Characterization of the excimers of poly(N-vinylcarbazole) using TRANES

International Nuclear Information System (INIS)

Ghosh, Debanjana; Chattopadhyay, Nitin

2011-01-01

Time-resolved emission spectra (TRES) and time-resolved area normalized emission spectra (TRANES) are exploited to characterize the excimers of poly(N-vinylcarbazole) (PNVC) in toluene and water. The time-resolved study together with the steady state measurements, decipher the fluorescence of the system containing pendant carbazole moieties in the polymer backbone unambiguously. Isoemissive point in the TRANES establishes that there are only two excimers of PNVC, the partially overlapped excimer emitting at high energy and the sandwich type excimer emitting at lower energy, and they are formed exclusively in the photoexcited state. The study substantiates an equilibrium between the two excimers. - Graphical Abstract: Highlights: → TRES and TRANES are exploited to decipher the emission of PNVC in toluene and water. → The emission comes from two excimers: partially overlapped and sandwich type. → TRANES shows single isoemissive point establishing presence of two excimers only. → Sandwich excimer is formed from the partially overlapped one in the excited state. → Existence of an equilibrium is established.

Time Evolution of the Excimer State of a Conjugated Polymer Laser

Directory of Open Access Journals (Sweden)

Wafa Musa Mujamammi

2017-11-01

Full Text Available An excited dimer is an important complex formed in nano- or pico-second time scales in many photophysics and photochemistry applications. The spectral and temporal profile of the excimer state of a laser from a new conjugated polymer, namely, poly (9,9-dioctylfluorenyl-2,7-diyl (PFO, under several concentrations in benzene were investigated. These solutions were optically pumped by intense pulsed third-harmonic Nd:YAG laser (355-nm to obtain the amplified spontaneous emission (ASE spectra of a monomer and an excimer with bandwidths of 6 and 7 nm, respectively. The monomer and excimer ASEs were dependent on the PFO concentration, pump power, and temperature. Employing a sophisticated picosecond spectrometer, the time evolution of the excimer state of this polymer, which is over 400 ps, can be monitored.

Electrodeless excimer laser; Laser a eccimeri senza elettrodi

Energy Technology Data Exchange (ETDEWEB)

Lisi, N. [ENEA, Divisione Nuovi Materiali, Centro Ricerche Casaccia, Rome (Italy)

2001-07-01

In this paper it is proposed how to build an excimer laser based on an electrodeless discharge (or Dielectric Barrier Discharge). Such laser could operate with a low energy per pulse (<100 mJ) and a high repetition rate (<100 kHz). The most relevant advantage an electrodeless DBD laser is the much longer gas mixture lifetime. This feature could allow the operation of a sealed laser emitting higher average power with respect to commercially available excimer lasers. Such discharge scheme could be advantageous in order to excite the F{sub 2} excimer molecule, whose emission wavelength in the VUV range (157 nm) at high reprate is particularly interesting in the micro-lithography field. [Italian] In questo documento viene proposto come costruire un laser a eccimeri basato su una scarica priva di elettrodi, o Dielectric Barrier Discharge. Tale laser puo' funzionare con una bassa energia per impulso (<100 mJ) ad alta frequenza di ripetizione (<100 kHz). Il vantaggio fondamentale di un laser a DBD e quindi privo di elettrodi e' la vita media della miscela gassosa molto piu' alta che potrebbe permettere alla camera laser di operare sigillata ad una potenza media superiore a quella dei laser a eccimeri attuali. Tale schema di pompaggio potrebbe essere particolarmente vantaggioso per eccitare la molecola eccimero F{sub 2} la cui lunghezza di emissione nel VUV (157 nm) ad elevata frequenza di ripetizione presenta un notevole interesse nel campo della produzione di microcircuiti.

Myopic keratomileusis by excimer laser on a lathe.

Science.gov (United States)

Ganem, S; Aron-Rosa, D; Gross, M; Rosolen, S

1994-01-01

We designed an excimer laser keratomileusis delivery system to increase the regularity of the refractive cut surface and allow greater precision in the level and shape of the ablated zone. A parallel faced corneal disc was produced by microkeratectomy from six human eyes and surgical keratectomy in 12 beagle corneas. A 193-nanometer excimer laser that was used to project an oval beam onto the corneal disc was rotated on a flat surface to ensure overlapping of the ovally ablated areas between pulses. Electron microscopy of eye bank lenticules demonstrated a circular smooth regularly concave ablation zone. Histological examination of nine clear corneas confirmed thinning of the stroma without fibroblastic reaction and no epithelial hypertrophy. Mean preoperative corneal power of 43.15 +/- 2.18 decreased postoperatively to 33.61 +/- 2.34. The new technique of excimer laser keratomileusis has the advantage of a cut surface smoother and the clear zone is devoid of the stepwise concavity and irregularity seen in diaphragm based photoablation delivery systems.

Excimer-mediated photoionization of covalently-linked diaryl compounds: Energy thresholds for excimer formation and excimer-assisted photoionization of jet-cooled bis (9-Fluorenyl) methane

International Nuclear Information System (INIS)

Lee, Jae Kwang; Kang, Heun Kag; Cho, Han Joung; Boo, Bong Hyun; Lim, Edward C.

2001-01-01

Diarylakanes capable of adopting a face-to face arrangement of the two aromatic rings are ideal systems in which to probe the excited-state dynamics leading to excimer formation and the role of the singlet excimer in the photoionization of covalently linked bichromophoric molecules. Bis (9-eluorenyl) methane, BFM, is a good example of such diaryl compounds. Boo and co-workers have shown that BFM exhibits excrimer fluorescence in solution at ambient temperatures. An Arrhenius plot of the temperature-dependent excimer formation rate yielded activation energy of about 15 kJ·mol -1 . It has been proposed that the activation energy is related to the barrier for transforming the initial S 1 geometry to the face-to face (sandwich-pair) geometry of the intramolecular singlet excimer. This is accord with the study of an intramolecular excimer formation in jet-cooled 1, 3-diphenylpropane (DPP), and that of an intramolecular exciplex formation in 1-(9-anthryl)-3-(4-N, N-dimethylaniline) propane, which indicate that the energy threshold for such conformational changes is about 11 kJ·mol -1 .

Excimer laser: a module of the alopecia areata common protocol.

Science.gov (United States)

McMichael, Amy J

2013-12-01

Alopecia areata (AA) is an autoimmune condition characterized by T cell-mediated attack of the hair follicle. The inciting antigenic stimulus is unknown. A dense perbulbar lymphocytic infiltrate and reproducible immunologic abnormalities are hallmark features of the condition. The cellular infiltrate primarily consists of activated T lymphocytes and antigen-presenting Langerhans cells. The xenon chloride excimer laser emits its total energy at the wavelength of 308 nm and therefore is regarded as a "super-narrowband" UVB light source. Excimer laser treatment is highly effective in psoriasis, another T cell-mediated disorder that shares many immunologic features with AA. The excimer laser is superior in inducing T cell apoptosis in vitro compared with narrowband UVB, with paralleled improved clinical efficacy. The excimer laser has been used successfully in patients with AA. In this context, evaluation of the potential benefit of 308-nm excimer laser therapy in the treatment of AA is clinically warranted. Herein, the use of a common treatment protocol with a specifically designed module to study the outcome of excimer laser treatment on moderate-to-severe scalp AA in adults is described.

Excimer laser corneal surgery and free oxygen radicals.

Science.gov (United States)

Bilgihan, K; Bilgihan, A; Akata, F; Hasanreisoğlu, B; Türközkan, N

1996-01-01

Corneal photoablation with 193 nm argon fluoride excimer laser is a new technique for the treatment of refractive errors and for removing corneal opacities and irregularities. Ultraviolet radiation and thermal injury induce free radical formation in the tissues. The aim of this study was to confirm the production of free radicals by excimer laser photoablation in rabbits. The thermal changes of the posterior corneal surface were recorded during excimer laser photoablation. The lipid peroxide (LPO) levels and superoxide dismutase (SOD) activities of aqueous humour were measured after excimer laser keratectomy. The aqueous LPO levels were not changed after excimer laser ablation, but both the thermal increase in the cornea during the photoablation and the decreased aqueous SOD activities suggest that free radicals are formed in the cornea during excimer laser keratectomy, and that they may be responsible for some of the complications of excimer laser corneal surgery.

The argon excimer laser

International Nuclear Information System (INIS)

Wrobel, W.G.

1981-02-01

The electron-beam-pumped argon eximer laser is investigated and tuned for the first time. The electron beam is generated by means of an improved coaxial field emmision diode in which argon gas is excited with power densities of 0.3 GW/cm 3 for 18 ns. The processes in the excited gas of 20 to 65 bar are described in the context of a kinetic model as a sequence of stationary states. Investigations of the amplified spontaneous emission (superfluorescence) confirm the predictions of this model. Only the absorption due to the excited Ar atoms is anomalously high. Reproducible operation of the argon eximer laser was achieved in a wide pressure range with various resonator arrangements. The wavelength of this shortest wavelength of this shortest wavelength excimer laser is 126 nm, the laser line width approx. 1.7 nm, the pulse length 7 to 13 ns, and the laser power 250 kW. The laser emission is tuned from 123.2 nm to 128.4 nm by two different methods (diffraction grating and prism). This tunable laser is thus the one with the shortest wavelength at present. Its line width is 0.25 to 0.4 nm, and the power ue 1.7 kW. (orig.)

Automatic alignment of double optical paths in excimer laser amplifier

Science.gov (United States)

Wang, Dahui; Zhao, Xueqing; Hua, Hengqi; Zhang, Yongsheng; Hu, Yun; Yi, Aiping; Zhao, Jun

2013-05-01

A kind of beam automatic alignment method used for double paths amplification in the electron pumped excimer laser system is demonstrated. In this way, the beams from the amplifiers can be transferred along the designated direction and accordingly irradiate on the target with high stabilization and accuracy. However, owing to nonexistence of natural alignment references in excimer laser amplifiers, two cross-hairs structure is used to align the beams. Here, one crosshair put into the input beam is regarded as the near-field reference while the other put into output beam is regarded as the far-field reference. The two cross-hairs are transmitted onto Charge Coupled Devices (CCD) by image-relaying structures separately. The errors between intersection points of two cross-talk images and centroid coordinates of actual beam are recorded automatically and sent to closed loop feedback control mechanism. Negative feedback keeps running until preset accuracy is reached. On the basis of above-mentioned design, the alignment optical path is built and the software is compiled, whereafter the experiment of double paths automatic alignment in electron pumped excimer laser amplifier is carried through. Meanwhile, the related influencing factors and the alignment precision are analyzed. Experimental results indicate that the alignment system can achieve the aiming direction of automatic aligning beams in short time. The analysis shows that the accuracy of alignment system is 0.63μrad and the beam maximum restoration error is 13.75μm. Furthermore, the bigger distance between the two cross-hairs, the higher precision of the system is. Therefore, the automatic alignment system has been used in angular multiplexing excimer Main Oscillation Power Amplification (MOPA) system and can satisfy the requirement of beam alignment precision on the whole.

Low temperature high-mobility InZnO thin-film transistors fabricated by excimer laser annealing

NARCIS (Netherlands)

Fujii, M.; Ishikawa, Y.; Ishihara, R.; Van der Cingel, J.; Mofrad, M.R.T.; Horita, M.; Uraoka, Y.

2013-01-01

In this study, we successfully achieved a relatively high field-effect mobility of 37.7?cm2/Vs in an InZnO thin-film transistor (TFT) fabricated by excimer layer annealing (ELA). The ELA process allowed us to fabricate such a high-performance InZnO TFT at the substrate temperature less than 50?°C

Agglomeration of amorphous silicon film with high energy density excimer laser irradiation

International Nuclear Information System (INIS)

He Ming; Ishihara, Ryoichi; Metselaar, Wim; Beenakker, Kees

2007-01-01

In this paper, agglomeration phenomena of amorphous Si (α-Si) films due to high energy density excimer laser irradiation are systematically investigated. The agglomeration, which creates holes or breaks the continuous Si film up into spherical beads, is a type of serious damage. Therefore, it determines an upper energy limit for excimer laser crystallization. It is speculated that the agglomeration is caused by the boiling of molten Si. During this process, outbursts of heterogeneously nucleated vapor bubbles are promoted by the poor wetting property of molten silicon on the SiO 2 layer underneath. The onset of the agglomeration is defined by extrapolating the hole density as a function of the energy density of the laser pulse. A SiO 2 capping layer (CL) is introduced on top of the α-Si film to investigate its influence on the agglomeration. It is found that effects of the CL depend on its thickness. The CL with a thickness less than 300 nm can be used to suppress the agglomeration. A thin CL acts as a confining layer and puts a constraint on bubble burst, and hence suppresses the agglomeration

308nm Excimer Laser in Dermatology

Science.gov (United States)

Mehraban, Shadi

2014-01-01

308nm xenon-chloride excimer laser, a novel mode of phototherapy, is an ultraviolet B radiation system consisting of a noble gas and halide. The aim of this systematic review was to investigate the literature and summarize all the experiments, clinical trials and case reports on 308-nm excimer laser in dermatological disorders. 308-nm excimer laser has currently a verified efficacy in treating skin conditions such as vitiligo, psoriasis, atopic dermatitis, alopecia areata, allergic rhinitis, folliculitis, granuloma annulare, lichen planus, mycosis fungoides, palmoplantar pustulosis, pityriasis alba, CD30+ lympho proliferative disorder, leukoderma, prurigo nodularis, localized scleroderma and genital lichen sclerosus. Although the 308-nm excimer laser appears to act as a promising treatment modality in dermatology, further large-scale studies should be undertaken in order to fully affirm its safety profile considering the potential risk, however minimal, of malignancy, it may impose. PMID:25606333

Matrix metalloproteinase expression in excimer laser wounded rabbit corneas

Science.gov (United States)

Hahn, Taewon; Chamon, Wallace; Akova, Yonja; Stark, Walter J.; Stetler-Stevenson, William G.; Azar, Dimitri T.

1994-06-01

This study was performed to obtain information about matrix metalloproteinase (MMP) expression in excimer-wounded corneas and to determine whether MMPs expression correlates with the depth of the ablation. 6-mm excimer keratectomy (60 or 180 micrometers ) was performed using the 193-mm ArF excimer laser on 12 NZW rabbits. Corneas treated with mechanical epithelial debridement and untreated corneas served as controls. Rabbits were killed at 20 and 30 hr after laser ablation. Zymography after SDS extraction was performed on regenerated central epithelium and the central stroma to determine MMPs expression. We observed enzymatic activity of a 92 KDa band in the epithelium of excimer-ablated corneas but not in that following debridement wounds and untreated controls. The expression of the 92 KDa MMP was most pronounced with the deeper excimer ablation. A 72 KDa band of enzymatic activity present in the stroma of all treated and control eyes was also seen in the epithelium of excimer-ablated corneas. These proteolytic enzymes may play an important role in wound healing and remodelling after excimer keratectomy.

Advances in 193 nm excimer lasers for mass spectrometry applications

Science.gov (United States)

Delmdahl, Ralph; Esser, Hans-Gerd; Bonati, Guido

2016-03-01

Ongoing progress in mass analysis applications such as laser ablation inductively coupled mass spectrometry of solid samples and ultraviolet photoionization mediated sequencing of peptides and proteins is to a large extent driven by ultrashort wavelength excimer lasers at 193 nm. This paper will introduce the latest improvements achieved in the development of compact high repetition rate excimer lasers and elaborate on the impact on mass spectrometry instrumentation. Various performance and lifetime measurements obtained in a long-term endurance test over the course of 18 months will be shown and discussed in view of the laser source requirements of different mass spectrometry tasks. These sampling type applications are served by excimer lasers delivering pulsed 193 nm output of several mJ as well as fast repetition rates which are already approaching one Kilohertz. In order to open up the pathway from the laboratory to broader market industrial use, sufficient component lifetimes and long-term stable performance behavior have to be ensured. The obtained long-term results which will be presented are based on diverse 193 nm excimer laser tube improvements aiming at e.g. optimizing the gas flow dynamics and have extended the operational life the laser tube for the first time over several billion pulses even under high duty-cycle conditions.

Configuration of organic dye excimers in nanoporous SiO2 matrices

International Nuclear Information System (INIS)

Sorokin, A.V.; Gnap, B.A.; Bespalova, I.I.; Yefimova, S.L.; Malyukin, Yu.V.

2016-01-01

The effect of cyanine dye 3,3′-dioctadecyloxacarbocyanine perchlorate (DiO) and benzimidazole dye 4-dimethylamino-1,8-naphthoylene-1′,2′-benzimidazole (DNBI) accumulation in nanoporous silica matrices on the dyes luminescence properties has been studied. For both dyes, ground state dimer formation with perpendicular transition dipoles at high dye concentrations has been considered as a result of restricted geometry of the nanoscale pores. The dimer excitation leads to excimer formation revealing by appearance of new long-wavelength luminescence band and shortening the dye luminescence lifetime. In the excimer luminescence excitation spectra two additional bands have been observed, one of which is bathochromically shifted relatively to the absorption band and another one is hypsocromically shifted. Using the Kasha exciton model it was shown that the excimers possess oblique transition dipoles configuration. - Highlights: • Organic dye molecules are efficiently accumulated in nanoporous silica matrices. • Restricted geometry of SiO 2 nanopores provokes excimerization of both cyanine and benzimidazole dyes. • The excimers reveal configuration of oblique dimers. • The excimers are originated from ground state dimers with a perpendicular arrangement of transition dipoles.

Modification of BSCCO surface by excimer laser annealing

International Nuclear Information System (INIS)

Ibi, A.; Akitsu, T.; Matsuzawa, H.

2002-01-01

Irradiation of Kr-F excimer laser onto the BSCCO calcined pellets changed their surface to be amorphous. SEM micrographs showed that sintering of the irradiated pellets recrystallized the surface layer and much reduced the intergrain gaps as compared with only sintered pellets, whereas the internal structure of the irradiated pellets remained unchanged. This processing made the surface-layer grains be tightly connected, resulting in the higher critical temperature than the conventionally sintered samples. We can say that excimer laser annealing process is a novel scheme to reduce the surface weak-link of the high Tc superconductors. (author)

High Efficiency Mask Based Laser Materials Processing with TEA-CO2 - and Excimer Laser

DEFF Research Database (Denmark)

Bastue, Jens; Olsen, Flemmming Ove

1997-01-01

In general, mask based laser materials processing techniques suffer from a very low energy efficiency. We have developed a simple device called an energy enhancer, which is capable of increasing the energy efficiency of typical mask based laser materials processing systems. A short review of the ...... line marking with TEA-CO2 laser of high speed canning lines. The second one is manufactured for marking or microdrilling with excimer laser....

Recent advances in excimer laser technology at Los Alamos

International Nuclear Information System (INIS)

Bigio, I.J.; Czuchlewski, S.; McCown, A.W.; Taylor, A.J.

1991-01-01

This paper reports that current research in excimer laser technology at Los Alamos progresses in two major areas: In the Bright Source program, the development of ultra-high brightness (sub-piosecond) laser systems, based on discharge -pumped excimer laser amplifiers, continues Recently the authors have completed rigorous measurements of the saturation parameter for ultra-short pulses. In the laser fusion program, implementation of the large KrF laser fusion amplifiers have been accompanied by numerous studies of the laser physics and kinetics of large e-beam pumped devices

Investigation on gas medium parameters for an ArF excimer laser through orthogonal experimental design

Science.gov (United States)

Song, Xingliang; Sha, Pengfei; Fan, Yuanyuan; Jiang, R.; Zhao, Jiangshan; Zhou, Yi; Yang, Junhong; Xiong, Guangliang; Wang, Yu

2018-02-01

Due to complex kinetics of formation and loss mechanisms, such as ion-ion recombination reaction, neutral species harpoon reaction, excited state quenching and photon absorption, as well as their interactions, the performance behavior of different laser gas medium parameters for excimer laser varies greatly. Therefore, the effects of gas composition and total gas pressure on excimer laser performance attract continual research studies. In this work, orthogonal experimental design (OED) is used to investigate quantitative and qualitative correlations between output laser energy characteristics and gas medium parameters for an ArF excimer laser with plano-plano optical resonator operation. Optimized output laser energy with good pulse to pulse stability can be obtained effectively by proper selection of the gas medium parameters, which makes the most of the ArF excimer laser device. Simple and efficient method for gas medium optimization is proposed and demonstrated experimentally, which provides a global and systematic solution. By detailed statistical analysis, the significance sequence of relevant parameter factors and the optimized composition for gas medium parameters are obtained. Compared with conventional route of varying single gas parameter factor sequentially, this paper presents a more comprehensive way of considering multivariables simultaneously, which seems promising in striking an appropriate balance among various complicated parameters for power scaling study of an excimer laser.

Excimer lasers utilizing XeF and XeCl molecules

Energy Technology Data Exchange (ETDEWEB)

Bychkov, Yu I; Konovalov, I N; Losev, V F; Mesyats, G A; Ryzhov, V V; Tarasenko, V F; Fedorov, A I; Shemyakina, S B; Yastremskii, A G

1978-12-01

The results are given of an experimental and theoretical study of XeF (wavelength approx. 350 nm) and XeCl (wavelength approx. 308 nm) lasers excited by an electron beam, a discharge stabilized by an electron beam, and a rapid discharge. These lasers are representative of ones employing halides of noble gases, which are the most powerful sources of stimulated emission in the uv region. The XeCl laser is shown to have good emission characteristics with various methods of excitation. An analysis of the kinetics of processes in the plasma of lasers utilizing halides of noble gases showed that the main channel for the transfer of the beam's energy to the formation of excimer molecules is the ionic channel. An efficiency of about 2.6 percent and a specific radiant energy of 10 J.l/sup -1/ showed that XeCl* is one of the most effective excimer molecules.

Plastic scintillators based on polymers with eliminated excimer forming

Energy Technology Data Exchange (ETDEWEB)

Adadurov, A.F., E-mail: adadurov@isma.kharkov.u [Institute for Scintillating Materials NAN of Ukraine, 60 Lenin Ave, 61001 Kharkov (Ukraine); Yelyseev, D.A.; Titskaya, V.D.; Lebedev, V.N.; Zhmurin, P.N. [Institute for Scintillating Materials NAN of Ukraine, 60 Lenin Ave, 61001 Kharkov (Ukraine)

2011-05-15

Plastic scintillators (PS) were made based on benzyl methacrylate and methyl-methacrylate P(BzMA + MMA) copolymer in which the excimer forming rate is by two order lesser than that in polystyrene-based polymer matrix. Studying of these PS light yield demonstrates the importance of migration processes comparing to excimer formation. It is found that to obtain PS with high scintillation efficiency it is necessary to use the polymer base (matrix) in which excimer forming is eliminated but the migration process along the chromophores is maximally favored. To explain the accelerated energy transfer between phenyl chromophores it is proposed to use a mechanism of exchange of that virtual excitons that can propagate along a one-dimensional back-bone of polymer molecule. Clearing the details of mechanism of interaction between chromophores of polymer molecules which is responsible for accelerated radiationless energy transfer enable will determine in future the way of effective plastic scintillators designing.

Excimer PRK testing in the clinic

Science.gov (United States)

Forrest, Gary T.

1994-06-01

Testing of the excimer lasers used in PRK requires special considerations in terms of ease of use, day-to-day reliability, and high resolution to see details of beam interference effects. SensorPhysics employs a patented photochromic material on a polyester substrate to record permanent, instant records of the laser and laser system output. Since each SensorCard is used only once concerns about detection device deterioration are not an issue. The SensorCards have a demonstrated resolving power on the order of 0.1 micrometers . A small, portable reading device is used to convert the SensorCard optical density to a mJ/cm2 value. Special software also measures beam uniformity to +/- 1% to provide both qualitative and quantitative analysis. Results of use in clinic environments will be presented. In particular detection of exposure `islands' will be demonstrated. The techniques employed are similar to those we developed for UV laser micromachining and lithography four years ago.

Laser spectroscopy of the products of photoevaporation with a short-wavelength (λ = 193 nm) excimer laser

International Nuclear Information System (INIS)

Gochelashvili, K S; Zemskov, M E; Evdokimova, O N; Mikhkel'soo, V T; Prokhorov, A M

1999-01-01

An excimer laser spectrometer was designed and constructed. It consists of a high-vacuum interaction chamber, a short-wavelength (λ = 193 nm) excimer ArF laser used for evaporation, a probe dye laser pumped by an XeCl excimer laser, and a system for recording a laser-induced fluorescence signal. This spectrometer was used to investigate nonthermal mechanisms of photoevaporation of a number of wide-gap dielectrics. (laser applications and other topics in quantum electronics)

XeCl excimer laser with new prism resonator configurations and its performance characteristics

Energy Technology Data Exchange (ETDEWEB)

Benerji, N. S., E-mail: nsb@rrcat.gov.in, E-mail: bsingh@rrcat.gov.in; Singh, A.; Varshnay, N.; Singh, Bijendra, E-mail: nsb@rrcat.gov.in, E-mail: bsingh@rrcat.gov.in [Excimer Laser Section, LMPD, Raja Ramanna Center for Advanced Technology, Indore 452013 (India)

2015-07-15

New resonator cavity configurations, namely, the prism resonator and unstable prism resonator, are demonstrated for the first time in an excimer (XeCl) laser with interesting and novel results. High misalignment tolerance ∼50 mrad is achieved with considerably reduced beam divergence of less than ∼1 mrad without reduction in output power capabilities of the laser. The misalignment tolerance of ∼50 mrad is a dramatic improvement of ∼25 times compared to ∼2 mrad normally observed in standard excimer laser with plane-plane cavity. Increase in depth of focus from 3 mm to 5.5 mm was also achieved in case of prism resonator configuration with an improvement of about 60%. Unstable prism resonator configuration is demonstrated here in this paper with further reduction in beam divergence to about 0.5 mrad using plano-convex lens as output coupler. The misalignment tolerance in case of unstable prism resonator was retained at about 30 mrad which is a high value compared to standard unstable resonators. The output beam spot was completely filled with flat-top profile with prism resonator configurations, which is desired for various material processing applications. Focusing properties and beam divergence in case of prism resonator have been investigated using SEM (scanning electron microscope) images. SEM images of the focused spot size (∼20 μm holes) on metal sheet indicate beam divergence of about 0.05 mrad which is about 1.5 times diffraction limit. Energy contained in this angle is thus sufficient for micro-machining applications. Clean and sharp edges of the micro-holes show high pointing stability with multiple shot exposures. Such characteristics of the excimer laser system will be extremely useful in micro-machining and other field applications.

Excimer Laser Curing Of Polymer Coatings

Science.gov (United States)

Klick, David; Akerman, M. Alfred; Paul, George L.; Supurovic, Darko; Tsuda, Haruki

1988-12-01

The use of the excimer laser as a source of energy for photo-assisted curing of industrial polymeric coatings was investigated. Presently, UV lamps are sometimes used to excite a photoinitiating molecule mixed with the starting monomers and oligomers of a coating. The resulting polymeric chain reaction multiplies the effect of the initial photons, making economical use of the light source. The high cost of laser photons may thus be justifiable if lasers provide advantages over lamps. A series of visibly transparent 7 μm coatings (a typical thickness for 'slick' magazine coatings) with various photoinitiators, monomers, and oligomers was illuminated with excimer laser light of various wavelengths, fluences, and pulse repetition rates. For the optimum parameters, it was found that the laser had large advantages in curing speed over existing UV lamp processes, due to its monochromaticity. Pigmented coatings (20 μm TiO2 mixtures typical of appliance or automotive finishes) are not easily cured with UV lamps due to the inability of light to penetrate the absorbing and scattering pigmented layer. However, economically-viable cure rates were achieved with certain photoinitiators using a tunable excimer-pumped dye laser. A prototype of such a laser suitable for factory use was built and used to cure these coatings. Results are scaled to a factory situation, and costs are calculated to show the advantages of the laser method over currently used processes.

Excimer Formation Dynamics of Dipyrenyldecane in Structurally Different Ionic Liquids.

Science.gov (United States)

Yadav, Anita; Pandey, Siddharth

2017-12-07

Ionic liquids, being composed of ions alone, may offer alternative pathways for molecular aggregation. These pathways could be controlled by the chemical structure of the cation and the anion of the ionic liquids. Intramolecular excimer formation dynamics of a bifluorophoric probe, 1,3-bis(1-pyrenyl)decane [1Py(10)1Py], where the fluorophoric pyrene moieties are separated by a long decyl chain, is investigated in seven different ionic liquids in 10-90 °C temperature range. The long alkyl separator allows for ample interaction with the solubilizing milieu prior to the formation of the excimer. The ionic liquids are composed of two sets, one having four ionic liquids of 1-butyl-3-methylimidazolium cation ([bmim + ]) with different anions and the other having four ionic liquids of bis(trifluoromethylsulfonyl)imide anion ([Tf 2 N - ]) with different cations. The excimer-to-monomer emission intensity ratio (I E /I M ) is found to increase with increasing temperature in sigmoidal fashion. Chemical structure of the ionic liquid controls the excimer formation efficiency, as I E /I M values within ionic liquids with the same viscosities are found to be significantly different. The excited-state intensity decay kinetics of 1Py(10)1Py in ionic liquids do not adhere to a simplistic Birk's scheme, where only one excimer conformer forms after excitation. The apparent rate constants of excimer formation (k a ) in highly viscous ionic liquids are an order of magnitude lower than those reported in organic solvents. In general, the higher the viscosity of the ionic liquid, the more sensitive is the k a to the temperature with higher activation energy, E a . The trend in E a is found to be similar to that for activation energy of the viscous flow (E a,η ). Stokes-Einstein relationship is not followed in [bmim + ] ionic liquids; however, with the exception of [choline][Tf 2 N], it is found to be followed in [Tf 2 N - ] ionic liquids suggesting the cyclization dynamics of 1Py(10)1Py

The effect of excimer laser keratectomy on corneal glutathione-related enzymes in rabbits.

Science.gov (United States)

Bilgihan, Ayşe; Bilgihan, Kamil; Yis, Ozgür; Yis, Nilgün Safak; Hasanreisoglu, Berati

2003-04-01

Glutathione related enzymes are involved in the metabolism and detoxification of cytotoxic and carcinogenic compounds as well as reactive oxygen species. Excimer laser is a very useful tool for the treatment of refractive errors and removing superficial corneal opacities. Previous studies have shown that excimer laser may initiate free radical formation in the cornea. In the present study, we evaluated the effect of excimer laser keratectomy on corneal glutathione-related enzyme activities in rabbits. Animals were divided into five groups, and all groups were compared with the controls (group 1), after epithelial scraping (group 2), transepithelial photorefractive keratectomy (PRK) (group 3), traditional PRK (group 4) and deep traditional PRK (group 5). Corneal glutathione peroxidase (GPx), glutathione S-transferase (GST) and glutathione reductase (GR) activities were measured after 24h. Corneal GPx and GR activities significantly decreased only in group 5 (p < 0.05) but GST activities significantly decreased in all groups when compared with the control group (p < 0.05). In conclusion, excimer laser inhibits the glutathione dependent defense system in the cornea, this effect becomes more prominent after high doses of excimer laser energy and antioxidants may be useful to reduce free radical mediated complications.

Simulation of pulsed dielectric barrier discharge xenon excimer lamp

International Nuclear Information System (INIS)

Bogdanov, E A; Kudryavtsev, A A; Arslanbekov, R R; Kolobov, V I

2004-01-01

Recently, it has been shown that the efficiency of excimer lamps can be drastically increased in a pulsed regime. A one-dimensional simulation of pulsed excimer lamps has been performed by Carman and Mildren (2003 J. Phys. D: Appl. Phys. 36 19) (C and M). However, some computational results of the work of C and M are questionable and need to be revisited. In this paper, a dielectric barrier discharge (DBD) in xenon has been simulated for operating conditions similar to those of C and M to better understand plasma dynamics in a pulsed regime. Our simulation results differ considerably from the computational results of C and M. Although these differences do not affect profoundly the plasma macro parameters measured in the C and M experiments, they offer a better understanding of plasma dynamics in pulsed DBDs and form a solid foundation for computational optimization of excimer lamps. It was found that the dynamics of breakdown and the current pulse depend significantly on the initial densities of species after a previous pulse, and so it is important to accurately simulate the plasma evolution in both the afterglow and active stages. It seems possible to modify the power deposition in the plasma by varying external discharge parameters such as the amplitude and the rise time of the applied voltage, and to modify the plasma composition by changing the pulse repetition rate and plasma decay in the afterglow stage

[Glycosaminoglycans in subepithelial opacity after excimer laser keratectomy].

Science.gov (United States)

Nakayasu, K; Gotoh, T; Ishikawa, T; Kanai, A

1996-05-01

We evaluated histochemically the characteristics of glycosaminoglycans and proteoglycans in the corneal subepithelial opacity after excimer laser keratectomy on rabbit corneas. We also performed the same evaluations on the cornea after mechanical keratectomy. Twenty days after the operations, the area immediately subjacent to the epithelium showed strong staining with toluidine blue, alcian blue, and colloidal iron. However, after treatment with chondroitinase ABC or chondroitinase AC, alcian blue staining in this area decreased dramatically. Antilarge proteoglycan antibody also reacted strongly in this area. Histochemical and immunohistochemical examination of the cornea where mechanical keratectomy was done showed basically similar findings with the cornea of excimer laser keratectomy. These results suggest that large-molecula proteoglycans with chondroitine sulfate side chains become localized in the subepithelial area after two different kinds of keratectomies. We presume from histochemical and immunohistochemical observations that the subepithelial opacity observed after excimer laser keratectomy is not a special reaction to excimer laser but simply a corneal scar formed after stromal resection.

Treatment of oral lichen planus using 308-nm excimer laser.

Science.gov (United States)

Liu, Wei-Bing; Sun, Li-Wei; Yang, Hua; Wang, Yan-Fei

2017-09-01

Oral lichen planus (OLP) is a chronic inflammatory disease, has prolonged courses, repeated attacks and resistance to treatment. The traditional narrow spectrum UVB treatment has an established efficacy on skin lichen planus, and high safety. However, most of ultraviolet phototherapy devices have a huge volume, thereby cannot be used in the treatment of OLP. Lymphocytic infiltration is evident in the lesions of lichen planus, and the direct irradiation of 308-nm excimer laser can induce apoptosis of the T lymphocytes in skin lesions, thereby has a unique therapeutic effect on the diseases involving T lymphocytes. This study aims to investigate the efficacy of 308-nm excimer laser in the treatment of OLP. A total of six OLP patients were enrolled into this study, and further pathological diagnosis was conducted, then 308-nm excimer laser was used in the treatment. The efficacy of 308-nm excimer laser in the treatment of OLP was satisfactory. The clinical symptoms of five patients were significantly improved. In two patients, the erosion surface based on congestion and the surrounding white spots completely disappeared, and clinical recovery was achieved. Three patients achieved partial remission, that is, the erosion surface healed, congestion and white spot area shrunk by more than 1/2 of the primary skin lesions. In the remaining one patient, the erosion surface had not completely healed after treatment, and congestion and white spot area shrunk by less than 1/2 of the primary skin lesions. Only one patients had developed mild pain during the treatment, and this symptom alleviated by itself. The 308-nm excimer laser therapy can serve as a safe and effective treatment for OLP. © 2017 Wiley Periodicals, Inc.

308-nm excimer laser in endodontics

Science.gov (United States)

Liesenhoff, Tim

1992-06-01

Root canal preparation was performed on 20 extracted human teeth. After opening the coronal pulp, the root canals were prepared by 308 nm excimer laser only. All root canals were investigated under SEM after separation in the axial direction. By sagittal separation of the mandibles of freshly slaughtered cows, it was possible to get access to the tissues and irradiate under optical control. Under irradiation of excimer laser light, tissue starts to fluoresce. It was possible to demonstrate that each tissue (dentin, enamel, bone, pulpal, and connective tissue) has a characteristic spectral pattern. The SEM analyses showed that it is well possible to prepare root canals safely. All organic soft tissue has been removed by excimer laser irradiation. There was no case of via falsa. The simultaneous spectroscopic identification of the irradiated tissue provides a safe protection from overinstrumentation. First clinical trials on 20 patients suffering of chronical apical parodontitis have been carried out successfully.

Excimer laser beam delivery systems for medical applications

Science.gov (United States)

Kubo, Uichi; Hashishin, Yuichi; Okada, Kazuyuki; Tanaka, Hiroyuki

1993-05-01

We have been doing the basic experiments of UV laser beams and biotissue interaction with both KrF and XeCl lasers. However, the conventional optical fiber can not be available for power UV beams. So we have been investigating about UV power beam delivery systems. These experiments carry on with the same elements doped quartz fibers and the hollow tube. The doped elements are OH ion, chlorine and fluorine. In our latest work, we have tried ArF excimer laser and biotissue interactions, and the beam delivery experiments. From our experimental results, we found that the ArF laser beam has high incision ability for hard biotissue. For example, in the case of the cow's bone incision, the incision depth by ArF laser was ca.15 times of KrF laser. Therefore, ArF laser would be expected to harden biotissue therapy as non-thermal method. However, its beam delivery is difficult to work in this time. We will develop ArF laser beam delivery systems.

The Excimer Laser: Its Impact on Science and Industry

Science.gov (United States)

Basting, Dirk

2010-03-01

After the laser was demonstrated in 1960, 15 years were required to develop a practical method for extending laser emission into the UV: the Excimer laser. This historical review will describe the challenges with the new medium and provide an insight into the technological achievements. In the transition from Science to Industry it will be shown how start-ups successfully commercialized laboratory prototypes. The pioneers in this rapidly expanding field will be identified and the influence of government-funded research as well as the role of venture capital will be discussed. In scientific applications, the fields of photochemistry and material research were particularly stimulated by the advent of a reliable UV light source. Numerous industrial applications and worldwide research in novel applications were fueled In the early and mid 80's by progress in excimer laser performance and technology. The discovery of ablative photocomposition of polymer materials by Srinivasan at IBM opened the door to a multitude of important excimer applications. Micromachining with extreme precision with an excimer laser enabled the success of the inkjet printer business. Biological materials such as the human cornea can also be ``machined'' at 193nm, as proposed in 1983 by Trokel and Srinivasan. This provided the foundation of a new medical technology and an industry relying on the excimer laser to perform refractive surgery to correct vision Today, by far the largest use of the excimer laser is in photolithography to manufacture semiconductor chips, an application discovered by Jain at IBM in the early 80's. Moore's law of shrinking the size of the structure to multiply the number of transistors on a chip could not have held true for so long without the deep UV excimer laser as a light source. The presentation will conclude with comments on the most recent applications and latest market trends.

KrF excimer laser precision machining of hard and brittle ceramic biomaterials

International Nuclear Information System (INIS)

Huang, Yao-Xiong; Lu, Jian-Yi; Huang, Jin-Xia

2014-01-01

KrF excimer laser precision machining of porous hard–brittle ceramic biomaterials was studied to find a suitable way of machining the materials into various desired shapes and sizes without distorting their intrinsic structure and porosity. Calcium phosphate glass ceramics (CPGs) and hydroxyapatite (HA) were chosen for the study. It was found that KrF excimer laser can cut both CPGs and HA with high efficiency and precision. The ablation rates of CPGs and HA are respectively 0.081 µm/(pulse ⋅ J cm −2 ) and 0.048 µm/(pulse ⋅ J cm −2 ), while their threshold fluences are individually 0.72 and 1.5 J cm −2 . The cutting quality (smoothness of the cut surface) is a function of laser repetition rate and cutting speed. The higher the repetition rate and lower the cutting speed, the better the cutting quality. A comparison between the cross sections of CPGs and HA cut using the excimer laser and using a conventional diamond cutting blade indicates that those cut by the excimer laser could retain their intrinsic porosity and geometry without distortion. In contrast, those cut by conventional machining had distorted geometry and most of their surface porosities were lost. Therefore, when cutting hard–brittle ceramic biomaterials to prepare scaffold and implant or when sectioning them for porosity evaluation, it is better to choose KrF excimer laser machining. (paper)

Phenylethynylpyrene excimer forming hybridization probes for fluorescence SNP detection

DEFF Research Database (Denmark)

Prokhorenko, Igor A.; Astakhova, Irina V.; Momynaliev, Kuvat T.

2009-01-01

Excimer formation is a unique feature of some fluorescent dyes (e.g., pyrene) which can be used for probing the proximity of biomolecules. Pyrene excimer fluorescence has previously been used for homogeneous detection of single nucleotide polymorphism (SNP) on DNA. 1-Phenylethynylpyrene (1-1-PEPy...

Laser drilling of metals with a XeCl excimer laser

NARCIS (Netherlands)

Schoonderbeek, A.

2005-01-01

This thesis is about laser drilling with a unique excimer laser with a nearly diffraction-limited beam and relatively long optical pulse duration of 175 ns. The combination of high processing speed and high processing quality suitable for industrial applications can be obtained because the excellent

Prototype of an excimer laser for microprocessing

Science.gov (United States)

Iwanejko, Leszek; Pokora, Ludwik J.; Wolinski, Wieslaw L.

1991-08-01

The paper presents a brief description of a prototype of a XeC1 excimer laser for micraprocessing of materials. The planned main parameters of the laserare as follows: wavelength . . . . . . . . . . . . . . . . . . . . . . . . . 308 nm -''energyofapulse. . . . . . . . . . . . . lOOmJ -pulseduration (FWHM) . . . . . . . . . . . . . . . 2Ons repetition frequency . . . . . . . . . . . . . . 1O Hz peak power of a pulse . . . . . . . . . . . . . . . 5 MW With respect to currently carrried works with the prototype we show only preliminary results of testing of a laser head. The obtained maximum laser pulse energy exceeded 90 ml. However it should be pointed out that this value was obtained without any opt i mi z at i on of the 1 aser.

Laser dentistry: A new application of excimer laser in root canal therapy

International Nuclear Information System (INIS)

Pini, R.; Salimbeni, R.; Vannini, M.; Barone, R.; Clauser, C.

1989-01-01

We report the first study of the application of excimer lasers in dentistry for the treatment of dental root canals. High-energy ultraviolet (UV) radiation emitted by an XeCl excimer laser (308 nm) and delivered through suitable optical fibers can be used to remove residual organic tissue from the canals. To this aim, UV ablation thresholds of dental tissues have been measured, showing a preferential etching of infiltrated dentin in respect to healthy dentin, at laser fluences of 0.5-1.5 J/cm 2 . This technique has been tested on extracted tooth samples, simulating a clinical procedure. Fibers of decreasing core diameters have been used to treat different sections of the root canal down to its apical portion, resulting in an effective, easy, and fast cleaning action. Possible advantages of excimer laser clinical applications in respect to usual procedures are also discussed

Deposition of high Tc superconductor thin films by pulsed excimer laser ablation and their post-synthesis processing

International Nuclear Information System (INIS)

Ogale, S.B.

1992-01-01

This paper describes the use of pulsed excimer laser ablation technique for deposition of high quality superconductor thin films on different substrate materials such as Y stabilized ZrO 2 , SrTiO 3 , LiNbO 3 , Silicon and Stainless Steels, and dopant incorporation during the film depositions. Processing of deposited films using ion and laser beams for realisation of device features are presented. 28 refs., 16 figs

Combination treatment with excimer laser and narrowband UVB light in vitiligo patients.

Science.gov (United States)

Shin, Sungsik; Hann, Seung-Kyung; Oh, Sang Ho

2016-01-01

For the treatment of vitiligo, narrowband UVB (NBUVB) light is considered the most effective for nonsegmental vitiligo, while excimer laser treatment is commonly used for localized vitiligo. However, treatment areas may potentially be missed with excimer laser treatment. We aimed to evaluate the effect of combinational treatment with NBUVB light and excimer laser on vitiligo. All patients were first treated with NBUVB; excimer laser was then applied in conjunction with NBUVB phototherapy due to a slow response or no further improvement with continuous NBUVB treatment alone. To minimize adverse effects, a fixed dose of NBUVB was administered, and the dose of excimer laser was increased based on patient response. Among 80 patients, 54 patients showed responses after combination with excimer laser; however, 26 patients (32.5%) showed no remarkable change after combination therapy. Of the 26 patients who showed no further response, 12 patients (46.1%) presented with vitiligo on the acral areas, which are known to the least responsive sites. Our study suggests that combined treatment of NBUVB and excimer laser in vitiligo may enhance the treatment response without remarkable side effects, therefore might also increase the compliance of the patients to the treatment. © 2015 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

Photochemical and Spectroscopic Effects Resulting from Excimer Laser Excitation.

Science.gov (United States)

Wang, Xuan Xiao

I. Photochemical production of ozone from pure oxygen using excimer lasers. Production of ozone was observed from experiments when oxygen was under a broadband pulsed KrF laser radiation. The production process was found to be autocatalytic. Mechanisms for the ozone formation were proposed. Experimental results over a range of oxygen pressure and laser pulse energy (irradiance) provided evidences in favor of the proposed mechanisms. Experiments were also numerically modeled. Good agreement between the experimental and the numerical results were observed, which provided further evidence to support the proposed mechanisms. Cross sections for some photochemical processes in the mechanisms were estimated. Production of ozone from pure oxygen under a ArF excimer laser radiation (193 nm) was also studied and numerically modeled. Effects of ambient water vapor on ozone production were investigated. Experimental results showed a fast ozone destruction when water vapor was present in the cell. However, numerical results obtained from the well-known OH and HO _2 chain ozone destruction mechanism predicted a slower ozone destruction. Possible reasons for the discrepancy are discussed. II. Resonance-enhanced multiphoton ionization of N_2 at 193 and 248 nm detected by N_sp{2}{+} fluorescence. Using a broadband excimer laser operating at 193 and 248 nm multiphoton ionization at high pressures in air and pure nitrogen has been detected by fluorescence from N_sp{2}{+} in the B-X firstnegative system. Measurements of the fluorescence intensity as a function of beam irradiance indicate resonance in N_2 at the energy of two 193 nm photons (2 + 1 REMPI) and three 248 nm photons (3 + 1 REMPI). Possible intermediate states are discussed. III. Excimer laser-induced fluorescence from some organic solvents. Fluorescence was observed from vapor phase benzene, toluene, p-xylene, benzyl chloride, methyl benzoate, acetic anhydride, ether, methanol, ethyl acetone, acetone, and 2-butanone using

Excimer laser irradiation of metal surfaces

Science.gov (United States)

Kinsman, Grant

In this work a new method of enhancing CO2 laser processing by modifying the radiative properties of a metal surface is studied. In this procedure, an excimer laser (XeCl) or KrF) exposes the metal surface to overlapping pulses of high intensity, 10(exp 8) - 10(exp 9) W cm(exp -2), and short pulse duration, 30 nsec FWHM (Full Width Half Maximum), to promote structural and chemical change. The major processing effect at these intensities is the production of a surface plasma which can lead to the formation of a laser supported detonation wave (LSD wave). This shock wave can interact with the thin molten layer on the metal surface influencing to a varying degree surface oxidation and roughness features. The possibility of the expulsion, oxidation and redeposition of molten droplets, leading to the formation of micron thick oxide layers, is related to bulk metal properties and the incident laser intensity. A correlation is found between the expulsion of molten droplets and a Reynolds number, showing the interaction is turbulent. The permanent effects of these interactions on metal surfaces are observed through scanning electron microscopy (SEM), transient calorimetric measurements and Fourier transform infrared (FTIR) spectroscopy. Observed surface textures are related to the scanning procedures used to irradiate the metal surface. Fundamental radiative properties of a metal surface, the total hemispherical emissivity, the near-normal spectral absorptivity, and others are examined in this study as they are affected by excimer laser radiation. It is determined that for heavily exposed Al surface, alpha' (10.6 microns) can be increased to values close to unity. Data relating to material removal rates and chemical surface modification for excimer laser radiation is also discussed. The resultant reduction in the near-normal reflectivity solves the fundamental problem of coupling laser radiation into highly reflective and conductive metals such as copper and aluminum. The

Excimer laser surface modification: Process and properties

Energy Technology Data Exchange (ETDEWEB)

Jervis, T.R.; Nastasi, M. [Los Alamos National Lab., NM (United States); Hirvonen, J.P. [Technical Research Institute, Espoo (Finland). Metallurgy Lab.

1992-12-01

Surface modification can improve materials for structural, tribological, and corrosion applications. Excimer laser light has been shown to provide a rapid means of modifying surfaces through heat treating, surface zone refining, and mixing. Laser pulses at modest power levels can easily melt the surfaces of many materials. Mixing within the molten layer or with the gas ambient may occur, if thermodynamically allowed, followed by rapid solidification. The high temperatures allow the system to overcome kinetic barriers found in some ion mixing experiments. Alternatively, surface zone refinement may result from repeated melting-solidification cycles. Ultraviolet laser light couples energy efficiently to the surface of metallic and ceramic materials. The nature of the modification that follows depends on the properties of the surface and substrate materials. Alloying from both gas and predeposited layer sources has been observed in metals, semiconductors, and ceramics as has surface enrichment of Cr by zone refinement of stainless steel. Rapid solidification after melting often results in the formation of nonequilibrium phases, including amorphous materials. Improved surface properties, including tribology and corrosion resistance, are observed in these materials.

Subjective results of excimer laser correction of myopia. Review

Directory of Open Access Journals (Sweden)

V. N. Trubilin

2012-01-01

Full Text Available In review presents data of various authors regarding the subjective results excimer laser correction of myopia by LASIK. It was revealed that a group of patients with a high degree of dissatisfaction amounts to 4.6% of the total in all studies. High subjective results are confirmed by the positive dynamics of the «quality of life» of the patient.

New polymers containing BF2-benzoylacetonate groups. Synthesis, luminescence, excimer and exciplex formation

International Nuclear Information System (INIS)

Fedorenko, Elena V.; Mirochnik, Anatolii G.; Beloliptsev, Anton Yu.

2017-01-01

In the present study, a new synthetic method for the functionalization of polystyrene (PS) and (styrene-methyl methacrylate) copolymer has been developed. Using the new method, polymers containing BF 2 -benzoylacetonate groups have been obtained through double acylation by acetic anhydride with boron trifluoride. Luminescence of the produced polymers in solutions and films has been studied. Quantum yields of polymer solution luminescence are significantly higher than those of the low-molecular-weight analog – boron difluoride benzoylacetonate. For the polymer, in which styrene fragments are separated by methyl methacrylate groups, at low concentrations of the polymer in solution one observes the monomer luminescence of BF 2 -benzoylacetonate groups, while at high concentrations – the excimer luminescence. In case of PS-based polymers, in which BF 2 -benzoylacetonate groups and phenyl rings are not separated, in diluted solutions one observes the fluorescence of the intramolecular exciplexes, while at the concentration increase – the luminescence of intermolecular exciplexes. The ability of excimer formation is responsible for the increased photostability of the produced polymers. - Highlights: •Polymers containing BF 2 -benzoylacetonate groups have been synthesized. •Luminescence of the produced polymers in solutions and films has been studied. •Formation of excimers and exciplexes in solution has been revealed. •Formation of excimers in films increases their photostability.

Bound-bound transitions in the emission spectra of Ba+-He excimer

Science.gov (United States)

Moroshkin, P.; Kono, K.

2016-05-01

We present an experimental and theoretical study of the emission and absorption spectra of the Ba+ ions and Ba+*He excimer quasimolecules in the cryogenic Ba-He plasma. We observe several spectral features in the emission spectrum, which we assign to the electronic transitions between bound states of the excimer correlating to the 6 2P3 /2 and 5 2D3 /2 ,5 /2 states of Ba+. The resulting Ba+(5 2DJ) He is a metastable electronically excited complex with orbital angular momentum L =2 , thus expanding the family of known metal-helium quasimolecules. It might be suitable for high-resolution spectroscopic studies and for the search for new polyatomic exciplex structures.

Krypton Gas for High Quality Single Wall Carbon Nanotubes Synthesis by KrF Excimer Laser Ablation

Directory of Open Access Journals (Sweden)

Jasim Al-Zanganawee

2015-01-01

Full Text Available We report for the first time the production of single wall carbon nanotubes (SWCNTs by KrF excimer laser ablation method under the krypton gas atmosphere. For the ablation experiment 450 mJ energy and 30 Hz repetition rate KrF excimer laser was used, and the target was prepared with the following composition: 0.6% Ni, 0.6% Co, and 98.8% C (atomic percentage. The ablation product was characterized by confocal Raman microspectroscopy, transmission electron microscopy (TEM, scanning electron microscopy (SEM, and thermogravimetric analysis (TGA. The SWCNTs obtained are a mixture of semiconducting and metallic types with narrow diameters distribution of 1.26 to 1.49 nm, are micrometers long, and contain low amount of graphite and amorphous carbon.

Treatment of alopecia areata with the 308-nm xenon chloride excimer laser: case report of two successful treatments with the excimer laser.

Science.gov (United States)

Gundogan, Cuneyt; Greve, Bärbel; Raulin, Christian

2004-01-01

Alopecia areata is a common disease of unknown etiology; it causes significant cosmetic and psycho-social distress for most of the people it affects. We report on an innovative form of treatment in two patients with typical alopecia areata on the capillitium. We successfully treated two patients whose alopecia areata had worsened progressively for 3 and 14 weeks. The treatment involved the use of a 308 nm xenon chloride excimer laser (dosage 300-2,300 mJ/cm(2) per session). After 11 and 12 sessions within a 9-week and 11-week period, the entire affected focus showed homogenous and thick regrowth. No relapse was observed during the follow-up period of 5 and 18 months. The use of the excimer laser is an effective, elegant, and safe means of treatment and has good tolerability. Analogous to topical treatment of alopecia areata, the immunosuppressive mechanism of the excimer laser can be interpreted as an induction of T-cell apoptosis. This new means of treatment has yet to be discussed in medical literature. Further studies with greater numbers are needed to assess its potential more precisely and evaluate the excimer laser in treating alopecia areata. Copyright 2004 Wiley-Liss, Inc.

Intramolecular excimer and exciplex emission of 1,4-dipyrenyl substituted cyclohexasilane

NARCIS (Netherlands)

van Walree, C.A.; Kaats-Richters, V.E.M.; Jenneskens, L.W.; Williams, R.M.; van Stokkum, I.H.M.

2002-01-01

Intramolecular excimer emission is observed for cis-1,4-di(1-pyrenyl)decamethylcyclohexasilane in nonpolar solvents. Time-resolved fluorescence spectroscopy and kinetic modelling indicate that the driving force of excimer formation is very small, and that the process is governed by the flexibility

Excimer laser phototherapeutic keratectomy.

Science.gov (United States)

Ayres, Brandon D; Rapuano, Christopher J

2006-10-01

Anterior corneal pathology, such as corneal scars and corneal stromal dystrophies, can be visually devastating. Over the past decade, there was a shift in treatment of these conditions from corneal transplantation to phototherapeutic keratectomy (PTK) using the 193 nm excimer laser for visual restoration. We have reviewed the recent literature on techniques for performing and refining PTK and also on various pathologic conditions that can be treated with PTK. The primary indications for PTK include anterior corneal dystrophies, such as lattice, granular, and Reis-Bückler's dystrophy. PTK can produce significant visual improvement in these patients, and corneal transplantation or retransplantation can be delayed. Corneal degenerations, such as Salzmann's nodular degeneration, keratoconus nodules, and climatic droplet keratopathy, also can be successfully treated with PTK. Additionally, anterior corneal scars from such etiologies as trauma, corneal ulcers, and prior refractive surgery can have visual improvement with PTK. In summary, PTK is a powerful tool for the management of anterior corneal pathology. In a properly selected and well-counseled patient, PTK can significantly improve vision and quality of life.

Excimer fluorescence of liquid crystalline systems

Science.gov (United States)

Sakhno, Tamara V.; Khakhel, Oleg A.; Barashkov, Nikolay N.; Korotkova, Irina V.

1996-04-01

The method of synchronous scanning fluorescence spectroscopy shows a presence of dimers of pyrene in a polymeric matrix. The results suggest that excimer formation takes place with dimers in liquid crystalline systems.

Excimer lamp pumped by a triggered discharge

Energy Technology Data Exchange (ETDEWEB)

Baldacchini, G.; Bollanti, S.; Di Lazzaro, P.; Flora, F.; Giordano, G.; Letardi, T.; Renieri, A.; Schina, G. [ENEA, Centro Ricerche Frascati, Rome (Italy). Dip. Innovazione; Clementi, G.; Muzzi, F.; Zheng, C.E. [EL.EN. (Electronic Engineering), Florence (Italy)

1996-11-01

Radiation characteristics and discharge performances of an excimer lamp are described. The discharge of the HCl/Xe gas mixture at an atmospheric pressure, occurring near the quartz tube wall, is initiated by a trigger wire. A maximum total UV energy of about 0.4 J in a (0.8-0.9) {mu}s pulse, radiated from a 10 cm discharge length, is obtained with a total discharge input energy of 8 J. Excimer lamps are the preferred choice for medical and material processing irradiations, when the monochromaticity or coherence of UV light is not required, due to their low cost, reliability and easy maintenance.

Excimer laser for the treatment of psoriasis: safety, efficacy, and patient acceptability

Directory of Open Access Journals (Sweden)

Abrouk M

2016-12-01

Full Text Available Michael Abrouk,1 Ethan Levin,2 Merrick Brodsky,1 Jessica R Gandy,1 Mio Nakamura,2 Tian Hao Zhu,3 Benjamin Farahnik,4 John Koo,2 Tina Bhutani2 1Irvine School of Medicine, Irvine, 2Department of Dermatology, Psoriasis and Skin Treatment Center, University of California, San Francisco, 3Department of Dermatology, University of Southern California Keck School of Medicine, Los Angeles, CA, 4Department of Dermatology, University of Vermont College of Medicine, Burlington, VT, USA Introduction: The 308 nm excimer laser is a widely used device throughout the field of dermatology for many diseases including psoriasis. Although the laser has demonstrated clinical efficacy, there is a lack of literature outlining the safety, efficacy, and patient acceptability of the excimer laser. Methods: A literature search on PubMed was used with combinations of the terms “excimer”, “excimer laser”, “308 nm”, “psoriasis”, “protocol”, “safety”, “efficacy”, acceptability”, “side effects”, and “dose”. The search results were included if they contained information pertaining to excimer laser and psoriasis treatment and description of the safety, efficacy, and patient acceptability of the treatment. Results: The 308 nm excimer laser is generally safe and well tolerated with minimal side effects including erythema, blistering, and pigmentary changes. It has a range of efficacies depending on the protocol used with several different treatment protocols, including the induration protocol, the minimal erythema dose protocol, and the newer minimal blistering dose protocol. Conclusion: Although the excimer laser is not a first-line treatment, it remains an excellent treatment option for psoriasis patients and has been demonstrated to be an effective treatment with little to no side effects. Keywords: excimer, laser, 308 nm, psoriasis, safety, efficacy

308-nm excimer lamp for the treatment of alopecia areata: Clinical trial on 16 cases

Directory of Open Access Journals (Sweden)

Akiko Ohtsuki

2013-01-01

Full Text Available Background: Alopecia areata (AA is considered as a T-cell mediated autoimmune disorder. The 308-nm excimer laser is thought to be capable of inducing T-cell apoptosis in vitro, suggesting that the 308-nm excimer lamp (not laser might be effective for the treatment of AA. We examined the effectiveness of the 308-nm excimer lamp for treating AA. Materials and Methods: We treated 16 patients with single AA and multiple AA (MAA. The lesions were irradiated with a 308-nm excimer lamp at 2-week intervals. Results: Hair regrowth was observed in 14 patients. Among them, 10 patients showed more than 50% hair re-growth. Our results suggested that the 308-nm excimer lamp system is effective and safe for the treatment of single AA and MAA. Conclusion: Our results suggest that the 308-nm excimer lamp is a good therapeutic alternative without serious side effect for treating AA.

308-nm excimer laser for the treatment of alopecia areata.

Science.gov (United States)

Al-Mutairi, Nawaf

2007-12-01

Alopecia areata is loss of hair from localized or diffuse areas of hair-bearing area of the skin. Recently there are reports of efficacy of the 308-nm excimer radiation for this condition. To study the effect of the 308-nm excimer laser in the treatment of alopecia areata. Eighteen patients with 42 recalcitrant patches (including 1 adult with alopecia totalis) were enrolled in this study. The lesions were treated with the 308-nm excimer laser twice a week for a period of 12 weeks; one lesion on each patient was left as a control for comparison. There were 7 males and 11 females in this study. Regrowth of hair was observed in 17 (41.5%) patches. Thirteen of the 18 lesions in scalp showed a complete regrowth of hair. The extremity regions failed to show a response. Atopic diatheses had an unfavorable effect on the outcome in our patients. The 308-nm excimer laser is an effective therapeutic option for patchy alopecia areata of the scalp and for some cases with patchy alopecia areata of the beard area. It does not work for patchy alopecia areata of the extremities.

Effectiveness of 308-nm Excimer Laser Therapy in Treating Alopecia Areata, Determined by Examining the Treated Sides of Selected Alopecic Patches.

Science.gov (United States)

Byun, Ji Won; Moon, Jong Hyuk; Bang, Chan Yl; Shin, Jeonghyun; Choi, Gwang Seong

2015-01-01

Some studies have reported the use of 308-nm excimer laser therapy for treating alopecia areata (AA); however, the effectiveness of this therapy on a theoretical basis has not yet been comparatively analyzed. To determine the therapeutic effect of excimer laser therapy on AA. One alopecic patch was divided into control and treated sides in 10 patients with AA. Then, 308-nm excimer laser therapy was administered twice a week for 12 weeks. Photograph and phototrichogram analyses were performed. Photographic assessments by both dermatologists and individuals of the general population showed objective improvements after excimer laser therapy. On the treated side, the hair count and hair diameter had statistically increased after treatment. However, only the hair diameter was found to be significantly high in the treated half when it was compared with the control side. The 308-nm excimer laser has a therapeutic effect on AA, which is proven by photograph and phototrichogram analysis by a side-by-side comparison. © 2015 S. Karger AG, Basel.

Molecule-binding dependent assembly of split aptamer and γ-cyclodextrin: A sensitive excimer signaling approach for aptamer biosensors

International Nuclear Information System (INIS)

Jin, Fen; Lian, Yan; Li, Jishan; Zheng, Jing; Hu, Yaping; Liu, Jinhua; Huang, Jin; Yang, Ronghua

2013-01-01

Graphical abstract: Adenosine-binding aptamer was splitted into two fragments P2 and P3 which labeled pyrene molecules, mainly produce monomer signal. γ-CD cavity brings P2 and P3 in close proximity, allowing for weak excimer emission. In the presence of target, P2 and P3 are expected to bind ATP and form an aptamer/target complex, leads to large increase of the pyrene excimer fluorescence. -- Highlights: •We assembled split aptamer and γ-cyclodextrin fluorescence biosensors for ATP detection. •The biosensor increased quantum yield and emission lifetime of the excimer. •Time-resolved fluorescence is effective for ATP assay in complicated environment. -- Abstract: A highly sensitive and selective fluorescence aptamer biosensors for the determination of adenosine triphosphate (ATP) was developed. Binding of a target with splitting aptamers labeled with pyrene molecules form stable pyrene dimer in the γ-cyclodextrin (γ-CD) cavity, yielding a strong excimer emission. We have found that inclusion of pyrene dimer in γ-cyclodextrin cavity not only exhibits additive increases in quantum yield and emission lifetime of the excimer, but also facilitates target-induced fusion of the splitting aptamers to form the aptamer/target complex. As proof-of-principle, the approach was applied to fluorescence detection of adenosine triphosphate. With an anti-ATP aptamer, the approach exhibits excimer fluorescence response toward ATP with a maximum signal-to-background ratio of 32.1 and remarkably low detection limit of 80 nM ATP in buffer solution. Moreover, due to the additive fluorescence lifetime of excimer induced by γ-cyclodextrin, time-resolved measurements could be conveniently used to detect as low as 0.5 μM ATP in blood serum quantitatively

On the origin of excimer emission in electroluminescence and photoluminescence spectra of polyfluorenes

International Nuclear Information System (INIS)

Vacha, Martin; Ha, Jaekook; Sato, Hisaya

2007-01-01

We report a study on the differences in red-shifted excimer band in photoluminescence (PL) and electroluminescence (EL) spectra of thin films of a copolymer of dibutylfluorene and butylphenylphenoxazine. The relative intensity of the excimer band in PL spectra increases with temperature above the polymer glass transition, and with the intensity of the excitation light. In EL spectra, on the other hand, the relative excimer intensity is seen to decrease with increasing driving voltage. These opposite trends originate from the different nature of excitations in PL and EL spectra: photoexcitation directly creates singlet excitons while electric excitation proceeds via interaction of injected electrons and holes. In case of electric excitation, the observed results might be due to trap-assisted excimer formation

Formation and control of excimer of a coumarin derivative in Langmuir–Blodgett films

Energy Technology Data Exchange (ETDEWEB)

Chakraborty, Santanu; Bhattacharjee, D.; Hussain, Syed Arshad, E-mail: sa_h153@hotmail.com

2014-01-15

In this communication we report the formation and control of excimer of a coumerin derivative 7-Hydroxy-N-Octadecyl Coumarin-3-Carboxamide (7HNO3C) assembled onto Langmuir–Blodgett (LB) films. Surface pressure–area per molecule isotherm revealed that 7HNO3C formed stable Langmuir monolayer at the air–water interface. Spectroscoipic characterizations confirmed the formation of excimer of 7HNO3C in the LB film prepared at 20 mN/m surface pressure. The excimer band remains present even when 7HNO3C molecules are diluted with a long chain fatty acid stearic acid in LB films. The excimer formation of 7HNO3C can be controlled by incorporating clay particle laponite in the LB film. The excimer band is totally absent in the hybrid 7HNO3C–laponite LB films. In-situ fluorescence imaging microscopy and atomic force microscopy confirmed the incorporation of clay laponite onto LB films. -- Highlights: • Formation of Langmuir monolayer and Langmuir–Blodgett (LB) film of a coumarin derivative. • Presence of excimeric species in the LB film lifted at 20 mN/m surface pressure is confirmed from the spectroscopic studies. • Control of excimer formation by incorporating clay particle laponite on to the LB film. • In-situ fluorescence imaging microscopy and atomic force microscopy confirmed the incorporation of clay laponite onto LB films.

New polymers containing BF{sub 2}-benzoylacetonate groups. Synthesis, luminescence, excimer and exciplex formation

Energy Technology Data Exchange (ETDEWEB)

Fedorenko, Elena V., E-mail: gev@ich.dvo.ru [Institute of Chemistry, Far Eastern Branch of the Russian Academy of Sciences, 159, Prosp. 100 letiya Vladivostoka, Vladivostok 690022 (Russian Federation); Mirochnik, Anatolii G.; Beloliptsev, Anton Yu. [Institute of Chemistry, Far Eastern Branch of the Russian Academy of Sciences, 159, Prosp. 100 letiya Vladivostoka, Vladivostok 690022 (Russian Federation)

2017-05-15

In the present study, a new synthetic method for the functionalization of polystyrene (PS) and (styrene-methyl methacrylate) copolymer has been developed. Using the new method, polymers containing BF{sub 2}-benzoylacetonate groups have been obtained through double acylation by acetic anhydride with boron trifluoride. Luminescence of the produced polymers in solutions and films has been studied. Quantum yields of polymer solution luminescence are significantly higher than those of the low-molecular-weight analog – boron difluoride benzoylacetonate. For the polymer, in which styrene fragments are separated by methyl methacrylate groups, at low concentrations of the polymer in solution one observes the monomer luminescence of BF{sub 2}-benzoylacetonate groups, while at high concentrations – the excimer luminescence. In case of PS-based polymers, in which BF{sub 2}-benzoylacetonate groups and phenyl rings are not separated, in diluted solutions one observes the fluorescence of the intramolecular exciplexes, while at the concentration increase – the luminescence of intermolecular exciplexes. The ability of excimer formation is responsible for the increased photostability of the produced polymers. - Highlights: •Polymers containing BF{sub 2}-benzoylacetonate groups have been synthesized. •Luminescence of the produced polymers in solutions and films has been studied. •Formation of excimers and exciplexes in solution has been revealed. •Formation of excimers in films increases their photostability.

Scattered UV irradiation during VISX excimer laser keratorefractive surgery.

Science.gov (United States)

Hope, R J; Weber, E D; Bower, K S; Pasternak, J P; Sliney, D H

2008-04-01

To evaluate the potential occupational health hazards associated with scattered ultraviolet (UV) radiation during photorefractive keratectomy (PRK) using the VISX Star S3 excimer laser. The Laser Vision Center, National Naval Medical Center, Bethesda, Maryland, USA. Intraoperative radiometric measurements were made with the Ophir Power/Energy Meter (LaserStar Model PD-10 with silicon detector) during PRK treatments as well as during required calibration procedures at a distance of 20.3 cm from the left cornea. These measurements were evaluated using a worst-case scenario for exposure, and then compared with the American Conference of Governmental Industrial Hygeinists (ACGIH) Threshold Value Limits (TVL) to perform a risk/hazard analysis. During the PRK procedures, the highest measured value was 248.4 nJ/pulse. During the calibration procedures, the highest measured UV scattered radiation level was 149.6 nJ/pulse. The maximum treatment time was 52 seconds. Using a worst-case scenario in which all treatments used the maximum power and time, the total energy per eye treated was 0.132 mJ/cm2 and the total UV radiation at close range (80 cm from the treated eye) was 0.0085 mJ/cm2. With a workload of 20 patients, the total occupational exposure at 80 cm to actinic UV radiation in an 8-hour period would be 0.425 mJ/cm2. The scattered actinic UV laser radiation from the VISX Star S3 excimer laser did not exceed occupational exposure limits during a busy 8-hour workday, provided that operating room personnel were at least 80 cm from the treated eye. While the use of protective eyewear is always prudent, this study demonstrates that the trace amounts of scattered laser emissions produced by this laser do not pose a serious health risk even without the use of protective eyewear.

Tunable excimer lasers

International Nuclear Information System (INIS)

Sze, R.C.

1990-01-01

The wide bandwidth nature of the rare-gas halide excimer transitions allow reasonable tuning of the laser oscillation wavelength that makes it useful for a number of applications. At the same time this wide bandwidth makes narrow band operation difficult and special techniques are needed to insure narrow frequency lasing as well as absolute frequency resettability. The author discusses briefly some of the classical frequency narrowing techniques and then goes on to some recent work that require lasers of special frequency characteristics for special applications including KrF laser fusion

Survey on modern pulsed high power lasers

International Nuclear Information System (INIS)

Witte, K.J.

1985-01-01

The requirements to be met by lasers for particle acceleration are partially similar to those already known for fusion lasers. The power level wanted in both caes is up to 100 TW or even more. The pulse durations favourable for laser accelerators are in the range from 1 ps to 1000 ps whereas fusion lasers require several ns. The energy range for laser accelerators is thus correspondingly smaller than that for fusion lasers: 1-100 kJ versus several 100 kJ. The design criteria of lasers meeting the requirements are discussed in the following. The CO 2 , iodine, Nd:glass and excimer lasers are treated in detail. The high repetition rate aspect will not be particularly addressed since for the present generation of lasers the wanted rates of far above 1 Hz are completely out of scope. Moreover, for the demonstration of principle these rates are not needed. (orig./HSI)

Double discharges in unipolar-pulsed dielectric barrier discharge xenon excimer lamps

International Nuclear Information System (INIS)

Liu Shuhai; Neiger, Manfred

2003-01-01

Excitation of dielectric barrier discharge xenon excimer lamps by unipolar short square pulses is studied in this paper. Two discharges with different polarity are excited by each voltage pulse (double discharge phenomenon). The primary discharge occurs at the top or at the rising flank of the applied unipolar square pulse, which is directly energized by the external circuit. The secondary discharge with the reversed polarity occurs at the falling flank or shortly after the falling flank end (zero external voltage) depending on the pulse width, which is energized by the energy stored by memory charges deposited by the primary discharge. Fast-speed ICCD imaging shows the primary discharge has a conic discharge appearance with a channel broadening on the anode side. This channel broadening increases with increasing the pulse top level. Only the anode-side surface discharge is observed in the primary discharge. The surface discharge on the cathode side which is present in bipolar sine voltage excitation is not observed. On the contrary, the secondary discharge has only the cathode-side surface discharge. The surface discharge on the anode side is not observed. The secondary discharge is much more diffuse than the primary discharge. Time-resolved emission measurement of double discharges show the secondary discharge emits more VUV xenon excimer radiation but less infrared (IR) xenon atomic emission than the primary discharge. It was found that the IR xenon atomic emission from the secondary discharge can be reduced by shortening the pulse width. The energy efficiency of unipolar-pulsed xenon excimer lamps (the overall energy efficiency of double discharges) is much higher than that obtained under bipolar sine wave excitation. The output VUV spectrum under unipolar pulse excitation is found to be identical to that under sine wave excitation and independent of injected electric power

A retrospective comparison of efficacy and safety of 680 consecutive lasik treatments for high myopia performed with two generations of flying-spot excimer lasers.

Science.gov (United States)

Gazieva, Lola; Beer, Mette Hjuler; Nielsen, Kim; Hjortdal, Jesper

2011-12-01

To compare the visual refractive outcome and complication of laser in situ keratomileusis (LASIK) carried out with a Carl Zeiss-Meditec MEL-70 Excimer laser and a MEL-80 laser for treatment of high myopia. Journal records of 680 consecutive eyes that underwent LASIK with a Schwind Supratome microkeratome and a MEL-70 Excimer laser (Group A), or a Moria M2 microkeratome and a MEL-80 Excimer laser (Group B) were reviewed. Manifest refraction, uncorrected and best spectacle-corrected visual acuity (BSCVA), corneal topography and central corneal thickness (CCT) were recorded before and 3 months after treatment. Pre- and postoperative complications, visual and refractive outcome and frequency of retreatments were registered. Mean preoperative spherical equivalent refraction was -8.52 dioptres (-5.50- -18 dioptres), and the mean attempted laser correction was -8.02 dioptres (-5.50- -11 dioptres). Three months after LASIK, the average treatment error (difference between achieved and attempted correction) was 1.20 (SD=1.19) dioptres of under correction in Group A and 0.52 (SD=1.00) dioptres in Group B. Four eyes lost more than two lines of BSCVA (0.6%). In 110 eyes (16%), a re-LASIK procedure was performed to reduce remaining myopia after the primary procedure. Laser in situ keratomileusis treatment for high myopia can effectively reduce high degrees of myopia. Under correction was observed in both treatment groups but Group B has a slightly better predictability. Significant loss of BSCVA occurs infrequently after LASIK for even considerable grades of myopia (0.6% in each group). © 2010 The Authors. Journal compilation © 2010 Acta Ophthalmol.

Stability of a 1-kW excimer laser with long optical pulses

NARCIS (Netherlands)

Timmermans, J.C.M.; Hofmann, T.; Hofmann, Th.; van Goor, F.A.; Witteman, W.J.

1996-01-01

For high repetition operation of excimer-lasers care has to be taken of the changing performance of the electrical circuit, gas dynamic effects and contamination of the gas mixture to avoid deterioration of the laser performance. The parameters that influence the stability of the discharge are

Change of wettability of PTFE surface by sputter etching and excimer laser. Sputter etching oyobi excimer laser ni yoru PTFE hyomen no shinsuika

Energy Technology Data Exchange (ETDEWEB)

Yamamoto, S. (Nitto Denko Corp., Osaka (Japan)); Kubo, U. (Kinki University, Osaka (Japan))

1994-06-20

The wettability of PTFE (polytetrafluoroethylene) surfaces was improved by sputter etching and excimer laser irradiation. In sputter etching, the PTFE surface was treated by reactive sputter etching with H2O gas to give active groups on the surface. In laser irradiation, the surface was irradiated in pure water by high-energy KrF excimer laser. As the surface wettability was evaluated with a contact angle to water, the contact angle decreased remarkably in both treatments resulting in a good improvement effect. In sputter etching, various new chemical bonds such as F-C=O, F2C-FC-O, F2C-C-O and C-O were observed because of a decrease in F and incorporation of oxygen. Such chemical bonds could be eliminated by ultraviolet ray irradiation, and the treated surface condition approached the initial condition after irradiation of 200 hours. In laser irradiation, it was suggested that C-F bonds were broken, and OH groups were added to the surface by dissociation of H2O to H and OH. 7 refs., 8 figs., 1 tab.

Keratomodelling with low-intensity ultraviolet radiation of excimer laser

International Nuclear Information System (INIS)

Vitrishchak, I.B.; Vorontsov, V.V.; Murzin, A.G.; Polikarpov, S.S.; Soms, L.N.

1990-01-01

A study was made on possibility of keratomodelling with low-intensive UV-radiation of excimer laser with subablation energy density in a pulse. Model specimens of polymers and cornea tissue were used. It is shown that the range of threshold energy density in a pulse expands with increase of UV-radiation wave length and contracts with increase of pulse repetition frequency. This range appeared to be different for polymers and cornea tissue. It was revealed that cornea tissue represented a complex high-molecular bipolymer with high water content

Ultraviolet excimer laser ablation: the effect of wavelength and repetition rate on in vivo guinea pig skin

Energy Technology Data Exchange (ETDEWEB)

Morelli, J.; Kibbi, A.G.; Farinelli, W.; Boll, J.; Tan, O.T.

1987-06-01

Multiple dermatologic conditions that are currently treated with traditional cold-knife surgery are amenable to laser therapy. The ideal surgical treatment would be precise and total removal of abnormal tissue with maximal sparing of remaining structures. The ultraviolet (UV) excimer laser is capable of such precise tissue removal due to the penetration depth of 193 nm and 248 nm irradiation of 1 micron per pulse. This type of ablative tissue removal requires a high repetition rate for efficient lesional destruction. Excimer laser radiation at 193 nm is capable of high repetition rates, which are necessary while 248 nm radiation causes increasing nonspecific thermal injury as the laser repetition rate is increased.

A general excimer signaling approach for aptamer sensors.

Science.gov (United States)

Wu, Cuichen; Yan, Ling; Wang, Chunming; Lin, Haoxue; Wang, Chi; Chen, Xi; Yang, Chaoyong James

2010-06-15

Simple, fast and direct analysis or monitoring of significant molecules in complex biological samples is important for many biological study, clinical diagnosis and forensic investigations. Herein we highlight a general method to tailor aptamer sequence into functional subunits to design target-induced light-switching excimer sensors for rapid, sensitive and selective detection of important molecules in complex biological fluids. Our approach is to split one single strand aptamer into two pieces and each terminally labeled with a pyrene molecule while maintaining their binding affinity to target molecules. In the presence of target molecules, two aptamer fragments are induced to self-assemble to form aptamer-target complex and bring two pyrene molecules into a close proximity to form an excimer, resulting in fluorescent switching from approximately 400 nm to 485 nm. With an anti-cocaine sensor, as low as 1 microM of cocaine can be detected using steady-state fluorescence assays and more importantly low picomole level of target can be directly visualized with naked eyes. Because the excimer has a long fluorescence lifetime, time-resolved measurements were used to directly detect as low as 5 microM cocaine in urine samples quantitatively without any sample pretreatment. Copyright 2010 Elsevier B.V. All rights reserved.

A design of energy detector for ArF excimer lasers

Science.gov (United States)

Feng, Zebin; Han, Xiaoquan; Zhou, Yi; Bai, Lujun

2017-08-01

ArF excimer lasers with short wavelength and high photon energy are widely applied in the field of integrated circuit lithography, material processing, laser medicine, and so on. Excimer laser single pulse energy is a very important parameter in the application. In order to detect the single pulse energy on-line, one energy detector based on photodiode was designed. The signal processing circuit connected to the photodiode was designed so that the signal obtained by the photodiode was amplified and the pulse width was broadened. The amplified signal was acquired by a data acquisition card and stored in the computer for subsequent data processing. The peak of the pulse signal is used to characterize the single pulse energy of ArF excimer laser. In every condition of deferent pulse energy value levels, a series of data about laser pulses energy were acquired synchronously using the Ophir energy meter and the energy detector. A data set about the relationship between laser pulse energy and the peak of the pulse signal was acquired. Then, by using the data acquired, a model characterizing the functional relationship between the energy value and the peak value of the pulse was trained based on an algorithm of machine learning, Support Vector Regression (SVR). By using the model, the energy value can be obtained directly from the energy detector designed in this project. The result shows that the relative error between the energy obtained by the energy detector and by the Ophir energy meter is less than 2%.

Corneal aldehyde dehydrogenase and glutathione S-transferase activity after excimer laser keratectomy in guinea pigs.

Science.gov (United States)

Bilgihan, K; Bilgihan, A; Hasanreisoğlu, B; Turkozkan, N

1998-03-01

The free radical balance of the eye may be changed by excimer laser keratectomy. Previous studies have demonstrated that excimer laser keratectomy increases the corneal temperature, decreases the superoxide dismutase activity of the aqueous, and induces lipid peroxidation in the superficial corneal stroma. Aldehyde dehydrogenase (ALDH) and glutathione S-transferase (GST) are known to play an important role in corneal metabolism, particularly in detoxification of aldehydes, which are generated from free radical reactions. In three groups of guinea pigs mechanical corneal de-epithelialisation was performed in group I, superficial corneal photoablation in group II, and deep corneal photoablation in group III, and the corneal ALDH and GST activities measured after 48 hours. The mean ALDH and GST activities of group I and II showed no differences compared with the controls (p > 0.05). The corneal ALDH activities were found to be significantly decreased (p < 0.05) and GST activities increased (p < 0.05) in group III. These results suggest that excimer laser treatment of high myopia may change the ALDH and GST activities, metabolism, and free radical balance of the cornea.

Advanced excimer laser technologies enable green semiconductor manufacturing

Science.gov (United States)

Fukuda, Hitomi; Yoo, Youngsun; Minegishi, Yuji; Hisanaga, Naoto; Enami, Tatsuo

2014-03-01

"Green" has fast become an important and pervasive topic throughout many industries worldwide. Many companies, especially in the manufacturing industries, have taken steps to integrate green initiatives into their high-level corporate strategies. Governments have also been active in implementing various initiatives designed to increase corporate responsibility and accountability towards environmental issues. In the semiconductor manufacturing industry, there are growing concerns over future environmental impact as enormous fabs expand and new generation of equipments become larger and more powerful. To address these concerns, Gigaphoton has implemented various green initiatives for many years under the EcoPhoton™ program. The objective of this program is to drive innovations in technology and services that enable manufacturers to significantly reduce both the financial and environmental "green cost" of laser operations in high-volume manufacturing environment (HVM) - primarily focusing on electricity, gas and heat management costs. One example of such innovation is Gigaphoton's Injection-Lock system, which reduces electricity and gas utilization costs of the laser by up to 50%. Furthermore, to support the industry's transition from 300mm to the next generation 450mm wafers, technologies are being developed to create lasers that offer double the output power from 60W to 120W, but reducing electricity and gas consumption by another 50%. This means that the efficiency of lasers can be improve by up to 4 times in 450mm wafer production environments. Other future innovations include the introduction of totally Heliumfree Excimer lasers that utilize Nitrogen gas as its replacement for optical module purging. This paper discusses these and other innovations by Gigaphoton to enable green manufacturing.

Assessment of the suitability of excimer lasers in treating onychomycosis

International Nuclear Information System (INIS)

Kymplová, Jaroslava; Dušek, Karel; Jelínek, Miroslav; Urzová, Jana; Mikšovský, Jan; Bauerová, Lenka

2014-01-01

Since it is known that UV-C radiation kills fungus, we wanted to verify the hypothesis that the use of excimer laser could be an alternative method for treating onychomycosis - nail fungus. The aim of the first stage of this work was to determine the transmission, reflection and absorption of nails. In the following stage we focused on irradiation of fungi. Our final task is to assess whether it is possible to determine the parameters of radiation (a total dose,a dose per pulse frequency, a repetition rate, a number of pulses) for which the elimination of fungi would be the most effective but without damaging the nail and soft tissue underneath it. The results so far have showed that UV-C radiation does not pass through a fingernail to such an extent that it could damage the soft tissue beneath it. Fungi are destroyed by the application of only small doses of radiation using the excimer laser. Additional measurements will be required to determine the modulation parameters of the excimer laser radiation for the treatment of onychomycosis.

Improving the ablation efficiency of excimer laser systems with higher repetition rates through enhanced debris removal and optimized spot pattern.

Science.gov (United States)

Arba-Mosquera, Samuel; Klinner, Thomas

2014-03-01

To evaluate the reasons for the required increased radiant exposure for higher-repetition-rate excimer lasers and determine experimentally possible compensations to achieve equivalent ablation profiles maintaining the same single-pulse energies and radiant exposures for laser repetition rates ranging from 430 to 1000 Hz. Schwind eye-tech-solutions GmbH and Co. KG, Kleinostheim, Germany. Experimental study. Poly(methyl methacrylate) (PMMA) plates were photoablated. The pulse laser energy was maintained during all experiments; the effects of the flow of the debris removal, the shot pattern for the correction, and precooling the PMMA plates were evaluated in terms of achieved ablation versus repetition rate. The mean ablation performance ranged from 88% to 100%; the variability between the profile measurements ranged from 1.4% to 6.2%. Increasing the laser repetition rate from 430 Hz to 1000 Hz reduced the mean ablation performance from 98% to 91% and worsened the variability from 1.9% to 4.3%. Increasing the flow of the debris removal, precooling the PMMA plates to -18°C, and adapting the shot pattern for the thermal response of PMMA to excimer ablation helped stabilize the variability. Only adapting the shot pattern for the thermal response of PMMA to excimer ablation helped stabilize the mean ablation performance. The ablation performance of higher-repetition-rate excimer lasers on PMMA improved with improvements in the debris removal systems and shot pattern. More powerful debris removal systems and smart shot patterns in terms of thermal response improved the performance of these excimer lasers. Copyright © 2014 ASCRS and ESCRS. Published by Elsevier Inc. All rights reserved.

Comparative study of excimer and erbium:YAG lasers for ablation of structural components of the knee

Science.gov (United States)

Vari, Sandor G.; Shi, Wei-Qiang; van der Veen, Maurits J.; Fishbein, Michael C.; Miller, J. M.; Papaioannou, Thanassis; Grundfest, Warren S.

1991-05-01

This study was designed to compare the efficiency and thermal effect of a 135 ns pulsed-stretched XeCl excimer laser (308 nm) and a free-running Erbium:YAG laser (2940 nm) with 200 microsecond(s) pulse duration for ablation of knee joint structures (hyaline and fibrous cartilage, tendon and bone). The radiant exposure used for tissue ablation ranged from 2 to 15 J/cm2 for the XeCl excimer and from 33 to 120 J/cm2 for Er:YAG. The excimer and Er:YAG lasers were operated at 4 and 5 Hz respectively. The ablative laser energy was delivered to tissue through fibers. Ablation rates of soft tissues (hyaline and fibrous cartilage, tendon) varied from 8.5 to 203 micrometers /pulse for excimer and from 8.2 to 273 micrometers /pulse for Er:YAG lasers. Ablation rates of soft tissues are linearly dependent on the radiant exposure. Within the range of parameters tested all the tissues except the bone could be rapidly ablated by both lasers. Bone ablation was much less efficient, requiring 15 J/cm2 and 110 J/cm2 radiant exposure for excimer and Er:YAG lasers to ablate 9.5 and 8.2 micrometers tissue per pulse. However, excimer laser ablation produced less thermal damage in the tissues studied compared to Er:YAG at the same laser parameters. The authors conclude that both lasers are capable of efficient knee joint tissue ablation. XeCl excimer laser requires an order of magnitude less energy than Er:YAG laser for comparable tissue ablation.

Treatment of onychomycosis using radiation of excimer laser

Czech Academy of Sciences Publication Activity Database

Urzová, J.; Jelínek, Miroslav; Mikšovský, Jan; Kymplová, J.

2013-01-01

Roč. 647, JAN (2013), s. 636-641 ISSN 1022-6680 R&D Projects: GA MŠk LD12069 Institutional support: RVO:68378271 Keywords : excimer laser * UV-C radiation * nails * onychomycosis Subject RIV: BM - Solid Matter Physics ; Magnetism

Four-year to seven-year outcomes of advanced surface ablation with excimer laser for high myopia

DEFF Research Database (Denmark)

Hansen, Rasmus Søgaard; Lyhne, Niels; Grauslund, Jakob

2015-01-01

Purpose: To evaluate and compare long-term outcomes ofafter photorefractive keratectomy with cooling (cPRK) and laser-assisted subepithelial keratectomy (LASEK) for high myopia. Methods: Retrospective single-masked follow-up study of patients treated for myopia between 2007 and 2009 with cPRK...... or LASEK, using a high-frequency flying-spot excimer laser with eye-tracker (MEL80; Carl Zeiss, Jena, Germany). One eye of each patient was randomly chosen for analysis. Re-treated eyes were excluded. Results: Forty-six cPRK patients and 35 LASEK patients were included. Spherical equivalent averaged -7.......69 ± 1.47 diopters (D) in cPRK eyes and -7.98 ± 2.06 D in LASEK eyes (P=0.31) before surgery. Average follow-up time was 4.6 years in cPRK patients and 6.0 years in LASEK patients (PPRK eyes and 1 LASEK eye (P=0.46) had lost 2 lines of corrected distance visual acuity...

Collagen crosslinking for ectasia following PRK performed in excimer laser-assisted keratoplasty for keratoconus.

Science.gov (United States)

Spadea, Leopoldo

2012-01-01

To report the results of corneal collagen crosslinking (CXL) in a patient with corneal ectasia developed after excimer laser-assisted lamellar keratoplasty for keratoconus and a secondary photorefractive keratectomy (PRK) for residual refractive error. A 33-year-old woman, who had originally been treated for keratoconus in the right eye by excimer laser-assisted lamellar keratoplasty, subsequently had her residual ametropia treated by topographically guided, transepithelial excimer laser PRK. Five years after PRK, the patient developed corneal ectasia showing concomitant visual changes of best spectacle-corrected visual acuity (BSCVA) reduced to 20/33 with a refraction of -6.00 +6.00 × 30. The minimum corneal thickness at the ectasia apex was 406 µm. A treatment of riboflavin-UVA-induced corneal CXL was performed on the right eye. Two years after the CXL treatment, the right eye improved to 20/20 BSCVA with a refraction of plano +1.00 × 50 while exhibiting a clear lamellar graft. Corneal CXL provided safe and effective management of ectasia developed after excimer laser-assisted lamellar keratoplasty and PRK.

High efficiency metal marking with CO2 laser and glass marking with excimer laser

DEFF Research Database (Denmark)

Bastue, Jens; Olsen, Flemmming Ove

1997-01-01

with a thoroughly tested ray-tracing model is presented and compared with experimental results. Special emphasis is put on two different applications namely marking in metal with TEA-CO2 laser and marking in glass with excimer laser. The results are evaluated on the basis of the achievable energy enhancement......Today, mask based laser materials processing and especially marking is widely used. However, the energy efficiency in such processes is very low [1].This paper gives a review of the results, that may be obtained using the energy enhancing technique [1]. Results of simulations performed...

The effect of microarc oxidation and excimer laser processing on the microstructure and corrosion resistance of Zr–1Nb alloy

International Nuclear Information System (INIS)

Yang, Jiaoxi; Wang, Xin; Wen, Qiang; Wang, Xibing; Wang, Rongshan; Zhang, Yanwei; Xue, Wenbin

2015-01-01

The main purpose of this research was to investigate the effect of microarc oxidation (MAO) and excimer laser processing on the corrosion resistance of Zr–1Nb alloy in service environment. The pre-oxide film was fabricated on the surface of Zr–1Nb cladding tubes by MAO processing, and then subjected to KrF excimer laser irradiation. The surface morphology of the pre-oxide film was observed using a scanning electron microscope; phase compositions and quantities were determined using an X-ray diffraction; surface roughness was determined using a profilometer; and thermal expansion coefficient was measured using a dilatometer. Autoclave experiments were conducted for 94 days in an aqueous condition of 360 °C under 18.6 MPa in 0.01 mol/L LiOH solutions. The results showed that MAO + laser treatment resulted in a significant increase in the corrosion resistance of Zr–1Nb cladding tubes at high temperatures, because laser melting and etching could lead to a reduction in surface roughness and an increase in compactness of the pre-oxide film, and laser processing could promote the transformation of m-ZrO 2 phase to t-ZrO 2 phase. The best corrosion resistance was obtained when the pulse energy was 500 mJ, scanning speed was 0.13 mm/s, and pulse number was 2400. - Highlights: • Pre-oxide film was fabricated on Zr–1Nb cladding tube by MAO+ excimer laser processing. • Excimer laser processing induced the transformation of m-ZrO 2 to t-ZrO 2 . • The Rietveld quantitative analysis of the pre-oxide film was made. • We investigated the high temperature corrosion and corrosion mechanism of the oxide film. • The parameters of MAO+ excimer laser processing were optimized.

The effect of microarc oxidation and excimer laser processing on the microstructure and corrosion resistance of Zr–1Nb alloy

Energy Technology Data Exchange (ETDEWEB)

Yang, Jiaoxi, E-mail: yangjiaoxi@bjut.edu.cn [Institute of Laser Engineering, Beijing University of Technology, Beijing 100124 (China); Wang, Xin; Wen, Qiang; Wang, Xibing [Institute of Laser Engineering, Beijing University of Technology, Beijing 100124 (China); Wang, Rongshan; Zhang, Yanwei [Suzhou Nuclear Power Research Institute, Suzhou 215004 (China); Xue, Wenbin [College of Nuclear Science and Technology, Beijing Normal University, Beijing 100875 (China); Beijing Radiation Center, Beijing 100875 (China)

2015-12-15

The main purpose of this research was to investigate the effect of microarc oxidation (MAO) and excimer laser processing on the corrosion resistance of Zr–1Nb alloy in service environment. The pre-oxide film was fabricated on the surface of Zr–1Nb cladding tubes by MAO processing, and then subjected to KrF excimer laser irradiation. The surface morphology of the pre-oxide film was observed using a scanning electron microscope; phase compositions and quantities were determined using an X-ray diffraction; surface roughness was determined using a profilometer; and thermal expansion coefficient was measured using a dilatometer. Autoclave experiments were conducted for 94 days in an aqueous condition of 360 °C under 18.6 MPa in 0.01 mol/L LiOH solutions. The results showed that MAO + laser treatment resulted in a significant increase in the corrosion resistance of Zr–1Nb cladding tubes at high temperatures, because laser melting and etching could lead to a reduction in surface roughness and an increase in compactness of the pre-oxide film, and laser processing could promote the transformation of m-ZrO{sub 2} phase to t-ZrO{sub 2} phase. The best corrosion resistance was obtained when the pulse energy was 500 mJ, scanning speed was 0.13 mm/s, and pulse number was 2400. - Highlights: • Pre-oxide film was fabricated on Zr–1Nb cladding tube by MAO+ excimer laser processing. • Excimer laser processing induced the transformation of m-ZrO{sub 2} to t-ZrO{sub 2}. • The Rietveld quantitative analysis of the pre-oxide film was made. • We investigated the high temperature corrosion and corrosion mechanism of the oxide film. • The parameters of MAO+ excimer laser processing were optimized.

Pressure dependence of emission intensity of rare-gas excimer light produced by silent discharge; Teikiatsu ryoiki ni okeru musei hoden reiki ki gas excimer hikari shutsuryoku no atsuryoku izonsei

Energy Technology Data Exchange (ETDEWEB)

Yoshida, Y.; Tanaka, M.; Yukimura, K. [Doshisha University, Kyoto (Japan)

1996-09-20

To establish the pressure dependence of silent discharge excited rare gas excimer light emission, a vacua ultraviolet light was subjected to spectroscopic analysis at a pressure lower than 20kPa. Researches are under way to apply the discharge excited rare gas excimer lamp as a vacuum ultraviolet light source for the development of new materials and for the conservation of environments. When the pressure is as low as 1.8kPa or 4.4kPa, the emission has peaks at wavelengths centering on 147nm and 149nm, both of which are the resonance lines of the xenon atom. Excimer generation becomes prominent as the pressure increases, with the second continuum of light growing dominant at 35kPa to weaken relatively the resonance lines and the first continuum of light. In the first continuum, emission increases only at a suppressed rate, as compared with emission in the second continuum, due for instance to a collision caused relaxation process in which excimers are lost. In the case of xenon in the vicinity of 10-11kPa, the first continuum of light and the second continuum of light are approximately equal in emission intensity, producing a vacuum ultraviolet light source with a bandwidth relatively large for a single gas spectrum. 14 refs., 11 figs.

Electrical and kinetical aspects of homogeneous dielectric-barrier discharge in xenon for excimer lamps

International Nuclear Information System (INIS)

Belasri, A.; Harrache, Z.

2010-01-01

A pulsed dielectric-barrier discharge in xenon has been simulated for operating conditions typical to excimer lamps, in which the discharge is considered spatially homogeneous. The computer model developed is based on the xenon plasma chemistry, the circuit, and the Boltzmann equations. First, the validity of the physical model was checked and compared to experimental and theoretical works, and then the model is applied in the case of a sinusoidal voltage at period frequencies in the range of 50 kHz-2 MHz. The results obtained with the present description are in good agreement with experimental measurements and one-dimensional fluid prediction in terms of electrical characteristics and vacuum ultraviolet (vuv) emission. The effect of operation voltage, power source frequency, dielectric capacitance, as well as gas pressure on the discharge efficiency and the 172, 150, and 147 nm photon generation, under the typical experimental operating conditions and for the case of a sinusoidal applied voltage, have been investigated and discussed. Calculations suggest that the overall conversion efficiency from electrical energy to vuv emission in the lamp is greater than 38%, and it will be very affected at high power source frequency and high gas pressure with a significant dependence on the dielectric capacitance.

A 223-nm KrCl excimer laser on a He-Kr-HCl mixture

International Nuclear Information System (INIS)

Razhev, A M; Zhupikov, A A; Kargapol'tsev, E S

2004-01-01

The results of experimental studies of the parameters of a 223-nm electric-discharge KrCl excimer laser on a He-Kr-HCl mixture depending on the excitation conditions and the composition of the active gaseous medium are presented. To achieve the maximum values of the output energy and the efficiency of the KrCl laser on mixtures with buffer gaseous helium, an excitation system was used that included a circuit with an LC inverter with a high-voltage switch based on an RU-65 spark gap. An output energy of 320 mJ with an efficiency of 0.5% relative to the energy stored in the capacitors is obtained in a KrCl laser with an active medium based on the buffer He gas at a charging voltage of 30 kV. Radiation pulses with a duration of 22±1 ns and a pulse power of 15 MW are obtained. (lasers)

Aerosol core nuclear reactor for space-based high energy/power nuclear-pumped lasers

International Nuclear Information System (INIS)

Prelas, M.A.; Boody, F.P.; Zediker, M.S.

1987-01-01

An aerosol core reactor concept can overcome the efficiency and/or chemical activity problems of other fuel-reactant interface concepts. In the design of a laser using the nuclear energy for a photon-intermediate pumping scheme, several features of the aerosol core reactor concept are attractive. First, the photon-intermediate pumping concept coupled with photon concentration methods and the aerosol fuel can provide the high power densities required to drive high energy/power lasers efficiently (about 25 to 100 kW/cu cm). Secondly, the intermediate photons should have relatively large mean free paths in the aerosol fuel which will allow the concept to scale more favorably. Finally, the aerosol core reactor concept can use materials which should allow the system to operate at high temperatures. An excimer laser pumped by the photons created in the fluorescer driven by a self-critical aerosol core reactor would have reasonable dimensions (finite cylinder of height 245 cm and radius of 245 cm), reasonable laser energy (1 MJ in approximately a 1 millisecond pulse), and reasonable mass (21 kg uranium, 8280 kg moderator, 460 kg fluorescer, 450 kg laser medium, and 3233 kg reflector). 12 references

Cationic Organochalcogen with Monomer/Excimer Emissions for Dual-Color Live Cell Imaging and Cell Damage Diagnosis.

Science.gov (United States)

Chao, Xi-Juan; Wang, Kang-Nan; Sun, Li-Li; Cao, Qian; Ke, Zhuo-Feng; Cao, Du-Xia; Mao, Zong-Wan

2018-04-25

Studies on the development of fluorescent organic molecules with different emission colors for imaging of organelles and their biomedical application are gaining lots of focus recently. Here, we report two cationic organochalcogens 1 and 2, both of which exhibit very weak green emission (Φ 1 = 0.12%; Φ 2 = 0.09%) in dilute solution as monomers, but remarkably enhanced green emission upon interaction with nucleic acids and large red-shifted emission in aggregate state by the formation of excimers at high concentration. More interestingly, the monomer emission and excimer-like emission can be used for dual color imaging of different organelles. Upon passively diffusing into cells, both probes selectively stain nucleoli with strong green emission upon 488 nm excitation, whereas upon 405 nm excitation, a completely different stain pattern by staining lysosomes (for 1) or mitochondria (for 2) with distinct red emission is observed because of the highly concentrated accumulation in these organelles. Studies on the mechanism of the accumulation in lysosomes (for 1) or mitochondria (for 2) found that the accumulations of the probes are dependent on the membrane permeabilization, which make the probes have great potential in diagnosing cell damage by sensing lysosomal or mitochondrial membrane permeabilization. The study is demonstrative, for the first time, of two cationic molecules for dual-color imaging nucleoli and lysosomes (1)/mitochondria (2) simultaneously in live cell based on monomer and excimer-like emission, respectively, and more importantly, for diagnosing cell damage.

Offset-gated poly-Si TFTs using in-situ fluorine passivation and excimer laser doping

International Nuclear Information System (INIS)

Jung, Sang Hoon; Kim, Cheon Hong; Yoo, Juhn Suk; Han, Min Koo

2000-01-01

A new low-temperature poly-Si thin film transistor (TFT) fabrication method employing in-situ fluorine passivation and excimer-laser doping is proposed to fabricate offset-gated poly-Si TFTs. In the new process, the crystallization, the in-situ fluorine passivation of the active layer, and the doping of the source/drain region are performed simultaneously with only one step of excimer laser annealing while the conventional fabrication method requires two laser annealing steps. Employing phosphosilicate glass (PSG) films as a diffusion source, we successfully accomplished excimer laser doping. The subthreshold and the on-state characteristics of the device with in-situ fluorine passivation were considerably improved. This improvement was due to the fluorine passivation effects, which cured dangling bonds and strained bonds in the poly-Si channel, the offset region, and the SiO 2 /poly-Si interface

Offset-gated poly-Si TFTs using in-situ fluorine passivation and excimer laser doping

CERN Document Server

Jung, S H; Yoo, J S; Han, M K

2000-01-01

A new low-temperature poly-Si thin film transistor (TFT) fabrication method employing in-situ fluorine passivation and excimer-laser doping is proposed to fabricate offset-gated poly-Si TFTs. In the new process, the crystallization, the in-situ fluorine passivation of the active layer, and the doping of the source/drain region are performed simultaneously with only one step of excimer laser annealing while the conventional fabrication method requires two laser annealing steps. Employing phosphosilicate glass (PSG) films as a diffusion source, we successfully accomplished excimer laser doping. The subthreshold and the on-state characteristics of the device with in-situ fluorine passivation were considerably improved. This improvement was due to the fluorine passivation effects, which cured dangling bonds and strained bonds in the poly-Si channel, the offset region, and the SiO sub 2 /poly-Si interface.

A quencher-free molecular beacon design based on pyrene excimer fluorescence using pyrene-labeled UNA (unlocked nucleic acid)

DEFF Research Database (Denmark)

Karlsen, Kasper Kannegård; Okholm, Anders Hauge; Kjems, Jørgen

2013-01-01

A quencher-free molecular beacon capable of generating pyrene excimer fluorescence has been constructed using strategically positioned pyrene-UNA monomers. Hybridization of a fully complementary RNA target was accompanied by a pyrene excimer emission increase of more than 900%, and detection of RNA...

308-nm excimer laser for the treatment of alopecia areata in children.

Science.gov (United States)

Al-Mutairi, Nawaf

2009-01-01

Alopecia areata (AA) is a common skin disease which is characterized by nonscarring localized or diffused hair loss. In this study we assessed the efficacy of 308-nm Excimer laser in the treatment of alopecia areata in children. A total of 9 children with 30 recalcitrant patches alopecia areata and two children with alopecia areata totalis were enrolled in this study which included seven male and four female patients, aged between 4 and 14 years and the durations of their disease were between 7 and 25 months. All of these patients had more than one lesion of alopecia areata and at least one of them was left as a control for comparison. The lesions were treated with the 308-nm Excimer laser twice a week for a period of 12 weeks. Regrowth of hair was observed in 18 (60%) alopecia patches in the scalp, while there was no response in the control patches and over the extremities. Only four patients with scalp lesions showed a recurrence of alopecia after 6 months post laser therapy. So, 308-nm Excimer laser is considered an effective safe therapeutic option for patchy alopecia areata in children.

Performance characteristics of an excimer laser (XeCl) with single ...

Indian Academy of Sciences (India)

2017-01-10

Jan 10, 2017 ... Performance characteristics of an excimer laser (XeCl) with single-stage magnetic ... the stress can increase the lifetime of the switches and ..... work. References. [1] Ying-Tung Chen, Kris Naessens, Roel Bates, Yunn-Shiuan.

Advanced excimer-based crystallization systems for production solutions

International Nuclear Information System (INIS)

Simon, F.; Brune, J.; Herbst, L.

2006-01-01

Line beam excimer laser annealing (ELA) is a well-known technique for thin Si-film crystallization and established in LTPS mass production. With introduction of sequential lateral solidification (SLS) some aspects such as crystalline quality, throughput and flexibility regarding the substrate size could be improved, but for OLED manufacturing still further process development is necessary. This paper discusses line beam ELA and SLS-techniques that might enable process engineers to make polycrystalline-silicon (poly-Si) films with a high degree of uniformity and quality as required for system on glass (SOG) and active matrix organic light emitting displays (AMOLED). Equipment requirements are discussed and compared to previous standards. SEM-images of process examples are shown in order to demonstrate the viability

Long Range Polymer Chain Dynamics of Highly Flexible Polysiloxane in Solution Probed by Pyrene Excimer Fluorescence

Directory of Open Access Journals (Sweden)

Janine L. Thoma

2018-03-01

Full Text Available A poly(dimethylsiloxane-co-(3-aminopropylmethylsiloxane polymer (PDMS with 20.3 mol % of (3-aminopropylmethyl siloxane monomer has been labeled randomly with 1-pyreneacetyl groups to generate a series of polysiloxanes (Py-PDMS with pyrenyl contents ranging from 0.7 mol % to 5.2 mol % of the total number of structural units. The remainder of the amino groups were acetylated to avoid intra-chain quenching of the excited singlet states of pyrene via exciplex formation with free amino groups while allowing the formation of excimers to proceed. The fluorescence spectra and temporal decays of the Py-PDMS samples were acquired in tetrahydrofuran (THF, N,N-dimethylformamide (DMF, and dioxane. blob, the average rate constant for intra-chain pyrene excimer formation, was determined from the analysis of the fluorescence decays. blob was found to equal 1.16 (±0.13 × 109, 1.14 (±0.12 × 109, and 0.99 (±0.10 × 109 s−1 in THF, DMF, and dioxane, respectively, at room temperature. They are the largest values found to date for any polymeric backbone in these solvents. The qualitative relationship found here between blob and the chemical structures of the polymers indicates that the luminescence characteristics of randomly labeled polymers is a very useful method to probe the long range dynamics of chains of almost any polymer that is amenable to substitution by a lumophore.

Excimer laser assisted very fast exfoliation and reduction of graphite oxide at room temperature under air ambient for Supercapacitors electrode

Science.gov (United States)

Malek Hosseini, S. M. B.; Baizaee, S. M.; Naderi, Hamid Reza; Dare Kordi, Ali

2018-01-01

Excimer laser was used for reduction and exfoliation of graphite oxide (GO) at room temperature under air ambient. The prepared excimer laser reduced graphite oxide (XLRGO) is characterized by scanning electron microscopy (SEM), atomic force microscopy (AFM), nitrogen adsorption/desorption (BET method), X-ray diffraction (XRD), X-ray photoemission spectroscopy (XPS), Fourier transform infrared spectroscopy (FTIR) and UV-vis absorption techniques for surface, structural functional groups and band gap analysis. Electrochemical properties are investigated using cyclic voltammetry, galvanostatic charge-discharge, electrochemical impedance spectroscopy (EIS) and continues cyclic voltammetry (CCV) in 0.5 M Na2SO4 as electrolyte. Electrochemical investigations revealed that XLRGO electrode has enhanced supercapacitive performance including specific capacitance of 299 F/g at a scan rate of 2 mV/s. Furthermore, CCV measurement showed that XLRGO electrode kept 97.8% of its initial capacitance/capacity after 4000 cycles. The obtained results from electrochemical investigations confirm that the reduction of GO by using an excimer laser produces high-quality graphene for supercapacitor applications without the need for additional operations.

Modeling of Kr-Xe discharge of excimer lamp

Directory of Open Access Journals (Sweden)

Belasri A.

2013-03-01

Full Text Available This paper reports the numerical simulation of Dielectric Barrier Discharge (DBD for Kr-Xe excilamp. The model of the discharge consists of three main modules: a plasma chemistry module, a circuit module and a Boltzmann equation module. The results predict the optimal operating conditions and describe the electrical and chemical properties of the KrXe* excimer lamp.

XeCl Excimer Laser For Micro - Machining Of Materials: Preliminary Theoretical And Experimental Works.

Science.gov (United States)

Iwanejko, Leszek; Pokora, Ludwik; Stefanski, Miroslaw; Ujda, Zbigniew

1987-10-01

The paper presents the results of preliminary investigations, both theoretical and experimental, of XeC1 excimer laser pumped by transverse electric discharge with UU preionization. The medium was a mixture of gases He-Xe-HC1. A theoretical model of the XeC1 laser was worked out and a lot of laser parameters calculations were done. In the same time an excimer laser operating on the mixture He-Xe-HC1 was started, the generation of laser radiation was of energy about 20mJ.

XeCl Excimer Laser with Three- and Four-Component Mixture of Active Gases

International Nuclear Information System (INIS)

Iwanejko, L.; Pokora, L.

1998-01-01

Selected results of investigations of a XeCl excimer laser employing a new type (four-component)of mixture of gases, He-Kr:Xe-HCl, are presented. The mixture includes, instead of Xe, a mixture of not-separated Kr and Xe gases, much less expensive than pure xenon. A comparison of durations and energies of pulses generated in the XeCl excimer laser using three- or four-component gaseous active medium (He-Xe-HCl or He-Kr:Xe-HCl) is made. The investigations have been carried out with the use of a laser system with UV preionization and self sustained pumping discharge. (author)

Application of optical tweezers and excimer laser to study protoplast fusion

Science.gov (United States)

Kantawang, Titirat; Samipak, Sompid; Limtrakul, Jumras; Chattham, Nattaporn

2015-07-01

Protoplast fusion is a physical phenomenon that two protoplasts come in contact and fuse together. Doing so, it is possible to combine specific genes from one protoplast to another during fusion such as drought resistance and disease resistance. There are a few possible methods to induce protoplast fusion, for example, electrofusion and chemical fusion. In this study, chemical fusion was performed with laser applied as an external force to enhance rate of fusion and observed under a microscope. Optical tweezers (1064 nm with 100X objective N.A. 1.3) and excimer laser (308 nm LMU-40X-UVB objective) were set with a Nikon Ti-U inverted microscope. Samples were prepared by soaking in hypertonic solution in order to induce cell plasmolysis. Elodea Canadensis and Allium cepa plasmolysed leaves were cut and observed under microscope. Concentration of solution was varied to induce difference turgor pressures on protoplasts pushing at cell wall. Free protoplasts in solution were trapped by optical tweezers to study the effect of Polyethylene glycol (PEG) solution. PEG was diluted by Ca+ solution during the process to induced protoplast cell contact and fusion. Possibility of protoplast fusion by excimer laser was investigated and found possible. Here we report a novel tool for plant cell fusion using excimer laser. Plant growth after cell fusion is currently conducted.

Definition and measurement of the times-diffraction-limit number of high-power laser beams

Science.gov (United States)

Bollanti, Sarah; Di Lazzaro, Paolo; Murra, Daniele

1998-07-01

A novel definition of the times-diffraction-limit (TDL) number of a laser beam is given. A comparison is made with the commonly used beam-propagation parameter M2, which is unreliable for hard-edge beams, like those produced by unstable resonators with diffraction output coupling. The new suggested TDL number definition doesn't rely on the real beam comparison to a Gaussian beam, but on the comparison of the far-field performances of the real beam with respect to those of a uniphase beam with the same amplitude profile in the near field. A practical method is also given for the estimation of the TDL number of real beams. Finally, this procedure is applied to the high-peak-power laser beams generated by two excimer laser systems developed in ENEA.

A comparison of the characteristics of excimer and femtosecond laser ablation of acrylonitrile butadiene styrene (ABS)

International Nuclear Information System (INIS)

See, Tian Long; Liu, Zhu; Li, Lin; Zhong, Xiang Li

2016-01-01

Highlights: • Ablation threshold for excimer laser is lower compared to femtosecond laser. • Effective optical penetration depth for excimer laser is lower compared to femtosecond laser. • Two ablation characteristic regimes are observed for femtosecond laser ablation. • Reduction of C=C bond following excimer or fs laser ablation is observed. • Addition of oxygen- and nitrogen-rich functional groups is observed. - Abstract: This paper presents an investigation on the ablation characteristics of excimer laser (λ = 248 nm, τ = 15 ns) and femtosecond laser (λ = 800 nm, τ = 100 fs) on ABS polymer sheets. The laser–material interaction parameters (ablation threshold, optical penetration depth and incubation factor) and the changes in material chemical properties were evaluated and compared between the two lasers. The work shows that the ablation threshold and effective optical penetration depth values are dependent on the wavelength of laser beam (photon energy) and the pulse width. The ablation threshold value is lower for the excimer laser ablation of ABS (F_t_h = 0.087 J/cm"2) than that for the femtosecond laser ablation of ABS (F_t_h = 1.576 J/cm"2), demonstrating a more dominating role of laser wavelength than the pulse width in influencing the ablation threshold. The ablation depth versus the logarithmic scale of laser fluence shows two linear regions for the fs laser ablation, not previously known for polymers. The effective optical penetration depth value is lower for excimer laser ablation (α"−"1 = 223 nm) than that for femtosecond laser ablation (α"−"1 = 2917 nm). The ablation threshold decreases with increasing number of pulses (NOP) due to the chain scission process that shortens the polymeric chains, resulting in a weaker polymeric configuration and the dependency is governed by the incubation factor. Excimer laser treatment of ABS eliminates the C=C bond completely through the chain scission process whereas C=C bond is partially

A comparison of the characteristics of excimer and femtosecond laser ablation of acrylonitrile butadiene styrene (ABS)

Energy Technology Data Exchange (ETDEWEB)

See, Tian Long, E-mail: tianlong.see@postgrad.manchester.ac.uk [Corrosion and Protection Centre, School of Materials, The Mill, The University of Manchester, M13 9PL Manchester (United Kingdom); Laser Processing Research Centre, School of Mechanical, Aerospace and Civil Engineering, The University of Manchester, M13 9PL Manchester (United Kingdom); Liu, Zhu [Corrosion and Protection Centre, School of Materials, The Mill, The University of Manchester, M13 9PL Manchester (United Kingdom); Li, Lin [Laser Processing Research Centre, School of Mechanical, Aerospace and Civil Engineering, The University of Manchester, M13 9PL Manchester (United Kingdom); Zhong, Xiang Li [Corrosion and Protection Centre, School of Materials, The Mill, The University of Manchester, M13 9PL Manchester (United Kingdom)

2016-02-28

Highlights: • Ablation threshold for excimer laser is lower compared to femtosecond laser. • Effective optical penetration depth for excimer laser is lower compared to femtosecond laser. • Two ablation characteristic regimes are observed for femtosecond laser ablation. • Reduction of C=C bond following excimer or fs laser ablation is observed. • Addition of oxygen- and nitrogen-rich functional groups is observed. - Abstract: This paper presents an investigation on the ablation characteristics of excimer laser (λ = 248 nm, τ = 15 ns) and femtosecond laser (λ = 800 nm, τ = 100 fs) on ABS polymer sheets. The laser–material interaction parameters (ablation threshold, optical penetration depth and incubation factor) and the changes in material chemical properties were evaluated and compared between the two lasers. The work shows that the ablation threshold and effective optical penetration depth values are dependent on the wavelength of laser beam (photon energy) and the pulse width. The ablation threshold value is lower for the excimer laser ablation of ABS (F{sub th} = 0.087 J/cm{sup 2}) than that for the femtosecond laser ablation of ABS (F{sub th} = 1.576 J/cm{sup 2}), demonstrating a more dominating role of laser wavelength than the pulse width in influencing the ablation threshold. The ablation depth versus the logarithmic scale of laser fluence shows two linear regions for the fs laser ablation, not previously known for polymers. The effective optical penetration depth value is lower for excimer laser ablation (α{sup −1} = 223 nm) than that for femtosecond laser ablation (α{sup −1} = 2917 nm). The ablation threshold decreases with increasing number of pulses (NOP) due to the chain scission process that shortens the polymeric chains, resulting in a weaker polymeric configuration and the dependency is governed by the incubation factor. Excimer laser treatment of ABS eliminates the C=C bond completely through the chain scission process whereas

Proceedings of the 3rd topical meeting on FEL and high power radiation

International Nuclear Information System (INIS)

Hiramatsu, Shigenori

1994-01-01

The meeting was held on June 10 and 11, 1993, at the National Laboratory for High Energy Physics. This is the joint study meeting with 31st large power microwave-milliwave study meeting. At the meeting, lectures were given on the report of 1st Asia FEL study meeting, infrared free electron laser (FEL) project in JAERI, present state of Free Electron Laser Research Institute Inc., infrared FEL experiment in the Institute of Scientific and Industrial Research, Osaka University, FEL experiment in UVSOR storage ring, NIJI-4 SRFEL, simulation of FEL oscillation in photo-klystron, vacuum UVFEL in PF, beam characteristics of small photon storage ring, micro-cherenkov FEL using field emission array, coherent spontaneous emission and radiation build-up in FEL oscillator, stability of soft X-ray multilayers under exposure to multipole Wigger radiation, long life Zn 2 excimer excited with relativistic electron beam, development of large power klystron in KEK, design of 1 THz gyrotron and first experiment, experiment of relativistic peniotron, experiments of 3rd and 10th cyclotron harmonic peniotron oscillators and others. (K.I.)

Improvement of Anti-TNF-α Antibody-Induced Palmoplantar Pustular Psoriasis Using a 308-nm Excimer Light

Directory of Open Access Journals (Sweden)

Natsuko Iga

2012-11-01

Full Text Available Anti-tumor necrosis factor (TNF-α antibody is utilized in the treatment of a variety of chronic inflammatory conditions, including psoriasis. However, it can induce paradoxical development and/or exacerbation of psoriasis in the course of anti-TNF-α antibody treatment, which is sometimes refractory to conventional treatments. Herein, we report a case of refractory palmoplantar pustular psoriasis induced by anti-TNF-α antibody treatment, which was improved by treatment with a 308-nm excimer light. The 308-nm excimer light has less long-term risks than narrow-band UVB. The 308-nm excimer light may be a good therapeutic option for refractory psoriatic skin lesions induced by anti-TNF-α antibody therapy because of localized side effects without systemic problems, short length of treatment and low cumulative dosages of UV light.

Comparing laser induced plasmas formed in diode and excimer pumped alkali lasers.

Science.gov (United States)

Markosyan, Aram H

2018-01-08

Lasing on the D 1 transition (6 2 P 1/2 → 6 2 S 1/2 ) of cesium can be reached in both diode and excimer pumped alkali lasers. The first uses D 2 transition (6 2 S 1/2 → 6 2 P 3/2 ) for pumping, whereas the second is pumped by photoexcitation of ground state Cs-Ar collisional pairs and subsequent dissociation of diatomic, electronically-excited CsAr molecules (excimers). Despite lasing on the same D 1 transition, differences in pumping schemes enables chemical pathways and characteristic timescales unique for each system. We investigate unavoidable plasma formation during operation of both systems side by side in Ar/C 2 H 6 /Cs.

Outcomes for Myopic LASIK With the MEL 90 excimer laser.

Science.gov (United States)

Reinstein, Dan Z; Carp, Glenn I; Lewis, Tariq A; Archer, Timothy J; Gobbe, Marine

2015-05-01

To evaluate the visual outcomes of myopic LASIK performed with the MEL 90 excimer laser (Carl Zeiss Meditec AG, Jena, Germany) using the Triple-A profile with a 500-Hz pulse rate. Retrospective analysis of the first 286 myopic LASIK procedures (147 patients) by two experienced surgeons in which the VisuMax femtosecond laser and MEL 90 excimer laser (Carl Zeiss Meditec) were used following a standardized surgical technique. Inclusion criteria were preoperative spherical equivalent refraction (SEQ) up to -10.38 diopters (D), cylinder up to 5.00 D, and corrected distance visual acuity (CDVA) of 20/25 or better. No nomogram adjustments were made. Patients were observed for 3 months. Flap thickness was between 80 and 110 µm and optical zone was between 6 and 7 mm. Standard outcomes analysis was performed. Preoperatively, mean SEQ was -3.83 ± 1.83 D (range: -0.13 to -10.38 D) and mean cylinder was -0.94 ± 0.86 D (range: 0.00 to -5.00 D). Mean age was 36.4 years (range: 18.2 to 74.1 years) with 50% female patients. Of this population, 138 eyes were treated by one surgeon and 148 eyes by another. The mean predictability of SEQ was -0.13 ± 0.34 D (range: -1.00 to +1.00 D). Postoperative SEQ was ± 0.50 D in 88% and ± 1.00 D in 100% of eyes. Preoperative CDVA was 20/20 or better in 97% of eyes. Postoperative uncorrected distance visual acuity was 20/20 or better in 92% and 20/25 or better in 99% of eyes. One line of CDVA was lost in 6% of eyes and no eyes lost two or more lines. There was statistically significant improvement in mesopic contrast sensitivity (CSV-1000) at 3 (P = .021), 6, 12, and 18 (all P ≤.001) cycles per degree. The MEL 90 excimer laser using the Triple-A ablation profile with a 500-Hz pulse rate was found to achieve a small but real increase in contrast sensitivity and high efficacy for myopia up to -10.00 D and cylinder up to 5.00 D without the need for a nomogram adjustment. Copyright 2015, SLACK Incorporated.

X-ray photoelectron spectroscopy study of excimer laser treated alumina films

Science.gov (United States)

Georgiev, D. G.; Kolev, K.; Laude, L. D.; Mednikarov, B.; Starbov, N.

1998-01-01

Amorphous alumina layers are deposited on a single crystal Si substrate by a e-gun evaporation technique. These films are then thermally annealed in oxygen to be crystallized and, further, irradiated with an excimer laser beam. At each stage of the film preparation, an x-ray photoelectron spectroscopy analysis is performed at the film surface and in depth, upon ion beam grinding. Results give evidence for the formation of an aluminosilicate upon thermal annealing of the film in oxygen. At the surface itself, this compound is observed to decompose upon excimer laser irradiation at energy densities exceeding 1.75 J/cm2, giving rise to free Si atoms and SiO2, however with complete disappearance of Al atoms. Model photochemical reactions are proposed to explain such transformations.

The development and progress of XeCl Excimer laser system

Science.gov (United States)

Zhang, Yongsheng; Ma, Lianying; Wang, Dahui; Zhao, Xueqing; Zhu, Yongxiang; Hu, Yun; Qian, Hang; Shao, Bibo; Yi, Aiping; Liu, Jingru

2015-05-01

A large angularly multiplexed XeCl Excimer laser system is under development at the Northwest Institute of Nuclear Technology (NINT). It is designed to explore the technical issues of uniform and controllable target illumination. Short wavelength, uniform and controllable target illumination is the fundamental requirement of high energy density physics research using large laser facility. With broadband, extended light source and multi-beam overlapping techniques, rare gas halide Excimer laser facility will provide uniform target illumination theoretically. Angular multiplexing and image relay techniques are briefly reviewed and some of the limitations are examined to put it more practical. The system consists of a commercial oscillator front end, three gas discharge amplifiers, two electron beam pumped amplifiers and the optics required to relay, encode and decode the laser beam. An 18 lens array targeting optics direct and focus the laser in the vacuum target chamber. The system is operational and currently undergoing tests. The total 18 beams output energy is more than 100J and the pulse width is 7ns (FWHM), the intensities on the target will exceed 1013W/cm2. The aberration of off-axis imaging optics at main amplifier should be minimized to improve the final image quality at the target. Automatic computer controlled alignment of the whole system is vital to efficiency and stability of the laser system, an array of automatic alignment model is under test and will be incorporated in the system soon.

Excimer laser superficial keratectomy for proud nebulae in keratoconus.

Science.gov (United States)

Moodaley, L; Liu, C; Woodward, E G; O'Brart, D; Muir, M K; Buckley, R

1994-06-01

Contact lens intolerance in keratoconus may be due to the formation of a proud nebula at or near the apex of the cone. Excimer laser superficial keratectomy was performed as an outpatients with proud nebulae as treatment patients with proud nebulae as treatment for their contact lens intolerance. The mean period of contact lens wear before the development of intolerance was 13.4 years (range 2 to 27 years). Following the development of intolerance, three patients abandoned contact lens wear in the affected eye while the remainder experienced a reduction in comfortable wearing time (mean = 3.75 hours; range: 0-14 hours). All patients had good potential Snellen visual acuity with a contact lens of 6/9 (nine eyes) and 6/12 (one eye). The proud nebulae were directly ablated with a 193 nm ArF excimer laser using a 1 mm diameter beam. Between 100-150 pulses were sufficient to ablate the raised area. Patients experienced no pain during the procedure and reported minimal discomfort postoperatively. In all cases flattening of the proud nebulae was achieved. Seven patients were able to resume regular contact lens wear (mean wearing time = 10.17 hours; range 8 to 16 hours). In three patients, resumption of contact lens wear was unsuccessful because of cone steepness. All patients achieved postoperative Snellen visual acuity of 6/12 or better with a contact lens. Four patients experienced a loss of one line in Snellen acuity. The mean follow up period was 8.3 months (range 2 to 17 months). Excimer laser superficial keratectomy is a useful technique for the treatment of contact lens intolerance caused by proud nebulae in patients with keratoconus. Penetrating keratoplasty is thus avoided.

Influence of gas discharge parameters on emissions from a dielectric barrier discharge excited argon excimer lamp

Directory of Open Access Journals (Sweden)

Mike Collier

2011-11-01

Full Text Available A dielectric barrier discharge excited neutral argon (Ar I excimer lamp has been developed and characterised. The aim of this study was to develop an excimer lamp operating at atmospheric pressure that can replace mercury lamps and vacuum equipment used in the sterilisation of medical equipment and in the food industry. The effects of discharge gas pressure, flow rate, excitation frequency and pulse width on the intensity of the Ar I vacuum ultraviolet (VUV emission at 126 nm and near infrared (NIR lines at 750.4 nm and 811.5 nm have been investigated. These three lines were chosen as they represent emissions resulting from de-excitation of excimer states that emit energetic photons with an energy of 9.8 eV. We observed that the intensity of the VUV Ar₂* excimer emission at 126 nm increased with increasing gas pressure, but decreased with increasing excitation pulse frequency and pulse width. In contrast, the intensities of the NIR lines decreased with increasing gas pressure and increased with increasing pulse frequency and pulse width. We have demonstrated that energetic VUV photons of 9.8 eV can be efficiently generated in a dielectric barrier discharge in Ar.

The excimer lamp induces cutaneous nerve degeneration and reduces scratching in a dry-skin mouse model.

Science.gov (United States)

Kamo, Atsuko; Tominaga, Mitsutoshi; Kamata, Yayoi; Kaneda, Kazuyuki; Ko, Kyi C; Matsuda, Hironori; Kimura, Utako; Ogawa, Hideoki; Takamori, Kenji

2014-12-01

Epidermal hyperinnervation, which is thought to underlie intractable pruritus, has been observed in patients with atopic dermatitis (AD). The epidermal expression of axonal guidance molecules has been reported to regulate epidermal hyperinnervation. Previously, we showed that the excimer lamp has antihyperinnervative effects in nonpruritic dry-skin model mice, although epidermal expression of axonal guidance molecules was unchanged. Therefore, we investigated the antipruritic effects of excimer lamp irradiation and its mechanism of action. A single irradiation of AD model mice significantly inhibited itch-related behavior 1 day later, following improvement in the dermatitis score. In addition, irradiation of nerve fibers formed by cultured dorsal root ganglion neurons increased bleb formation and decreased nerve fiber expression of nicotinamide mononucleotide adenylyl transferase 2, suggesting degenerative changes in these fibers. We also analyzed whether attaching a cutoff excimer filter (COF) to the lamp, thus decreasing cytotoxic wavelengths, altered hyperinnervation and the production of cyclobutane pyrimidine dimer (CPD), a DNA damage marker, in dry-skin model mice. Irradiation with COF decreased CPD production in keratinocytes, as well as having an antihyperinnervative effect, indicating that the antipruritic effects of excimer lamp irradiation with COF are due to induction of epidermal nerve degeneration and reduced DNA damage.

Bulk damage and absorption in fused silica due to high-power laser applications

Science.gov (United States)

Nürnberg, F.; Kühn, B.; Langner, A.; Altwein, M.; Schötz, G.; Takke, R.; Thomas, S.; Vydra, J.

2015-11-01

Laser fusion projects are heading for IR optics with high broadband transmission, high shock and temperature resistance, long laser durability, and best purity. For this application, fused silica is an excellent choice. The energy density threshold on IR laser optics is mainly influenced by the purity and homogeneity of the fused silica. The absorption behavior regarding the hydroxyl content was studied for various synthetic fused silica grades. The main absorption influenced by OH vibrational excitation leads to different IR attenuations for OH-rich and low-OH fused silica. Industrial laser systems aim for the maximum energy extraction possible. Heraeus Quarzglas developed an Yb-doped fused silica fiber to support this growing market. But the performance of laser welding and cutting systems is fundamentally limited by beam quality and stability of focus. Since absorption in the optical components of optical systems has a detrimental effect on the laser focus shift, the beam energy loss and the resulting heating has to be minimized both in the bulk materials and at the coated surfaces. In collaboration with a laser research institute, an optical finisher and end users, photo thermal absorption measurements on coated samples of different fused silica grades were performed to investigate the influence of basic material properties on the absorption level. High purity, synthetic fused silica is as well the material of choice for optical components designed for DUV applications (wavelength range 160 nm - 260 nm). For higher light intensities, e.g. provided by Excimer lasers, UV photons may generate defect centers that effect the optical properties during usage, resulting in an aging of the optical components (UV radiation damage). Powerful Excimer lasers require optical materials that can withstand photon energy close to the band gap and the high intensity of the short pulse length. The UV transmission loss is restricted to the DUV wavelength range below 300 nm and

Effect of excimer laser (Arf, 193 nm) on aqueous humor during photorefractive keratectomy biophysical and biochemical study

International Nuclear Information System (INIS)

Mahmoud, S.S.; Mahmoud, A.A.

2004-01-01

Ultraviolet light (193 nm) produced by an excimer laser has been used to produce precise tissue ablation with minimal thermal damage to adjacent tissue. The present study was designed to investigate the effect of excimer laser during photo refractive keratectomy (PRK) on aqueous humor constituents and also the effect of antioxidant enzyme superoxide dismutase (SOD)- applied topically- on these changes if exist. Five groups of schenchilla rabbits were involved in this study, where four groups underwent corneal stromal ablation using argon fluoride excimer laser (Ar F, 193 nm). Two of these four groups were treated with superoxide dismutase intra operatively. The fifth group was used as control one. The obtained results revealed depletion of aqueous humor ascorbate and glutathione contents. Aqueous humor refractive index, cholesterol, phospholipids, malondialdehyde (MDA) and total protein were measured. In conclusion, the excimer laser can induce changes in aqueous humor constituents during PRK. These changes lasted at least for 24 hours and as the time increased to 4 weeks, these changes became limited. The use of exogenous SOD seems to exert beneficial effect on aqueous humor refractive index and total protein

Early outcome of high energy Laser (Excimer) facilitated coronary angioplasty ON hARD and complex calcified and balloOn-resistant coronary lesions: LEONARDO Study

International Nuclear Information System (INIS)

Ambrosini, Vittorio; Sorropago, Giovanni; Laurenzano, Eugenio; Golino, Luca; Casafina, Alfredo; Schiano, Vittorio; Gabrielli, Gabriele; Ettori, Federica; Chizzola, Giuliano; Bernardi, Guglielmo; Spedicato, Leonardo; Armigliato, Pietro; Spampanato, Carmine; Furegato, Martina

2015-01-01

Aim: An innovative xenon–chlorine (excimer) pulsed laser catheter (ELCA X80) has been recently used for the treatment of complex coronary lesions, as calcified stenosis, chronic total occlusions and non-compliant plaques. Such complex lesions are difficult to adequately treat with balloon angioplasty and/or intracoronary stenting. The aim of this study was to examine the acute outcome of this approach on a cohort of patients with coronary lesions. Methods and Results: Eighty patients with 100 lesions were enrolled through four centers, and excimer laser coronary angioplasty was performed on 96 lesions (96%). Safety and effectiveness data were compared between patients treated with standard laser therapy and those treated with increased laser therapy. Laser success was obtained in 90 lesions (93.7%), procedural success was reached in 88 lesions (91.7%), and clinical success in was obtained in 87 lesions (90.6%). There was no perforation, major side branch occlusion, spasm, no-reflow phenomenon, dissection nor acute vessel closure. Increased laser parameters were used successfully for 49 resistant lesions without complications. Conclusions: This study suggests that laser-facilitated coronary angioplasty is a simple, safe and effective device for the management of complex coronary lesions. Furthermore, higher laser energy levels delivered by this catheter improved the device performance without increasing complications. - Highlights: • We planned this multicenter study to examine the acute outcome of an innovative xenon–chlorine (excimer) pulsed laser catheter (ELCA X80) for treatment of complex coronary lesions. • We enrolled 80 patients with 100 lesions and performed excimer laser coronary angioplasty in 96 lesions (96%). • Laser success was obtained in 90 lesions (93.7%), procedural success was reached in 88 lesions (91.7%), and clinical success was obtained in 87 lesions (90.6%). • Increased laser parameters were used successfully for 49 resistant

Early outcome of high energy Laser (Excimer) facilitated coronary angioplasty ON hARD and complex calcified and balloOn-resistant coronary lesions: LEONARDO Study

Energy Technology Data Exchange (ETDEWEB)

Ambrosini, Vittorio; Sorropago, Giovanni; Laurenzano, Eugenio [Montevergine Clinic, Mercogliano (Italy); Golino, Luca, E-mail: lucagolino.jazz@alice.it [Montevergine Clinic, Mercogliano (Italy); Moriggia-Pelascini Hospital, Gravedona, Como (Italy); Casafina, Alfredo; Schiano, Vittorio [Montevergine Clinic, Mercogliano (Italy); Gabrielli, Gabriele [University Hospital Ospedali Riuniti, Ancona (Italy); Ettori, Federica; Chizzola, Giuliano [Spedali Civili University Hospital, Brescia (Italy); Bernardi, Guglielmo; Spedicato, Leonardo [University Hospital S. Maria Misericordia, Udine (Italy); Armigliato, Pietro [Istituto Italiano Ricerche Mediche, Verona (Italy); Spampanato, Carmine [Telethon Institute of Genetics and Medicine (TIGEM), Naples (Italy); Furegato, Martina [Istituto Italiano Ricerche Mediche, Verona (Italy)

2015-04-15

Aim: An innovative xenon–chlorine (excimer) pulsed laser catheter (ELCA X80) has been recently used for the treatment of complex coronary lesions, as calcified stenosis, chronic total occlusions and non-compliant plaques. Such complex lesions are difficult to adequately treat with balloon angioplasty and/or intracoronary stenting. The aim of this study was to examine the acute outcome of this approach on a cohort of patients with coronary lesions. Methods and Results: Eighty patients with 100 lesions were enrolled through four centers, and excimer laser coronary angioplasty was performed on 96 lesions (96%). Safety and effectiveness data were compared between patients treated with standard laser therapy and those treated with increased laser therapy. Laser success was obtained in 90 lesions (93.7%), procedural success was reached in 88 lesions (91.7%), and clinical success in was obtained in 87 lesions (90.6%). There was no perforation, major side branch occlusion, spasm, no-reflow phenomenon, dissection nor acute vessel closure. Increased laser parameters were used successfully for 49 resistant lesions without complications. Conclusions: This study suggests that laser-facilitated coronary angioplasty is a simple, safe and effective device for the management of complex coronary lesions. Furthermore, higher laser energy levels delivered by this catheter improved the device performance without increasing complications. - Highlights: • We planned this multicenter study to examine the acute outcome of an innovative xenon–chlorine (excimer) pulsed laser catheter (ELCA X80) for treatment of complex coronary lesions. • We enrolled 80 patients with 100 lesions and performed excimer laser coronary angioplasty in 96 lesions (96%). • Laser success was obtained in 90 lesions (93.7%), procedural success was reached in 88 lesions (91.7%), and clinical success was obtained in 87 lesions (90.6%). • Increased laser parameters were used successfully for 49 resistant

Optical coherence tomography following percutaneous coronary intervention with Excimer laser coronary atherectomy

Energy Technology Data Exchange (ETDEWEB)

Rawlins, John, E-mail: john.rawlins@doctors.net.uk; Talwar, Suneel; Green, Mark; O’Kane, Peter

2014-01-15

The indications for Excimer laser coronary atherectomy (ELCA) have been refined in modern interventional practice. With the expanding role for optical coherence tomography (OCT) providing high-resolution intra-coronary imaging, this article examines the appearance of the coronary lumen after ELCA. Each indication for ELCA is discussed and illustrated with a clinical case, followed by detailed analysis of the OCT imaging pre and post ELCA. The aim of the article is to provide information to interventional cardiologists to facilitate decision making during PCI, when ELCA has been used as part of the interventional strategy.

Charge versus Energy Transfer Effects in High-Performance Perylene Diimide Photovoltaic Blend Films.

Science.gov (United States)

Singh, Ranbir; Shivanna, Ravichandran; Iosifidis, Agathaggelos; Butt, Hans-Jürgen; Floudas, George; Narayan, K S; Keivanidis, Panagiotis E

2015-11-11

Perylene diimide (PDI)-based organic photovoltaic devices can potentially deliver high power conversion efficiency values provided the photon energy absorbed is utilized efficiently in charge transfer (CT) reactions instead of being consumed in nonradiative energy transfer (ET) steps. Hitherto, it remains unclear whether ET or CT primarily drives the photoluminescence (PL) quenching of the PDI excimer state in PDI-based blend films. Here, we affirm the key role of the thermally assisted PDI excimer diffusion and subsequent CT reaction in the process of PDI excimer PL deactivation. For our study we perform PL quenching experiments in the model PDI-based composite made of poly[4,8-bis(5-(2-ethylhexyl)thiophen-2-yl)benzo[1,2-b;4,5-b']dithiophene-2,6-diyl-alt-(4-(2-ethylhexanoyl)-thieno[3,4-b]thiophene)-2-6-diyl] (PBDTTT-CT) polymeric donor mixed with the N,N'-bis(1-ethylpropyl)-perylene-3,4,9,10-tetracarboxylic diimide (PDI) acceptor. Despite the strong spectral overlap between the PDI excimer PL emission and UV-vis absorption of PBDTTT-CT, two main observations indicate that no significant ET component operates in the overall PL quenching: the PL intensity of the PDI excimer (i) increases with decreasing temperature and (ii) remains unaffected even in the presence of 10 wt % content of the PBDTTT-CT quencher. Temperature-dependent wide-angle X-ray scattering experiments further indicate that nonradiative resonance ET is highly improbable due to the large size of PDI domains. The dominance of the CT over the ET process is verified by the high performance of devices with an optimum composition of 30:70 PBDTTT-CT:PDI. By adding 0.4 vol % of 1,8-diiodooctane we verify the plasticization of the polymer side chains that balances the charge transport properties of the PBDTTT-CT:PDI composite and results in additional improvement in the device efficiency. The temperature-dependent spectral width of the PDI excimer PL band suggests the presence of energetic disorder in the

Magnetic circular Dichroism and Faraday rotation of cesium-argon excimers and cesium dimers

International Nuclear Information System (INIS)

Islam, M.A.

1981-01-01

Magnetic Circular Dichroism (MCD) and Faraday Rotation (FR) of excimer absorption bands in gases are measured to obtain the first direct information about the angular momentum quantum numbers and the angular momentum coupling schemes of excimer molecules. So far, there has been no experimental method to obtain information about the axial angular momentum and the angular momentum coupling schemes of excimer molecules. In this experiment, the MCD and the FR of cesium-argon excimer and cesium dimer absorption bands between 5000 A and 10,000 A are measured for the range of temperature from 116 0 to 355 0 C. Of particular interest is the blue wing of D 2 line in cesium which has been the subject of vigorous investigation. The measured MCD data at the blue wing of D 2 line clearly shows that the assignment of 2 μ/sub 1/2/ to this excited state assuming Hund's case (b) is a poor approximation. By a simple inspection of the MCD data, it is found that the coupling scheme is more nearly Hund's case (c) than Hynd's case (b). Several other new and interesting results are obtained. The blue wing associated with 5D transition in atomic cesium is devoid of MCD and exhibits strong MCD in the red wings. Thus, the assignment of 2 μ/sub 1/2/ and 2 π to the blue and red wings, respectively, assuming Hund's case (a) and (b), is a very good approximation. Again the yellow-green band associated with 7s-6s transition in atomic cesium shows no MCD. It is therefore also a good approximation to assign 2 μ/sub 1/2/ to the upper state assuming Hund's case (b). Much more information can be obtained by a detailed analysis of the MCD data

Alkali-vapor laser-excimer pumped alkali laser

International Nuclear Information System (INIS)

Yue Desheng; Li Wenyu; Wang Hongyan; Yang Zining; Xu Xiaojun

2012-01-01

Based on the research internal and overseas, the principle of the excimer pumped alkali laser (XPAL) is explained, and the advantages and disadvantages of the XPAL are analyzed. Taking into consideration the difficulties that the diode pumped alkali laser (DPAL) meets on its development, the ability to solve or avoid these difficulties of XPAL is also analyzed. By summing up the achievements of the XPAL, the possible further prospect is proposed. The XPAL is of possibility to improve the performance of the DPAL. (authors)

Singlet Fission via an Excimer-Like Intermediate in 3,6-Bis(thiophen-2-yl)diketopyrrolopyrrole Derivatives.

Science.gov (United States)

Mauck, Catherine M; Hartnett, Patrick E; Margulies, Eric A; Ma, Lin; Miller, Claire E; Schatz, George C; Marks, Tobin J; Wasielewski, Michael R

2016-09-14

Singlet fission (SF) in polycrystalline thin films of four 3,6-bis(thiophen-2-yl)diketopyrrolopyrrole (TDPP) chromophores with methyl (Me), n-hexyl (C6), triethylene glycol (TEG), and 2-ethylhexyl (EH) substituents at the 2,5-positions is found to involve an intermediate excimer-like state. The four different substituents yield four distinct intermolecular packing geometries, resulting in variable intermolecular charge transfer (CT) interactions in the solid. SF from the excimer state of Me, C6, TEG, and EH takes place in τSF = 22, 336, 195, and 1200 ps, respectively, to give triplet yields of 200%, 110%, 110%, and 70%, respectively. The transient spectra of the excimer-like state and its energetic proximity to the lowest excited singlet state in these derivatives suggests that this state may be the multiexciton (1)(T1T1) state that precedes formation of the uncorrelated triplet excitons. The excimer decay rates correlate well with the SF efficiencies and the degree of intermolecular donor-acceptor interactions resulting from π-stacking of the thiophene donor of one molecule with the DPP core acceptor in another molecule as observed in the crystal structures. Such interactions are found to also increase with the SF coupling energies, as calculated for each derivative. These structural and spectroscopic studies afford a better understanding of the electronic interactions that enhance SF in chromophores having strong intra- and intermolecular CT character.

Excimer laser phototherapeutic keratectomy : Indications, results and its role in the Indian scenario

Directory of Open Access Journals (Sweden)

Rao Srinivas

1999-01-01

Full Text Available PURPOSE: To report indications, technique, and results of excimer phototherapeutic keratectomy (PTK, and describe possible reasons for the small numbers of such procedures performed in a referral institute in India. METHODS: Retrospective review of case records of 10 patients (11 eyes who underwent excimer PTK at our institute between February 1994 and September 1997. RESULTS: Corneal scars were the most common indication for treatment. Best-corrected visual acuity (BCVA improved in 6 eyes (mean: 2 lines of Snellen acuity. All eyes had BCVA > or = 6/12 after treatment. None of the patients experienced loss of BCVA after treatment. Unaided visual acuity improved in 3 eyes and decreased in 2 eyes. Change in spherical equivalent refraction > or = 1 diopter occurred in 77.8% of eyes after treatment. Treating central corneal scars resulted in a significant hyperopic shift in refraction. CONCLUSIONS: Excimer PTK is a safe and effective procedure for the treatment of superficial corneal opacities. Post-treatment ametropia may require further correction with optical aids. Inappropriate referrals, deep corneal scars, and cost of the procedure could have contributed to the small numbers of PTK performed at our institute. Improved understanding of procedural strengths and limitations could lead to increased use of this procedure, with satisfying results in selected patients.

Surface modification of polyethylene terephthalate using excimer and CO2 laser

International Nuclear Information System (INIS)

Mirzadeh, H.; Dadsetan, M.

2002-01-01

Complete text of publication follows. Attempts have been made to evaluate microstructuring which affects cell behaviour, physical and chemical changes produced by laser irradiation onto the polyethylene terephthalate (PET) surface. The surfaces of PET were irradiated using the CO 2 laser and KrF excimer pulsed laser. The changes in chemical and physical properties of the irradiated PET surface were investigated by attenuated total reflectance infrared spectroscopy (ATR-IR) and contact angle measurements. ATR-IR Spectra showed that the crystallinity in the surface region decreased due to the CO 2 laser and excimer laser irradiation. Scanning electron microscopy observations showed that the morphology of the laser irradiated PET surface changed due to laser irradiation. The results obtained from the cell behaviour studies revealed that changes of physico-chemical properties of the laser treated PET film have significantly changed in comparison with the unmodified PET

172 nm excimer VUV-triggered photodegradation and micropatterning of aminosilane films

International Nuclear Information System (INIS)

Elsner, Christian; Naumov, Sergej; Zajadacz, Joachim; Buchmeiser, Michael R.

2009-01-01

Emission from Xe 2 * excimers exhibiting photon energies between 7 and 10 eV can be used to induce strong surface modification effects on polymeric materials in the top 100 nm layer. In order to identify suitable monomers for this VUV-based process, the photodegradation mechanism of different organosilanes of the general structure R-CH 2 -Si(OCH 3 ) 3 was elucidated by quantum chemical calculations. Herein, the photodegradation of 3-aminopropyltrimethoxysilane films by the use of a 172 nm excimer lamp under different irradiation conditions is described and completed by micropatterning experiments. The presence of 1000-5000 ppm oxygen was found to promote the transformation process to an inorganic-like surface. The films obtained were analyzed by X-ray photoelectron spectroscopy, contact angle measurements and fluorescence microscopy after covalent attachment of a fluorescent dye to the remaining amino groups. Complementary, silver staining was used to visualize photopatterning.

Investigation of excimer laser ablation threshold of polymers using a microphone

Energy Technology Data Exchange (ETDEWEB)

Krueger, Joerg; Niino, Hiroyuki; Yabe, Akira

2002-09-30

KrF excimer laser ablation of polyethylene terephthalate (PET), polyimide (PI) and polycarbonate (PC) in air was studied by an in situ monitoring technique using a microphone. The microphone signal generated by a short acoustic pulse represented the etch rate of laser ablation depending on the laser fluence, i.e., the ablation 'strength'. From a linear relationship between the microphone output voltage and the laser fluence, the single-pulse ablation thresholds were found to be 30 mJ cm{sup -2} for PET, 37 mJ cm{sup -2} for PI and 51 mJ cm{sup -2} for PC (20-pulses threshold). The ablation thresholds of PET and PI were not influenced by the number of pulses per spot, while PC showed an incubation phenomenon. A microphone technique provides a simple method to determine the excimer laser ablation threshold of polymer films.

Polyfluorophore Excimers and Exciplexes as FRET Donors in DNA

Science.gov (United States)

Teo, Yin Nah; Kool, Eric T.

2009-01-01

We describe studies aimed at testing whether oligomeric exciplex- and excimer fluorophores conjugated to DNA have the potential to act as donors for energy transfer by the Förster mechanism. Oligodeoxyfluorosides (ODFs) are composed of stacked, electronically interacting fluorophores replacing the bases on a DNA scaffold. The monomer chromophores in the twenty tetramer-length ODFs studied here include pyrene (Y), benzopyrene (B), perylene (E), dimethylaminostilbene (D), and a nonfluorescent spacer (S); these are conjugated in varied combinations at the 3’ end of a 14mer DNA probe sequence. In the absence of an acceptor chromophore, many of the ODF-DNAs show broad, unstructured long-wavelength emission peaks characteristic of excimer and exciplex excited states, similar to what has been observed for unconjugated ODFs. Although such delocalized excited states have been widely studied, we know of no prior report of their use in FRET. We tested the ability of the twenty ODFs to donate energy to Cy5 and TAMRA dyes conjugated to a complementary strand of DNA, with these acceptors oriented either at the near or far end of the ODF-conjugated probes. Results showed that a number of the ODF fluorophores exhibited relatively efficient energy transfer characteristic of the Förster mechanism, as judged by drops in donor emission quantum yield and fluorescence lifetime, accompanied by increases in intensity of acceptor emission bands. Excimer/exciplex bands in the donors were selectively quenched while shorter-wavelength monomer emission stayed relatively constant, consistent with the notion that the delocalized excited states, rather than individual fluorophores, are the donors. Interestingly, only specific sequences of ODFs were able to act as donors, while others did not, even though their emission wavelengths were similar. The new FRET donors possess large Stokes shifts, which can be beneficial for multiple applications. In addition, all ODFs can be excited at a single

[The 308 nm Excimer laser for the treatment of psoriasis and inflammatory skin diseases].

Science.gov (United States)

Fritz, K; Salavastru, C

2018-01-01

Overall, the 308 nm Excimer laser enables not only a more effective and safer UVB therapy than classical UV phototherapy, but also targeted irradiation in higher doses with a lower cumulative load, which results in faster healing of mainly circumscribed skin changes. This also applies to therapy-resistant residual lesions which, despite systemic therapy, did not diminish. Combination therapies usually improve the result and enable the dose of UVB and systemic medication to be reduced. Excimer laser therapy can be used for an increasing number of skin diseases, especially those that respond to phototherapy or photochemotherapy.

Refractive microlenses produced by excimer laser machining of poly(methyl methacrylate)

DEFF Research Database (Denmark)

Jensen, Martin Frøhling; Krühne, Ulrich; H., L.

2005-01-01

A method has been developed whereby refractive microlenses can be produced in poly (methyl methacrylate) by excimer laser irradiation at λ = 248 nm. The lenses are formed by a combined photochemical and thermal process. The lenses are formed as depressions in the substrate material (negative foca...

[Indomethacin (indocollyre) versus diclofenac (voltarene) for the control of pain following excimer photoablation].

Science.gov (United States)

Cochener, B; Kling, F; Savary-Le Floch, G; Colin, J

2000-06-01

To compare effect of two topical non steroidal anti-inflammatory (NSAI) drugs: Indomethacin (Indocollyre)0.1 %, Chauvin Inc.) and Diclofenac (Voltaren 0.1%, Cibavision) on postoperative pain and epithelial regrowth following surface excimer photoablation. Eighty-six excimer operated patients, were divided in two similar groups depending on the NSAI instilled postoperatively and for 3 days (4 drops daily). No patient was informed of any other available drug. Pain intensity was quantified between 1 and 10 according to an analog scale (reported from 1 to 10 hours, then 4 times a day during 7 days). Complementary medications and functional symptoms were also notified. Biomicroscopic evaluation using fluorescein test was performed to assess reepithelialization. In term of pain, no significative difference was observed between the two groups concerning intensity, associated medications, or numbers of days of discomfort. Controversially, retreated eyes might induce more pain than initial treatments. No delay in epithelial regrowth was noted and the difference between the two groups in functional complaints was no statistically significant. Pain appears to be not related to ablation depth. DISCUSSION- CONCLUSION: Our results are correlated to literature reported data. Introduction of NSAI constitutes a real advent in the care of excimer postoperative pain. Effect of indomethacin seems comparable to diclofenac effect, but might be of interest because of no anesthetic property that might guarantee of no delay in wound healing response.

193nm high power lasers for the wide bandgap material processing

Science.gov (United States)

Fujimoto, Junichi; Kobayashi, Masakazu; Kakizaki, Koji; Oizumi, Hiroaki; Mimura, Toshio; Matsunaga, Takashi; Mizoguchi, Hakaru

2017-02-01

Recently infrared laser has faced resolution limit of finer micromachining requirement on especially semiconductor packaging like Fan-Out Wafer Level Package (FO-WLP) and Through Glass Via hole (TGV) which are hard to process with less defect. In this study, we investigated ablation rate with deep ultra violet excimer laser to explore its possibilities of micromachining on organic and glass interposers. These results were observed with a laser microscopy and Scanning Electron Microscope (SEM). As the ablation rates of both materials were quite affordable value, excimer laser is expected to be put in practical use for mass production.

Clinical results of PRK touch-up using Chiron/Technolas Keracor 116 excimer laser

Science.gov (United States)

Davidian, Mary E.; Keates, Richard H.; Ren, Qiushi

1995-05-01

Regression of effect as well as undercorrection are well established complications of excimer photorefractive keratectomy for the correction of myopia. In thirteen eyes initially treated with the VISX Taunton excimer laser and then retreated with the Chiron Technolas laser, the minimum follow-up time was six months. The mean postoperative refraction at six months was -0.442 +/- 0.996 D (diopters), significantly different from the pretreatment mean of -1.904 +/- 1.297 D. At six months after retreatment (10/13 eyes) 76.9% had an uncorrected visual acuity greater than or equal to 20/40 and (10/13 eyes) 76.9% were within 1 diopter of emmetropia. Only one eye had a significant increase in postoperative haze. The results of this study indicate that the majority of photorefractive keratectomy regressions and undercorrections can be successfully retreated.

Collisional and radiative processes in high-pressure discharge plasmas

Science.gov (United States)

Becker, Kurt H.; Kurunczi, Peter F.; Schoenbach, Karl H.

2002-05-01

Discharge plasmas at high pressures (up to and exceeding atmospheric pressure), where single collision conditions no longer prevail, provide a fertile environment for the experimental study of collisions and radiative processes dominated by (i) step-wise processes, i.e., the excitation of an already excited atomic/molecular state and by (ii) three-body collisions leading, for instance, to the formation of excimers. The dominance of collisional and radiative processes beyond binary collisions involving ground-state atoms and molecules in such environments allows for many interesting applications of high-pressure plasmas such as high power lasers, opening switches, novel plasma processing applications and sputtering, absorbers and reflectors for electromagnetic waves, remediation of pollutants and waste streams, and excimer lamps and other noncoherent vacuum-ultraviolet light sources. Here recent progress is summarized in the use of hollow cathode discharge devices with hole dimensions in the range 0.1-0.5 mm for the generation of vacuum-ultraviolet light.

Nebulae at keratoconus--the result after excimer laser removal.

Science.gov (United States)

Fagerholm, P; Fitzsimmons, T; Ohman, L; Orndahl, M

1993-12-01

Ten patients underwent excimer laser ablation due to nebula formation at keratoconus. The nebulae interfered significantly with contact lens fit or wearing time. The mean follow-up time in these patients was 16.5 months. Following surgery all patients could be successfully fitted with a contact lens and thereby obtain good visual acuity. Furthermore, contact lens wearing time was 8 hours or more in all cases. In 2 patients the nebulae recurred but were successfully retreated.

Excimer laser assisted re-oxidation of BaTiO3 thin films on Ni metal foils

International Nuclear Information System (INIS)

Bharadwaja, S. S. N.; Ko, S. W.; Qu, W.; Clark, T.; Rajashekhar, A.; Motyka, M.; Podraza, N.; Randall, C. A.; Trolier-McKinstry, S.

2016-01-01

Excimer laser assisted re-oxidation for reduced, crystallized BaTiO 3 thin films on Ni-foils was investigated. It was found that the BaTiO 3 can be re-oxidized at an oxygen partial pressure of ∼50 mTorr and substrate temperature of 350 °C without forming a NiO x interface layer between the film and base metal foil. The dielectric permittivity of re-oxidized films was >1000 with loss tangent values <2% at 100 Hz, 30 mV rms excitation signal. Electron Energy Loss Spectroscopy indicated that BaTiO 3 thin films can be re-oxidized to an oxygen stoichiometry close to ∼3 (e.g., stoichiometric). High resolution cross sectional transmission electron microscopy showed no evidence of NiO x formation between the BaTiO 3 and the Ni foil upon excimer laser re-oxidation. Spectroscopic ellipsometry studies on laser re-oxidized [001] C and [111] C BaTiO 3 single crystals indicate that the re-oxidation of BaTiO 3 single crystals is augmented by photo-excitation of the ozone, as well as laser pulse induced temperature and local stress gradients

Composition of the excimer laser-induced plume produced during LASIK refractive surgery

Science.gov (United States)

Glickman, Randolph D.; Liu, Yun; Mayo, George L.; Baribeau, Alan D.; Starck, Tomy; Bankhead, Tom

2003-07-01

Because of concerns about potential hazards to surgical personnel of the plume associated with laser refractive surgery, this study was performed to characterize the composition of such plumes. Filter elements were removed from the smoke evacuator of a VISX S3 excimer laser (filter pore size ~0.3 microns) and from a Mastel Clean Room ( filter pore size ~0.2 microns) used with a LADARVISION excimer laser. The filters from both laser systems captured the laser-induced plumes from multiple, routine, LASIK patient procedures. Some filters were processed for scanning electron microscopy, while others were extracted with methanol and chloroform for biochemical analysis. Both the VISX "Final Air" filter and the Mastel "Clean Room" filter captured material that was not observed in filters that had clean operating room air only passed through them. In the VISX system, air flows through the filter unit parallel to the filter matrix. SEM analysis showed these filters captured discrete particles of 0.3 to 3.0 microns in size. In the Mastel Clean Room unit, air flows orthogonally through the filter, and the filter matrix was heavily layered with captured debris so that individual particles were not readily distinguished. Amino acid analysis and gel electrophoresis of extracted material revealed proteinaceous molecules as large as 5000 molecular weight. Such large molecules in the laser plume are not predicted by the existing theory of photochemical ablation. The presence of relatively large biomolecules may constitute a risk of allergenic reactions in personnel exposed to the plume, and also calls into question the precise mechanism of excimer laser photochemical ablation. Supported by the RMG Research Endowment, and Research to Prevent Blindness

Measurements of barium photocathode quantum yields at four excimer laser wavelengths

International Nuclear Information System (INIS)

Van Loy, M.D.; Young, A.T.; Leung, K.N.

1992-06-01

The electron quantum yields from barium cathodes excited by excimer laser radiation at 193, 248, 308, and 351 nm have been determined. Experiments with different cathode surface preparation techniques reveal that deposition of barium film a few microns thick on a clean copper surface under moderate vacuum conditions achieves relatively high quantum efficiencies. Quantum yields measured from surfaces prepared in this manner are 2.3 x 10 -3 at 193 nm, 7.6 x 10 - 4 at 248 nm, 6.1 x 10 -4 at 308 nm, and 4.0 x 10 -4 at 351 nm. Other preparation techniques, such as laser cleaning of a solid barium surface, produced quantum yields that were at least an order of magnitude lower than these values

Corneal ablation depth readout of the MEL 80 excimer laser compared to Artemis three-dimensional very high-frequency digital ultrasound stromal measurements.

Science.gov (United States)

Reinstein, Dan Z; Archer, Timothy J; Gobbe, Marine

2010-12-01

To evaluate the accuracy of the ablation depth readout for the MEL 80 excimer laser (Carl Zeiss Meditec). Artemis 1 very high-frequency digital ultrasound measurements were obtained before and at least 3 months after LASIK in 121 eyes (65 patients). The Artemis-measured ablation depth was calculated as the maximum difference in stromal thickness before and after treatment. Laser in situ keratomileusis was performed using the MEL 80 excimer laser and the Hansatome microkeratome (Bausch & Lomb). The Aberration Smart Ablation profile was used in 56 eyes and the Tissue Saving Ablation profile was used in 65 eyes. All ablations were centered on the corneal vertex. Comparative statistics and linear regression analysis were performed between the laser readout ablation depth and Artemis-measured ablation depth. The mean maximum myopic meridian was -6.66±2.40 diopters (D) (range: -1.50 to -10.00 D) for Aberration Smart Ablation-treated eyes and -6.50±2.56 D (range: -1.34 to -11.50 D) for Tissue Saving Ablation-treated eyes. The MEL 80 readout was found to overestimate the Artemis-measured ablation depth by 20±12 μm for Aberration Smart Ablation and by 21±12 μm for Tissue Saving Ablation profiles. The accuracy of ablation depth measurement was improved by using the Artemis stromal thickness profile measurements before and after surgery to exclude epithelial changes. The MEL 80 readout was found to overestimate the achieved ablation depth. The linear regression equations could be used by MEL 80 users to adjust the ablation depth for predicted residual stromal thickness calculations without increasing the risk of ectasia due to excessive keratectomy depth as long as a suitable flap thickness bias is included. Copyright 2010, SLACK Incorporated.

Excimer laser beam profile recording based on electrochemical etched polycarbonate

International Nuclear Information System (INIS)

Parvin, P.; Jaleh, B.; Zangeneh, H.R.; Zamanipour, Z.; Davoud-Abadi, Gh.R.

2008-01-01

There is no polymeric detector used to register the beam profile of UV lasers. Here, a method is proposed for the measurement of intensive UV beam pattern of the excimer lasers based on the photoablated polycarbonate detector after coherent UV exposure and the subsequent electrochemical etching. UV laser induced defects in the form of self-microstructuring on polycarbonate are developed to replicate the spatial intensity distribution as a beam profiler

Excimer laser beam profile recording based on electrochemical etched polycarbonate

Energy Technology Data Exchange (ETDEWEB)

Parvin, P. [Physics Department, Amirkabir University of Technology, P.O. Box 15875-4413, Hafez Ave, Tehran (Iran, Islamic Republic of); Laser Research Center, AEOI, P.O. Box 1165-8486, Tehran (Iran, Islamic Republic of)], E-mail: parvin@aut.ac.ir; Jaleh, B. [Physics Department, Bu-Ali Sina University, Postal Code 65174, Hamedan (Iran, Islamic Republic of); Zangeneh, H.R. [Physics Department, Amirkabir University of Technology, P.O. Box 15875-4413, Hafez Ave, Tehran (Iran, Islamic Republic of); Zamanipour, Z. [Laser Research Center, AEOI, P.O. Box 1165-8486, Tehran (Iran, Islamic Republic of); Davoud-Abadi, Gh.R. [Physics Department, Amirkabir University of Technology, P.O. Box 15875-4413, Hafez Ave, Tehran (Iran, Islamic Republic of)

2008-08-15

There is no polymeric detector used to register the beam profile of UV lasers. Here, a method is proposed for the measurement of intensive UV beam pattern of the excimer lasers based on the photoablated polycarbonate detector after coherent UV exposure and the subsequent electrochemical etching. UV laser induced defects in the form of self-microstructuring on polycarbonate are developed to replicate the spatial intensity distribution as a beam profiler.

Perspectives and advantages of the use of excimer laser annealing for MOS technology

International Nuclear Information System (INIS)

Privitera, V.; Alippi, P.; Camalleri, M.

2006-01-01

The integration of excimer laser annealing (ELA) into the MOS device technology has been studied and evaluated within the frame of the IST project FLASH (Fundamentals and applications of laser processing for highly innovative MOS technology), funded by the European Commission. The final aim of the project was to demonstrate that ELA can be applied as a reliable, effective and advantageous process in the context of semiconductor device fabrication. Some of the results of this activity are summarised, relative to the experimental characterization and theoretical modelling. The electrical characterization of the transistor fabricated by ELA is also presented, showing a device yield of 90% on wafer

Four-year to seven-year outcomes of advanced surface ablation with excimer laser for high myopia.

Science.gov (United States)

Hansen, Rasmus Søgaard; Lyhne, Niels; Grauslund, Jakob; Grønbech, Keea Treu; Vestergaard, Anders Højslet

2015-07-01

We aimed to evaluate and compare outcomes after photorefractive keratectomy with cooling (cPRK) and laser-assisted subepithelial keratectomy (LASEK) for high myopia. This was a retrospective, single-masked follow-up study of patients treated for myopia between 2007 and 2009 with cPRK or LASEK, using a high-frequency flying-spot excimer laser with eye-tracker (MEL80; Carl Zeiss, Jena, Germany). One eye of each patient was randomly chosen for analysis. Re-treated eyes were excluded. Forty-six cPRK patients and 35 LASEK patients were included. Spherical equivalent averaged -7.69 ± 1.47 diopters (D) in cPRK eyes and -7.98 ± 2.06 D in LASEK eyes (p = 0.31) before surgery. The average follow-up time was 4.6 years in cPRK patients and 6.0 years in LASEK patients (p < 0.05). At final follow-up, no cPRK eyes and one LASEK eye (p = 0.46) had lost two lines of corrected distance visual acuity (CDVA). No eyes had significant haze at final follow-up, although trace haze was found in four cPRK eyes and six LASEK eyes (p = 0.44). However, at 6 weeks after surgery, zero cPRK eyes and nine LASEK eyes (p < 0.05) had significant haze. At final follow-up, 63 % of cPRK eyes and 35 % of LASEK eyes (p = 0.17) were within ±1.0 D of intended refraction. Finally, 100 % of cPRK patients and 92 % of LASEK patients (p = 0.87) were satisfied or very satisfied with the surgery at final follow-up. cPRK and LASEK seemed safe and with high patient satisfaction 4 to 7 years after surgery for high myopia. However, cPRK was more effective than LASEK in reducing initial significant corneal haze.

Fabrication of biosynthetic vascular prostheses by 193-nm excimer laser radiation

Science.gov (United States)

Husinsky, Wolfgang; Csek, Ch.; Bartel, A.; Grabenwoeger, M.; Fitzal, F.; Wolner, Ernst

1998-05-01

This study was undertaken to investigate the feasibility of transmural capillary ingrowth into the inner surface of biosynthetic vascular prostheses (OmniflowTM) through perforations created by an excimer-laser, thus inducing an endothelial cell coverage. The biosynthetic vascular prostheses (10 cm length, 6 mm (phi) ) were perforated with an excimer laser ((phi) of the holes 50 - 100 micrometer, distance 4 mm) and implanted into the carotid arteries of 8 sheep. The laser tissue interaction process of 193 nm radiation ensures minimal thermal damage to the prostheses. They were compared to untreated OmniflowTM prostheses implanted at the contralateral side. Three months after implantation the prostheses were explanted and evaluated by gross morphology, histological examination and scanning electron microscopy. Scanning electron microscopy showed endothelial cells in the midgraft portion of all perforated prostheses, whereas collagen fibers, fibrin meshwork and activated platelets formed the inner layer in 6 out of 8 untreated OmniflowTM prostheses. It can be concluded, that spontaneous endothelialization of biosynthetic vascular prostheses can be achieved by transmural capillary ingrowth through perforations in the wall of the prostheses in an experimental sheep model.

Random noise can help to improve synchronization of excimer laser pulses.

Science.gov (United States)

Mingesz, Róbert; Barna, Angéla; Gingl, Zoltán; Mellár, János

2016-02-01

Recently, we have reported on a compact microcontroller-based unit developed to accurately synchronize excimer laser pulses (Mingesz et al. 2012 Fluct. Noise Lett. 11, 1240007 (doi:10.1142/S021947751240007X)). We have shown that dithering based on random jitter noise plus pseudorandom numbers can be used in the digital control system to radically reduce the long-term drift of the laser pulse from the trigger and to improve the accuracy of the synchronization. In this update paper, we present our new experimental results obtained by the use of the delay-controller unit to tune the timing of a KrF excimer laser as an addition to our previous numerical simulation results. The hardware was interfaced to the laser using optical signal paths in order to reduce sensitivity to electromagnetic interference and the control algorithm tested by simulations was applied in the experiments. We have found that the system is able to reduce the delay uncertainty very close to the theoretical limit and performs well in real applications. The simple, compact and flexible system is universal enough to also be used in various multidisciplinary applications.

FEM for modelling 193 nm excimer laser treatment of SiO{sub 2}/Si/Si{sub (1-x)}Ge{sub x} heterostructures on SOI substrates

Energy Technology Data Exchange (ETDEWEB)

Conde, J.C.; Chiussi, S.; Gontad, F.; Gonzalez, P. [Dpto. Fisica Aplicada, E.T.S.I.I. University of Vigo, Campus Universitario, Rua Maxwell s/n, 36310 Vigo (Spain); Martin, E. [Dpto. de Mecanica, Maquinas, Motores Termicos y Fluidos, E.T.S.I.I. University of Vigo, Campus Universitario, Rua Maxwell s/n, 36310 Vigo (Spain)

2011-03-15

Research on epitaxial crystalline silicon (c-Si) and silicon-germanium (Si{sub 1-x}Ge{sub x}) alloys growth and annealing for microelectronic purposes, such as Micro- or Nano-Electro-Mechanical Systems (MEMS or NEMS) and Silicon-On-Nothing (SON) devices is continuously in progress. Laser assisted annealing techniques using commercial ArF Excimer Laser sources are based on ultra-rapid heating and cooling cycles induced by the 193 nm pulses of 20 ns, which are absorbed in the near surface region of the heterostructures. During and after the absorption of these laser pulses, complex physical processes appear that strongly depend on sample structure and applied laser pulse energy densities. The control of the experimental parameters is therefore a key task for obtaining high quality alloys. The Finite ElementsMethod (FEM) is a powerful tool for the optimization of such treatments, because it provides the spatial and temporal temperature fields that are produced by the laser pulses. In this work, we have used a FEM commercial software, to predict the temperatures gradients induced by ArF excimer laser over a wide energy densities range, 0.1<{phi}<0.4 J/cm{sup 2}, on different SiO{sub 2}/Si/Si{sub (1-x)}Ge{sub (x)} thin films deposited on SOI substrate. These numerical results allow us to predict the threshold energies needed to reach the melting point (MP) of the Si and SiGe alloy without oxidation of the thin films system. Therefore, it is possible to optimize the conditions to achieve high quality epitaxy films. (copyright 2011 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

Excimer laser decomposition of silicone

International Nuclear Information System (INIS)

Laude, L.D.; Cochrane, C.; Dicara, Cl.; Dupas-Bruzek, C.; Kolev, K.

2003-01-01

Excimer laser irradiation of silicone foils is shown in this work to induce decomposition, ablation and activation of such materials. Thin (100 μm) laminated silicone foils are irradiated at 248 nm as a function of impacting laser fluence and number of pulsed irradiations at 1 s intervals. Above a threshold fluence of 0.7 J/cm 2 , material starts decomposing. At higher fluences, this decomposition develops and gives rise to (i) swelling of the irradiated surface and then (ii) emission of matter (ablation) at a rate that is not proportioned to the number of pulses. Taking into consideration the polymer structure and the foil lamination process, these results help defining the phenomenology of silicone ablation. The polymer decomposition results in two parts: one which is organic and volatile, and another part which is inorganic and remains, forming an ever thickening screen to light penetration as the number of light pulses increases. A mathematical model is developed that accounts successfully for this physical screening effect

Semiconductor processing with excimer lasers

International Nuclear Information System (INIS)

Young, R.T.; Narayan, J.; Christie, W.H.; van der Leeden, G.A.; Rothe, D.E.; Cheng, L.J.

1983-01-01

The advantages of pulsed excimer lasers for semiconductor processing are reviewed. Extensive comparisons of the quality of annealing of ion-implanted Si obtained with XeCl and ruby lasers have been made. The results indicate that irrespective of the large differences in the optical properties of Si at uv and visible wavelengths, the efficiency of usage of the incident energy for annealing is comparable for the two lasers. However, because of the excellent optical beam quality, the XeCl laser can provide superior control of the surface melting and the resulting junction depth. Furthermore, the concentrations of electrically active point defects in the XeCl laser annealed region are 2 to 3 orders of magnitude lower than that obtained from ruby or Nd:YAG lasers. All these results seem to suggest that XeCl lasers should be suitable for fabricating not only solar cells but also the more advanced device structures required for VLSI or VHSIC applications

Original papers A study on efficacy of 308 nm excimer light therapy in alopecia areata

Directory of Open Access Journals (Sweden)

Zo Nun Sanga

2015-06-01

Full Text Available Introduction. Alopecia areata (AA is an autoimmune condition characterized by T-cell-mediated attack on hair follicles. Objective. Evaluation of efficacy of 308 nm excimer light in the treatment of alopecia areata. Material and methods. Patches of AA were treated twice weekly, but not on 2 consecutive days, with UVB excimer 308 nm light. In all patients, half of the AA patch was irradiated and the other half was spared, covered with a black rubber shield and taken as a control. Therapy was started with an initial dose of 300 mJ/cm 2 , with an incremental dose of 100 mJ/cm 2 at every sitting until fine erythema appeared. Results. At the end of the treatment, one patient (3.33% at the test site showed > 50% hair regrowth vs. none at the control site. After a 2-month post-treatment period, successful hair regrowth (grades 3 and 4 was seen in 12 patients at test sites and in 2 patients at control sites. The differences were statistically significant (p < 0.05. After 4 months successful hair regrowth (grades 3 and 4 was seen in 16 patients at test sites and in 5 patients at control sites. The differences were statistically significant (p 0.05. Conclusions. Excimer light has the potential to stimulate hair regrowth in patches of alopecia areata.

Studies of free radicals by ultraviolet excimer laser photolysis. Progress report, 1 April 1980-1 November 1980

International Nuclear Information System (INIS)

Leone, S.R.

1980-01-01

An experimental technique has been developed to produce and directly study vibrationally excited free radicals. Pulses of light from an ultraviolet excimer laser are used to photodissociate small molecules to generate free radicals with high internal excitation. The radicals are detected directly by the technique of time and wavelength-resolved infrared emission spectroscopy using a background-limited copper-doped germanium infrared detector. New results have been obtained on the CH 3 radical. A complete spectrum of the CH 3 umbrella band reveals for the first time accurate positions of the vibrational progression in this band. Photofragmentation of (CH 3 ) 2 Hg has yielded detailed information on the vibrational distribution, rotational temperature, and deactivation rates of the CH 3 stretch mode. A technique to study chemical chain reactions using low power, radical-specific, laser initiation and realtime kinetics detection had previously been demonstrated. The results provide a general method to study a large number of chain reaction combustion systems in greater detail. New results on more complex chain reactions such as Cl 2 /butane reveal that highly detailed infrared emission spectra of various products of the chain and their time evolution is possible. Partitioning of energy between vibrational degrees of freedom and translational heating is obtained over the course of the combustion

Surface morphologies of excimer-laser annealed BF2+ implanted Si diodes

International Nuclear Information System (INIS)

Burtsev, A.; Schut, H.; Nanver, L.K.; Veen, A. van; Slabbekoorn, J.; Scholtes, T.L.M.

2004-01-01

Laser-induced surface roughness and damage formation in ultra-shallow n + -p and p + -n junctions, formed by low energy (5 keV) As + and BF 2 + implantations in Si, respectively, with a dose of 1 x 10 15 cm -2 have been investigated by atomic force microscopy (AFM) and Positron Annihilation Doppler Broadening (PADB) technique. The Si surface roughness is found to increase with laser energy density, and reaches a value of 3.5 nm after excimer-laser annealing (ELA) at 1100 mJ/cm 2 . However, anomalous behavior is witnessed for BF 2 + -implanted Si sample at 800 mJ/cm 2 , at which energy very high surface protrusions up to 9 nm high are observed. By PADB this behavior is correlated to extensive deep microcavity formation in the Si whereby the volatile F 2 fraction can accumulate and evaporate/out-diffuse, leading to Si surface roughening. The consequences for the diode characteristics and contact resistivity are examined

Excimer-laser-induced activation of Mg-doped GaN layers

International Nuclear Information System (INIS)

Lin, Y.-J.; Liu, W.-F.; Lee, C.-T.

2004-01-01

In this study, we investigated the 248 nm excimer-laser-induced activation of the Mg-doped GaN layers. According to the observed photoluminescence results and the x-ray photoelectron spectroscopy measurements, we found that the dissociation of the Mg-H complexes and the formation of hydrogenated Ga vacancies (i.e., V Ga H 2 ) and/or the Ga vacancies occupied by interstitial Mg during the laser irradiation process, led to an increase in the hole concentration

Hg{sup 2+}-induced self-assembly of a naphthalimide derivative by selective 'turn-on' monomer/excimer emissions

Energy Technology Data Exchange (ETDEWEB)

Wanichacheva, Nantanit, E-mail: wanichacheva.nantanit@gmail.com [Department of Chemistry, Faculty of Science, Silpakorn University, Nakorn Pathom 73000 (Thailand); Prapawattanapol, Narupon [Petrochemistry and Polymer Science Program, Faculty of Science, Chulalongkorn University, Bangkok 10330 (Thailand); Sanghiran Lee, Vannajan [Department of Chemistry, Faculty of Science, University of Malaya 50603, Kuala Lumpur (Malaysia); Grudpan, Kate [Department of Chemistry, Center for Innovation in Chemistry, Faculty of Science, and Center of Excellence in Innovation for Analytical Science and Technology, Chiang Mai 50200 (Thailand); Petsom, Amorn [Research Centre for Bioorganic Chemistry, Department of Chemistry, Faculty of Science, Chulalongkorn University, Bangkok 10330 (Thailand)

2013-02-15

A novel fluorescent sensor bearing two naphthalimide fluorophores based on 2-(3-(2-aminoethylsulfanyl)propylsulfanyl)ethanamine, 1, was readily synthesized for the recognition of Hg{sup 2+}. The sensitive and selective binding behaviors of 1 were investigated by fluorescence spectroscopy. Sensor 1 selectively binds Hg{sup 2+} by exhibiting OFF-ON fluorescence enhancement behaviors of the monomer and excimer bands. The sensor provides excellent Hg{sup 2+}-selectivity in the presence of high concentrations of competitive ions, particularly Cu{sup 2+} and Pb{sup 2+} as well as Na{sup +}, K{sup +}, Mn{sup 2+}, Cd{sup 2+}, Ni{sup 2+}, Ca{sup 2+}, Li{sup +}, Zn{sup 2+} and Co{sup 2+}, with an available detection limit of 2.1 Multiplication-Sign 10{sup -7} M or 42 ppb. - Highlights: Black-Right-Pointing-Pointer Multidentate sulfide-containing ligand bounded to naphthalimide as new Hg{sup 2+} sensor. Black-Right-Pointing-Pointer Sensor is prepared by a straightforward two-step synthesis. Black-Right-Pointing-Pointer Sensor shows high sensitivity and selectivity to Hg{sup 2+} with detection limit of 42 ppb. Black-Right-Pointing-Pointer Hg{sup 2+}-binding is indicated by fluorescence enhancement Black-Right-Pointing-Pointer Sensor 'turns-on' both monomeric and excimer emissions by the addition of Hg{sup 2+}.

LASIK for myopia and astigmatism using the SCHWIND AMARIS excimer laser: an international multicenter trial.

Science.gov (United States)

Arbelaez, Maria Clara; Aslanides, Ioannis M; Barraquer, Carmen; Carones, Francesco; Feuermannova, Alena; Neuhann, Tobias; Rozsival, Pavel

2010-02-01

To assess the efficacy, predictability, and safety of LASIK for the surgical correction of low to moderate myopia with astigmatism using the SCHWIND AMARIS excimer laser. Six international study sites enrolled 358 eyes with a manifest refraction spherical equivalent (MRSE) from -0.50 to -7.38 diopters (D) (mean sphere: -3.13+/-1.58 D) with up to -5.00 D of astigmatism (mean: -0.69+/-0.67 D). All eyes underwent treatment with the nonwavefront-guided aspheric algorithm of the SCHWIND AMARIS excimer laser. All eyes were targeted for emmetropia. Refractive outcomes and corneal higher order aberrations were analyzed pre- and postoperatively. Visual quality was assessed using photopic and mesopic contrast sensitivity. Six-month postoperative outcomes are reported. At 6 months postoperative, the MRSE for all eyes was -0.21+/-0.20 D, and 96% (343/358) of eyes had MRSE within +/-0.50 D. Uncorrected visual acuity was 20/20 or better in 98% (351/358) of eyes, and no eyes lost 2 or more lines of best spectacle-corrected visual acuity. The total corneal higher order aberrations root-mean-square increased by 0.09 microm, spherical aberration increased by 0.08 microm, and coma increased by 0.04 microm postoperatively. Photopic and mesopic contrast sensitivity did not change 6 months postoperatively. Treatment of myopia with astigmatism using the SCHWIND AMARIS excimer laser is safe, efficacious, predictable, and maintains visual quality.

Comparative study of efficacy of excimer light therapy vs. intralesional triamcinolone vs. topical 5% minoxidil for alopecia areata: an observational study

Directory of Open Access Journals (Sweden)

Zo Nun Sanga

2015-06-01

Full Text Available Introduction. Alopecia areata (AA is a chronic inflammatory disease that involves hair follicles, and sometimes nails, caused by a T-cell mediated autoimmune mechanism. Current treatment modalities include corticosteroids (oral, topical or intralesional, minoxidil, contact sensitizers (DNCB, DPCP and SADBE, immunosuppressants (methotrexate or azathioprine, DMARDs (sulfasalazine, and phototherapy. Objective. To compare the efficacy of excimer light therapy, intralesional triamcinolone and 5% topical minoxidil. Material and methods. After taking consent, 40 patients were treated with excimer light, 46 patients with intralesional triamcinolone injection and 14 patients with 5% topical minoxidil. The results were compared by their photographs taken prior to treatment, at 2 months and 6 months of follow-up. Results. Among the excimer group, 21/32 (61.76% patients with a single patch and 1/6 (16.67% with multiple patches achieved > 50% hair regrowth. In the triamcinolone group, 23/30 (76.67% with a single patch and 10/16 (62.5% with multiple patches achieved > 50% hair regrowth, and in the minoxidil group, 4/12 (33.33% with a single patch and none, i.e. 0/2, with multiple patches achieved > 50% regrowth. Conclusions. After comparing the efficacy of excimer light therapy, intralesional triamcinolone and 5% minoxidil, it was concluded that intralesional triamcinolone seems to be the most efficacious. Multiple AA patches were more resistant than a single patch. Scalp response was much better than beard.

Excimer laser processing of inkjet-printed and sputter-deposited transparent conducting SnO2:Sb for flexible electronics

International Nuclear Information System (INIS)

Cranton, Wayne M.; Wilson, Sharron L.; Ranson, Robert; Koutsogeorgis, Demosthenes C.; Chi Kuangnan; Hedgley, Richard; Scott, John; Lipiec, Stephen; Spiller, Andrew; Speakman, Stuart

2007-01-01

The feasibility of low-temperature fabrication of transparent electrode elements from thin films of antimony-doped tin oxide (SnO 2 :Sb, ATO) has been investigated via inkjet printing, rf magnetron sputtering and post-deposition excimer laser processing. Laser processing of thin films on both glass and plastic substrates was performed using a Lambda Physik 305i excimer laser, with fluences in the range 20-100 mJ cm -2 reducing sheet resistance from as-deposited values by up to 3 orders of magnitude. This is consistent with TEM analysis of the films that shows a densification of the upper 200 nm of laser-processed regions

Micro flow-through PCR in a PMMA chip fabricated by KrF excimer laser.

Science.gov (United States)

Yao, Liying; Liu, Baoan; Chen, Tao; Liu, Shibing; Zuo, Tiechuan

2005-09-01

As the third PCR technology, micro flow-through PCR chip can amplify DNA specifically in an exponential fashion in vitro. Nowadays many academies in the world have successfully amplified DNA using their own-made flow-through PCR chip. In this paper, the ablation principle of PMMA at 248 nm excimer laser was studied, then a PMMA based flow-through PCR chip with 20 cycles was fabricated by excimer laser at 19 kv and 18 mm/min. The chip was bonded together with another cover chip at 105( composite function)C, 160 N and 20 minutes. In the end, it was integrated with electrical thermal thin films and Pt 100 temperature sensors. The temperature controllers was built standard PID digital temperature controller, the temperature control precision was +/- 0.2( composite function)C. The temperature grads between the three temperature zones were 16.5 and 22.2( composite function)C respectively, the gaps between the temperature zones could realize heat insulation.

A pulsed electron injector using a metal photocathode irradiated by an excimer laser

International Nuclear Information System (INIS)

Kauppila, T.J.; Builta, L.A.; Crutcher, J.K.; Elliott, J.C.; Moir, D.C.

1987-01-01

The hot cathode of an electron gun is replaced by a metallic photocathode driven by an excimer laser. The current, current density, and emittance of the 500-kV electron beam produced by the photoelectron source are presented. In addition, the temperature of the photocathode is varied to study the possibility of a hybrid source

excimer laser

Indian Academy of Sciences (India)

This gas then passes through a set of water-cooled aluminum finned tube heat exchangers. ... been made leak tight better than 10. −5 ... The excitation circuit primarily consists of a high voltage power supply, a thyratron (CX 3608). Figure 4.

Excimer laser processing of Ti-6Al-4V

International Nuclear Information System (INIS)

Folkes, J.A.; Shibata, K.

1994-01-01

The effect of the excimer laser on the surface of Ti-6Al-4V is reported. Particular concentration is given to surface modification for potential materials processing applications. Results showed that: (1) there is an optimum energy for smoothing titanium; (2) at this energy density increasing the number of pulses has some, but not a significant, effect on the smoothing process; and (3) relatively smooth surfaces could be achieved at higher energy densities if the sample was processed in a helium atmosphere. Other typical surface modifications and features are also reported, including the effect of different gases on the process

The application of excimer lasers for corneal sculpturing

International Nuclear Information System (INIS)

King, M.C.

1990-01-01

Of the broad selection of lasers available for surgery, the argon fluoride excimer laser offers a set of attributes that make it uniquely suited for the removal of corneal tissue. With ultraviolet radiation at 193mm, the energy of an individual photon (6.3 electron volts) is sufficient to break bonds in protein molecules without generating molecular vibration (heat). A single laser pulse is capable of removing 0.25 microns of corneal tissue over a well defined area 80 mm 2 in extent. This excision with a lateral precision to a fraction of a micron causes no discernible damage to neighboring cells. The smooth surface left after the tissue is removed promotes a quick and predictable regrowth of the epithelium. The penetration of radiation into the underlying tissue is the order of a micron so there is no potential harm to the lens or retinal tissue. Insignificant mutagenesis or unscheduled DNA synthesis has been detected as a result of tissue irradiation at this wavelength. In the past few years major progress has been made towards developing ophthalmic procedures which utilize the unique properties of this laser. To date there are FDA IDE's (Investigational Device Exemptions) for the following procedures: Photorefractive Keratectomy (PRK) or corneal reshaping for correcting near-sightedness, far-sightedness and astigmatism without the need for eye glasses, contact lenses or conventional refractive surgery (Radial Keratotomy); Partial Excimer Trabeculectomy for relieving the pressure build-up caused by glaucoma; T-Excisons for reducing astigmatism; Myopic Keratomileusis (MKM) for the refractive correction of severe myopia; superficial Keratectomy (corneal smoothing) for treating various corneal scars, dystrophies, recurrent corneal erosion etc. In this paper the fundamentals of beam tissue interaction at 193nm will be discussed

Krypton excimer laser oscillation by discharge pumping

International Nuclear Information System (INIS)

Shirai, Takahiro; Tabe, Yoshitaka; Kubodera, Shoichi; Sasaki, Wataru; Kawanaka, Junji

2001-01-01

We have demonstrated vacuum ultraviolet (VUV) laser oscillation of the krypton excimer (Kr 2 *) excited by a compact self-sustained discharge device. We have observed a spectral narrowing of the Kr 2 * emission centered at 147.8 nm. A deconvoluted spectral width is 0.5 nm (FWHM), which reveals a contrast to a 13 nm spectral width of the spontaneous emission. The Kr 2 * intensity has increased one order of magnitude when a charging voltage was increased larger than 29 kV. The success of the lasing in the VUV spectral region has been attributed to the success of a stable glow discharge of Kr at 10 atm. The pulse width of the VUV laser radiation is 400 ns (FWHM). The maximum output energy measured is as large as 150 μJ. (author)

Excimer laser doping technique for application in an integrated CdTe imaging device

CERN Document Server

Mochizuki, D; Aoki, T; Tomita, Y; Nihashi, T; Hatanaka, Y

1999-01-01

CdTe is an attractive semiconductor material for applications in solid-state high-energy X-ray and gamma-ray imaging systems because of its high absorption coefficient, large band gap, good mobility lifetime product of holes and stability at normal atmospheric conditions. We propose a new concept for fabricating an integrated CdTe with monolithic circuit configuration for two-dimensional imaging systems suitable for medical, research or industrial applications and operation at room temperature. A new doping technique has been recently developed that employs excimer laser radiation to diffuse impurity atoms into the semiconductor. Accordingly, heavily doped n- and p-type layers with resistivities less than 1 OMEGA cm can be formed on the high resistive CdTe crystals. We have further extended this technique for doping with spatial pattern. We will present the laser doping technique and various results thus obtained. Spatially patterned doping is demonstrated and we propose the use of these doping techniques for...

Excimer laser coronary atherectomy in septal collaterals during retrograde recanalization of a chronic total occlusion

Directory of Open Access Journals (Sweden)

Bernward Lauer

2011-09-01

Full Text Available Management of chronic total occlusions has been refined through the development of a retrograde approach via collateral pathways. We describe the use of Excimer Laser Coronary Atherectomy in the septal collaterals. This appraoch was not yet described in the literature.

Numerical analysis of temperature profile and thermal-stress during excimer laser induced heteroepitaxial growth of patterned amorphous silicon and germanium bi-layers deposited on Si(100)

Energy Technology Data Exchange (ETDEWEB)

Conde, J.C., E-mail: jconde@uvigo.e [Dpto. Fisica Aplicada, E.T.S.I.I. University of Vigo, Campus Universitario, Rua Maxwell s/n, E-36310 Vigo (Spain); Martin, E. [Dpto. de Mecanica, Maquinas y Motores Termicos y Fluidos, E.T.S.I.I. University of Vigo, Campus Universitario, Rua Maxwell s/n, E-36310 Vigo (Spain); Gontad, F.; Chiussi, S. [Dpto. Fisica Aplicada, E.T.S.I.I. University of Vigo, Campus Universitario, Rua Maxwell s/n, E-36310 Vigo (Spain); Fornarini, L. [Enea-Frascati, Via Enrico Fermi 45, I-00044 Frascati (Roma) (Italy); Leon, B. [Dpto. Fisica Aplicada, E.T.S.I.I. University of Vigo, Campus Universitario, Rua Maxwell s/n, E-36310 Vigo (Spain)

2010-02-26

A Finite Element Method (FEM) study of the coupled thermal-stress during the heteroepitaxial growth induced by excimer laser radiation of patterned amorphous hydrogenated silicon (a-Si:H) and germanium (a-Ge:H) bi-layers deposited on a Si(100) wafer is presented. The ArF (193 nm) excimer laser provides high energy densities during very short laser pulse (20 ns) provoking, at the same time, melting and solidification phenomena in the range of several tenths of nanoseconds. These phenomena play an important role during the growth of heteroepitaxial SiGe structures characterized by high Ge concentration buried under a Si rich surface. In addition, the thermal-stresses that appear before the melting and after the solidification processes can also affect to the epitaxial growth of high quality SiGe alloys in these patterned structures and, in consequence, it is necessary to predict their effects. The aim of this work is to estimate the energy threshold and the corresponding thermal-stresses in the interfaces and the borders of these patterned structures.

Numerical analysis of temperature profile and thermal-stress during excimer laser induced heteroepitaxial growth of patterned amorphous silicon and germanium bi-layers deposited on Si(100)

International Nuclear Information System (INIS)

Conde, J.C.; Martin, E.; Gontad, F.; Chiussi, S.; Fornarini, L.; Leon, B.

2010-01-01

A Finite Element Method (FEM) study of the coupled thermal-stress during the heteroepitaxial growth induced by excimer laser radiation of patterned amorphous hydrogenated silicon (a-Si:H) and germanium (a-Ge:H) bi-layers deposited on a Si(100) wafer is presented. The ArF (193 nm) excimer laser provides high energy densities during very short laser pulse (20 ns) provoking, at the same time, melting and solidification phenomena in the range of several tenths of nanoseconds. These phenomena play an important role during the growth of heteroepitaxial SiGe structures characterized by high Ge concentration buried under a Si rich surface. In addition, the thermal-stresses that appear before the melting and after the solidification processes can also affect to the epitaxial growth of high quality SiGe alloys in these patterned structures and, in consequence, it is necessary to predict their effects. The aim of this work is to estimate the energy threshold and the corresponding thermal-stresses in the interfaces and the borders of these patterned structures.

Pustular Palmoplantar Psoriasis Successfully Treated with Nb-UVB Monochromatic Excimer Light: A Case-Report

Directory of Open Access Journals (Sweden)

Serena Gianfaldoni

2017-07-01

Full Text Available Barber’s palmoplantar pustulosis (PPP is a form of localised pustular psoriasis, affecting the palmar and plantar surfaces. It is a chronic disease, with a deep impact on the patients’ quality of life. The Authors discuss a case of Baber Psoriasis successfully treated with monochromatic excimer light.

Putative photoacoustic damage in skin induced by pulsed ArF excimer laser

Energy Technology Data Exchange (ETDEWEB)

Watanabe, S.; Flotte, T.J.; McAuliffe, D.J.; Jacques, S.L.

1988-05-01

Argon-fluoride excimer laser ablation of guinea pig stratum corneum causes deeper tissue damage than expected for thermal or photochemical mechanisms, suggesting that photoacoustic waves have a role in tissue damage. Laser irradiation (193 nm, 14-ns pulse) at two different radiant exposures, 62 and 156 mJ/cm2 per pulse, was used to ablate the 15-microns-thick stratum corneum of the skin. Light and electron microscopy of immediate biopsies demonstrated damage to fibroblasts as deep as 88 and 220 microns, respectively, below the ablation site. These depths are far in excess of the optical penetration depth of 193-nm light (1/e depth = 1.5 micron). The damage is unlikely to be due to a photochemical mechanism because (a) the photons will not penetrate to these depths, (b) it is a long distance for toxic photoproducts to diffuse, and (c) damage is proportional to laser pulse intensity and not the total dose that accumulates in the residual tissue; therefore, reciprocity does not hold. Damage due to a thermal mechanism is not expected because there is not sufficient energy deposited in the tissue to cause significant heating at such depths. The damage is most likely due to a photoacoustic mechanism because (a) photoacoustic waves can propagate deep into tissue, (b) the depth of damage increases with increasing laser pulse intensity rather than with increasing total residual energy, and (c) the effects are immediate. These effects should be considered in the evaluation of short pulse, high peak power laser-tissue interactions.

Comparative study of efficacy of excimer light therapy vs intralesional triamcinolone vs topical 5% minoxidil: an observational study

Directory of Open Access Journals (Sweden)

Zonunsanga

2015-01-01

Full Text Available Introduction: Alopecia Areota is a chronic inflammatory disease that involves hair follicles, and sometimes nails, caused by T-cell mediated autoimmune mechanism. Current treatment modalities includes corticosteroids (oral, topical or intralesional, Minoxidil, Contact sensitizers like DNCB, DPCP and SADBE, Immunosuppressants like Methotrexate or Azathioprine, DMARDs like Sulfasalazine, and Phototherapy. Materials and methods: After taking consent, 40 patients treated with excimer light, 46 patients treated with triamcinolone injection intralesionally and 14 patients treated with topical minoxidil 5% were compared by their photographs taken prior to treatments, at 2 months and 6 months follow up. Results: Among the excimer group, 21/32 (61.76% with single patch and 1/6 (16.67% with multiple patches achieved >50% hair regrowth. Among Triamcinolone group, 23/30 (76.67% with single patch and 10/16 (62.5% with multiple patches achieved >50% hair regrowth. Among the Minoxidil group, 4/12 (33.33% with single patch and none .i.e 0/2 with multiple patches achieved >50% regrowth. Conclusion: After comparing the efficacy of Excimer light therapy, intralesional triamcinolone and 5% Minoxidil, it was concluded that intralesional triamcinolone seems to be the most efficacious. Multiple patches were more resistant than single patch. Scalp response much better than beard.

Levels of interleukin-6 in tears before and after excimer laser treatment

OpenAIRE

Resan Mirko; Stanojević Ivan; Petković-Ćurčin Aleksandra; Pajić Bojan; Vojvodić Danilo

2015-01-01

Background/Aim. Immune response and consequent inflammatory process which originate on ocular surface after a trauma are mediated by cytokines. Photoablation of corneal stroma performed by excimer laser causes surgically induced trauma. Interleukin-6 (IL-6) is mostly known as a proinflammatory cytokine. However, it also has regenerative and anti-inflammatory effects. It is supposed that this cytokine is likely to play a significant role in the process of co...

Laser plasmas as x-ray sources for lithographic imaging of submicron structures

International Nuclear Information System (INIS)

Bijkerk, F.; van Dorssen, G.E.; van der Wiel, M.J.

1988-01-01

Laser radiation can be used efficiently to generate x-rays for lithographic imaging of submicron patterns, e.g., for VLSI device fabrication. Due to their short wavelength and high average power, excimer lasers show much potential for this application. Results are presented of scaling studies for high repetition rate excimer laser application, using the frequency doubled output of a low repetition rate Nd:YAG/Glass laser. Spectral and spatial characteristics of x-ray emission of the laser plasma are shown. The power density in the laser focus was 3 x 10 12 W/cm 2 . With this source Si x-ray masks with submicron Au absorber profiles are imaged into high sensitivity x-ray photoresist. For the exposures 80 laser shots sufficed to yield high quality submicron structures. Extrapolation of the results to a high power excimer laser reduces the exposure time of the photoresists to several seconds, enabling a wafer throughput at an industrial level

Distinctive Spectral Features of Exciton and Excimer States in the Ultrafast Electronic Deactivation of the Adenine Dinucleotide

Science.gov (United States)

Stuhldreier, Mayra C.; Röttger, Katharina; Temps, Friedrich

We report the observation by transient absorption spectroscopy of distinctive spectro-temporal signatures of delocalized exciton versus relaxed, weakly bound excimer states in the ultrafast electronic deactivation after UV photoexcitation of the adenine dinucleotide.

Excimer laser crystallization of InGaZnO4 on SiO2 substrate

NARCIS (Netherlands)

Chen, T.; Wu, M.Y.; Ishihara, R.; Nomura, K.; Kamiya, T.; Hosono, H.; Beenakker, C.I.M.

2011-01-01

In this paper, we were able to crystallize InGaZnO4 (IGZO) by excimer laser on SiO2 substrate. It was observed that uniform [0001] textured polycrystalline IGZO film has been obtained without any grain boundaries and oxygen vacancies on SiO2 substrate. This process is very promising in fabricating

Endobronchial Forceps-Assisted and Excimer Laser-Assisted Inferior Vena Cava Filter Removal: The Data, Where We Are, and How It Is Done.

Science.gov (United States)

Chen, James X; Montgomery, Jennifer; McLennan, Gordon; Stavropoulos, S William

2018-06-01

The recognition of inferior vena cava filter related complications has motivated increased attentiveness in clinical follow-up of patients with inferior vena cava filters and has led to development of multiple approaches for retrieving filters that are challenging or impossible to remove using conventional techniques. Endobronchial forceps and excimer lasers are tools for designed to aid in complex inferior vena cava filter removals. This article discusses endobronchial forceps-assisted and excimer laser-assisted inferior vena cava filter retrievals. Copyright © 2018 Elsevier Inc. All rights reserved.

Comparison of KrF and ArF excimer laser treatment of biopolymer surface

Energy Technology Data Exchange (ETDEWEB)

Michaljaničová, I. [Department of Solid State Engineering, University of Chemistry and Technology, 166 28 Prague (Czech Republic); Slepička, P., E-mail: petr.slepicka@vscht.cz [Department of Solid State Engineering, University of Chemistry and Technology, 166 28 Prague (Czech Republic); Heitz, J.; Barb, R.A. [Institute of Applied Physics, Johannes Kepler University Linz, A-4040 Linz (Austria); Sajdl, P. [Department of Power Engineering, University of Chemistry and Technology, 166 28 Prague (Czech Republic); Švorčík, V. [Department of Solid State Engineering, University of Chemistry and Technology, 166 28 Prague (Czech Republic)

2015-06-01

Highlights: • The influence of ArF and KrF laser on biopolymer surface was determined. • ArF laser acts predominantly on biopolymer surface. • PHB roughness is increased similarly for both applied wavelengths. • Roughness of nanostructures can be precisely controlled. • ArF laser introduces nitrogen on PHB surface. - Abstract: The goal of this work was the investigation of the impact of two different excimer lasers on two biocompatible and biodegradable polymers (poly-L-lactide and poly hydroxybutyrate). Both polymers find usage in medical and pharmaceutical fields. The polymers were modified by KrF and ArF excimer lasers. Subsequently the impact on surface morphology, surface chemistry changes, and thermal properties was studied by means of confocal and AFM microscopy, FTIR and XPS spectroscopy and DSC calorimetry. Under the same conditions of laser treatment it was observed that ArF laser causes more significant changes on surface chemistry, surface morphology and pattern formation on the polymers under investigation. The data obtained in this work can be used for a wide range of possible applications, in tissue engineering or in combination with metallization in electronics, e.g. for biosensors.

High Efficiency Power Converter for Low Voltage High Power Applications

DEFF Research Database (Denmark)

Nymand, Morten

The topic of this thesis is the design of high efficiency power electronic dc-to-dc converters for high-power, low-input-voltage to high-output-voltage applications. These converters are increasingly required for emerging sustainable energy systems such as fuel cell, battery or photo voltaic based......, and remote power generation for light towers, camper vans, boats, beacons, and buoys etc. A review of current state-of-the-art is presented. The best performing converters achieve moderately high peak efficiencies at high input voltage and medium power level. However, system dimensioning and cost are often...

Effects of Intermolecular Coupling on Excimer Formation and Singlet Fission

Science.gov (United States)

Mauck, Catherine McKay

The development of organic photovoltaic devices benefits from understanding the fundamental processes underlying charge generation in thin films of organic semiconductors. This dissertation exploits model systems of pi-stacked chromophores such as perylene-3,4:9,10-bis(dicarboximide) (PDI) and 3,6-bis(aryl)diketopyrrolopyrrole (DPP) to study these processes using ultrafast electronic and vibrational spectroscopy. In particular, the characterization of covalent molecular dimers, thin films, and solution aggregates can reveal how supramolecular order affects photophysical properties. PDI and DPP are organic semiconductors that have been widely studied in organic photovoltaics, due to their strong visible absorption and excellent chemical stability. As solution-phase monomers, they are highly fluorescent, but in the thin film environment of photovoltaic devices these planar aromatic molecules couple to one another, stacking largely through pi-pi interactions. In self-assembled stacks of PDI, strong interchromophore coupling may disrupt charge separation through the formation of excimer states, preventing the generation of free carriers. By studying molecular dimers of PDI with different pi-stacked geometry, femtosecond visible pump mid-infrared probe spectroscopy allows direct observation of the structural dynamics associated with excimer state relaxation, showing that this low-energy state is primarily coupled to the core modes that shift as planarization and rotation lead to the most stable excimer geometry. PDI is also able to undergo singlet fission in thin films and aggregates. Singlet fission is the process in which a singlet excited state is downconverted into two triplet excitons, when the energy of its first singlet excited state is at least twice the energy of the lowest triplet state in an appropriately coupled molecular system. This spin-allowed, ultrafast process enables a theoretical yield of two charge carriers per incident photon, making it a

Green synthesis of selenium nanoparticles by excimer pulsed laser ablation in water

OpenAIRE

O. Van Overschelde; G. Guisbiers; R. Snyders

2013-01-01

Pure selenium nanoparticles were successfully synthesized by Liquid Phase - Pulsed Laser Ablation (LP-PLA) in de-ionized water. Excimer laser (248 nm) operating at low fluence (F ∼ 1 J/cm2) was used to generate colloidal solutions of selenium nanoparticles. The obtained selenium nanoparticles were characterized by UV-visible spectroscopy, Raman spectroscopy, Dynamic Light Scattering, and Transmission Electron Microscopy. We describe the multi-modal size distributions generated and use the cen...

Excimer Laser Surgery: Biometrical Iris Eye Recognition with Cyclorotational Control Eye Tracker System.

Science.gov (United States)

Pajic, Bojan; Cvejic, Zeljka; Mijatovic, Zoran; Indjin, Dragan; Mueller, Joerg

2017-05-25

A prospective comparative study assessing the importance of the intra-operative dynamic rotational tracking-especially in the treatment of astigmatisms in corneal refractive Excimer laser correction-concerning clinical outcomes is presented. The cyclotorsion from upright to supine position was measured using iris image comparison. The Group 1 of patients was additionally treated with cyclorotational control and Group 2 only with X-Y control. Significant differences were observed between the groups regarding the mean postoperative cylinder refraction ( p < 0.05). The mean cyclotorsion can be calculated to 3.75° with a standard deviation of 3.1°. The total range of torsion was from -14.9° to +12.6°. Re-treatment rate was 2.2% in Group 1 and 8.2% in Group 2, which is highly significant ( p < 0.01). The investigation confirms that the dynamic rotational tracking system used for LASIK results in highly predictable refraction quality with significantly less postoperative re-treatments.

Development in high speed and high quality laser cutting process in fiber reinforced plastics; FRP no laser ni yoru kosoku, kohinshitsu setsudan gijutsu no kaihatsu

Energy Technology Data Exchange (ETDEWEB)

Ishide, T.; Shirota, H.; Matsumoto, O. [Mitsubishi Heavy Industries, Ltd., Tokyo (Japan)

1996-06-01

Trimming was performed and studied by cutting KFRP, an epoxy matrix with Kevlar fiber woven thereinto, using various laser beams. The CO2 laser is capable of high-speed cutting but the product is low in quality. The surface of a cut by the YAG laser is not high in quality even with its peak output elevated. The thermally affected area is smaller under the excimer laser but it is low in cutting speed. The ablation properties of the excimer laser were investigated and the beam was shaped into a linear beam for another experiment, but it failed to attain the target speed of cutting. Next, a combination of excimer laser and CO2 laser was used for cutting. It was so designed that the preceding CO2 laser cuts the KFRP at a high speed to leave behind a carbonized layer, which is followed by a linear beam which vaporizes the carbonized layer for removal. An optical system is adopted for reshaping the excimer oscillated beam into a tube-like beam. Optical conditions were determined for a fluence value required for the removal of the carbonized layer. When the CO2 laser was set at 160W and the excimer laser at 20W, a 1mm-thick sheet was successfully cut at a speed of 16.7mm/sec. 3 refs., 7 figs.

Fabrication of SERS Active Surface on Polyimide Sample by Excimer Laser Irradiation

Directory of Open Access Journals (Sweden)

T. Csizmadia

2014-01-01

Full Text Available A possible application of excimer laser irradiation for the preparation of surface enhanced Raman spectroscopy (SERS substrate is demonstrated. A polyimide foil of 125 μm thickness was irradiated by 240 pulses of focused ArF excimer laser beam (λ = 193 nm, FWHM = 20 ns. The applied fluence was varied between 40 and 80 mJ/cm2. After laser processing, the sample was coated with 40 nm silver by PLD in order to create a conducting layer required for the SERS application. The SERS activity of the samples was tested by Raman microscopy. The Raman spectra of Rhodamine 6G aqueous solution (c=10−3 mol/dm3 were collected from the patterned and metalized areas. For areas prepared at 40–60 mJ/cm2 laser fluences, the measured Raman intensities have shown a linear dependence on the applied laser fluence, while above 60 mJ/cm2 saturation was observed. The morphology of the SERS active surface areas was investigated by scanning electron microscopy. Finite element modeling was performed in order to simulate the laser-absorption induced heating of the polyimide foil. The simulation resulted in the temporal and spatial distribution of the estimated temperature in the irradiated polyimide sample, which are important for understanding the structure formation process.

An experimental study on laser drilling and cutting of composite materials for the aerospace industry using excimer and CO2 sources

Science.gov (United States)

dell'Erba, M.; Galantucci, L. M.; Miglietta, S.

This paper reports on the results of research which investigated the potential for the application of an excimer laser in the field of composite material drilling and cutting, by comparing this technology with that using CO2 sources. In particular, the scope of the work was to check whether the interaction between excimer lasers and composite materials, whose characteristic feature is the absence of thermal transfer, could yield better results than those obtainable with CO2 sources once heat transfer-induced difficulties had been eliminated. The materials selected for the experiments were multilayer composites having an epoxy resin matrix (65 percent in volume), with aramid fiber (Kevlar), carbon fiber and glass fiber as reinforcing materials, all of considerable interest for the aerospace industry. Optimal operational parameters were identified in relation to each source with a view to obtaining undersize holes or through cuts exhibiting severed areas of good quality. A comparison between the two types of processing carried out show that rims processed by excimer lasers are of better quality - particularly so with Kevlar - whereas the ablation rate is undoubtedly rather low compared with the CO2 technology.

Update on excimer laser photorefractive keratectomy (PRK) at Cedars-Sinai Medical Center: two-year experience

Science.gov (United States)

Maguen, Ezra I.; Salz, James J.; Warren, Cathy; Papaioannou, Thanassis; Nesburn, Anthony B.; Macy, Jonathan I.; Hofbauer, John; Grundfest, Warren S.

1993-06-01

Our two year experience with excimer laser photorefractive keratectomy for the correction of myopia on 160 eyes of 128 patients is described. All eyes were treated with a VISX Twenty- Twenty excimer laser, with the following parameters: radiant exposure 160 mJ/cm2, frequency 5 Hz, ablation zone diameter 5.0 to 5.5 mm, and stromal ablation rate 0.18 to 0.33 (mu) /pulse. A suction fixation ring was used in all cases either with nitrogen flow (79 eyes) or without nitrogen flow (81 eyes) across the cornea. Follow-up ranged from one month (152 eyes) to 24 months (12 eyes). The results are stable between 3 and 24 months with less than 0.25 D change in the mean postoperative spherical equivalents. In eyes with a follow-up of 6 to 24 months, 77% to 100% were 20/40 or better uncorrected, and 84% to 92% were corrected to within +/- 1 D of emmetropia. Further follow-up is needed to assess the long term safety and efficacy of the procedure.

Evaluation and diffusion of excimer laser treatment of myopia in the United States and in the Netherlands

NARCIS (Netherlands)

Vondeling, H.; Rosendal, H.; Banta, D.

1995-01-01

Excimer laser photorefractive keratectomy (PRK) is an experimental treatment to correct myopia (short-sightedness) that is diffusing into use without convincing evidence of safety and efficacy. It has been claimed that PRK may render conventional methods of correcting myopia, such as wearing glasses

Exciplex and excimer molecular probes: detection of conformational flip in a myo-inositol chair.

Science.gov (United States)

Kadirvel, Manikandan; Arsic, Biljana; Freeman, Sally; Bichenkova, Elena V

2008-06-07

2-O-tert-Butyldimethylsilyl-4,6-bis-O-pyrenoyl-myo-inositol-1,3,5-orthoformate (6) and 2-O-tert-butyldimethylsilyl-4-O-[4-(dimethylamino)benzoyl]-6-O-pyrenoyl-myo-inositol-1,3,5-orthoacetate (10) adopt conformationally restricted unstable chairs with five axial substituents. In the symmetrical diester 6, the two pi-stacked pyrenoyl groups are electron acceptor-donor partners, giving a strong intramolecular excimer emission. In the mixed ester 10, the pyrenoyl group is the electron acceptor and the 4-(dimethylamino)benzoyl ester is the electron donor, giving a strong intramolecular exciplex emission. The conformation of the mixed ester 10 was assessed using 1H NMR spectroscopy (1H-NOESY) and computational studies. which showed the minimum inter-centroid distance between the two aromatic systems to be approximately 3.9 A. Upon addition of acid, the orthoformate/orthoacetate trigger in 6 and 10 was cleaved, which caused a switch of the conformation of the myo-inositol ring to the more stable penta-equatorial chair, leading to separation of the aromatic ester groups and loss of excimer and exciplex fluorescence, respectively. This study provides proof of principle for the development of novel fluorescent molecular probes.

Optical and electronic properties of HWCVD and PECVD silicon films irradiated using excimer and Nd:Yag lasers

International Nuclear Information System (INIS)

Shaikh, M.Z.; O'Neill, K.A.; Anthony, S.; Persheyev, S.K.; Rose, M.J.

2006-01-01

Thin silicon film samples were deposited using HWCVD and PECVD techniques to study the influence of laser annealing on their optical and electronic properties. Samples were annealed in air using a XeCl excimer and Nd:Yag lasers. Excimer laser annealing (ELA) at 50 to 222 mJ/cm 2 increased conductivity in PECVD films by 2 to 3 orders of magnitude and in HWCVD films by 1 to 2 orders of magnitude. ELA was also seen to decrease the optical gap in PECVD films by 0.5 eV and HWCVD films by 0.15 eV. Silicon-oxygen bond content was higher in as-deposited HWCVD films than PECVD films. Hydrogen content (at.%) in PECVD films was higher than HWCVD for higher H dilution ratios. A Nd:Yag laser 3-beam interference pattern was used to produce a periodic array of crystals in both PECVD and HWCVD films

Elimination of chlorohydrocarbons from water by vacuum UV and UV photolysis in excimer flow-through photoreactors

International Nuclear Information System (INIS)

Oppenlaender, T.; Baum, G.

1995-01-01

It is shown that chlorinated hydrocarbons can be eliminated efficiently from water in an excimer flow photoreactor by complete photomineralisation induced by VUV irradiation. The problem of stripping of chlorohydrocarbons can be avoided by carrying out irradiation in a sealed apparatus without external supply of air or ozone. (orig.) [de

Improvement of physical properties of IGZO thin films prepared by excimer laser annealing of sol–gel derived precursor films

International Nuclear Information System (INIS)

Tsay, Chien-Yie; Huang, Tzu-Teng

2013-01-01

Indium gallium zinc oxide (IGZO) transparent semiconductor thin films were prepared by KrF excimer laser annealing of sol–gel derived precursor films. Each as-coated film was dried at 150 °C in air and then annealed using excimer laser irradiation. The influence of laser irradiation energy density on surface conditions, optical transmittances, and electrical properties of laser annealed IGZO thin films were investigated, and the physical properties of the excimer laser annealed (ELA) and the thermally annealed (TA) thin films were compared. Experimental results showed that two kinds of surface morphology resulted from excimer laser annealing. Irradiation with a lower energy density (≤250 mJ cm −2 ) produced wavy and irregular surfaces, while irradiation with a higher energy density (≥350 mJ cm −2 ) produced flat and dense surfaces consisting of uniform nano-sized amorphous particles. The explanation for the differences in surface features and film quality is that using laser irradiation energy to form IGZO thin films improves the film density and removes organic constituents. The dried IGZO sol–gel films irradiated with a laser energy density of 350 mJ/cm 2 had the best physical properties of all the ELA IGZO thin films. The mean resistivity of the ELA 350 thin films (4.48 × 10 3 Ω cm) was lower than that of TA thin films (1.39 × 10 4 Ω cm), and the average optical transmittance in the visible range (90.2%) of the ELA 350 thin films was slightly higher than that of TA thin films (89.7%). - Highlights: • IGZO semiconductor films were prepared by laser annealing of sol–gel derived films. • Surface roughness and resistivity of ELA samples were affected by energy density. • The ELA 350 IGZO film exhibited the best properties among all of ELA IGZO films. • Transmittance and resistivity of ELA 350 films are greater than those of TA films

Improvement of physical properties of IGZO thin films prepared by excimer laser annealing of sol–gel derived precursor films

Energy Technology Data Exchange (ETDEWEB)

Tsay, Chien-Yie, E-mail: cytsay@fcu.edu.tw; Huang, Tzu-Teng

2013-06-15

Indium gallium zinc oxide (IGZO) transparent semiconductor thin films were prepared by KrF excimer laser annealing of sol–gel derived precursor films. Each as-coated film was dried at 150 °C in air and then annealed using excimer laser irradiation. The influence of laser irradiation energy density on surface conditions, optical transmittances, and electrical properties of laser annealed IGZO thin films were investigated, and the physical properties of the excimer laser annealed (ELA) and the thermally annealed (TA) thin films were compared. Experimental results showed that two kinds of surface morphology resulted from excimer laser annealing. Irradiation with a lower energy density (≤250 mJ cm{sup −2}) produced wavy and irregular surfaces, while irradiation with a higher energy density (≥350 mJ cm{sup −2}) produced flat and dense surfaces consisting of uniform nano-sized amorphous particles. The explanation for the differences in surface features and film quality is that using laser irradiation energy to form IGZO thin films improves the film density and removes organic constituents. The dried IGZO sol–gel films irradiated with a laser energy density of 350 mJ/cm{sup 2} had the best physical properties of all the ELA IGZO thin films. The mean resistivity of the ELA 350 thin films (4.48 × 10{sup 3} Ω cm) was lower than that of TA thin films (1.39 × 10{sup 4} Ω cm), and the average optical transmittance in the visible range (90.2%) of the ELA 350 thin films was slightly higher than that of TA thin films (89.7%). - Highlights: • IGZO semiconductor films were prepared by laser annealing of sol–gel derived films. • Surface roughness and resistivity of ELA samples were affected by energy density. • The ELA 350 IGZO film exhibited the best properties among all of ELA IGZO films. • Transmittance and resistivity of ELA 350 films are greater than those of TA films.

Intramolecular excimer formation of diastereoisomeric model compounds of polystyrene in fluid solution: their local molecular motion and photophysical properties

International Nuclear Information System (INIS)

Itagaki, Hideyuki; Horie, Kazuyuki; Mita, Itaru; Washio, Masakazu; Tagawa, Seiichi; Tabata, Yoneho

1989-01-01

The dynamic process of intramolecular excimer formation in diasteroisomeric oligomers model compounds of polystyrene, was investigated by using a picosecond pulse radiolysis technique. Monomer fluorescence of all-racemic isomers decays single-exponentially, while that of other isomers decays dual-exponentially. Multicomponent fluorescence decay curves are supposed to be mainly induced by conformational changes. The results suggest that the excimer in oligostyrenes (or polystyrene) is formed mainly in meso diad. It is definitely proved that there exists singlet energy migration in styrene trimer and tetramer systems. The conformational change in PS3 and PS4 is concluded to occur by way of cooperative motions in backbone chains bond such as a crankshaft transition, not by way of independent rotation around each carbon-carbon bond of the backbone chain. (author)

Green synthesis of selenium nanoparticles by excimer pulsed laser ablation in water

Directory of Open Access Journals (Sweden)

O. Van Overschelde

2013-10-01

Full Text Available Pure selenium nanoparticles were successfully synthesized by Liquid Phase - Pulsed Laser Ablation (LP-PLA in de-ionized water. Excimer laser (248 nm operating at low fluence (F ∼ 1 J/cm2 was used to generate colloidal solutions of selenium nanoparticles. The obtained selenium nanoparticles were characterized by UV-visible spectroscopy, Raman spectroscopy, Dynamic Light Scattering, and Transmission Electron Microscopy. We describe the multi-modal size distributions generated and use the centrifugation method to isolate the smallest nanoparticles (∼60 nm in diameter.

Topography-guided treatment of irregular astigmatism with the wavelight excimer laser.

Science.gov (United States)

Jankov, Mirko R; Panagopoulou, Sophia I; Tsiklis, Nikolaos S; Hajitanasis, Georgos C; Aslanides, loannis M; Pallikaris, loannis G

2006-04-01

To evaluate the feasibility, safety, and predictability of correcting high irregular astigmatism in symptomatic eyes with the use of topography-guided photoablation. In a prospective, non-comparative case series, 16 consecutive symptomatic eyes of 11 patients with small hyperopic and myopic excimer laser optical zones, decentered and irregular ablation after corneal graft, and corneal scars were operated. Uncorrected visual acuity (UCVA), best spectacle-corrected visual acuity (BSCVA), manifest and cycloplegic refraction, and corneal topography, with asphericity and regularity, were analyzed. LASIK (n = 10) and photorefractive keratectomy (n = 6) were performed using the ALLEGRETTO WAVE excimer laser and T-CAT software (Topography-guided Customized Ablation Treatment; WaveLight Laser Technologie AG, Erlangen, Germany). In the LASIK group, UCVA improved from 0.81 +/- 0.68 IogMAR (20/130) (range: 0.2 to 2.0) to 0.29 +/- 0.21 logMAR (20/39) (range: 0.1 to 0.7) at 6 months. In the PRK group, mean UCVA improved from 0.89 +/- 0.87 IogMAR (20/157) (range: 0.1 to 2.0) to 0.42 +/- 0.35 logMAR (20/53) (range: 0.1 to 1.0) at 6 months. Best spectacle-corrected visual acuity did not change significantly in either group. One PRK patient lost one line of BSCVA. Refractive cylinder for the LASIK group improved from -2.53 +/- 1.71 diopters (D) (range: -0.75 to -5.75 D) to -1.28 +/- 0.99 D (range: 0 to -2.50 D) at 6 months. Refractive cylinder in the PRK group improved from -2.21 +/- 2.11 D (range: -0.25 to -5.50 D) to -1.10 +/- 0.42 D (range: -0.50 to -1.50 D). Index of surface irregularity showed a decrease from 60 +/- 12 (range: 46 to 89) to 50 +/- 9 (range: 32 to 63) at 6 months in the LASIK group whereas no significant change was noted in the PRK group. Subjective symptoms, such as glare, halos, ghost images, starbursts, and monocular diplopia, were not present postoperatively. Topography-guided LASIK and PRK resulted in a significant reduction of refractive cylinder and

High Efficiency Power Converter for Low Voltage High Power Applications

DEFF Research Database (Denmark)

Nymand, Morten

The topic of this thesis is the design of high efficiency power electronic dc-to-dc converters for high-power, low-input-voltage to high-output-voltage applications. These converters are increasingly required for emerging sustainable energy systems such as fuel cell, battery or photo voltaic based...

Gasochromic performance of WO3-nanorod thin films fabricated with an ArF excimer laser

International Nuclear Information System (INIS)

Yaacob, M. H.; Ou, J. Z.; Wlodarski, W.; Kim, C. S.; Lee, J. Y.; Kim, Y. H.; Oh, C. M.; Dhakal, K. P.; Kim, J. Y.; Kang, J. H.

2012-01-01

Thin films with tungsten trioxide (WO 3 ) nanorods were fabricated by using an ArF pulsed laser deposition system. Because the ArF excimer laser operates at a very short wavelength of 193 nm, short enough to expect strong absorption of the photons in the semiconductor oxide targets, and because the clusters incoming to the substrates have high momentum, we could build thin films with good surface morphology. Highly homogeneous arrays of nanorods with sizes mostly in the range of 30 - 40 nm were observed. The absorbance response towards hydrogen (H 2 ) gas was investigated for a WO 3 film coated with 25-A-thick palladium (Pd). The Pd/WO 3 -nanorod thin films exhibited excellent gasochromic response when measured in the visible-NIR range (400 - 1000 nm). As low as 0.06% H 2 concentration was clearly sensed. A significant reversible absorbance change and fast recovery ( 2 at different concentrations.

Time-resolved spectroscopy and fluorescence resonance energy transfer in the study of excimer laser damage of chromatin

Energy Technology Data Exchange (ETDEWEB)

Radu, L. [Department of Molecular Genetics and Radiobiology, Babes National Institute, Bucharest (Romania)], E-mail: lilianajradu@yahoo.fr; Mihailescu, I. [Department of Lasers, Laser, Plasma and Radiation Physics Institute, Bucharest (Romania); Radu, S. [Department of Computer Science, Polytechnics University, Bucharest (Romania); Gazdaru, D. [Department of Biophysics, Bucharest University (Romania)

2007-09-21

The analysis of chromatin damage produced by a 248 nm excimer laser radiation, for doses of 0.3-3 MJ/m{sup 2} was carried out by time-resolved spectroscopy and fluorescence resonance energy transfer (FRET). The chromatin was extracted from a normal and a tumoral tissue of Wistar rats. The decrease with laser dose of the relative contribution of the excited state lifetimes of ethidium bromide (EtBr) bounded to chromatin constitutes an evidence of the reduction of chromatin deoxyribonucleic acid (DNA) double-strand structure. FRET was performed from dansyl chloride to acridine orange, both coupled to chromatin. The increase of the average distance between these ligands, under the action of laser radiation, reflects a loosening of the chromatin structure. The radiosensitivity of tumor tissue chromatin is higher than that of a normal tissue. The determination of the chromatin structure modification in an excimer laser field can be of interest in laser therapy.

Time-resolved spectroscopy and fluorescence resonance energy transfer in the study of excimer laser damage of chromatin

International Nuclear Information System (INIS)

Radu, L.; Mihailescu, I.; Radu, S.; Gazdaru, D.

2007-01-01

The analysis of chromatin damage produced by a 248 nm excimer laser radiation, for doses of 0.3-3 MJ/m 2 was carried out by time-resolved spectroscopy and fluorescence resonance energy transfer (FRET). The chromatin was extracted from a normal and a tumoral tissue of Wistar rats. The decrease with laser dose of the relative contribution of the excited state lifetimes of ethidium bromide (EtBr) bounded to chromatin constitutes an evidence of the reduction of chromatin deoxyribonucleic acid (DNA) double-strand structure. FRET was performed from dansyl chloride to acridine orange, both coupled to chromatin. The increase of the average distance between these ligands, under the action of laser radiation, reflects a loosening of the chromatin structure. The radiosensitivity of tumor tissue chromatin is higher than that of a normal tissue. The determination of the chromatin structure modification in an excimer laser field can be of interest in laser therapy

SF{sub 6} decomposition and layer formation due to excimer laser photoablation of SiO{sub 2} surface at gas-solid system

Energy Technology Data Exchange (ETDEWEB)

Sajad, Batool [Physics Department, Amirkabir University, PO Box 15875-4413, Tehran (Iran, Islamic Republic of); Parvin, Parviz [Physics Department, Amirkabir University, PO Box 15875-4413, Tehran (Iran, Islamic Republic of); Bassam, Mohamad Amin [Excimer Laser Lab, Emam Hussain University, PO Box 16575-4347, Tehrann (Iran, Islamic Republic of)

2004-12-21

In this work, the effect of an excimer laser has been studied for presenting a method for SF{sub 6} decomposition and simultaneous formation of a SiF{sub 2} layer on amorphous SiO{sub 2}. Though the excimer laser did not establish a gas phase photodissociation, we have shown that UV photoablation leads strongly to molecular decomposition in the SF{sub 6}-SiO{sub 2} system. Moreover, the dependence of the decomposition process on the exposure parameters such as the wavelength and intensity as well as the gas pressure and the focal point distance from the gas-solid interface has been investigated.

Improved model for the angular dependence of excimer laser ablation rates in polymer materials

Science.gov (United States)

Pedder, J. E. A.; Holmes, A. S.; Dyer, P. E.

2009-10-01

Measurements of the angle-dependent ablation rates of polymers that have applications in microdevice fabrication are reported. A simple model based on Beer's law, including plume absorption, is shown to give good agreement with the experimental findings for polycarbonate and SU8, ablated using the 193 and 248 nm excimer lasers, respectively. The modeling forms a useful tool for designing masks needed to fabricate complex surface relief by ablation.

Physical and optical limitations using ArF-excimer and Er:YAG lasers for PRK

Science.gov (United States)

Semchishen, Vladimir A.; Mrochen, Michael; Seiler, Theo

1998-06-01

The Erbium:YAG laser emitting at a wavelength of 2,94 micrometer have been promised as an alternative laser for the ArF-excimer laser (193 nm) in photorefractive keratectomy (PRK). This report discusses the limitations of laser parameters such as wavelength, energy density and pulse duration for the ablation of the cornea. In addition, the melting process during ablation on the corneal surface roughness may play a role.

Visual and refractive outcomes following myopic laser-assisted subepithelial keratectomy with a flying-spot excimer laser.

Science.gov (United States)

McAlinden, Colm; Skiadaresi, Eirini; Moore, Jonathan E

2011-05-01

To investigate the visual and refractive outcomes following laser-assisted subepithelial keratectomy (LASEK) surgery with a flying-spot excimer laser. Private practice, Ireland. Case series. In this prospective study, the mean manifest spherical equivalent (SE), sphere, and cylinder were measured preoperatively. All eyes had LASEK surgery with an aberration-free algorithm with the Schwind Amaris excimer laser. Outcomes measured at 1 month, 6 months, and 1 year were uncorrected distance visual acuity (UDVA), manifest refraction, corrected distance visual acuity, contrast sensitivity, aberrometry, and complications. Accuracy, efficacy, and safety were evaluated at 1 year. Preoperatively, the mean SE, sphere, and cylinder in the 80 eyes (48 patients) were -3.58 diopters (D) ± 2.00 (SD), -3.23 ± 1.93 D, and -0.85 ± 0.65 D, respectively. One year postoperatively, the mean SE was -0.00 ± 0.22 D; 57 eyes (71%) were within -0.13 to +0.13 D of the SE, and 71 eyes (98%) were within ±0.50 D. The mean UDVA was -0.06 ± 0.07 logMAR, with an efficacy index of 1.04. The postoperative SE was stable between 1 month, 3 months, and 1 year. One eye (1%) had a change in SE by more than 0.50 D at 6 months and 1 year. There were no statistically significant differences in any aberrations at 1 year. The contrast sensitivity improved from 1.66 ± 0.17 log units preoperatively to 1.72 ± 0.15 log units at 1 month postoperatively (P=.0003), which was unchanged at 6 months and 1 year. This study demonstrated the effectiveness of LASEK for the treatment of myopia with this flying-spot excimer laser. Copyright © 2011 ASCRS and ESCRS. Published by Elsevier Inc. All rights reserved.

Structural and morphological transformations of TiO2 nanotube arrays induced by excimer laser treatment

International Nuclear Information System (INIS)

Hsu, Ming-Yi; Thang, Nguyen Van; Wang Chih; Leu Jihperng

2012-01-01

The structural and morphological transformations of TiO 2 nanotube arrays (TNAs) treated by excimer laser annealing (ELA) were investigated as a function of the laser fluence using parallel and tilted modes. Results showed that the crystallinity of the ELA-treated TNAs reached only about 50% relative to that of TNAs treated by furnace anneal at 400 °C for 1 h. The phase transformation starts from the top surface of the TNAs with surface damage resulting from short penetration depth and limited one-dimensional heat transport from the surface to the bottom under extremely short pulse duration (25 ns) of the excimer laser. When a tilted mode was used, the crystallinity of TNAs treated by ELA at 85° was increased to 90% relative to that by the furnace anneal. This can be attributed to the increased area of the laser energy interaction zone and better heat conduction to both ends of the TNAs. - Highlights: ► We examined the morphology and microstructure of TNAs treated by ELA. ► Crystallinity of parallel ELA-treated TNAs reached ∼50% of furnace anneal. ► Tilted ELA at 85o enhanced the degree of crystallization in TNAs to 90%.

Levels of interleukin-6 in tears before and after excimer laser treatment

Directory of Open Access Journals (Sweden)

Resan Mirko

2015-01-01

Full Text Available Background/Aim. Immune response and consequent inflammatory process which originate on ocular surface after a trauma are mediated by cytokines. Photoablation of corneal stroma performed by excimer laser causes surgically induced trauma. Interleukin-6 (IL-6 is mostly known as a proinflammatory cytokine. However, it also has regenerative and anti-inflammatory effects. It is supposed that this cytokine is likely to play a significant role in the process of corneal wound healing response after photoablation of stroma carried out by laser in situ keratomileusis (LASIK or photorefractive keratectomy (PRK methods. The aim of this study was to determine and compare the levels of IL-6 in tears before and after treatment with LASIK and PRK methods. Methods. The study included 68 shortsighted eyes up to -3.0 diopter sphere, i.e. 198 samples of tears (per three samples taken from each of the eyes, divided into two groups according to the kind of excimer laser intervention performed: the group 1 - eyes treated by LASIK method (n = 31, and the group 2 - eyes treated by the PRK method (n = 37. The samples of tears were taken from each eye at the following time points: before excimer laser treatment (0 h, the control group, 1 h after the treatment (1 h and 24 h after the treatment (24 h. The patients did not use anti-inflammatory therapy 24 h after the intervention. Tear samples were collected using microsurgical sponge. Level of IL-6 in tear fluid was determined by the flow cytometry method, applying a commercial test kit which allowed cytokine detection from a small sample volume. Results. The values of IL-6 were detectable in 16% of samples before LASIK treatment and in 30% of samples before PRK treatment. One h after the treatment IL-6 was detectable in 29% of samples for the LASIK group and 43% of samples for the PRK group, and 24 h after the treatment it was detectable in 19% of samples for the LASIK group and in 57% of samples for the PRK group. When we

Levels of interleukin-6 in tears before and after excimer laser treatment.

Science.gov (United States)

Resan, Mirko; Stanojević, Ivan; Petković, Aleksandra; Pajić, Bojan; Vojvodić, Danilo

2015-04-01

Immune response and consequent inflammatory process which originate on ocular surface after a trauma are mediated by cytokines. Photoablation of corneal stroma performed by excimer laser causes surgically induced trauma. Interleukin-6 (IL-6) is mostly known as a proinflammatory cytokine. However, it also has regenerative and anti-inflammatory effects. It is supposed that this cytokine is likely to play a significant role in the process of corneal wound healing response after photoablation of stroma carried out by laser in situ keratomileusis (LASIK) or photorefractive keratectomy (PRK) methods. The aim of this study was to determine and compare the levels of IL-6 in tears before and after treatment with LASIK and PRK methods. The study included 68 shortsighted eyes up to -3.0 diopter sphere, i.e. 198 samples of tears (per three samples taken from each of the eyes), divided into two groups according to the kind of excimer laser intervention performed: the group 1--eyes treated by LASIK method (n=31), and the group 2--eyes treated by the PRK method (n=37). The samples of tears were taken from each eye at the following time points: before excimer laser treatment (0 h, the control group), 1 h after the treatment (1 h) and 24 h after the treatment (24 h). The patients did not use anti-inflammatory therapy 24 h after the intervention. Tear samples were collected using microsurgical sponge. Level of IL-6 in tear fluid was determined by the flow cytometry method, applying a commercial test kit which allowed cytokine detection from a small sample volume. Results. The values of IL-6 were detectable in 16% of samples before LASIK treatment and in 30% of samples before PRK treatment. One h after the treatment IL-6 was detectable in 29% of samples for the LASIK group and 43% of samples for the PRK group, and 24 h after the treatment it was detectable in 19% of samples for the LASIK group and in 57% of samples for the PRK group. When we analyzed the dynamics of IL76 production

Research and development project in fiscal 1990 for large industrial technologies. Achievement report on research and development of ultra-advanced processing systems (Development of high-level processing devices for electric power generation facility members); 1990 nendo chosentan kako system no kenkyu kaihatsu seika hokokusho. Hatsuden shisetsuyo buzai kodo kako sochi kaihatsu

Energy Technology Data Exchange (ETDEWEB)

NONE

1991-03-01

Research and development has been performed with an objective to establish the processing technology using excitation beam required for the advanced technology industries, and the ultra-precision machining technology to realize the nano-technology. This paper summarizes the achievements in fiscal 1990. In the research on the large output and long life technology for excimer laser, an average output of 500 W or more was demonstrated achieving the intermediate target by developing and improving the technologies for low electric power gas circulation, high efficiency discharge and excitation, and large output oscillation control. In the research on intensity resistant optical element technology, a prototype device was fabricated to create and process axially symmetrical aspherical shapes, whereas SiC aspherical shape creation and processing were demonstrated at the shape accuracy of three microns or better, and surface roughness of 20 nanometers or less, having achieved the intermediate target. Regarding the large current ion beam, a demonstration device was completed based on improvements and test results on the sheet plasma generator. In the research and development of the high-level processing technology, low-temperature forming technology was developed for oxide ceramic thin films by using the excimer laser abrasion method. (NEDO)

150 keV intense electron beam accelerator system with high repeated pulse

International Nuclear Information System (INIS)

Qi, Zhang; Tixing, Li; Hongfang, Tang; Nenggiao, Xia; Zhigin, Wang; Baohong, Zheng

1993-01-01

A 150 keV electron beam accelerator system has been developed for wide application of high power particle beams. The new wire-ion-plasma electron gun has been adopted. The parameters are as follows: Output energy - 130-150 keV; Electron beam density - 250 mA/cm 2 ; Pulse duration - 1 μs; Pulse rate 100 pps; Section of electron beam - 5 x 50 cm 2 . This equipment can be used to study repeated pulse CO 2 laser, to be a preionizer of high power discharge excimer laser and to perform radiation curing process, and so on. The first part contains principle and design consideration. Next is a description of experimental arrangement. The remainder is devoted to describing experimental results and its application

High power klystrons for efficient reliable high power amplifiers

Science.gov (United States)

Levin, M.

1980-11-01

This report covers the design of reliable high efficiency, high power klystrons which may be used in both existing and proposed troposcatter radio systems. High Power (10 kW) klystron designs were generated in C-band (4.4 GHz to 5.0 GHz), S-band (2.5 GHz to 2.7 GHz), and L-band or UHF frequencies (755 MHz to 985 MHz). The tubes were designed for power supply compatibility and use with a vapor/liquid phase heat exchanger. Four (4) S-band tubes were developed in the course of this program along with two (2) matching focusing solenoids and two (2) heat exchangers. These tubes use five (5) tuners with counters which are attached to the focusing solenoids. A reliability mathematical model of the tube and heat exchanger system was also generated.

Development of a Silicon Based Electron Beam Transmission Window for Use in a KrF Excimer Laser System

CERN Document Server

Gentile, C A; Hartfield, J W; Hawryluk, R J; Hegeler, F; Heitzenroeder, P J; Jun, C H; Ku, L P; Lamarche, P H; Myers, M C; Parker, J J; Parsells, R F; Payen, M; Raftopoulos, S; Sethian, J D

2002-01-01

The Princeton Plasma Physics Laboratory (PPPL), in collaboration with the Naval Research Laboratory (NRL), is currently investigating various novel materials (single crystal silicon, , and ) for use as electron-beam transmission windows in a KrF excimer laser system. The primary function of the window is to isolate the active medium (excimer gas) from the excitation mechanism (field-emission diodes). Chosen window geometry must accommodate electron energy transfer greater than 80% (750 keV), while maintaining structural integrity during mechanical load (1.3 to 2.0 atm base pressure differential, approximate 0.5 atm cyclic pressure amplitude, 5 Hz repetition rate) and thermal load across the entire hibachi area (approximate 0.9 W centre dot cm superscript ''-2''). In addition, the window must be chemically resistant to attack by fluorine free-radicals (hydrofluoric acid, secondary). In accordance with these structural, functional, and operational parameters, a 22.4 mm square silicon prototype window, coated w...

Excimer laser correction of hyperopia, hyperopic and mixed astigmatism: past, present, and future.

Science.gov (United States)

Lukenda, Adrian; Martinović, Zeljka Karaman; Kalauz, Miro

2012-06-01

The broad acceptance of "spot scanning" or "flying spot" excimer lasers in the last decade has enabled the domination of corneal ablative laser surgery over other refractive surgical procedures for the correction of hyperopia, hyperopic and mixed astigmatism. This review outlines the most important reasons why the ablative laser correction of hyperopia, hyperopic and mixed astigmatism for many years lagged behind that of myopia. Most of today's scanning laser systems, used in the LASIK and PRK procedures, can safely and effectively perform low, moderate and high hyperopic and hyperopic astigmatic corrections. The introduction of these laser platforms has also significantly improved the long term refractive stability of hyperopic treatments. In the future, further improvements in femtosecond and nanosecond technology, eye-tracker systems, and the development of new customized algorithms, such as the ray-tracing method, could additionally increase the upper limit for the safe and predictable corneal ablative laser correction ofhyperopia, hyperopic and mixed astigmatism.

Periodic morphological modification developed on the surface of polyethersulfone by XeCl excimer laser photoablation

International Nuclear Information System (INIS)

Niino, H.; Nakano, M.; Nagano, S.; Yabe, A.; Miki, T.; Center for Structure Analyses, Teijin Limited, Asahigaoka, Hino, Tokyo, 191 Japan)

1989-01-01

Periodic and stable micropatterns appeared on the surface of amorphous polyethersulfone etched with an excimer laser at 308 nm in ambient air and a vacuum. The control of such radiative conditions as fluence and incident angle enables us to modify the spacing and pattern of the microstructures. A topographical investigation with scanning electron microscopy and an experiment with x-ray photoelectron spectroscopy to determine its composition is reported

The European answer to the integration issues of excimer laser annealing in MOS technology

International Nuclear Information System (INIS)

Privitera, V.; La Magna, A.; Fortunato, G.; Camalleri, M.; Magri, A.; Simon, F.; Svensson, B.G.

2004-01-01

Excimer laser annealing (ELA) of MOSFET devices is currently studied and evaluated within the frame of the IST project 'Fundamentals and applications of laser processing for highly innovative MOS technology' (FLASH), funded by the European Commission. This European consortium aim to demonstrate that ELA can be industrialized in the context of semiconductor device fabrication. The technical achievement of homogeneous irradiation of entire wafers by industrial line beam system set up has been combined with device design solutions, in order to avoid the detrimental effects of the laser beam on device structures and tackle the integration issues, main obstacles for the use of ELA in the semiconductor industry. The launch of ELA, to open a new market segment in the semiconductor industry, implies also the availability of reliable process simulation tools. Therefore, a simulation program based on the phase-field method was produced, fully working and available

Laser-induced breakdown spectra of Zn2 molecule in the violet region

Indian Academy of Sciences (India)

The study of excimer and van der Waals molecules such as Hg2, Cd2 and Zn2 are of current interest as they are potential candidates for the possible development of new high power excimer lasers. Group IIB metal dimers (Hg2, Cd2 and Zn2) have essentially repulsive ground states with very shallow van der Walls minima.

High-power klystrons

Science.gov (United States)

Siambis, John G.; True, Richard B.; Symons, R. S.

1994-05-01

Novel emerging applications in advanced linear collider accelerators, ionospheric and atmospheric sensing and modification and a wide spectrum of industrial processing applications, have resulted in microwave tube requirements that call for further development of high power klystrons in the range from S-band to X-band. In the present paper we review recent progress in high power klystron development and discuss some of the issues and scaling laws for successful design. We also discuss recent progress in electron guns with potential grading electrodes for high voltage with short and long pulse operation via computer simulations obtained from the code DEMEOS, as well as preliminary experimental results. We present designs for high power beam collectors.

ArF Excimer Laser-induced Deposition of Ag/C Nanocomposite Thin Films in the Presence of n-Hexane

Czech Academy of Sciences Publication Activity Database

Gondal, M.A.; Fajgar, Radek; Chang, X.; Shen, K.; Xu, Q.

2014-01-01

Roč. 311, AUG 30 (2014), s. 95-100 ISSN 0169-4332 Grant - others:NNSFCH(CN) 51172044; NSFJP(CN) BK2011617; KFUPM(CN) RG 1311-1 Institutional support: RVO:67985858 Keywords : ArF excimer laser * nanocomposite * laser deposition Subject RIV: CH - Nuclear ; Quantum Chemistry Impact factor: 2.711, year: 2014

Photo-triggering and secondary electron produced ionization in electric discharge ArF* excimer lasers

Science.gov (United States)

Xiong, Zhongmin; Kushner, Mark J.

2011-10-01

Electric discharge excimer lasers are sustained in multi-atmosphere attaching gas mixtures that are typically preionized to enable a reproducible, uniform glow, which maximizes optical quality and gain. This preionization is often accomplished using UV light produced by a corona discharge within the plasma cavity. To quantify the relationship between corona discharge properties and those of the laser discharge, the triggering of electron avalanche by preionizing UV light in an electric discharge-pumped ArF* excimer laser was numerically investigated using a two-dimensional model. The preionizing UV fluxes were generated by a corona-bar discharge driven by the same voltage pulse as the main discharge sustained in a multi-atmospheric Ne/Ar/Xe/F2 gas mixture. The resulting peak photo-electron density in the inter-electrode spacing is around 108 cm-3, and its distribution is biased toward the UV source. The preionization density increases with increasing dielectric constant and capacitance of the corona bar. The symmetry and uniformity of the discharge are, however, improved significantly once the main avalanche develops. In addition to bulk electron impact ionization, the ionization generated by sheath accelerated secondary electrons was found to be important in sustaining the discharge current at experimentally observed values. At peak current, the magnitude of the ionization by sheath accelerated electrons is comparable to that from bulk electron impact in the vicinity of the cathode.

UV excimer laser and low temperature plasma treatments of polyamide materials

Science.gov (United States)

Yip, Yiu Wan Joanne

Polyamides have found widespread application in various industrial sectors, for example, they are used in apparel, home furnishings and similar uses. However, the requirements for high quality performance products are continually increasing and these promote a variety of surface treatments for polymer modification. UV excimer laser and low temperature plasma treatments are ideally suited for polyamide modification because they can change the physical and chemical properties of the material without affecting its bulk features. This project aimed to study the modification of polyamides by UV excimer laser irradiation and low temperature plasma treatment. The morphological changes in the resulting samples were analysed by scanning electron microscopy (SEM) and tapping mode atomic force microscopy (TM-AFM). The chemical modifications were studied by x-ray photoelectron spectroscopy (XPS), time-of-flight secondary ion mass spectrometry (ToF-SIMS) and chemical force microscopy (CFM). Change in degree of crystallinity was examined by differential scanning calorimetry (DSC). After high-fluence laser irradiation, topographical results showed that ripples of micrometer size form on the fibre surface. By contrast, sub-micrometer size structures form on the polyamide surface when the applied laser energy is well below its ablation threshold. After high-fluence laser irradiation, chemical studies showed that the surface oxygen content of polyamide is reduced. A reverse result is obtained with low-fluence treatment. The DSC result showed no significant change in degree of crystallinity in either high-fluence or low-fluence treated samples. The same modifications in polyamide surfaces were studied after low temperature plasma treatment with oxygen, argon or tetrafluoromethane gas. The most significant result was that the surface oxygen content of polyamide increased after oxygen and argon plasma treatments. Both treatments induced many hydroxyl (-OH) and carboxylic acid (-COOH

Switching power converters medium and high power

CERN Document Server

Neacsu, Dorin O

2013-01-01

An examination of all of the multidisciplinary aspects of medium- and high-power converter systems, including basic power electronics, digital control and hardware, sensors, analog preprocessing of signals, protection devices and fault management, and pulse-width-modulation (PWM) algorithms, Switching Power Converters: Medium and High Power, Second Edition discusses the actual use of industrial technology and its related subassemblies and components, covering facets of implementation otherwise overlooked by theoretical textbooks. The updated Second Edition contains many new figures, as well as

Excimer laser annealing of shallow As and B doped layers

International Nuclear Information System (INIS)

Monakhov, E.V.; Svensson, B.G.; Linnarsson, M.K.; Magna, A. La; Privitera, V.; Camalleri, M.; Fortunato, G.; Mariucci, L.

2004-01-01

Excimer laser annealing (ELA) of As-, B- and BF 2 -implanted Si has been studied by secondary ion mass spectrometry (SIMS), spreading resistance probe (SRP) and transmission electron microscopy (TEM). The implantations have been performed in the energy range from 1 to 30 keV with doses of 10 15 -10 16 cm -2 . ELA has been carried out with the energy densities in the range of 600-1200 mJ/cm 2 and the number of laser pulses from 1 to 10. It is shown that ELA results in a more uniform dopant distribution over the doped region with a more abrupt profile edge as compared to those after rapid thermal annealing (RTA). Besides, in contrast to RTA, ELA demonstrates a highly confined annealing effect, where the distribution of dopants below the melting region is not affected. SRP measurements demonstrate almost complete activation of the implanted dopants after ELA, and TEM does not reveal extended defects in the ELA-treated samples. The depth of the doped layers, abruptness of the profiles and the total doping dose as a function of ELA energy density and number of laser pulses are investigated. Computer simulations of ELA show a good agreement with the experimental data

Screening for psychiatric distress and low self-esteem in patients presenting for excimer laser surgery for myopia.

Science.gov (United States)

Kidd, B; Stark, C; McGhee, C N

1997-01-01

Patients presenting for photorefractive keratectomy (PRK) may have unusual psychological profiles. Certain psychological variables may impact treatment outcome, making early identification crucial. We report a controlled questionnaire study of psychiatric "anxiety/distress" and self-esteem in myopic patients who presented for excimer laser treatment. Ninety consecutive myopic individuals (patients) who presented for excimer laser PRK and 50 consecutive myopic individuals who presented to an optometrist for contact lens fitting (controls) were assessed using two self-completion questionnaires-the GHQ30 and Hudson Index of Self-Esteem ISE. The questionnaires were distributed during assessment for treatment. PRK patients had a 90% response rate for both questionnaires and control patients, 98% for GHQ30 and 100% for Hudson ISE. PRK patients were significantly older (p = 0.000003), had a greater myopic spherical equivalent refraction (p = 0.012) and had better spectacle-corrected visual acuity (p = 0.0096). No significant differences were demonstrated with regard to anxiety/distress in terms of absolute scores (p = 0.07), or the proportion of patients being positive or negative (p = 0.10). Similarly, self-esteem was not significantly different between the two groups (absolute scores p = 0.69; positive/negative p = 0.29). The high response rate shows that the GHQ30 and Hudson ISE are easy to use and well tolerated by myopes in a busy clinic setting. The fact that the patients were older, with a greater refractive error, may partly reflect the onset of contact lens intolerance. The psychological findings suggest that PRK patients cannot be considered more distressed or anxious than other myopic individuals. There is no evidence that their decision to undergo surgery is driven by abnormally low self-esteem.

In-vitro ablation of fibrocartilage by XeCl excimer laser

Science.gov (United States)

Buchelt, Martin; Papaioannou, Thanassis; Fishbein, Michael C.; Peters, Werner; Beeder, Clain; Grundfest, Warren S.

1991-07-01

A 308 nm excimer laser was employed for ablation of human fibrocartilage. Experiments were conducted in vitro. The tissue response was investigated with respect to dosimetry (ablation rate versus radiant exposure) and thermal effect (thermographic analysis). Irradiation was performed via a 600 um fiber, with radiant exposures ranging between 20mj/mm2 and 80mj/mm2, at 20Hz. The ablation rates were found to range from 3um/pulse to 80um/pulse depending on the radiant exposure and/or the applied pressure on the delivery system. Thermographic analysis, during ablation, revealed maximum average temperatures of about 65 degree(s)C. Similar measurements performed, for the purpose of comparison, with a CW Nd:YAG and a CW CO2 laser showed higher values, of the order of 200 degree(s)C.

Electric field dependence of the total excimer luminescence of xenon excited below the atomic ionization limit

International Nuclear Information System (INIS)

Anon.

1987-01-01

In the spectral region of interest (i.e., 11.1 eV ≤ h nu ≤ 11.9 eV), the photoionization yield of electrons from excited-state dimers of xenon, increases monotonically to relatively high values (e.g., Y(11.7 eV) = 0.43 electrons/absorbed photon). It is also known however, that the luminescence intensity excited by photons in this region is quite high, even at low pressures. These two observations can be reconciled only by assuming that one of the processes leading to excimer luminescence involves dimer-ion + electron recombination. If this assumption is correct, application of an electric field, with concomitant collection of the free charges generated by the incident photons, should lead to a decrease in luminescence intensity; moreover, this decrease should follow the energy dependence of the photoionization yield function. The present report demonstrates experimentally that this is indeed the case. Such experiments combining luminescence and electric fields were made, until now, only by high-energy excitation. In this case the deconvolution of the various decay channels is hardly possible

Low Power Design with High-Level Power Estimation and Power-Aware Synthesis

CERN Document Server

Ahuja, Sumit; Shukla, Sandeep Kumar

2012-01-01

Low-power ASIC/FPGA based designs are important due to the need for extended battery life, reduced form factor, and lower packaging and cooling costs for electronic devices. These products require fast turnaround time because of the increasing demand for handheld electronic devices such as cell-phones, PDAs and high performance machines for data centers. To achieve short time to market, design flows must facilitate a much shortened time-to-product requirement. High-level modeling, architectural exploration and direct synthesis of design from high level description enable this design process. This book presents novel research techniques, algorithms,methodologies and experimental results for high level power estimation and power aware high-level synthesis. Readers will learn to apply such techniques to enable design flows resulting in shorter time to market and successful low power ASIC/FPGA design. Integrates power estimation and reduction for high level synthesis, with low-power, high-level design; Shows spec...

Excimer-laser-irradiation-induced effects in C60 films for photovoltaic applications

International Nuclear Information System (INIS)

Narayanan, K.L.; Yamaguchi, M.; Azuma, H.

2002-01-01

Thin films of fullerene C 60 deposited by the molecular-beam epitaxy method have been subjected to a 248 nm excimer laser for various timings. Reduction in the electrical resistance of the films and the spectral evolution of the D and G bands in the Raman spectra, due to the sharp tendency towards graphitization accompanied by an increasing level of structural disorder, are observed during laser irradiation. Based on the above results, an attempt has been carried out on these irradiated C 60 films to make a device sandwiched with n-type Si, and the photovoltaic parameters are reported as a function of the laser exposure times

Structuring of poly ether ether ketone by ArF excimer laser radiation in different atmospheres

International Nuclear Information System (INIS)

Feng, Y.; Gottmann, J.; Kreutz, E.W.

2003-01-01

Structuring of poly ether ether ketone (PEEK) by 193 nm ArF excimer laser radiation has been investigated. Experiments were carried out in different atmospheres (air, vacuum, Ar, O 2 ) in order to study its influence on the quality of the structures and the formation of the debris. Repetition rate makes little effect on the ablation rate and roughness of the structure in presence of any kind of atmosphere, indicating for the structuring of PEEK by ArF laser radiation a large window of processing. The roughness at the bottom of the structures and the morphology of the side walls are strongly affected by the properties of the atmosphere. The smallest roughness is achieved at 0.6 J/cm 2 for all kinds of processing gases. Debris around the structures can be diminished by structuring in vacuum. Plasma expansion speed has been measured by using high speed photography

High power communication satellites power systems study

International Nuclear Information System (INIS)

Josloff, A.T.; Peterson, J.R.

1994-01-01

This paper discusses a DOE-funded study to evaluate the commercial attractiveness of high power communication satellites and assesses the attributes of both conventional photovoltaic and reactor power systems. This study brings together a preeminent US Industry/Russian team to cooperate on the role of high power communication satellites in the rapidly expanding communications revolution. These high power satellites play a vital role in assuring availability of universally accessible, wide bandwidth communications, for high definition TV, super computer networks and other services. Satellites are ideally suited to provide the wide bandwidths and data rates required and are unique in the ability to provide services directly to the users. As new or relocated markets arise, satellites offer a flexibility that conventional distribution services cannot match, and it is no longer necessary to be near population centers to take advantage of the telecommunication revolution. The geopolitical implications of these substantially enhanced communications capabilities will be significant

308-nm excimer laser ablation of human cartilage

Science.gov (United States)

Prodoehl, John A.; Rhodes, Anthony L.; Meller, Menachem M.; Sherk, Henry H.

1993-07-01

The XeCl excimer laser was investigated as an ablating tool for human fibrocartilage and hyaline cartilage. Quantitative measurements were made of tissue ablation rates as a function of fluence in meniscal fibrocartilage and articular hyaline cartilage. A force of 1.47 Newtons was applied to an 800 micrometers fiber with the laser delivering a range of fluences (40 to 190 mj/mm2) firing at a frequency of 5 Hz. To assess the effect of repetition rate on ablation rate, a set of measurements was made at a constant fluence of 60 mj/mm2, with the repetition rate varying from 10 to 40 Hz. Histologic and morphometric analysis was performed using light microscopy. The results of these studies revealed that the ablation rate was directly proportional to fluence over the range tested. Fibrocartilage was ablated at a rate 2.56 times faster than hyaline cartilage at the maximum fluence tested. Repetition rate had no effect on the penetration per pulse. Adjacent tissue damage was noted to be minimal (10 - 70 micrometers ).

Safety, efficacy, predictability and stability of laser in situ keratomileusis (LASIK) with a 1000-Hz scanning spot excimer laser.

Science.gov (United States)

Khoramnia, Ramin; Salgado, Josefina P; Wuellner, Christian; Donitzky, Christof; Lohmann, Chris P; Winkler von Mohrenfels, Christoph

2012-09-01

To evaluate the safety, efficacy, predictability and stability of laser in situ keratomileusis (LASIK) with a 1000-Hz scanning spot excimer laser (Concept System 1000; WaveLight GmbH, Erlangen, Germany). LASIK was performed on twenty eyes with myopia or myopic astigmatism (mean spherical equivalent refraction: -3.97±1.72 dioptres (D); mean cylinder: -0.84±0.77 D) using a microkeratome for flap creation and the Concept System 1000 for photoablation. Patients were examined preoperatively as well as 1, 3 and 6 months after the treatment. Manifest sphere and cylinder, uncorrected (UCDVA) and best corrected (BCDVA) distance visual acuity, corneal topography and pachymetry were analysed. We observed no adverse events that might have been associated with the use of a repetition rate of 1000 Hz. All eyes maintained or had improved BCDVA at 6 months after treatment when compared to preoperative values. Six months after LASIK, UCDVA was 20/20 or better in 85% and 20/25 or better in 100% of the eyes. The spherical equivalent refraction was within ±0.50 D in 95% of the eyes at 6 months after surgery. The refraction stayed stable over time; 95% of the eyes changedLASIK with the prototype 1000-Hz excimer laser was safe, efficient and predictable. The postoperative refraction was stable over time. There were no specific clinical side-effects that might be associated with the use of such a high repetition rate. © 2011 The Authors. Acta Ophthalmologica © 2011 Acta Ophthalmologica Scandinavica Foundation.

Excimer-laser-induced permanent electrical conductivity in solid C60 films

International Nuclear Information System (INIS)

Ning, D.; Lou, Q.H.; Dong, J.X.; Wei, Y.R.

1996-01-01

After being irradiated in air by a XeCl (308 nm) excimer laser, the electrical conductivity of solid thin-film C 60 has been improved by more than six orders of magnitudes. The products resulting from laser irradiation of C 60 films have been investigated by Raman scattering and the onset of conductivity can be attributed to laser-induced oxygenation and disintegration of the fullerene. Irradiated by ∼40 ns laser pulses with different fluence, products with different microstructure were observed. At lower fluence, the Raman features of microcrystalline graphite and fullerene polymer were observed. At a fluence just below the ablation threshold (36 mJ/cm 2 ), the fullerene molecules in the film were disintegrated completely and transformed to amorphous graphite. (orig.). With 5 figs

CSTI High Capacity Power

International Nuclear Information System (INIS)

Winter, J.M.

1989-01-01

The SP-100 program was established in 1983 by DOD, DOE, and NASA as a joint program to develop the technology necessary for space nuclear power systems for military and civil application. During FY-86 and 87, the NASA SP-100 Advanced Technology Program was devised to maintain the momentum of promising technology advancement efforts started during Phase 1 of SP-100 and to strengthen, in key areas, the chances for successful development and growth capability of space nuclear reactor power systems for future space applications. In FY-88, the Advanced Technology Program was incorporated into NASA's new Civil Space Technology Initiative (CSTI). The CSTI Program was established to provide the foundation for technology development in automation and robotics, information, propulsion, and power. The CSTI High Capacity Power Program builds on the technology efforts of the SP-100 program, incorporates the previous NASA SP-100 Advanced Technology project, and provides a bridge to NASA Project Pathfinder. The elements of CSTI High Capacity Power development include Conversion Systems, Thermal Management, Power Management, System Diagnostics, and Environmental Interactions. Technology advancement in all areas, including materials, is required to assure the high reliability and 7 to 10 year lifetime demanded for future space nuclear power systems. The overall program will develop and demonstrate the technology base required to provide a wide range of modular power systems as well as allowing mission independence from solar and orbital attitude requirements. Several recent advancements in CSTI High Capacity power development will be discussed

High to ultra-high power electrical energy storage.

Science.gov (United States)

Sherrill, Stefanie A; Banerjee, Parag; Rubloff, Gary W; Lee, Sang Bok

2011-12-14

High power electrical energy storage systems are becoming critical devices for advanced energy storage technology. This is true in part due to their high rate capabilities and moderate energy densities which allow them to capture power efficiently from evanescent, renewable energy sources. High power systems include both electrochemical capacitors and electrostatic capacitors. These devices have fast charging and discharging rates, supplying energy within seconds or less. Recent research has focused on increasing power and energy density of the devices using advanced materials and novel architectural design. An increase in understanding of structure-property relationships in nanomaterials and interfaces and the ability to control nanostructures precisely has led to an immense improvement in the performance characteristics of these devices. In this review, we discuss the recent advances for both electrochemical and electrostatic capacitors as high power electrical energy storage systems, and propose directions and challenges for the future. We asses the opportunities in nanostructure-based high power electrical energy storage devices and include electrochemical and electrostatic capacitors for their potential to open the door to a new regime of power energy.

High average power solid state laser power conditioning system

International Nuclear Information System (INIS)

Steinkraus, R.F.

1987-01-01

The power conditioning system for the High Average Power Laser program at Lawrence Livermore National Laboratory (LLNL) is described. The system has been operational for two years. It is high voltage, high power, fault protected, and solid state. The power conditioning system drives flashlamps that pump solid state lasers. Flashlamps are driven by silicon control rectifier (SCR) switched, resonant charged, (LC) discharge pulse forming networks (PFNs). The system uses fiber optics for control and diagnostics. Energy and thermal diagnostics are monitored by computers

Latest result of PRK with excimer laser

Science.gov (United States)

Okamoto, Shinseiro; Okamoto, Michika

1996-05-01

We have in the last two years, performed PRK operation on over 300 human myopic eyes using ArF excimer laser with a Summit 'Omnimed' machine. For the initial 53 myopic eyes we treated, results were very good for those with correction less than minus 6 diopters. However, as previously reported, we also witnessed some regression for those eyes exceeding correction of more than minus 6 diopters. To counter such ill results of PRK we devised and suggested many new procedures for PRK with very good results. One such invention is the 'Okamoto-type' cooling machine for the cornea which reduces and stabilizes cornea temperature at 0 degrees Celsius while simultaneously bathing the cornea with special cooling fluid. After the operation, EGF, fibronectin and hexapeptide were administered using eyedrops. Soft contact lenses were used to protect the cornea, improve delivery of medication to the operated area, prevent infection and inflammation and also promote uniform and faster ephiterium regrowth. We were able to document very good post-operative results using this method, thereby giving us strong assurance that we have reached a significant milestone in PRK operation. Our report today covers post operative results of the 52 eyes we operated on and tracked for more than one year.

Influence of Selected Parameters of XeCl Excimer Laser System on Characteristics of Radiation Pulses

International Nuclear Information System (INIS)

Pokora, L.; Iwanejko, L.

1998-01-01

We present the dependences of energy and duration of radiation pulses as well as efficiency of XeCl laser on selected parameters of the laser system such as: C 2 capacitance, the separating inductance, L S , the distance between electrodes in laser's chamber, d K and also the supply voltage, U 0 , composition, and pressure of the active-medium mixture of gases. Results of numerical computations relate to a three-component mixture of gases, He-Xe-HCl, of the active medium of the excimer laser. (author)

The effect of excimer laser keratectomy on corneal glutathione peroxidase activities and aqueous humor selenium levels in rabbits.

Science.gov (United States)

Yis, Ozgür; Bilgihan, Ayşe; Bilgihan, Kamil; Yis, Nilgün Safak; Hasanreisoğlu, Berati

2002-06-01

The formation of free oxygen radicals has been demonstrated in the corneal tissue after 193 nm laser irradiation. Cornea has several defense mechanisms that protect against oxidative damage. One of them, glutathione peroxidase (GPx), catalyzes the destruction of hydrogen peroxide and lipid hydroperoxide. Selenium is a trace element which is incorporated into the selenoenzyme GPx. In the present study, the effect of excimer laser keratectomy on corneal GPx activities and aqueous humor selenium concentrations in rabbits was evaluated. Animals were divided into five groups, and all groups were compared: controls (group 1), after epithelial scraping (group 2), transepithelial photorefractive keratectomy(PRK; group 3), superficial traditional PRK (50 microm; group 4) and deep traditional PRK (100 microm; group 5). Corneal GPx activities were measured by a modification of the coupled assay procedure. Aqueous humor selenium concentrations were determined using hydride generation atomic absorption spectrometry. Corneal GPx activities were significantly lower only in group 5 ( P<0.05), and the selenium concentration in the aqueous humor did not change in any group. Deep corneal photoablation inhibits GPx enzyme activities in the cornea. Therefore, antioxidants may be useful in reducing free radical-mediated complications after excimer laser corneal photoablation.

Flexible power 90W to 120W ArF immersion light source for future semiconductor lithography

Science.gov (United States)

Burdt, R.; Thornes, J.; Duffey, T.; Bibby, T.; Rokitski, R.; Mason, E.; Melchior, J.; Aggarwal, T.; Haran, D.; Wang, J.; Rechtsteiner, G.; Haviland, M.; Brown, D.

2014-03-01

Semiconductor market demand for improved performance at lower cost continues to drive enhancements in excimer light source technologies. Increased output power, reduced variability in key light source parameters, and improved beam stability are required of the light source to support immersion lithography, multi-patterning, and 450mm wafer applications in high volume semiconductor manufacturing. To support future scanner needs, Cymer conducted a technology demonstration program to evaluate the design elements for a 120W ArFi light source. The program was based on the 90W XLR 600ix platform, and included rapid power switching between 90W and 120W modes to potentially support lot-to-lot changes in desired power. The 120W requirements also included improved beam stability in an exposure window conditionally reduced by 20%. The 120W output power is achieved by efficiency gains in system design, keeping system input power at the same level as the 90W XLR 600ix. To assess system to system variability, detailed system testing was conducted from 90W - 120W with reproducible results.

Gasochromic performance of WO{sub 3}-nanorod thin films fabricated with an ArF excimer laser

Energy Technology Data Exchange (ETDEWEB)

Yaacob, M. H. [RMIT University, Melbourne (Australia); Universiti Putra Malaysia, Selangor (Malaysia); Ou, J. Z.; Wlodarski, W. [RMIT University, Melbourne (Australia); Kim, C. S.; Lee, J. Y. [KAIST, Daejon (Korea, Republic of); Kim, Y. H. [KIST, Seoul (Korea, Republic of); Oh, C. M.; Dhakal, K. P.; Kim, J. Y.; Kang, J. H. [University of Incheon, Incheon (Korea, Republic of)

2012-02-15

Thin films with tungsten trioxide (WO{sub 3}) nanorods were fabricated by using an ArF pulsed laser deposition system. Because the ArF excimer laser operates at a very short wavelength of 193 nm, short enough to expect strong absorption of the photons in the semiconductor oxide targets, and because the clusters incoming to the substrates have high momentum, we could build thin films with good surface morphology. Highly homogeneous arrays of nanorods with sizes mostly in the range of 30 - 40 nm were observed. The absorbance response towards hydrogen (H{sub 2}) gas was investigated for a WO{sub 3} film coated with 25-A-thick palladium (Pd). The Pd/WO{sub 3}-nanorod thin films exhibited excellent gasochromic response when measured in the visible-NIR range (400 - 1000 nm). As low as 0.06% H{sub 2} concentration was clearly sensed. A significant reversible absorbance change and fast recovery (<2 min) were observed when the films were exposed to H{sub 2} at different concentrations.

Aqueous transforming growth factor-beta-I levels in rabbit eyes after excimer laser photoablation.

Science.gov (United States)

Bilgihan, K; Gürelik, G; Okur, H; Bilgihan, A; Hasanreisoglu, B; Imir, T

1997-01-01

Transforming growth factor beta (TGF-beta) plays an important role in anterior segment wound healing, by controlling the cell proliferation and differentiation, angiogenesis, extracellular matrix composition and mediating the immunosuppressive properties of the aqueous humor. The present study was undertaken to clarify the possible changes of aqueous humor TGF-betaI levels after excimer laser photoablation. Twenty-eight New Zealand rabbits were divided into four groups of 7 rabbits each. Group 1 served as control, the central 7 mm of corneal epithelium was removed in groups 2, 3 and 4. We performed 50-microm corneal photoablation in group 3, and 100-microm ablation in group 4. After 48 h we measured the TGF-betaI levels of the aqueous humor by ELISA method. The mean TGF-betaI value of the aqueous humor was found to be 162.94+/-13.73 pg/ml in the control group. Mechanical deepithelialization did not change the TGF-betaI levels of the aqueous humor (p > 0.05). There was no significant difference between the 50-microm photoablated group and the controls (p > 0.05), but the TGF-betaI levels of the 100-microm photoablated group were found to be significantly higher than those of both the control group and 50-microm photoablated group (p < 0.05). Many factors and cytokines may induce corneal haze and myopic regression after excimer laser photoablation; our study demonstrated that TGF-betaI is one of these factors and there is a positive correlation between the depth of corneal photoablation and aqueous TGF-betaI concentrations.

Microstructures induced by excimer laser surface melting of the SiC{sub p}/Al metal matrix composite

Energy Technology Data Exchange (ETDEWEB)

Qian, D.S., E-mail: Daishu.qian@postgrad.manchester.ac.uk; Zhong, X.L.; Yan, Y.Z.; Hashimoto, T.; Liu, Z.

2017-08-01

Highlights: • Microstructural analysis of the excimer laser-melted SiC{sub p}/AA2124;. • Analytical, FEM, and SPH simulation of the laser-material interaction;. • Mechanism of the formation of the laser-induced microstructure. - Abstract: Laser surface melting (LSM) was carried out on the SiC{sub p}/Al metal matrix composite (MMC) using a KrF excimer laser with a fluence of 7 J/cm{sup 2}. The re-solidification microstructure was characterized using scanning electron microscopy (SEM), transmission electron microscopy (TEM) equipped with energy dispersive X-ray detector, and X-ray diffraction (XRD) analysis. It was found that a 2.5 μm thick melted layer was formed in the near-surface region, in which dissolution of the intermetallics and removal of the SiC particles occurred. The thermal and material response upon laser irradiation was simulated using three models, i.e. analytical model, finite element model (FEM) and smoothed-particle hydrodynamics (SPH) model. The effect of SiC particles on the LSM process, the mechanism of the SiC removal and the re-solidification microstructures in the melted layer were discussed. The simulation results were in good agreement with the experimental results and contributed to the generic understanding of the re-solidification microstructures induced by ns-pulsed lasers.

80 A/cm2 electron beams from metal targets irradiated by KrCl and XeCl excimer lasers

Science.gov (United States)

Beloglazov, A.; Martino, M.; Nassisi, V.

1996-05-01

Due to the growing demand for high-current and long-duration electron-beam devices, laser electron sources were investigated in our laboratory. Experiments on electron-beam generation and propagation from aluminium and copper targets illuminated by XeCl (308 nm) and KrCl (222 nm) excimer lasers, were carried out under plasma ignition due to laser irradiation. This plasma supplied a spontaneous accelerating electric field of about 370 kV/m without an external accelerating voltage. By applying the modified one-dimensional Poisson equation, we computed the expected current and we also estimated the plasma concentration during the accelerating process. At 40 kV of accelerating voltage, an output current pulse of about 80 A/cm2 was detected from an Al target irradiated by the shorter wavelength laser.

Preparation of PZT thin films on YBCO electrodes by KrF excimer laser ablation technique

International Nuclear Information System (INIS)

Kurogi, H.; Yamagata, Y.; Ebihara, K.

1998-01-01

Pb(Zr X Ti 1-X )O 3 (PZT) films have excellent ferroelectric, optical, piezoelectric, and pyroelectric properties. We prepared PZT thin films by the excimer laser ablation technique. A pulsed KrF excimer laser (Lambda Physik LPX305icc, pulse duration of 25 ns, λ=248 nm, 850 mJ Max.) was used to ablate the bulk targets. We investigated the influence of bottom electrode materials on the characteristics of the PZT thin films prepared on Pt and YBCO underlayers. The X-ray diffraction (XRD) patterns showed that the PZT films prepared with a laser fluence of 2 Jcm -2 on YBCO/MgO(100) substrate at a wide temperature range of 550-680 C have a perovskite (001) structure. At the same laser fluence, the PZT films prepared on Pt/MgO(100) substrate have a perovskite (001) structure only at 650 C. The polarization-electric field (P-E) characteristics and fatigue properties of PZT thin films were measured by the Sawyer-Tower circuit. The remnant polarization and coercive field have been found to be P r =15 μC cm -2 , 30 μC cm -2 and E c =200 kV cm -1 , 100 kV cm -1 for Au/PZT/Pt/MgO and Au/PZT/YBCO/MgO correspondingly. The remnant polarization of Au/PZT/YBCO/MgO thin film was reduced to one-half after about 10 8 cycles of switching. (orig.)

High power communication satellites power systems study

Science.gov (United States)

Josloff, Allan T.; Peterson, Jerry R.

1995-01-01

This paper discusses a planned study to evaluate the commercial attractiveness of high power communication satellites and assesses the attributes of both conventional photovoltaic and reactor power systems. These high power satellites can play a vital role in assuring availability of universally accessible, wide bandwidth communications, for high definition TV, super computer networks and other services. Satellites are ideally suited to provide the wide bandwidths and data rates required and are unique in the ability to provide services directly to the users. As new or relocated markets arise, satellites offer a flexibility that conventional distribution services cannot match, and it is no longer necessary to be near population centers to take advantage of the telecommunication revolution. The geopolitical implications of these substantially enhanced communications capabilities can be significant.

Thermodynamic and Kinetic Behavior of the Polystyrene/Poly(vinyl methyl ether) Blend as Studied by Excimer Fluorescence.

Science.gov (United States)

1986-01-02

AD-A±63 895 THERMODYNAMIC AND KINETIC BEHAVIOR OF THE / POLYSTYRENE/POLY(YINYL METHYL E..(U) STANFORD UNIY CALIFDEPT OF CHEMICAL ENGINEERING C N...Polystyrene/Poly(vinyl methyl ether) Blend 7. DEcFRMN 81 toOR 30USptE8 00~ as Studied by Excimer Fluorescence 6 EFRIGOG EOTNME *AUTHOR() a. CONTRACT OR GRANT...werea fondoare ihemoriisof * ~ Ex e sp fluodecositionsdu to deud Gen e and hoog Pinus Florsneis shownhase migrationprocSECURITY CLASIFICTIO OFd

High power microwaves

CERN Document Server

Benford, James; Schamiloglu, Edl

2016-01-01

Following in the footsteps of its popular predecessors, High Power Microwaves, Third Edition continues to provide a wide-angle, integrated view of the field of high power microwaves (HPMs). This third edition includes significant updates in every chapter as well as a new chapter on beamless systems that covers nonlinear transmission lines. Written by an experimentalist, a theorist, and an applied theorist, respectively, the book offers complementary perspectives on different source types. The authors address: * How HPM relates historically and technically to the conventional microwave field * The possible applications for HPM and the key criteria that HPM devices have to meet in order to be applied * How high power sources work, including their performance capabilities and limitations * The broad fundamental issues to be addressed in the future for a wide variety of source types The book is accessible to several audiences. Researchers currently in the field can widen their understanding of HPM. Present or pot...

Simultaneous determinations of U-Pb age and REE abundances for zircons using AfF excimer laser ablation-ICPMS

International Nuclear Information System (INIS)

Iizuka, Tsuyoshi; Hirata, Takafumi

2004-01-01

Using a laser-ablation-inductively coupled plasma mass spectrometer (LA-ICPMS), U-Pb age and rare earth element (REE) abundances have been determined simultaneously from a single 20 μm ablation pit of zircon. The laser ablation system utilizing 193 nm wave-length ArF excimer laser produces stable and reproducible signal intensities resulted in good precisions on measurements of element concentrations and isotopic ratios. Because of the higher energy density of the deep ultra-violet laser beam, ablation fractionation between Pb and U were reduced even with the prolonged ablation, and thus accuracy of Pb-U age was improved significantly. A chicane-type ion lens system was applied to a quadrupole-based ICPMS instrument. With the chicane ion lens, higher elemental sensitivity (4 times or light mass range and 3 times for mid to heavy mass range) and lower white background ( 238 U- 206 Pb ages for Nancy standard zircon (Nancy 91500), SHRIMP calibration standard zircon (SL13) and Antarctic zircon (PMA7) obtained in this study were 1064 ± 24 Ma, 569 ± 78 Ma and 2438 ± 101 Ma (2-sigma), respectively. Relative age differences from previous reports were 0.2%, 0.4% and 3.2% respectively, demonstrative of high reliability of the method. The REE abundances in zircon samples were calibrated using a NIST 610 glass standard reference material. The resulting REE abundance data for zircons (Nancy 91500 and SL13) show good agreement with those for literature values within the analytical precision of ∼20%. The matrix effect that may occur between the synthetic glass standard and zircon crystals is obviously smaller than the precision and thus negligible for this precision levels. The data presented here demonstrate clearly that the combination of ArF excimer laser an ICPMS equipped with the chicane ion lens has a potential to become a significant tool for zircon geochemistry. (author)

High Power High Efficiency Diode Laser Stack for Processing

Science.gov (United States)

Gu, Yuanyuan; Lu, Hui; Fu, Yueming; Cui, Yan

2018-03-01

High-power diode lasers based on GaAs semiconductor bars are well established as reliable and highly efficient laser sources. As diode laser is simple in structure, small size, longer life expectancy with the advantages of low prices, it is widely used in the industry processing, such as heat treating, welding, hardening, cladding and so on. Respectively, diode laser could make it possible to establish the practical application because of rectangular beam patterns which are suitable to make fine bead with less power. At this power level, it can have many important applications, such as surgery, welding of polymers, soldering, coatings and surface treatment of metals. But there are some applications, which require much higher power and brightness, e.g. hardening, key hole welding, cutting and metal welding. In addition, High power diode lasers in the military field also have important applications. So all developed countries have attached great importance to high-power diode laser system and its applications. This is mainly due their low performance. In this paper we will introduce the structure and the principle of the high power diode stack.

Boron distribution in silicon after multiple pulse excimer laser annealing

International Nuclear Information System (INIS)

Monakhov, E.V.; Svensson, B.G.; Linnarsson, M.K.; La Magna, A.; Italia, M.; Privitera, V.; Fortunato, G.; Cuscuna, M.; Mariucci, L.

2005-01-01

We have studied B redistribution in Si after excimer laser annealing (ELA) with multiple laser pulses. B was implanted with energies of 1 and 10 keV and doses of 1x10 14 and 1x10 15 cm -2 . ELA with the number of pulses from 1 to 100 was performed at room temperature and 450 deg. C in vacuum. Irrespective of the implantation parameters and the ELA conditions used, a pile-up in the B concentration is observed near the maximum melting depth after ten pulses of ELA. Moreover, a detailed study has revealed that B accumulates at the maximum melt depth gradually with the number of ELA pulses. Besides, an increase in the carrier concentration is observed at the maximum melt depth, suggesting electrical activity of the accumulated B. Formation of Si-B complexes and vacancy accumulation during multiple ELA are discussed as possible mechanisms for the B build-up

High power CW linac in PNC

International Nuclear Information System (INIS)

Toyama, S.; Wang, Y.L.; Emoto, T.

1994-01-01

Power Reactor and Nuclear Fuel Development Corporation (PNC) is developing a high power electron linac for various applications. The electron beam is accelerated in CW operation to get maximum beam current of 100 mA and energy of 10 MeV. Crucial components such as a high power L-band klystron and a high power traveling wave resonant ring (TWRR) accelerator guides were designed and manufactured and their performance were examined. These design and results from the recent high power RF tests were described in this paper. (author)

Dopant redistribution and electrical activation in silicon following ultra-low energy boron implantation and excimer laser annealing

International Nuclear Information System (INIS)

Whelan, S.; La Magna, A.; Privitera, V.; Mannino, G.; Italia, M.; Bongiorno, C.; Fortunato, G.; Mariucci, L.

2003-01-01

Excimer laser annealing (ELA) of ultra-low-energy (ULE) B-ion implanted Si has been performed. High-resolution transmission electron microscopy has been used to assess the as-implanted damage and the crystal recovery following ELA. The electrical activation and redistribution of B in Si during ELA has been investigated as a function of the laser energy density (melted depth), the implant dose, and the number of laser pulses (melt time). The activated and retained dose has been evaluated with spreading resistance profiling and secondary ion mass spectrometry. A significant amount of the implanted dopant was lost from the sample during ELA. However, the dopant that was retained in crystal material was fully activated following rapid resolidification. At an atomic concentration below the thermodynamic limit, the activation efficiency (dose activated/dose implanted into Si material) was a constant for a fixed melt depth, irrespective of the dose implanted and hence the total activated dose was raised as the implant dose was increased. The electrical activation was increased for high laser energy density annealing when the dopant was redistributed over a deeper range

Enhancement of VUV emission from a coaxial xenon excimer ultraviolet lamp driven by distorted bipolar square voltages

Energy Technology Data Exchange (ETDEWEB)

Jou, S.Y.; Hung, C.T.; Chiu, Y.M.; Wu, J.S. [Department of Mechanical Engineering, National Chiao Tung University, Hsinchu (China); Wei, B.Y. [High-Efficiency Gas Discharge Lamps Group, Material and Chemical Research Laboratories, Hsinchu (China)

2011-12-15

Enhancement of vacuum UV emission (172 nm VUV) from a coaxial xenon excimer UV lamp (EUV) driven by distorted 50 kHz bipolar square voltages, as compared to that by sinusoidal voltages, is investigated numerically in this paper. A self-consistent radial one-dimensional fluid model, taking into consideration non-local electron energy balance, is employed to simulate the discharge physics and chemistry. The discharge is divided into two three-period portions; these include: the pre-discharge, the discharge (most intense at 172 nm VUV emission) and the post-discharge periods. The results show that the efficiency of VUV emission using the distorted bipolar square voltages is much greater than when using sinusoidal voltages; this is attributed to two major mechanisms. The first is the much larger rate of change of the voltage in bipolar square voltages, in which only the electrons can efficiently absorb the power in a very short period of time. Energetic electrons then generate a higher concentration of metastable (and also excited dimer) xenon that is distributed more uniformly across the gap, for a longer period of time during the discharge process. The second is the comparably smaller amount of ''wasted'' power deposition by Xe{sup +}{sub 2} in the post-discharge period, as driven by distorted bipolar square voltages, because of the nearly vanishing gap voltage caused by the shielding effect resulting from accumulated charges on both dielectric surfaces (copyright 2011 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

Powering the High-Luminosity Triplets

Science.gov (United States)

Ballarino, A.; Burnet, J. P.

The powering of the magnets in the LHC High-Luminosity Triplets requires production and transfer of more than 150 kA of DC current. High precision power converters will be adopted, and novel High Temperature Superconducting (HTS) current leads and MgB2 based transfer lines will provide the electrical link between the power converters and the magnets. This chapter gives an overview of the systems conceived in the framework of the LHC High-Luminosity upgrade for feeding the superconducting magnet circuits. The focus is on requirements, challenges and novel developments.

Excimer laser-assisted anterior lamellar keratoplasty for keratoconus, corneal problems after laser in situ keratomileusis, and corneal stromal opacities.

Science.gov (United States)

Bilgihan, Kamil; Ozdek, Sengül C; Sari, Ayça; Hasanreisoğlu, Berati

2006-08-01

To evaluate excimer laser-assisted anterior lamellar keratoplasty to augment thin corneas as in keratoconus ( .05). This technique presents a different modality for the treatment of keratoconus, post-LASIK corneal problems, and other corneal stromal opacities with anterior lamellar keratoplasty. Additional studies with more patients and longer follow-up will help determine the role of this technique as a substitute for penetrating keratoplasty in these patients.

Review of Power System Stability with High Wind Power Penetration

DEFF Research Database (Denmark)

Hu, Rui; Hu, Weihao; Chen, Zhe

2015-01-01

analyzing methods and stability improvement approaches. With increasing wind power penetration, system balancing and the reduced inertia may cause a big threaten for stable operation of power systems. To mitigate or eliminate the wind impacts for high wind penetration systems, although the practical......This paper presents an overview of researches on power system stability with high wind power penetration including analyzing methods and improvement approaches. Power system stability issues can be classified diversely according to different considerations. Each classified issue has special...... and reliable choices currently are the strong outside connections or sufficient reserve capacity constructions, many novel theories and approaches are invented to investigate the stability issues, looking forward to an extra-high penetration or totally renewable resource based power systems. These analyzing...

Preparation of PZT thin films on YBCO electrodes by KrF excimer laser ablation technique

Energy Technology Data Exchange (ETDEWEB)

Kurogi, H; Yamagata, Y; Ebihara, K [Kumamoto Univ. (Japan). Dept. of Electr. Eng. and Comput. Sci.; Inoue, N [Kyushu Electric Power Co., Inc., Suizenji, 1-6-36, Kumamoto 862 (Japan)

1998-03-01

Pb(Zr{sub X}Ti{sub 1-X})O{sub 3} (PZT) films have excellent ferroelectric, optical, piezoelectric, and pyroelectric properties. We prepared PZT thin films by the excimer laser ablation technique. A pulsed KrF excimer laser (Lambda Physik LPX305icc, pulse duration of 25 ns, {lambda}=248 nm, 850 mJ Max.) was used to ablate the bulk targets. We investigated the influence of bottom electrode materials on the characteristics of the PZT thin films prepared on Pt and YBCO underlayers. The X-ray diffraction (XRD) patterns showed that the PZT films prepared with a laser fluence of 2 Jcm{sup -2} on YBCO/MgO(100) substrate at a wide temperature range of 550-680 C have a perovskite (001) structure. At the same laser fluence, the PZT films prepared on Pt/MgO(100) substrate have a perovskite (001) structure only at 650 C. The polarization-electric field (P-E) characteristics and fatigue properties of PZT thin films were measured by the Sawyer-Tower circuit. The remnant polarization and coercive field have been found to be P{sub r}=15 {mu}C cm{sup -2}, 30 {mu}C cm{sup -2} and E{sub c}=200 kV cm{sup -1}, 100 kV cm{sup -1} for Au/PZT/Pt/MgO and Au/PZT/YBCO/MgO correspondingly. The remnant polarization of Au/PZT/YBCO/MgO thin film was reduced to one-half after about 10{sup 8} cycles of switching. (orig.) 7 refs.

[Excimer laser therapy of alopecia areata--side-by-side evaluation of a representative area].

Science.gov (United States)

Raulin, Christian; Gündogan, Cüneyt; Greve, Bärbel; Gebert, Susanne

2005-07-01

We report for the first time on hair regrowth in alopecia areata of the scalp achieved with the 308-nm xenon-chloride excimer laser in a prospective side-by-side trial. The alopecia areata had shown progression over a period of three years, and various treatments had not been effective. Out of a number of affected areas, one representative lesion was chosen; one half of it was treated, the other half remained untreated. After 27 sessions (200 - 4000 mJ/cm2, cumulative dose 52.6 J/cm2) over 3 months, only the treated area showed hair growth; which suggests that this was most probably not a spontaneous remission.

Autonomously managed high power systems

International Nuclear Information System (INIS)

Weeks, D.J.; Bechtel, R.T.

1985-01-01

The need for autonomous power management capabilities will increase as the power levels of spacecraft increase into the multi-100 kW range. The quantity of labor intensive ground and crew support consumed by the 9 kW Skylab cannot be afforded in support of a 75-300 kW Space Station or high power earth orbital and interplanetary spacecraft. Marshall Space Flight Center is managing a program to develop necessary technologies for high power system autonomous management. To date a reference electrical power system and automation approaches have been defined. A test facility for evaluation and verification of management algorithms and hardware has been designed with the first of the three power channel capability nearing completion

ICAN: High power neutral beam generation

International Nuclear Information System (INIS)

Moustaizis, S.D.; Lalousis, P.; Perrakis, K.; Auvray, P.; Larour, J.; Ducret, J.E.; Balcou, P.

2015-01-01

During the last few years there is an increasing interest on the development of alternative high power new negative ion source for Tokamak applications. The proposed new neutral beam device presents a number of advantages with respect to: the density current, the acceleration voltage, the relative compact dimension of the negative ion source, and the coupling of a high power laser beam for photo-neutralization of the negative ion beam. Here we numerically investigate, using a multi- fluid 1-D code, the acceleration and the extraction of high power ion beam from a Magnetically Insulated Diode (MID). The diode configuration will be coupled to a high power device capable of extracting a current up to a few kA with an accelerating voltage up to MeV. An efficiency of up to 92% of the coupling of the laser beam, is required in order to obtain a high power, up to GW, neutral beam. The new high energy, high average power, high efficiency (up to 30%) ICAN fiber laser is proposed for both the plasma generation and the photo-neutralizer configuration. (authors)

158. Extracción quirúrgica de electrodos de marcapasos y desfibrilador asistida con láser excimer

Directory of Open Access Journals (Sweden)

V.X. Mosquera Rodríguez

2012-04-01

Conclusiones: El láser Excimer se presenta como una alternativa eficaz para la extracción de electrodos intravasculares con resultados excelentes en nuestra serie, permitiendo tratar algunos pacientes que difícilmente podrían ser abordados con otras técnicas existentes. El riesgo de complicaciones cardiovasculares mayores exige que la técnica sea efectuada bajo anestesia general en un quirófano habilitado para cirugía cardíaca.

High average power supercontinuum sources

Indian Academy of Sciences (India)

The physical mechanisms and basic experimental techniques for the creation of high average spectral power supercontinuum sources is briefly reviewed. We focus on the use of high-power ytterbium-doped fibre lasers as pump sources, and the use of highly nonlinear photonic crystal fibres as the nonlinear medium.

High Temperature, High Power Piezoelectric Composite Transducers

Science.gov (United States)

Lee, Hyeong Jae; Zhang, Shujun; Bar-Cohen, Yoseph; Sherrit, StewarT.

2014-01-01

Piezoelectric composites are a class of functional materials consisting of piezoelectric active materials and non-piezoelectric passive polymers, mechanically attached together to form different connectivities. These composites have several advantages compared to conventional piezoelectric ceramics and polymers, including improved electromechanical properties, mechanical flexibility and the ability to tailor properties by using several different connectivity patterns. These advantages have led to the improvement of overall transducer performance, such as transducer sensitivity and bandwidth, resulting in rapid implementation of piezoelectric composites in medical imaging ultrasounds and other acoustic transducers. Recently, new piezoelectric composite transducers have been developed with optimized composite components that have improved thermal stability and mechanical quality factors, making them promising candidates for high temperature, high power transducer applications, such as therapeutic ultrasound, high power ultrasonic wirebonding, high temperature non-destructive testing, and downhole energy harvesting. This paper will present recent developments of piezoelectric composite technology for high temperature and high power applications. The concerns and limitations of using piezoelectric composites will also be discussed, and the expected future research directions will be outlined. PMID:25111242

A 380 V High Efficiency and High Power Density Switched-Capacitor Power Converter using Wide Band Gap Semiconductors

DEFF Research Database (Denmark)

Fan, Lin; Knott, Arnold; Jørgensen, Ivan Harald Holger

2018-01-01

. This paper presents such a high voltage low power switched-capacitor DC-DC converter with an input voltage upto 380 V (compatible with rectified European mains) and an output power experimentally validated up to 21.3 W. The wideband gap semiconductor devices of GaN switches and SiC diodes are combined...... to compose the proposed power stage. Their switching and loss characteristics are analyzed with transient waveforms and thermal images. Different isolated driving circuits are compared and a compact isolated halfbridge driving circuit is proposed. The full-load efficiencies of 98.3% and 97.6% are achieved......State-of-the-art switched-capacitor DC-DC power converters mainly focus on low voltage and/or high power applications. However, at high voltage and low power levels, new designs are anticipated to emerge and a power converter that has both high efficiency and high power density is highly desirable...

Impact of Angioscopic Evaluation for Femoropopliteal In-Stent Restenosis Before and After Excimer Laser Atherectomy.

Science.gov (United States)

Idemoto, Akiko; Okamoto, Naotaka; Tanaka, Akihiro; Mori, Naoki; Nakamura, Daisuke; Yano, Masamichi; Makino, Nobuhiko; Egami, Yasuyuki; Shutta, Ryu; Tanouchi, Jun; Nishino, Masami

2017-07-01

In-stent restenosis (ISR) is a prevalent problem following stenting of femoropopliteal lesions. A potential novel treatment modality for ISR including excimer laser atherectomy (ELA) has become available. We performed ELA for in-stent chronic total occlusion (CTO) of femoropopliteal lesions and evaluated lesion morphology before and after ELA by angioscopy in 2 patients. The angioscopic findings clearly showed removal of in-stent thrombi after ELA. Thus, ELA may be effective for in-stent CTO of femoropopliteal lesions. This is the first report describing the direct visualization of ELA effect for vaporization of thrombi in femoropopliteal in-stent lesions by angioscopy.

Fault analysis and strategy of high pulsed power supply for high power laser

International Nuclear Information System (INIS)

Liu Kefu; Qin Shihong; Li Jin; Pan Yuan; Yao Zonggan; Zheng Wanguo; Guo Liangfu; Zhou Peizhang; Li Yizheng; Chen Dehuai

2001-01-01

according to the requirements of driving flash-lamp, a high pulsed power supply (PPS) based on capacitors as energy storage elements is designed. The author analyzes in detail the faults of high pulsed power supply for high power laser. Such as capacitor internal short-circuit, main bus breakdown to ground, flashlamp sudden short or break. The fault current and voltage waveforms were given by circuit simulations. Based on the analysis and computation, the protection strategy with the fast fuse and ZnO was put forward, which can reduce the damage of PPS to the lower extent and provide the personnel safe and collateral property from the all threats. The preliminary experiments demonstrated that the design of the PPS can satisfy the project requirements

High Power Density Power Electronic Converters for Large Wind Turbines

DEFF Research Database (Denmark)

Senturk, Osman Selcuk

. For these VSCs, high power density is required due to limited turbine nacelle space. Also, high reliability is required since maintenance cost of these remotely located wind turbines is quite high and these turbines operate under harsh operating conditions. In order to select a high power density and reliability......In large wind turbines (in MW and multi-MW ranges), which are extensively utilized in wind power plants, full-scale medium voltage (MV) multi-level (ML) voltage source converters (VSCs) are being more preferably employed nowadays for interfacing these wind turbines with electricity grids...... VSC solution for wind turbines, first, the VSC topology and the switch technology to be employed should be specified such that the highest possible power density and reliability are to be attained. Then, this qualitative approach should be complemented with the power density and reliability...

Radiofrequency initiation and radiofrequency sustainment of laser initiated seeded high pressure plasma

International Nuclear Information System (INIS)

Paller, Eric S.; Scharer, John E.; Akhtar, Kamran; Kelly, Kurt; Ding, Guowen

2001-01-01

We examine radiofrequency initiation of high pressure(1-70 Torr) inductive plasma discharges in argon, nitrogen, air and organic seed gas mixtures. Millimeter wave interferometry, optical emission and antenna wave impedance measurements for double half-turn helix and helical inductive antennas are used to interpret the rf/plasma coupling, measure the densities in the range of 10 12 cm -3 and analyze the ionization and excited states of the gas mixtures. We have also carried out 193 nm excimer laser initiation of an organic gas seed plasma which is sustained at higher pressures(150 Torr) by radiofrequency coupling at 2.8 kW power levels

The Improvement of Electrical Characteristics of Pt/Ti Ohmic Contacts to Ga-Doped ZnO by Homogenized KrF Pulsed Excimer Laser Treatment

Science.gov (United States)

Oh, Min-Suk

2018-04-01

We investigated the effect of KrF excimer laser surface treatment on Pt/Ti ohmic contacts to Ga-doped n-ZnO ( N d = 4.3 × 1017 cm-3). The treatment of the n-ZnO surfaces by laser irradiation greatly improved the electrical characteristics of the metal contacts. The Pt/Ti ohmic layer on the laser-irradiated n-ZnO showed specific contact resistances of 2.5 × 10-4 ˜ 4.8 × 10-4 Ω cm2 depending on the laser energy density and gas ambient, which were about two orders of magnitude lower than that of the as-grown sample, 8.4 × 10-2 Ω cm2. X-ray photoelectron spectroscopy and photoluminescence measurements showed that the KrF excimer laser treatments increased the electron concentration near the surface region of the Ga-doped n-ZnO due to the preferential evaporation of oxygen atoms from the ZnO surface by the laser-induced dissociation of Zn-O bonds.

A high-power versatile wireless power transfer for biomedical implants.

Science.gov (United States)

Jiang, Hao; Zhang, Jun Min; Liou, Shy Shenq; Fechter, Richard; Hirose, Shinjiro; Harrison, Michael; Roy, Shuvo

2010-01-01

Implantable biomedical actuators are highly desired in modern medicine. However, how to power up these biomedical implants remains a challenge since most of them need more than several hundreds mW of power. The air-core based radio-frequency transformer (two face-to-face inductive coils) has been the only non-toxic and non-invasive power source for implants for the last three decades [1]. For various technical constraints, the maximum delivered power is limited by this approach. The highest delivered power reported is 275 mW over 1 cm distance [2]. Also, the delivered power is highly vulnerable to the coils' geometrical arrangement and the electrical property of the medium around them. In this paper, a novel rotating-magnets based wireless power transfer that can deliver ∼10 W over 1 cm is demonstrated. The delivered power is significantly higher than the existing start-of-art. Further, the new method is versatile since there is no need to have the impedance matching networks that are highly susceptible to the operating frequency, the coil arrangement and the environment.

Unscheduled DNA synthesis in human skin after in vitro ultraviolet-excimer laser ablation

International Nuclear Information System (INIS)

Green, H.A.; Margolis, R.; Boll, J.; Kochevar, I.E.; Parrish, J.A.; Oseroff, A.R.

1987-01-01

DNA damage repaired by the excision repair system and measured as unscheduled DNA synthesis (UDS) was assessed in freshly excised human skin after 193 and 248 nm ultraviolet (UV)-excimer laser ablative incisions. Laser irradiation at 248 nm induced DNA damage throughout a zone of cells surrounding the ablated and heat-damaged area. In contrast, with 193 nm irradiation UDS was not detected in cells adjacent to the ablated area, even though DNA strongly absorbs this wavelength. Our results suggest that the lack of UDS after 193 nm irradiation is due to: ''shielding'' of DNA by the cellular interstitium, membrane, and cytoplasm, DNA damage that is not repaired by excision repair, or thermal effects that either temporarily or permanently inhibit the excision repair processes

Pulsed high-power beams

International Nuclear Information System (INIS)

Reginato, L.L.; Birx, D.L.

1988-01-01

The marriage of induction linac technology with nonlinear magnetic modulators has produced some unique capabilities. It is now possible to produce short-pulse electron beams with average currents measured in amperes, at gradients approaching 1-MeV/m, and with power efficiencies exceeding 50%. This paper reports on a 70-MeV, 3-kA induction accelerator (ETA II) constructed at the Lawrence Livermore National Laboratory that incorporates the pulse technology concepts that have evolved over the past several years. The ETA II is a linear induction accelerator and provides a test facility for demonstration of the high-average-power components and high-brightness sources used in such accelerators. The pulse drive of the accelerator is based on state-of-the-art magnetic pulse compressors with very high peak-power capability, repetition rates exceeding 1 kHz, and excellent reliability

A battery-powered high-current power supply for superconductors

CERN Document Server

Wake, M; Suda, K

2002-01-01

Since superconductors do not require voltages, a high-current power supply could run with low power if the voltage is sufficiently reduced. Even a battery-powered power supply could give as much as 2,000A for a superconductor. To demonstrate this hypothesis, a battery-powered 2,000A power supply was constructed. It uses an IGBT chopper and Schottky diode together with a specially arranged transformer to produce a high current with low voltage. Testing of 2,000A operation was performed for about 1.5 hr using 10 car batteries. Charging time for this operation was 8 hr. Ramping control was smooth and caused no trouble. Although the IGBT frequency ripple of 16.6 kHz was easily removed using a passive filter, spike noise remained in the output voltage. This ripple did not cause any trouble in operating a pancake-type inductive superconducting load. (author)

High-field, high-density tokamak power reactor

International Nuclear Information System (INIS)

Cohn, D.R.; Cook, D.L.; Hay, R.D.; Kaplan, D.; Kreischer, K.; Lidskii, L.M.; Stephany, W.; Williams, J.E.C.; Jassby, D.L.; Okabayashi, M.

1977-11-01

A conceptual design of a compact (R 0 = 6.0 m) high power density (average P/sub f/ = 7.7 MW/m 3 ) tokamak demonstration power reactor has been developed. High magnetic field (B/sub t/ = 7.4 T) and moderate elongation (b/a = 1.6) permit operation at the high density (n(0) approximately 5 x 10 14 cm -3 ) needed for ignition in a relatively small plasma, with a spatially-averaged toroidal beta of only 4%. A unique design for the Nb 3 Sn toroidal-field magnet system reduces the stress in the high-field trunk region, and allows modularization for simpler disassembly. The modest value of toroidal beta permits a simple, modularized plasma-shaping coil system, located inside the TF coil trunk. Heating of the dense central plasma is attained by the use of ripple-assisted injection of 120-keV D 0 beams. The ripple-coil system also affords dynamic control of the plasma temperature during the burn period. A FLIBE-lithium blanket is designed especially for high-power-density operation in a high-field environment, and gives an overall tritium breeding ratio of 1.05 in the slowly pumped lithium

Excimer Pumped Pulsed Tunable Dye Laser

Science.gov (United States)

Littman, Michael G.

1988-06-01

It has been recently shown and reported for the first time at this meeting, that Excimer pumping of a single-mode, short-cavity, grazing-incidence, longitudinally-pumped pulsed dye laser is feasible. In this paper the key concepts upon which this latest development is based are presented and are in a somewhat unusual form. This manuscript describes five specific dye laser examples. The five examples represent a progression from the simplest type of dye laser to the single-mode version mentioned above. The examples thus serve as a tutorial introduction to potential users of dye lasers. The article is organized into five sections or STEPS, each of which describes a different pulsed dye laser. Since the subtle points about dye lasers are best appreciated only after one actually attempts to build a working model, a PROCEDURES category is included in which details about the construction of the particular form of laser are given. As one reads through this category, think of it as looking over the shoulder of the laser builder. The NOTES category which follows is a brief but essential discussion explaining why various components and procedures are used, as well as how laser performance specifications are obtained. This subsection can he viewed as a discussion with the laser builder concerning the reasons for specific actions and choices made in the assembly of the example laser. The last category contains COMMENTS which provide additional related information pertaining to the example laser that goes beyond the earlier annotated discussion. If you like, these are the narrator's comments. At the end of the article, after the five sequential forms of the laser have been presented, there is a brief summation.

Consistent comparison of angle Kappa adjustment between Oculyzer and Topolyzer Vario topography guided LASIK for myopia by EX500 excimer laser.

Science.gov (United States)

Sun, Ming-Shen; Zhang, Li; Guo, Ning; Song, Yan-Zheng; Zhang, Feng-Ju

2018-01-01

To evaluate and compare the uniformity of angle Kappa adjustment between Oculyzer and Topolyzer Vario topography guided ablation of laser in situ keratomileusis (LASIK) by EX500 excimer laser for myopia. Totally 145 cases (290 consecutive eyes )with myopia received LASIK with a target of emmetropia. The ablation for 86 cases (172 eyes) was guided manually based on Oculyzer topography (study group), while the ablation for 59 cases (118 eyes) was guided automatically by Topolyzer Vario topography (control group). Measurement of adjustment values included data respectively in horizontal and vertical direction of cornea. Horizontally, synclastic adjustment between manually actual values (dx manu ) and Oculyzer topography guided data (dx ocu ) accounts 35.5% in study group, with mean dx manu /dx ocu of 0.78±0.48; while in control group, synclastic adjustment between automatically actual values (dx auto ) and Oculyzer topography data (dx ocu ) accounts 54.2%, with mean dx auto /dx ocu of 0.79±0.66. Vertically, synclastic adjustment between dy manu and dy ocu accounts 55.2% in study group, with mean dy manu /dy ocu of 0.61±0.42; while in control group, synclastic adjustment between dy auto and dy ocu accounts 66.1%, with mean dy auto /dy ocu of 0.66±0.65. There was no statistically significant difference in ratio of actual values/Oculyzer topography guided data in horizontal and vertical direction between two groups ( P =0.951, 0.621). There is high consistency in angle Kappa adjustment guided manually by Oculyzer and guided automatically by Topolyzer Vario topography during corneal refractive surgery by WaveLight EX500 excimer laser.

Excimer laser recrystallization of nanocrystalline-Si films deposited by inductively coupled plasma chemical vapour deposition at 150 deg. C

International Nuclear Information System (INIS)

Park, Joong-Hyun; Han, Sang-Myeon; Park, Sang-Geun; Han, Min-Koo; Shin, Moon-Young

2006-01-01

Polycrystalline silicon thin film transistors (poly-Si TFTs) fabricated at low temperature (under 200 deg. C) have been widely investigated for flexible substrate applications such as a transparent plastic substrate. Unlike the conventional TFT process using glass substrate, the maximum process temperature should be kept less than 200 deg. C in order to avoid thermal damage on flexible substrates. We report the characteristics of nanocrystalline silicon (nc-Si) irradiated by an excimer laser. Nc-Si precursors were deposited on various buffer layers by inductively coupled plasma chemical vapour deposition (ICP-CVD) at 150 deg. C. We employed various buffer layers, such as silicon nitride (SiN X ) and silicon dioxide (SiO 2 ), in order to report recrystallization characteristics in connection with a buffer layer of a different thermal conductivity. The dehydrogenation and recrystallization was performed by step-by-step excimer laser annealing (ELA) (XeCl,λ=308 nm) in order to prevent the explosive release of hydrogen atoms. The grain size of the poly-Si film, which was recrystallized on the various buffer layers, was measured by scanning electron microscopy (SEM) at each laser energy density. The process margin of step-by-step ELA employing the SiN X buffer layer is wider than SiO 2 and the maximum grain size slightly increased

Microencapsulation of silicon cavities using a pulsed excimer laser

KAUST Repository

Sedky, Sherif M.

2012-06-07

This work presents a novel low thermal-budget technique for sealing micromachined cavities in silicon. Cavities are sealed without deposition, similar to the silicon surface-migration sealing process. In contrast to the 1100°C furnace anneal required for the migration process, the proposed technique uses short excimer laser pulses (24ns), focused onto an area of 23mm 2, to locally heat the top few microns of the substrate, while the bulk substrate remains near ambient temperature. The treatment can be applied to selected regions of the substrate, without the need for special surface treatments or a controlled environment. This work investigates the effect of varying the laser pulse energy from 400 mJ cm 2to 800 mJ cm 2, the pulse rate from 1Hz to 50Hz and the pulse count from 200 to 3000 pulses on sealing microfabricated cavities in silicon. An analytical model for the effect of holes on the surface temperature distribution is derived, which shows that much higher temperatures can be achieved by increasing the hole density. A mechanism for sealing the cavities is proposed, which indicates how complete sealing is feasible. © 2012 IOP Publishing Ltd.

Applications of high power microwaves

International Nuclear Information System (INIS)

Benford, J.; Swegle, J.

1993-01-01

The authors address a number of applications for HPM technology. There is a strong symbiotic relationship between a developing technology and its emerging applications. New technologies can generate new applications. Conversely, applications can demand development of new technological capability. High-power microwave generating systems come with size and weight penalties and problems associated with the x-radiation and collection of the electron beam. Acceptance of these difficulties requires the identification of a set of applications for which high-power operation is either demanded or results in significant improvements in peRFormance. The authors identify the following applications, and discuss their requirements and operational issues: (1) High-energy RF acceleration; (2) Atmospheric modification (both to produce artificial ionospheric mirrors for radio waves and to save the ozone layer); (3) Radar; (4) Electronic warfare; and (5) Laser pumping. In addition, they discuss several applications requiring high average power than border on HPM, power beaming and plasma heating

Study on excimer laser irradiation for controlled dehydrogenation and crystallization of boron doped hydrogenated amorphous/nanocrystalline silicon multilayers

International Nuclear Information System (INIS)

Gontad, F.; Conde, J.C.; Filonovich, S.; Cerqueira, M.F.; Alpuim, P.; Chiussi, S.

2013-01-01

We report on the excimer laser annealing (ELA) induced temperature gradients, allowing controlled crystallization and dehydrogenation of boron-doped a-Si:H/nc-Si:H multilayers. Depth of the dehydrogenation and crystallization process has been studied numerically and experimentally, showing that temperatures below the monohydride decomposition can be used and that significant changes of the doping profile can be avoided. Calculation of temperature profiles has been achieved through numerical modeling of the heat conduction differential equation. Increase in the amount of nano-crystals, but not in their size, has been demonstrated by Raman spectroscopy. Effective dehydrogenation and shape of the boron profile have been studied by time of flight secondary ion mass spectroscopy. The relatively low temperature threshold for dehydrogenation, below the monohydride decomposition temperature, has been attributed to both, the large hydrogen content of the original films and the partial crystallization during the ELA process. The results of this study show that UV-laser irradiation is an effective tool to improve crystallinity and dopant activation in p + -nc-Si:H films without damaging the substrate. - Highlights: • An efficient dehydrogenation is possible through excimer laser annealing. • 140 mJ/cm 2 is enough for dehydrogenation without significant changes in doping profile. • Fluences up to 300 mJ/cm 2 promote partial crystallization of the amorphous structures

Study on excimer laser irradiation for controlled dehydrogenation and crystallization of boron doped hydrogenated amorphous/nanocrystalline silicon multilayers

Energy Technology Data Exchange (ETDEWEB)

Gontad, F., E-mail: fran_gontad@yahoo.es [Applied Physics Department, University of Vigo, E.I. Industrial, Campus de As Lagoas, Marcosende, E-36310, Vigo (Spain); Conde, J.C. [Applied Physics Department, University of Vigo, E.I. Industrial, Campus de As Lagoas, Marcosende, E-36310, Vigo (Spain); Filonovich, S.; Cerqueira, M.F.; Alpuim, P. [Department of Physics, University of Minho, Campus de Azurém, 4800-058 Guimarães (Portugal); Chiussi, S. [Applied Physics Department, University of Vigo, E.I. Industrial, Campus de As Lagoas, Marcosende, E-36310, Vigo (Spain)

2013-06-01

We report on the excimer laser annealing (ELA) induced temperature gradients, allowing controlled crystallization and dehydrogenation of boron-doped a-Si:H/nc-Si:H multilayers. Depth of the dehydrogenation and crystallization process has been studied numerically and experimentally, showing that temperatures below the monohydride decomposition can be used and that significant changes of the doping profile can be avoided. Calculation of temperature profiles has been achieved through numerical modeling of the heat conduction differential equation. Increase in the amount of nano-crystals, but not in their size, has been demonstrated by Raman spectroscopy. Effective dehydrogenation and shape of the boron profile have been studied by time of flight secondary ion mass spectroscopy. The relatively low temperature threshold for dehydrogenation, below the monohydride decomposition temperature, has been attributed to both, the large hydrogen content of the original films and the partial crystallization during the ELA process. The results of this study show that UV-laser irradiation is an effective tool to improve crystallinity and dopant activation in p{sup +}-nc-Si:H films without damaging the substrate. - Highlights: • An efficient dehydrogenation is possible through excimer laser annealing. • 140 mJ/cm{sup 2} is enough for dehydrogenation without significant changes in doping profile. • Fluences up to 300 mJ/cm{sup 2} promote partial crystallization of the amorphous structures.

A comparative study of via drilling and scribing on PEN and PET substrates for flexible electronic applications using excimer and Nd:YAG laser sources

NARCIS (Netherlands)

Mandamparambil, R.; Fledderus, H.; Brand, J. van den; Saalmink, M.; Kusters, R.; Podprocky, T.; Steenberge, G. van; Baets, J. de; Dietzel, A.H.

2009-01-01

A study on via drilling and channel scribing on PEN and PET substrates for flexible electronic application is discussed in this paper. For the experiments, both KIF excimer laser (248 nm) and frequency tripled Nd:YAG (355 nm) laser are used. Different measurement techniques like optical microscopy,

Boron distribution in silicon after excimer laser annealing with multiple pulses

International Nuclear Information System (INIS)

Monakhov, E.V.; Svensson, B.G.; Linnarsson, M.K.; La Magna, A.; Italia, M.; Privitera, V.; Fortunato, G.; Cuscuna, M.; Mariucci, L.

2005-01-01

We have studied B re-distribution in Si after excimer laser annealing (ELA) with multiple laser pulses. B was implanted using both B and BF 2 ions with energies from 1 to 20 keV and doses of 1 x 10 14 and 1 x 10 15 cm -2 . ELA with the number of pulses from 1 to 100 was performed in vacuum with the sample kept at room temperature and 450 deg. C. Independently of the implantation parameters and the ELA conditions used, a peak in the B concentration is observed near the maximum melting depth after 10 pulses of ELA. A detailed study has revealed that B accumulates at the maximum melt depth gradually with the number of ELA pulses. An increase in the carrier concentration at the maximum melt depth is observed after ELA with 100 pulses. No structural defects have been detected by transmission electron microscopy in the region of the B accumulation

Preparation of PZT/YBCO/YAlO heterostructure thin films by KrF excimer laser ablation

International Nuclear Information System (INIS)

Ebihara, Kenji; Kurogi, Hiromitsu; Yamagata, Yukihiko; Ikegami, Tomoaki; Grishin, A.M.

1998-01-01

The perovskite oxide YBa 2 Cu 3 O 7-x (YBCO) and Pb(Zr x Ti 1-x )O 3 (PZT) thin films have been deposited for superconducting-ferroelectric devices. KrF excimer laser ablation technique was used at the deposition conditions of 200--600 mTorr O 2 , 2-3J/cm 2 and 5--10 Hz operation frequency. Heterostructures of PZT-YBCO-YAlO 3 :Nd show the zero resistivity critical temperature of 82 K and excellent ferroelectric properties of remnant polarization 32 microC/cm 2 , coercive force of 80 kV/cm and dielectric constant 800. Cycling fatigue characteristics and leakage current are also discussed

Optics assembly for high power laser tools

Science.gov (United States)

Fraze, Jason D.; Faircloth, Brian O.; Zediker, Mark S.

2016-06-07

There is provided a high power laser rotational optical assembly for use with, or in high power laser tools for performing high power laser operations. In particular, the optical assembly finds applications in performing high power laser operations on, and in, remote and difficult to access locations. The optical assembly has rotational seals and bearing configurations to avoid contamination of the laser beam path and optics.

HIGH AVERAGE POWER OPTICAL FEL AMPLIFIERS

International Nuclear Information System (INIS)

2005-01-01

Historically, the first demonstration of the optical FEL was in an amplifier configuration at Stanford University [l]. There were other notable instances of amplifying a seed laser, such as the LLNL PALADIN amplifier [2] and the BNL ATF High-Gain Harmonic Generation FEL [3]. However, for the most part FELs are operated as oscillators or self amplified spontaneous emission devices. Yet, in wavelength regimes where a conventional laser seed can be used, the FEL can be used as an amplifier. One promising application is for very high average power generation, for instance FEL's with average power of 100 kW or more. The high electron beam power, high brightness and high efficiency that can be achieved with photoinjectors and superconducting Energy Recovery Linacs (ERL) combine well with the high-gain FEL amplifier to produce unprecedented average power FELs. This combination has a number of advantages. In particular, we show that for a given FEL power, an FEL amplifier can introduce lower energy spread in the beam as compared to a traditional oscillator. This properly gives the ERL based FEL amplifier a great wall-plug to optical power efficiency advantage. The optics for an amplifier is simple and compact. In addition to the general features of the high average power FEL amplifier, we will look at a 100 kW class FEL amplifier is being designed to operate on the 0.5 ampere Energy Recovery Linac which is under construction at Brookhaven National Laboratory's Collider-Accelerator Department

Application of high power microwave vacuum electron devices

International Nuclear Information System (INIS)

Ding Yaogen; Liu Pukun; Zhang Zhaochuan; Wang Yong; Shen Bin

2011-01-01

High power microwave vacuum electron devices can work at high frequency, high peak and average power. They have been widely used in military and civil microwave electron systems, such as radar, communication,countermeasure, TV broadcast, particle accelerators, plasma heating devices of fusion, microwave sensing and microwave heating. In scientific research, high power microwave vacuum electron devices are used mainly on high energy particle accelerator and fusion research. The devices include high peak power klystron, CW and long pulse high power klystron, multi-beam klystron,and high power gyrotron. In national economy, high power microwave vacuum electron devices are used mainly on weather and navigation radar, medical and radiation accelerator, TV broadcast and communication system. The devices include high power pulse and CW klystron, extended interaction klystron, traveling wave tube (TWT), magnetron and induced output tube (IOT). The state of art, common technology problems and trends of high power microwave vacuum electron devices are introduced in this paper. (authors)

ArF excimer laser modulation of TNF-alpha and gelatinase B in NIH 3T3 cells

International Nuclear Information System (INIS)

Naudy-Vives, C.; Courant, D.; Perot, J.C.; Garcia, J.; Fretier, P.; Court, L.; Dormont, D.

1995-01-01

The effects on TNF-alpha and gelatinase B activity in mammalian cells induced by 193 nm argon fluoride excimer laser have been investigated. The data show that a secretion of 92 kDa type IV collagenase and TNF-alpha were increased in cell culture supernatants. Moreover, the 193 nm laser radiation produces a decrease of cell proliferation and an increase of cell activation 8 hours after irradiation. The total protein amount increases with the delivered dose. Same, but less effects were obtained after exposure to a conventional UV lamp at 254 nm. (author)

Analysis of excimer laser radiant exposure effect toward corneal ablation volume at LASIK procedure

Science.gov (United States)

Adiati, Rima Fitria; Rini Rizki, Artha Bona; Kusumawardhani, Apriani; Setijono, Heru; Rahmadiansah, Andi

2016-11-01

LASIK (Laser Asissted In Situ Interlamelar Keratomilieusis) is a technique for correcting refractive disorders of the eye such as myopia and astigmatism using an excimer laser. This procedure use photoablation technique to decompose corneal tissues. Although preferred due to its efficiency, permanency, and accuracy, the inappropriate amount radiant exposure often cause side effects like under-over correction, irregular astigmatism and problems on surrounding tissues. In this study, the radiant exposure effect toward corneal ablation volume has been modelled through several processes. Data collecting results is laser data specifications with 193 nm wavelength, beam diameter of 0.065 - 0.65 cm, and fluence of 160 mJ/cm2. For the medical data, the myopia-astigmatism value, cornea size, corneal ablation thickness, and flap data are taken. The first modelling step is determining the laser diameter between 0.065 - 0.65 cm with 0.45 cm increment. The energy, power, and intensity of laser determined from laser beam area. Number of pulse and total energy is calculated before the radiant exposure of laser is obtained. Next is to determine the parameters influence the ablation volume. Regression method used to create the equation, and then the spot size is substituted to the model. The validation used is statistic correlation method to both experimental data and theory. By the model created, it is expected that any potential complications can be prevented during LASIK procedures. The recommendations can give the users clearer picture to determine the appropriate amount of radiant exposure with the corneal ablation volume necessary.

14 CFR 101.25 - Operating limitations for Class 2-High Power Rockets and Class 3-Advanced High Power Rockets.

Science.gov (United States)

2010-01-01

... Power Rockets and Class 3-Advanced High Power Rockets. 101.25 Section 101.25 Aeronautics and Space... OPERATING RULES MOORED BALLOONS, KITES, AMATEUR ROCKETS AND UNMANNED FREE BALLOONS Amateur Rockets § 101.25 Operating limitations for Class 2-High Power Rockets and Class 3-Advanced High Power Rockets. When operating...

High-frequency high-voltage high-power DC-to-DC converters

Science.gov (United States)

Wilson, T. G.; Owen, H. A.; Wilson, P. M.

1982-09-01

A simple analysis of the current and voltage waveshapes associated with the power transistor and the power diode in an example current-or-voltage step-up (buck-boost) converter is presented. The purpose of the analysis is to provide an overview of the problems and design trade-offs which must be addressed as high-power high-voltage converters are operated at switching frequencies in the range of 100 kHz and beyond. Although the analysis focuses on the current-or-voltage step-up converter as the vehicle for discussion, the basic principles presented are applicable to other converter topologies as well.

Unscheduled DNA synthesis in human skin after in vitro ultraviolet-excimer laser ablation

Energy Technology Data Exchange (ETDEWEB)

Green, H.A.; Margolis, R.; Boll, J.; Kochevar, I.E.; Parrish, J.A.; Oseroff, A.R.

1987-08-01

DNA damage repaired by the excision repair system and measured as unscheduled DNA synthesis (UDS) was assessed in freshly excised human skin after 193 and 248 nm ultraviolet (UV)-excimer laser ablative incisions. Laser irradiation at 248 nm induced DNA damage throughout a zone of cells surrounding the ablated and heat-damaged area. In contrast, with 193 nm irradiation UDS was not detected in cells adjacent to the ablated area, even though DNA strongly absorbs this wavelength. Our results suggest that the lack of UDS after 193 nm irradiation is due to: ''shielding'' of DNA by the cellular interstitium, membrane, and cytoplasm, DNA damage that is not repaired by excision repair, or thermal effects that either temporarily or permanently inhibit the excision repair processes.

Excimer laser development for fusion

International Nuclear Information System (INIS)

Giovanielli, D.

1985-01-01

The future utility of inertial confinement fusion requires a new driver. Successful experiments coupling laser energy to targets, and our understanding of fuel capsule behavior strongly suggest that a laboratory thermonuclear source is attainable and power production may be considered if a suitable driver with high efficiency, high repetition rate, and most importantly, low capital cost, can be identified. No adequate driver exists today; however, the krypton fluoride laser holds great promise. By the end of this decade, driver development can be brought to the point that a technically justifiable choice can be made for the future direction of ICF

High-power, high-efficiency FELs

International Nuclear Information System (INIS)

Sessler, A.M.

1989-04-01

High power, high efficiency FELs require tapering, as the particles loose energy, so as to maintain resonance between the electromagnetic wave and the particles. They also require focusing of the particles (usually done with curved pole faces) and focusing of the electromagnetic wave (i.e. optical guiding). In addition, one must avoid transverse beam instabilities (primarily resistive wall) and longitudinal instabilities (i.e sidebands). 18 refs., 7 figs., 3 tabs

Water Vapour Propulsion Powered by a High-Power Laser-Diode

Science.gov (United States)

Minami, Y.; Uchida, S.

Most of the laser propulsion schemes now being proposed and developed assume neither power supplies nor on-board laser devices and therefore are bound to remote laser stations like a kite via a laser beam “string”. This is a fatal disadvantage for a space vehicle that flies freely though it is often said that no need of installing an energy source is an advantage of a laser propulsion scheme. The possibility of an independent laser propulsion space vehicle that carries a laser source and a power supply on board is discussed. This is mainly due to the latest development of high power laser diode (LD) technology. Both high specific impulse-low thrust mode and high thrust-low specific impulse mode can be selected by controlling the laser output by using vapour or water as a propellant. This mode change can be performed by switching between a high power continuous wave (cw), LD engine for high thrust with a low specific impulse mode and high power LD pumping Q-switched Nd:YAG laser engine for low thrust with the high specific impulse mode. This paper describes an Orbital Transfer Vehicle equipped with the above-mentioned laser engine system and fuel cell that flies to the Moon from a space platform or space hotel in Earth orbit, with cargo shipment from lunar orbit to the surface of the Moon, including the possibility of a sightseeing trip.

Properties of the ablation process for excimer laser ablation of Y1Ba2Cu3O7

International Nuclear Information System (INIS)

Neifeld, R.A.; Potenziani, E.; Sinclair, W.R.; Hill III, W.T.; Turner, B.; Pinkas, A.

1991-01-01

The process of excimer laser ablation has been studied while varying the laser fluence from 0.237 to 19.1 J/cm 2 . Ion time-of-flight, total charge, target etch depth per pulse, and etch volume per pulse have been measured. Results indicate a maximum ablation volume and minimum ionization fraction occur near 5 J/cm 2 . Several of the parameters measured vary rapidly in the 1--5 J/cm 2 range. Variation in these parameters strongly influences the properties of films grown by this technique

High speed micromachining with high power UV laser

Science.gov (United States)

Patel, Rajesh S.; Bovatsek, James M.

2013-03-01

Increasing demand for creating fine features with high accuracy in manufacturing of electronic mobile devices has fueled growth for lasers in manufacturing. High power, high repetition rate ultraviolet (UV) lasers provide an opportunity to implement a cost effective high quality, high throughput micromachining process in a 24/7 manufacturing environment. The energy available per pulse and the pulse repetition frequency (PRF) of diode pumped solid state (DPSS) nanosecond UV lasers have increased steadily over the years. Efficient use of the available energy from a laser is important to generate accurate fine features at a high speed with high quality. To achieve maximum material removal and minimal thermal damage for any laser micromachining application, use of the optimal process parameters including energy density or fluence (J/cm2), pulse width, and repetition rate is important. In this study we present a new high power, high PRF QuasarR 355-40 laser from Spectra-Physics with TimeShiftTM technology for unique software adjustable pulse width, pulse splitting, and pulse shaping capabilities. The benefits of these features for micromachining include improved throughput and quality. Specific example and results of silicon scribing are described to demonstrate the processing benefits of the Quasar's available power, PRF, and TimeShift technology.

Power affects performance when the pressure is on: evidence for low-power threat and high-power lift.

Science.gov (United States)

Kang, Sonia K; Galinsky, Adam D; Kray, Laura J; Shirako, Aiwa

2015-05-01

The current research examines how power affects performance in pressure-filled contexts. We present low-power-threat and high-power-lift effects, whereby performance in high-stakes situations suffers or is enhanced depending on one's power; that is, the power inherent to a situational role can produce effects similar to stereotype threat and lift. Three negotiations experiments demonstrate that role-based power affects outcomes but only when the negotiation is diagnostic of ability and, therefore, pressure-filled. We link these outcomes conceptually to threat and lift effects by showing that (a) role power affects performance more strongly when the negotiation is diagnostic of ability and (b) underperformance disappears when the low-power negotiator has an opportunity to self-affirm. These results suggest that stereotype threat and lift effects may represent a more general phenomenon: When the stakes are raised high, relative power can act as either a toxic brew (stereotype/low-power threat) or a beneficial elixir (stereotype/high-power lift) for performance. © 2015 by the Society for Personality and Social Psychology, Inc.

Application of laser resonance scattering to the study of high-temperature plasma-wall interaction

International Nuclear Information System (INIS)

Maeda, Mitsuo; Muraoka, Katsunori; Hamamoto, Makoto; Akazaki, Masanori; Miyazoe, Yasushi

1981-01-01

Studies on laser resonance scattering and its application to the study of high-temperature plasma-wall interaction are reviewed. The application of dye laser beam to resonant scattering method has been developed. This method is able to detect low density atoms. The fluorescent photon counts can be estimated for a two-level system and a three-level system. The S/N ratio, Which is in close connection with the detection limit, has been estimated. The doppler effect due to the thermal motion of atoms is taken into consideration. The calibration of the absolute number of atoms is necessary. Tunable coherent light is used as the light source for resonance scattering method. This is able to excite atoms strongly and to increase the detection efficiency. As dye lasers, a N 2 laser, a YAG laser, and a KrF excimer laser have been studied. In VUV region, rare gas or rare gas halide lasers can be used. The strong output power can be expected when the resonance lines of atoms meet the synchronizing region of the excimer laser. The resonance scattering method is applied to the detection of impurity metal atoms in plasma. The studies of laser systems for the detection of hydrogen atoms are also in progress. (Kato, T.)

Advanced High Voltage Power Device Concepts

CERN Document Server

Baliga, B Jayant

2012-01-01

Advanced High Voltage Power Device Concepts describes devices utilized in power transmission and distribution equipment, and for very high power motor control in electric trains and steel-mills. Since these devices must be capable of supporting more than 5000-volts in the blocking mode, this books covers operation of devices rated at 5,000-V, 10,000-V and 20,000-V. Advanced concepts (the MCT, the BRT, and the EST) that enable MOS-gated control of power thyristor structures are described and analyzed in detail. In addition, detailed analyses of the silicon IGBT, as well as the silicon carbide MOSFET and IGBT, are provided for comparison purposes. Throughout the book, analytical models are generated to give a better understanding of the physics of operation for all the structures. This book provides readers with: The first comprehensive treatment of high voltage (over 5000-volts) power devices suitable for the power distribution, traction, and motor-control markets;  Analytical formulations for all the device ...

High-power density miniscale power generation and energy harvesting systems

International Nuclear Information System (INIS)

Lyshevski, Sergey Edward

2011-01-01

This paper reports design, analysis, evaluations and characterization of miniscale self-sustained power generation systems. Our ultimate objective is to guarantee highly-efficient mechanical-to-electrical energy conversion, ensure premier wind- or hydro-energy harvesting capabilities, enable electric machinery and power electronics solutions, stabilize output voltage, etc. By performing the advanced scalable power generation system design, we enable miniscale energy sources and energy harvesting technologies. The proposed systems integrate: (1) turbine which rotates a radial- or axial-topology permanent-magnet synchronous generator at variable angular velocity depending on flow rate, speed and load, and, (2) power electronic module with controllable rectifier, soft-switching converter and energy storage stages. These scalable energy systems can be utilized as miniscale auxiliary and self-sustained power units in various applications, such as, aerospace, automotive, biotechnology, biomedical, and marine. The proposed systems uniquely suit various submersible and harsh environment applications. Due to operation in dynamic rapidly-changing envelopes (variable speed, load changes, etc.), sound solutions are researched, proposed and verified. We focus on enabling system organizations utilizing advanced developments for various components, such as generators, converters, and energy storage. Basic, applied and experimental findings are reported. The prototypes of integrated power generation systems were tested, characterized and evaluated. It is documented that high-power density, high efficiency, robustness and other enabling capabilities are achieved. The results and solutions are scalable from micro (∼100 μW) to medium (∼100 kW) and heavy-duty (sub-megawatt) auxiliary and power systems.

Development of a Silicon Based Electron Beam Transmission Window for Use in a KrF Excimer Laser System

International Nuclear Information System (INIS)

Gentile, C.A.; Fan, H.M.; Hartfield, J.W.; Hawryluk, R.J.; Hegeler, F.; Heitzenroeder, P.J.; Jun, C.H.; Ku, L.P.; LaMarche, P.H.; Myers, M.C.; Parker, J.J.; Parsells, R.F.; Payen, M.; Raftopoulos, S.; Sethian, J.D.

2002-01-01

The Princeton Plasma Physics Laboratory (PPPL), in collaboration with the Naval Research Laboratory (NRL), is currently investigating various novel materials (single crystal silicon, , and ) for use as electron-beam transmission windows in a KrF excimer laser system. The primary function of the window is to isolate the active medium (excimer gas) from the excitation mechanism (field-emission diodes). Chosen window geometry must accommodate electron energy transfer greater than 80% (750 keV), while maintaining structural integrity during mechanical load (1.3 to 2.0 atm base pressure differential, approximate 0.5 atm cyclic pressure amplitude, 5 Hz repetition rate) and thermal load across the entire hibachi area (approximate 0.9 W · cm superscript ''-2''). In addition, the window must be chemically resistant to attack by fluorine free-radicals (hydrofluoric acid, secondary). In accordance with these structural, functional, and operational parameters, a 22.4 mm square silicon prototype window, coated with 500 nm thin-film silicon nitride (Si 3 N 4 ), has been fabricated. The window consists of 81 square panes with a thickness of 0.019 mm ± 0.001 mm. Stiffened (orthogonal) sections are 0.065 mm in width and 0.500 mm thick (approximate). Appended drawing (Figure 1) depicts the window configuration. Assessment of silicon (and silicon nitride) material properties and CAD modeling and analysis of the window design suggest that silicon may be a viable solution to inherent parameters and constraints

Power MOSFET Linearizer of a High-Voltage Power Amplifier for High-Frequency Pulse-Echo Instrumentation.

Science.gov (United States)

Choi, Hojong; Woo, Park Chul; Yeom, Jung-Yeol; Yoon, Changhan

2017-04-04

A power MOSFET linearizer is proposed for a high-voltage power amplifier (HVPA) used in high-frequency pulse-echo instrumentation. The power MOSFET linearizer is composed of a DC bias-controlled series power MOSFET shunt with parallel inductors and capacitors. The proposed scheme is designed to improve the gain deviation characteristics of the HVPA at higher input powers. By controlling the MOSFET bias voltage in the linearizer, the gain reduction into the HVPA was compensated, thereby reducing the echo harmonic distortion components generated by the ultrasonic transducers. In order to verify the performance improvement of the HVPA implementing the power MOSFET linearizer, we measured and found that the gain deviation of the power MOSFET linearizer integrated with HVPA under 10 V DC bias voltage was reduced (-1.8 and -0.96 dB, respectively) compared to that of the HVPA without the power MOSFET linearizer (-2.95 and -3.0 dB, respectively) when 70 and 80 MHz, three-cycle, and 26 dB m input pulse waveforms are applied, respectively. The input 1-dB compression point (an index of linearity) of the HVPA with power MOSFET linearizer (24.17 and 26.19 dB m at 70 and 80 MHz, respectively) at 10 V DC bias voltage was increased compared to that of HVPA without the power MOSFET linearizer (22.03 and 22.13 dB m at 70 and 80 MHz, respectively). To further verify the reduction of the echo harmonic distortion components generated by the ultrasonic transducers, the pulse-echo responses in the pulse-echo instrumentation were compared when using HVPA with and without the power MOSFET linearizer. When three-cycle 26 dB m input power was applied, the second, third, fourth, and fifth harmonic distortion components of a 75 MHz transducer driven by the HVPA with power MOSFET linearizer (-48.34, -44.21, -48.34, and -46.56 dB, respectively) were lower than that of the HVPA without the power MOSFET linearizer (-45.61, -41.57, -45.01, and -45.51 dB, respectively). When five-cycle 20 dB m input

High Power Orbit Transfer Vehicle

National Research Council Canada - National Science Library

Gulczinski, Frank

2003-01-01

... from Virginia Tech University and Aerophysics, Inc. to examine propulsion requirements for a high-power orbit transfer vehicle using thin-film voltaic solar array technologies under development by the Space Vehicles Directorate (dubbed PowerSail...

High impact data visualization with Power View, Power Map, and Power BI

CERN Document Server

Aspin, Adam

2014-01-01

High Impact Data Visualization with Power View, Power Map, and Power BI helps you take business intelligence delivery to a new level that is interactive, engaging, even fun, all while driving commercial success through sound decision-making. Learn to harness the power of Microsoft's flagship, self-service business intelligence suite to deliver compelling and interactive insight with remarkable ease. Learn the essential techniques needed to enhance the look and feel of reports and dashboards so that you can seize your audience's attention and provide them with clear and accurate information. Al

Eighth CW and High Average Power RF Workshop

CERN Document Server

2014-01-01

We are pleased to announce the next Continuous Wave and High Average RF Power Workshop, CWRF2014, to take place at Hotel NH Trieste, Trieste, Italy from 13 to 16 May, 2014. This is the eighth in the CWRF workshop series and will be hosted by Elettra - Sincrotrone Trieste S.C.p.A. (www.elettra.eu). CWRF2014 will provide an opportunity for designers and users of CW and high average power RF systems to meet and interact in a convivial environment to share experiences and ideas on applications which utilize high-power klystrons, gridded tubes, combined solid-state architectures, high-voltage power supplies, high-voltage modulators, high-power combiners, circulators, cavities, power couplers and tuners. New ideas for high-power RF system upgrades and novel ways of RF power generation and distribution will also be discussed. CWRF2014 sessions will start on Tuesday morning and will conclude on Friday lunchtime. A visit to Elettra and FERMI will be organized during the workshop. ORGANIZING COMMITTEE (OC): Al...

Modeling of excimer laser radiation induced defect generation in fluoride phosphate glasses

International Nuclear Information System (INIS)

Natura, U.; Ehrt, D.

2001-01-01

Fluoride phosphate (FP) glasses with low phosphate content are high-transparent in the deep ultraviolet (UV) range and attractive candidates for UV-optics. Their optical properties are complementary to fluoride crystals. The anomalous partial dispersion makes them desirable for optical lens designs to reduce the secondary spectrum. Their UV transmission is limited by trace impurities introduced by raw materials and decreases when exposed to UV-radiation (lamps, lasers). The experiments of the paper published previously in this journal were used in order to separate radiation induced absorption bands in the fluoride phosphate glass FP10. In this paper the generation mechanism of the phosphorus-oxygen related hole center POHC 2 is investigated in detail in glasses of various compositions (various phosphate and impurity contents) in order to predict the transmission loss in case of long-time irradiation. Experiments were carried out using ArF- and KrF-excimer lasers (ns-pulses). POHC 2 generation strongly depends on the phosphate content and on the content of Pb 2+ . A model was developed on these terms. Rate equations are formulated, incorporating the influence of the Pb 2+ -content on the defect generation, a two-step creation term including an energy transfer process and a one-photon bleaching term. This results in a set of coupled nonlinear differential equations. Absorption coefficients and lifetimes of the excited states were calculated as well. Experimental results compared well with the numerical analysis of the theoretical rate equations

excimer laser

Indian Academy of Sciences (India)

2014-01-07

Jan 7, 2014 ... is necessary to deposit one order higher input electric power into gas medium than ... cross-sectional view of the laser system is shown in figure 2A. The system mainly consists ... Considering the simplicity and reliability of the.

Series-Tuned High Efficiency RF-Power Amplifiers

DEFF Research Database (Denmark)

Vidkjær, Jens

2008-01-01

An approach to high efficiency RF-power amplifier design is presented. It addresses simultaneously efficiency optimization and peak voltage limitations when transistors are pushed towards their power limits.......An approach to high efficiency RF-power amplifier design is presented. It addresses simultaneously efficiency optimization and peak voltage limitations when transistors are pushed towards their power limits....

High-power density miniscale power generation and energy harvesting systems

Energy Technology Data Exchange (ETDEWEB)

Lyshevski, Sergey Edward [Department of Electrical and Microelectronics Engineering, Rochester Institute of Technology, Rochester, NY 14623-5603 (United States)

2011-01-15

This paper reports design, analysis, evaluations and characterization of miniscale self-sustained power generation systems. Our ultimate objective is to guarantee highly-efficient mechanical-to-electrical energy conversion, ensure premier wind- or hydro-energy harvesting capabilities, enable electric machinery and power electronics solutions, stabilize output voltage, etc. By performing the advanced scalable power generation system design, we enable miniscale energy sources and energy harvesting technologies. The proposed systems integrate: (1) turbine which rotates a radial- or axial-topology permanent-magnet synchronous generator at variable angular velocity depending on flow rate, speed and load, and, (2) power electronic module with controllable rectifier, soft-switching converter and energy storage stages. These scalable energy systems can be utilized as miniscale auxiliary and self-sustained power units in various applications, such as, aerospace, automotive, biotechnology, biomedical, and marine. The proposed systems uniquely suit various submersible and harsh environment applications. Due to operation in dynamic rapidly-changing envelopes (variable speed, load changes, etc.), sound solutions are researched, proposed and verified. We focus on enabling system organizations utilizing advanced developments for various components, such as generators, converters, and energy storage. Basic, applied and experimental findings are reported. The prototypes of integrated power generation systems were tested, characterized and evaluated. It is documented that high-power density, high efficiency, robustness and other enabling capabilities are achieved. The results and solutions are scalable from micro ({proportional_to}100 {mu}W) to medium ({proportional_to}100 kW) and heavy-duty (sub-megawatt) auxiliary and power systems. (author)

Influence of laser fluence in ArF-excimer laser assisted crystallisation of a-SiGe:H films

International Nuclear Information System (INIS)

Chiussi, S.; Lopez, E.; Serra, J.; Gonzalez, P.; Serra, C.; Leon, B.; Fabbri, F.; Fornarini, L.; Martelli, S.

2003-01-01

Polycrystalline silicon germanium (poly-SiGe) coatings are drawing increasing attention as active layers in solar cells, bolometers and various microelectronic devices. As a consequence, alternative low-cost production techniques, capable to produce such alloys with uniform and controlled grain size, become more and more attractive. Excimer laser assisted crystallisation, already assessed in thin film transistor production, has proved to be a valuable 'low-thermal budget' technique for the crystallisation of amorphous silicon. Main advantages are the high process quality and reproducibility as well as the possibility of tailoring the grain size in both, small selected regions and large areas. The feasibility of this technique for producing poly-SiGe films has been studied irradiating hydrogenated amorphous SiGe films with spatially uniform ArF-laser pulses of different fluences. Surface morphology, structure and chemical composition have been extensively characterised, demonstrating the need of using a 'step-by-step' process and a careful adjustment of both, total number of shots and laser fluence at each 'step' in order to diminish segregation effects and severe damages of the film surface and of segregation effects

Charge carrier mobility and electronic properties of Al(Op3: impact of excimer formation

Directory of Open Access Journals (Sweden)

Andrea Magri

2015-05-01

Full Text Available We have studied the electronic properties and the charge carrier mobility of the organic semiconductor tris(1-oxo-1H-phenalen-9-olatealuminium(III (Al(Op3 both experimentally and theoretically. We experimentally estimated the HOMO and LUMO energy levels to be −5.93 and −3.26 eV, respectively, which were close to the corresponding calculated values. Al(Op3 was successfully evaporated onto quartz substrates and was clearly identified in the absorption spectra of both the solution and the thin film. A structured steady state fluorescence emission was detected in solution, whereas a broad, red-shifted emission was observed in the thin film. This indicates the formation of excimers in the solid state, which is crucial for the transport properties. The incorporation of Al(Op3 into organic thin film transistors (TFTs was performed in order to measure the charge carrier mobility. The experimental setup detected no electron mobility, while a hole mobility between 0.6 × 10−6 and 2.1 × 10−6 cm2·V−1·s−1 was measured. Theoretical simulations, on the other hand, predicted an electron mobility of 9.5 × 10−6 cm2·V−1·s−1 and a hole mobility of 1.4 × 10−4 cm2·V−1·s−1. The theoretical simulation for the hole mobility predicted an approximately one order of magnitude higher hole mobility than was observed in the experiment, which is considered to be in good agreement. The result for the electron mobility was, on the other hand, unexpected, as both the calculated electron mobility and chemical common sense (based on the capability of extended aromatic structures to efficiently accept and delocalize additional electrons suggest more robust electron charge transport properties. This discrepancy is explained by the excimer formation, whose inclusion in the multiscale simulation workflow is expected to bring the theoretical simulation and experiment into agreement.

Hydrophilicity and morphological investigation of polycarbonate irradiated by ArF excimer laser

Energy Technology Data Exchange (ETDEWEB)

Jaleh, B. [Bu-Ali-Sina University, Physics Department, Postal Code 65174, Hamedan (Iran, Islamic Republic of)], E-mail: jaleh@basu.ac.ir; Parvin, P. [Amir Kabir University of Technology, Physics Department, P.O. Box: 15875-4413, Tehran (Iran, Islamic Republic of); Laser Research Center, AEOI, P.O. Box: 11365-8486, Tehran (Iran, Islamic Republic of); Sheikh, N. [Nuclear Science and Technology Research Institute, Radiation Applications Research School, Tehran (Iran, Islamic Republic of); Zamanipour, Z. [Laser Research Center, AEOI, P.O. Box: 11365-8486, Tehran (Iran, Islamic Republic of); Sajad, B. [Azzahra University, Physics Department, Tehran (Iran, Islamic Republic of)

2007-12-15

Lasers are used to modify polymeric materials. In this work, a number of polycarbonate (PC) pieces were exposed by ArF excimer laser, 193 nm, at various UV doses from 10 to 100 J/cm{sup 2} with 50-500 mJ/pulse at 10 Hz pulse repetition rate. Morphology of PC has been investigated by scanning electron microscope (SEM) at three regimes pre-ablation, slow and fast ablation. SEM identifies that the conical defects are created on the polymer surface to grow opposite to the direction of laser irradiation. It increases the superficial absorptivity of the material dependent on the ArF laser induced conical microstructure geometry. The contact angle measurement was performed here, in order to determine the hydrophilicity of the irradiated polymer at various coherent doses. It is shown that the contact angle of PC samples which are exposed to the ArF laser significantly alters with UV dose below 7 J/cm{sup 2}.

high power facto high power factor high power factor hybrid rectifier

African Journals Online (AJOL)

eobe

increase in the number of electrical loads that some kind of ... components in the AC power system. Thus, suppl ... al output power; assuring reliability in ... distribution systems. This can be ...... Thesis- Califonia Institute of Technology, Capitulo.

Boron-enhanced diffusion in excimer laser annealed Si

International Nuclear Information System (INIS)

Monakhov, E.V.; Svensson, B.G.; Linnarsson, M.K.; La Magna, A.; Privitera, V.; Fortunato, G.; Mariucci, L.

2004-01-01

The effect of excimer laser annealing (ELA) and rapid thermal annealing (RTA) on B redistribution in B-implanted Si has been studied by secondary ion mass spectrometry (SIMS) and spreading resistance probe (SRP). B has been implanted with an energy of 1 keV and a dose of 10 16 cm -2 forming a distribution with a width of 20-30 nm and a peak concentration of ∼5 x 10 21 cm -3 . It has been found that ELA with 10 pulses of the energy density of 850 mJ/cm 2 results in a uniform B distribution over the ELA-molten region with an abrupt profile edge. SRP measurements demonstrate good activation of the implanted B after ELA, with the concentration of the activated fraction (∼10 21 cm -3 ) exceeding the solid solubility level. RTA (30 s at 1100 deg. C) of the as-implanted and ELA-treated samples leads to a diffusion of B with diffusivities exceeding the equilibrium one and the enhancement is similar for both of the samples. It is also found that RTA decreases the activated B in the ELA-treated sample to the solid solubility limit (2 x 10 20 cm -3 ). The similarity of the B diffusivity for the as-implanted and ELA-treated samples suggests that the enhancement of the B diffusivity is due to the so-called boron-enhanced diffusion (BED). Possible mechanisms of BED are discussed

Electronic DC transformer with high power density

NARCIS (Netherlands)

Pavlovský, M.

2006-01-01

This thesis is concerned with the possibilities of increasing the power density of high-power dc-dc converters with galvanic isolation. Three cornerstones for reaching high power densities are identified as: size reduction of passive components, reduction of losses particularly in active components

Sexual aggression when power is new: Effects of acute high power on chronically low-power individuals.

Science.gov (United States)

Williams, Melissa J; Gruenfeld, Deborah H; Guillory, Lucia E

2017-02-01

Previous theorists have characterized sexually aggressive behavior as an expression of power, yet evidence that power causes sexual aggression is mixed. We hypothesize that power can indeed create opportunities for sexual aggression-but that it is those who chronically experience low power who will choose to exploit such opportunities. Here, low-power men placed in a high-power role showed the most hostility in response to a denied opportunity with an attractive woman (Studies 1 and 2). Chronically low-power men and women given acute power were the most likely to say they would inappropriately pursue an unrequited workplace attraction (Studies 3 and 4). Finally, having power over an attractive woman increased harassment behavior among men with chronic low, but not high, power (Study 5). People who see themselves as chronically denied power appear to have a stronger desire to feel powerful and are more likely to use sexual aggression toward that end. (PsycINFO Database Record (c) 2017 APA, all rights reserved).

Switching transients in high-frequency high-power converters using power MOSFET's

Science.gov (United States)

Sloane, T. H.; Owen, H. A., Jr.; Wilson, T. G.

1979-01-01

The use of MOSFETs in a high-frequency high-power dc-to-dc converter is investigated. Consideration is given to the phenomena associated with the paralleling of MOSFETs and to the effect of stray circuit inductances on the converter circuit performance. Analytical relationships between various time constants during the turning-on and turning-off intervals are derived which provide estimates of plateau and peak levels during these intervals.

High Power Electron Accelerator Prototype

CERN Document Server

Tkachenko, Vadim; Cheskidov, Vladimir; Korobeynikov, G I; Kuznetsov, Gennady I; Lukin, A N; Makarov, Ivan; Ostreiko, Gennady; Panfilov, Alexander; Sidorov, Alexey; Tarnetsky, Vladimir V; Tiunov, Michael A

2005-01-01

In recent time the new powerful industrial electron accelerators appear on market. It caused the increased interest to radiation technologies using high energy X-rays due to their high penetration ability. However, because of low efficiency of X-ray conversion for electrons with energy below 5 MeV, the intensity of X-rays required for some industrial applications can be achieved only when the beam power exceeds 300 kW. The report describes a project of industrial electron accelerator ILU-12 for electron energy up to 5 MeV and beam power up to 300 kW specially designed for use in industrial applications. On the first stage of work we plan to use the existing generator designed for ILU-8 accelerator. It is realized on the GI-50A triode and provides the pulse power up to 1.5-2 MW and up to 20-30 kW of average power. In the report the basic concepts and a condition of the project for today are reflected.

Resonant High Power Combiners

CERN Document Server

Langlois, Michel; Peillex-Delphe, Guy

2005-01-01

Particle accelerators need radio frequency sources. Above 300 MHz, the amplifiers mostly used high power klystrons developed for this sole purpose. As for military equipment, users are drawn to buy "off the shelf" components rather than dedicated devices. IOTs have replaced most klystrons in TV transmitters and find their way in particle accelerators. They are less bulky, easier to replace, more efficient at reduced power. They are also far less powerful. What is the benefit of very compact sources if huge 3 dB couplers are needed to combine the power? To alleviate this drawback, we investigated a resonant combiner, operating in TM010 mode, able to combine 3 to 5 IOTs. Our IOTs being able to deliver 80 kW C.W. apiece, combined power would reach 400 kW minus the minor insertion loss. Values for matching and insertion loss are given. The behavior of the system in case of IOT failure is analyzed.

High Average Power, High Energy Short Pulse Fiber Laser System

Energy Technology Data Exchange (ETDEWEB)

Messerly, M J

2007-11-13

Recently continuous wave fiber laser systems with output powers in excess of 500W with good beam quality have been demonstrated [1]. High energy, ultrafast, chirped pulsed fiber laser systems have achieved record output energies of 1mJ [2]. However, these high-energy systems have not been scaled beyond a few watts of average output power. Fiber laser systems are attractive for many applications because they offer the promise of high efficiency, compact, robust systems that are turn key. Applications such as cutting, drilling and materials processing, front end systems for high energy pulsed lasers (such as petawatts) and laser based sources of high spatial coherence, high flux x-rays all require high energy short pulses and two of the three of these applications also require high average power. The challenge in creating a high energy chirped pulse fiber laser system is to find a way to scale the output energy while avoiding nonlinear effects and maintaining good beam quality in the amplifier fiber. To this end, our 3-year LDRD program sought to demonstrate a high energy, high average power fiber laser system. This work included exploring designs of large mode area optical fiber amplifiers for high energy systems as well as understanding the issues associated chirped pulse amplification in optical fiber amplifier systems.

Power Constrained High-Level Synthesis of Battery Powered Digital Systems

DEFF Research Database (Denmark)

Nielsen, Sune Fallgaard; Madsen, Jan

2003-01-01

We present a high-level synthesis algorithm solving the combined scheduling, allocation and binding problem minimizing area under both latency and maximum power per clock-cycle constraints. Our approach eliminates the large power spikes, resulting in an increased battery lifetime, a property...... of utmost importance for battery powered embedded systems. Our approach extends the partial-clique partitioning algorithm by introducing power awareness through a heuristic algorithm which bounds the design space to those of power feasible schedules. We have applied our algorithm on a set of dataflow graphs...

High stability, high current DC-power supplies

International Nuclear Information System (INIS)

Hosono, K.; Hatanaka, K.; Itahashi, T.

1995-01-01

Improvements of the power supplies and the control system of the AVF cyclotron which is used as an injector to the ring cyclotron and of the transport system to the ring cyclotron were done in order to get more high quality and more stable beam. The power supply of the main coil of the AVF cyclotron was exchanged to new one. The old DCCTs (zero-flux current transformers) used for the power supplies of the trim coils of the AVF cyclotron were changed to new DCCTs to get more stability. The potentiometers used for the reference voltages in the other power supplies of the AVF cyclotron and the transport system were changed to the temperature controlled DAC method for numerical-value settings. This paper presents the results of the improvements. (author)

Outcomes of excimer laser enhancements in pseudophakic patients with multifocal intraocular lens

Directory of Open Access Journals (Sweden)

Schallhorn SC

2016-04-01

Full Text Available Steven C Schallhorn,1–3 Jan A Venter,2 David Teenan,2 Julie M Schallhorn,3 Keith A Hettinger,2 Stephen J Hannan,2 Martina Pelouskova2 1Department of Ophthalmology, University of California, San Francisco, CA, USA; 2Optical Express, Glasgow, UK; 3Department of Ophthalmology, University of Southern California, Los Angeles, CA, USA Purpose: The aim of this study was to assess visual and refractive outcomes of laser vision correction (LVC to correct residual refraction after multifocal intraocular lens (IOL implantation. Patients and methods: In this retrospective study, 782 eyes that underwent LVC to correct unintended ametropia after multifocal IOL implantation were evaluated. Of all multifocal lenses implanted during primary procedure, 98.7% were refractive and 1.3% had a diffractive design. All eyes were treated with VISX STAR S4 IR excimer laser using a convectional ablation profile. Refractive outcomes, visual acuities, patient satisfaction, and quality of life were evaluated at the last available visit. Results: The mean time between enhancement and last visit was 6.3±4.4 months. Manifest spherical equivalent changed from -0.02±0.83 D (-3.38 D to +2.25 D pre-enhancement to 0.00±0.34 D (-1.38 D to +1.25 D post-enhancement. At the last follow-up, the percentage of eyes within 0.50 D and 1.00 D of emmetropia was 90.4% and 99.5%, respectively. Of all eyes, 74.9% achieved monocular uncorrected distance visual acuity 20/20 or better. The mean corrected distance visual acuity remained the same before (-0.04±0.06 logMAR [logarithm of the minimum angle of resolution] and after LVC procedure (-0.04±0.07 logMAR; P=0.70. There was a slight improvement in visual phenomena (starburst, halo, glare, ghosting/double vision following the enhancement. No sight-threatening complications related to LVC occurred in this study. Conclusion: LVC in pseudophakic patients with multifocal IOL was safe, effective, and predictable in a large cohort of

Automated System Tests High-Power MOSFET's

Science.gov (United States)

Huston, Steven W.; Wendt, Isabel O.

1994-01-01

Computer-controlled system tests metal-oxide/semiconductor field-effect transistors (MOSFET's) at high voltages and currents. Measures seven parameters characterizing performance of MOSFET, with view toward obtaining early indication MOSFET defective. Use of test system prior to installation of power MOSFET in high-power circuit saves time and money.

Application of parallel connected power-MOSFET elements to high current d.c. power supply

International Nuclear Information System (INIS)

Matsukawa, Tatsuya; Shioyama, Masanori; Shimada, Katsuhiro; Takaku, Taku; Neumeyer, Charles; Tsuji-Iio, Shunji; Shimada, Ryuichi

2001-01-01

The low aspect ratio spherical torus (ST), which has single turn toroidal field coil, requires the extremely high d.c. current like as 20 MA to energize the coil. Considering the ratings of such extremely high current and low voltage, power-MOSFET element is employed as the switching device for the a.c./d.c. converter of power supply. One of the advantages of power-MOSFET element is low on-state resistance, which is to meet the high current and low voltage operation. Recently, the capacity of power-MOSFET element has been increased and its on-state resistance has been decreased, so that the possibility of construction of high current and low voltage a.c./d.c. converter with parallel connected power-MOSFET elements has been growing. With the aim of developing the high current d.c. power supply using power-MOSFET, the basic characteristics of parallel operation with power-MOSFET elements are experimentally investigated. And, the synchronous rectifier type and the bi-directional self commutated type a.c./d.c. converters using parallel connected power-MOSFET elements are proposed

Measurement of radiation and temperature of cathod spots in excimer laser discharge; Ekishima reza reiki hodennai ni fukumareru inkyoku kiten no kogakuteki kansoku to ondo no sokutei

Energy Technology Data Exchange (ETDEWEB)

Minamitani, Y.; Nakatani, H. [Mitsubishi Electric Corp., Tokyo (Japan)

1996-08-20

Excimer laser is used in various fields such as luminous source for steppers, annealing treatment, ablation process, nuclear fusion and so on. In this paper, the radiation timing and gas temperature of cathode spots, streamer discharges and glow discharges in KrF excimer are measured by observing the radiating spectra thereof. The following conclusions are obtained from the results of the present study. Cathode spots begin to radiate at about 20ns after the discharge initiation, then the first and second radiation peaks are observed respectively when the discharge current reversing after passing zero point and the reserved discharged current approaching zero point. Streamer discharge makes flashover between electrodes at the second radiation peak of cathode spots, while the glow discharges almost disappear when streamer discharges occurring. The temperatures of cathode spots and glow discharge as 5500K and 2600K respectively are almost constant and independent upon the discharging voltage of laser. 14 refs., 12 figs.

Highly-stabilized power supply for synchrotron accelerators. High speed, low ripple power supply

Energy Technology Data Exchange (ETDEWEB)

Sato, Kenji [Osaka Univ., Ibaraki (Japan). Research Center for Nuclear Physics; Kumada, Masayuki; Fukami, Kenji; Koseki, Shoichiro; Kubo, Hiroshi; Kanazawa, Toru

1997-02-01

In synchrotron accelerators, in order to utilize high energy beam effectively, those are operated by repeating acceleration and taking-out at short period. In order to accelerate by maintaining beam track stable, the tracking performance with the error less than 10{sup -3} in the follow-up of current is required for the power supply. Further, in order to maintain the intensity and uniformity of beam when it is taken out, very low ripple is required for output current. The power supply having such characteristics has been developed, and applied to the HIMAC and the SPring-8. As the examples of the application of synchrotrons, the accelerators for medical treatment and the generation of synchrotron radiation are described. As to the power supply for the deflection magnets and quadrupole magnets of synchrotron accelerators, the specifications of the main power supply, the method of reducing ripple, the method of improving tracking, and active filter control are reported. As to the test results, the measurement of current ripple and tracking error is shown. The lowering of ripple was enabled by common mode filter and the symmetrical connection of electromagnets, and high speed response was realized by the compensation for delay with active filter. (K.I.)

Effect of laser-plasma X-ray irradiation on crystallization of amorphous silicon film by excimer laser annealing

International Nuclear Information System (INIS)

Matsuo, Naoto; Uejukkoku, Kazuya; Heya, Akira; Takanashi, Yasuyuki; Amano, Sho; Miyamoto, Shuji; Mochizuki, Takayasu

2007-01-01

The effect of laser plasma soft X-ray (LPX) irradiation on crystallization by excimer laser annealing (ELA) was investigated at low ELA energy densities. The crystalline fraction at energy densities of 50 and 60 mJ/cm 2 for LPX followed by ELA is nearly equal to that at 80 to 100 mJ/cm 2 for the ELA method with non-LPX irradiation. The results obtained indicate that LPX irradiation before ELA reduces the critical energy density for the start of crystallization. The combined method of LPX irradiation and ELA will enable us to realize a low-temperature process for ELA crystallization. (author)

Reactor G1: high power experiments

International Nuclear Information System (INIS)

Laage, F. de; Teste du Baillet, A.; Veyssiere, A.; Wanner, G.

1957-01-01

The experiments carried out in the starting-up programme of the reactor G1 comprised a series of tests at high power, which allowed the following points to be studied: 1- Effect of poisoning by Xenon (absolute value, evolution). 2- Temperature coefficients of the uranium and graphite for a temperature distribution corresponding to heating by fission. 3- Effect of the pressure (due to the coiling system) on the reactivity. 4- Calibration of the security rods as a function of their position in the pile (1). 5- Temperature distribution of the graphite, the sheathing, the uranium and the air leaving the canals, in a pile running normally at high power. 6- Neutron flux distribution in a pile running normally at high power. 7- Determination of the power by nuclear and thermodynamic methods. These experiments have been carried out under two very different pile conditions. From the 1. to the 15. of August 1956, a series of power increases, followed by periods of stabilisation, were induced in a pile containing uranium only, in 457 canals, amounting to about 34 tons of fuel. A knowledge of the efficiency of the control rods in such a pile has made it possible to measure with good accuracy the principal effects at high temperatures, that is, to deal with points 1, 2, 3, 5. Flux charts giving information on the variations of the material Laplacian and extrapolation lengths in the reflector have been drawn up. Finally the thermodynamic power has been measured under good conditions, in spite of some installation difficulties. On September 16, the pile had its final charge of 100 tons. All the canals were loaded, 1,234 with uranium and 53 (i.e. exactly 4 per cent of the total number) with thorium uniformly distributed in a square lattice of 100 cm side. Since technical difficulties prevented the calibration of the control rods, the measurements were limited to the determination of the thermodynamic power and the temperature distributions (points 5 and 7). This report will

Voltage generators of high voltage high power accelerators

International Nuclear Information System (INIS)

Svinin, M.P.

1981-01-01

High voltage electron accelerators are widely used in modern radiation installations for industrial purposes. In the near future further increasing of their power may be effected, which enables to raise the efficiency of the radiation processes known and to master new power-consuming production in industry. Improvement of HV generators by increasing their power and efficiency is one of many scientific and engineering aspects the successful solution of which provides further development of these accelerators and their technical parameters. The subject is discussed in detail. (author)

Optimal Operation of Plug-In Electric Vehicles in Power Systems with High Wind Power Penetrations

DEFF Research Database (Denmark)

Hu, Weihao; Su, Chi; Chen, Zhe

2013-01-01

in the power systems with high wind power penetrations. In this paper, the integration of plug-in electric vehicles in the power systems with high wind power penetrations is proposed and discussed. Optimal operation strategies of PEV in the spot market are proposed in order to decrease the energy cost for PEV......The Danish power system has a large penetration of wind power. The wind fluctuation causes a high variation in the power generation, which must be balanced by other sources. The battery storage based Plug-In Electric Vehicles (PEV) may be a possible solution to balance the wind power variations...... owners. Furthermore, the application of battery storage based aggregated PEV is analyzed as a regulation services provider in the power system with high wind power penetrations. The western Danish power system where the total share of annual wind power production is more than 27% of the electrical energy...

Research & Implementation of AC - DC Converter with High Power Factor & High Efficiency

Directory of Open Access Journals (Sweden)

Hsiou-Hsian Nien

2014-05-01

Full Text Available In this paper, we design and develop a high power factor, high efficiency two-stage AC - DC power converter. This paper proposes a two-stage AC - DC power converter. The first stage is boost active power factor correction circuit. The latter stage is near constant frequency LLC resonant converter. In addition to traditional LLC high efficiency advantages, light-load conversion efficiency of this power converter can be improved. And it possesses high power factor and near constant frequency operating characteristics, can significantly reduce the electromagnetic interference. This paper first discusses the main structure and control manner of power factor correction circuit. And then by the LLC resonant converter equivalent model proceed to circuit analysis to determine the important parameters of the converter circuit elements. Then design a variable frequency resonant tank. The resonant frequency can change automatically on the basis of the load to reach near constant frequency operation and a purpose of high efficiency. Finally, actually design and produce an AC – DC power converter with output of 190W to verify the characteristics and feasibility of this converter. The experimental results show that in a very light load (9.5 W the efficiency is as high as 81%, the highest efficiency of 88% (90 W. Full load efficiency is 87%. At 19 W ~ 190 W power changes, the operating frequency change is only 0.4 kHz (AC 110 V and 0.3 kHz (AC 220 V.

Laser Thomson scattering diagnostics of non-equilibrium high pressure plasmas

International Nuclear Information System (INIS)

Muraoka, K.; Uchino, K.; Bowden, M.D.; Noguchi, Y.

2001-01-01

For various applications of non-equilibrium high pressure plasmas, knowledge of electron properties, such as electron density, electron temperature and/or electron energy distribution function (eedf), is prerequisite for any rational approach to understanding physical and chemical processes occurring in the plasmas. For this purpose, laser Thomson scattering has been successfully applied for the first time to measure the electron properties in plasmas for excimer laser pumping and in microdischarges. Although this diagnostic technique is well established for measurements in high temperature plasmas, its applications to these glow discharge plasmas have had various inherent difficulties, such as a presence of high density neutral particles (>10 21 m -3 ) in the excimer laser pumping discharges and an extremely small plasma size (<0.1 mm) and the presence of nearby walls for microdischarges. These difficulties have been overcome and clear signals have been obtained. The measured results are presented and their implications in the respective discharge phenomena are discussed

High-Bandwidth, High-Efficiency Envelope Tracking Power Supply for 40W RF Power Amplifier Using Paralleled Bandpass Current Sources

DEFF Research Database (Denmark)

Høyerby, Mikkel Christian Wendelboe; Andersen, Michael Andreas E.

2005-01-01

This paper presents a high-performance power conversion scheme for power supply applications that require very high output voltage slew rates (dV/dt). The concept is to parallel 2 switching bandpass current sources, each optimized for its passband frequency space and the expected load current....... The principle is demonstrated with a power supply, designed for supplying a 40 W linear RF power amplifier for efficient amplification of a 16-QAM modulated data stream...

Small high cooling power space cooler

Energy Technology Data Exchange (ETDEWEB)

Nguyen, T. V.; Raab, J.; Durand, D.; Tward, E. [Northrop Grumman Aerospace Systems Redondo Beach, Ca, 90278 (United States)

2014-01-29

The small High Efficiency pulse tube Cooler (HEC) cooler, that has been produced and flown on a number of space infrared instruments, was originally designed to provide cooling of 10 W @ 95 K. It achieved its goal with >50% margin when limited by the 180 W output ac power of its flight electronics. It has also been produced in 2 stage configurations, typically for simultaneously cooling of focal planes to temperatures as low as 35 K and optics at higher temperatures. The need for even higher cooling power in such a low mass cryocooler is motivated by the advent of large focal plane arrays. With the current availability at NGAS of much larger power cryocooler flight electronics, reliable long term operation in space with much larger cooling powers is now possible with the flight proven 4 kg HEC mechanical cooler. Even though the single stage cooler design can be re-qualified for those larger input powers without design change, we redesigned both the linear and coaxial version passive pulse tube cold heads to re-optimize them for high power cooling at temperatures above 130 K while rejecting heat to 300 K. Small changes to the regenerator packing, the re-optimization of the tuned inertance and no change to the compressor resulted in the increased performance at 150 K. The cooler operating at 290 W input power achieves 35 W@ 150 K corresponding to a specific cooling power at 150 K of 8.25 W/W and a very high specific power of 72.5 W/Kg. At these powers the cooler still maintains large stroke, thermal and current margins. In this paper we will present the measured data and the changes to this flight proven cooler that were made to achieve this increased performance.

Gate Drive For High Speed, High Power IGBTs

Energy Technology Data Exchange (ETDEWEB)

Nguyen, M.N.; Cassel, R.L.; de Lamare, J.E.; Pappas, G.C.; /SLAC

2007-06-18

A new gate drive for high-voltage, high-power IGBTs has been developed for the SLAC NLC (Next Linear Collider) Solid State Induction Modulator. This paper describes the design and implementation of a driver that allows an IGBT module rated at 800A/3300V to switch up to 3000A at 2200V in 3{micro}S with a rate of current rise of more than 10000A/{micro}S, while still being short circuit protected. Issues regarding fast turn on, high de-saturation voltage detection, and low short circuit peak current will be presented. A novel approach is also used to counter the effect of unequal current sharing between parallel chips inside most high-power IGBT modules. It effectively reduces the collector-emitter peak current, and thus protects the IGBT from being destroyed during soft short circuit conditions at high di/dt.

Gate Drive For High Speed, High Power IGBTs

International Nuclear Information System (INIS)

Nguyen, M.N.; Cassel, R.L.; de Lamare, J.E.; Pappas, G.C.; SLAC

2007-01-01

A new gate drive for high-voltage, high-power IGBTs has been developed for the SLAC NLC (Next Linear Collider) Solid State Induction Modulator. This paper describes the design and implementation of a driver that allows an IGBT module rated at 800A/3300V to switch up to 3000A at 2200V in 3(micro)S with a rate of current rise of more than 10000A/(micro)S, while still being short circuit protected. Issues regarding fast turn on, high de-saturation voltage detection, and low short circuit peak current will be presented. A novel approach is also used to counter the effect of unequal current sharing between parallel chips inside most high-power IGBT modules. It effectively reduces the collector-emitter peak current, and thus protects the IGBT from being destroyed during soft short circuit conditions at high di/dt

High Power Fiber Laser Test Bed

Data.gov (United States)

Federal Laboratory Consortium — This facility, unique within DoD, power-combines numerous cutting-edge fiber-coupled laser diode modules (FCLDM) to integrate pumping of high power rare earth-doped...

Liquid chromatographic determination of microcystins in water samples following pre-column excimer fluorescence derivatization with 4-(1-pyrene)butanoic acid hydrazide.

Science.gov (United States)

Hayama, Tadashi; Katoh, Kenji; Aoki, Takayoshi; Itoyama, Miki; Todoroki, Kenichiro; Yoshida, Hideyuki; Yamaguchi, Masatoshi; Nohta, Hitoshi

2012-11-28

A method to measure the concentrations of microcystins (MCs) in water samples has been developed by incorporating pre-column fluorescence derivatization and liquid chromatography (LC). A solid-phase extraction for pretreatment was used to extract the MCs in water samples. The MCs were derivatized with excimer-forming 4-(1-pyrene)butanoic acid hydrazide (PBH). The MCs could then be detected by fluorescence after separation with a pentafluorophenyl (PFP)-modified superficially porous (core shell) particle LC column. The derivatization reactions of MCs with PBH proceeded easily in the presence of 4,6-dimethoxy-1,3,5-triazin-2-yl-4-methylmorpholinium (DMT-MM) as a condensation reagent, and the resulting derivatives could be easily separated on the PFP column. The derivatives were selectively detected at excimer fluorescence wavelengths (440-540 nm). The instrument detection limit and the instrument quantification limit of the MCs standards were 0.4-1.2 μg L(-1) and 1.4-3.9 μg L(-1), respectively. The method was validated at 0.1 and 1.0 μg L(-1) levels in tap and pond water samples, and the recovery of MCs was between 67 and 101% with a relative standard deviation of 11%. The proposed method can be used to quantify trace amounts of MCs in water samples. Copyright © 2012 Elsevier B.V. All rights reserved.

High average-power induction linacs

International Nuclear Information System (INIS)

Prono, D.S.; Barrett, D.; Bowles, E.

1989-01-01

Induction linear accelerators (LIAs) are inherently capable of accelerating several thousand amperes of /approximately/ 50-ns duration pulses to > 100 MeV. In this paper we report progress and status in the areas of duty factor and stray power management. These technologies are vital if LIAs are to attain high average power operation. 13 figs

Design of The High Efficiency Power Factor Correction Circuit for Power Supply

Directory of Open Access Journals (Sweden)

Atiye Hülya OBDAN

2017-12-01

Full Text Available Designing power factor correction circuits for switched power supplies has become important in recent years in terms of efficient use of energy. Power factor correction techniques play a significant role in high power density and energy efficiency. For these purposes, bridgeless PFC topologies and control strategies have been developed alongside basic boost PFC circuits. The power density can be increased using bridgeless structures by means of reducing losses in the circuit. This article examines bridgeless PFC structures and compares their performances in terms of losses and power factor. A semi-bridgeless PFC, which is widely used at high power levels, was analyzed and simulated. The designed circuit simulation using the current mode control method was performed in the PSIM program. A prototype of a 900 W semi-bridgeless PFC circuit was implemented and the results obtained from the circuit are presented

The effect of excimer laser pretreatment on diffusion and activation of boron implanted in silicon

International Nuclear Information System (INIS)

Monakhov, E.V.; Svensson, B.G.; Linnarsson, M.K.; La Magna, A.; Italia, M.; Privitera, V.; Fortunato, G.; Cuscuna, M.; Mariucci, L.

2005-01-01

We have investigated the effect of excimer laser annealing (ELA) on transient enhanced diffusion (TED) and activation of boron implanted in Si during subsequent rapid thermal annealing (RTA). It is observed that ELA with partial melting of the implanted region causes reduction of TED in the region that remains solid during ELA, where the diffusion length of boron is reduced by a factor of ∼4 as compared to the as-implanted sample. This is attributed to several mechanisms such as liquid-state annealing of a fraction of the implantation induced defects, introduction of excess vacancies during ELA, and solid-state annealing of the defects beyond the maximum melting depth by the heat wave propagating into the Si wafer. The ELA pretreatment provides a substantially improved electrical activation of boron during subsequent RTA

A high frequency, high power CARM proposal for the DEMO ECRH system

International Nuclear Information System (INIS)

Mirizzi, Francesco; Spassovsky, Ivan; Ceccuzzi, Silvio; Dattoli, Giuseppe; Di Palma, Emanuele; Doria, Andrea; Gallerano, Gianpiero; Lampasi, Alessandro; Maffia, Giuseppe; Ravera, GianLuca; Sabia, Elio; Tuccillo, Angelo Antonio; Zito, Pietro

2015-01-01

Highlights: • ECRH system for DEMO. • Cyclotron Auto-Resonance Maser (CARM) devices. • Relativistic electron beams. • Bragg reflectors. • High voltage pulse modulators. - Abstract: ECRH&CD systems are extensively used on tokamak plasmas due to their capability of highly tailored power deposition, allowing very localised heating and non-inductive current drive, useful for MHD and profiles control. The high electron temperatures expected in DEMO will require ECRH systems with operating frequency in the 200–300 GHz range, equipped with a reasonable number of high power (P ≥ 1 MW) CW RF sources, for allowing central RF power deposition. In this frame the ENEA Fusion Department (Frascati) is coordinating a task force aimed at the study and realisation of a suitable high power, high frequency reliable source.

A high frequency, high power CARM proposal for the DEMO ECRH system

Energy Technology Data Exchange (ETDEWEB)

Mirizzi, Francesco, E-mail: francesco.mirizzi@enea.it [Consorzio CREATE, Via Claudio 21, I-80125 Napoli (Italy); Spassovsky, Ivan [Unità Tecnica Applicazioni delle Radiazioni – ENEA, C.R. Frascati, via E. Fermi 45, I-00044 Frascati (Italy); Ceccuzzi, Silvio [Unità Tecnica Fusione – ENEA C. R. Frascati, via E. Fermi 45, 00044 Frascati, Roma (Italy); Dattoli, Giuseppe; Di Palma, Emanuele; Doria, Andrea; Gallerano, Gianpiero [Unità Tecnica Applicazioni delle Radiazioni – ENEA, C.R. Frascati, via E. Fermi 45, I-00044 Frascati (Italy); Lampasi, Alessandro; Maffia, Giuseppe; Ravera, GianLuca [Unità Tecnica Fusione – ENEA C. R. Frascati, via E. Fermi 45, 00044 Frascati, Roma (Italy); Sabia, Elio [Unità Tecnica Applicazioni delle Radiazioni – ENEA, C.R. Frascati, via E. Fermi 45, I-00044 Frascati (Italy); Tuccillo, Angelo Antonio; Zito, Pietro [Unità Tecnica Fusione – ENEA C. R. Frascati, via E. Fermi 45, 00044 Frascati, Roma (Italy)

2015-10-15

Highlights: • ECRH system for DEMO. • Cyclotron Auto-Resonance Maser (CARM) devices. • Relativistic electron beams. • Bragg reflectors. • High voltage pulse modulators. - Abstract: ECRH&CD systems are extensively used on tokamak plasmas due to their capability of highly tailored power deposition, allowing very localised heating and non-inductive current drive, useful for MHD and profiles control. The high electron temperatures expected in DEMO will require ECRH systems with operating frequency in the 200–300 GHz range, equipped with a reasonable number of high power (P ≥ 1 MW) CW RF sources, for allowing central RF power deposition. In this frame the ENEA Fusion Department (Frascati) is coordinating a task force aimed at the study and realisation of a suitable high power, high frequency reliable source.

High average-power induction linacs

International Nuclear Information System (INIS)

Prono, D.S.; Barrett, D.; Bowles, E.; Caporaso, G.J.; Chen, Yu-Jiuan; Clark, J.C.; Coffield, F.; Newton, M.A.; Nexsen, W.; Ravenscroft, D.; Turner, W.C.; Watson, J.A.

1989-01-01

Induction linear accelerators (LIAs) are inherently capable of accelerating several thousand amperes of ∼ 50-ns duration pulses to > 100 MeV. In this paper the authors report progress and status in the areas of duty factor and stray power management. These technologies are vital if LIAs are to attain high average power operation. 13 figs

Current status of pulse-power technology and applications at LBT, Nagaoka

International Nuclear Information System (INIS)

Yatsui, K.; Masuda, W.; Masugata, K.; Jiang, W.; Sekimoto, Y.; Imada, G.; Sonegawa, T.; Kang, X.D.

1993-01-01

Tight focusing of an ion beam was obtained by open-quotes Plasma Focus Diodeclose quotes. In addition to two-dimensionally line-focusing reported previously, the authors achieved point focusing of the proton beam. Quick charging Blumlein PFL was successfully developed. Using saturable cores as a charging inductor, the authors succeeded in the reduction of prepulse and quick charging of the Blumlein line. Output pulse of voltage ∼580 kV and current ∼24 kA with current rise time of less than 16 ns. Various thin films were quickly prepared by Ion-Beam Evaporation (IBE) such as ZnS, YBCO, BaTiO 3 , BN, B, C, ITO, apatite, etc. Basic characteristics were studied of ablation plasma produced by the irradiation of ion beam on the targets. Highly-repetitive excimer laser with subsonic gas flow is developed by Ludwieg charge tube. Basic characteristics of gas dynamics are studied by simulation. The authors developed a new circuit to excite highly-repetitive excimer lasers, where a saturable transformer is used in magnetic pulse compressor. To control lightning artificially, they studied basic plasma channel produced by TEA-CO 2 lasers in air

High power gyrotrons: a close perspective

International Nuclear Information System (INIS)

Kartikeyan, M.V.

2012-01-01

Gyrotrons and their variants, popularly known as gyrodevices are millimetric wave sources provide very high powers ranging from long pulse to continuous wave (CW) for various technological, scientific and industrial applications. From their conception (monotron-version) in the late fifties until their successful development for various applications, these devices have come a long way technologically and made an irreversible impact on both users and developers. The possible applications of high power millimeter and sub-millimeter waves from gyrotrons and their variants (gyro-devices) span a wide range of technologies. The plasma physics community has already taken advantage of the recent advances of gyrotrons in the areas of RF plasma production, heating, non-inductive current drive, plasma stabilization and active plasma diagnostics for magnetic confinement thermonuclear fusion research, such as lower hybrid current drive (LHCD) (8 GHz), electron cyclotron resonance heating (ECRH) (28-170-220 GHz), electron cyclotron current drive (ECCD), collective Thomson scattering (CTS), heat-wave propagation experiments, and space-power grid (SPG) applications. Other important applications of gyrotrons are electron cyclotron resonance (ECR) discharges for the generation of multi- charged ions and soft X-rays, as well as industrial materials processing and plasma chemistry. Submillimeter wave gyrotrons are employed in high frequency, broadband electron paramagnetic resonance (EPR) spectroscopy. Additional future applications await the development of novel high power gyro-amplifiers and devices for high resolution radar ranging and imaging in atmospheric and planetary science as well as deep space and specialized satellite communications, RF drivers for next generation high gradient linear accelerators (supercolliders), high resolution Doppler radar, radar ranging and imaging in atmospheric and planetary science, drivers for next-generation high-gradient linear accelerators

High voltage generator circuit with low power and high efficiency applied in EEPROM

International Nuclear Information System (INIS)

Liu Yan; Zhang Shilin; Zhao Yiqiang

2012-01-01

This paper presents a low power and high efficiency high voltage generator circuit embedded in electrically erasable programmable read-only memory (EEPROM). The low power is minimized by a capacitance divider circuit and a regulator circuit using the controlling clock switch technique. The high efficiency is dependent on the zero threshold voltage (V th ) MOSFET and the charge transfer switch (CTS) charge pump. The proposed high voltage generator circuit has been implemented in a 0.35 μm EEPROM CMOS process. Measured results show that the proposed high voltage generator circuit has a low power consumption of about 150.48 μW and a higher pumping efficiency (83.3%) than previously reported circuits. This high voltage generator circuit can also be widely used in low-power flash devices due to its high efficiency and low power dissipation. (semiconductor integrated circuits)

Optical Fiber for High-Power Optical Communication

Directory of Open Access Journals (Sweden)

Kenji Kurokawa

2012-09-01

Full Text Available We examined optical fibers suitable for avoiding such problems as the fiber fuse phenomenon and failures at bends with a high power input. We found that the threshold power for fiber fuse propagation in photonic crystal fiber (PCF and hole-assisted fiber (HAF can exceed 18 W, which is more than 10 times that in conventional single-mode fiber (SMF. We considered this high threshold power in PCF and HAF to be caused by a jet of high temperature fluid penetrating the air holes. We showed examples of two kinds of failures at bends in conventional SMF when the input power was 9 W. We also observed the generation of a fiber fuse under a condition that caused a bend-loss induced failure. We showed that one solution for the failures at bends is to use optical fibers with a low bending loss such as PCF and HAF. Therefore, we consider PCF and HAF to be attractive solutions to the problems of the fiber fuse phenomenon and failures at bends with a high power input.

Suppression of dewetting phenomena during excimer laser melting of thin metal films on SiO2

International Nuclear Information System (INIS)

Kline, J.E.; Leonard, J.P.

2005-01-01

Pulsed excimer laser irradiation has been used to fully melt 200 nm films of elemental Au and Ni on SiO 2 substrates. With the use of a capping layer of SiO 2 and line irradiation via projection optics, the typical liquid-phase dewetting processes associated with these metals on SiO 2 has been suppressed. In a series of experiments varying line widths and fluence, a process region is revealed immediately above the complete melting threshold for which the films remain continuous and smooth after melting and resolidification. Simple energetic arguments for mechanisms leading to initiation of dewetting support these observations, and a gas-mediated model is proposed to describe the process conditions that are necessary for the suppression of dewetting

Workshop on High Power ICH Antenna Designs for High Density Tokamaks

Science.gov (United States)

Aamodt, R. E.

1990-02-01

A workshop in high power ICH antenna designs for high density tokamaks was held to: (1) review the data base relevant to the high power heating of high density tokamaks; (2) identify the important issues which need to be addressed in order to ensure the success of the ICRF programs on CIT and Alcator C-MOD; and (3) recommend approaches for resolving the issues in a timely realistic manner. Some specific performance goals for the antenna system define a successful design effort. Simply stated these goals are: couple the specified power per antenna into the desired ion species; produce no more than an acceptable level of RF auxiliary power induced impurities; and have a mechanical structure which safely survives the thermal, mechanical and radiation stresses in the relevant environment. These goals are intimately coupled and difficult tradeoffs between scientific and engineering constraints have to be made.

The NASA CSTI High Capacity Power Project

International Nuclear Information System (INIS)

Winter, J.; Dudenhoefer, J.; Juhasz, A.; Schwarze, G.; Patterson, R.; Ferguson, D.; Schmitz, P.; Vandersande, J.

1992-01-01

This paper describes the elements of NASA's CSTI High Capacity Power Project which include Systems Analysis, Stirling Power Conversion, Thermoelectric Power Conversion, Thermal Management, Power Management, Systems Diagnostics, Environmental Interactions, and Material/Structural Development. Technology advancement in all elements is required to provide the growth capability, high reliability and 7 to 10 year lifetime demanded for future space nuclear power systems. The overall project will develop and demonstrate the technology base required to provide a wide range of modular power systems compatible with the SP-100 reactor which facilitates operation during lunar and planetary day/night cycles as well as allowing spacecraft operation at any attitude or distance from the sun. Significant accomplishments in all of the project elements will be presented, along with revised goals and project timeliness recently developed

One-kilohertz eye tracker and active intraoperative torsion detection in the NIDEK CXIII and Quest excimer lasers.

Science.gov (United States)

Waring, George O

2009-10-01

To describe recent technological additions to the NIDEK CXIII and Quest excimer lasers. A summary article with data from previous published studies outlining the benefits of newer technology. The addition of a 1-kHz infrared eye tracker decreased the spread of laser spot placement from a mean of 228.79 microm without a tracker to 38.47 microm with the eye tracker. The addition of real-time torsion error correction produced a statistically significantly lower cylinder dispersion, mean manifest refractive cylinder, and error of angle postoperatively in eyes that underwent LASIK. The incorporation of an ultrahigh speed eye tracker and active cyclotorsion correction surpasses the minimal technology criteria required for accurate wavefront-based ablations. Copyright 2009, SLACK Incorporated.

Singlet Fission and Excimer Formation in Disordered Solids of Alkyl-Substituted 1,3-Diphenylisobenzofurans.

Science.gov (United States)

Dron, Paul I; Michl, Josef; Johnson, Justin C

2017-11-16

We describe the preparation and excited state dynamics of three alkyl derivatives of 1,3-diphenylisobenzofuran (1) in both solutions and thin films. The substitutions are intended to disrupt the slip-stacked packing observed in crystals of 1 while maintaining the favorable energies of singlet and triplet for singlet fission (SF). All substitutions result in films that are largely amorphous as judged by the absence of strong X-ray diffraction peaks. The films of 1 carrying a methyl in the para position of one phenyl ring undergo SF relatively efficiently (≥75% triplet yield, Φ T ) but more slowly than thin films of 1. When the methyl is replaced with a t-butyl, kinetic competition in the excited state favors excimer formation rather than SF (Φ T = 55%). When t-Bu groups are placed in both meta positions of the phenyl substituent, SF is slowed further and Φ T = 35%.

A novel power source for high-precision, highly efficient micro w-EDM

International Nuclear Information System (INIS)

Chen, Shun-Tong; Chen, Chi-Hung

2015-01-01

The study presents the development of a novel power source for high-precision, highly efficient machining of micropart microstructures using micro wire electrical discharge machining (w-EDM). A novel power source based on a pluri resistance–capacitance (pRC) circuit that can generate a high-frequency, high-peak current with a short pulse train is proposed and designed to enhance the performance of micro w-EDM processes. Switching between transistors is precisely controlled in the designed power source to create a high-frequency short-pulse train current. Various microslot cutting tests in both aluminum and copper alloys are conducted. Experimental results demonstrate that the pRC power source creates instant spark erosion resulting in markedly less material for removal, diminishing discharge crater size, and consequently an improved surface finish. A new evaluation approach for spark erosion ability (SEA) to assess the merits of micro EDM power sources is also proposed. In addition to increasing the speed of micro w-EDM by increasing wire feed rates by 1.6 times the original feed rate, the power source is more appropriate for machining micropart microstructures since there is less thermal breaking. Satisfactory cutting of an elaborate miniature hook-shaped structure and a high-aspect ratio microstructure with a squared-pillar array also reveal that the developed pRC power source is effective, and should be very useful in the manufacture of intricate microparts. (paper)

Temperature Stabilized Characterization of High Voltage Power Supplies

CERN Document Server

Krarup, Ole

2017-01-01

High precision measurements of the masses of nuclear ions in the ISOLTRAP experiment relies on an MR-ToF. A major source of noise and drift is the instability of the high voltage power supplies employed. Electrical noise and temperature changes can broaden peaks in time-of-flight spectra and shift the position of peaks between runs. In this report we investigate how the noise and drift of high-voltage power supplies can be characterized. Results indicate that analog power supplies generally have better relative stability than digitally controlled ones, and that the high temperature coefficients of all power supplies merit efforts to stabilize them.

Study on the surface chemical properties of UV excimer laser irradiated polyamide by XPS, ToF-SIMS and CFM

International Nuclear Information System (INIS)

Yip, Joanne; Chan, Kwong; Sin, Kwan Moon; Lau, Kai Shui

2002-01-01

Polyamide (nylon 6) was irradiated by a pulsed ultraviolet (UV) excimer laser with a fluence below its ablation threshold. Chemical modifications on laser treated nylon were studied by X-ray photoelectron spectroscopy (XPS), time-of-flight secondary ion mass spectrometry (Tof-SIMS) and chemical force microscopy (CFM). XPS study provides information about changes in chemical composition and the chemical-state of atom types on the fiber surface. The high sensitivity of ToF-SIMS to the topmost layers was used to detect crosslinking after the laser treatment. Gold-coated AFM tips modified with -COOH terminated self-assembled alkanethiol monolayers (SAMs) were used to measure adhesion forces on the untreated and laser treated samples. XPS results revealed that the irradiated samples have higher oxygen content than prior to laser irradiation. Tof-SIMS analysis illustrated that carbonyl groups in nylon 6 decrease significantly but hydroxyl groups increase after low-fluence laser irradiation. The adhesion force measurements by CFM showed spatial distribution of hydroxyl groups on nylon 6 after the laser treatment

Does imiquimod pretreatment optimize 308-nm excimer laser (UVB) therapy in psoriasis patients?

Science.gov (United States)

Tacastacas, Joselin D; Oyetakin-White, Patricia; Soler, David C; Young, Andrew; Groft, Sarah; Honda, Kord; Cooper, Kevin D; McCormick, Thomas S

2017-07-01

Psoriasis continues to be a debilitating skin disease affecting 1-3% of the United States population. Although the effectiveness of several current biologic therapies have described this pathology as a IL-23, TNF-a and Th17-mediated disease, less invasive approaches are still in use and in need of refinement. One of these is the usage of narrow band-UVB (NB-UVB) therapy to deplete specifically intra-epidermal CD3+, CD4+ and CD8+ cells to clear psoriatic plaques. In order to improve NB-UVB therapy, we sought to determine whether skin pre-treatment with the TLR7 agonist imiquimod (IMQ) would help increase the efficiency of the former at resolving psoriatic plaques. Eucerin ® Original Moisturizing Lotion (topical vehicle) or Aldara ® (imiquimod 5% topical cream) were applied for 5 days once daily to a maximum contiguous area of 25 cm 2 (5 cm × 5 cm area). Patients were provided with sachets containing 12.5 mg of imiquimod each and were instructed to apply imiquimod (I) to two psoriasis plaques (5 sachets of imiquimod allotted to each plaque). A PHAROS excimer Laser EX-308 (Ra Medical Systems, Inc. Carlsbad, CA, USA) with an output of monochromatic 308-nm light and pulse width of 20-50 ns was used for all patients. Punch biopsies of psoriatic lesions (6 mm) were taken at 4 and 48 h after final application of topical treatment with or without excimer laser treatment. Real-time quantitative RT-PCR was performed according to manufacturer's instructions and Inmunohistochemistry was used as described before. Our results suggests that although IMQ seemed to activate the type I interferon pathway as previously described, its concomitant usage with NB-UVB for clearing psoriatic skin was ineffective. Although upregulation of genes MxA, GRAMD1A and DMXL2 suggested that IMQ treatment did induce skin changes in psoriasis patients, more optimal dosing of IMQ and NB-UVB might be necessary to achieve desired treatment responses. The observation that psoriasis involvement was not

High power diode lasers converted to the visible

DEFF Research Database (Denmark)

Jensen, Ole Bjarlin; Hansen, Anders Kragh; Andersen, Peter E.

2017-01-01

High power diode lasers have in recent years become available in many wavelength regions. However, some spectral regions are not well covered. In particular, the visible spectral range is lacking high power diode lasers with good spatial quality. In this paper, we highlight some of our recent...... results in nonlinear frequency conversion of high power near infrared diode lasers to the visible spectral region....

Measurement of high-power microwave pulse under intense ...

Indian Academy of Sciences (India)

Abstract. KALI-1000 pulse power system has been used to generate single pulse nanosecond duration high-power microwaves (HPM) from a virtual cathode oscillator. (VIRCATOR) device. HPM power measurements were carried out using a transmitting– receiving system in the presence of intense high frequency (a few ...

Workshop on high power ICH antenna designs for high density tokamaks

International Nuclear Information System (INIS)

Aamodt, R.E.

1990-01-01

A workshop in high power ICH antenna designs for high density tokamaks was held in Boulder, Colorado on January 31 through February 2, 1990. The purposes of the workshop were to: (1) review the data base relevant to the high power heating of high density tokamaks; (2) identify the important issues which need to be addressed in order to ensure the success of the ICRF programs on CIT and Alcator C-MOD; and (3) recommend approaches for resolving the issues in a timely realistic manner. Some specific performance goals for the antenna system define a successful design effort. Simply stated these goals are: couple the specified power per antenna into the desired ion species; produce no more than an acceptable level of rf auxiliary power induced impurities; and have a mechanical structure which safely survives the thermal, mechanical and radiation stresses in the relevant environment. These goals are intimately coupled and difficult tradeoffs between scientific and engineering constraints have to be made

Lasers '89

International Nuclear Information System (INIS)

Harris, D.G.; Shay, T.M.

1990-01-01

This book covers the following topics: XUV, X-Ray and Gamma-Ray Lasers, excimer lasers, chemical lasers, nuclear pumped lasers, high power gas lasers, solid state lasers, laser spectroscopy. The paper presented include: Development of KrF lasers for fusion and Nuclear driven solid-state lasers

High-power sputtering employed for film deposition

International Nuclear Information System (INIS)

Shapovalov, V I

2017-01-01

The features of high-power magnetron sputtering employed for the films’ deposition are reviewed. The main physical phenomena accompanying high-power sputtering including ion-electron emission, gas rarefaction, ionization of sputtered atoms, self-sputtering, ion sound waves and the impact of the target heating are described. (paper)

Gingin High Optical Power Test Facility

International Nuclear Information System (INIS)

Zhao, C; Blair, D G; Barrigo, P

2006-01-01

The Australian Consortium for Gravitational Wave Astronomy (ACIGA) in collaboration with LIGO is developing a high optical power research facility at the AIGO site, Gingin, Western Australia. Research at the facility will provide solutions to the problems that advanced gravitational wave detectors will encounter with extremely high optical power. The problems include thermal lensing and parametric instabilities. This article will present the status of the facility and the plan for the future experiments

E-beam high voltage switching power supply

Science.gov (United States)

Shimer, Daniel W.; Lange, Arnold C.

1997-01-01

A high power, solid state power supply is described for producing a controllable, constant high voltage output under varying and arcing loads suitable for powering an electron beam gun or other ion source. The present power supply is most useful for outputs in a range of about 100-400 kW or more. The power supply is comprised of a plurality of discrete switching type dc-dc converter modules, each comprising a voltage regulator, an inductor, an inverter for producing a high frequency square wave current of alternating polarity, an improved inverter voltage clamping circuit, a step up transformer, and an output rectifier for producing a dc voltage at the output of each module. The inputs to the converter modules are fed from a common dc rectifier/filter and are linked together in parallel through decoupling networks to suppress high frequency input interactions. The outputs of the converter modules are linked together in series and connected to the input of the transmission line to the load through a decoupling and line matching network. The dc-dc converter modules are phase activated such that for n modules, each module is activated equally 360.degree./n out of phase with respect to a successive module. The phased activation of the converter modules, combined with the square current waveforms out of the step up transformers, allows the power supply to operate with greatly reduced output capacitance values which minimizes the stored energy available for discharge into an electron beam gun or the like during arcing. The present power supply also provides dynamic response to varying loads by controlling the voltage regulator duty cycle using simulated voltage feedback signals and voltage feedback loops. Circuitry is also provided for sensing incipient arc currents reflected at the output of the power supply and for simultaneously decoupling the power supply circuitry from the arcing load.

E-beam high voltage switching power supply

International Nuclear Information System (INIS)

Shimer, D.W.; Lange, A.C.

1997-01-01

A high power, solid state power supply is described for producing a controllable, constant high voltage output under varying and arcing loads suitable for powering an electron beam gun or other ion source. The present power supply is most useful for outputs in a range of about 100-400 kW or more. The power supply is comprised of a plurality of discrete switching type dc-dc converter modules, each comprising a voltage regulator, an inductor, an inverter for producing a high frequency square wave current of alternating polarity, an improved inverter voltage clamping circuit, a step up transformer, and an output rectifier for producing a dc voltage at the output of each module. The inputs to the converter modules are fed from a common dc rectifier/filter and are linked together in parallel through decoupling networks to suppress high frequency input interactions. The outputs of the converter modules are linked together in series and connected to the input of the transmission line to the load through a decoupling and line matching network. The dc-dc converter modules are phase activated such that for n modules, each module is activated equally 360 degree/n out of phase with respect to a successive module. The phased activation of the converter modules, combined with the square current waveforms out of the step up transformers, allows the power supply to operate with greatly reduced output capacitance values which minimizes the stored energy available for discharge into an electron beam gun or the like during arcing. The present power supply also provides dynamic response to varying loads by controlling the voltage regulator duty cycle using simulated voltage feedback signals and voltage feedback loops. Circuitry is also provided for sensing incipient arc currents reflected at the output of the power supply and for simultaneously decoupling the power supply circuitry from the arcing load. 7 figs

Contrasting the beam interaction characteristics of selected lasers with a partially stabilized zirconia bio-ceramic

International Nuclear Information System (INIS)

Lawrence, J.

2002-01-01

Differences in the beam interaction characteristics of a CO 2 laser, a Nd:YAG laser, a high power diode laser (HPDL) and an excimer laser with a partially stabilized zirconia bio-ceramic have been studied. A derivative of Beer-Lambert's law was applied and the laser beam absorption lengths of the four lasers were calculated as 33.55x10 -3 cm for the CO 2 laser, 18.22x10 -3 cm for the Nd : YAG laser, 17.17x10 -3 cm for the HPDL and 8.41x10 -6 cm for the excimer laser. It was determined graphically that the fluence threshold values at which significant material removal was effected by the CO 2 laser, the Nd:YAG laser, the HPDL and the excimer laser were 52 J cm -2 , 97 J cm -2 , 115 J cm -2 and 0.48 J cm -2 , respectively. The thermal loading value for the CO 2 laser, the Nd : YAG laser, the HPDL and the excimer laser were calculated as being 1.55 kJ cm -3 , 5.32 kJ cm 3 , 6.69 kJ cm -3 and 57.04 kJ cm -3 , respectively. (author)

High Power laser power conditioning system new discharge circuit research

CERN Document Server

Li Yi; Peng Han Sheng; Zhou Pei Zhang; Zheng Wan Guo; Guo Lang Fu; Chen Li Hua; Chen De Hui; Lai Gui You; Luan Yong Ping

2002-01-01

The new discharge circuit of power conditioning system for high power laser is studied. The theoretical model of the main discharge circuit is established. The pre-ionization circuit is studied in experiment. In addition, the explosion energy of the new large xenon lamp is successfully measured. The conclusion has been applied to 4 x 2 amplifier system

Chaos in high-power high-frequency gyrotrons

International Nuclear Information System (INIS)

Airila, M.

2004-01-01

Gyrotron interaction is a complex nonlinear dynamical process, which may turn chaotic in certain circumstances. The emergence of chaos renders dynamical systems unpredictable and causes bandwidth broadening of signals. Such effects would jeopardize the prospect of advanced gyrotrons in fusion. Therefore, it is important to be aware of the possibility of chaos in gyrotrons. There are three different chaos scenarios closely related to the development of high-power gyrotrons: First, the onset of chaos in electron trajectories would lead to difficulties in the design and efficient operation of depressed potential collectors, which are used for efficiency enhancement. Second, the radio-frequency signal could turn chaotic, decreasing the output power and the spectral purity of the output signal. As a result, mode conversion, transmission, and absorption efficiencies would be reduced. Third, spatio-temporal chaos in the resonator field structure can set a limit for the use of large-diameter interaction cavities and high-order TE modes (large azimuthal index) allowing higher generated power. In this thesis, the issues above are addressed with numerical modeling. It is found that chaos in electron residual energies is practically absent in the parameter region corresponding to high efficiency. Accordingly, depressed collectors are a feasible solution also in advanced high-power gyrotrons. A new method is presented for straightforward numerical solution of the one-dimensional self-consistent time-dependent gyrotron equations, and the method is generalized to two dimensions. In 1D, a chart of gyrotron oscillations is calculated. It is shown that the regions of stationary oscillations, automodulation, and chaos have a complicated topology in the plane of generalized gyrotron variables. The threshold current for chaotic oscillations exceeds typical operating currents by a factor of ten. However, reflection of the output signal may significantly lower the threshold. 2D

Topography-guided hyperopic and hyperopic astigmatism femtosecond laser-assisted LASIK: long-term experience with the 400 Hz eye-Q excimer platform

Directory of Open Access Journals (Sweden)

Kanellopoulos AJ

2012-06-01

Full Text Available Anastasios John KanellopoulosDepartment of Ophthalmology, New York University Medical School, New York, NY, and LaserVision.gr Eye Institute, Athens, GreeceBackground: The purpose of this study was to evaluate the safety and efficacy of topography-guided ablation using the WaveLight 400 Hz excimer laser in laser-assisted in situ keratomileusis (LASIK for hyperopia and/or hyperopic astigmatism.Methods: We prospectively evaluated 208 consecutive LASIK cases for hyperopia with or without astigmatism using the topography-guided platform of the 400 Hz Eye-Q excimer system. The mean preoperative sphere value was +3.04 ± 1.75 (range 0.75–7.25 diopters (D and the mean cylinder value was –1.24 ± 1.41 (–4.75–0 D. Flaps were created either with Intralase FS60 (AMO, Irvine, CA or FS200 (Alcon, Fort Worth, TX femtosecond lasers. Parameters evaluated included age, preoperative and postoperative refractive error, uncorrected distance visual acuity, corrected distance visual acuity, flap diameter and thickness, topographic changes, higher order aberration changes, and low contrast sensitivity. These measurements were repeated postoperatively at regular intervals for at least 24 months.Results: Two hundred and two eyes were available for follow-up at 24 months. Uncorrected distance visual acuity improved from 5.5/10 to 9.2/10. At 24 (8–37 months, 75.5% of the eyes were in the ±0.50 D range and 94.4% were in the ±1.00 D range of the refractive goal. Postoperatively, the mean sphere value was –0.39 ± 0.3 and the cylinder value was –0.35 ± 0.25. Topographic evidence showed that ablation was made in the visual axis and not in the center of the cornea, thus correlating with the angle kappa. No significant complications were encountered in this small group of patients.Conclusion: Hyperopic LASIK utilizing the topography-guided platform of the 400 Hz Eye-Q Allegretto excimer and a femtosecond laser flap appears to be safe and effective for

Effects of DC gate and drain bias stresses on the degradation of excimer laser crystallized polysilicon thin film transistors

International Nuclear Information System (INIS)

Kouvatsos, D N; Michalas, L; Voutsas, A T; Papaioannou, G J

2005-01-01

The effects of gate and drain bias stresses on thin film transistors fabricated in polysilicon films crystallized using the advanced sequential lateral solidification excimer laser annealing (SLS ELA) process, which yields very elongated polysilicon grains and allows the fabrication of TFTs without grain boundary barriers to current flow, are investigated as a function of the active layer thickness and of the TFT orientation relative to the grains. The application of hot carrier stress, with a condition of V GS = V DS /2, was determined to induce threshold voltage, subthreshold swing and transconductance degradation for TFTs in thicker polysilicon films and the associated stress-induced increase in the active layer trap density was evaluated. However, this device degradation was drastically reduced for TFTs fabricated in ultra-thin films. Furthermore, the application of the same stress condition to TFTs oriented vertically to the elongated grains resulted in similar threshold voltage shift but in substantially decreased subthreshold swing and transconductance degradation. The immunity of ultra-thin active layer devices to degradation under hot carrier stress clearly suggests the implementation of ultra thin SLS ELA polysilicon films for the fabrication of TFTs exhibiting not only high performance but, especially, the high reliability needed for integrated systems on panel

Atmospheric Propagation and Combining of High-Power Lasers

Science.gov (United States)

2015-09-08

Brightness-scaling potential of actively phase- locked solid state laser arrays,” IEEE J. Sel. Topics Quantum Electron., vol. 13, no. 3, pp. 460–472, May...attempting to phase- lock high-power lasers, which is not encountered when phase- locking low-power lasers, for example mW power levels. Regardless, we...technology does not currently exist. This presents a challenging problem when attempting to phase- lock high-power lasers, which is not encountered when

Transient analysis of the output short-circuit fault of high power and high voltage DC power supply

International Nuclear Information System (INIS)

Yang Zhigang; Zhang Jian; Huang Yiyun; Hao Xu; Sun Haozhang; Guo Fei

2014-01-01

The transient conditions of output short-circuit fault of high voltage DC power supply was introduced, and the energy of power supply injecting into klystron during the protection process of three-electrode gas switch were analyzed and calculated in detail when klystron load happening electrode arc faults. The results of calculation and simulation are consistent with the results of the experiment. When the output short-circuit fault of high voltage power supply occurs, switch can be shut off in the microsecond, and the short circuit current can be controlled in 200 A. It has verified the rapidity and reliability of the three-electrode gas switch protection, and it has engineering application value. (authors)

Design and development of power supplies for high power IOT based RF amplifier

International Nuclear Information System (INIS)

Kumar, Yashwant; Kumari, S.; Ghosh, M.K.; Bera, A.; Sadhukhan, A.; Pal, S.S.; Khare, V.K.; Tiwari, T.P.; Thakur, S.K.; Saha, S.

2013-01-01

Design, development, circuit topology, function of system components and key system specifications of different power supplies for biasing electrodes of Thales Inductive Output Tube (IOT) based high power RF amplifier are presented in this paper. A high voltage power supply (-30 kV, 3.2A dc) with fast (∼microsecond) crowbar protection circuit is designed, developed and commissioned at VECC for testing the complete setup. Other power supplies for biasing grid electrode (300V, 0.5A dc) and Ion Pump (3 kV, 0.1mA dc) of IOT are also designed, developed and tested with actual load. A HV Deck (60kV Isolation) is specially designed in house to place these power supplies which are floating at 30 kV. All these power supplies are powered by an Isolation Transformer (5 kVA, 60 kV isolation) designed and developed in VECC. (author)

Micelle-assisted signaling of peracetic acid by the oxidation of pyreneboronic acid via monomer-excimer switching.

Science.gov (United States)

Choi, Jiyoung; Lee, Hyo Jin; Cho, Min Jeoung; Chang, Suk-Kyu

2015-08-15

A simple fluorescent probe for the industrial oxidant peracetic acid (PAA) was investigated. PAA-assisted oxidative conversion of pyrene-1-boronic acid into 1-hydroxypyrene was used as the signaling tool. Pyreneboronic acid was found to display selective signaling behavior, being more responsive to PAA than to other commonly used practical oxidants such as H2O2 and HOCl. The changes in pyrene monomer fluorescence to excimer were used in the quantitative analysis of PAA. When using the surfactant hexadecyltrimethylammonium bromide as a micellar additive, the signaling of PAA was markedly enhanced. Selective fluorescence signaling of PAA by pyrene-1-boronic acid with a detection limit of 1.5×10(-6)M in aqueous environment was successfully achieved. Copyright © 2015 Elsevier B.V. All rights reserved.

Driver Circuit For High-Power MOSFET's

Science.gov (United States)

Letzer, Kevin A.

1991-01-01

Driver circuit generates rapid-voltage-transition pulses needed to switch high-power metal oxide/semiconductor field-effect transistor (MOSFET) modules rapidly between full "on" and full "off". Rapid switching reduces time of overlap between appreciable current through and appreciable voltage across such modules, thereby increasing power efficiency.

High power industrial picosecond laser from IR to UV

Science.gov (United States)

Saby, Julien; Sangla, Damien; Pierrot, Simonette; Deslandes, Pierre; Salin, François

2013-02-01

Many industrial applications such as glass cutting, ceramic micro-machining or photovoltaic processes require high average and high peak power Picosecond pulses. The main limitation for the expansion of the picosecond market is the cost of high power picosecond laser sources, which is due to the complexity of the architecture used for picosecond pulse amplification, and the difficulty to keep an excellent beam quality at high average power. Amplification with fibers is a good technology to achieve high power in picosecond regime but, because of its tight confinement over long distances, light undergoes dramatic non linearities while propagating in fibers. One way to avoid strong non linearities is to increase fiber's mode area. Nineteen missing holes fibers offering core diameter larger than 80μm have been used over the past few years [1-3] but it has been shown that mode instabilities occur at approximately 100W average output power in these fibers [4]. Recently a new fiber design has been introduced, in which HOMs are delocalized from the core to the clad, preventing from HOMs amplification [5]. In these so-called Large Pitch Fibers, threshold for mode instabilities is increased to 294W offering robust single-mode operation below this power level [6]. We have demonstrated a high power-high efficiency industrial picosecond source using single-mode Large Pitch rod-type fibers doped with Ytterbium. Large Pitch Rod type fibers can offer a unique combination of single-mode output with a very large mode area from 40 μm up to 100μm and very high gain. This enables to directly amplify a low power-low energy Mode Locked Fiber laser with a simple amplification architecture, achieving very high power together with singlemode output independent of power level or repetition rate.

High power neutral beam injection in LHD

International Nuclear Information System (INIS)

Tsumori, K.; Takeiri, Y.; Nagaoka, K.

2005-01-01

The results of high power injection with a neutral beam injection (NBI) system for the large helical device (LHD) are reported. The system consists of three beam-lines, and two hydrogen negative ion (H - ion) sources are installed in each beam-line. In order to improve the injection power, the new beam accelerator with multi-slot grounded grid (MSGG) has been developed and applied to one of the beam-lines. Using the accelerator, the maximum powers of 5.7 MW were achieved in 2003 and 2004, and the energy of 189 keV reached at maximum. The power and energy exceeded the design values of the individual beam-line for LHD. The other beam-lines also increased their injection power up to about 4 MW, and the total injection power of 13.1 MW was achieved with three beam-lines in 2003. Although the accelerator had an advantage in high power beam injection, it involved a demerit in the beam focal condition. The disadvantage was resolved by modifying the aperture shapes of the steering grid. (author)

High-power microwave diplexers for advanced ECRH systems

International Nuclear Information System (INIS)

Kasparek, W.; Petelin, M.; Erckmann, V.; Bruschi, A.; Noke, F.; Purps, F.; Hollmann, F.; Koshurinov, Y.; Lubyako, L.; Plaum, B.; Wubie, W.

2009-01-01

In electron cyclotron resonance heating systems, high-power multiplexers can be employed as power combiners, adjustable power dividers, fast switches to toggle the power between two launchers, as well as frequency sensitive directional couplers to combine heating and diagnostic applications on one launcher. In the paper, various diplexer designs for quasi-optical and corrugated waveguide transmission systems are discussed. Numerical calculations, low-power tests and especially high-power experiments performed at the ECRH system of W7-X are shown, which demonstrate the capability of these devices. Near term plans for applications on ASDEX Upgrade and FTU are presented. Based on the present results, options for implementation of power combiners and fast switches in the ECRH system of ITER is discussed.

Effect of excimer laser annealing on a-InGaZnO thin-film transistors passivated by solution-processed hybrid passivation layers

Science.gov (United States)

Bermundo, Juan Paolo; Ishikawa, Yasuaki; Fujii, Mami N.; Nonaka, Toshiaki; Ishihara, Ryoichi; Ikenoue, Hiroshi; Uraoka, Yukiharu

2016-01-01

We demonstrate the use of excimer laser annealing (ELA) as a low temperature annealing alternative to anneal amorphous InGaZnO (a-IGZO) thin-film transistors (TFTs) passivated by a solution-processed hybrid passivation layer. Usually, a-IGZO is annealed using thermal annealing at high temperatures of up to 400 °C. As an alternative to high temperature thermal annealing, two types of ELA, XeCl (308 nm) and KrF (248 nm) ELA, are introduced. Both ELA types enhanced the electrical characteristics of a-IGZO TFTs leading to a mobility improvement of ~13 cm2 V-1 s-1 and small threshold voltage which varied from ~0-3 V. Furthermore, two-dimensional heat simulation using COMSOL Multiphysics was used to identify possible degradation sites, analyse laser heat localization, and confirm that the substrate temperature is below 50 °C. The two-dimensional heat simulation showed that the substrate temperature remained at very low temperatures, less than 30 °C, during ELA. This implies that any flexible material can be used as the substrate. These results demonstrate the large potential of ELA as a low temperature annealing alternative for already-passivated a-IGZO TFTs.

High-power fiber-coupled pump lasers for fiber lasers

Science.gov (United States)

Kasai, Yohei; Aizawa, Takuya; Tanaka, Daiichiro

2018-02-01

We present high-power fiber-coupled pump modules utilized effectively for ultra-high power single-mode (SM) fiber lasers. Maximum output power of 392 W was achieved at 23 A for 915 nm pump, and 394 W for 976 nm pump. Fiber core diameter is 118 μm and case temperature is 25deg. C. Polarization multiplexing technique was newly applied to our optical system. High-reliability of the laser diodes (LD) at high-power operation has been demonstrated by aging tests. Advanced package structure was developed that manages uncoupled light around input end of the fiber. 800 hours continuous drive with uncoupled light power of 100 W has been achieved.

Excimer laser sintering of indium tin oxide nanoparticles for fabricating thin films of variable thickness on flexible substrates

International Nuclear Information System (INIS)

Park, Taesoon; Kim, Dongsik

2015-01-01

Technology to fabricate electrically-conducting, transparent thin-film patterns on flexible substrates has possible applications in flexible electronics. In this work, a pulsed-laser sintering process applicable to indium tin oxide (ITO) thin-film fabrication on a substrate without thermal damage to the substrate was developed. A nanosecond pulsed laser was used to minimize thermal penetration into the substrate and to control the thickness of the sintered layer. ITO nanoparticles (NPs) of ~ 20 nm diameter were used to lower the process temperature by exploiting their low melting point. ITO thin film patterns were fabricated by first spin coating the NPs onto a surface, then sintering them using a KrF excimer laser. The sintered films were characterized using field emission scanning electron microscopy. The electrical resistivity and transparency of the film were measured by varying the process parameters. A single laser pulse could generate the polycrystalline structure (average grain size ~ 200 nm), reducing the electrical resistivity of the film by a factor of ~ 1000. The sintering process led to a minimum resistivity of 1.1 × 10 −4 Ω·m without losing the transparency of the film. The thickness of the sintered layer could be varied up to 150 nm by adjusting the laser fluence. Because the estimated thermal penetration depth in the ITO film was less than 200 nm, no thermal damage was observed in the substrate. This work suggests that the proposed process, combined with various particle deposition methods, can be an effective tool to form thin-film ITO patterns on flexible substrates. - Highlights: • Excimer laser sintering can fabricate ITO thin films on flexible substrates. • The laser pulse can form a polycrystalline structure without thermal damage. • The laser sintering process can reduce the electrical resistivity substantially. • The thickness of the sintered layer can be varied effectively

Excimer laser sintering of indium tin oxide nanoparticles for fabricating thin films of variable thickness on flexible substrates

Energy Technology Data Exchange (ETDEWEB)

Park, Taesoon; Kim, Dongsik, E-mail: dskim87@postech.ac.kr

2015-03-02

Technology to fabricate electrically-conducting, transparent thin-film patterns on flexible substrates has possible applications in flexible electronics. In this work, a pulsed-laser sintering process applicable to indium tin oxide (ITO) thin-film fabrication on a substrate without thermal damage to the substrate was developed. A nanosecond pulsed laser was used to minimize thermal penetration into the substrate and to control the thickness of the sintered layer. ITO nanoparticles (NPs) of ~ 20 nm diameter were used to lower the process temperature by exploiting their low melting point. ITO thin film patterns were fabricated by first spin coating the NPs onto a surface, then sintering them using a KrF excimer laser. The sintered films were characterized using field emission scanning electron microscopy. The electrical resistivity and transparency of the film were measured by varying the process parameters. A single laser pulse could generate the polycrystalline structure (average grain size ~ 200 nm), reducing the electrical resistivity of the film by a factor of ~ 1000. The sintering process led to a minimum resistivity of 1.1 × 10{sup −4} Ω·m without losing the transparency of the film. The thickness of the sintered layer could be varied up to 150 nm by adjusting the laser fluence. Because the estimated thermal penetration depth in the ITO film was less than 200 nm, no thermal damage was observed in the substrate. This work suggests that the proposed process, combined with various particle deposition methods, can be an effective tool to form thin-film ITO patterns on flexible substrates. - Highlights: • Excimer laser sintering can fabricate ITO thin films on flexible substrates. • The laser pulse can form a polycrystalline structure without thermal damage. • The laser sintering process can reduce the electrical resistivity substantially. • The thickness of the sintered layer can be varied effectively.

A high pulsed power supply system designed for pulsed high magnetic field

International Nuclear Information System (INIS)

Liu Kefu; Wang Shaorong; Zhong Heqing; Xu Yan; Pan Yuan

2008-01-01

This paper introduces the design of high pulsed power supply system for producing pulsed high magnetic field up to 70 T. This system consists of 58 sets of 55 μF of capacitor bank which provides 1.0 MJ energy storage. A set of vacuum closing switch is chosen as main switch for energy discharge into magnetic coil. A crowbar circuit with high power diodes in series with resistor is used to absorb the redundant energy and adjust pulse width. The resistance of magnetic coil changing with current is deduced by energy balance equations. A capacitor-charging power supply using a series-resonant, constant on-time variable frequency control, and zero-current switching charges the capacitor bank in one minute time with high efficiency. The pulsed power supply provides adjustable current and pulse width with 30 kA peak and 30 ms maximum. The primary experiments demonstrate the system reliability. This work provides an engineering guidance for future development of pulsed high magnetic field. (authors)

High-power laser diodes with high polarization purity

Science.gov (United States)

Rosenkrantz, Etai; Yanson, Dan; Peleg, Ophir; Blonder, Moshe; Rappaport, Noam; Klumel, Genady

2017-02-01

Fiber-coupled laser diode modules employ power scaling of single emitters for fiber laser pumping. To this end, techniques such as geometrical, spectral and polarization beam combining (PBC) are used. For PBC, linear polarization with high degree of purity is important, as any non-perfectly polarized light leads to losses and heating. Furthermore, PBC is typically performed in a collimated portion of the beams, which also cancels the angular dependence of the PBC element, e.g., beam-splitter. However, we discovered that single emitters have variable degrees of polarization, which depends both on the operating current and far-field divergence. We present data to show angle-resolved polarization measurements that correlate with the ignition of high-order modes in the slow-axis emission of the emitter. We demonstrate that the ultimate laser brightness includes not only the standard parameters such as power, emitting area and beam divergence, but also the degree of polarization (DoP), which is a strong function of the latter. Improved slow-axis divergence, therefore, contributes not only to high brightness but also high beam combining efficiency through polarization.

High-power VCSELs for smart munitions

Science.gov (United States)

Geske, Jon; MacDougal, Michael; Cole, Garrett; Snyder, Donald

2006-08-01

The next generation of low-cost smart munitions will be capable of autonomously detecting and identifying targets aided partly by the ability to image targets with compact and robust scanning rangefinder and LADAR capabilities. These imaging systems will utilize arrays of high performance, low-cost semiconductor diode lasers capable of achieving high peak powers in pulses ranging from 5 to 25 nanoseconds in duration. Aerius Photonics is developing high-power Vertical-Cavity Surface-Emitting Lasers (VCSELs) to meet the needs of these smart munitions applications. The authors will report the results of Aerius' development program in which peak pulsed powers exceeding 60 Watts were demonstrated from single VCSEL emitters. These compact packaged emitters achieved pulse energies in excess of 1.5 micro-joules with multi kilo-hertz pulse repetition frequencies. The progress of the ongoing effort toward extending this performance to arrays of VCSEL emitters and toward further improving laser slope efficiency will be reported.

Flexible asymmetric supercapacitors with high energy and high power density in aqueous electrolytes

Science.gov (United States)

Cheng, Yingwen; Zhang, Hongbo; Lu, Songtao; Varanasi, Chakrapani V.; Liu, Jie

2013-01-01

Supercapacitors with both high energy and high power densities are critical for many practical applications. In this paper, we discuss the design and demonstrate the fabrication of flexible asymmetric supercapacitors based on nanocomposite electrodes of MnO2, activated carbon, carbon nanotubes and graphene. The combined unique properties of each of these components enable highly flexible and mechanically strong films that can serve as electrodes directly without using any current collectors or binders. Using these flexible electrodes and a roll-up approach, asymmetric supercapacitors with 2 V working voltage were successfully fabricated. The fabricated device showed excellent rate capability, with 78% of the original capacitance retained when the scan rate was increased from 2 mV s-1 to 500 mV s-1. Owing to the unique composite structure, these supercapacitors were able to deliver high energy density (24 W h kg-1) under high power density (7.8 kW kg-1) conditions. These features could enable supercapacitor based energy storage systems to be very attractive for a variety of critical applications, such as the power sources in hybrid electric vehicles and the back-up powers for wind and solar energy, where both high energy density and high power density are required.Supercapacitors with both high energy and high power densities are critical for many practical applications. In this paper, we discuss the design and demonstrate the fabrication of flexible asymmetric supercapacitors based on nanocomposite electrodes of MnO2, activated carbon, carbon nanotubes and graphene. The combined unique properties of each of these components enable highly flexible and mechanically strong films that can serve as electrodes directly without using any current collectors or binders. Using these flexible electrodes and a roll-up approach, asymmetric supercapacitors with 2 V working voltage were successfully fabricated. The fabricated device showed excellent rate capability, with 78% of

Post-growth annealing of germanium-tin alloys using pulsed excimer laser

Energy Technology Data Exchange (ETDEWEB)

Wang, Lanxiang; Wang, Wei; Zhou, Qian; Yeo, Yee-Chia, E-mail: yeo@ieee.org [Department of Electrical and Computer Engineering, National University of Singapore, Singapore 117582 (Singapore); Pan, Jisheng; Zhang, Zheng [Institute of Materials Research and Engineering, A*STAR (Agency for Science, Technology and Research), Singapore 117602 (Singapore); Tok, Eng Soon [Department of Physics, National University of Singapore, Singapore 117551 (Singapore)

2015-07-14

We investigate the impact of pulsed excimer laser anneal on fully strained germanium-tin alloys (Ge{sub 1−x}Sn{sub x}) epitaxially grown on Ge substrate by molecular beam epitaxy. Using atomic force microscopy, X-ray diffraction, transmission electron microscopy, and X-ray photoelectron spectroscopy, the morphological and compositional evolution of Ge{sub 1−x}Sn{sub x} with Sn content up to 17% after annealing using various conditions is studied. Ge{sub 0.83}Sn{sub 0.17} samples annealed at 80 mJ/cm{sup 2} or 150 mJ/cm{sup 2} have no observable changes with respect to the as-grown sample. However, Ge{sub 0.83}Sn{sub 0.17} samples annealed at 250 mJ/cm{sup 2} or 300 mJ/cm{sup 2} have Sn-rich islands on the surface, which is due to Sn segregation in the compressively strained epitaxial film. For Ge{sub 0.89}Sn{sub 0.11}, significant Sn redistribution occurs only when annealed at 300 mJ/cm{sup 2}, indicating that it has better thermal stability than Ge{sub 0.83}Sn{sub 0.17}. A mechanism is proposed to explain the formation of Sn-rich islands and Sn-depleted regions.

Design of 120 MW beam power electron gun for high power klystron

International Nuclear Information System (INIS)

Zhou Zusheng; Dong Dong

2005-01-01

An electron gun was designed and the beam optics for a China-made 50 MW klystron was simulated. The electron gun ceramic cylinder was designed and optimized. The China-made cathode was replaced with an imported one to lessen evaporation and arcing. The high voltage (320 kV) of the cathode was increased to meet the klystron output power demand and a low electric field strength (22.1 kV/mm) electron gun was designed to avoid the high power operation which damaged the ceramic cylinder. The klystron output power was increased and life span extended. (authors)

Los Alamos high-power proton linac designs

Energy Technology Data Exchange (ETDEWEB)

Lawrence, G.P. [Los Alamos National Laboratory, NM (United States)

1995-10-01

Medium-energy high-power proton linear accelerators have been studied at Los Alamos as drivers for spallation neutron applications requiring large amounts of beam power. Reference designs for such accelerators are discussed, important design factors are reviewed, and issues and concern specific to this unprecedented power regime are discussed.

High power laser exciter accelerators

International Nuclear Information System (INIS)

Martin, T.H.

1975-01-01

Recent developments in untriggered oil and water switching now permit the construction of compact, high energy density pulsed power sources for laser excitation. These accelerators, developed principally for electron beam fusion studies, appear adaptable to laser excitation and will provide electron beams of 10 13 to 10 14 W in the next several years. The accelerators proposed for e-beam fusion essentially concentrate the available power from the outside edge of a disk into the central region where the electron beam is formed. One of the main problem areas, that of power flow at the vacuum diode insulator, is greatly alleviated by the multiplicity of electron beams that are allowable for laser excitation. A proposal is made whereby the disk-shaped pulsed power sections are stacked vertically to form a series of radially flowing electron beams to excite the laser gas volume. (auth)

Design and development of high voltage high power operational ...

Indian Academy of Sciences (India)

address this challenge, a) Designing a discrete power opamp with high .... the use of high-impedance feedback networks, thus minimizing their output loading ... Spice simulation is done for the circuit and results are given in figures 4a–c.

The NASA CSTI High Capacity Power Program

International Nuclear Information System (INIS)

Winter, J.M.

1991-09-01

The SP-100 program was established in 1983 by DOD, DOE, and NASA as a joint program to develop the technology necessary for space nuclear power systems for military and civil applications. During 1986 and 1987, the NASA Advanced Technology Program was responsible for maintaining the momentum of promising technology advancement efforts started during Phase 1 of SP-100 and to strengthen, in key areas, the chances for successful development and growth capability of space nuclear reactor power systems for future space applications. In 1988, the NASA Advanced Technology Program was incorporated into NASA's new Civil Space Technology Initiative (CSTI). The CSTI program was established to provide the foundation for technology development in automation and robotics, information, propulsion, and power. The CSTI High Capacity Power Program builds on the technology efforts of the SP-100 program, incorporates the previous NASA advanced technology project, and provides a bridge to the NASA exploration technology programs. The elements of CSTI high capacity power development include conversion systems: Stirling and thermoelectric, thermal management, power management, system diagnostics, and environmental interactions. Technology advancement in all areas, including materials, is required to provide the growth capability, high reliability, and 7 to 10 year lifetime demanded for future space nuclear power systems. The overall program will develop and demonstrate the technology base required to provide a wide range of modular power systems while minimizing the impact of day/night operations as well as attitudes and distance from the Sun. Significant accomplishments in all of the program elements will be discussed, along with revised goals and project timelines recently developed

High-power semiconductor RSD-based switch

Energy Technology Data Exchange (ETDEWEB)

Bezuglov, V G; Galakhov, I V; Grusin, I A [All-Russian Scientific Research Inst. of Experimental Physics, Sarov (Russian Federation); and others

1997-12-31

The operating principle and test results of a high-power semiconductor RSD-based switch with the following operating parameters is described: operating voltage 25 kV, peak operating current 200 kA, maximum transferred charge 70 C. The switch is intended for use by high-power capacitor banks of state-of-the-art research facilities. The switch was evaluated for applicability in commercial pulsed systems. The possibility of increasing the peak operating current to 500 kA is demonstrated. (author). 4 figs., 2 refs.

Analyses of surface coloration on TiO2 film irradiated with excimer laser

International Nuclear Information System (INIS)

Zheng, H.Y.; Qian, H.X.; Zhou, W.

2008-01-01

TiO 2 film of around 850 nm in thickness was deposited on a soda-lime glass by PVD sputtering and irradiated using one pulse of krypton-fluorine (KrF) excimer laser (wavelength of 248 nm and pulse duration of 25 ns) with varying fluence. The color of the irradiated area became darker with increasing laser fluence. Irradiated surfaces were characterized using optical microscopy, scanning electron microscopy, Raman spectroscopy and atomic force microscopy. Surface undergoes thermal annealing at low laser fluence of 400 and 590 mJ/cm 2 . Microcracks at medium laser fluence of 1000 mJ/cm 2 are attributed to surface melting and solidification. Hydrodynamic ablation is proposed to explain the formation of micropores and networks at higher laser fluence of 1100 and 1200 mJ/cm 2 . The darkening effect is explained in terms of trapping of light in the surface defects formed rather than anatase to rutile phase transformation as reported by others. Controlled darkening of TiO 2 film might be used for adjustable filters

High efficiency and stable white OLED using a single emitter

Energy Technology Data Exchange (ETDEWEB)

Li, Jian [Arizona State Univ., Tempe, AZ (United States). School of Mechanical, Aerospace, Chemical and Materials Engineering

2016-01-18

The ultimate objective of this project was to demonstrate an efficient and stable white OLED using a single emitter on a planar glass substrate. The focus of the project is on the development of efficient and stable square planar phosphorescent emitters and evaluation of such class of materials in the device settings. Key challenges included improving the emission efficiency of molecular dopants and excimers, controlling emission color of emitters and their excimers, and improving optical and electrical stability of emissive dopants. At the end of this research program, the PI has made enough progress to demonstrate the potential of excimer-based white OLED as a cost-effective solution for WOLED panel in the solid state lighting applications.

DNA damage in cultured human skin fibroblasts exposed to excimer laser radiation

Energy Technology Data Exchange (ETDEWEB)

Rimoldi, D.; Miller, A.C.; Freeman, S.E.; Samid, D. (Department of Pathology, Uniformed Services University of the Health Sciences, Bethesda, MD (USA))

1991-06-01

Ultraviolet excimer lasers are being considered for use in a variety of refractive and therapeutic procedures, the long-term biologic consequences of which are unknown. The effect of sublethal doses of 193-nm laser radiation on cellular DNA was examined in cultured human skin fibroblasts. In contrast to 248 nm, treatments with the 193-nm laser radiation below 70 J/m2 did not cause significant pyrimidine dimer formation in the skin cells. This was indicated by the lack of excision repair activities (unscheduled DNA synthesis assay), and further demonstrated by direct analysis of pyrimidine dimers in DNA from irradiated cells. However, a low level of unscheduled DNA synthesis could be detected following irradiation at 193 nm with 70 J/m2. Both the 193-nm and 248-nm radiation were able to induce chromosomal aberrations, as indicated by a micronucleus assay. A dose-dependent increase in micronuclei frequency was observed 48 and 72 h after laser irradiation. These results indicate that exposure of actively replicating human skin fibroblasts to sublethal doses of either 193- or 248-nm laser radiation can result in genotoxicity.

Insight into excimer laser crystallization exploiting ellipsometry: Effect of silicon film precursor

Energy Technology Data Exchange (ETDEWEB)

Losurdo, Maria [Institute of Inorganic Methodologies and of Plasmas, IMIP-CNR and INSTM sez. Bari, Via Orabona 4, 70125 Bari (Italy)], E-mail: maria.losurdo@ba.imip.cnr.it; Giangregorio, Maria M.; Sacchetti, Alberto; Capezzuto, Pio; Bruno, Giovanni [Institute of Inorganic Methodologies and of Plasmas, IMIP-CNR and INSTM sez. Bari, Via Orabona 4, 70125 Bari (Italy); Mariucci, Luigi; Fortunato, Guglielmo [IFN-CNR, Via Cineto Romano, 42 - 00156 Rome (Italy)

2007-07-16

The optical diagnostic of spectroscopic ellipsometry is shown to be an effective tool to investigate the mechanism of excimer laser crystallization (ELC) of silicon thin films. A detailed spectroscopic ellipsometric investigation of the microstructures of polycrystalline Si films obtained on SiO{sub 2}/Si wafers by ELC of a-Si:H and nc-Si films deposited, respectively, by SiH{sub 4} plasma enhanced chemical vapor deposition (PECVD) and SiF{sub 4}-PECVD is presented. It is shown that ellipsometric spectra of the pseudodielectric function of polysilicon thin films allows to discern the three different ELC regimes of partial melting, super lateral growth and complete melting. Exploiting ellipsometry and atomic force microscopy, it is shown that ELC of nc-Si has very low energy density threshold of 95 mJ/cm{sup 2} for complete melting, and that re-crystallization to large grains of {approx} 2 {mu}m can be achieved by multi-shot irradiation at an energy density as low as 260 mJ/cm{sup 2} when using nc-Si when compared to 340 mJ/cm{sup 2} for the ELC of a-Si films.

Experiments on high power EB evaporation of niobium

International Nuclear Information System (INIS)

Kandaswamy, E.; Bhardwaj, R.L.; Ram Gopal; Ray, A.K.; Kulgod, S.V.

2002-01-01

Full text: The versatility of electron beam evaporation makes the deposition of many new and unusual materials possible. This technique offers freedom from contamination and precise control. High power electron guns are especially used for obtaining high evaporation rates for large area coatings. This paper deals with the coating experiments carried out on an indigenously developed high power strip electron gun with niobium as evaporant at 40 kW on S.S. substrate. The practical problems of conditioning the gun and venting the vacuum system after the high power operation are also discussed. The coating rate was calculated by weight difference method

High-efficency stable 213-nm generation for LASIK application

Science.gov (United States)

Wang, Zhenglin; Alameh, Kamal; Zheng, Rong

2005-01-01

213nm Solid-state laser technology provides an alternative method to replace toxic excimer laser in LASIK system. In this paper, we report a compact fifth harmonic generation system to generate high pulse energy 213nm laser from Q-switched Nd:YAG laser for LASIK application based on three stages harmonic generation procedures. A novel crystal housing was specifically designed to hold the three crystals with each crystal has independent, precise angular adjustment structure and automatic tuning control. The crystal temperature is well maintained at ~130°C to improve harmonic generation stability and crystal operation lifetime. An output pulse energy 35mJ is obtained at 213nm, corresponding to total conversion efficiency ~10% from 1064nm pump laser. In system verification tests, the 213nm output power drops less than 5% after 5 millions pulse shots and no significant damage appears in the crystals.

High-power pre-chirp managed amplification of femtosecond pulses at high repetition rates

International Nuclear Information System (INIS)

Liu, Yang; Li, Wenxue; Zhao, Jian; Bai, Dongbi; Luo, Daping; Zeng, Heping

2015-01-01

Femtosecond pulses at 250 MHz repetition rate from a mode-locked fiber laser are amplified to high power in a pre-chirp managed amplifier. The experimental strategy offers a potential towards high-power ultrashort laser pulses at high repetition rates. By investigating the laser pulse evolution in the amplification processes, we show that self-similar evolution, finite gain bandwidth and mode instabilities determine pulse characteristics in different regimes. Further average power scaling is limited by the mode instabilities. Nevertheless, this laser system enables us to achieve sub-50 fs pulses with an average power of 93 W. (letter)

ACIGA's high optical power test facility

International Nuclear Information System (INIS)

Ju, L; Aoun, M; Barriga, P

2004-01-01

Advanced laser interferometer detectors utilizing more than 100 W of laser power and with ∼10 6 W circulating laser power present many technological problems. The Australian Consortium for Interferometric Gravitational Astronomy (ACIGA) is developing a high power research facility in Gingin, north of Perth, Western Australia, which will test techniques for the next generation interferometers. In particular it will test thermal lensing compensation and control strategies for optical cavities in which optical spring effects and parametric instabilities may present major difficulties

High power all solid state VUV lasers

International Nuclear Information System (INIS)

Zhang, Shen-jin; Cui, Da-fu; Zhang, Feng-feng; Xu, Zhi; Wang, Zhi-min; Yang, Feng; Zong, Nan; Tu, Wei; Chen, Ying; Xu, Hong-yan; Xu, Feng-liang; Peng, Qin-jun; Wang, Xiao-yang; Chen, Chuang-tian; Xu, Zu-yan

2014-01-01

Highlights: • Polarization and pulse repetition rate adjustable ps 177.3 nm laser was developed. • Wavelength tunable ns, ps and fs VUV lasers were developed. • High power ns 177.3 nm laser with narrow linewidth was investigated. - Abstract: We report the investigation on the high power all solid state vacuum ultra-violet (VUV) lasers by means of nonlinear frequency conversion with KBe 2 BO 3 F 2 (KBBF) nonlinear crystal. Several all solid state VUV lasers have developed in our group, including polarization and pulse repetition rate adjustable picosecond 177.3 nm VUV laser, wavelength tunable nanosecond, picosecond and femtosecond VUV lasers, high power ns 177.3 nm laser with narrow linewidth. The VUV lasers have impact, accurate and precise advantage

Compact high-power terahertz radiation source

Directory of Open Access Journals (Sweden)

G. A. Krafft

2004-06-01

Full Text Available In this paper a new type of THz radiation source, based on recirculating an electron beam through a high gradient superconducting radio frequency cavity, and using this beam to drive a standard electromagnetic undulator on the return leg, is discussed. Because the beam is recirculated and not stored, short bunches may be produced that radiate coherently in the undulator, yielding exceptionally high average THz power for relatively low average beam power. Deceleration from the coherent emission, and the detuning it causes, limits the charge-per-bunch possible in such a device.

High Energy Density Sciences with High Power Lasers at SACLA

Science.gov (United States)

Kodama, Ryosuke

2013-10-01

One of the interesting topics on high energy density sciences with high power lasers is creation of extremely high pressures in material. The pressures of more than 0.1 TPa are the energy density corresponding to the chemical bonding energy, resulting in expectation of dramatic changes in the chemical reactions. At pressures of more than TPa, most of material would be melted on the shock Hugoniot curve. However, if the temperature is less than 1eV or lower than a melting point at pressures of more than TPa, novel solid states of matter must be created through a pressured phase transition. One of the interesting materials must be carbon. At pressures of more than TPa, the diamond structure changes to BC and cubic at more than 3TPa. To create such novel states of matter, several kinds of isentropic-like compression techniques are being developed with high power lasers. To explore the ``Tera-Pascal Science,'' now we have a new tool which is an x-ray free electron laser as well as high power lasers. The XFEL will clear the details of the HED states and also efficiently create hot dense matter. We have started a new project on high energy density sciences using an XFEL (SACLA) in Japan, which is a HERMES (High Energy density Revolution of Matter in Extreme States) project.

Predicting High-Power Performance in Professional Cyclists.

Science.gov (United States)

Sanders, Dajo; Heijboer, Mathieu; Akubat, Ibrahim; Meijer, Kenneth; Hesselink, Matthijs K

2017-03-01

To assess if short-duration (5 to ~300 s) high-power performance can accurately be predicted using the anaerobic power reserve (APR) model in professional cyclists. Data from 4 professional cyclists from a World Tour cycling team were used. Using the maximal aerobic power, sprint peak power output, and an exponential constant describing the decrement in power over time, a power-duration relationship was established for each participant. To test the predictive accuracy of the model, several all-out field trials of different durations were performed by each cyclist. The power output achieved during the all-out trials was compared with the predicted power output by the APR model. The power output predicted by the model showed very large to nearly perfect correlations to the actual power output obtained during the all-out trials for each cyclist (r = .88 ± .21, .92 ± .17, .95 ± .13, and .97 ± .09). Power output during the all-out trials remained within an average of 6.6% (53 W) of the predicted power output by the model. This preliminary pilot study presents 4 case studies on the applicability of the APR model in professional cyclists using a field-based approach. The decrement in all-out performance during high-intensity exercise seems to conform to a general relationship with a single exponential-decay model describing the decrement in power vs increasing duration. These results are in line with previous studies using the APR model to predict performance during brief all-out trials. Future research should evaluate the APR model with a larger sample size of elite cyclists.

Inverter design for high frequency power distribution

Science.gov (United States)

King, R. J.

1985-01-01

A class of simple resonantly commutated inverters are investigated for use in a high power (100 KW - 1000 KW) high frequency (10 KHz - 20 KHz) AC power distribution system. The Mapham inverter is found to provide a unique combination of large thyristor turn-off angle and good utilization factor, much better than an alternate 'current-fed' inverter. The effects of loading the Mapham inverter entirely with rectifier loads are investigated by simulation and with an experimental 3 KW 20 KHz inverter. This inverter is found to be well suited to a power system with heavy rectifier loading.

Reducing AC-Winding Losses in High-Current High-Power Inductors

DEFF Research Database (Denmark)

Nymand, Morten; Madawala, Udaya K.; Andersen, Michael Andreas E.

2009-01-01

Foil windings are preferable in high-current high-power inductors to realize compact designs and to reduce dc-current losses. At high frequency, however, proximity effect will cause very significant increase in ac resistance in multi-layer windings, and lead to high ac winding losses. This paper ...

Economic Justification of Concentrating Solar Power in High Renewable Energy Penetrated Power Systems

Energy Technology Data Exchange (ETDEWEB)

Hodge, Brian S [National Renewable Energy Laboratory (NREL), Golden, CO (United States); Kroposki, Benjamin D [National Renewable Energy Laboratory (NREL), Golden, CO (United States); Du, Ershun [Tsinghua University; Zhang, Ning [Tsinghua University; Kang, Chongqing [Tsinghua University; Xia, Qing [Tsinghua University

2018-04-24

Concentrating solar power (CSP) plants are able to provide both renewable energy and operational flexibility at the same time due to its thermal energy storage (TES). It is ideal generation to power systems lacking in flexibility to accommodate variable renewable energy (VRE) generation such as wind power and photovoltaics. However, its investment cost currently is too high to justify its benefit in terms of providing renewable energy only. In this paper we evaluate the economic benefit of CSP in high renewable energy penetrated power systems from two aspects: generating renewable energy and providing operational flexibility to help accommodating VRE. In order to keep the same renewable energy penetration level during evaluation, we compare the economic costs between the system with a high share of VRE and another in which some part of the VRE generation is replaced by CSP generation. The generation cost of a power system is analyzed through chronological operation simulation over a whole year. The benefit of CSP is quantified into two parts: (1) energy benefit - the saving investment of substituted VRE generation and (2) flexibility benefit - the reduction in operating cost due to substituting VRE with CSP. The break-even investment cost of CSP is further discussed. The methodology is tested on a modified IEEE RTS-79 system. The economic justifications of CSP are demonstrated in two practical provincial power systems with high penetration of renewable energy in northwestern China, Qinghai and Gansu, where the former province has massive inflexible thermal power plants but later one has high share of flexible hydro power. The results suggest that the CSP is more beneficial in Gansu system than in Qinghai. The levelized benefit of CSP, including both energy benefit and flexibility benefit, is about 0.177-0.191 $/kWh in Qinghai and about 0.238-0.300 $/kWh in Gansu, when replacing 5-20% VRE generation with CSP generation.

Silicon-Carbide Power MOSFET Performance in High Efficiency Boost Power Processing Unit for Extreme Environments

Science.gov (United States)

Ikpe, Stanley A.; Lauenstein, Jean-Marie; Carr, Gregory A.; Hunter, Don; Ludwig, Lawrence L.; Wood, William; Del Castillo, Linda Y.; Fitzpatrick, Fred; Chen, Yuan

2016-01-01

Silicon-Carbide device technology has generated much interest in recent years. With superior thermal performance, power ratings and potential switching frequencies over its Silicon counterpart, Silicon-Carbide offers a greater possibility for high powered switching applications in extreme environment. In particular, Silicon-Carbide Metal-Oxide- Semiconductor Field-Effect Transistors' (MOSFETs) maturing process technology has produced a plethora of commercially available power dense, low on-state resistance devices capable of switching at high frequencies. A novel hard-switched power processing unit (PPU) is implemented utilizing Silicon-Carbide power devices. Accelerated life data is captured and assessed in conjunction with a damage accumulation model of gate oxide and drain-source junction lifetime to evaluate potential system performance at high temperature environments.

Optimizing the design of very high power, high performance converters

International Nuclear Information System (INIS)

Edwards, R.J.; Tiagha, E.A.; Ganetis, G.; Nawrocky, R.J.

1980-01-01

This paper describes how various technologies are used to achieve the desired performance in a high current magnet power converter system. It is hoped that the discussions of the design approaches taken will be applicable to other power supply systems where stringent requirements in stability, accuracy and reliability must be met

High power density carbonate fuel cell

Energy Technology Data Exchange (ETDEWEB)

Yuh, C.; Johnsen, R.; Doyon, J.; Allen, J. [Energy Research Corp., Danbury, CT (United States)

1996-12-31

Carbonate fuel cell is a highly efficient and environmentally clean source of power generation. Many organizations worldwide are actively pursuing the development of the technology. Field demonstration of multi-MW size power plant has been initiated in 1996, a step toward commercialization before the turn of the century, Energy Research Corporation (ERC) is planning to introduce a 2.85MW commercial fuel cell power plant with an efficiency of 58%, which is quite attractive for distributed power generation. However, to further expand competitive edge over alternative systems and to achieve wider market penetration, ERC is exploring advanced carbonate fuel cells having significantly higher power densities. A more compact power plant would also stimulate interest in new markets such as ships and submarines where space limitations exist. The activities focused on reducing cell polarization and internal resistance as well as on advanced thin cell components.

Study into the applicabilities of lasers for the dismantling of decommissioned nuclear power plant

International Nuclear Information System (INIS)

Haferkamp, H.; Bach, F.W.; Vinke, T.; Kinzel, A.; Mack, N.; Kuboschek, M.; Grobe, K.

1989-01-01

The project was intended to screen current laser technology for potential applications of laser beams in the dismantling of decommissioned nuclear power plant. As with CO 2 , Nd-YAG, or excimer lasers, developments clearly proceed towards higher output power. The market survey shows the CO 2 -laser to be the most efficient at present, with a great number of laser units available on the market in the range up to 5 kW, and some in the range up to 15 kW. The CO 2 -laser has exclusively been used so far for cutting work in steel plates thicker than 10 mm. Characteristic conditions of application include the high output power of more than 2 kW, long beam lengths, oxygen supply at strongly increased working pressure, sometimes from external sources. The maximum cutting work achieved in the laboratory was 110 mm in structural steel, 90 mm in austenitic steel, and 160 mm in concrete, all under conditions of easy access to the material. It remains to be examined whether steel cutting work at constrained positions will allow separation of wall thicknesses of more than 10 mm. Laser beam cutting under water is feasible in principle but has not been much studied yet. There also are only few sampling results of measurements of dust and aerosol quantities resulting from laser beam cutting work. (orig.) [de

Compact high voltage, high peak power, high frequency transformer for converter type modulator applications.

Science.gov (United States)

Reghu, T; Mandloi, V; Shrivastava, Purushottam

2016-04-01

The design and development of a compact high voltage, high peak power, high frequency transformer for a converter type modulator of klystron amplifiers is presented. The transformer has been designed to operate at a frequency of 20 kHz and at a flux swing of ±0.6 T. Iron (Fe) based nanocrystalline material has been selected as a core for the construction of the transformer. The transformer employs a specially designed solid Teflon bobbin having 120 kV insulation for winding the high voltage secondary windings. The flux swing of the core has been experimentally found by plotting the hysteresis loop at actual operating conditions. Based on the design, a prototype transformer has been built which is per se a unique combination of high voltage, high frequency, and peak power specifications. The transformer was able to provide 58 kV (pk-pk) at the secondary with a peak power handling capability of 700 kVA. The transformation ratio was 1:17. The performance of the transformer is also presented and discussed.

High Voltage Power Transmission for Wind Energy

Science.gov (United States)

Kim, Young il

The high wind speeds and wide available area at sea have recently increased the interests on offshore wind farms in the U.S.A. As offshore wind farms become larger and are placed further from the shore, the power transmission to the onshore grid becomes a key feature. Power transmission of the offshore wind farm, in which good wind conditions and a larger installation area than an onshore site are available, requires the use of submarine cable systems. Therefore, an underground power cable system requires unique design and installation challenges not found in the overhead power cable environment. This paper presents analysis about the benefit and drawbacks of three different transmission solutions: HVAC, LCC/VSC HVDC in the grid connecting offshore wind farms and also analyzed the electrical characteristics of underground cables. In particular, loss of HV (High Voltage) subsea power of the transmission cables was evaluated by the Brakelmann's theory, taking into account the distributions of current and temperature.

Properties of the ablation process for excimer laser ablation of Y sub 1 Ba sub 2 Cu sub 3 O sub 7

Energy Technology Data Exchange (ETDEWEB)

Neifeld, R.A.; Potenziani, E. (United States Army, Electronics Technology and Devices Laboratory, Fort Monmouth, New Jersey 07703-5000 (US)); Sinclair, W.R. (Martin Goffman Associates, 3 Dellview Drive, Edison, New Jersey 08820-2545 (US)); Hill III, W.T.; Turner, B.; Pinkas, A. (Institute for Physical Science and Technology, University of Maryland, College Park, Maryland 20742 (US))

1991-01-15

The process of excimer laser ablation has been studied while varying the laser fluence from 0.237 to 19.1 J/cm{sup 2}. Ion time-of-flight, total charge, target etch depth per pulse, and etch volume per pulse have been measured. Results indicate a maximum ablation volume and minimum ionization fraction occur near 5 J/cm{sup 2}. Several of the parameters measured vary rapidly in the 1--5 J/cm{sup 2} range. Variation in these parameters strongly influences the properties of films grown by this technique.

Highly red-shifted NIR emission from a novel anthracene conjugated polymer backbone containing Pt( ii ) porphyrins

KAUST Repository

Freeman, D. M. E.; Minotto, A.; Duffy, Warren; Fallon, K. J.; McCulloch, Iain; Cacialli, F.; Bronstein, H.

2015-01-01

-monomer is not limited to exclusively highly solubilising moieties. Interestingly, the polymer shows a red-shifted elecroluminescence maximum (510 nm) when compared to its photoluminescence maximum (450 nm) which we attribute to excimer formation. The novel polymer

High-energy power capacitors, their applied technology and the trends

International Nuclear Information System (INIS)

2012-01-01

High-voltage and high-energy-density power capacitors called high-power ones such as film or electrolytic capacitors, have been used in large quantities for the pulse power technology such as an impulse current or voltage generator and a laser power supply, and for the power electronics one with progress of the power semiconductor device and the inverter technology. Recently, electric double layer capacitors (EDLC) with remarkable technical progress have been applied for the equipments of electric power and industrial field for the purpose of energy saving or electric power quality improvement, which have come to link to the electric power system. Thus, using a lot of high-power capacitors near our life would require to know the structure, the principle and the characteristic of capacitors, and also to consider suitable directions for use, maintenance and safety and so on, when carrying out a system and a facility design. In the technical report, while describing the dielectric and the feature of some high-power capacitors, and introducing the application examples to the laser-fusion power supply and some systems with EDLC, the trend of standardization of EDLC and the directivity of the examination about installation and maintenance of the applied equipments are described. (author)

Improved cutting performance in high power laser cutting

DEFF Research Database (Denmark)

Olsen, Flemming Ove

2003-01-01

Recent results in high power laser cutting especially with focus on cutting of mild grade steel types for shipbuilding are described.......Recent results in high power laser cutting especially with focus on cutting of mild grade steel types for shipbuilding are described....

The high-power iodine laser

Science.gov (United States)

Brederlow, G.; Fill, E.; Witte, K. J.

The book provides a description of the present state of the art concerning the iodine laser, giving particular attention to the design and operation of pulsed high-power iodine lasers. The basic features of the laser are examined, taking into account aspects of spontaneous emission lifetime, hyperfine structure, line broadening and line shifts, stimulated emission cross sections, the influence of magnetic fields, sublevel relaxation, the photodissociation of alkyl iodides, flashlamp technology, excitation in a direct discharge, chemical excitation, and questions regarding the chemical kinetics of the photodissociation iodine laser. The principles of high-power operation are considered along with aspects of beam quality and losses, the design and layout of an iodine laser system, the scalability and prospects of the iodine laser, and the design of the single-beam Asterix III laser.

O impacto da cirurgia de ceratectomia fotorrefrativa (PRK e ceratomileuse assistida por excimer laser in situ (LASIK na qualidade visual e de vida em pacientes com ametropias The impact of photorefractive excimer laser keratectomy (PRK and laser in situ keratomileusis (LASIK on visual quality and life in patients with ametropias

Directory of Open Access Journals (Sweden)

Ricardo Belfort

2008-02-01

Full Text Available OBJETIVO: Avaliar a qualidade de vida e de visão e o estresse de pacientes portadores de ametropias submetidos a procedimentos cirúrgicos. MÉTODOS: Estudo longitudinal observacional em que foram estudados 100 pacientes; 54 usuários de óculos, 21 usuários de lentes de contato interessados no procedimento cirúrgico e 25 controles usuários de óculos ou lentes de contato, mas que não desejavam ser operados no período de um ano. Os questionários aplicados foram o National Eye Institute Visual Function Questionnaire (NEI-VFQ-25 de qualidade de vida e o Self Reporting Questionnaire - SRQ-20 para avaliação da saúde mental. Os pacientes que se submeteram à cirurgia responderam aos questionários aplicados por uma observadora antes da mesma, três, seis e doze meses após a intervenção. O grupo controle respondeu de forma auto-aplicada no início do estudo, seis e doze meses após a primeira avaliação. RESULTADOS: No grupo da cirugia dos 54 pacientes que usavam óculos 39 fizeram cirurgia de ceratectomia fotorrefrativa por excimer laser(PRK e 15 fizeram ceratomileuse assistida por excimer laserin situ (LASIK e dos 21 que usavam lentes de contato 12 fizeram cirurgia de ceratectomia fotorrefrativa e nove fizeram ceratomileuse assistida por excimer laser in situ (LASIK. O grupo controle esteve estável durante os 12 meses em relação aos instrumentos aplicados. Três meses após a cirurgia o grupo da cirurgia apresentou melhora significante da qualidade de vida e de visão em relação ao pré-operatório independentemente do tipo de cirurgia realizada. Um ano após a cirurgia os índices de qualidade de vida e de saúde mental, foram semelhantes aos do grupo controle. O Self Reporting Questionnaire - SRQ 20 mostrou diminuição significante do índice de sintomas a partir dos três meses de pós-operatório. CONCLUSÃO: A qualidade de visão e de vida dos pacientes submetidos à cirurgia de correção de ametropia mudou

GaN-based High Power High Frequency Wide Range LLC Resonant Converter, Phase I

Data.gov (United States)

National Aeronautics and Space Administration — SET Group will design, build and demonstrate a Gallium Nitride (GaN) based High Power High Frequency Wide Range LLC Resonant Converter capable of handling high power...

In-volume heating using high-power laser diodes

NARCIS (Netherlands)

Denisenkov, V.S.; Kiyko, V.V.; Vdovin, G.V.

2015-01-01

High-power lasers are useful instruments suitable for applications in various fields; the most common industrial applications include cutting and welding. We propose a new application of high-power laser diodes as in-bulk heating source for food industry. Current heating processes use surface

Active Snubber Circuit for High Power Inverter Leg

DEFF Research Database (Denmark)

Rasmussen, Tonny Wederberg; Johansen, Morten Holst

2009-01-01

Abstract— High power converters in the conventional 6 pulse configuration with 6 switching elements IGBTs (Insulated Gate Bipolar Transistor) are pushed to the limit of power. Especially the switching loss is high. This reduces the switching frequency due to cooling problems. Passive snubber circ...

Measurement of soft X-ray power from high-power Z-pinch plasma

International Nuclear Information System (INIS)

Wang Wensheng; Qiu Aici; Sun Fengrong; Luo Jianhui; Zhou Haisheng; He Duohui

2003-01-01

A Ni-film bolometer driven by the pulsed constant-voltage supply was developed for measuring soft X-ray energy under 1 keV generated from the Qiang-Guang-I, while the measuring system of the soft X-ray power was established with an X-ray diode detector. Results of the soft X-ray energy and power measurements were obtained at the experiment of Kr gas-puff high-power Z-pinch plasma

Modular High Voltage Power Supply

Energy Technology Data Exchange (ETDEWEB)

Newell, Matthew R. [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)

2017-05-18

The goal of this project is to develop a modular high voltage power supply that will meet the needs of safeguards applications and provide a modular plug and play supply for use with standard electronic racks.

High-Power Krypton Hall Thruster Technology Being Developed for Nuclear-Powered Applications

Science.gov (United States)

Jacobson, David T.; Manzella, David H.

2004-01-01

The NASA Glenn Research Center has been performing research and development of moderate specific impulse, xenon-fueled, high-power Hall thrusters for potential solar electric propulsion applications. These applications include Mars missions, reusable tugs for low-Earth-orbit to geosynchronous-Earth-orbit transportation, and missions that require transportation to libration points. This research and development effort resulted in the design and fabrication of the NASA-457M Hall thruster that has been tested at input powers up to 95 kW. During project year 2003, NASA established Project Prometheus to develop technology in the areas of nuclear power and propulsion, which are enabling for deep-space science missions. One of the Project-Prometheus-sponsored Nuclear Propulsion Research tasks is to investigate alternate propellants for high-power Hall thruster electric propulsion. The motivation for alternate propellants includes the disadvantageous cost and availability of xenon propellant for extremely large scale, xenon-fueled propulsion systems and the potential system performance benefits of using alternate propellants. The alternate propellant krypton was investigated because of its low cost relative to xenon. Krypton propellant also has potential performance benefits for deep-space missions because the theoretical specific impulse for a given voltage is 20 percent higher than for xenon because of krypton's lower molecular weight. During project year 2003, the performance of the high-power NASA-457M Hall thruster was measured using krypton as the propellant at power levels ranging from 6.4 to 72.5 kW. The thrust produced ranged from 0.3 to 2.5 N at a discharge specific impulse up to 4500 sec.

Thulium heat source for high-endurance and high-energy density power systems

International Nuclear Information System (INIS)

Walter, C.E.; Kammeraad, J.E.; Van Konynenburg, R.; VanSant, J.H.

1991-05-01

We are studying the performance characteristics of radioisotope heat source designs for high-endurance and high-energy-density power systems that use thulium-170. Heat sources in the power range of 5--50 kW th coupled with a power conversion efficiency of ∼30%, can easily satisfy current missions for autonomous underwater vehicles. New naval missions will be possible because thulium isotope power systems have a factor of one-to-two hundred higher endurance and energy density than chemical and electrochemical systems. Thulium-170 also has several other attractive features, including the fact that it decays to stable ytterbium-170 with a half-life of four months. For terrestrial applications, refueling on that time scale should be acceptable in view of the advantage of its benign decay. The heat source designs we are studying account for the requirements of isotope production, shielding, and integration with power conversion components. These requirements are driven by environmental and safety considerations. Thulium is present in the form of thin refractory thulia disks that allow power conversion at high peak temperature. We give estimates of power system state points, performance, mass, and volume characteristics. Monte Carlo radiation analysis provides a detailed assessment of shield requirements and heat transfer under normal and distressed conditions is also considered. 11 refs., 7 figs., 4 tabs

Laser-induced-fluorescence imaging of NO in a eta-heptane- and diesel-fuel-driven diesel engine

NARCIS (Netherlands)

Brugman, T.M.; Klein-Douwel, R.J.H.; Huigen, G.; Walwijk, van E.; Meulen, ter J.J.

1993-01-01

Continuous on-line imaging by 2D-LIF techniques of in-cylinder NO distributions in a running Diesel engine is explored using an ArF-excimer laser at 193 nm operating at low power. For the first time NO excitation spectra could be measured as a result of high optical transparencies during

High power pulsed sources based on fiber amplifiers

Science.gov (United States)

Canat, Guillaume; Jaouën, Yves; Mollier, Jean-Claude; Bouzinac, Jean-Pierre; Cariou, Jean-Pierre

2017-11-01

Cladding-pumped rare-earth-doped fiber laser technologies are currently among the best sources for high power applications. Theses extremely compact and robust sources appoint them as good candidate for aeronautical and space applications. The double-clad (DC) fiber converts the poor beamquality of high-power large-area pump diodes from the 1st cladding to laser light at another wavelength guided in an active single-mode core. High-power coherent MOPA (Master Oscillator Power Amplifier) sources (several 10W CW or several 100W in pulsed regime) will soon be achieved. Unfortunately it also brings nonlinear effects which quickly impairs output signal distortions. Stimulated Brillouin scattering (SBS) and optical parametric amplification (OPA) have been shown to be strong limitations. Based on amplifier modeling and experiments we discuss the performances of these sources.

High Power Density Motors

Science.gov (United States)

Kascak, Daniel J.

2004-01-01

With the growing concerns of global warming, the need for pollution-free vehicles is ever increasing. Pollution-free flight is one of NASA's goals for the 21" Century. , One method of approaching that goal is hydrogen-fueled aircraft that use fuel cells or turbo- generators to develop electric power that can drive electric motors that turn the aircraft's propulsive fans or propellers. Hydrogen fuel would likely be carried as a liquid, stored in tanks at its boiling point of 20.5 K (-422.5 F). Conventional electric motors, however, are far too heavy (for a given horsepower) to use on aircraft. Fortunately the liquid hydrogen fuel can provide essentially free refrigeration that can be used to cool the windings of motors before the hydrogen is used for fuel. Either High Temperature Superconductors (HTS) or high purity metals such as copper or aluminum may be used in the motor windings. Superconductors have essentially zero electrical resistance to steady current. The electrical resistance of high purity aluminum or copper near liquid hydrogen temperature can be l/lOO* or less of the room temperature resistance. These conductors could provide higher motor efficiency than normal room-temperature motors achieve. But much more importantly, these conductors can carry ten to a hundred times more current than copper conductors do in normal motors operating at room temperature. This is a consequence of the low electrical resistance and of good heat transfer coefficients in boiling LH2. Thus the conductors can produce higher magnetic field strengths and consequently higher motor torque and power. Designs, analysis and actual cryogenic motor tests show that such cryogenic motors could produce three or more times as much power per unit weight as turbine engines can, whereas conventional motors produce only 1/5 as much power per weight as turbine engines. This summer work has been done with Litz wire to maximize the current density. The current is limited by the amount of heat it

Welding with high power fiber lasers - A preliminary study

International Nuclear Information System (INIS)

Quintino, L.; Costa, A.; Miranda, R.; Yapp, D.; Kumar, V.; Kong, C.J.

2007-01-01

The new generation of high power fiber lasers presents several benefits for industrial purposes, namely high power with low beam divergence, flexible beam delivery, low maintenance costs, high efficiency and compact size. This paper presents a brief review of the development of high power lasers, and presents initial data on welding of API 5L: X100 pipeline steel with an 8 kW fiber laser. Weld bead geometry was evaluated and transition between conduction and deep penetration welding modes was investigated

Very High Frequency Switch-Mode Power Supplies

DEFF Research Database (Denmark)

Madsen, Mickey Pierre

The importance of technology and electronics in our daily life is constantly increasing. At the same time portability and energy efficiency are currently some of the hottest topics. This creates a huge need for power converters in a compact form factor and with high efficiency, which can supply...... these electronic devices. This calls for new technologies in order to miniaturize the power electronics of today. One way to do this is by increasing the switching frequency dramatically and develop very high frequency switch mode power supplies. If these converters can be designed to operate efficiently, a huge...... size, weight and cost reduction can be achieved due to the smaller energy storing elements needed at these frequencies. The research presented in this thesis focuses on exactly this. First various technologies for miniaturization of power supplies are studied, e.g. piezo electric transformers, wide...

April 25, 2003, FY2003 Progress Summary and FY2002 Program Plan, Statement of Work and Deliverables for Development of High Average Power Diode-Pumped Solid State Lasers,and Complementary Technologies, for Applications in Energy and Defense

International Nuclear Information System (INIS)

Meier, W; Bibeau, C

2005-01-01

The High Average Power Laser Program (HAPL) is a multi-institutional, synergistic effort to develop inertial fusion energy (IFE). This program is building a physics and technology base to complement the laser-fusion science being pursued by DOE Defense programs in support of Stockpile Stewardship. The primary institutions responsible for overseeing and coordinating the research activities are the Naval Research Laboratory (NRL) and Lawrence Livermore National Laboratory (LLNL). The current LLNL proposal is a companion document to the one submitted by NRL, for which the driver development element is focused on the krypton fluoride excimer laser option. The NRL and LLNL proposals also jointly pursue complementary activities with the associated rep-rated laser technologies relating to target fabrication, target injection, final optics, fusion chamber, target physics, materials and power plant economics. This proposal requests continued funding in FY03 to support LLNL in its program to build a 1 kW, 100 J, diode-pumped, crystalline laser, as well as research into high gain fusion target design, fusion chamber issues, and survivability of the final optic element. These technologies are crucial to the feasibility of inertial fusion energy power plants and also have relevance in rep-rated stewardship experiments. The HAPL Program pursues technologies needed for laser-driven IFE. System level considerations indicate that a rep-rated laser technology will be needed, operating at 5-10 Hz. Since a total energy of ∼2 MJ will ultimately be required to achieve suitable target gain with direct drive targets, the architecture must be scaleable. The Mercury Laser is intended to offer such an architecture. Mercury is a solid state laser that incorporates diodes, crystals and gas cooling technologies

Social power and recognition of emotional prosody: High power is associated with lower recognition accuracy than low power.

Science.gov (United States)

Uskul, Ayse K; Paulmann, Silke; Weick, Mario

2016-02-01

Listeners have to pay close attention to a speaker's tone of voice (prosody) during daily conversations. This is particularly important when trying to infer the emotional state of the speaker. Although a growing body of research has explored how emotions are processed from speech in general, little is known about how psychosocial factors such as social power can shape the perception of vocal emotional attributes. Thus, the present studies explored how social power affects emotional prosody recognition. In a correlational study (Study 1) and an experimental study (Study 2), we show that high power is associated with lower accuracy in emotional prosody recognition than low power. These results, for the first time, suggest that individuals experiencing high or low power perceive emotional tone of voice differently. (c) 2016 APA, all rights reserved).

Study of novel plasma devices generated by high power lasers coupled with a micro-pulse power technology

International Nuclear Information System (INIS)

Nishida, A; Chen, Z L; Jin, Z; Kondo, K; Nakagawa, M; Kodama, R; Arima, H; Yoneda, H

2008-01-01

The authors have proposed introducing a micro pulse power technology in high power laser plasma experiments to boost up the return current, resulting in efficiently guiding of energetic electrons. High current pulse power generators with a pulse laser trigger system generate high-density plasma that is well conductor. To efficiently guiding by using a micro pulse power, we estimated parameter of a micro pulse power system that is voltage of rise time, current, charging voltage and capacitance

Solid state pump lasers with high power and high repetition rate

International Nuclear Information System (INIS)

Oba, Masaki; Kato, Masaaki; Arisawa, Takashi

1995-01-01

We built a laser diode pumped solid state green laser (LDPSSGL) rated at high repetition rate. Two laser heads are placed in one cavity with a rotator in between to design to avoid thermal lensing and thermal birefringence effect. Although average green laser power higher than 10 W was obtained at 1 kHz repetition rate with pulse width of 20-30 nsec, the beam quality was so much deteriorated that energy efficiency was as low as 2 %. Learning from this experience that high power oscillator causes a lot of thermal distortion not only in the laser rod but also in the Q-switch device, we proceeded to built a oscillator/amplifier system. A low power oscillator has a slab type crystal in the cavity. As a result spatial distribution of laser power was extremely improved. As we expect that the high repetition rate solid state laser should be CW operated Q-switch type laser from the view point of lifetime of diode lasers, a conventional arc lamp pumped CW Q-switch green YAG laser of which the repetition rate is changeable from 1 kHz to 5 kHz and the pulse width is 250-570 nsec was also tested to obtain pumping characteristics of a dye laser as a function of power, pulse width etc., and dye laser pulse width of 100-130 nsec were obtained. (author)

High-power electronics

CERN Document Server

Kapitsa, Petr Leonidovich

1966-01-01

High-Power Electronics, Volume 2 presents the electronic processes in devices of the magnetron type and electromagnetic oscillations in different systems. This book explores the problems of electronic energetics.Organized into 11 chapters, this volume begins with an overview of the motion of electrons in a flat model of the magnetron, taking into account the in-phase wave and the reverse wave. This text then examines the processes of transmission of electromagnetic waves of various polarization and the wave reflection from grids made of periodically distributed infinite metal conductors. Other

Design methods for high temperature power plant structures

International Nuclear Information System (INIS)

Townley, C.H.A.

1984-01-01

The subject is discussed under the headings: introduction (scope of paper - reviews of design methods and design criteria currently in use for both nuclear and fossil fuelled power plant; examples chosen are (a) BS 1113, representative of design codes employed for power station boiler plant; (b) ASME Code Case N47, which is being developed for high temperature nuclear reactors, especially the liquid metal fast breeder reactor); design codes for power station boilers; Code Case N47 (design in the absence of thermal shock and thermal fatigue; design against cyclic loading at high temperature; further research in support of high temperature design methods and criteria for LMFBRs); concluding remarks. (U.K.)

High performance protection circuit for power electronics applications

Energy Technology Data Exchange (ETDEWEB)

Tudoran, Cristian D., E-mail: cristian.tudoran@itim-cj.ro; Dădârlat, Dorin N.; Toşa, Nicoleta; Mişan, Ioan [National Institute for Research and Development of Isotopic and Molecular Technologies, 67-103 Donat, PO 5 Box 700, 400293 Cluj-Napoca (Romania)

2015-12-23

In this paper we present a high performance protection circuit designed for the power electronics applications where the load currents can increase rapidly and exceed the maximum allowed values, like in the case of high frequency induction heating inverters or high frequency plasma generators. The protection circuit is based on a microcontroller and can be adapted for use on single-phase or three-phase power systems. Its versatility comes from the fact that the circuit can communicate with the protected system, having the role of a “sensor” or it can interrupt the power supply for protection, in this case functioning as an external, independent protection circuit.

Preliminary design of high-power wave-guide/transmission system

Indian Academy of Sciences (India)

... CW klystron followed by wave-guide filter, dual directional coupler, high-power circulator, three 3 dB magic TEE power dividers to split the main channel into four equal channels of 250 kW each. Each individual channel has dual directional couplers, flexible wave-guide sections and high power ceramic vacuum window.

High technology supporting nuclear power industry in CRIEPI

International Nuclear Information System (INIS)

Ueda, Nobuyuki

2009-01-01

As a central research institute of electric power industry, Central Research Institute of Electric Power Industry (CRIEPI) has carried out R and D on broad range of topics such as power generation, power transmission, power distribution, power application and energy economics and society, aiming to develop prospective and advanced technologies, fundamental reinforce technologies and next-generation core technologies. To realize low-carbon society to cope with enhancement of global environmental issues, nuclear power is highly recommended as large-scale power with low-carbon emission. At the new start of serial explanation on advanced technologies, R and D on electric power industry was outlined. (T. Tanaka)

Randomized controlled study of excimer laser atherectomy for treatment of femoropopliteal in-stent restenosis: initial results from the EXCITE ISR trial (EXCImer Laser Randomized Controlled Study for Treatment of FemoropopliTEal In-Stent Restenosis).

Science.gov (United States)

Dippel, Eric J; Makam, Prakash; Kovach, Richard; George, Jon C; Patlola, Raghotham; Metzger, D Christopher; Mena-Hurtado, Carlos; Beasley, Robert; Soukas, Peter; Colon-Hernandez, Pedro J; Stark, Matthew A; Walker, Craig

2015-01-01

The purpose of this study was to evaluate the safety and efficacy of excimer laser atherectomy (ELA) with adjunctive percutaneous transluminal angioplasty (PTA) versus PTA alone for treating patients with chronic peripheral artery disease with femoropopliteal bare nitinol in-stent restenosis (ISR). Femoropopliteal stenting has shown superiority to PTA for lifestyle-limiting claudication and critical limb ischemia, although treating post-stenting artery reobstruction, or ISR, remains challenging. The multicenter, prospective, randomized, controlled EXCITE ISR (EXCImer Laser Randomized Controlled Study for Treatment of FemoropopliTEal In-Stent Restenosis) trial was conducted across 40 U.S. centers. Patients with Rutherford Class 1 to 4 and lesions of target lesion length ≥4 cm, vessel diameter 5 to 7 mm were enrolled and randomly divided into ELA + PTA and PTA groups by a 2:1 ratio. The primary efficacy endpoint was target lesion revascularization (TLR) at 6-month follow up. The primary safety endpoint was major adverse event (death, amputation, or TLR) at 30 days post-procedure. Study enrollment was stopped at 250 patients due to early efficacy demonstrated at a prospectively-specified interim analysis. A total of 169 ELA + PTA subjects (62.7% male; mean age 68.5 ± 9.8 years) and 81 PTA patients (61.7% male; mean age 67.8 ± 10.3 years) were enrolled. Mean lesion length was 19.6 ± 12.0 cm versus 19.3 ± 11.9 cm, and 30.5% versus 36.8% of patients exhibited total occlusion. ELA + PTA subjects demonstrated superior procedural success (93.5% vs. 82.7%; p = 0.01) with significantly fewer procedural complications. ELA + PTA and PTA subject 6-month freedom from TLR was 73.5% versus 51.8% (p < 0.005), and 30-day major adverse event rates were 5.8% versus 20.5% (p < 0.001), respectively. ELA + PTA was associated with a 52% reduction in TLR (hazard ratio: 0.48; 95% confidence interval: 0.31 to 0.74). The EXCITE ISR trial is the first large, prospective, randomized study

Development and advances in conventional high power RF systems

International Nuclear Information System (INIS)

Wilson, P.B.

1995-06-01

The development of rf systems capable of producing high peak power (hundreds of megawatts) at relatively short pulse lengths (0.1--5 microseconds) is currently being driven mainly by the requirements of future high energy linear colliders, although there may be applications to industrial, medical and research linacs as well. The production of high peak power rf typically involves four basic elements: a power supply to convert ac from the ''wall plug'' to dc; a modulator, or some sort of switching element, to produce pulsed dc power; an rf source to convert the pulsed dc to pulsed rf power; and possibly an rf pulse compression system to further enhance the peak rf power. Each element in this rf chain from wall plug to accelerating structure must perform with high efficiency in a linear collider application, such that the overall system efficiency is 30% or more. Basic design concepts are discussed for klystrons, modulators and rf pulse compression systems, and their present design status is summarized for applications to proposed linear colliders

Industrial applications of high-average power high-peak power nanosecond pulse duration Nd:YAG lasers

Science.gov (United States)

Harrison, Paul M.; Ellwi, Samir

2009-02-01

Within the vast range of laser materials processing applications, every type of successful commercial laser has been driven by a major industrial process. For high average power, high peak power, nanosecond pulse duration Nd:YAG DPSS lasers, the enabling process is high speed surface engineering. This includes applications such as thin film patterning and selective coating removal in markets such as the flat panel displays (FPD), solar and automotive industries. Applications such as these tend to require working spots that have uniform intensity distribution using specific shapes and dimensions, so a range of innovative beam delivery systems have been developed that convert the gaussian beam shape produced by the laser into a range of rectangular and/or shaped spots, as required by demands of each project. In this paper the authors will discuss the key parameters of this type of laser and examine why they are important for high speed surface engineering projects, and how they affect the underlying laser-material interaction and the removal mechanism. Several case studies will be considered in the FPD and solar markets, exploring the close link between the application, the key laser characteristics and the beam delivery system that link these together.

Cascade: a high-efficiency ICF power reactor

International Nuclear Information System (INIS)

Pitts, J.H.

1985-01-01

Cascade attains a net power-plant efficiency of 49% and its cost is competitive with high-temperature gas-cooled reactor, pressurized-water reactor, and coal-fired power plants. The Cascade reactor and blanket are made of ceramic materials and activation is 6 times less than that of the MARS Tandem Mirror Reactor operating at comparable power. Hands-on maintenance of the heat exchangers is possible one day after shutdown. Essentially all tritium is recovered in the vacuum system, with the remainder recovered from the helium power conversion loop. Tritium leakage external to the vacuum system and power conversion loop is only 0.03 Ci/d

High power rf component testing for the NLC

International Nuclear Information System (INIS)

Vlieks, A.E.; Fowkes, W.R.; Loewen, R.J.; Tantawi, S.G.

1998-09-01

In the Next Linear Collider (NLC), the high power rf components must be capable of handling peak rf power levels in excess of 600 MW. In the current view of the NLC, even the rectangular waveguide components must transmit at least 300 MW rf power. At this power level, peak rf fields can greatly exceed 100 MV/m. The authors present recent results of high power tests performed at the Accelerator Structure Test Area (ASTA) at SLAC. These tests are designed to investigate the rf breakdown limits of several new components potentially useful for the NLC. In particular, the authors tested a new TE 01 --TE 10 circular to rectangular wrap-around mode converter, a modified (internal fin) Magic Tee hybrid, and an upgraded flower petal mode converter

High power coaxial ubitron

Science.gov (United States)

Balkcum, Adam J.

In the ubitron, also known as the free electron laser, high power coherent radiation is generated from the interaction of an undulating electron beam with an electromagnetic signal and a static periodic magnetic wiggler field. These devices have experimentally produced high power spanning the microwave to x-ray regimes. Potential applications range from microwave radar to the study of solid state material properties. In this dissertation, the efficient production of high power microwaves (HPM) is investigated for a ubitron employing a coaxial circuit and wiggler. Designs for the particular applications of an advanced high gradient linear accelerator driver and a directed energy source are presented. The coaxial ubitron is inherently suited for the production of HPM. It utilizes an annular electron beam to drive the low loss, RF breakdown resistant TE01 mode of a large coaxial circuit. The device's large cross-sectional area greatly reduces RF wall heat loading and the current density loading at the cathode required to produce the moderate energy (500 keV) but high current (1-10 kA) annular electron beam. Focusing and wiggling of the beam is achieved using coaxial annular periodic permanent magnet (PPM) stacks without a solenoidal guide magnetic field. This wiggler configuration is compact, efficient and can propagate the multi-kiloampere electron beams required for many HPM applications. The coaxial PPM ubitron in a traveling wave amplifier, cavity oscillator and klystron configuration is investigated using linear theory and simulation codes. A condition for the dc electron beam stability in the coaxial wiggler is derived and verified using the 2-1/2 dimensional particle-in-cell code, MAGIC. New linear theories for the cavity start-oscillation current and gain in a klystron are derived. A self-consistent nonlinear theory for the ubitron-TWT and a new nonlinear theory for the ubitron oscillator are presented. These form the basis for simulation codes which, along

High-resolution wavefront control of high-power laser systems

International Nuclear Information System (INIS)

Brase, J.; Brown, C.; Carrano, C.; Kartz, M.; Olivier, S.; Pennington, D.; Silva, D.

1999-01-01

Nearly every new large-scale laser system application at LLNL has requirements for beam control which exceed the current level of available technology. For applications such as inertial confinement fusion, laser isotope separation, laser machining, and laser the ability to transport significant power to a target while maintaining good beam quality is critical. There are many ways that laser wavefront quality can be degraded. Thermal effects due to the interaction of high-power laser or pump light with the internal optical components or with the ambient gas are common causes of wavefront degradation. For many years, adaptive optics based on thing deformable glass mirrors with piezoelectric or electrostrictive actuators have be used to remove the low-order wavefront errors from high-power laser systems. These adaptive optics systems have successfully improved laser beam quality, but have also generally revealed additional high-spatial-frequency errors, both because the low-order errors have been reduced and because deformable mirrors have often introduced some high-spatial-frequency components due to manufacturing errors. Many current and emerging laser applications fall into the high-resolution category where there is an increased need for the correction of high spatial frequency aberrations which requires correctors with thousands of degrees of freedom. The largest Deformable Mirrors currently available have less than one thousand degrees of freedom at a cost of approximately $1M. A deformable mirror capable of meeting these high spatial resolution requirements would be cost prohibitive. Therefore a new approach using a different wavefront control technology is needed. One new wavefront control approach is the use of liquid-crystal (LC) spatial light modulator (SLM) technology for the controlling the phase of linearly polarized light. Current LC SLM technology provides high-spatial-resolution wavefront control, with hundreds of thousands of degrees of freedom, more

Modular high voltage power supply for chemical analysis

Science.gov (United States)

Stamps, James F [Livermore, CA; Yee, Daniel D [Dublin, CA

2008-07-15

A high voltage power supply for use in a system such as a microfluidics system, uses a DC-DC converter in parallel with a voltage-controlled resistor. A feedback circuit provides a control signal for the DC-DC converter and voltage-controlled resistor so as to regulate the output voltage of the high voltage power supply, as well as, to sink or source current from the high voltage supply.

Design of a high-power, high-brightness Nd:YAG solar laser.

Science.gov (United States)

Liang, Dawei; Almeida, Joana; Garcia, Dário

2014-03-20

A simple high-power, high-brightness Nd:YAG solar laser pumping approach is presented in this paper. The incoming solar radiation is both collected and concentrated by four Fresnel lenses and redirected toward a Nd:YAG laser head by four plane-folding mirrors. A fused-silica secondary concentrator is used to compress the highly concentrated solar radiation to a laser rod. Optimum pumping conditions and laser resonator parameters are found through ZEMAX and LASCAD numerical analysis. Solar laser power of 96 W is numerically calculated, corresponding to the collection efficiency of 24  W/m². A record-high solar laser beam brightness figure of merit of 9.6 W is numerically achieved.

Effect of excimer laser annealing on a-InGaZnO thin-film transistors passivated by solution-processed hybrid passivation layers

International Nuclear Information System (INIS)

Bermundo, Juan Paolo; Ishikawa, Yasuaki; Fujii, Mami N; Uraoka, Yukiharu; Nonaka, Toshiaki; Ishihara, Ryoichi; Ikenoue, Hiroshi

2016-01-01

We demonstrate the use of excimer laser annealing (ELA) as a low temperature annealing alternative to anneal amorphous InGaZnO (a-IGZO) thin-film transistors (TFTs) passivated by a solution-processed hybrid passivation layer. Usually, a-IGZO is annealed using thermal annealing at high temperatures of up to 400 °C. As an alternative to high temperature thermal annealing, two types of ELA, XeCl (308 nm) and KrF (248 nm) ELA, are introduced. Both ELA types enhanced the electrical characteristics of a-IGZO TFTs leading to a mobility improvement of ∼13 cm 2 V −1 s −1 and small threshold voltage which varied from ∼0–3 V. Furthermore, two-dimensional heat simulation using COMSOL Multiphysics was used to identify possible degradation sites, analyse laser heat localization, and confirm that the substrate temperature is below 50 °C. The two-dimensional heat simulation showed that the substrate temperature remained at very low temperatures, less than 30 °C, during ELA. This implies that any flexible material can be used as the substrate. These results demonstrate the large potential of ELA as a low temperature annealing alternative for already-passivated a-IGZO TFTs. (paper)

High Power Radiation Tolerant CubeSat Power System, Phase I

Data.gov (United States)

National Aeronautics and Space Administration — No vendor has yet to provide a radiation tolerant, high efficiency, small Power Management and Distribution module for the SmallSat and CubeSat market yet. Let alone...

High Input Voltage, Silicon Carbide Power Processing Unit Performance Demonstration

Science.gov (United States)

Bozak, Karin E.; Pinero, Luis R.; Scheidegger, Robert J.; Aulisio, Michael V.; Gonzalez, Marcelo C.; Birchenough, Arthur G.

2015-01-01

A silicon carbide brassboard power processing unit has been developed by the NASA Glenn Research Center in Cleveland, Ohio. The power processing unit operates from two sources: a nominal 300 Volt high voltage input bus and a nominal 28 Volt low voltage input bus. The design of the power processing unit includes four low voltage, low power auxiliary supplies, and two parallel 7.5 kilowatt (kW) discharge power supplies that are capable of providing up to 15 kilowatts of total power at 300 to 500 Volts (V) to the thruster. Additionally, the unit contains a housekeeping supply, high voltage input filter, low voltage input filter, and master control board, such that the complete brassboard unit is capable of operating a 12.5 kilowatt Hall effect thruster. The performance of the unit was characterized under both ambient and thermal vacuum test conditions, and the results demonstrate exceptional performance with full power efficiencies exceeding 97%. The unit was also tested with a 12.5kW Hall effect thruster to verify compatibility and output filter specifications. With space-qualified silicon carbide or similar high voltage, high efficiency power devices, this would provide a design solution to address the need for high power electric propulsion systems.

High Power RF Transmitters for ICRF Applications on EAST

International Nuclear Information System (INIS)

Mao Yuzhou; Yuan Shuai; Zhao Yanping; Zhang Xinjun; Chen Gen; Cheng Yan; Wang Lei; Ju Songqing; Deng Xu; Qin Chengming; Yang Lei; Kumazawa, R.