examination, and no recurrence was found in the 2–4 year follow-up period.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02032551
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  • 8
    Electronic Resource
    Electronic Resource
    Contact Nd-YAG laser in mastectomy and axillary evacuation: a prospective randomized study (1991)
    Springer
    Lasers in medical science 6 (1991), S. 205-208 
    Details
    ISSN: 1435-604X
    Keywords: Nd-YAG laser ; Breast cancer ; Axillary evacuation ; Operation ; Nd-YAG contact technique
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine , Physics , Technology
    Notes: Abstract Thirty patients underwent modified mastectomy for breast cancer. They were allocated into three operation groups. Group A (n=10) underwent conventional operation, group B (n=10) contact Nd-YAG laser operation, and group C (n=10) conventional mastectomy with laser evacuation of the axillary lymph nodes. The operation with contact Nd-YAG laser was slower (p〈0.05) than the conventional operation. Laser significantly reduced pre-operative bleeding (p〈0.01), but there were post-operative wound seromas in 50% of the cases. No other complications occurred. It is concluded that contact Nd-YAG laser is safe and reduces bleeding by sealing small vessels. However, there seems to be a risk for post-operative wound seromas particularly after radical axillary lymph node dissection.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02032550
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  • 9
    Electronic Resource
    Electronic Resource
    The histological measurement of laser-induced thermal damage in vascular tissue using the stain picrosirius red F3BA (1991)
    Springer
    Lasers in medical science 6 (1991), S. 399-405 
    Details
    ISSN: 1435-604X
    Keywords: Laser vascular anastomoses ; Argon ion laser ; Laser recanalization ; Nd-YAG laser ; Sapphire probe
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine , Physics , Technology
    Notes: Abstract A histological technique for the measurement of laser-induced thermal tissue damage is described using the stain picrosirius red F3BA. This stain enhances the birefringence of normal collagen when viewed in polarized light. Areas of (thermally) denatured collagen, however, have no optical activity and can be measured directly by optical micrometry. The technique has been applied to experimental studies on both laser angioplasty and laser vascular anastomosis. The tissue ablation characteristics of various 2.2 mm diameter rounded sapphire laser angioplasty probes were compared by lasing (at 1064 nm) segments of porcine aorta under blood in vitro. A marked difference was observed between probes from different manufacturers, the Surgical Laser Technologies probe producing significantly greater forward tissue ablation with less associated lateral thermal damage. The relative degree of thermal damage caused by argon (488/514 nm) and Nd-YAG lasers during in vitro arteriotomy repair was also investigated. No difference was seen between the two wavelengths. However, the use of absorption-enhancing chromophore dyes as an aid to laser welding significantly reduced damage, particularly for the argon laser. In conclusion, we suggest that this histological technique is of considerable value in the investigation of the thermal effects of continuous-wave lasers.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02042462
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  • 10
    Electronic Resource
    Electronic Resource
    Palliative treatment for oesophagogastric cancer by laser photocoagulation (1990)
    Springer
    Lasers in medical science 5 (1990), S. 217-221 
    Details
    ISSN: 1435-604X
    Keywords: Oesophageal cancer ; Nd-YAG laser ; Endoscopic treatment
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine , Physics , Technology
    Notes: Abstract Over a 10 year period, 149 non-surgical patients were treated for palliation of an oesophageal cancer. One hundred and twenty-nine patients had an advanced cancer; 20 had a small cancer. The initial success rate was 81% and the complications rate was 3.1% for advanced cancers. Average duration of improvement after initial improvement was 138 days. Location was the only factor affecting the initial results in advanced cancers. Improvement duration was affected by the reason for treatment and an association of treatments during follow up. A complete local destruction of the small cancers was obtained in 18 patients. Three patients had a local recurrence during follow up.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02031386
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  • 11
    Electronic Resource
    Electronic Resource
    Tumour ablation by laser in general surgery (1990)
    Springer
    Lasers in medical science 5 (1990), S. 185-193 
    Details
    ISSN: 1435-604X
    Keywords: Breast ; Lung ; Liver ; Rectum ; Anal tumour ablation ; Nd-YAG laser ; CO2 laser
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine , Physics , Technology
    Notes: Conclusions More surgeons are becoming interested in laser surgery, but, in laser tumour ablation the real improvement in open surgery can only be provided by: 1. The use of the right parameters and lasers in every discipline. The recent outcome of combined CO2 and Nd-YAG delivery in the same beam (Combolaser, Lasermatic OY), and the velocity to obtain a suitable blend of the two energies, in relation with the nature of the irradiated tissues, will give to the surgeon new opportunities in laser surgery. 2. Significant results in the reduction of local recurrences, using a reproducible technique of wound sterilization by laser hyperthermia. Multicentre studies should be undertaken to answer this important question. 3. A better and earlier detection of small or microtumours with new imaging techniques, allowing for a total destruction by immunophototherapy and/or new photosensitizers, progresses in which intra-abdominal or intra-thoracic applications may found a new deal.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02031380
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  • 12
    Electronic Resource
    Electronic Resource
    Neurosurgical lasers for tumour removal (1990)
    Springer
    Lasers in medical science 5 (1990), S. 241-244 
    Details
    ISSN: 1435-604X
    Keywords: CO2 laser ; Nd-YAG laser ; Endoscopic laser ; Stereotaxic laser surgery ; Intracranial tumours ; Intraorbital tumours ; Intraspinal tumours
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine , Physics , Technology
    Notes: Abstract The early 1970s saw the birth of microscopic neurosurgery and the late 1970s the birth of laser neurosurgery. For more than 10 years now, laser radiations have been used during neurosurgical procedures: mostly for tumoral removal concerning essentially benign lesions. The reference laser has been and still is the CO2 laser, which has a limited penetration into CNS tissues. Until recently the Nd-YAG laser was used with its normal spectral transition, 1.064 μm. Because of its important diffusion in the CNS, it cannot be widely used except for shrinking large vascularized tumours such as meningiomas. The technological evolution has brought the laser specialists—physicists, medical doctors and surgeons—new concepts and new wavelengths which will progressively broaden laser applications and surgical procedures towards greater effectiveness, security and simplification. Holmium-YAG (2.1 μm), Erbium-YAG (2.9 μm) or long Nd-YAG wavelengths (1.44 or 1.32 μm) have been studied by different teams. The 1.32 μm Nd-YAG transition has been clinically used for about 2 years by a few neurosurgical teams (Beck in Munich, Roux in Paris, and more recently Lombard and Fasano in Torino, Ascher in Gratz). Laser radiations can be useful essentially during the removal of benign tumours, mostly if they are well vascularized and placed near functional structures such as the brain stem, the cranial nerves, the spinal cord: the CO2 laser is most efficient for vaporization; 1.06 Nd-YAG is effective for coagulation; 1.32 Nd-YAG provides very satisfactory photoevaporation effects if used with a superpulsed emission, and/or with a focusing handpiece, it also has good haemostatic properties with a c.w. output. The development of new optic fibre conducted wavelengths appears to be a possible answer to new requisites which should lead to the development of endoscopic neurosurgery (intraventricular tumours, discal herniations) and sterotaxic laser surgery (deep-seated intra-cerebral lesions).
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02031390
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  • 13
    Electronic Resource
    Electronic Resource
    Technique of laser lesser-curve seromyotomy (1990)
    Springer
    Lasers in medical science 5 (1990), S. 323-325 
    Details
    ISSN: 1435-604X
    Keywords: Nd-YAG laser ; Sapphire tips ; Stomach seromyotomy ; Chronic duodenal ulcers
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine , Physics , Technology
    Notes: Abstract A new technique for performing a lesser-curve superficial myotomy of the stomach for the treatment of chronic duodenal ulceration has been proposed, using Nd-YAG laser energy delivered to the target via sapphire tips. A total of 12 patients have been operated on with only one haemorrhagic complication.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02032662
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  • 14
    Electronic Resource
    Electronic Resource
    Hydrodynamics and heat transfer in a plasma spouted bed reactor (1990)
    Springer
    Plasma chemistry and plasma processing 10 (1990), S. 71-85 
    Details
    ISSN: 1572-8986
    Keywords: Thermal plasmas ; spouted bed ; hydrodynamics ; heat transfer
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Technology
    Notes: Abstract The literature reveals very little intformation about plasma spouted bed hydrodynamics. Spouting of corindon particles with diameters ranging from 0.4 to 3.36 mm with argon plasma was conducted in a 90-mm-diameter column in the temperature range 300–1300°C. It was found that the maximum spoutable height (Hm) decreases with increasing particle diameter and decreasing mean bed temperature. A relation between the inlet plasma velocity and Hm is proposed. Concerning heat transport phenomena in the annulus, measurements and calculations indicate a large axial diffusivity but a poor radial mixing. Typical values of Dz and Dr are proposed on the basis of an identification procedure.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01460448
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  • 15
    Electronic Resource
    Electronic Resource
    One-dimensional analysis of the wall region for a multiple-temperature argon plasma (1990)
    Springer
    Plasma chemistry and plasma processing 10 (1990), S. 189-206 
    Details
    ISSN: 1572-8986
    Keywords: Thermal plasmas ; modeling ; heat and mass transfer
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Technology
    Notes: Abstract The present analysis is restricted to the wall region for a confined gas plasma and applied specifically to an argon plasma. The wall may be either positive or negative in potential with respect to the plasma, and the electric current may flow either parallel or normal to the wall. Estimates of the Debye shielding distance and the mean free path of various components are made to obtain the range of validity of the analysis, in addition to the situation where the wall acts like a cathode, an anode, or an electrical insulation. Analysis is for a one-dimensional case with an outer boundary, where the plasma temperature is specified. The computational domain is split into a continuum region, where both equilibrium compositions for a two-temperature plasma and a chemically reacting plasma are studied, and a free-fall region. The results allow a quantitative assessment of temperature nonequilibrium and electrical potential distribution in the free-fall region.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01460455
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  • 16
    Electronic Resource
    Electronic Resource
    Lasers in rectosigmoid tumours (1990)
    Springer
    Lasers in medical science 5 (1990), S. 223-232 
    Details
    ISSN: 1435-604X
    Keywords: Rectosigmoid cancer ; Rectosigmoid villous adenoma ; Argon laser ; Nd-YAG laser ; Endoscopic treatment
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine , Physics , Technology
    Notes: Abstract The argon and the Nd-YAG lasers were used in the Lille Multidisciplinary Laser Centre for endoscopic destruction of rectosigmoid tumours over a 10 year period in 530 patients. The goal of the treatment was palliation of a rectal cancer (200 patients), palliation of a rectal polyposis after total colectomy (17 patients) and cure of a benign rectosigmoid villous adenoma (313 patients). The initial success and complications rates were, respectively, 88 and 2.7% for rectal cancers, 92 and 2% for villous adenomas and 100 and 0% for rectal polyposis. Average duration of improvement was 10.1 months for advanced rectosigmoid cancers. During a 3.1 years average follow up, the recurrence rate was 14% in patients with a villous adenoma. Immediate results were affected by the reason for treatment, the initial symptoms and the circumferential extension of the tumour base in advanced cancers and only by the circumferential extension in villous adenomas. Long-term results were affected by the reason for treatment and the circumferential extension in advanced cancers and the reason for treatment, initial histology and location in villous adenomas.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02031388
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  • 17
    Electronic Resource
    Electronic Resource
    Lesser curve photoseromyolysis with the Nd-YAG laser (1990)
    Springer
    Lasers in medical science 5 (1990), S. 317-322 
    Details
    ISSN: 1435-604X
    Keywords: Nd-YAG laser ; Lesser curve photoseromyolysis ; Duodenal ulcer ; Non endoscopic method
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine , Physics , Technology
    Notes: Abstract We confirmed in animal experiments that the Nd-YAG laser can be used to replace conventional surgical techniques for duodenal ulcer disease—lesser curve seromyotomy, as proposed by Taylor. The experiments suggest that the operative time may be halved using the laser. We confirmed that the ideal laser parameters for this technique were: wavelength 1319nm and power output 15 W, using a contact sapphire tip, with repeated pulses of 0.25 s. Histological studies were performed to show the effect of the laser on the stomach wall and on the vagus nerve. It was shown that the pH was elevated from 1.3 to 6.9 or even higher. The first successful operation on man with this technique was performed in May 1989.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02032661
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  • 18
    Electronic Resource
    Electronic Resource
    Open lung surgery with Nd-YAG Laser (1989)
    Springer
    Lasers in medical science 4 (1989), S. 13-16 
    Details
    ISSN: 1435-604X
    Keywords: Nd-YAG laser ; Open lung surgery
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine , Physics , Technology
    Notes: Abstract We report on nineteen patients who successfully underwent open lung performance with a Nd-YAG laser in the period December 1987 to August 1988. Reasons for laser operations were lung metastases (twelve cases), lung fibrosis (five patients), one lung cyst and one tuberculoma. We used the Nd-YAG laser in non-contact mode, with focus hand-piece spot size of 1.5 mm, a continual 1064 nm wavelength and a power output 90 W. In these nineteen cases we performed 35 laser photoablations of lung tissue. All patients healed without any serious complications. The major advantage of Nd-YAG laser beam in open lung surgery is in the rapid sealing effect of small airways and of blood vessels up to 3 mm. The Nd-YAG laser seems to be very suitable for operations in lung periphery.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02032504
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  • 19
    Electronic Resource
    Electronic Resource
    Thermal plasma composition in the presence of easily and noneasily ionized components (1989)
    Springer
    Plasma chemistry and plasma processing 9 (1989), S. 445-463 
    Details
    ISSN: 1572-8986
    Keywords: Thermal plasmas ; equilibrium composition ; metal halide discharge ; easily and noneasily ionized components
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Technology
    Notes: Abstract The influence of easily and noneasily ionized components on equilibrium particle density ratios in thermal plasmas has been investigated. Particular emphasis is given to the modeling of metal halide discharges with iodine as a halide. The calculations were done for “standard” air with lithium or iodine, “standard” argon with aluminum, and with a mixture of aluminum and iodine. The system setup is in agreement with spectroscopic results for an open-chamber gas-stabilized d.c. arc, with a pressure of 1×105 Pa and temperatures corresponding to the radial distribution of temperature for this type of discharge. It is shown that the behavior of the plasma core is dominated by the easily ionized component (Li or Al) while the periphery is characterized by the noneasily ionized component (iodine).
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01023913
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  • 20
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    Electronic Resource
    Nonequilibrium effects in thermal plasma chemistry (1989)
    Springer
    Plasma chemistry and plasma processing 9 (1989), S. 435-443 
    Details
    ISSN: 1572-8986
    Keywords: Thermal plasmas ; nonequilibrium ; finite rates ; dissociation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Technology
    Notes: Abstract Numerical calculations have been performed to assess the potential significance of nonequilibrium effects on chemical reactivity in thermal plasmas The calculations consider situations in which the electron temperature and/or the electron density are elevated above their equilibrium values corresponding to the local gas temperature. Such nonequilibrium may occur in the plasma torch itself or could be purposefully imposed by a controlled hybrid discharge in a downstream reactor region so as to augment reactivity over a longer residence time. The calculations account for finite ionization/recombination rates of atomic and molecular species, electron-impact dissociation, dissociative recombination, dissociative attachment, and predissociation effects, as well as thermal reactions between neutral chemical species. As an example of the possible nonequilibrium enhancement of molecular decomposition, initial consideration has focused on the dissociation rates of diatomic species where heavy particle reaction rates and cross sections can be reasonably estimated. The results show that for O2 or H2 in argon at moderate temperatures, electron-temperature elevation can give rise to a notable enhancement of the dissociation rate, in comparison with the equilibrium case. Depending on the situation, it is found that either relatively energetic electron-impact dissociation or dissociative attachment (for O2) can dominate the enhanced dissociation rate—which can be more than a factor of 2 greater than in the absence of a discharge. Similar effects would be expected for the decomposition of more complicated molecules.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01023912
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  • 21
    Electronic Resource
    Electronic Resource
    Some characteristics of transferred-Arc plasmas (1989)
    Springer
    Plasma chemistry and plasma processing 9 (1989), S. 65S 
    Details
    ISSN: 1572-8986
    Keywords: Thermal plasmas ; transferred arcs ; plasma radiation ; plasma heat transfer ; plasma columns ; plasma stability
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Technology
    Notes: Abstract Although the theoretical foundations of the characteristics of transferred arcs were established more than three decades ago, the design of reator systems based on this method of plasma are generation is still in an early stage of development. Although deceptively simple in concept, attempts to use transferred arcs im practical applications at scales of arc length and power somewhat larger than those previously studied in the laboratory soon revealed that considerably more information was required on the arc's unique properties before a sound reactor design could be carried out. This was principally due to the much higher temperature levels (up to 20,000 K) with consequent much higher radiative power achieved in this type of arc, as well as the fluid mechanical effects of the high-velocity plasma gas flowing in the latter. These, in turn, had profound effects on the various modes of heat transfer occurring in the system, on the stability of the arc, on the injection of the material to be treated, and on the overall efficiency of energy utilization in the whole system. The objective of this paper is to summarize the experimental evidence concerning transforred arc characteristics which have been obtained by the author and his colleageus during recent years.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01015874
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  • 22
    Electronic Resource
    Electronic Resource
    Particle behavior in thermal plasmas (1989)
    Springer
    Plasma chemistry and plasma processing 9 (1989), S. 167S 
    Details
    ISSN: 1572-8986
    Keywords: Thermal plasmas ; heat, mass, and momentum transfer ; material processing ; overview
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Technology
    Notes: Abstract In this overview, effects exerted on the motion and on heat and mass transfer of particulates injected into a thermal plasma are discussed, including an assessment of their relative importance in the context of thermal plasma processing of materials. Results of computer experiments are shown for particle sizes ranging from 5–50 μm, and for alumina and tungsten as sample materials. The results indicate that (i) the correction terms required for the viscous drag and the convective heat transfer due to strongly varying properties are the most important factors; (ii) noncontinuum effects are important for particle sizes 〈10 μm at atmospheric pressure, and these effects will be enhanced for smaller particles and/or reduced pressures; (iii) the Basset history term is negligible, unless relatively large and light particles are considered over long processing distances; (iv) thermophoresis is not crucial for the injection of particles into thermal plasmas; (v) turbulent dispersion becomes important for particle 〈10 μm in diameter; and (vi) vaporization describes a different particle heating history than that of the evaporation process which, however, is not a critical control mechanism for interphase mass transfer of particles injected into thermal plasmas.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01015878
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  • 23
    Electronic Resource
    Electronic Resource
    Silicon nitride synthesis in an atmospheric pressure convection—Stabilized arc (1989)
    Springer
    Plasma chemistry and plasma processing 9 (1989), S. 277-289 
    Details
    ISSN: 1572-8986
    Keywords: Thermal plasmas ; synthesis of Si3N4 ; experiments
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Technology
    Notes: Abstract Submicron α-, β-, and amorphous-phase silicon nitride particles have been synthesized in an experimental plasma reactor, using metallic silicon and ammonia as reactants. Injection of ammonia at different locations of the reactor results in different yields. A maximum yield of 85 wt% has been achieved by injecting NH3 at both downstream and upstream locations of the reactor. The powders synthesized in this way contained approximately 60 wt% silicon nitride in crystal form with equal amounts of α and β phases. The remainder consisted of the amorphous phase. The average size of the particles ranged from 50 to 90 nm, with a standard deviation of 1.47–1.87 depending on the location of ammonia injection. Seeding with 1 and 10 wt% of preexisting silicon nitride particles for fostering heterogeneous nucleation did not improve the yield, but it changed the particle size distribution.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01054286
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  • 24
    Electronic Resource
    Electronic Resource
    Modelling particle formation and growth in a plasma synthesis reactor (1988)
    Springer
    Plasma chemistry and plasma processing 8 (1988), S. 145-157 
    Details
    ISSN: 1572-8986
    Keywords: Thermal plasmas ; particle nucleation and growth ; modelling
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Technology
    Notes: Abstract A model for particle nucleation and growth in a thermal plasma reactor is discussed. A nondimensional form of the aerosol general dynamic equation is derived under a set of simplifying assumptions which are appropriate to plasma powder synthesis, and the resulting set of equations is solved numerically. The results are converted to dimensional form for the case of iron powder, for which experimental data are available, and for silicon carbide. Calculated particle sizes increase significantly with increasing reactant concentrations and with decreasing cooling rate, although the influence of cooling rate is mainly a residence time effect.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01016154
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  • 25
    Electronic Resource
    Electronic Resource
    Particle dynamics and particle heat and mass transfer in thermal plasmas. Part I. The motion of a single particle without thermal effects (1985)
    Springer
    Plasma chemistry and plasma processing 5 (1985), S. 211-237 
    Details
    ISSN: 1572-8986
    Keywords: Thermal plasmas ; particle motion ; computer experiments ; review
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Technology
    Notes: Abstract A particle injected into a thermal plasma will experience a number of effects which are not present in an ordinary gas. In this paper effects exerted on the motion of a particle will be reviewed and analyzed in the context of thermal plasma processing of materials. The primary purpose of this paper is an assessment of the relative importance of various effects on particle motion. Computer experiments are described, simulating motion of a spherical particle in a laminar, confined plasma jet or in a turbulent, free plasma jet. Particle sizes range from 5 to 50 µm, and as sample materials alumina and tungsten are considered. The results indicate that (i) the correction term required for the viscous drag coefficient due to strongly varying properties is the most important factor; (ii) non-continuum effects are important for particle sizes 〈10 µm at atmospheric pressure and these effects will be enhanced for smaller particles and/or reduced pressures; (iii) the Basset history term is negligible, unless relatively large and light particles are considered over long processing distances; (iv) thermophoresis is not crucial for the injection of particles into thermal plasmas; (v) turbulent dispersion becomes important for particle 〈10 µm in diameter.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00615122
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  • 26
    Electronic Resource
    Electronic Resource
    Particle dynamics and particle heat and mass transfer in thermal plasmas. Part II. Particle heat and mass transfer in thermal plasmas (1985)
    Springer
    Plasma chemistry and plasma processing 5 (1985), S. 391-414 
    Details
    ISSN: 1572-8986
    Keywords: Thermal plasmas ; heat and mass transfer ; review
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Technology
    Notes: Abstract This paper is concerned with a review of heat and mass transfer between thermal plasmas and particulate matter. In this situation various effects which are not present in ordinary heat and mass transfer have to be considered, including unsteady conditions, modified convective heat transfer due to strongly varying plasma properties, radiation, internal conduction, particle shape, vaporization and evaporation, noncontinuum conditions, and particle charging. The results indicate that (i) convective heat transfer coefficients have to be modified due to strongly varying plasma properties; (ii) vaporization, defined as a mass transfer process corresponding to particle surface temperatures below the boiling point, describes a different particle heating history than that of the evaporation process which, however, is not a critical control mechanism for interphase mass transfer of particles injected into thermal plasmas; (iii) particle heat transfer under noncontinuum conditions is governed by individual contributions from the species in the plasma (electrons, ions, neutral species) and by particle charging effects.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00566011
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  • 27
    Electronic Resource
    Electronic Resource
    Generation and behavior of fine particles in thermal plasmas—A review (1985)
    Springer
    Plasma chemistry and plasma processing 5 (1985), S. 1-37 
    Details
    ISSN: 1572-8986
    Keywords: Thermal plasmas ; fine particles ; review
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Technology
    Notes: Abstract The generation and processing of fine powders in thermal plasmas has attracted increasing interest over the past years, precipitated by a growing awareness that conservation of materials is no longer an option but rather a necessity. Plasmaspheroidization, densification, fuming, metallurgical reduction, and the production of refractory oxides, carbides, nitrides, and borides in thermal plasmas are fast developing technologies which, in some cases, have already reached industrial production scale. In this survey, pertinent literature (198 references) will be reviewed with emphasis on basic studies in this field, reported over the past 20 years. The first part of this review covers powder handling, quenching characteristics, nucleation and growth, and modeling of plasma-particle interactions. The second part is concerned with plasma furnaces for the production of fine particles, including RF induction plasmas, DC anode furnaces, DC plasma jets, DC transferred arcs, cathode pump fed arcs, hybrid induction-DC plasmas, and three-phase AC furnaces.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00567907
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