Study of reverse Brayton cryocooler with Helium-Neon mixture for HTS cable

Science.gov (United States)

Dhillon, A. K.; Ghosh, P.

2017-12-01

As observed in the earlier studies, helium is more efficient than neon as a refrigerant in a reverse Brayton cryocooler (RBC) from the thermodynamic point of view. However, the lower molecular weight of helium leads to higher refrigerant inventory as compared to neon. Thus, helium is suitable to realize the high thermodynamic efficiency of RBC whereas neon is appropriate for the compactness of the RBC. A binary mixture of helium and neon can be used to achieve high thermodynamic efficiency in the compact reverse Brayton cycle (RBC) based cryocooler. In this paper, an attempt has been made to analyze the thermodynamic performance of the RBC with a binary mixture of helium and neon as the working fluid to provide 1 kW cooling load for high temperature superconductor (HTS) power cables working with a temperature range of 50 K to 70 K. The basic RBC is simulated using Aspen HYSYS V8.6®, a commercial process simulator. Sizing of each component based on the optimized process parameters for each refrigerant is performed based on a computer code developed using Engineering Equation Solver (EES-V9.1). The recommendation is provided for the optimum mixture composition of the refrigerant based on the trade-off factors like thermodynamic efficiency such as the exergy efficiency and equipment considerations. The outcome of this study may be useful for recommending a suitable refrigerant for the RBC operating at a temperature level of 50 K to 70 K.

Fragmentation dynamics of ionized neon trimer inside helium nanodroplets: a theoretical study.

Science.gov (United States)

Bonhommeau, David; Viel, Alexandra; Halberstadt, Nadine

2004-06-22

We report a theoretical study of the fragmentation dynamics of Ne(3) (+) inside helium nanodroplets, following vertical ionization of the neutral neon trimer. The motion of the neon atoms is treated classically, while transitions between the electronic states of the ionic cluster are treated quantum mechanically. A diatomics-in-molecules description of the potential energy surfaces is used, in a minimal basis set consisting of three effective p orbitals on each neon atom for the missing electron. The helium environment is modeled by a friction force acting on the neon atoms when their speed exceeds the Landau velocity. A reasonable range of values for the corresponding friction coefficient is obtained by comparison with existing experimental measurements. (c) 2004 American Institute of Physics.

Low energy helium-neon laser prevents oral mucositis after high-dose chemo-radiotherapy: results of a double-blind randomized trial

International Nuclear Information System (INIS)

Cowen, Didier; Tardieu, Corinne; Resbeut, Michel; Hannoun-Levi, Jean-Michel; Alzieu, Claude; Schubert, Marc; Franquin, Jean-Claude

1996-01-01

Purpose: To evaluate the efficiency of Helium-Neon (He-Ne) laser in the prevention of oral mucositis (OM) induced by high dose chemoradiotherapy before bone marrow transplantation (BMT). Methods and materials: Between 1993 and 1995, 30 consecutive patients (pts) receiving an autologous peripheral stem-cell or bone marrow transplant (BMT) after high dose chemoradiotherapy were randomized to receive or not prophylactic laser applications to the oral mucosa. Chemotherapy consisted of cyclophosphamide, 60 mg/kg intravenously (IV) on day (d)-5 and d-4 in 27 cases, or melphalan 140 mg/kg IV on d-4 in 3 cases. Total body irradiation consisted of 12 Gy midplane dose in six fractions and 3 days. He-Ne laser (632.8 nm wavelength, power 60 mW) applications were performed daily from d-5 to d-1 on 5 anatomic sites of the oral mucosa. Oral examination was performed daily from d0 to d+20. Mucositis was scored according to an oral exam guide with a 16 items scale of which 4 were assessed by the pts themselves. Mean daily scores of pain, ability to swallow and saliva production were measured. A daily mucositis index (DMI) and a cumulative score of oral mucositis (CSOM) were established. Requirement for narcotics and parenteral nutrition were measured. Validation of the grading scale was carried out using the Cronbach alpha coefficient for the internal validation and the test-retest correlation coefficient for the reproducibility analysis. The U Mann Whitney test was used to test for differences among groups. Patients were assigned to either laser treatment (L+) or sham-treatment (L-) by computer blocked randomization. Results: No pt was excluded for failure to complete the laser application protocol. Laser applications were well tolerated and no side effects were reported. The items were highly interrelated as well as the index considered as a whole: over 21 days, α = 0.97. Reproducibility analysis between the nurses in charge with the oral examination showed a significant

Low-level laser therapy with helium-neon laser improved viability of osteoporotic bone marrow-derived mesenchymal stem cells from ovariectomy-induced osteoporotic rats

Science.gov (United States)

Fallahnezhad, Somaye; Piryaei, Abbas; Tabeie, Faraj; Nazarian, Hamid; Darbandi, Hasan; Amini, Abdoldllah; Mostafavinia, Ataroalsadat; Ghorishi, Seyed Kamran; Jalalifirouzkouhi, Ali; Bayat, Mohammad

2016-09-01

The purpose of this study was to evaluate the influences of helium-neon (He-Ne) and infrared (IR) lasers on the viability and proliferation rate of healthy and ovariectomy-induced osteoporotic (OVX) bone marrow mesenchymal stem cells (BMMSCs) in vitro. MSCs harvested from the BM of healthy and OVX rats were culture expanded. He-Ne and IR lasers were applied three times at energy densities of 0.6, 1.2, and 2.4 J/cm2 for BMMSCs. BMMSCs viability and proliferation rate were evaluated by MTT assay on days 2, 4, 6, 14, and 21. The results showed that healthy BMMSCs responded optimally to 0.6 J/cm2 using an IR laser after three times of laser radiation. Moreover, it was found that OVX-BMMSCs responded optimally to 0.6 J/cm2 with He-Ne laser and one-time laser radiation. It is concluded that the low-level laser therapy (LLLT) effect depends on the physiological state of the BMMSCs, type of the laser, wavelength, and number of laser sessions. The biostimulation efficiency of LLLT also depends on the delivered energy density. LLLT can enhance the viability and proliferation rate of healthy and especially osteoporotic autologous BMMSCs, which could be very useful in regenerative medicine.

Utilizing Neon Ion Microscope for GaSb nanopatterning studies: Nanostructure formation and comparison with low energy nanopatterning

International Nuclear Information System (INIS)

El-Atwani, Osman; Huynh, Chuong; Norris, Scott

2016-01-01

Graphical abstract: - Highlights: • Carl Zeiss-neon ion microscope was used to irradiated GaSb surfaces with 5 keV neon. • In-situ imaging using helium beam and ex-situ imaging using an electron beam were performed. • Differences in imaging output between the helium and the electron beam were observed. • Transition occurred in the nanostructure type and formation mechanism as the energy is changed from 2 to 5 keV. • Collision cascade simulations suggested a transition toward bulk-driven mechanisms. - Abstract: Low energy irradiation of GaSb surfaces has been shown to lead to nanopillar formation. Being performed ex-situ, controlling the parameters of the ion beam for controlled nanopattern formation is challenging. While mainly utilized for imaging and cutting purposes, the development of multibeam (helium/neon) ion microscopes has opened the path towards the use of these microscopes for in-situ ion irradiation and nanopatterning studies. In this study, in-situ irradiation (neon ions)/imaging (helium ions) of GaSb surfaces is performed using Carl Zeiss-neon ion microscope at low energies (5 and 10 keV). Imaging with helium ions, nanodots were shown to form at particular fluences after which are smoothed. Ex-situ imaging with SEM showed nanopore formation of size controlled by the ion energy and fluence. Compared to lower energy ex-situ neon ion irradiation at similar fluxes, where nanopillars are formed, the results demonstrated a transition in the nanostructure type and formation mechanism as the energy is changed from 2 to 5 keV. Simulations show an increase in the ballistic diffusion and a decrease in the strength of phase separation as a function of ion energy in agreement with the suppression of nanopillar formation at higher energies. Collision cascade simulations suggest a transition toward bulk-driven mechanisms.

Utilizing Neon Ion Microscope for GaSb nanopatterning studies: Nanostructure formation and comparison with low energy nanopatterning

Energy Technology Data Exchange (ETDEWEB)

El-Atwani, Osman, E-mail: oelatwan25@gmail.com [School of Nuclear Engineering, Purdue University, West Lafayette, Indiana 47907 (United States); Huynh, Chuong [Carl Zeiss Microscopy, LLC, One Corporation Way, Peabody, MA 01960 (United States); Norris, Scott [Department of Mathematics, Southern Methodist University, Dallas, TX 75275 (United States)

2016-05-01

Graphical abstract: - Highlights: • Carl Zeiss-neon ion microscope was used to irradiated GaSb surfaces with 5 keV neon. • In-situ imaging using helium beam and ex-situ imaging using an electron beam were performed. • Differences in imaging output between the helium and the electron beam were observed. • Transition occurred in the nanostructure type and formation mechanism as the energy is changed from 2 to 5 keV. • Collision cascade simulations suggested a transition toward bulk-driven mechanisms. - Abstract: Low energy irradiation of GaSb surfaces has been shown to lead to nanopillar formation. Being performed ex-situ, controlling the parameters of the ion beam for controlled nanopattern formation is challenging. While mainly utilized for imaging and cutting purposes, the development of multibeam (helium/neon) ion microscopes has opened the path towards the use of these microscopes for in-situ ion irradiation and nanopatterning studies. In this study, in-situ irradiation (neon ions)/imaging (helium ions) of GaSb surfaces is performed using Carl Zeiss-neon ion microscope at low energies (5 and 10 keV). Imaging with helium ions, nanodots were shown to form at particular fluences after which are smoothed. Ex-situ imaging with SEM showed nanopore formation of size controlled by the ion energy and fluence. Compared to lower energy ex-situ neon ion irradiation at similar fluxes, where nanopillars are formed, the results demonstrated a transition in the nanostructure type and formation mechanism as the energy is changed from 2 to 5 keV. Simulations show an increase in the ballistic diffusion and a decrease in the strength of phase separation as a function of ion energy in agreement with the suppression of nanopillar formation at higher energies. Collision cascade simulations suggest a transition toward bulk-driven mechanisms.

Effect of low-power density laser radiation on heatling of open skin wounds in rats

Energy Technology Data Exchange (ETDEWEB)

Kana, J.S.; Hutschenreiter, G.; Haina, D.; Waidelich, W.

1981-03-01

Researchers performed a study to determine whether laser radation of low-power density would affect the healing of open skin wounds in rats. The wounds were irradiated daily with a helium-neon laser and an argon laser at a constant power density of 45 mW/sq cm. The rate of wound closure was followed by photographing the wounds in a standardized way. The collagen hydroxyproline concentration in the scar tissue was determined on the 18th postoperative day. Helium-neon laser radiation had a statistically significant stimulating effect on collagen synthesis in the wound, with a maximum effect at an energy density of 4 joules/sq cm. The rate of wound closure was enhanced significantly between the third and 12th postoperative days. The argon laser exposure produced a significant increase in collagen concentration both in irradiated and nonirradiated contralateral wounds. However, an acceleration of the healing rate was not registered in this case. The wound contraction up to the fourth day of the experiment was inhibited under helium-neon and argon laser exposure to 20 joules/sq cm. The described effects were not specific for the laser light. There may be a wavelength-selective influence of coherent light on the metabolic and proliferation processes in wound healing, with the associated problem of the possible carcinogenic effects of laser radiation.

Polarizability of Helium, Neon, and Argon: New Perspectives for Gas Metrology

Science.gov (United States)

Gaiser, Christof; Fellmuth, Bernd

2018-03-01

With dielectric-constant gas thermometry, the molar polarizability of helium, neon, and argon has been determined with relative standard uncertainties of about 2 parts per million. A series of isotherms measured with the three noble gases and two different experimental setups led to this unprecedented level of uncertainty. These data are crucial for scientists in the field of gas metrology, working on pressure and temperature standards. Furthermore, with the new benchmark values for neon and argon, theoretical calculations, today about 3 orders of magnitude larger in uncertainty, can be checked and improved.

Laser treatment of otitis media in children

Energy Technology Data Exchange (ETDEWEB)

Podoynitsyna, L.F.

1984-08-01

Clinical trials were conducted with the helium-neon LG-75 laser (632.8 nm, 0.1 W/cm/sup 2/) in the management of 50 children with acute and chronic otitis media. The sessions consisted of 30 sec irradiation directed at the middle ear through the external meatus for a period of 5 days. Positive results were obtained in 45 of the patients with cessation of discharge on the 2nd or 3rd day, and return of hearing by the end of the week. The remission was not permanent in one patient with recurrent otitis media. These observations indicate that the anti-inflammatory effects of helium-neon irradiation constitute an effective treatment modality in children with otitis media. 6 references.

Vapor-liquid equilibrium prediction with pseudo-cubic equation of state for binary mixtures containing hydrogen, helium, or neon

Energy Technology Data Exchange (ETDEWEB)

Kato, M.; Tanaka, H. (Nihon Univ.,Fukushima, (Japan). Faculty of Enineering)

1990-03-01

As an equation of state of vapor-liquid equilibrium, an original pseudo-cubic equation of state was previously proposed by the authors of this report and its study is continued. In the present study, new effective critical values of hydrogen, helium and neon were determined empirically from vapor-liquid equilibrium data of literature values against their critical temperatures, critical pressures and critical volumes. The vapor-liquid equilibrium relations of binary system quantum gas mixtures were predicted combining the conventinal pseudo-cubic equation of state and the new effective critical values, and without using binary heteromolecular interaction parameter. The predicted values of hydrogen-ethylene, helium-propane and neon-oxygen systems were compared with literature values. As a result, it was indicated that the vapor-liquid relations of binary system mixtures containing hydrogen, helium and neon can be predicted with favorable accuracy combining the effective critical values and the three parameter pseudo-cubic equation of state. 37 refs., 3 figs., 4 tabs.

Effect of maize seed laser irradiation on plant photosynthetic activity

International Nuclear Information System (INIS)

Antonov, M.; Stanev, V.; Velichkov, D.; Tsonev, Ts.

1986-01-01

Investigations were made with the two hybrids, H-708 and P x -20. The seeds were irradiated by a helium-neon quantum generator (L'vov-1 Electronica) with output power of 24 MW and 632.8 nm wave length. Once and twice irradiated seeds were sown on the 2nd, 5th and 10th day post irradiation. Changes in leaf area, chlorophyll content in the leaves, photosynthetic rate and its dependence on temperature and light, transpiration, stomatal resistance to CO 2 and total dry matter of the overground plant part were traced. Seed irradiation with laser rays did not affect the chlorophyll content of the leaves. The photosynthetic rate did not depend on the cultivar characteristics of the crop. Single and repeated irradiation of the hybrid H-708 in most case enhanced photosynthetic rate, but a similar effect was not observed in P x -20. Transpiration and CO 2 stomatal resistance were not equally affected by radiation. Laser rays enhanced the ability of the photosynthetic apparatus of the entire plants to use more efficiently high light intensities. The leaf area and the total plant dry matter increased in case of sowing on the 2nd and 5th day and a single irradiation and in case of sowing on the 5th and 10th day and twice repeated irradiations

Fragmentation dynamics of ionized neon clusters (Ne(n), n=3-14) embedded in helium nanodroplets.

Science.gov (United States)

Bonhommeau, David; Halberstadt, Nadine; Viel, Alexandra

2006-01-14

We report a theoretical study of the nonadiabatic fragmentation dynamics of ionized neon clusters embedded in helium nanodroplets for cluster sizes up to n=14 atoms. The dynamics of the neon atoms is modeled using the molecular dynamics with quantum transitions method of Tully [J. Chem. Phys. 93, 1061 (1990)] with the nuclei treated classically and transitions between electronic states quantum mechanically. The potential-energy surfaces are derived from a diatomics-in-molecules model to which induced dipole-induced dipole interactions are added. The effect of the spin-orbit interaction is also discussed. The helium environment is modeled by a friction force acting on charged atoms whose speed exceeds the critical Landau velocity. The dependence of the fragment size distribution on the friction strength and on the initial nanodroplet size is investigated. By comparing with the available experimental data obtained for Ne3+ and Ne4+, a reasonable value for the friction coefficient, the only parameter of the model, is deduced. This value is then used to predict the effect of the helium environment on the dissociation dynamics of larger neon clusters, n=5-14. The results show stabilization of larger fragments than in the gas phase, but fragmentation is not completely caged. In addition, two types of dynamics are characterized for Ne4+: fast and explosive, therefore leaving no time for friction to cool down the process when dynamics starts on one of the highest electronic states, and slower, therefore leading to some stabilization by helium when it starts on one of the lowest electronic states.

Changes in Cell Viability of Wounded Fibroblasts following Laser Irradiation in Broad-Spectrum or Infrared Light

International Nuclear Information System (INIS)

Hawkins, D.; Abrahamse, H.

2007-01-01

Objective. This study aimed to establish if broad-spectrum or infrared (IR) light in combination with laser therapy can assist phototherapy to improve the cell function of wounded cells. Background. The effect of laser light may be partly or completely reduced by broad-spectrum light. Methods. Wounded human skin fibroblasts were irradiated with 5 J/cm2 using a helium-neon laser, a diode laser, or an Nd:YAG laser in the dark, in the light, or in IR. Changes in cell viability were evaluated by cell morphology, ATP cell viability, LDH membrane integrity, and caspase 3/7 as an early marker of apoptosis. Results. Wounded cells exposed to 5 J/cm2 using 632.8 nm in the dark or 830 nm in the light or 1064 nm in the dark showed an increase in ATP viability, an increase in cytokine expression, and a decrease in LDH cytotoxicity indicating that the metabolic activity of the wounded cells was stimulated. Conclusion. Wounded cells irradiated in IR light showed an undesirable thermal effect that was proportional to the duration of exposure.

The neon gas field ion source-a first characterization of neon nanomachining properties

International Nuclear Information System (INIS)

Livengood, Richard H.; Tan, Shida; Hallstein, Roy; Notte, John; McVey, Shawn; Faridur Rahman, F.H.M.

2011-01-01

At the Charged Particle Optics Conference (CPO7) in 2006, a novel trimer based helium gas field ion source (GFIS) was introduced for use in a new helium ion microscope (HIM), demonstrating the novel source performance attributes and unique imaging applications of the HIM (Hill et al., 2008 ; Livengood et al., 2008 ). Since that time there have been numerous enhancements to the HIM source and platform demonstrating resolution scaling into the sub 0.5 nm regime (Scipioni et al., 2009 ; Pickard et al., 2010 ). At this Charged Particle Optics Conference (CPO8) we will be introducing a neon version of the trimer-GFIS co-developed by Carl Zeiss SMT and Intel Corporation. The neon source was developed as a possible supplement to the gallium liquid metal ion source (LMIS) used today in most focused ion beam (FIB) systems (Abramo et al., 1994 ; Young et al.,1998 ). The neon GFIS source has low energy spread (∼1 eV) and a small virtual source size (sub-nanometer), similar to that of the helium GFIS. However neon does differ from the helium GFIS in two significant ways: neon ions have high sputtering yields (e.g. 1 Si atom per incident ion at 20 keV); and have relatively shallow implant depth (e.g. 46 nm in silicon at 20 keV). Both of these are limiting factors for helium in many nanomachining applications. In this paper we will present both simulation and experimental results of the neon GFIS used for imaging and nanomachining applications.

Modification of genetic effects of gamma radiation by laser radiation

International Nuclear Information System (INIS)

Khotyljova, L.V.; Khokhlova, S.A.; Khokhlov, I.V.

1988-01-01

Full text: Mutants obtained by means of ionizing radiation and chemical mutagens often show low viability and productivity that makes their use in plant breeding difficult. Methods reducing the destructive mutagen action on important functions of plant organism and increasing quality and practical value of induced mutants would be interesting. We believe that one method for increasing efficiency of experimental mutagenesis in plants is the application of laser radiation as a modificator of genetic effects of ionizing radiation and chemical mutagens. Combined exposure of wheat seedlings to a gamma radiation dose of 2 kR and to laser radiation with the wave length of 632.8 nm (power density - 20 mVt/cm 2 , exposure - 30 min.) resulted in reducing the chromosomal aberration percentage from 30.5% in the gamma version to 16.3% in the combined treatment version. A radiosensibilizing effect was observed at additional exposure of gamma irradiated wheat seeds to laser light with the wave length of 441.6 nm where chromosomal aberration percentage increased from 22% in the gamma-irradiation version to 31% in the combined treatment version. By laser radiation it is also possible to normalize mitotic cell activity suppressed by gamma irradiation. Additional seedling irradiation with the light of helium-neon laser (632.8 nm) resulted in recovery of mitotic cell activity from 21% to 62% and increasing the average content of DNA per nucleus by 10%. The influence of only laser radiation on plant variability was also studied and it was shown that irradiation of wheat seeds and seedlings with pulsed and continuous laser light of visible spectrum resulted in phenotypically altered forms in M 2 . Their frequencies was dependent upon power density, dose and radiation wave length. Number of altered forms increased in going from long-wave to short-wave spectrum region. In comparing efficiency of different laser types of pulsed and continuous exposure (dose - 180 J/cm 2 ) 2% of altered

Cell and tissue kinetics of the subependymal layer in mouse brain following heavy charged particle irradiation

International Nuclear Information System (INIS)

Manley, N.B.

1988-01-01

The following studies investigate the cellular response and cell population kinetics of the subependymal layer in the mouse brain exposed to heavy charged particle irradiation. Partial brain irradiation with helium and neon ions was confined to one cortex of the brain. Both the irradiated and the unirradiated contralateral cortex showed similar disturbances of the cell and tissue kinetics in the subependymal layers. The irradiated hemisphere exhibited histological damage, whereas the unirradiated side appeared normal histologically. The decrease in the values of the labeling indices 1 week after charged particle irradiation was dose- and ion-dependent. Mitotic indices 1 week after 10 and 25 Gy helium and after 10 Gy neon were the same as those seen in the control mice. Analysis of cell kinetics 1 week after 10 Gy helium and 10 Gy neon irradiation suggests the presence of a progenitor subpopulation that is proliferating with a shorter cell cycle. Comparison of the responses to the different charged particle beams indicates that neon ions are more effective in producing direct cellular damage than the helium ions, but the surviving proliferating cells several divisions later continue to maintain active cell renewal. Based on the 1 week post-irradiation H 3 -TdR labeling indices, a rough estimate of the RBE for neon ions is at least 2.5 when compared to helium ions

Prompt ignition of a unipolar arc on helium irradiated tungsten

International Nuclear Information System (INIS)

Kajita, Shin; Takamura, Shuichi; Ohno, Noriyasu

2009-01-01

A fibreform nanostructured layer is formed on a tungsten surface by helium plasma bombardment. The helium fluence was of the order of 10 26 m -2 , and the surface temperature and incident ion energy during helium irradiation were, respectively, 1900 K and 75 eV. By irradiating a laser pulse to the surface in the plasma, a unipolar arc, which many people have tried to verify in well-defined experiments, is promptly initiated and continued for a much longer time than the laser pulse width. The laser pulse width (∼0.6 ms) and power (∼5 MJ m -2 ) are similar to the heat load accompanied by type-I edge localized modes (ELMs) in ITER. The unipolar arc is verified from an increase in the floating potential, a moving arc spot detected by a fast camera and arcing traces on the surface. This result suggests that the nanostructure on the tungsten surface formed by the bombardment of helium, which is a fusion product, could significantly change the ignition property of arcing, and ELMs become a trigger of unipolar arcing, which would be a great impurity source in fusion devices. (letter)

First principles study of inert-gas (helium, neon, and argon) interactions with hydrogen in tungsten

Energy Technology Data Exchange (ETDEWEB)

Kong, Xiang-Shan [Key Laboratory of Materials Physics, Institute of Solid State Physics, Chinese Academy of Sciences, P. O. Box 1129, Hefei 230031 (China); Hou, Jie [Key Laboratory of Materials Physics, Institute of Solid State Physics, Chinese Academy of Sciences, P. O. Box 1129, Hefei 230031 (China); University of Science and Technology of China, Hefei 230026 (China); Li, Xiang-Yan [Key Laboratory of Materials Physics, Institute of Solid State Physics, Chinese Academy of Sciences, P. O. Box 1129, Hefei 230031 (China); Wu, Xuebang, E-mail: xbwu@issp.ac.cn [Key Laboratory of Materials Physics, Institute of Solid State Physics, Chinese Academy of Sciences, P. O. Box 1129, Hefei 230031 (China); Liu, C.S., E-mail: csliu@issp.ac.cn [Key Laboratory of Materials Physics, Institute of Solid State Physics, Chinese Academy of Sciences, P. O. Box 1129, Hefei 230031 (China); Chen, Jun-Ling; Luo, G.-N. [Institute of Plasma Physics, Chinese Academy of Sciences, Hefei 230031 (China)

2017-04-15

We have systematically evaluated binding energies of hydrogen with inert-gas (helium, neon, and argon) defects, including interstitial clusters and vacancy-inert-gas complexes, and their stable configurations using first-principles calculations. Our calculations show that these inert-gas defects have large positive binding energies with hydrogen, 0.4–1.1 eV, 0.7–1.0 eV, and 0.6–0.8 eV for helium, neon, and argon, respectively. This indicates that these inert-gas defects can act as traps for hydrogen in tungsten, and impede or interrupt the diffusion of hydrogen in tungsten, which supports the discussion on the influence of inert-gas on hydrogen retention in recent experimental literature. The interaction between these inert-gas defects and hydrogen can be understood by the attractive interaction due to the distortion of the lattice structure induced by inert-gas defects, the intrinsic repulsive interaction between inert-gas atoms and hydrogen, and the hydrogen-hydrogen repelling in tungsten lattice.

Disalignment rate coefficient of neon excited atoms due to helium atom collisions at low temperatures

International Nuclear Information System (INIS)

Seo, M; Shimamura, T; Furutani, T; Hasuo, M; Bahrim, C; Fujimoto, T

2003-01-01

Disalignment of neon excited atoms in the fine-structure 2p i levels (in Paschen notation) of the 2p 5 3p configuration is investigated in a helium-neon glow discharge at temperatures between 15 and 77 K. At several temperatures, we plot the disalignment rate as a function of the helium atom density for Ne* (2p 2 or 2p 7 ) + He(1s 2 ) collisions. The slope of this dependence gives the disalignment rate coefficient. For both collisions, the experimental data for the disalignment rate coefficient show a more rapid decrease with the decrease in temperature below 40 K than our quantum close-coupling calculations based on the model potential of Hennecart and Masnou-Seeuws (1985 J. Phys. B: At. Mol. Phys. 18 657). This finding suggests that the disalignment cross section rapidly decreases below a few millielectronvolts, in disagreement with our theoretical quantum calculations which predict a strong increase below 1 meV. The disagreement suggests that the long-range electrostatic potentials are significantly more repulsive than in the aforementioned model

Solar helium and neon in the Earth

Science.gov (United States)

Honda, M.; Mcdougall, I.; Patterson, D. B.

1994-01-01

Neon isotopic compositions in mantle-derived samples commonly are enriched in (20)Ne and (21)Ne relative to (22)Ne compared with atmospheric neon ((20)Ne/(22)Ne and (21)Ne/(22)Ne ratios in atmospheric neon are 9.8 and 0.029, respectively), together with significant primordial (3)He. Such results have been obtained on MORB's, intraplate plume-related oceanic island basalts, backarc basin basalts, mantle xenoliths, ancient diamonds and CO2 well gases (e.g., 1 - 8). The highest (20)Ne/(22)Ne ratio observed in MORB glasses (= 13.6 plus or minus 1.3 is close to the solar value (= 13.6, as observed in solar wind). In order to explain the enrichment of (20)Ne and (21)Ne relative to atmospheric neon for samples derived from the mantle, it is necessary to postulate the presence of at least two distinct non-atmospheric components. The two most likely candidates are solar and nucleogenic ((20)Ne/(22)Ne solar = 13.6 (21)Ne/(22)Ne solar = 0.032, (20)Ne/(22)Ne nucleogenic = 2.5 and (21)Ne/(22)Ne nucleogenic = 32). This is because solar neon is the only known component with a (20)Ne/(22)Ne ratio greater than both the atmospheric value and that observed in samples derived from the mantle. Nucleogenic neon is well known to elevate (21)Ne/(22)Ne ratios. Neon isotopic signatures observed in mantle-derived samples can be accounted for by mixing of the three neon end members: solar, nucleogenic and atmospheric.

Some characteristics of the digitization pulses from high pressure neon-helium flash tubes

International Nuclear Information System (INIS)

Chan, D.S.K.; Leung, S.K.; Ng, L.K.

1979-01-01

Characteristics of the digitization output pulses from high pressure neon-helium flash tubes were studied under various operation conditions using square ultra-high voltage pulses. Properties reported by previous workers were compared. Two discharge mechanisms, the Townsend avalanche discharge and the streamer discharge, were observed to occur in sequence in some events. The output waveforms for both discharge mechanisms were studied in detail. The charge induced on a detecting probe was also estimated from the measured data. (Auth.)

Photo-stimulatory effect of low energy helium-neon laser irradiation on excisional diabetic wound healing dynamics in wistar rats

Directory of Open Access Journals (Sweden)

Maiya Arun

2009-01-01

Full Text Available Background: Generally, the significances of laser photo stimulation are now accepted, but the laser light facilitates wound healing and tissue repair remains poorly understood. Aims: We have examined the hypothesis that the laser photo stimulation can enhance the collagen production in diabetic wounds using the excision wound model in the Wistar rat model. Methods: The circular wounds were created on the dorsum of the back of the animals. The animals were divided into two groups. The study group (N = 24 wound was treated with 632.8 nm He-Ne laser at a dose of 3-9J/cm 2 for 5 days a week until the wounds healed completely. The control group was sham irradiated. Result: A significant increase in the hydroxyproline content and reduction in the wound size were observed in the study group. The pro-healing actions seem to be due to increased collagen deposition as well as better alignment and maturation. Conclusion: The biochemical analysis and clinical observation suggested that 3-6 J/cm 2 laser photo stimulation facilitates the tissue repair process by accelerating collagen production in diabetic wound healing.

Polarization transfer between oriented metastable helium atoms and neon atoms. A comparison of even and odd isotopes

Energy Technology Data Exchange (ETDEWEB)

Pepper, D M; Wang, H T.M.

1983-11-01

Collision-induced polarization transfer from optically pumped helium to excited states of neon is studied using various combinations of even and odd isotopes. It is found that, within our experimental accuracy of 10%, the resultant polarization is independent of the isotopic composition of the binary mixture. Possible applications using this mechanism are discussed.

Laser optogalvanic wavelength calibration with a commercial hollow cathode iron - neon discharge lamp

Science.gov (United States)

Zhu, Xinming; Nur, Abdullahi H.; Misra, Prabhakar

1994-01-01

351 optogalvanic transitions have been observed in the 337 - 598 nm wavelength region using an iron - neon hollow cathode discharge lamp and a pulsed tunable dye laser. 223 of these have been identified as transitions associated with neon energy levels. These optogalvanic transitions have allowed, in conjunction with interference fringes recorded concomitantly with an etalon, the calibration of the dye laser wavelength with 0.3/cm accuracy.

Numerical investigation of depth profiling capabilities of helium and neon ions in ion microscopy

Directory of Open Access Journals (Sweden)

Patrick Philipp

2016-11-01

Full Text Available The analysis of polymers by secondary ion mass spectrometry (SIMS has been a topic of interest for many years. In recent years, the primary ion species evolved from heavy monatomic ions to cluster and massive cluster primary ions in order to preserve a maximum of organic information. The progress in less-damaging sputtering goes along with a loss in lateral resolution for 2D and 3D imaging. By contrast the development of a mass spectrometer as an add-on tool for the helium ion microscope (HIM, which uses finely focussed He+ or Ne+ beams, allows for the analysis of secondary ions and small secondary cluster ions with unprecedented lateral resolution. Irradiation induced damage and depth profiling capabilities obtained with these light rare gas species have been far less investigated than ion species used classically in SIMS. In this paper we simulated the sputtering of multi-layered polymer samples using the BCA (binary collision approximation code SD_TRIM_SP to study preferential sputtering and atomic mixing in such samples up to a fluence of 1018 ions/cm2. Results show that helium primary ions are completely inappropriate for depth profiling applications with this kind of sample materials while results for neon are similar to argon. The latter is commonly used as primary ion species in SIMS. For the two heavier species, layers separated by 10 nm can be distinguished for impact energies of a few keV. These results are encouraging for 3D imaging applications where lateral and depth information are of importance.

Ab initio calculation of the interaction potentials of helium, neon, and methane as well as theoretical studies on their thermophysical properties and those of water vapor; Ab initio-Berechnung der Wechselwirkungspotentiale von Helium, Neon und Methan sowie theoretische Untersuchungen zu ihren thermophysikalischen Eigenschaften und denen von Wasserdampf

Energy Technology Data Exchange (ETDEWEB)

Hellmann, Robert

2009-06-16

Thermophysical properties of the pure gases helium, neon, methane and water vapor were calculated for low densities over wide temperature ranges. Statistical thermodynamics was used for the determination of the pressure virial coefficients. The kinetic theory of gases was utilized for the calculation of the transport and relaxation properties. So far kinetic theory was limited to linear molecules and has now been extended to molecules of arbitrary geometry to enable calculations on methane and water vapor. The interaction potentials, which are needed for all computations, were determined for helium, neon and methane from the supermolecular approach using quantum chemical ab initio methods. For water the interaction potentials were taken from the literature. The calculated values of the thermophysical properties for the four gases show very good agreement with the best experimental data. At very low and very high temperatures the theoretical values are more accurate than experimental data. (orig.)

Low-power-laser therapy used in tendon damage

Science.gov (United States)

Strupinska, Ewa

1996-03-01

The following paper covers evaluation of low-power laser therapy results in chronic Achilles tendon damage and external Epicondylalia (tennis elbow). Fifty patients with Achilles damage (18 women and 32 men, age average 30, 24 plus or minus 10, 39 years) and fifty patients having external Epicondyalgiae (31 women and 19 men, age average 44, 36 plus or minus 10, 88 years) have been examined. The patients were irradiated by semiconductor infrared laser wavelength 904 nm separately or together with helium-neon laser wavelength 632.8 nm. The results of therapy have been based on the patient's interviews and examinations of patients as well as on the Laitinen pain questionnaire. The results prove analgesic effects in usage of low- power laser radiation therapy can be obtained.

Effects of ionizing radiation on the light sensing elements of the retina. [Structural and physiological effects of carbon, helium, and neon ions on rods and cones of salamanders and mice

Energy Technology Data Exchange (ETDEWEB)

Malachowski, M.J.

1978-07-01

This investigation was undertaken to quantitate possible morphological and physiological effects of particles of high linear energy transfer on the retina, in comparison with x-ray effects. The particles used were accelerated atomic nuclei of helium, carbon, and neon at kinetic energies of several hundred MeV/nucleon. For morphological studies, scanning and transmission electron microscopy and light microscopy were used. Physiological studies consisted of autoradiographic data of the rate of incorporation of labeled protein in the structures (opsin) of the outer segment of visual cells. Structural changes were found in the nuclei, as well as the inner and outer segments of visual cells, rods and cones. At a low dose of 10 rad, x rays and helium had no statistically significant morphological effects, but carbon and neon beams did cause significant degeneration of individual cells, pointing to the existence of a linear dose--effect relationship. At high doses of several hundred rads, a Pathologic Index determined the relative biological effectiveness of neon against alpha particles to have a value of greater than 6. The severity of effects per particle increased with atomic number. Labeling studies demonstrated a decreased rate of incorporation of labeled proteins in the structural organization of the outer segments of visual rods. The rate of self-renewal of visual rod discs was punctuated by irradiation and the structures themselves were depleted of amino acids. A model of rod discs (metabolic and catabolic) was postulated for correlated early and late effects to high and low doses.

The effect of green helium-neon laser on the healing of extraction wounds: histological study in rats

International Nuclear Information System (INIS)

Nicolli Filho, Walter Domingos; Picon, Luciana Christofolini; Okamoto, Tetuo; Cardenuto, Ney

1993-01-01

A histological study on healing of extraction wounds following laser irradiation, using a green He-Ne laser, was carried out in rats. The results suggest that this kind of treatment has no significant beneficial effect on bony wound healing. Proliferation of fibroblasts and formation of trabecular osteoid were found to be not more pro eminent within the irradiated group. (author)

Mutation breeding of Bacillus subtilis YTB4 with high yield of ...

African Journals Online (AJOL)

DR TONUKARI NYEROVWO

2012-07-17

Jul 17, 2012 ... Helium-neon (He-Ne) laser irradiation is a highly efficient mutation breeding technology and is widely applied to various fields of biological science. Using Bacillus subtilis YTB4 with high yield of multienzyme complex as original strain, mutation breeding was carried out by He-Ne laser irradiation in.

Laser and thermal bleaching of colour centres in sodium borate glasses

Energy Technology Data Exchange (ETDEWEB)

Bukharaev, A A; Yafaev, N R [AN SSSR, Kazan. Fiziko-Tekhnicheskij Inst.

1978-12-01

The maximum of the additional absorption band in ..gamma..- or UV-irradiated sodium borate glasses shifts to higher energy when the low-energy side of the band is bleached by a helium-neon laser, ..lambda.. = 632.8 nm. Simultaneously the half-width of the additional absorption band decreases. This phenomenon is associated with the fact that because of structural disorder of glasses there is a distribution of ground-state energies of trapped electrons forming the light-sensitive absorption band. The distribution interval of the activation energy for trapped electrons is estimated using the decomposition of the initial thermal bleaching curves into components. For UV irradiated glasses it is aproximately 0.24 eV, and for ..gamma..-irradiated glasses only 0.12 eV. These values correlate with the relative shift maximum of the absorption band at laser bleaching.

Mutation breeding of Bacillus subtilis YTB4 with high yield of ...

African Journals Online (AJOL)

Helium-neon (He-Ne) laser irradiation is a highly efficient mutation breeding technology and is widely applied to various fields of biological science. Using Bacillus subtilis YTB4 with high yield of multienzyme complex as original strain, mutation breeding was carried out by He-Ne laser irradiation in this study. Based on the ...

Opacity test using a neon-seeded theta pinch

International Nuclear Information System (INIS)

Thomson, D.B.

1980-02-01

Vacuum ultraviolet (VUV) emission from a neon-seeded high-density theta-pinch has been observed for comparison with theoretical radiation emission calculations. The plasma was created in a 25-cm-long theta-coil with 90-kG field having a 3.0-μs quarter period. A gas fill of 1 torr of helium + 2% neon was used. Observation of the HeII 4686 line/continuum ratio gave an electron temperature of 25 +- 4 eV. Shadowgraphs of the plasma radius, taken with a ruby laser, gave an electron density of 0.9 +- 0.09 x 10 18 cm -3 . The VUV emission was observed in radial view and with time resolution with a 2.2-m grazing-incidence monochromator equipped with a photomultiplier and p-terphenyl scintillator. Thin foils of carbon and aluminum were used as filters to absorb stray light and pass emission in the 44- to 100-A region

Influence of the He-Ne laser in different irradiation regimes on the cornea cells after ionizing irradiation

International Nuclear Information System (INIS)

Bulyakova, N.V.

1984-01-01

A study was made on epithelium cells of the eye cornea in mices entering the first postradiation mitosis. The influence of laser rays acting in the course of each exposure during one and the same period of time, or continuously, or by pulses was compared. The effect of laser radiation was evaluated from the frequency of occurrence of cells with chromosomal aberrations, mitotic index, coefficient of mitosis phases. It has been established that pulse radiation of a helium-neon laser in a certain operation regime produces a sanitating effect on cells of eye cornea epithelium in white mice damaged by ionizing radiation. Cells being killed in the interphase were not revealed in epithelium of the eye cornea. It enables to conclude that the amount of aberrant mitoses decreases as a result of postradiation repair of cells damaged by ionizing radiation, but not as a result of their elimination

Biological behaviour of cucumbers depending on rhythm of seed irradiation with laser beam

International Nuclear Information System (INIS)

Cholakov, D.

1997-01-01

The aim of the study was to determine the optimal parameters of laser stimulation and obtained as a result resonance activation of phytohormones responsible for growth and formation of generative organs. The influence of the rhythm of irradiation on its effect was investigated. Cucumber seeds from the Bulgarian salad cultivar Gergana were irradiated with helium-neon laser of 632.8 nm wave length and exit power 20 mw. Besides control samples, the following irradiation groups were examined: 7-times on the 28th day before sowing (variant 7); 7-times in rhythm - 4-times on the 28th and 3-times on the 14th day before sowing (4+3); 7-times in rhythm - 3-times on the 28th and 3-times on the 14th and once on the day before sowing (3+3+1); 7-times in rhythm - 2-times on the 28th, the 21st and the 14th day and once on the day before sowing (2+2+2+1); 7-times in rhythm - once on the 28th, 24th, 20th, 16th, 12th, 8th and 4th day before sowing (1+1+1+1+1+1+1). There was the highest radiobiological effect at the rhythm of irradiation (2+2+2+1) and (1+1+1+1+1+1+1). The rhythmical application of radiation dose ensures better accumulation of the polarized light by the plant cells. The change of their electric vectors accelerates their growth and forces the physiological and biochemical processes. As a result the early yield has been increased respectively by 15.6% and 12% and the total standard yield - by 15.4% and 11.7%

Effect of helium irradiation on fracture modes

International Nuclear Information System (INIS)

Hanamura, T.; Jesser, W.A.

1982-01-01

The objective of this work is to determine the crack opening mode during in-situ HVEM tensile testing and how it is influenced by test temperature and helium irradiation. Most cracks were mixed mode I and II. However, between 250 0 C and room temperature the effect of helium irradiation is to increase the amount of mode I crack propagation. Mode II crack opening was observed as grain boundary sliding initiated by a predominantly mode I crack steeply intersecting the grain boundary. Mode II crack opening was absent in irradiated specimens tested between 250 0 C and room temperature, but could be restored by a post irradiation anneal

Thermal release behavior of helium from copper irradiated by He+ ions

International Nuclear Information System (INIS)

Yamauchi, T.; Tokura, S.; Yamanaka, S.; Miyake, M.

1988-01-01

Thermal release behavior of helium from copper irradiated by 20 keV He + ions with a dose of 2x10 15 to 3x10 17 ions/cm 2 has been studied. The shape of the thermal release curves and thew number of helium release peaks strongly depend on the irradiation dose. Results from SEM surface observastion after post-irradiation heating suggested that helium release caused various surface damages such as blistering, flaking, and hole formation. Helium release resulting in small holes was analyzed and helium bubble growth mechanisms are discussed. (orig.)

Studies on acute toxic effects to keratinocytes induced by hematoporphyrin derivatives and laser light.

Science.gov (United States)

Artuc, M; Ramshad, M; Kappus, H

1989-01-01

Human epidermal keratinocytes were grown in culture and the uptake of hematoporphyrin derivatives (HPDs) used in photodynamic therapy was estimated. Keratinocytes loaded with HPDs were irradiated with laser light of 632 nm generated by a helium-neon laser and cell toxicity was determined by the trypan blue exclusion test and the measurement of enzyme release. With increasing intracellular concentration of HPDs and with increasing intensity of the laser light, an increasing number of cells took up trypan blue and released the cytosolic enzyme lactate dehydrogenase and the lysosomal enzyme acid phosphatase after 1 h incubation of the irradiated cells at 37 degrees C. Cytotoxicity was less pronounced when the irradiated cells were incubated at 0 degree C indicating the involvement of enzyme reactions in cell death. No lipid peroxidation as measured by malondialdehyde and ethane formation was detectable. Our results suggest that during photodynamic therapy with HPDs and laser light epidermal keratinocytes may be seriously damaged. The data indicate that not lipid peroxidation but rather the activation of lysosomal enzymes is responsible for the cytotoxicity observed.

Hydrogen retention properties of polycrystalline tungsten and helium irradiated tungsten

International Nuclear Information System (INIS)

Hino, T.; Koyama, K.; Yamauchi, Y.; Hirohata, Y.

1998-01-01

The hydrogen retention properties of a polycrystalline tungsten and tungsten irradiated by helium ions with an energy of 5 keV were examined by using an ECR ion irradiation apparatus and a technique of thermal desorption spectroscopy, TDS. The polycrystalline tungsten was irradiated at RT with energetic hydrogen ions, with a flux of 10 15 H cm -2 and an energy of 1.7 keV up to a fluence of 5 x 10 18 H cm -2 . Subsequently, the amount of retained hydrogen was measured by TDS. The heating temperature was increased from RT to 1000 C, and the heating rate was 50 C min -1 . Below 1000 C, two distinct hydrogen desorption peaks were observed at 200 C and 400 C. The retained amount of hydrogen was observed to be five times smaller than that of graphite, but the concentration in the implantation layer was comparable with that of graphite. Also, the polycrystalline tungsten was irradiated with 5 keV helium ions up to a fluence of 1.4 x 10 18 He cm -2 , and then re-irradiated with 1.7 keV hydrogen ions. The amount of retained hydrogen in this later experiment was close to the value in the case without prior helium ion irradiation. However, the amount of hydrogen which desorbed around the low temperature peak, 200 C, was largely enhanced. The desorption amount at 200 C saturated for the helium fluence of more than 5 x 10 17 He cm -2 . The present data shows that the trapping state of hydrogen is largely changed by the helium ion irradiation. Additionally, 5 keV helium ion irradiation was conducted on a sample pre-implanted with hydrogen ions to simulate a helium ion impact desorption of hydrogen retained in tungsten. The amount of the hydrogen was reduced as much as 50%. (orig.)

Helium retention in krypton ion pre-irradiated nanochannel W film

Science.gov (United States)

Qin, Wenjing; Ren, Feng; Zhang, Jian; Dong, Xiaonan; Feng, Yongjin; Wang, Hui; Tang, Jun; Cai, Guangxu; Wang, Yongqiang; Jiang, Changzhong

2018-02-01

Nanochannel tungsten (W) film is a promising candidate as an alternative to bulk W for use in fusion applications. In previous work it has been shown to have good radiation resistance under helium (He) irradiation. To further understand the influence of the irradiation-induced displacement cascade damage on helium retention behaviour in a fusion environment, in this work, nanochannel W film and bulk W were pre-irradiated by 800 keV Kr2+ ions to the fluence of 2.6  ×  1015 ions cm-2 and subsequently irradiated by 40 keV He+ ions to the fluence of 5  ×  1017 ions cm-2. The Kr2+ ion pre-irradiation greatly increases helium retention in the form of small clusters and retards the formation of large clusters. It can effectively inhibit surface helium blistering under high temperature annealing. Compared with bulk W, no cracks were found in the nanochannel W film post-irradiated by He+ ions at high fluence. The release of helium from the nanochannel W film is more than one order of magnitude higher than that of bulk W whether they are irradiated by single He+ ions or sequentially irradiated by Kr2+ and He+ ions. Moreover, swelling of the bulk W is more serious than that of the nanochannel film. Therefore, nanochannel W film has a higher radiation tolerance performance in the synergistic irradiation.

Helium release from neutron-irradiated Li{sub 2}O single crystals

Energy Technology Data Exchange (ETDEWEB)

Yamaki, Daiju; Tanifuji, Takaaki; Noda, Kenji [Japan Atomic Energy Research Inst., Tokai, Ibaraki (Japan). Tokai Research Establishment

1998-03-01

Helium release behavior in post-irradiation heating tests was investigated for Li{sub 2}O single crystals which had been irradiated with thermal neutrons in JRR-4 and JRR-2, and fast neutrons in FFTF. It is clarified that the helium release curves from JRR-4 and JRR-2 specimens consists of only one broad peak. From the dependence of the peak temperatures on the neutron fluence and the crystal diameter, and the comparison with the results obtained for sintered pellets, it is considered that the helium generated in the specimen is released through the process of bulk diffusion with trapping by irradiation defects such as some defect clusters. For the helium release from FFTF specimens, two broad peaks were observed in the release curves. It is considered to suggest that two different diffusion paths exist for helium migration in the specimen, that is, bulk diffusion and diffusion through the micro-crack due to the heavy irradiation. In addition, helium bubble formation after irradiation due to the high temperature over 800K is suggested. (J.P.N.)

Ab initio calculation of the interaction potentials of helium, neon, and methane as well as theoretical studies on their thermophysical properties and those of water vapor

International Nuclear Information System (INIS)

Hellmann, Robert

2009-01-01

Thermophysical properties of the pure gases helium, neon, methane and water vapor were calculated for low densities over wide temperature ranges. Statistical thermodynamics was used for the determination of the pressure virial coefficients. The kinetic theory of gases was utilized for the calculation of the transport and relaxation properties. So far kinetic theory was limited to linear molecules and has now been extended to molecules of arbitrary geometry to enable calculations on methane and water vapor. The interaction potentials, which are needed for all computations, were determined for helium, neon and methane from the supermolecular approach using quantum chemical ab initio methods. For water the interaction potentials were taken from the literature. The calculated values of the thermophysical properties for the four gases show very good agreement with the best experimental data. At very low and very high temperatures the theoretical values are more accurate than experimental data. (orig.)

Fission neutron irradiation of copper containing implanted and transmutation produced helium

DEFF Research Database (Denmark)

Singh, B.N.; Horsewell, A.; Eldrup, Morten Mostgaard

1992-01-01

High purity copper containing approximately 100 appm helium was produced in two ways. In the first, helium was implanted by cyclotron at Harwell at 323 K. In the second method, helium was produced as a transmutation product in 800 MeV proton irradiation at Los Alamos, also at 323 K. The distribut......High purity copper containing approximately 100 appm helium was produced in two ways. In the first, helium was implanted by cyclotron at Harwell at 323 K. In the second method, helium was produced as a transmutation product in 800 MeV proton irradiation at Los Alamos, also at 323 K...... as well as the effect of the presence of other transmutation produced impurity atoms in the 800 MeV proton irradiated copper will be discussed....

Nucleation path of helium bubbles in metals during irradiation

International Nuclear Information System (INIS)

Morishita, Kazunori

2008-01-01

Thermodynamical formalization is made for description of the nucleation and growth of helium bubbles in metals during irradiation. The proposed formalization is available or evaluating both microstructural changes in fusion first wall materials where helium is produced by (n, α) nuclear transmutation reactions, and those in fusion divertor materials where helium particles with low energy are directly implanted. Calculated nucleation barrier is significantly reduced by the presence of helium, showing that a helium bubble with an appropriate number of helium atoms depending on bubble size can nucleate without any large nucleation barriers, even at a condition where an empty void has very large nucleation barrier without helium. With the proposed thermodynamical formalization, the nucleation and growth process of helium bubbles in iron during irradiation is simulated by the kinetic Monte-Carlo (KMC) technique. It shows the nucleation path of a helium bubble on the (N He , N V ) space as functions of temperatures and the concentration of helium in the matrix, where N He and N V are the number of helium atoms and vacancies in the helium bubble, respectively. Bubble growth rates depend on the nucleation path and suggest that two different mechanisms operate for bubble growth: one is controlled by vacancy diffusion and the other is controlled by interstitial helium diffusion. (author)

Double photoionization: 2. Analysis of experimental triple differential cross sections in helium and neon

International Nuclear Information System (INIS)

Malegat, L.; Selles, P.; Mazeau, J.; Huetz, A.; Lablanquie, P.

1997-01-01

We use the general formalism established in the companion paper 1 to analyse recent measurements of the triple differential cross sections for double photoionization of He and Ne, for equal energy sharing and for 1 S e symmetry of the residual ion. A dynamical factor, which depends on the energy and on the mutual angle between the two electrons, is extracted from the experiments without relying on nay dynamical approximation. This factor is expanded with respect to the one-electron angular momentum l, up to a maximum value l max , which measures the degree of angular correlation attained by the electron pair. We discuss the physical meaning of l max , and the dependence of the dynamical factor on the target, which is observed when comparing helium and neon results. (author)

Impact of neutron irradiation on thermal helium desorption from iron

Energy Technology Data Exchange (ETDEWEB)

Hu, Xunxiang, E-mail: hux1@ornl.gov [Oak Ridge National Laboratory, Oak Ridge, TN 37831 (United States); Field, Kevin G. [Oak Ridge National Laboratory, Oak Ridge, TN 37831 (United States); Taller, Stephen [University of Michigan, Ann Arbor, MI 48109 (United States); Katoh, Yutai [Oak Ridge National Laboratory, Oak Ridge, TN 37831 (United States); Wirth, Brian D. [Oak Ridge National Laboratory, Oak Ridge, TN 37831 (United States); University of Tennessee, Knoxville, TN 37996 (United States)

2017-06-15

The synergistic effect of neutron irradiation and transmutant helium production is an important concern for the application of iron-based alloys as structural materials in fission and fusion reactors. In this study, we investigated the impact of neutron irradiation on thermal helium desorption behavior in high purity iron. Single crystalline and polycrystalline iron samples were neutron irradiated in HFIR to 5 dpa at 300 °C and in BOR-60 to 16.6 dpa at 386 °C, respectively. Following neutron irradiation, 10 keV He ion implantation was performed at room temperature on both samples to a fluence of 7 × 10{sup 18} He/m{sup 2}. Thermal desorption spectrometry (TDS) was conducted to assess the helium diffusion and clustering kinetics by analyzing the desorption spectra. The comparison of He desorption spectra between unirradiated and neutron irradiated samples showed that the major He desorption peaks shift to higher temperatures for the neutron-irradiated iron samples, implying that strong trapping sites for He were produced during neutron irradiation, which appeared to be nm-sized cavities through TEM examination. The underlying mechanisms controlling the helium trapping and desorption behavior were deduced by assessing changes in the microstructure, as characterized by TEM, of the neutron irradiated samples before and after TDS measurements.

Re-weldability tests of irradiated 316L(N) stainless steel using laser welding technique

International Nuclear Information System (INIS)

Yamada, Hirokazu; Kawamura, Hiroshi; Tsuchiya, Kunihiko; Kalinin, George; Kohno, Wataru; Morishima, Yasuo

2002-01-01

SS316L(N)-IG is the candidate material for the in-vessel and ex-vessel components of fusion reactors such as ITER (International Thermonuclear Experimental Reactor). This paper describes a study on re-weldability of un-irradiated and/or irradiated SS316L(N)-IG and the effect of helium generation on the mechanical properties of the weld joint. The laser welding process is used for re-welding of the water cooling branch pipeline repairs. It is clarified that re-welding of SS316L(N)-IG irradiated up to about 0.2 dpa (3.3 appm He) can be carried out without a serious deterioration of tensile properties due to helium accumulation. Therefore, repair of the ITER blanket cooling pipes can be performed by the laser welding process

Re-weldability tests of irradiated 316L(N) stainless steel using laser welding technique

Science.gov (United States)

Yamada, Hirokazu; Kawamura, Hiroshi; Tsuchiya, Kunihiko; Kalinin, George; Kohno, Wataru; Morishima, Yasuo

2002-12-01

SS316L(N)-IG is the candidate material for the in-vessel and ex-vessel components of fusion reactors such as ITER (International Thermonuclear Experimental Reactor). This paper describes a study on re-weldability of un-irradiated and/or irradiated SS316L(N)-IG and the effect of helium generation on the mechanical properties of the weld joint. The laser welding process is used for re-welding of the water cooling branch pipeline repairs. It is clarified that re-welding of SS316L(N)-IG irradiated up to about 0.2 dpa (3.3 appm He) can be carried out without a serious deterioration of tensile properties due to helium accumulation. Therefore, repair of the ITER blanket cooling pipes can be performed by the laser welding process.

Laser Spectroscopy of Antiprotonic Helium Atoms

CERN Multimedia

2002-01-01

%PS205 %title\\\\ \\\\Following the discovery of metastable antiprotonic helium atoms ($\\overline{p}He^{+} $) at KEK in 1991, systematic studies of their properties were made at LEAR from 1991 to 1996. In the first two years the lifetime of $\\overline{p}He^{+}$ in liquid and gaseous helium at various temperatures and pressures was measured and the effect of foreign gases on the lifetime of these atoms was investigated. Effects were also discovered which gave the antiproton a 14\\% longer lifetime in $^4$He than in $^3$He, and resulted in important differences in the shape of the annihilation time spectra in the two isotopes.\\\\ \\\\Since 1993 laser spectroscopy of the metastable $\\overline{p}He^{+}$ atoms became the main focus of PS205. Transitions were stimulated between metastable and non-metastable states of the $\\overline{p}He^{+}$ atom by firing a pulsed dye laser beam into the helium target every time an identified metastable atom was present (Figure 1). If the laser frequency matched the transition energy, the...

Low pressure broadening and shift of the 540.06 nm line of neon

International Nuclear Information System (INIS)

Bielski, A.; Dokurno, W.; Szudy, J.; Wolnikowski, J.

1980-01-01

The collision broadening and shift of the 540.06 nm line of neon emitted from a low pressure glow discharge in pure neon and a neon-helium mixture have been measured. The values of the broadening and shift coefficients were determined and compared with the results of calculations based on the Lindholm-Foley impact theory assuming a Lennard-Jones potential. The results for pure neon demonstrate the inadequacy of the Lennard-Jones potential for the Ne-Ne interaction. (orig.)

Helium production in mixed spectrum reactor-irradiated pure elements

International Nuclear Information System (INIS)

Kneff, D.W.; Oliver, B.M.; Skowronski, R.P.

1986-01-01

The objectives of this work are to apply helium accumulation neutron dosimetry to the measurement of neutron fluences and energy spectra in mixed-spectrum fission reactors utilized for fusion materials testing, and to measure helium generation rates of materials in these irradiation environments. Helium generation measurements have been made for several Fe, Cu Ti, Nb, Cr, and Pt samples irradiated in the mixed-spectrum High Flux Isotope Reactor (HFIR) and Oak Ridge Research Reactor (ORR) at the Oak Ridge National Laboratory. The results have been used to integrally test the ENDF/B-V Gas Production File, by comparing the measurements with helium generation predictions made by Argonne National Laboratory using ENDF/B-V cross sections and adjusted reactor spectra. The comparisons indicate consistency between the helium measurements and ENDF/B-V for iron, but cross section discrepancies exist for helium production by fast neutrons in Cu, Ti, Nb, and Cr (the latter for ORR). The Fe, Cu, and Ti work updates and extends previous measurements

Helium bubbles aggravated defects production in self-irradiated copper

Science.gov (United States)

Wu, FengChao; Zhu, YinBo; Wu, Qiang; Li, XinZhu; Wang, Pei; Wu, HengAn

2017-12-01

Under the environment of high radiation, materials used in fission and fusion reactors will internally accumulate numerous lattice defects and bubbles. With extensive studies focused on bubble resolution under irradiation, the mutually effects between helium bubbles and displacement cascades in irradiated materials remain unaddressed. Therefore, the defects production and microstructure evolution under self-irradiation events in vicinity of helium bubbles are investigated by preforming large scale molecular dynamics simulations in single-crystal copper. When subjected to displacement cascades, distinguished bubble resolution categories dependent on bubble size are observed. With the existence of bubbles, radiation damage is aggravated with the increasing bubble size, represented as the promotion of point defects and dislocations. The atomic mechanisms of heterogeneous dislocation structures are attributed to different helium-vacancy cluster modes, transforming from the resolved gas trapped with vacancies to the biased absorption of vacancies by the over-pressured bubble. In both cases, helium impedes the recombination of point defects, leading to the accelerated formation of interstitial loops. The results and insight obtained here might contribute to understand the underlying mechanism of transmutant solute on the long-term evolution of irradiated materials.

Desorption of tritium and helium from high dose neutron irradiated beryllium

Science.gov (United States)

Kupriyanov, I. B.; Nikolaev, G. N.; Vlasov, V. V.; Kovalev, A. M.; Chakin, V. P.

2007-08-01

The effect of high dose neutron irradiation on tritium and helium desorption in beryllium is described. Beryllium samples were irradiated in the SM and BOR-60 reactors to a neutron fluences ( E > 0.1 MeV) of (5-16) × 10 22 cm -2 at 70-100 °C and 380-420 °C. A mass-spectrometry technique was used in out of pile tritium release experiments during stepped annealing in the 250-1300 °C temperature range. The total amount of helium accumulated in irradiated beryllium samples varied from 6000 to 7200 appm. The first signs of tritium and helium release were detected at temperature of 312-445 °C and 500-740 °C, respectively. It is shown that most tritium (˜82%) from sample irradiated at 70-100 °C releases in temperature range of 312-700 °C before the beginning of helium release (740 °C). In the case of beryllium sample irradiated at 380-420 °C, tritium release starts at a higher temperature ( Ts > Tann = 445 °C) and most of the tritium (˜99.8%) is released concurrently with helium which could be considered as evidence of co-existence of partial amounts of tritium and helium in common bubbles. Both the Be samples differ little in the upper temperatures of gas release: 745 and 775 °C for tritium; 1140 and 1160 °C for helium. Swelling of beryllium starts to play a key role in accelerating tritium release at Tann > 600 °C and in helium release - at Tann > 750 °C.

Os efeitos do laser hélio-neônio de baixa intensidade na cicatrização de lesões cutâneas induzidas em ratos Effects of low-level helium-neon laser on induced wound healing in rats

Directory of Open Access Journals (Sweden)

Viviane L. Busnardo

2010-02-01

Full Text Available OBJETIVO: Avaliar os efeitos do laser de baixa potência hélio e neônio (HeNe na cicatrização de feridas cutâneas de ratos. MÉTODOS: Sessenta ratos Wistar foram divididos em grupos controle e experimento. Utilizou-se ferida incisional, longitudinal, dorso-mediana, suturada com pontos separados simples. No grupo experimento, as feridas foram irradiadas diariamente com aparelho de laser de HeNe com potência contínua máxima de 5mW, comprimento de onda de 632,8 nm, visível com densidade de energia de 4J/cm², área de raio do laser de 0,015cm², durante 36 segundos, em três pontos da lesão. As feridas foram avaliadas no 3º, no 7º e no 14º dia de pós-operatório. Cortes histológicos foram corados com hematoxilina-eosina (H&E e avaliados segundo protocolo de Vizzotto et al. (2003* para identificar o tipo de reação inflamatória e com Picrosirius para identificar os colágenos I e III e o índice de maturidade da cicatriz (IMaC. Utilizou-se imunoistoquímica com anti-CD45-LCA para o reconhecimento das células inflamatórias. RESULTADOS: Ambos os grupos mostraram o mesmo padrão inflamatório. No grupo experimento, observaram-se menos células inflamatórias nos três tempos estudados (pOBJECTIVE: To evaluate the effects of low-level helium-neon (HeNe laser on cutaneous wound healing in rats. METHODS: Sixty Wistar rats were divided into control group and experimental group. A sutured longitudinal, dorsal-medial incision was made, with simple separate stitches. The experimental group was irradiated daily in three areas of the wound with HeNe laser (5mW maximum continuous power, 632.8 nm wavelength, 4 J/cm² energy density and 0.015 cm² laser beam area for 36 seconds. The areas were evaluated on the third, seventh and fourteenth days postoperative. Histological sections were stained with hematoxylin-eosin to determine the type of inflammatory reaction according to the protocol by Vizzotto et al. (2003* and with Picrosirius to identify

Shock Compression Response of the Light Noble Gases: Neon and Helium

Science.gov (United States)

Root, Seth; Shulenburger, Luke; Cochrane, Kyle; Lopez, Andrew; Shelton, Keegan; Villalva, Jose; Mattsson, Thomas

2015-06-01

Understanding material behavior at extreme conditions is important to a wide range of processes in planetary astrophysics and inertial confinement fusion. Modeling the high pressure - high temperature processes requires robust equations of state (EOS). For many materials, EOS models have been developed using low-pressure Hugoniot data. Assumptions are made to extrapolate the EOS models to Mbar pressure regimes, leading to different model behavior at extreme conditions. In this work, we examine the high pressure response of the light noble gases: neon and helium in the multi-Mbar regime. We perform a series of shock compression experiments using Sandia's Z-Machine on cryogenically cooled liquids of Ne (26 K) and He (2.2 K) to measure the Hugoniot and reshock states. In parallel, we use density functional theory methods to calculate the Hugoniot and reshock states. The experiments validated the DFT simulations and the combined experimental and simulation results are used to assess the EOS models. Sandia National Laboratories is a multi-program laboratory managed and operated by Sandia Corporation, a wholly owned subsidiary of Lockheed Martin Corporation, for the U.S. Department of Energy's National Nuclear Securities Administration under Contract No. DE-AC04-94AL85000.

Cellular and molecular effects for mutation induction in normal human cells irradiated with accelerated neon ions

International Nuclear Information System (INIS)

Suzuki, Masao; Tsuruoka, Chizuru; Kanai, Tatsuaki; Kato, Takeshi; Yatagai, Fumio; Watanabe, Masami

2006-01-01

We investigated the linear energy transfer (LET) dependence of mutation induction on the hypoxanthine-guanine phosphoribosyl transferase (HPRT) locus in normal human fibroblast-like cells irradiated with accelerated neon-ion beams. The cells were irradiated with neon-ion beams at various LETs ranging from 63 to 335 keV/μm. Neon-ion beams were accelerated by the Riken Ring Cyclotron at the Institute of Physical and Chemical Research in Japan. Mutation induction at the HPRT locus was detected to measure 6-thioguanine-resistant clones. The mutation spectrum of the deletion pattern of exons of mutants was analyzed using the multiplex polymerase chain reaction (PCR). The dose-response curves increased steeply up to 0.5 Gy and leveled off or decreased between 0.5 and 1.0 Gy, compared to the response to 137 Cs γ-rays. The mutation frequency increased up to 105 keV/μm and then there was a downward trend with increasing LET values. The deletion pattern of exons was non-specific. About 75-100% of the mutants produced using LETs ranging from 63 to 335 keV/μm showed all or partial deletions of exons, while among γ-ray-induced mutants 30% showed no deletions, 30% partial deletions and 40% complete deletions. These results suggested that the dose-response curves of neon-ion-induced mutations were dependent upon LET values, but the deletion pattern of DNA was not

Challenges of fabricating plasmonic and photonic structures with Neon ion beam milling

DEFF Research Database (Denmark)

Leißner, Till; Fiutowski, Jacek; Bozhevolnyi, Sergey I.

-established electron beam lithography and focussed ion beam milling (FIB) using Gallium ions. These techniques, however, are to some extend limited in their resolution, and in addition Gallium and Carbon are implanted and deposited into the plasmonic structures during FIB process, potentially changing plasmonic...... properties. We are currently studying the capabilities of focussed Helium and Neon ion beam milling for the fabricating of plasmonic and photonic devices. We found that Neon ion beam milling enables us to prepare plasmonic structures, such as trenches (see Fig. 1) and V-grooves without doping and alloying...... effects specific to Galium FIB. Neon FIB milling is superior to Helium FIB milling in terms of the processing speed and smaller levels of implanted ions. From our perspective it is the most promising technique for the fabrication of individual plasmonic devices with a few nanometers precision. The main...

Two-photon laser spectroscopy of antiprotonic helium and the antiproton-to-electron mass ratio

CERN Document Server

Hori, Masaki; Barna, Daniel; Andreas Dax,; Hayano, Ryugo; Friedreich, Susanne; Juhász, Bertalan; Pask, Thomas; Widmann, Eberhard; Horváth, Dezső; Venturelli, Luca; Zurlo, Nicola; 10.1038/nature10260

2013-01-01

Physical laws are believed to be invariant under the combined transformations of charge, parity and time reversal (CPT symmetry). This implies that an antimatter particle has exactly the same mass and absolute value of charge as its particle counterpart. Metastable antiprotonic helium ($\\bar{p}He^+$) is a three-body atom2 consisting of a normal helium nucleus, an electron in its ground state and an antiproton ($\\bar{p}$) occupying a Rydberg state with high principal and angular momentum quantum numbers, respectively n and l, such that n ≈ l + 1 ≈ 38. These atoms are amenable to precision laser spectroscopy, the results of which can in principle be used to determine the antiproton-to-electron mass ratio and to constrain the equality between the antiproton and proton charges and masses. Here we report two-photon spectroscopy of antiprotonic helium, in which $\\bar{p}^{3}He^{+}$ and $\\bar{p}^{4}He^{+}$ isotopes are irradiated by two counter-propagating laser beams. This excites nonlinear, two-phot...

Resonant photopumping of a neon lasant plasma by a sodium pump plasma

International Nuclear Information System (INIS)

Young, F.C.; Apruzese, J.P.; Burkhalter, P.G.; Cooperstein, G.; Davis, J.; Mosher, D.; Ottinger, P.F.; Scherrer, V.E.; Stephanakis, S.J.; Mehlman, C.; Welch, B.L.

1988-01-01

Resonant photopumping of heliumlike neon by helium like sodium is being investigated to extend this pumping technique to the soft x-ray region. In the Na-pump/Ne-lasant system, the 1s 2 -1s2p 1 P 1 line of Na X at 11.0027 A differs by 2 parts in 10 4 from the 1s 2 -1s 4 p 1 P 1 line of Ne 1X at 11.0003 A. This wavelength difference corresponds to about one Doppler width at the sodium plasma temperatures (200-500 eV) required for strong Na X pump radiation. Sodium line radiation of sufficient power irradiating a properly prepared neon plasma will cause overpopulation of the Ne 1X n = 4 singlet level leading to lasing in the 4-3, 4-2, and possibly 3-2 singlet transitions. Experimentally, the current pulse from the NRL Gamble-II generator is used to produce side-by-side z-pinch plasmas of sodium fluoride (NaF) and neon. The discharges are viewed radially with x-ray diagnostics including time-integrated pinhole cameras, time-resolved x-ray diodes, and a time-integrated curved-crystal spectrograph. Measurements of the neon plasma indicate that a discharge current of about 200 kA is required to produce a neon lasant with a dominant heliumlike ground-state population. For fluorescence experiments, appropriate neon lasant conditions (density of about 10 18 cm -3 and temperature of 50-100 eV) must be produced at the time of the intense sodium pump-line radiation. Fluorescence is demonstrated by observing enhancement of the 4-1 line (He-γ) from the neon plasma relative to the 3-1 line (He-γ) when the neon is pumped by sodium. An increase in this γ-to-β ratio of 25% has been observed when the sodium pump radiation is present. The results of recent experiments are reported, and their implications for future experiments are discussed

Modeling of helium bubble nucleation and growth in neutron irradiated boron doped RAFM steels

International Nuclear Information System (INIS)

Dethloff, Christian; Gaganidze, Ermile; Svetukhin, Vyacheslav V.; Aktaa, Jarir

2012-01-01

Reduced activation ferritic/martensitic (RAFM) steels are promising candidates for structural materials in future fusion technology. In addition to other irradiation defects, the transmuted helium is believed to strongly influence material hardening and embrittlement behavior. A phenomenological model based on kinetic rate equations is developed to describe homogeneous nucleation and growth of helium bubbles in neutron irradiated RAFM steels. The model is adapted to different 10 B doped EUROFER97 based heats, which already had been studied in past irradiation experiments. Simulations yield bubble size distributions, whereby effects of helium generation rate, surface energy, helium sinks and helium density are investigated. Peak bubble diameters under different conditions are compared to preliminary microstructural results on irradiated specimens. Helium induced hardening was calculated by applying the Dispersed Barrier Hardening model to simulated cluster size distributions. Quantitative microstructural investigations of unirradiated and irradiated specimens will be used to support and verify the model.

Modeling of helium bubble nucleation and growth in neutron irradiated boron doped RAFM steels

Energy Technology Data Exchange (ETDEWEB)

Dethloff, Christian, E-mail: christian.dethloff@kit.edu [Karlsruhe Institute of Technology (KIT), Institute for Applied Materials, Hermann-von-Helmholtz-Platz 1, 76344 Eggenstein-Leopoldshafen (Germany); Gaganidze, Ermile [Karlsruhe Institute of Technology (KIT), Institute for Applied Materials, Hermann-von-Helmholtz-Platz 1, 76344 Eggenstein-Leopoldshafen (Germany); Svetukhin, Vyacheslav V. [Ulyanovsk State University, Leo Tolstoy Str. 42, 432970 Ulyanovsk (Russian Federation); Aktaa, Jarir [Karlsruhe Institute of Technology (KIT), Institute for Applied Materials, Hermann-von-Helmholtz-Platz 1, 76344 Eggenstein-Leopoldshafen (Germany)

2012-07-15

Reduced activation ferritic/martensitic (RAFM) steels are promising candidates for structural materials in future fusion technology. In addition to other irradiation defects, the transmuted helium is believed to strongly influence material hardening and embrittlement behavior. A phenomenological model based on kinetic rate equations is developed to describe homogeneous nucleation and growth of helium bubbles in neutron irradiated RAFM steels. The model is adapted to different {sup 10}B doped EUROFER97 based heats, which already had been studied in past irradiation experiments. Simulations yield bubble size distributions, whereby effects of helium generation rate, surface energy, helium sinks and helium density are investigated. Peak bubble diameters under different conditions are compared to preliminary microstructural results on irradiated specimens. Helium induced hardening was calculated by applying the Dispersed Barrier Hardening model to simulated cluster size distributions. Quantitative microstructural investigations of unirradiated and irradiated specimens will be used to support and verify the model.

Damage studies on tungsten due to helium ion irradiation

International Nuclear Information System (INIS)

Dutta, N.J.; Buzarbaruah, N.; Mohanty, S.R.

2014-01-01

Highlights: • Used plasma focus helium ion source to study radiation induced damage on tungsten. • Surface analyses confirm formation of micro-crack, bubbles, blisters, pinholes, etc. • XRD patterns confirm development of compressive stress due to thermal load. • Reduction in hardness value is observed in the case of exposed sample. - Abstract: Energetic and high fluence helium ions emitted in a plasma focus device have been used successfully to study the radiation induced damage on tungsten. The reference and irradiated samples were characterized by optical microscopy, field emission scanning electron microscopy, X-ray diffraction and by hardness testers. The micrographs of the irradiated samples at lower magnification show uniform mesh of cracks of micrometer width. However at higher magnification, various types of crystalline defects such as voids, pinholes, bubbles, blisters and microcracks are distinctly noticed. The prominent peaks in X-ray diffraction spectrum of irradiated samples are seen shifted toward higher Bragg angles, thus indicating accumulation of compressive stress due to the heat load delivered by helium ions. A marginal reduction in hardness of the irradiated sample is also noticed

Helium-3 and helium-4 acceleration by high power laser pulses for hadron therapy

Directory of Open Access Journals (Sweden)

S. S. Bulanov

2015-06-01

Full Text Available The laser driven acceleration of ions is considered a promising candidate for an ion source for hadron therapy of oncological diseases. Though proton and carbon ion sources are conventionally used for therapy, other light ions can also be utilized. Whereas carbon ions require 400 MeV per nucleon to reach the same penetration depth as 250 MeV protons, helium ions require only 250 MeV per nucleon, which is the lowest energy per nucleon among the light ions (heavier than protons. This fact along with the larger biological damage to cancer cells achieved by helium ions, than that by protons, makes this species an interesting candidate for the laser driven ion source. Two mechanisms (magnetic vortex acceleration and hole-boring radiation pressure acceleration of PW-class laser driven ion acceleration from liquid and gaseous helium targets are studied with the goal of producing 250 MeV per nucleon helium ion beams that meet the hadron therapy requirements. We show that He^{3} ions, having almost the same penetration depth as He^{4} with the same energy per nucleon, require less laser power to be accelerated to the required energy for the hadron therapy.

GASP: A computer code for calculating the thermodynamic and transport properties for ten fluids: Parahydrogen, helium, neon, methane, nitrogen, carbon monoxide, oxygen, fluorine, argon, and carbon dioxide. [enthalpy, entropy, thermal conductivity, and specific heat

Science.gov (United States)

Hendricks, R. C.; Baron, A. K.; Peller, I. C.

1975-01-01

A FORTRAN IV subprogram called GASP is discussed which calculates the thermodynamic and transport properties for 10 pure fluids: parahydrogen, helium, neon, methane, nitrogen, carbon monoxide, oxygen, fluorine, argon, and carbon dioxide. The pressure range is generally from 0.1 to 400 atmospheres (to 100 atm for helium and to 1000 atm for hydrogen). The temperature ranges are from the triple point to 300 K for neon; to 500 K for carbon monoxide, oxygen, and fluorine; to 600 K for methane and nitrogen; to 1000 K for argon and carbon dioxide; to 2000 K for hydrogen; and from 6 to 500 K for helium. GASP accepts any two of pressure, temperature and density as input conditions along with pressure, and either entropy or enthalpy. The properties available in any combination as output include temperature, density, pressure, entropy, enthalpy, specific heats, sonic velocity, viscosity, thermal conductivity, and surface tension. The subprogram design is modular so that the user can choose only those subroutines necessary to the calculations.

Tensile properties and microstructure of helium-injected and reactor-irradiated V-20 Ti

International Nuclear Information System (INIS)

Tanaka, M.P.; Bloom, E.E.; Horak, J.A.

1981-01-01

Mechanical properties and microstructure of vanadium-20% titanium were examined following helium-injection and reactor irradiation. Helium was injected at ambient temperature to concentrations of 90 and 200 at. ppM; neutron irradiation was at 400, 575, 625, and 700 0 C to fluence of 3 x 10 26 n/m 2 , E > 0.1 MeV. Cavities representing negligible volume swelling were observed in all helium-injected specimens. Degradation of mechanical properties, especially loss of ductility due to helium, occurred at temperatures of 625 and 700 0 C. The levels of helium produced in the fusion spectrum can be expected to alter the response of vanadium alloys from that observed in fast reactor irradiations

Tensile properties and microstructure of helium-injected and reactor-irradiated V-20 Ti

Energy Technology Data Exchange (ETDEWEB)

Tanaka, M.P.; Bloom, E.E.; Horak, J.A.

1981-01-01

Mechanical properties and microstructure of vanadium-20% titanium were examined following helium-injection and reactor irradiation. Helium was injected at ambient temperature to concentrations of 90 and 200 at. ppM; neutron irradiation was at 400, 575, 625, and 700/sup 0/C to fluence of 3 x 10/sup 26/ n/m/sup 2/, E > 0.1 MeV. Cavities representing negligible volume swelling were observed in all helium-injected specimens. Degradation of mechanical properties, especially loss of ductility due to helium, occurred at temperatures of 625 and 700/sup 0/C. The levels of helium produced in the fusion spectrum can be expected to alter the response of vanadium alloys from that observed in fast reactor irradiations.

Binary-collision-approximation simulation for noble gas irradiation onto plasma facing materials

International Nuclear Information System (INIS)

Saito, Seiki; Nakamura, Hiroaki; Takayama, Arimichi; Ito, Atsushi M

2014-01-01

A number of experiments show that helium plasma constructs filament (fuzz) structures whose diameter is in nanometer-scale on the tungsten material under the suitable experimental condition. In this paper, binary-collision-approximation-based simulation is performed to reveal the mechanism and the conditions of fuzz formation of tungsten material under plasma irradiation. The irradiation of the plasma of hydrogen, deuterium, and tritium, and also the plasma of noble gas such as helium, neon, and argon atoms are investigated. The possibility of fuzz formation is discussed on the simulation result of penetration depth of the incident atoms

Effects of hydrogen and helium irradiation on optical property of tungsten

International Nuclear Information System (INIS)

Kazutoshi Tokunaga; Tadashi Fujiwara; Naoaki Yoahida; Koichiro Ezato; Satoshi Suzuki; Masato Akiba

2006-01-01

Plasma-wall interactions cause surface modification, compositional and structural change on material surface due to sputtering, impurity deposition and radiation damage, etc. As a result, optical property (response of electron and lattice on material for electromagnetic wave) on surface of the plasma facing components would be changed. In particular, diagnostic components, such as metallic mirrors, mounted close to the plasma will be subjected by plasma particles such as hydrogen isotope and helium in the fusion devices. It is well recognized that decrease of optical reflectivity of the metallic mirrors due to the plasma-material interaction will be critical issues for the plasma diagnosis. In the present work, tungsten has been irradiated by hydrogen and helium beam. After that, optical reflectivity and surface modification have been measured to investigate fundamental process of optical property change due to hydrogen and helium beam irradiation. Samples used in the present experiment are powder metallurgy tungsten. Hydrogen and helium irradiations are performed in an ion beam facility at JAEA, the Particle Beam Engineering Facility (PBEF). The energy of hydrogen and helium is 19.0 and 18.7 keV, respectively. Beam duration is 1.3 - 3.5 s. The samples are irradiated up to a fluence of the orders between 10 22 and 10 24 He/m 2 by the repeated pulse irradiations of 14-450 cycles. The surface temperature is measured with an optical pyrometer. After the repeated irradiation experiments, surface modification and composition are examined with a scanning electron microscope (SEM) and a scanning probe microscope (SPM), etc. In addition, the optical reflectivity is measured in the wavelength range of 190 - 2400 nm using an ultraviolet-visible and near-infrared spectrophotometer. The reflectivity after the irradiation decreases depending on fluence and a peak temperature of the samples during the irradiation. In addition, their reflectivity spectra also change. This means

Orthogonal polarization in lasers physical phenomena and engineering applications

CERN Document Server

Zhang, Shulian

2013-01-01

This practical book summarizes the latest research results of orthogonally polarized lasers, birefringence laser cavities, and their applications. Coverage ranges from basic principles and technologies to the characteristics of different cavities and lasers to various measurement techniques. A number of figures, experimental designs, and measurement curves are included, helping readers gain a thorough understanding of the many applications in modern engineering and start their own projects. Many types of relevant lasers (Helium/Neon lasers, Nd:YAG lasers, laser diodes, etc.) are also discussed

Thermodynamic design of hydrogen liquefaction systems with helium or neon Brayton refrigerator

Science.gov (United States)

Chang, Ho-Myung; Ryu, Ki Nam; Baik, Jong Hoon

2018-04-01

A thermodynamic study is carried out for the design of hydrogen liquefaction systems with helium (He) or neon (Ne) Brayton refrigerator. This effort is motivated by our immediate goal to develop a small-capacity (100 L/h) liquefier for domestic use in Korea. Eight different cycles are proposed and their thermodynamic performance is investigated in comparison with the existing liquefaction systems. The proposed cycles include the standard and modified versions of He Brayton refrigerators whose lowest temperature is below 20 K. The Brayton refrigerator is in direct thermal contact with the hydrogen flow at atmospheric pressure from ambient-temperature gas to cryogenic liquid. The Linde-Hampson system pre-cooled by a Ne Brayton refrigerator is also considered. Full cycle analysis is performed with the real properties of fluids to estimate the figure of merit (FOM) under an optimized operation condition. It is concluded that He Brayton refrigerators are feasible for this small-scale liquefaction, because a reasonably high efficiency can be achieved with simple and safe (low-pressure) operation. The complete cycles with He Brayton refrigerator are presented for the development of a prototype, including the ortho-to-para conversion.

Influence of low-energy laser radiation on normal skin and certain tumor tissues

Energy Technology Data Exchange (ETDEWEB)

Pletnev, S.D.; Karpenko, O.M.

For some years, the authors' Institute has studied the influence of various types of low-energy laser radiation on normal tissue and the growth of tumors. Radiation at 3 and 30 J/cm/sup 2/ causes an increase in biological activity of various cell elements, manifested as an increase in mitotic activity of the cells in the basal layer of the epidermis, conglomeration of chromatin in the cell nuclei and an increase in degranulation of fat cells in the process of their migration to the reticular layer. Also noted was an increase in content of fibroblastic and lymphohistocytic elements in the dermis, as well as an increase in collagenization of connective tissue. It was found that irradiation of the skin by helium-neon, cadmium-helium and nitrogen lasers before and after grafting of the cells of various tumors modifies the course of the tumor process. This effect is apparently related to the fact that systematic irradiation results in changes creating a favorable background for survival and proliferation of tumor cells in the skin tissue medium. The changes facilitate an increase in survival and growth of both pigmented and nonpigmented tumors. Low power radiation stimulates the activity of the cells or cell structures; medium power stimulates their activity; high power suppresses activity.

Helium Neon laser therapy for post mastectomy lymphedema and ...

African Journals Online (AJOL)

Mohamed M. Khalaf

2012-12-08

Dec 8, 2012 ... mastectomy lymphedema and shoulder mobility. Mohamed M. Khalaf *. ,1 .... neurological and orthopedic problems, or diabetes. The patients were ... included 15 patients who received placebo laser therapy in addition to ...

Frequency stabilized HeNe gas laser with 3.5 mW from a single mode

NARCIS (Netherlands)

Ellis, J.D.; Voigt, D.; Spronck, J.W.; Verlaan, A.L.; Munnig Schmidt, R.H.

2012-01-01

This paper describes an optical frequency stabilization technique using a three-mode Helium Neon laser at 632.8 nm. Using this configuration, a maximum frequency stability relative to an iodine stabilized laser of 6×10 -12 (71 s integration time) was achieved. Two long term measurements of 62 h and

Effects of low energy helium plasma irradiation on potassium doped tungsten

Energy Technology Data Exchange (ETDEWEB)

Shu, Xiaoyan [Key Laboratory of Radiation Physics and Technology of Ministry of Education, Institute of Nuclear Science and Technology, Sichuan University, Chengdu (China); Key Subject Laboratory of National Defense for Radioactive Waste and Environmental Security, Southwest University of Science and Technology, Mianyang (China); Huang, Bo [Key Laboratory of Radiation Physics and Technology of Ministry of Education, Institute of Nuclear Science and Technology, Sichuan University, Chengdu (China); Liu, Dongping; Fan, Hongyu [School of Physics and Materials Engineering, Dalian Nationalities University, Dalian (China); Liu, Ning [Key Laboratory of Radiation Physics and Technology of Ministry of Education, Institute of Nuclear Science and Technology, Sichuan University, Chengdu (China); Tang, Jun, E-mail: tangjun@scu.edu.cn [Key Laboratory of Radiation Physics and Technology of Ministry of Education, Institute of Nuclear Science and Technology, Sichuan University, Chengdu (China)

2017-04-15

Effects of helium plasma irradiation on spark plasma sintering (SPS) W-K, pure W and traditionally sintered commercial W-K have been studied, concerning the density, grain size and potassium content as the influence factors. Pinholes are formed under 120 eV He ions at 600 °C and 1 × 10{sup 23} m{sup −2} fluence on the surface of all samples. It is found that SPS-sintered W-K shows the best irradiation resistance among the present samples, and SPS-sintered pure W exhibits higher irradiation tolerance than commercial W-K. Different He-plasma tolerance was observed among the SPS-sintered W-K samples due to varied potassium content and grain size. In addition, the microstructure evolution under helium irradiation, the growth-migration of helium bubbles and their interactions of potassium bubbles have also been discussed.

Laser spectroscopy of antiprotonic helium

CERN Document Server

Hori, M

2005-01-01

When antiprotons (i.e. the antimatter counterpart of protons) are stopped in helium gas, 97% of them annihilate within picoseconds by reacting with the helium nuclei; a 3% fraction, however, survive with an anomalously long lifetime of several microseconds. This longevity is due to the formation of antiprotonic helium, which is a three-body Rydberg atom composed of an antiproton, electron, and helium nucleus. The ASACUSA experimental collaboration has recently synthesized large numbers of these atoms using CERN's Antiproton Decelerator facility, and measured the atom's transition frequencies to 60 parts per billion by laser spectroscopy. By comparing the experimental results with recent three-body QED calculations and the known antiproton cyclotron frequency, we were able to show that the antiproton mass and charge are the same as the corresponding proton values to a precision of 10 parts per billion. Ongoing and future series of experiments will further improve the experimental precision by using chirp-compe...

Laser treatment of radish seed

International Nuclear Information System (INIS)

Kartalov, P.; Nidal, T.

1987-01-01

Trials were conducted in unheated plastic greenhouses in 1985-1986 to test the effect of laser treatment on radish seed. Seed of cv Saxia was irradiated with helio-neon laser of 632.8 Nm wave length at: 2-, 4- and 6-fold irradiation. Results showed that plants of all variants emerged almost simultaneously. The root mass was greatest for plants obtained from 4-fold irradiated seed. Treatment enhanced root production in 1985, and in 1986 4-fold irradiation boosted yield by 15%

In vivo and in vitro HeNe laser effects on phagocyte functions

Energy Technology Data Exchange (ETDEWEB)

Ricevuti, G.; Mazzone, A.; Monaia, C.; Fratino, P.; Degiulio, R.; Dell' Acqua, R.; Leonardi, G.; Jucci, A.; Sacchi, S. (Univ. of Pavia (Italy))

1989-10-01

The goal of this work was to evaluate the effect of helium-neon (HeNe) laser irradiation on immunocompetent cells. We used the in vivo skin window method and in vitro granulocyte function tests. The study of cellular migration showed a marked decrease in vitro and in vivo in a dose-independent manner. Superoxide release was not modified by laser irradiation. The granulocyte's aggregation, when using PHA and PMA, presented a reduction that was statistically very significant, not as a subordinate dose. An increase of the release of ATP was demonstrated only at 4 joules and precedes granulocyte aggregation. When using Ca2+ ionophore A23187 as stimulus, laser irradiation at 1, 2 or 4J did not show any modification of granulocyte aggregation. The monoclonal antibody 60.1, which identifies a membrane antigen fundamental for aggregation and chemotaxis, is expressed in normal amounts on granulocyte membranes both before and after irradiation with a HeNe laser. In fact, laser irradiation preferentially attacks the area of the cellular centrosome that determines a modification of cellular morphology. The electron microscope and immunofluorescence study with a monoclonal antibody have pointed out a disorganization of the microtubules. The alteration of some of the granulocyte functions is correlated to the damage in the centrioles. The granulocyte mitochondrial system and surface membrane remain intact, and this explains the normal production and release of free radicals. Further experiments are necessary to evaluate the clinical application of lasers in various diseases with immunophagocytic pathogenesis.

Control of helium effects in irradiated materials based on theory and experiment

International Nuclear Information System (INIS)

Mansur, L.K.; Lee, E.H.; Maziasz, P.J.; Rowcliffe, A.F.

1986-01-01

Helium produced in materials by (n,α) transmutation reactions during neutron irradiations or subjected in ion bombardment experiments causes substantial changes in the response to displacement damage. In particular, swelling, phase transformations and embrittlement are strongly affected. Present understanding of the mechanisms underlying these effects is reviewed. Key theoretical relationships describing helium effects on swelling and helium diffusion are described. Experimental data in the areas of helium effects on swelling and precipitation is reviewed with emphasis on critical experiments that have been designed and evaluated in conjunction with theory. Confirmed principles for alloy design to control irradiation performance are described

HEINBE; the calculation program for helium production in beryllium under neutron irradiation

International Nuclear Information System (INIS)

Shimakawa, Satoshi; Ishitsuka, Etsuo; Sato, Minoru

1992-11-01

HEINBE is a program on personal computer for calculating helium production in beryllium under neutron irradiation. The program can also calculate the tritium production in beryllium. Considering many nuclear reactions and their multi-step reactions, helium and tritium productions in beryllium materials irradiated at fusion reactor or fission reactor may be calculated with high accuracy. The calculation method, user's manual, calculated examples and comparison with experimental data were described. This report also describes a neutronics simulation method to generate additional data on swelling of beryllium, 3,000-15,000 appm helium range, for end-of-life of the proposed design for fusion blanket of the ITER. The calculation results indicate that helium production for beryllium sample doped lithium by 50 days irradiation in the fission reactor, such as the JMTR, could be achieved to 2,000-8,000 appm. (author)

The x-ray laser coherence experiments in neon-like yttrium

International Nuclear Information System (INIS)

Shimkaveg, G.M.; Carter, M.R.; Walling, R.S.; Ticehurst, J.M.; Koch, J.A.; Mrowka, S.; Trebes, J.E.; MacGowan, B.J.; Da Silva, L.B.; Matthews, D.L.; London, R.A.; Stewart, R.E.

1992-01-01

We present recent results from neon-like x-ray laser experiments conducted at the Nova laser's Two-Beam Facility. This begins a series of experiments aimed at the characterization and control of the degree of spatial coherece in our soft x-ray laser beams, important to planned applications areas susch as microscopy and holography. New instrumentation developed for this effort include a fully time-resolved coherence diagnostic (which records a multiple-slit diffraction pattern) and wide-angle extreme ultraviolet spectrographs and beam divergence cameras. We present new measurements of beam profiles and gain, as well as spatial coherence data such as time-resolved multi-slit diffraction patterns. This new time-resolved coherence data exhibit aperture functions which increase in size during the time of the lasing. Also, some preliminary data is given from the first ''double-foil'' experiments, involving two x-ray amplifiers spatially separated by 29 cm and shot sequentially, in an ''oscillator-amplifier'' configuration

Molecular dynamics and density functional simulations of tungsten nanostructure formation by helium plasma irradiation

International Nuclear Information System (INIS)

Ito, A.M.; Takayama, A.; Oda, Y.

2014-10-01

For the purposes of long-term use of tungsten diverter walls, it is necessary to suppress the surface deterioration due to the helium ash which induces the formations of helium bubbles and tungsten fuzzy nanostructures. In the present paper, the formation mechanisms of helium bubbles and tungsten fuzzy nanostructures were explained by the four-step process which is composed of the penetration process, the diffusion and agglomeration process, the helium bubble growth process and the tungsten fuzzy nanostructure formation process. The first to third step processes of the four-step process were investigated by using binary collision approximation, density functional theory and molecular dynamics, respectively. Furthermore, newly developed molecular dynamics and Monte-Carlo hybrid simulation has successfully reproduced the early formation process of tungsten fuzzy nanostructure. From these simulations, we here suggest the following key mechanisms of the formations of helium bubbles and tungsten fuzzy nanostructures: (1) By comparison between helium, neon, argon and hydrogen, the noble gas atoms can agglomerate limitlessly not only at a vacancy but also at an interstitial site. In particular, at the low incident energy, only helium atoms bring about the nucleation for helium bubble. (2) In the helium bubble growth process, the strain of the tungsten material around a helium atom is released as a dislocation loop, which is regarded as the loop punching phenomenon. (3) In the tungsten nanostructure formation process, the bursting of a helium bubble forms cavity and convexity in the surface. The helium bubbles tend to be grown and to burst at the cavity region, and then the difference of height between the cavity and convexity on the surface are enhanced. Consequently, the tungsten fuzzy nanostructure is formed. (author)

Effects of sequential helium and hydrogen ion irradiation on the nucleation and evolution of bubbles in tungsten

Energy Technology Data Exchange (ETDEWEB)

Shen, Zhenyu; Zheng, Zhongcheng [Hubei Nuclear Solid Physics Key Laboratory, Key Laboratory of Artificial Micro- and Nano-Structures of Ministry of Education and School of Physics and Technology, Wuhan University, Wuhan, 430072 (China); Luo, Fengfeng [Hubei Nuclear Solid Physics Key Laboratory, Key Laboratory of Artificial Micro- and Nano-Structures of Ministry of Education and School of Physics and Technology, Wuhan University, Wuhan, 430072 (China); Institute of Applied Physics, Jiangxi Academy of Science, Nanchang, 330029 (China); Hu, Wenhui [Hubei Nuclear Solid Physics Key Laboratory, Key Laboratory of Artificial Micro- and Nano-Structures of Ministry of Education and School of Physics and Technology, Wuhan University, Wuhan, 430072 (China); Institute of Plasma Physics, Chinese Academy of Sciences, Hefei, 230031 (China); Zhang, Weiping [Hubei Nuclear Solid Physics Key Laboratory, Key Laboratory of Artificial Micro- and Nano-Structures of Ministry of Education and School of Physics and Technology, Wuhan University, Wuhan, 430072 (China); Guo, Liping, E-mail: guolp@whu.edu.cn [Hubei Nuclear Solid Physics Key Laboratory, Key Laboratory of Artificial Micro- and Nano-Structures of Ministry of Education and School of Physics and Technology, Wuhan University, Wuhan, 430072 (China); Ren, Yaoyao [Center for Electron Microscopy, Wuhan University, Wuhan, 430072 (China)

2017-02-15

Highlights: • The effect of H{sup +} irradiation on formation and evolution of helium bubbles is explored. • The growth of hydrogen bubbles under He{sup +} irradiation is observed. • Mechanism of synergistic effect between He and H is discussed. - Abstract: Irradiations of He{sup +} and H{sup +} have been performed to investigate the effect of H{sup +} irradiation on existing helium bubbles and the effect of pre-irradiation of H{sup +} on the formation of helium bubbles in tungsten. The specimens were irradiated at 800 °C with either 10kev-H{sup +}, 20kev-He{sup +}, or sequentially irradiated with both H{sup +} and He{sup +}. After H{sup +} irradiation, the growth of existing helium bubbles was observed. It was also found that pre- or post- irradiation of H{sup +} enhanced the nucleation of helium bubbles. The growth of hydrogen bubbles was also observed after post irradiation of He{sup +}. The possible mechanism is discussed.

Interference of laser-induced resonances in the continuous structures of a helium atom

International Nuclear Information System (INIS)

Magunov, A I; Strakhova, S I

2003-01-01

Coherent effects in the interference of overlapping laser-induced resonances in helium atoms are considered. The simultaneous action of single-mode radiation of the 294-nm second harmonic of a cw dye laser and a 1064-nm Nd:YAG laser on helium atoms provides the overlap of two resonances induced by transitions from the 1s2s 1 S and 1s4s 1 S helium levels. The shape of the overlapping laser-induced resonances in the rotating-wave approximation is described by analytic expressions, which depend on the laser radiation intensities and the ratio of laser frequencies. (nonlinear optical phenomena)

Effect of combined misonidazole and accelerated neon ions on a human melanoma transplanted into nude mice

International Nuclear Information System (INIS)

Guichard, M.; Tenforde, T.; Curtis, S.; Malaise, E.P.

1982-01-01

The response to accelerated neon ions of human Nall melanomas growing in nude mice was measured by an in vitro colony-forming assay following in situ tumor irradiation in the midposition of a 10-cm extended-peak ionization region. Values of the relative biological effectiveness (RBE) for peak neon ions compared with 60 Coγ radiation were 3.2 and 3.4, respectively, at the 1% and 10% survival levels. Following irradiation with peak neon ions, the repair of potentially lethal damage (PLD) was comparable to that observed after γ irradiation. When misonidazole (1 mg/g intraperitoneal dose) was administered in combination with extended-peak neon ions, the drug enhancement ratio (ER) at the 1% survival level was 1.5 if the tumors were removed and plated in vitro immediately following irradiation, and 1.9 if tumor excision and plating were delayed for greater than or equal to 6 hours. Administration of misonidazole completely inhibited PLD repair following either γ irradiation or extended peak neon-ion irradiation

Analysis of neon soft x-ray spectra from short-pulse laser-produced plasmas

International Nuclear Information System (INIS)

Abare, A.C.; Keane, C.J.; Crane, J.K.; DaSilva, L.B.; Lee, R.W.; Perry, M.D.; Falcone, R.W.

1993-04-01

We report preliminary results from the analysis of streaked soft x-ray neon spectra a gas jet target. In obtained from the interaction of a picosecond Nd:glass laser with these experiments streaked spectra show prompt harmonic emission followed by longer time duration soft x-ray line emission. The majority of the line emission observed was found to originate from Li- and Be-like Ne and the major transitions in the observed spectra have been identified. Li-like emission lines were observed to decay faster in time than Be-like transitions, suggesting that recombination is taking place. Line ratios of n=4-2 and n=3-2 transitions supported the view that these lines were optically thin and thick, respectively. The time history of Li-like Ne 2p-4d and 2p-3d lines is in good agreement with a simple adiabatic expansion model coupled to a time dependent collisional-radiative code. Further x-ray spectroscopic analysis is underway which is aimed at diagnosing plasma conditions and assessing the potential of this recombining neon plasma as a quasi-steady-state recombination x-ray laser medium

Experimental method for investigating helium effects in irradiated vanadium

International Nuclear Information System (INIS)

Smith, D.L.; Matsui, H.; Greenwood, L.; Loomis, B.

1987-10-01

Analyses have been performed which indicate that an effective method for experimentally investigating helium effects in neutron irradiated vanadium base alloys can be developed. The experimental procedure involves only modest modifications to existing procedures currently used for irradiation testing of vanadium-base alloys in the FFTF reactor. Helium is generated in the vanadium alloy by decay of tritium which is either preinjected or generated within the test capsule. Calculations indicate that nearly constant He/dpa ratios of desired magnitude can be attained by proper selection of experimental parameters. The proposed method could have a major impact on the development of vanadium base alloys for fusion reactor applications. 8 refs., 4 figs

Radiolysis study of actinide complexing agent by irradiation with helium ion beam

International Nuclear Information System (INIS)

Sugo, Yumi; Taguchi, Mitsumasa; Sasaki, Yuji; Hirota, Koichi; Kimura, Takaumi

2009-01-01

α-Radiolysis of N,N,N',N'-tetraoctyldiglycolamide (TODGA) in n-dodecane was investigated by the irradiation with helium ion beam provided by a tandem accelerator. The radiation chemical yield for the degradation of TODGA by helium ion beam irradiation was less than that by γ-rays irradiation. It is considered that the radical cations of n-dodecane, which contribute to the charge transfer reaction with the TODGA molecules, decrease by recombination in track by high LET radiations such as α-particles.

Demonstrating Fluorescence with Neon Paper and Plastic

Science.gov (United States)

Birriel, Jennifer J.; Roe, Clarissa

2015-01-01

Several papers in this journal have dealt with the fluorescence in orange neon plastic, olive oil, and soda. In each case, the fluorescent emission was excited by either green or violet-blue laser light. In this paper, we examine the fluorescent emission spectra of so-called neon colored papers and plastic clipboards available in department and…

Effects of helium content of microstructural development in Type 316 stainless steel under neutron irradiation

International Nuclear Information System (INIS)

Maziasz, P.J.

1985-11-01

This work investigated the sensitivity of microstructural evolution, particularly precipitate development, to increased helium content during thermal aging and during neutron irradiation. Helium (110 at. ppM) was cold preinjected into solution annealed (SA) DO-heat type 316 stainess steel (316) via cyclotron irradiation. These specimens were then exposed side by side with uninjected samples. Continuous helium generation was increased considerably relative to EBR-II irradiation by irradiation in HFIR. Data were obtained from quantitative analytical electron microscopy (AEM) in thin foils and on extraction replicas. 480 refs., 86 figs., 19 tabs

Effects of helium content of microstructural development in Type 316 stainless steel under neutron irradiation

Energy Technology Data Exchange (ETDEWEB)

Maziasz, P.J.

1985-11-01

This work investigated the sensitivity of microstructural evolution, particularly precipitate development, to increased helium content during thermal aging and during neutron irradiation. Helium (110 at. ppM) was cold preinjected into solution annealed (SA) DO-heat type 316 stainess steel (316) via cyclotron irradiation. These specimens were then exposed side by side with uninjected samples. Continuous helium generation was increased considerably relative to EBR-II irradiation by irradiation in HFIR. Data were obtained from quantitative analytical electron microscopy (AEM) in thin foils and on extraction replicas. 480 refs., 86 figs., 19 tabs.

Standard Guide for Simulation of Helium Effects in Irradiated Metals

CERN Document Server

American Society for Testing and Materials. Philadelphia

1996-01-01

1.1 This guide provides advice for conducting experiments to investigate the effects of helium on the properties of metals where the technique for introducing the helium differs in some way from the actual mechanism of introduction of helium in service. Simulation techniques considered for introducing helium shall include charged particle implantation, exposure to α-emitting radioisotopes, and tritium decay techniques. Procedures for the analysis of helium content and helium distribution within the specimen are also recommended. 1.2 Two other methods for introducing helium into irradiated materials are not covered in this guide. They are the enhancement of helium production in nickel-bearing alloys by spectral tailoring in mixed-spectrum fission reactors, and isotopic tailoring in both fast and mixed-spectrum fission reactors. These techniques are described in Refs (1-5). Dual ion beam techniques (6) for simultaneously implanting helium and generating displacement damage are also not included here. This lat...

The effect of helium generation and irradiation temperature on tritium release from neutron irradiated beryllium

International Nuclear Information System (INIS)

Kupriyanov, I.B.; Gorokhov, V.A.; Vlasov, V.V.; Kovalev, A.M.; Chakin, V.P.

2004-01-01

The effect of neutron irradiation condition on tritium release from beryllium is described in this paper. Beryllium samples were irradiated in the SM reactor with neutron fluence (E > 0.1 MeV) of (0.37-2.0) x 10 22 cm -2 at 70-100degC and 650-700degC. Mass-spectrometer technique was used in out of tritium release experiments during stepped-temperature anneal within a temperature range from 250 to 1300degC. The total amount of helium accumulated in irradiated beryllium samples varied from 521 appm to 3061 appm. The first signs of tritium release were detected at temperature of 406-553degC. It was shown that irradiation temperature and helium generation level significantly affect the tritium release. A fraction of 44 - 74 % of tritium content in samples irradiated at low temperature (70 - 100degC) is release from beryllium at an annealing temperature below 800degC, whereas for samples after high temperature irradiation (650 - 700 degC) tritium release did not exceed 14 %. Majority of tritium (∼68%) is released within a temperature range from 800 to 920 degC. The increase of helium generation from 521 appm to 3061 appm results in lowering the temperature of maximal tritium release rate and the upper temperature of tritium release from beryllium by 100-130degC and 200-240degC, correspondingly. On the basis of data obtained, the diffusion coefficients of tritium in beryllium were calculated. (author)

Tritium and helium release from beryllium pebbles neutron-irradiated up to 230appm tritium and 3000appm helium

Directory of Open Access Journals (Sweden)

Vladimir Chakin

2016-12-01

Full Text Available Study of tritium and helium release from beryllium pebbles with diameters of 0.5 and 1mm after high-dose neutron irradiation at temperatures of 686–968K was performed. The release rate always has a single peak, and the peak temperatures at heating rates of 0.017K/s and 0.117K/s lie in the range of 1100–1350K for both tritium and helium release. The total tritium release from 1mm pebbles decreases considerably by increasing the irradiation temperature. The total tritium release from 0.5mm pebbles is less than that from 1mm pebbles and remains constant regardless of the irradiation temperature. At high irradiation temperatures, open channels are formed which contribute to the enhanced tritium release.

Tritium and helium retention and release from irradiated beryllium

Energy Technology Data Exchange (ETDEWEB)

Anderl, R.A.; Longhurst, G.R.; Oates, M.A.; Pawelko, R.J. [Idaho National Engineering and Environmental Lab., Idaho Falls, ID (United States)

1998-01-01

This paper reports the results of an experimental effort to anneal irradiated beryllium specimens and characterize them for steam-chemical reactivity experiments. Fully-dense, consolidated powder metallurgy Be cylinders, irradiated in the EBR-II to a fast neutron (>0.1 MeV) fluence of {approx}6 x 10{sup 22} n/cm{sup 2}, were annealed at temperatures from 450degC to 1200degC. The releases of tritium and helium were measured during the heat-up phase and during the high-temperature anneals. These experiments revealed that, at 600degC and below, there was insignificant gas release. Tritium release at 700degC exhibited a delayed increase in the release rate, while the specimen was at 700degC. For anneal temperatures of 800degC and higher, tritium and helium release was concurrent and the release behavior was characterized by gas-burst peaks. Essentially all of the tritium and helium was released at temperatures of 1000degC and higher, whereas about 1/10 of the tritium was released during the anneals at 700degC and 800degC. Measurements were made to determine the bulk density, porosity and specific surface area for each specimen before and after annealing. These measurements indicated that annealing caused the irradiated Be to swell, by as much as 14% at 700degC and 56% at 1200degC. Kr gas adsorption measurements for samples annealed at 1000degC and 1200degC determined specific surface areas between 0.04 m{sup 2}/g and 0.1 m{sup 2}/g for these annealed specimens. The tritium and helium gas release measurements and the specific surface area measurements indicated that annealing of irradiated Be caused a porosity network to evolve and become surface-connected to relieve internal gas pressure. (author)

Detection and control of as-produced pyrocarbon permeability in biso-coated high-temperature gas-cooled reactor fuel particles

International Nuclear Information System (INIS)

Stinton, D.P.; Thiele, B.A.; Lackey, W.J.; Morgan, C.S.

1980-05-01

About 60 Biso-coated particle batches with coatings deposited in either 0.13- or 0.24-m dia coaters were studied in this work. These batches were carefully characterized for permeability by neon-helium intrusion, long-term chlorination followed by radiography, and fission gas release. These methods of permeability measurement were compared and correlated with deposition conditions as well as pyrocarbon properties. The results from several irradiation tests were also used to evaluate the validity of the permeability measurements. The neon-helium and long-term chlorination techniques correlated very clearly. Coatings with neon-to-helium ratios below 0.3 were gastight by the chlorination procedure, whereas those with ratios above 0.4 were permeable. The fission gas release technique was unable to distinguish between slightly permeable coatings and gastight ones. Therefore, neon-helium and long-term chlorination procedures are preferred over the fission gas release technique. Results from several irradiation tests verified that coatings with neon-to-helium ratios below 0.3 were gastight, whereas those with ratios above about 0.4 were permeable. 10 figures, 2 tables

Calculation of displacement and helium production at the LAMPF irradiation facility

International Nuclear Information System (INIS)

Davidson, D.R.; Greenwood, L.R.; Sommer, W.F.; Wechsler, M.S.

1984-01-01

Differential and total displacement and helium production rates are calculated for copper irradiated by spallation neutrons and 760 MeV protons at LAMPF. The calculations are performed using the SPECTER and VNMTC computer codes, the latter being specially designed for spallation radiation damage calculations. For comparison, similar SPECTER calculations are also described for irradiation of copper in EBR-II and RTNS-II. The results indicate substantial contributions to the displacement and helium production rates due to neutrons in the high-energy tail (above 40 MeV) of the LAMPF spallation neutron spectrum. Still higher production rates are calculated for irradiations in the direct proton beam. These results will provide useful background information for research to be conducted at a new irradiation facility at LAMPF

Properties of vanadium-base alloys irradiated in the Dynamic Helium Charging Experiment*1

Science.gov (United States)

Chung, H. M.; Loomis, B. A.; Smith, D. L.

1996-10-01

One property of vanadium-base alloys that is not well understood in terms of their potential use a fusion reactor structural materials, is the effect of simultaneous generation of helium and neutron damage. In the present Dynamic Helium Charging Experiment (DHCE), helium was produced uniformly in the specimen at linear rates of ≈ 0.4 to 4.2 appm helium/dpa by the decay of tritium during irradiation to 18-31 dpa at 425-600°C in Li-filled capsules in a sodium-cooled fast reactor. This paper presents results of postirradiation examination and tests of microstructure and mechanical properties of V5Ti, V3Ti1Si, V8Cr6Ti, and V4Cr4Ti (the latter alloy has been identified as the most promising candidate vanadium alloy). Effects of helium on tensile strength and ductility were insignificant after irradiation and testing at > 420°C. However, postirradiation ductilities at irradiation. Ductile—brittle transition behavior of the DHCE specimens was also determined from bend tests and fracture appearance of transmission electron microscopy (TEM) disks and broken tensile specimens. No brittle behavior was observed at temperatures > - 150°C in DHCE specimens. Predominantly brittle-cleavage fracture morphologies were observed only at - 196°C in some specimens that were irradiated to 31 dpa at 425°C during the DHCE. For the helium generation rates in this experiment (≈ 0.4-4.2 appm He/dpa), grain-boundary coalescence of helium microcavities was negligible and intergranular fracture was not observed.

Soft-tissue injuries from sports activities and traffic accidents--treatment with low-level laser therapy: a multicenter double-blind placebo-controlled clinical study on 132 patients

Science.gov (United States)

Simunovic, Zlatko; Trobonjaca, Tatjana

2000-06-01

The aim of current multicenter clinical study was to assess the efficacy of low energy-level laser therapy (LLLT) in the treatment of soft tissue injuries compared to the placebo and classical phyiotherapeutic procedures. This clinical study was conducted in two centers located in Locarno, Switzerland and Opatija, Croatia. Two types of irradiation techniques were used: (1) direct, skin contact technique for treatment of trigger points where IR diode laser 830 nm continuous wave was applied; and (2) scanning technique for irradiation of larger surface area with use of Helium Neon laser 632.8 nm combined with IR diode laser 904 nm pulsed wave. Results were evaluated according to clinical parameters like: hematoma, swelling, heat, pan and loss of function. The findings were statistically analyzed via chi- square test. Results have demonstrated that the recovery process was accelerated in 85 percent of patients treated with LLLT compared to the control group of patients. The results and advantages obtained proved once again the efficacy of LLLT as a new and successful way to treat soft tissue injuries.

Studies on the influence of laser beams on wound granulation

International Nuclear Information System (INIS)

Brunner, R.

1982-01-01

The influence of laser light of law energy on wound healing was tested on 204 rats in a blind study. The growth of granulation tissue in a polyvinylchloride cylinder implanted on the backs of the animals served as parameter for wound healing. Irradiation was carried out with a helium-neon laser (wavelength 632.8 nm) at daily doses of 0.5 J/cm 2 , 1.5 J/cm 2 , 4 J/cm 2 , 10 J/cm 2 and 20 J/cm 2 , and with incoherent non-linear polarized red light (wavelength 630 nm) with a daily dose of 4 J/cm 2 . This was repeated 8 times. Laser irradiation caused a statistically significant increase in wet and dry granulation tissue weight of 25% in the dose range 1.5 J/cm 2 to 20 J/cm 2 . At 0.5 J/cm 2 the effect was less, but the least effect was achieved by non-linear polarized incoherent red light. Bacteriological evaluation of wound germ counts revealed a marginally lower presence of high germ cell densities. In irradiated animals, histological and enzyme cytochemical findings revealed, in addition to a significant findings revealed, in addition to a significant increase in mast cells, a smaller increase in fibroblast count and a slight decrease in granulocytic and histiocytic elements. The biochemical evaluation of granulation tissue revealed no differences in collagen content between irradiated and unirradiated animals. (orig.) [de

Damage behavior in helium-irradiated reduced-activation martensitic steels at elevated temperatures

Energy Technology Data Exchange (ETDEWEB)

Luo, Fengfeng [Key Laboratory of Artificial Micro- and Nano-Structures of Ministry of Education, Hubei Nuclear Solid Physics Key Laboratory and School of Physics and Technology, Wuhan University, Wuhan 430072 (China); Guo, Liping, E-mail: guolp@whu.edu.cn [Key Laboratory of Artificial Micro- and Nano-Structures of Ministry of Education, Hubei Nuclear Solid Physics Key Laboratory and School of Physics and Technology, Wuhan University, Wuhan 430072 (China); Chen, Jihong; Li, Tiecheng; Zheng, Zhongcheng [Key Laboratory of Artificial Micro- and Nano-Structures of Ministry of Education, Hubei Nuclear Solid Physics Key Laboratory and School of Physics and Technology, Wuhan University, Wuhan 430072 (China); Yao, Z. [Department of Mechanical and Materials Engineering, Queen’s University, Kingston K7L 3N6, ON (Canada); Suo, Jinping [State Key Laboratory of Mould Technology, Institute of Materials Science and Engineering, Huazhong University of Science and Technology, Wuhan 430074 (China)

2014-12-15

Dislocation loops induced by helium irradiation at elevated temperatures in reduced-activation martensitic steels were investigated using transmission electron microscopy. Steels were irradiated with 100 keV helium ions to 0.8 dpa between 300 K and 723 K. At irradiation temperatures T{sub irr} ⩽ 573 K, small defects with both Burger vectors b = 1/2〈1 1 1〉 and b = 〈1 0 0〉 were observed, while at T{sub irr} ⩾ 623 K, the microstructure was dominated by large convoluted interstitial dislocation loops with b = 〈1 0 0〉. Only small cavities were found in the steels irradiated at 723 K.

Binary-collision-approximation-based simulation of noble gas irradiation to tungsten materials

International Nuclear Information System (INIS)

Saito, Seiki; Takayama, Arimichi; Ito, Atsushi M.; Nakamura, Hiroaki

2013-01-01

To reveal the possibility of fuzz formation of tungsten material under noble gas irradiation, helium, neon, and argon atom injections into tungsten materials are performed by binary-collision-approximation-based simulation. The penetration depth is strongly depends on the structure of the target material. Therefore, the penetration depth for amorphous and bcc crystalline structure is carefully investigated in this paper

Tensile properties of helium-injected V-15Cr-5Ti after irradiation in EBR-II

International Nuclear Information System (INIS)

Grossbeck, M.L.; Horak, J.A.

1985-01-01

Miniature specimens of V-15Cr-5Ti were prepared in the annealed condition and with 10, 20, and 30% cold work. The annealed specimens were cyclotron injected with helium and irradiated in sodium in EBR-II. The cold-worked specimens were irradiated in EBR-II but not helium injected. The specimens were irradiated at 400, 525, 625, and 700 0 C and received a fluence of 4.1 to 5.5 x 10 26 neutrons/m 2 (E > 0.1 meV). Tensile testing revealed very significant embrittlement as a result of the neutron irradiation but a much smaller change, mostly at 400 0 C, resulting from helium injection. 5 references, 9 figures, 2 tables

Low energy helium ion irradiation induced nanostructure formation on tungsten surface

International Nuclear Information System (INIS)

Al-Ajlony, A.; Tripathi, J.K.; Hassanein, A.

2017-01-01

We report on the low energy helium ion irradiation induced surface morphology changes on tungsten (W) surfaces under extreme conditions. Surface morphology changes on W surfaces were monitored as a function of helium ion energy (140–300 eV), fluence (2.3 × 10 24 –1.6 × 10 25 ions m −2 ), and flux (2.0 × 10 20 –5.5 × 10 20 ion m −2 s −1 ). All the experiments were performed at 900° C. Our study shows significant effect of all the three ion irradiation parameters (ion flux, fluence, and energy) on the surface morphology. However, the effect of ion flux is more pronounced. Variation of helium ion fluence allows to capture the very early stages of fuzz growth. The observed fuzz growth and morphology changes were understood in the realm of various possible phenomena. The study has relevance and important impact in the current and future nuclear fusion applications. - Highlights: •Reporting formation of W nanostructure (fuzz) due to low energy He ion beam irradiation. •Observing the very early stages for the W-Fuzz formation. •Tracking the surface morphological evolution during the He irradiation. •Discussing in depth our observation and drawing a possible scenario that explain this phenomenon. •Studying various ions irradiation parameters such as flux, fluence, and ions energy.

The absolute photoionization cross sections of helium, neon, argon and krypton in the extreme vacuum ultraviolet region of the spectrum

International Nuclear Information System (INIS)

West, J.B.; Marr, G.V.

1976-01-01

An experiment has been set up at the Daresbury Synchrotron Radiation Facility to make absolute absorption cross section measurements over a wide range of photon energies. New data are reported for helium, neon, argon and krypton over the range 340 to 40 A which are believed to be reliable to +- 5%. A critical evaluation of published cross section data has been carried out to produce best value data from the ionization thresholds throughout the vacuum ultraviolet and x-ray region. Agreement with theoretical calculations on helium is demonstrated to be within +- 2 to 3% from threshold down to the double ionization threshold at 79 eV. Comparison with recent calculations of photoionization cross sections has shown that the effect of electron correlations is significant for the heavier inert gases. Contrary to previous claims, the position of the M shell maximum in krypton is located at 184 +- 10 eV in good agreement with r.p.a.e. calculations. Oscillator strength sum rules have been examined and their moments calculated. Discrepancies developing towards the heavier inert gases suggests a decrease in polarizabilities and other atomic factors from those predicted by Hartree-Fock calculations. (author)

Influence of the helium-pressure on diode-pumped alkali-vapor laser

Science.gov (United States)

Gao, Fei; Chen, Fei; Xie, Ji-jiang; Zhang, Lai-ming; Li, Dian-jun; Yang, Gui-long; Guo, Jing

2013-05-01

Diode-pumped alkali-vapor laser (DPAL) is a kind of laser attracted much attention for its merits, such as high quantum efficiency, excellent beam quality, favorable thermal management, and potential scalability to high power and so on. Based on the rate-equation theory of end-pumped DPAL, the performances of DPAL using Cs-vapor collisionally broadened by helium are simulated and studied. With the increase of helium pressure, the numerical results show that: 1) the absorption line-width increases and the stimulated absorption cross-section decreases contrarily; 2) the threshold pumping power decreases to minimum and then rolls over to increase linearly; 3) the absorption efficiency rises to maximum initially due to enough large stimulated absorption cross-section in the far wings of collisionally broadened D2 transition (absorption transition), and then begins to reduce; 4) an optimal value of helium pressure exists to obtain the highest output power, leading to an optimal optical-optical efficiency. Furthermore, to generate the self-oscillation of laser, a critical value of helium pressure occurs when small-signal gain equals to the threshold gain.

Radiation blistering of niobium in sequence irradiated by helium ions with different energy

International Nuclear Information System (INIS)

Das, S.K.; Kaminskij, M.S.; Guseva, M.I.; Gusev, V.M.; Krasulin, Yu.L.; Martynenko, Yu.V.; Rozina, I.A.

1977-01-01

The results of the investigation of the blistering of the surface of polycrystalline niobium foils subjected to successive irradiation by helium ions of energies of 3 to 50 keV are reported. The critical doses of irradiation, the types of blisters and the rate of erosion were determined. A comparative analysis of the formation of blisters on cold-rolled and annealed niobium has been made. On cold-rolled niobium the blistering is mainly due to ions with energies of 3 to 80 keV, on annealed niobium of 100 to 500 keV. The erosion of cold-rolled niobium takes place through blisters formed by the action of helium ions with energies of the order of 45 keV, and that of annealed niobium, through helium ions with energies of 100 to 500 keV. The observed differences in the formation of blisters on niobium irradiated with helium ions of a wide range of energies are explained by the change in the diffusion kinetics of implanted ions having a uniform distribution across the thickness of the target

Low energy helium ion irradiation induced nanostructure formation on tungsten surface

Energy Technology Data Exchange (ETDEWEB)

Al-Ajlony, A., E-mail: montaserajlony@yahoo.com; Tripathi, J.K.; Hassanein, A.

2017-05-15

We report on the low energy helium ion irradiation induced surface morphology changes on tungsten (W) surfaces under extreme conditions. Surface morphology changes on W surfaces were monitored as a function of helium ion energy (140–300 eV), fluence (2.3 × 10{sup 24}–1.6 × 10{sup 25} ions m{sup −2}), and flux (2.0 × 10{sup 20}–5.5 × 10{sup 20} ion m{sup −2} s{sup −1}). All the experiments were performed at 900° C. Our study shows significant effect of all the three ion irradiation parameters (ion flux, fluence, and energy) on the surface morphology. However, the effect of ion flux is more pronounced. Variation of helium ion fluence allows to capture the very early stages of fuzz growth. The observed fuzz growth and morphology changes were understood in the realm of various possible phenomena. The study has relevance and important impact in the current and future nuclear fusion applications. - Highlights: •Reporting formation of W nanostructure (fuzz) due to low energy He ion beam irradiation. •Observing the very early stages for the W-Fuzz formation. •Tracking the surface morphological evolution during the He irradiation. •Discussing in depth our observation and drawing a possible scenario that explain this phenomenon. •Studying various ions irradiation parameters such as flux, fluence, and ions energy.

Láser helio-neón combinado con clorhexidina al 0,2 %.: Efectos clínicos y microbiológicos en el tratamiento de la gingivitis crónica Helium-neon laser combined with 0.2% chlorhexidine: Clinical and microbiological effects in the treatment of chronic gingivitis.

Directory of Open Access Journals (Sweden)

Tatiana Peña Ruiz

2007-09-01

Full Text Available La gingivitis crónica constituye una de las formas más frecuentes de enfermedad periodontal, caracterizada por la inflamación crónica de la encías, tumefacción, enrojecimiento y sangramiento. Su principal factor de riesgo lo constituye la microbiota del surco gingival, que resulta necesario, pero no suficiente para desencadenarla. Se realizó un ensayo clínico-terapéutico fase II, controlado, aleatorizado y a simple ciegas, para evaluar los efectos clínicos y microbiológicos del tratamiento combinado de la radiación láser helio-neón (He-Ne con la clorhexidina al 0,2 %. Todos los pacientes recibieron tratamiento inicial; al mes de finalizado este, se distribuyeron aleatoriamente en 2 grupos: un grupo estudio que recibió la combinación láser-neón y clorhexidina al 0,2 % y otro grupo control que solo recibió clorhexidina al 0,2 %. Se realizó una evaluación a los 15, 30 y 45 días, con criterios de eficacia clínicos y microbiológicos. Los resultados clínicos fueron satisfactorios en el grupo estudio con predominio de los morfotipos I, caracterizados por cocos gramnegativos y positivos, compatibles con un periodonto sano. Los eventos adversos detectados con esta terapéutica fueron mínimos, todos relacionados con la somnolencia.Chronic gingivitis is one of the most common periodontal diseases that is characterized by chronic inflammation, tumefaction, redness and bleeding. The main risk factor is gingival sulcus microbiota that is essential but not enough to unleash it. A phase II controlled randomized blind clinical/therapeutical assay was conducted to evaluate the clinical and microbiological effects of the combined treatment based on helium-neon laser (He-Ne with 0.2% chlorhexidine. All the patients were initially treated; after a month, they were randomly distributed into two groups, that is, the study group received a helium-neon laser plus 0.2% chlorhexidine combination and the control group was treated with 0

Microstructural evolution in dual-ion irradiated 316SS under various helium injection schedules

International Nuclear Information System (INIS)

Kohyama, A.; Igata, N.; Ayrault, G.; Tokyo Univ.

1984-01-01

Dual-ion irradiated 316 SS samples with various helium injection schedules were studied. The intent of using different schedules was to either approximate the MFR condition, mimic the mixed spectrum reactor condition or mimic the fast reactor condition. The objective of this investigation is to study the influence of these different helium injection schedules on the microstructural development under irradiation. The materials for this study was 316 SS (MFE heat) with three thermomechanical pre-irradiation treatments: solution annealed, solution annealed and aged and 20% cold worked. The cavity nucleation and growth stages were investigated using high resolution TEM. (orig.)

Digital Communication System Based on Polarization Self-Modulation in Lasers

Science.gov (United States)

Tabarin, V. A.; Ikonnikov, V. P.; Shatalov, A. N.

2014-09-01

Polarization self-modulation in lasers can be used to create instruments for generating optical pulses at very high repetition rates without using high-speed electronics. Self-oscillation is observed when part of the output of a laser is returned to the laser after a 90° polarization change. A practical scheme based on polarization self-modulation in a 3.39-μm helium-neon laser is proposed for pulsed code data transmission with an yttrium-iron garnet magnetooptical Q-switch. Highly efficient transmission of digital signals is implemented with a repetition rate of 75 MHz, equivalent to half the free spectral range of the laser.

Calculation of displacement and helium production at the LAMPF irradiation facility

International Nuclear Information System (INIS)

Wechsler, M.S.; Davidson, D.R.; Sommer, W.F.; Greenwood, L.R.

1985-01-01

Differential and total displacement and helium-production rates are calculated for copper irradiated by spallation neutrons and 760-MeV protons at LAMPF. The calculations are performed using the SPECTOR and VNMTC computer codes, the latter being specially designed for spallation radiation-damage calculations. For comparison, similar SPECTER calculations are also described for irradiation of copper in the experimental breeder reactor (EBR-II) at the Argonne National Laboratory-West in Idaho, and in the rotating target neutron source (RTNS-II) at Lawrence Livermore Laboratory. The neutron energy spectra for LAMPF, EBR-II, and RTNS-II and the displacement and helium-production cross sections are shown

Irradiation performance of helium-bonded uranium--plutonium carbide fuel elements

International Nuclear Information System (INIS)

Latimer, T.W.; Petty, R.L.; Kerrisk, J.F.; DeMuth, N.S.; Levine, P.J.; Boltax, A.

1979-01-01

The current irradiation program of helium-bonded uranium--plutonium carbide elements is achieving its original goals. By August 1978, 15 of the original 171 helium-bonded elements had reached their goal burnups including one that had reached the highest burnup of any uranium--plutonium carbide element in the U.S.--12.4 at.%. A total of 66 elements had attained burnups over 8 at.%. Only one cladding breach had been identified at that time. In addition, the systematic and coordinated approach to the current steady-state irradiation tests is yielding much needed information on the behavior of helium-bonded carbide fuel elements that was not available from the screening tests (1965 to 1974). The use of hyperstoichiometric (U,Pu)C containing approx. 10 vol% (U,Pu) 2 C 3 appears to combine lower swelling with only a slightly greater tendency to carburize the cladding than single-phase (U,Pu)C. The selected designs are providing data on the relationship between the experimental parameters of fuel density, fuel-cladding gap size, and cladding type and various fuel-cladding mechanical interaction mechanisms

Laser Induced Fluorescence of Helium Ions in a Helicon Plasma

Science.gov (United States)

Compton, C. S.; Biloui, C.; Hardin, R. A.; Keesee, A. M.; Scime, E. E.; Boivin, R.

2003-10-01

The lack of a suitable Laser Induced Fluorescence (LIF) scheme for helium ions at visible wavelengths has prevented LIF from being employed in helium plasmas for measurements of ion temperature and bulk ion flow speeds. In this work, we will discuss our attempts to perform LIF of helium ions in a helicon source plasma using an infrared, tunable diode laser operating at 1012.36 nm. The infrared transition corresponds to excitation from the n = 4 level (4f ^2F) to the n = 5 (5g ^2G) level of singly ionized helium and therefore requires substantial electron temperatures (> 10 eV) to maintain an adequate ion population in the n = 4 state. Calculations using a steady state coronal model predict that the n = 4 state population will be 25% larger than the n = 5 population for our experimental conditions. The fluorescence decay from the n = 5 (5f ^2F) level of singly ionized helium level to the n = 3 (3d ^2D) level at 320.31 nm is monitored as the diode laser is swept through 10 GHz around the 1012.36 nm line. Note that the fluorescence emission requires a collisionally coupled transition between two different n = 5 quantum states. We will also present measurements of the emission intensities of both the 1012.36 nm and the 320.31 nm lines as a function of source neutral pressure, rf power, and plasma density. This work supported by the U.S. DoE EPSCoR Lab Partnership Program.

Supersonic jets of hydrogen and helium for laser wakefield acceleration

CERN Document Server

Svensson, K.; Wojda, F.; Senje, L.; Burza, M.; Aurand, B.; Genoud, G.; Persson, A.; Wahlström, C.-G.; Lundh, O.

2016-01-01

The properties of laser wakefield accelerated electrons in supersonic gas flows of hydrogen and helium are investigated. At identical backing pressure, we find that electron beams emerging from helium show large variations in their spectral and spatial distributions, whereas electron beams accelerated in hydrogen plasmas show a higher degree of reproducibility. In an experimental investigation of the relation between neutral gas density and backing pressure, it is found that the resulting number density for helium is ∼30% higher than for hydrogen at the same backing pressure. The observed differences in electron beam properties between the two gases can thus be explained by differences in plasma electron density. This interpretation is verified by repeating the laser wakefield acceleration experiment using similar plasma electron densities for the two gases, which then yielded electron beams with similar properties.

Supersonic jets of hydrogen and helium for laser wakefield acceleration

Directory of Open Access Journals (Sweden)

K. Svensson

2016-05-01

Full Text Available The properties of laser wakefield accelerated electrons in supersonic gas flows of hydrogen and helium are investigated. At identical backing pressure, we find that electron beams emerging from helium show large variations in their spectral and spatial distributions, whereas electron beams accelerated in hydrogen plasmas show a higher degree of reproducibility. In an experimental investigation of the relation between neutral gas density and backing pressure, it is found that the resulting number density for helium is ∼30% higher than for hydrogen at the same backing pressure. The observed differences in electron beam properties between the two gases can thus be explained by differences in plasma electron density. This interpretation is verified by repeating the laser wakefield acceleration experiment using similar plasma electron densities for the two gases, which then yielded electron beams with similar properties.

Synergistic effect of helium and hydrogen for bubble swelling in reduced-activation ferritic/martensitic steel under sequential helium and hydrogen irradiation at different temperatures

Energy Technology Data Exchange (ETDEWEB)

Hu, Wenhui [Key Laboratory of Artificial Micro- and Nano-structures of Ministry of Education, Hubei Nuclear Solid Physics Key Laboratory and School of Physics and Technology, Wuhan University, Wuhan 430072 (China); Guo, Liping, E-mail: guolp@whu.edu.cn [Key Laboratory of Artificial Micro- and Nano-structures of Ministry of Education, Hubei Nuclear Solid Physics Key Laboratory and School of Physics and Technology, Wuhan University, Wuhan 430072 (China); Chen, Jihong; Luo, Fengfeng; Li, Tiecheng [Key Laboratory of Artificial Micro- and Nano-structures of Ministry of Education, Hubei Nuclear Solid Physics Key Laboratory and School of Physics and Technology, Wuhan University, Wuhan 430072 (China); Ren, Yaoyao [Center for Electron Microscopy, Wuhan University, Wuhan 430072 (China); Suo, Jinping; Yang, Feng [State Key Laboratory of Mould Technology, Institute of Materials Science and Engineering, Huazhong University of Science and Technology, Wuhan 430074 (China)

2014-04-15

Highlights: • Helium/hydrogen synergistic effect can increase irradiation swelling of RAFM steel. • Hydrogen can be trapped to the outer surface of helium bubbles. • Too large a helium bubble can become movable. • Point defects would become mobile and annihilate at dislocations at high temperature. • The peak swelling temperature for RAFM steel is 450 °C. - Abstract: In order to investigate the synergistic effect of helium and hydrogen on swelling in reduced-activation ferritic/martensitic (RAFM) steel, specimens were separately irradiated by single He{sup +} beam and sequential He{sup +} and H{sup +} beams at different temperatures from 250 to 650 °C. Transmission electron microscope observation showed that implantation of hydrogen into the specimens pre-irradiated by helium can result in obvious enhancement of bubble size and swelling rate which can be regarded as a consequence of hydrogen being trapped by helium bubbles. But when temperature increased, Ostwald ripening mechanism would become dominant, besides, too large a bubble could become mobile and swallow many tiny bubbles on their way moving, reducing bubble number density. And these effects were most remarkable at 450 °C which was the peak bubble swelling temperature for RAMF steel. When temperature was high enough, say above 450, point defects would become mobile and annihilate at dislocations or surface. As a consequence, helium could no longer effectively diffuse and clustering in materials and bubble formation was suppressed. When temperature was above 500, helium bubbles would become unstable and decompose or migrate out of surface. Finally no bubble was observed at 650 °C.

Synergistic effect of helium and hydrogen for bubble swelling in reduced-activation ferritic/martensitic steel under sequential helium and hydrogen irradiation at different temperatures

International Nuclear Information System (INIS)

Hu, Wenhui; Guo, Liping; Chen, Jihong; Luo, Fengfeng; Li, Tiecheng; Ren, Yaoyao; Suo, Jinping; Yang, Feng

2014-01-01

Highlights: • Helium/hydrogen synergistic effect can increase irradiation swelling of RAFM steel. • Hydrogen can be trapped to the outer surface of helium bubbles. • Too large a helium bubble can become movable. • Point defects would become mobile and annihilate at dislocations at high temperature. • The peak swelling temperature for RAFM steel is 450 °C. - Abstract: In order to investigate the synergistic effect of helium and hydrogen on swelling in reduced-activation ferritic/martensitic (RAFM) steel, specimens were separately irradiated by single He + beam and sequential He + and H + beams at different temperatures from 250 to 650 °C. Transmission electron microscope observation showed that implantation of hydrogen into the specimens pre-irradiated by helium can result in obvious enhancement of bubble size and swelling rate which can be regarded as a consequence of hydrogen being trapped by helium bubbles. But when temperature increased, Ostwald ripening mechanism would become dominant, besides, too large a bubble could become mobile and swallow many tiny bubbles on their way moving, reducing bubble number density. And these effects were most remarkable at 450 °C which was the peak bubble swelling temperature for RAMF steel. When temperature was high enough, say above 450, point defects would become mobile and annihilate at dislocations or surface. As a consequence, helium could no longer effectively diffuse and clustering in materials and bubble formation was suppressed. When temperature was above 500, helium bubbles would become unstable and decompose or migrate out of surface. Finally no bubble was observed at 650 °C

Development of a sodium-pump/neon-lasant photopumped soft X-ray laser

International Nuclear Information System (INIS)

Stephanakis, S.J.; Apruzese, J.P.; Burkhalter, P.G.

1988-01-01

Resonant photopumping of heliumlike neon by heliumlike sodium is investigated to extend this potentially efficient technique for inversion and lasing to shorter wavelengths. Properties of the sodium-pump plasma and the neon-lasant plasma required to optimize fluorescence and lasing are determined. The implosion of a sodium-bearing plasma with a megampere pulsed-power driver (Gamble II) is used to produce a linear Z-pinch with up to 25 GW of sodium-pump-line radiation. A separate neon plasma, driven by part of the return current form the imploding sodium plasma, is created parallel to the sodium line source at a distance of 5 cm. Implosion requirements for the neon plasma and its dynamics in the Gamble II return-current geometry are described. Evidence for population inversion is indicated by fluorescence enhancement of the 11-A resonance line from the n = 4 level of neon when pumped by sodium. The neon spectra are in qualitative agreement with calculations based on the sodium-pump power. Improvements in the experiment required to achieve lasing are discussed

Neon dewar for the X-ray spectrometer onboard Suzaku

Energy Technology Data Exchange (ETDEWEB)

Fujimoto, R. [Institute of Space and Astronautical Science (ISAS), JAXA, 3-1-1 Yoshinodai, Sagamihara 229-8510 (Japan)]. E-mail: fujimoto@isas.jaxa.jp; Mitsuda, K. [Institute of Space and Astronautical Science (ISAS), JAXA, 3-1-1 Yoshinodai, Sagamihara 229-8510 (Japan); Hirabayashi, M. [Sumitomo Heavy Industries, Ltd. (SHI), 5-2 Sobiraki-cho, Niihama 792-8588 (Japan); Narasaki, K. [Sumitomo Heavy Industries, Ltd. (SHI), 5-2 Sobiraki-cho, Niihama 792-8588 (Japan); Breon, S. [NASA Goddard Space Flight Center (GSFC), Greenbelt, MD 20771 (United States); Boyle, R. [NASA Goddard Space Flight Center (GSFC), Greenbelt, MD 20771 (United States); Di Pirro, M. [NASA Goddard Space Flight Center (GSFC), Greenbelt, MD 20771 (United States); Volz, S.M. [NASA Headquarters, Washington, DC 20546-0001 (United States); Kelley, R.L. [NASA Goddard Space Flight Center (GSFC), Greenbelt, MD 20771 (United States)

2006-04-15

The X-ray spectrometer (XRS) onboard Suzaku is the first X-ray microcalorimeter array in orbit. The sensor array is operated at 60mK, which is attained by an adiabatic demagnetization refrigerator and superfluid liquid helium. The neon dewar is a vacuum-insulated container for the XRS. The requirements for the XRS dewar are to maintain the detector and the cryogenic system under the mechanical environment at launch ({approx}15G), and to attain a lifetime of 3 years in a near-earth orbit. It is characterized with adoptions of solid neon as the second cryogen and a mechanical cooler, design optimization of the support straps for the neon tank to reduce the heat load as much as possible, and shock absorbers to mitigate the mechanical environment at launch. Microphonics from the mechanical cooler was one of the concerns for the detector performance, but the ground test results proved that they do not interfere with the detector. After about 1 month in orbit, its thermal performance showed that the dewar potentially achieves its design goals.

Space and time resolved spectroscopy of laser-produced plasmas: A study of density-sensitive x-ray transitions in helium-like and neon-like ions

Energy Technology Data Exchange (ETDEWEB)

Young, Bruce Kai Fong

1988-09-01

The determination of level populations and detailed population mechanisms in dense plasmas has become an increasingly important problem in atomic physics. In this work, the density variation of line intensities and level populations in aluminum K-shell and molybdenum and silver L-shell emission spectra have been measured from high-powered, laser-produced plasmas. For each case, the density dependence of the observed line emission is due to the effect of high frequency electron-ion collisions on metastable levels. The density dependent line intensities vary greatly in laser-produced plasmas and can be used to extract detailed information concerning the population kinetics and level populations of the ions. The laser-plasmas had to be fully characterized in order to clearly compare the observed density dependence with atomic theory predictions. This has been achieved through the combined use of new diagnostic instruments and microdot targets which provided simultaneously space, time, and spectrally resolved data. The plasma temperatures were determined from the slope of the hydrogen-like recombination continuum. The time resolved electron density profiles were measured using multiple frame holographic interferometry. Thus, the density dependence of K-shell spectral lines could be clearly examined, independent of assumptions concerning the dynamics of the plasma. In aluminum, the electron density dependence of various helium-like line intensity ratios were measured. Standard collisional radiative equilibrium models fail to account for the observed density dependence measured for the ''He/sub ..cap alpha..//IC'' ratio. Instead, a quasi-steady state atomic model based on a purely recombining plasma is shown to accurately predict the measured density dependence. This same recombining plasma calculation successfully models the density dependence of the high-n ''He/sub ..gamma..//He/sub ..beta../'' and ''He/sub delta

Space and time resolved spectroscopy of laser-produced plasmas: A study of density-sensitive x-ray transitions in helium-like and neon-like ions

International Nuclear Information System (INIS)

Young, Bruce Kai Fong.

1988-09-01

The determination of level populations and detailed population mechanisms in dense plasmas has become an increasingly important problem in atomic physics. In this work, the density variation of line intensities and level populations in aluminum K-shell and molybdenum and silver L-shell emission spectra have been measured from high-powered, laser-produced plasmas. For each case, the density dependence of the observed line emission is due to the effect of high frequency electron-ion collisions on metastable levels. The density dependent line intensities vary greatly in laser-produced plasmas and can be used to extract detailed information concerning the population kinetics and level populations of the ions. The laser-plasmas had to be fully characterized in order to clearly compare the observed density dependence with atomic theory predictions. This has been achieved through the combined use of new diagnostic instruments and microdot targets which provided simultaneously space, time, and spectrally resolved data. The plasma temperatures were determined from the slope of the hydrogen-like recombination continuum. The time resolved electron density profiles were measured using multiple frame holographic interferometry. Thus, the density dependence of K-shell spectral lines could be clearly examined, independent of assumptions concerning the dynamics of the plasma. In aluminum, the electron density dependence of various helium-like line intensity ratios were measured. Standard collisional radiative equilibrium models fail to account for the observed density dependence measured for the ''He/sub α//IC'' ratio. Instead, a quasi-steady state atomic model based on a purely recombining plasma is shown to accurately predict the measured density dependence. This same recombining plasma calculation successfully models the density dependence of the high-n ''He/sub γ//He/sub β/'' and ''He/sub δ//He/sub β/'' helium-like resonance line intensity ratios

Skin blood flow from gas transport: helium xenon and laser Doppler compared

Energy Technology Data Exchange (ETDEWEB)

Neufeld, G.R.; Galante, S.R.; Whang, J.M.; DeVries, D.; Baumgardner, J.E.; Graves, D.J.; Quinn, J.A.

1988-03-01

A study was designed to compare three independent measures of cutaneous blood flow in normal healthy volunteers: xenon-133 washout, helium flux, and laser velocimetry. All measurements were confined to the volar aspect of the forearm. In a large group of subjects we found that helium flux through intact skin changes nonlinearly with the controlled local skin temperature whereas helium flux through stripped skin, which is directly proportional to skin blood flow, changes linearly with cutaneous temperature over the range 33 degrees to 42 degrees. In a second group of six volunteers we compared helium flux through stripped skin to xenon-133 washout (intact skin) at a skin temperature of 33 degrees, and we found an essentially linear relationship between helium flux and xenon measured blood flow. In a third group of subjects we compared helium flux blood flow (stripped skin) to laser doppler velocimetric (LDV) measurements (intact skin) at adjacent skin sites and found a nonlinear increase in the LDV skin blood flow compared to that determined by helium over the same temperature range. A possible explanation for the nonlinear increases of helium flux through intact skin and of LDV output with increasing local skin temperature is that they reflect more than a change in blood flow. They may also reflect physical changes in the stratum corneum, which alters its diffusional resistance to gas flux and its optical characteristics.

Skin blood flow from gas transport: helium xenon and laser Doppler compared

International Nuclear Information System (INIS)

Neufeld, G.R.; Galante, S.R.; Whang, J.M.; DeVries, D.; Baumgardner, J.E.; Graves, D.J.; Quinn, J.A.

1988-01-01

A study was designed to compare three independent measures of cutaneous blood flow in normal healthy volunteers: xenon-133 washout, helium flux, and laser velocimetry. All measurements were confined to the volar aspect of the forearm. In a large group of subjects we found that helium flux through intact skin changes nonlinearly with the controlled local skin temperature whereas helium flux through stripped skin, which is directly proportional to skin blood flow, changes linearly with cutaneous temperature over the range 33 degrees to 42 degrees. In a second group of six volunteers we compared helium flux through stripped skin to xenon-133 washout (intact skin) at a skin temperature of 33 degrees, and we found an essentially linear relationship between helium flux and xenon measured blood flow. In a third group of subjects we compared helium flux blood flow (stripped skin) to laser doppler velocimetric (LDV) measurements (intact skin) at adjacent skin sites and found a nonlinear increase in the LDV skin blood flow compared to that determined by helium over the same temperature range. A possible explanation for the nonlinear increases of helium flux through intact skin and of LDV output with increasing local skin temperature is that they reflect more than a change in blood flow. They may also reflect physical changes in the stratum corneum, which alters its diffusional resistance to gas flux and its optical characteristics

High-power frequency-stabilized laser for laser cooling of metastable helium at 389 nm

NARCIS (Netherlands)

Koelemeij, J.C.J.; Hogervorst, W.; Vassen, W.

2005-01-01

A high-power, frequency-stabilized laser for cooling of metastable helium atoms using the 2 S13 →3 P23 transition at 389 nm has been developed. The 389 nm light is generated by frequency doubling of a titanium:sapphire laser in an external enhancement cavity containing a lithium-triborate nonlinear

Spectral broadening of 25 fs laser pulses via self-phase modulation in a neon filled hollow core fibre

Energy Technology Data Exchange (ETDEWEB)

Weichert, Stefan

2017-05-15

The goal of this work was the realisation of a setup for spectral broadening and subsequent compression of 25 fs laser pulses provided by a commercial Ti:Sapphire based CPA laser system by means of the hollow core fibre chirped mirror compressor technique. For the spectral broadening a vessel containing the hollow waveguide filled with a noble gas serving as the nonlinear medium was set up and an alignment procedure was developed. Neon was chosen as the nonlinear medium for the self-phase modulation of the pulses. With this setup spectral broadening, sufficient for supporting sub 5 fs pulses, was observed. The spectra at different input energies and neon gas pressures were measured and the stability of these and their respective Fourier transform-limited pulses determined in order to find an operating point. For the compression of the self-phase modulated pulses a chirped mirror compressor was designed and set up, but not tested yet. The layout of a single-shot intensity autocorrelator capable of estimating the pulse duration of sub 10 fs pulses was given.

Spectral broadening of 25 fs laser pulses via self-phase modulation in a neon filled hollow core fibre

International Nuclear Information System (INIS)

Weichert, Stefan

2017-05-01

The goal of this work was the realisation of a setup for spectral broadening and subsequent compression of 25 fs laser pulses provided by a commercial Ti:Sapphire based CPA laser system by means of the hollow core fibre chirped mirror compressor technique. For the spectral broadening a vessel containing the hollow waveguide filled with a noble gas serving as the nonlinear medium was set up and an alignment procedure was developed. Neon was chosen as the nonlinear medium for the self-phase modulation of the pulses. With this setup spectral broadening, sufficient for supporting sub 5 fs pulses, was observed. The spectra at different input energies and neon gas pressures were measured and the stability of these and their respective Fourier transform-limited pulses determined in order to find an operating point. For the compression of the self-phase modulated pulses a chirped mirror compressor was designed and set up, but not tested yet. The layout of a single-shot intensity autocorrelator capable of estimating the pulse duration of sub 10 fs pulses was given.

Fatigue behavior of Type 316 stainless steel following neutron irradiation inducing helium

International Nuclear Information System (INIS)

Grossbeck, M.L.; Liu, K.C.

1980-01-01

Since a tokamak reactor operates in a cyclic mode, thermal stresses will result in fatigue in structural components, especially in the first wall and blanket. There has been limited work on fatigue in irradiated alloys but none on irradiated materials containing significant amounts of irradiation-induced helium. To provide scoping data and to study the effects of irradiation on fatigue behavior, 20%-cold-worked type 316 stainless steel from the MFE reference heat was studied

An interbubble fracture mechanism of blister formation on helium-irradiated metals

International Nuclear Information System (INIS)

Evans, J.H.

1977-01-01

This paper describes a new model of surface blister formation in which a blister is nucleated by the interbubble fracture of highly overpressurized helium bubbles. As in other gas-driven models, the internal release of helium then provides the driving force for blister lid deformation. The high pressures required for the suggested mode of fracture are a result of the difficulty, experienced by the bubbles in acquiring vacancies. By considering the bubble growth mechanisms, the critical conditions for interbubble fracture are shown to depend on the helium dose and energy, the bubble size, and their depth in the irradiated material. These parameters and other aspects of blister formation are discussed on the basis of the proposed model. One important result concerns the position of the fracture plane; because of the usual displacement of damage and helium peaks relative to depth, this plane can lie well beyond the helium peak. Thus, the disagreement inherent in previous gas models between helium range and measured blister lid thickness values can be resolved without recourse to lateral stress arguments. (Auth.)

Cluster dynamics modeling of the effect of high dose irradiation and helium on the microstructure of austenitic stainless steels

Energy Technology Data Exchange (ETDEWEB)

Brimbal, Daniel, E-mail: Daniel.brimbal@areva.com [AREVA NP, Tour AREVA, 1 Place Jean Millier, 92084 Paris La Défense (France); Fournier, Lionel [AREVA NP, Tour AREVA, 1 Place Jean Millier, 92084 Paris La Défense (France); Barbu, Alain [Alain Barbu Consultant, 6 Avenue Pasteur Martin Luther King, 78230 Le Pecq (France)

2016-01-15

A mean field cluster dynamics model has been developed in order to study the effect of high dose irradiation and helium on the microstructural evolution of metals. In this model, self-interstitial clusters, stacking-fault tetrahedra and helium-vacancy clusters are taken into account, in a configuration well adapted to austenitic stainless steels. For small helium-vacancy cluster sizes, the densities of each small cluster are calculated. However, for large sizes, only the mean number of helium atoms per cluster size is calculated. This aspect allows us to calculate the evolution of the microstructural features up to high irradiation doses in a few minutes. It is shown that the presence of stacking-fault tetrahedra notably reduces cavity sizes below 400 °C, but they have little influence on the microstructure above this temperature. The binding energies of vacancies to cavities are calculated using a new method essentially based on ab initio data. It is shown that helium has little effect on the cavity microstructure at 300 °C. However, at higher temperatures, even small helium production rates such as those typical of sodium-fast-reactors induce a notable increase in cavity density compared to an irradiation without helium. - Highlights: • Irradiation of steels with helium is studied through a new cluster dynamics model. • There is only a small effect of helium on cavity distributions in PWR conditions. • An increase in helium production causes an increase in cavity density over 500 °C. • The role of helium is to stabilize cavities via reduced emission of vacancies.

Four-body conversion of atomic helium ions

International Nuclear Information System (INIS)

de Vries, C.P.; Oskam, H.J.

1980-01-01

The conversion of atomic helium ions into molecular ions was studied in pure helium and in helium-neon mixtures containing between 0.1 at. % and 50 at. % neon. The experiments showed that the termolecular conversion reaction, He + +2He → He 2 + +He, is augmented by the four-body conversion reaction He + +3He → products, where the products could include either He 2 + or He 3 + ions. Conversion rate coefficients of (5.7 +- 0.8) x 10 -32 cm 6 sec -1 and (2.6 +- 0.4) x 10 -49 cm 9 sec -1 were found for the termolecular and four-body conversion reactions, respectively. In addition, rate coefficients for the following Ne + conversion reactions were measured: Ne + +He+He → (HeNe) + +He, (2.3 +- 0.1) x 10 -32 cm 6 sec -1 ; Ne + +He+Ne → (HeNe) + +Ne or Ne 2 + +He, (8.0 +- 0.8) x 10 -32 cm 6 sec -1 ; and Ne + +Ne+Ne → Ne 2 + +Ne, (5.1 +- 0.3) x 10 -32 cm 6 sec -1 . All rate coefficients are at a gas temperature of 295 K

Treatment of cancer with heavy charged particles

International Nuclear Information System (INIS)

Castro, J.R.

1981-01-01

The clinical radiotherapy trial has accured 243 patients irradiated with particles and 13 patients irradiated as controls in randomized studies. Of the 243 particle patients, 194 have been treated with helium ions, either solely or in combination with photon irradiation, and 49 have received all or part of their irradiation with one of the heavier particles, either carbon, neon, or argon ions. The project thus can be divided into two general phases: (1) evaluation of improved dose distribution without significant biologic advantage by use of helium ion irradiation; and (2) evaluation of improved dose distribution and enhanced biologic effect by irradiation with heavy charged particles such as carbon, neon, and argon ions

Rare resource supply crisis and solution technology for semiconductor manufacturing

Science.gov (United States)

Fukuda, Hitomi; Hu, Sophia; Yoo, Youngsun; Takahisa, Kenji; Enami, Tatsuo

2016-03-01

There are growing concerns over future environmental impact and earth resource shortage throughout the world and in many industries. Our semiconductor industry is not excluded. "Green" has become an important topic as production volume become larger and more powerful. Especially, the rare gases are widely used in semiconductor manufacturing because of its inertness and extreme chemical stability. One major component of an Excimer laser system is Neon. It is used as a buffer gas for Argon (Ar) and Krypton (Kr) gases used in deep ultraviolet (DUV) lithography laser systems. Since Neon gas accounting for more than 96% of the laser gas mixture, a fairly large amount of neon gas is consumed to run these DUV lasers. However, due to country's instability both in politics and economics in Ukraine, the main producer of neon gas today, supply reduction has become an issue and is causing increasing concern. This concern is not only based on price increases, but has escalated to the point of supply shortages in 2015. This poses a critical situation for the semiconductor industry, which represents the leading consumer of neon gas in the world. Helium is another noble gas used for Excimer laser operation. It is used as a purge gas for optical component modules to prevent from being damaged by active gases and impurities. Helium has been used in various industries, including for medical equipment, linear motor cars, and semiconductors, and is indispensable for modern life. But consumption of helium in manufacturing has been increased dramatically, and its unstable supply and price rise has been a serious issue today. In this article, recent global supply issue of rare resources, especially Neon gas and Helium gas, and its solution technology to support semiconductor industry will be discussed.

Charge collection in Si detectors irradiated in situ at superfluid helium temperature

Science.gov (United States)

Verbitskaya, Elena; Eremin, Vladimir; Zabrodskii, Andrei; Dehning, Bernd; Kurfürst, Christoph; Sapinski, Mariusz; Bartosik, Marcin R.; Egorov, Nicolai; Härkönen, Jaakko

2015-10-01

Silicon and diamond detectors operated in a superfluid helium bath are currently being considered for the upgrade of the LHC beam loss monitoring system. The detectors would be installed in immediate proximity of the superconducting coils of the triplet magnets. We present here the results of the in situ irradiation test for silicon detectors using 23 GeV protons while keeping the detectors at a temperature of 1.9 K. Red laser (630 nm) Transient Current Technique and DC current measurements were used to study the pulse response and collected charge for silicon detectors irradiated to a maximum radiation fluence of 1×1016 p/cm2. The dependence between collected charge and irradiation fluence was parameterized using the Hecht equation and assumption of a uniform electric field distribution. The collected charge was found to degrade with particle fluence for both bias polarities. We observed that the main factor responsible for this degradation was related to trapping of holes on the donor-type radiation-induced defects. In contrast to expectations, along with formation of donors, acceptor-type defects (electron traps) are introduced into the silicon bulk. This suggests that the current models describing charge collection in irradiated silicon detectors require an extension for taking into account trapping at low temperatures with a contribution of shallow levels. New in situ irradiation tests are needed and planned now to extend statistics of the results and gain a deeper insight into the physics of low temperature detector operation in harsh radiation environment.

Laser signals' nonlinear change in fatty acids

CERN Document Server

Ghelmez-Dumitru, M; Piscureanu, M; Sterian, A

2003-01-01

Previous works showed that thin layers of fatty acids and fatty acid-cholesterol mixtures behaved as optical liquid crystals, even at low incident laser power. The paper presents an experimental and computer study of laser signals, emergent from such samples, in presence of fluctuations. The optical emergent laser beams' features at different incident parameters were experimentally determined for different type (c.w. and pulsed) lasers, as for example helium-neon and Nd sup 3 sup + glass lasers. The results were correlated with the amount of cholesterol in mixtures and with their response in external electric field. These measurements are in all cases affected by fluctuations. We developed some computer-based procedures, by using the TableCurve3D from Jandel Scientific software and equations Runge-Kutta in MATLAB for taking into account these fluctuations.

Note: Simple 100 Hz N2 laser with longitudinal discharge tube and high-voltage power supply using neon sign transformer.

Science.gov (United States)

Uno, K; Jitsuno, T

2017-12-01

We developed a longitudinally excited N 2 laser with a simple driver circuit and a simple power supply. The N 2 laser consisted of a 20 cm-long glass tube with an inner diameter of 2.5 mm, a normal stable resonator formed by flat mirrors, a variable transformer, a neon sign transformer, a spark gap, and a 200 pF capacitance. The N 2 laser produced a laser pulse with an energy of 379 nJ and a pulse width of 7.5 ns at a repetition rate of 100 Hz. The laser beam was circular and had a Gaussian profile with a correlation factor of 0.992 93.

Influence of irradiation conditions on plasma evolution in laser-surface interaction

Science.gov (United States)

Hermann, J.; Boulmer-Leborgne, C.; Dubreuil, B.; Mihailescu, I. N.

1993-09-01

The plasma plume induced by pulsed CO2 laser irradiation of a Ti target at power densities up to 4×108 W cm-2 was studied by emission spectroscopy. Time- and space-resolved measurements were performed by varying laser intensity, laser temporal pulse shape, ambient gas pressure, and the nature of the ambient gas. Experimental results are discussed by comparison with usual models. We show that shock wave and plasma propagation depend critically on the ratio Ivap/Ii, Ivap being the intensity threshold for surface vaporization and Ii the plasma ignition threshold of the ambient gas. Spectroscopic diagnostics of the helium breakdown plasma show maximum values of electron temperature and electron density in the order of kTe˜10 eV and ne=1018 cm-3, respectively. The plasma cannot be described by local thermodynamic equilibrium modeling. Nevertheless, excited metal atoms appear to be in equilibrium with electrons, hence, they can be used like a probe to measure the electron temperature. In order to get information on the role of the plasma in the laser-surface interaction, Ti surfaces were investigated by microscopy after irradiation. Thus an enhanced momentum transfer from the plasma to the target due to the recoil pressure of the breakdown plasma could be evidenced.

Helium in chirped laser fields as a time-asymmetric atomic switch

Czech Academy of Sciences Publication Activity Database

Kaprálová-Žďánská, Petra Ruth; Moiseyev, N.

2014-01-01

Roč. 141, č. 1 (2014), 014307 ISSN 0021-9606 R&D Projects: GA ČR GAP205/11/0571 Institutional support: RVO:61388955 Keywords : Atom lasers * Laser pulses * Helium Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 2.952, year: 2014

Evaluation of defect formation in helium irradiated Y2O3 doped W-Ti alloys by positron annihilation and nanoindentation

Science.gov (United States)

Richter, Asta; Anwand, Wolfgang; Chen, Chun-Liang; Böttger, Roman

2017-10-01

Helium implanted tungsten-titanium ODS alloys are investigated using positron annihilation spectroscopy and nanoindentation. Titanium reduces the brittleness of the tungsten alloy, which is manufactured by mechanical alloying. The addition of Y2O3 nanoparticles increases the mechanical properties at elevated temperature and enhances irradiation resistance. Helium ion implantation was applied to simulate irradiation effects on these materials. The irradiation was performed using a 500 kV He ion implanter at fluences around 5 × 1015 cm-2 for a series of samples both at room temperature and at 600 °C. The microstructure and mechanical properties of the pristine and irradiated W-Ti-ODS alloy are compared with respect to the titanium and Y2O3 content. Radiation damage is studied by positron annihilation spectroscopy analyzing the lifetime and the Doppler broadening. Three types of helium-vacancy defects were detected after helium irradiation in the W-Ti-ODS alloy: small defects with high helium-to-vacancy ratio (low S parameter) for room temperature irradiation, larger open volume defects with low helium-to-vacancy ratio (high S parameter) at the surface and He-vacancy complexes pinned at nanoparticles deeper in the material for implantation at 600 °C. Defect induced hardness was studied by nanoindentation. A drastic hardness increase is observed after He ion irradiation both for room temperature and elevated irradiation temperature of 600 °C. The Ti alloyed tungsten-ODS is more affected by the hardness increase after irradiation compared to the pure W-ODS alloy.

Effect of helium on swelling and microstructural evolution in ion-irradiated V-15Cr-5Ti alloy

International Nuclear Information System (INIS)

Loomis, B.A.; Kestel, B.J.; Gerber, S.B.; Ayrault, G.

1986-03-01

An investigation was made on the effects of implanted helium on the swelling and microstructural evolution that results from energetic single- and dual-ion irradiation of the V-15Cr-5Ti alloy. Single-ion irradiations were utilized for a simulated production of the irradiation damage that might be expected from neutron irradiation of the alloy in a reactor with a fast neutron energy spectrum (E > 0.1 MeV). Dual-ion irradiations were utilized for a simulated production of the simultaneous creation of helium atoms and irradiation damage in the alloy in the MFR environment. Experimental results are also presented on the radiation-induced segregation of the constituent atoms in the single- and dual-ion irradiated alloy

Determination of occluded helium and oxygen in irradiated borosilicate glass samples

International Nuclear Information System (INIS)

Ramanjaneyulu, P.S.; Kulkarni, A.S.; Shrivastava, K.C.; Yadav, C.S.; Saxena, M.K.; Tomar, B.S.; Ramakumar, K.L.; Shah, J.G.

2015-01-01

Occluded gases in irradiated borosilicate glass were determined at 573, 873 and 1273 K for understanding the radiation damage in glass matrix. Hot vacuum extraction coupled with a quadrupole mass spectrometer technique was employed for the measurements. Relative sensitivity factors of various gases in QMS system were also determined and used for gas composition calculations. At 573 K only helium was found to get released whereas at 873 and 1273 K both helium and oxygen were released with major fraction of oxygen. (author)

Novel nuclear laser spectroscopy method using superfluid helium for measurement of spins and moments of exotic nuclei

International Nuclear Information System (INIS)

Furukawa, Takeshi; Wakui, Takashi; Yang, Xiaofei; Fujita, Tomomi; Imamura, Kei; Yamaguchi, Yasuhiro; Tetsuka, Hiroki; Tsutsui, Yoshiki; Mitsuya, Yosuke; Ichikawa, Yuichi; Ishibashi, Yoko; Yoshida, Naoki; Shirai, Hazuki; Ebara, Yuta; Hayasaka, Miki; Arai, Shino; Muramoto, Sosuke

2013-01-01

Highlights: • Development of a novel nuclear laser spectroscopy method using superfluid helium. • Observation of the Zeeman resonance with the 85 Rb beam introduced into helium. • Demonstration of deducing the nuclear spins from the observed resonance spectrum. -- Abstract: We have been developing a novel nuclear laser spectroscopy method “OROCHI” for determining spins and moments of exotic radioisotopes. In this method, we use superfluid helium as a stopping material of energetic radioisotope beams and then stopped radioisotope atoms are subjected to in situ laser spectroscopy in superfluid helium. To confirm the feasibility of this method for rare radioisotopes, we carried out a test experiment using a 85 Rb beam. In this experiment, we have successfully measured the Zeeman resonance signals from the 85 Rb atoms stopped in superfluid helium by laser-RF double resonance spectroscopy. This method is efficient for the measurement of spins and moments of more exotic nuclei

Optical breakdown of helium in Bessel laser radiation beams

International Nuclear Information System (INIS)

Andreev, N E; Pleshanov, I V; Margolin, L Ya; Pyatnitskii, Lev N

1998-01-01

Numerical simulation is used to investigate the dynamics of formation of a helium plasma in Bessel beams, shaped by an axicon and a phase converter from a laser radiation pulse with Gaussian temporal and radial intensity profiles. The beam intensities at the breakdown threshold are determined as a function of the pulse duration for various radial field distributions in a beam characterised by Bessel functions of order m (m = 0 - 5). It is shown that in the investigated range of parameters the threshold intensity is independent of m. The temporal and spatial evolution of the resultant plasma, and the dependence of the plasma characteristics on the pulse parameters are considered. Conditions are found for the formation of tubular plasma channels in beams of orders m≥1. The adopted model of the optical breakdown of helium is shown to be satisfactory because of a good agreement between the results of calculations of the moment of breakdown in a zeroth-order Bessel beam and experimental results. (interaction of laser radiation with matter. laser plasma)

Recent progress in the modelling of helium and tritium behaviour in irradiated beryllium pebbles

International Nuclear Information System (INIS)

Rabaglino, E.; Ronchi, C.; Cardella, A.

2003-01-01

One of the key issues of the European Helium Cooled Pebble Bed blanket is the behaviour under irradiation of beryllium pebbles, which have the function of neutron multiplier. An intense production of helium occurs in-pile, as well as a non negligible generation of tritium. Helium bubbles induce swelling and a high tritium inventory is a safety issue. Extensive studies for a better understanding, characterisation and modelling of the behaviour of helium and tritium in irradiated beryllium pebbles are being carried out, with the final aim to enable a reliable prediction of gas release and swelling in the full range of operating and accidental conditions of a Fusion Power Reactor. The general strategy consists in integrating studies on macroscopic phenomena (gas release) with the characterisation of corresponding microscopic diffusion phenomena (bubble kinetics) and the assessment of some fundamental diffusion parameter for the models (gas atomic diffusion coefficients). The present work gives a summary of the latest achievements in this context. By an inverse analysis of experimental out-of-pile gas release from weakly irradiated pebbles, coupled to the study of the characteristics of bubble population, it has been possible to assess the thermal diffusion coefficients of helium and tritium in and to improve and validate the classical model of gas precipitation into bubbles inside the grain. The improvement of the description of gas atomic diffusion and precipitation is the first step to enable a more reliable prediction of gas release

A laser optical method for detecting corn kernel defects

Energy Technology Data Exchange (ETDEWEB)

Gunasekaran, S.; Paulsen, M. R.; Shove, G. C.

1984-01-01

An opto-electronic instrument was developed to examine individual corn kernels and detect various kernel defects according to reflectance differences. A low power helium-neon (He-Ne) laser (632.8 nm, red light) was used as the light source in the instrument. Reflectance from good and defective parts of corn kernel surfaces differed by approximately 40%. Broken, chipped, and starch-cracked kernels were detected with nearly 100% accuracy; while surface-split kernels were detected with about 80% accuracy. (author)

Helium diffusion in irradiated boron carbide

International Nuclear Information System (INIS)

Hollenberg, G.W.

1981-03-01

Boron carbide has been internationally adopted as the neutron absorber material in the control and safety rods of large fast breeder reactors. Its relatively large neutron capture cross section at high neutron energies provides sufficient reactivity worth with a minimum of core space. In addition, the commercial availability of boron carbide makes it attractive from a fabrication standpoint. Instrumented irradiation experiments in EBR-II have provided continuous helium release data on boron carbide at a variety of operating temperatures. Although some microstructural and compositional variations were examined in these experiments most of the boron carbide was prototypic of that used in the Fast Flux Test Facility. The density of the boron carbide pellets was approximately 92% of theoretical. The boron carbide pellets were approximately 1.0 cm in diameter and possessed average grain sizes that varied from 8 to 30 μm. Pellet centerline temperatures were continually measured during the irradiation experiments

Helium sequestration at nanoparticle-matrix interfaces in helium + heavy ion irradiated nanostructured ferritic alloys

Energy Technology Data Exchange (ETDEWEB)

Parish, C.M., E-mail: parishcm@ornl.gov [Oak Ridge National Laboratory, Oak Ridge, TN 37831 (United States); Unocic, K.A.; Tan, L. [Oak Ridge National Laboratory, Oak Ridge, TN 37831 (United States); Zinkle, S.J. [Oak Ridge National Laboratory, Oak Ridge, TN 37831 (United States); University of Tennessee, Knoxville, TN 37996 (United States); Kondo, S. [Institute of Advanced Energy, Kyoto University, Uji, Kyoto, 611-0011 (Japan); Snead, L.L. [Massachusetts Institute of Technology, Cambridge, MA 02139 (United States); Hoelzer, D.T.; Katoh, Y. [Oak Ridge National Laboratory, Oak Ridge, TN 37831 (United States)

2017-01-15

We irradiated four ferritic alloys with energetic Fe and He ions: one castable nanostructured alloy (CNA) containing Ti-W-Ta-carbides, and three nanostructured ferritic alloys (NFAs). The NFAs were: 9Cr containing Y-Ti-O nanoclusters, and two Fe-12Cr-5Al NFAs containing Y-Zr-O or Y-Hf-O clusters. All four were subjected to simultaneous dual-beam Fe + He ion implantation (650 °C, ∼50 dpa, ∼15 appm He/dpa), simulating fusion-reactor conditions. Examination using scanning/transmission electron microscopy (STEM) revealed high-number-density helium bubbles of ∼8 nm, ∼10{sup 21} m{sup −3} (CNA), and of ∼3 nm, 10{sup 23} m{sup −3} (NFAs). STEM combined with multivariate statistical analysis data mining suggests that the precipitate-matrix interfaces in all alloys survived ∼50 dpa at 650 °C and serve as effective helium trapping sites. All alloys appear viable structural material candidates for fusion or advanced fission energy systems. Among these developmental alloys the NFAs appear to sequester the helium into smaller bubbles and away from the grain boundaries more effectively than the early-generation CNA.

Chirp analysis of high-order harmonics from atoms driven by intense femtosecond laser pulses

International Nuclear Information System (INIS)

Kim, Hyung Taek; Kim, I Jong; Hong, Kyung-Han; Lee, Dong Gun; Kim, Jung-Hoon; Nam, Chang Hee

2004-01-01

The spectral structure of harmonics was experimentally controlled by changing the chirp of femtosecond laser pulses, and the dependence of harmonic chirp on atomic species was analysed using harmonics from neon and helium. Experimental results and theoretical analysis based on the Wigner distribution function showed that the spectral structure varied sensitively to laser chirp and the harmonic chirp was determined by the competition between dynamically induced negative chirp and self-phase modulation induced positive chirp. The generation of sharp and bright harmonics was achieved with appropriately chirped laser pulses under given experimental conditions, especially negatively chirped pulses in the case of laser intensity above the saturation intensity for optical-field ionization

Mechanical property changes induced in structural alloys by neutron irradiations with different helium to displacement ratios*1

Science.gov (United States)

Mansur, L. K.; Grossbeck, M. L.

1988-07-01

Effects of helium on mechanical properties of irradiated structural materials are reviewed. In particular, variations in response to the ratio of helium to displacement damage serve as the focus. Ductility in creep and tensile tests is emphasized. A variety of early work has led to the current concentration on helium effects for fusion reactor materials applications. A battery of techniques has been developed by which the helium to displacement ratio can be varied. Our main discussion is devoted to the techniques of spectral tailoring and isotopic alloying currently of interest for mixed-spectrum reactors. Theoretical models of physical mechanisms by which helium interacts with displacement damage have been developed in terms of hardening to dislocation motion and grain boundary cavitation. Austenitic stainless steels, ferritic/martensitic steels and vanadium alloys are considered. In each case, work at low strain rates, where the main problems may lie, at the helium to displacement ratios appropriate to fusion reactor materials is lacking. Recent experimental evidence suggests that both in-reactor and high helium results may differ substantially from post-irradiation or low helium results. It is suggested that work in these areas is especially needed.

Time delay between singly and doubly ionizing wavepackets in laser-driven helium

International Nuclear Information System (INIS)

Parker, J S; Doherty, B J S; Meharg, K J; Taylor, K T

2003-01-01

We present calculations of the time delay between single and double ionization of helium, obtained from full-dimensionality numerical integrations of the helium-laser Schroedinger equation. The notion of a quantum mechanical time delay is defined in terms of the interval between correlated bursts of single and double ionization. Calculations are performed at 390 and 780 nm in laser intensities that range from 2 x 10 14 to 14 x 10 14 Wcm -2 . We find results consistent with the rescattering model of double ionization but supporting its classical interpretation only at 780 nm. (letter to the editor)

Cross section for calculating the helium formation rate in construction materials irradiated by nucleons at energies to 800 MeV

International Nuclear Information System (INIS)

Konobeev, A.Yu.; Korovin, Yu.A.

1992-01-01

Recently, effects related to the formation of helium in irradiated construction materials have been studied extensively. Data on the nuclear cross sections for producing helium in these materials form the initial information necessary for such investigations. If the spectrum of the incoming particles is known, the value of the helium production cross section makes it possible to calculate the helium generation rate. In recent years, plans and simulating experiments on radiating materials with high-energy particles made it necessary to determine the helium production cross sections in constructionmaterials, which are irradiated by protons and neutrons with energies to 800 MeV. Helium-formation cross sections have been calculated at these energies. However, a correct description of the experimental data for various construction materials does not yet exist. For example, the calculated helium-formation cross sections turned out to overestimate the experimental data, and to underestimate the experimental data. The objective here is to calculate the helium-formation cross sections for various construction materials, which are irradiated by protons and neutrons to energies from 20 to 800 MeV, and to analyze the probable causes of deviations between experimental and earlier calculated cross sections

In-situ observation of damage evolution in TiC crystals during helium ion irradiation

International Nuclear Information System (INIS)

Hojou, K.; Otsu, H.; Furuno, S.; Izui, K.; Tsukamoto, T.

1994-01-01

In-situ observations were performed on bubble formation and growth in TiC during 20 keV helium ion irradiation over the wide range of irradiation temperatures from 12 to 1523 K. No amorphization occurred over this temperature range. The bubble densities and sizes were almost independent of irradiation temperatures from 12 to 1273 K. Remarkable growth and coalescence occurred during irradiation at high temperature above 1423 K and during annealing above 1373 K after irradiation. ((orig.))

Experimental central nervous system injury after charged-particle irradiation

International Nuclear Information System (INIS)

Rodriguez, A.; Levy, R.P.; Fabrikant, J.I.

1991-01-01

This paper reports on the development of definite paralytic signs, used as an endpoint for the determination of latent periods, which reflect the presence of damage but do not reveal its pathologic characteristics. Paralysis was a nonstochastic effect for which both the probability and severity vary with dose and for which a threshold of dose-response existed. Histologically the primary lesion induced by both charged-particle irradiation and X- or γ-radiation was demyelination and necrosis of the white matter. This has been attributed generally to damage to the oligodendrocytes. The spinal cord tolerance toward fractionated helium radiation was similar to X- or γ-radiation, but the spinal cord was much more sensitive to heavier charged-particle radiation. There was much less sparing and decreased tissue tolerance in the high-LET spread Bragg peak regions of carbon- and neon-ion beams that in the plateau regions. A radiologic model for effects in CNS after charged-particle radiation indicated that the α/β values, a measure of tissue repair capacity, increased with LET as predicted. The α/β values for spinal cord injury with neon range from 2.52 to 12.0 depending on the LET; for helium, the α/β value was 1.52, similar to values for X rays

Low-energy electron-helium scattering in a Nd–YAG laser field

International Nuclear Information System (INIS)

Ajana, I.; Makhoute, A.; Khalil, D.

2014-01-01

Highlights: • Laser assisted electron helium excitation is studied at low incident energies. • The inclusion of the second-order Born contributions is significant at low incident energies. • The target distortion induced by the laser field should be taken into account. • The effect of the second term of the Born series is reduced as the energy increases. - Abstract: We study the electron-impact excitation of atomic helium, in the presence of a linearly polarized Nd–YAG laser field, accompanied by the transfer of ℓ photons, for low collision energy of 25 eV and laser intensity of 5.3 × 10 11 W cm −2 . The second-order Born approximation has been used to calculate the differential cross sections. Detailed calculations of the scattering amplitudes are performed by using the Sturmian basis expansion. A detailed analysis is made of the excitation of the 1 1 S → 2 1 S and 1 1 S → 2 1 P transitions. We discuss the behavior and the variation of the cross sections corresponding to the excitation process for various geometrical configurations

Neovascular glaucoma after helium ion irradiation for uveal melanoma

International Nuclear Information System (INIS)

Kim, M.K.; Char, D.H.; Castro, J.L.; Saunders, W.M.; Chen, G.T.; Stone, R.D.

1986-01-01

Neovascular glaucoma developed in 22 of 169 uveal melanoma patients treated with helium ion irradiation. Most patients had large melanomas; no eyes containing small melanomas developed anterior segment neovascularization. The mean onset of glaucoma was 14.1 months (range, 7-31 months). The incidence of anterior segment neovascularization increased with radiation dosage; there was an approximately three-fold increase at 80 GyE versus 60 GyE of helium ion radiation (23% vs. 8.5%) (P less than 0.05). Neovascular glaucoma occurred more commonly in larger tumors; the incidence was not affected by tumor location, presence of subretinal fluid, nor rate of tumor regression. Fifty-three percent of patients had some response with intraocular pressures of 21 mmHg or less to a combination of antiglaucoma treatments

Study and simulation of the behaviour under irradiation of helium in uranium dioxide; Etude et modelisation du comportement sous irradiation de l'helium dans le dioxyde d'uranium

Energy Technology Data Exchange (ETDEWEB)

Martin, G

2007-06-15

Large quantities of helium are produced from {alpha}-decay of actinides in nuclear fuels during its in-pile operating and its storage. It is important to understand the behaviour of helium in these matrix in order to well simulate the evolution and the resistance of the fuel element. During this thesis, we have used nuclear reaction analyses (NRA) to follow the evolution of the helium implanted in polycrystalline and monocrystalline uranium dioxide (UO{sub 2}). An experimental rig was developed to follow the on-line helium release in UO{sub 2} and the evolution of {sup 3}He profiles as a function of annealing temperature. An automated procedure taking into account the evolution of the depth resolution was developed. Analyses performed with a nuclear microprobe allowed to characterise the spatial distribution of helium at the grain scale and to study the influence of the sample microstructure on the helium migration. This work put into evidence the particular role of grain boundaries and irradiation defects in the helium release process. The analyse of experimental results with a diffusion model corroborates these interpretations. It allowed to determine quantitatively physical properties that characterise the helium behaviour in uranium dioxide (diffusion coefficient, activation energy..). (author)

Positron annihilation in low-temperature rare gases. II. Argon and neon

International Nuclear Information System (INIS)

Canter, K.F.; Roellig, L.O.

1975-01-01

Lifetime measurements of slow-positron and ortho-positronium (o-Ps) annihilation were made in argon and neon gases at room temperature and below. The argon experiments cover the temperature range 115 to 300 0 K and the density range 0.0356 to 0.0726 g/cm 3 (approximately equal to 20 to 40 amagat). The slow-positron spectra in argon exhibit a departure from free-positron annihilation below 200 0 K. The departure becomes more marked as the temperature is lowered. No deviation from free o-Ps pickoff annihilation is observed in argon at low temperatures. The neon measurements cover the temperature range 30 to 300 0 K and the density range 0.032 to 0.89 g/cm 3 (approximately equal to 35 to 980 amagat). No effect of temperature on the slow-positron spectra throughout the temperature and density ranges investigated in neon is observed. The spectra are very exponential with a corresponding decay rate which is temperature as well as time independent and is directly proportional to density over the ranges investigated. The o-Ps data are more eventful in that the o-Ps lifetime at near-liquid densities is approximately 20 nsec, a factor of nearly 4 greater than the value obtained using the pickoff-annihilation coefficient obtained at lower densities. This is evidence for positronium-induced cavities in low-temperature neon. A brief discussion of the argon and neon results is given in the context of the explanations offered for the low-temperature effects observed in helium gas

Reactor irradiation and helium-3 effects on mechanical properties of alpha-titanium alloys

International Nuclear Information System (INIS)

Tebus, V.N.; Alekseev, Eh.F.; Golikov, I.V.

1990-01-01

Dependence of α-titanium alloy mechanical properties on test temperature and neutron fluence is investigated. Irradiation is shown to result in material hardening and in their plasticity reduction, but residual plasticity remains rather high. Additional reduction of plasticity results in helium-3 introduced in materials under irradiation. Restoration of properties is observed at test temperature higher 500 deg C. Irradiation by fast neutrons up to high fluences (1.4·10 23 cm -2 ) results in essential alloy softening

High-order harmonic generation with short-pulse lasers

International Nuclear Information System (INIS)

Schafer, K.J.; Krause, J.L.; Kulander, K.C.

1992-12-01

Recent progress in the understanding of high-order harmonic conversion from atoms and ions exposed to high-intensity, short-pulse optical lasers is reviewed. We find that ions can produce harmonics comparable in strength to those obtained from neutral atoms, and that the emission extends to much higher order. Simple scaling laws for the strength of the harmonic emission and the maximium observable harmonic are suggested. These results imply that the photoemission observed in recent experiments in helium and neon contains contributions from ions as well as neutrals

Helium influence on the microstructure and swelling of 9%Cr ferritic steel after neutron irradiation to 16.3 dpa

International Nuclear Information System (INIS)

Klimenkov, M.; Möslang, A.; Materna-Morris, E.

2014-01-01

Specially fabricated samples of the European reference 9Cr-WTaV steel EUROFER 97 alloyed with 0.081 mass% natural B and 0.081 and 0.114 mass% pure isotope 10 B were neutron-irradiated with about 16.3 dpa at temperatures in the range from 523 K to 723 K to study the influence of helium produced by 10 B(n,α) 7 Li transmutation reaction on microstructure, swelling and hardness. The spatial and size distributions of helium bubbles or cavities after irradiation at different temperatures were investigated by transmission electron microscopy. Vickers microhardness HV0.1 tests were performed on the as received specimens and specimens after irradiation. The influence of irradiation temperature and helium concentration on the size and density of the bubbles or cavities was analyzed and correlations with the hardness, tensile properties, and the fracture surface were discussed

Convoluted dislocation loops induced by helium irradiation in reduced-activation martensitic steel and their impact on mechanical properties

Energy Technology Data Exchange (ETDEWEB)

Luo, Fengfeng [Key Laboratory of Artificial Micro- and Nano-structures of Ministry of Education, Hubei Nuclear Solid Physics Key Laboratory, School of Physics and Technology, Wuhan University, Wuhan 430072 (China); Yao, Z. [Department of Mechanical and Materials Engineering, Queen' s University, Kingston, ON, Canada K7L 3N6 (Canada); Guo, Liping, E-mail: guolp@whu.edu.cn [Key Laboratory of Artificial Micro- and Nano-structures of Ministry of Education, Hubei Nuclear Solid Physics Key Laboratory, School of Physics and Technology, Wuhan University, Wuhan 430072 (China); Suo, Jinping [State Key Laboratory of Mould Technology, Institute of Materials Science and Engineering, Huazhong University of Science and Technology, Wuhan 430074 (China); Wen, Yongming [Key Laboratory of Artificial Micro- and Nano-structures of Ministry of Education, Hubei Nuclear Solid Physics Key Laboratory, School of Physics and Technology, Wuhan University, Wuhan 430072 (China)

2014-06-01

Helium irradiation induced dislocation loops in reduced-activation martensitic steels were investigated using transmission electron microscopy. The specimens were irradiated with 100 keV helium ions to 0.8 dpa at 350 °C. Unexpectedly, very large dislocation loops were found, significantly larger than that induced by other types of irradiations under the same dose. Moreover, the large loops were convoluted and formed interesting flower-like shape. The large loops were determined as interstitial type. Loops with the Burgers vectors of b=〈100〉 were only observed. Furthermore, irradiation induced hardening caused by these large loops was observed using the nano-indentation technique.

Positronium formation in helium bubbles in 600 MeV proton-irradiated aluminium

DEFF Research Database (Denmark)

Jensen, K. O.; Eldrup, Morten Mostgaard; Singh, Bachu Narain

1985-01-01

Aluminium samples containing helium bubbles produced by 600 MeV proton irradiation at 430°C were investigated by positron annihilation; both lifetime and angular correlation measurements were made. The angular correlation curves contain an unusually narrow component. This component is associated...

Krypton and helium irradiation damage in neodymium-zirconolite

International Nuclear Information System (INIS)

Gilbert, M.; Davoisne, C.; Stennett, M.; Hyatt, N.; Peng, N.; Jeynes, C.; Lee, W.E.

2011-01-01

A leading candidate for the immobilisation of actinides, zirconolite's suitability as a potential ceramic host for plutonium disposition, both in storage and geological disposal, has been the subject of much research. One key aim of this study is to understand the effects of radiation damage and noble gas accommodation within the zirconolite material. To this end, a series of ex situ irradiations have been performed on polycrystalline (Ca 0.8 Nd 0.2 )Zr(Ti 1.8 Al 0.2 )O 7 zirconolite samples. Zirconolite samples, doped with Nd 3+ (as a Pu surrogate) on the Ca-site and charge-balanced by substituting Al 3+ onto the Ti-site, were irradiated with 36 Kr + (2 MeV) ions at fluences of 1 x 10 14 and 5 x 10 15 cm -2 and 4 He + (200 keV) ions at fluences of 1 x 10 14 , 5 x 10 15 and 1 x 10 17 cm -2 to simulate the impact of alpha decay on the microstructure. Microstructural analysis revealed no damage present at the lower Kr + fluence, but that the higher 36 Kr + fluence rendered the zirconolite completely amorphous. Similarly, evidence of helium accumulation was only seen at the highest 4 He + fluence (1 x 10 17 cm -2 ). Monte Carlo simulations using the TRIM code predict the highest concentration of helium accumulating at a depth of 720 nm, in good agreement with the experimental observations.

Impulsive Laser Induced Alignment of Molecules Dissolved in Helium Nanodroplets

DEFF Research Database (Denmark)

Pentlehner, Dominik; H. Nielsen, Jens; Slenczka, Alkwin

2013-01-01

We show that a 450 fs nonresonant, moderately intense, linearly polarized laser pulse can induce field-free molecular axis alignment of methyliodide (CH3I) molecules dissolved in a helium nanodroplet. Time-resolved measurements reveal rotational dynamics much slower than that of isolated molecules...

Effect of preliminary neutron irradiation on helium blistering of 0Kh16N15M3B steel

International Nuclear Information System (INIS)

Chernov, I.I.; Kalin, B.A.; Skorov, D.M.; Shishkin, G.N.; Ivanov, M.V.

1982-01-01

The method of electron microscopy has been applied to investigate the effect of preliminary neutron irradiation on the OKh16N15M3B steel blistering under irradiation by 20 keV helium ions with (1-10)x10 21 ion/m 2 doses at the temperature below 373 K. It is shown that neutron irradiation shifts critical doses of blister formation and intense scaling towards higher doses. But after the incubation period the erosion of steel preliminary neutron irradiated grows with the increase of helium ion dose above 7x10 21 ion/m 2 . Short-term heating of neutron irradiated samples during 15 min at 1173 K does not practically affect the beginning of intense scaling of the surface

The effect of helium, radiation damage and irradiation temperature on the mechanical properties of beryllium

Energy Technology Data Exchange (ETDEWEB)

Fabritsiev, S.A. [D.V. Efremov Scientific Research Inst., St. Petersburg (Russian Federation); Pokrovsky, A.S.

1998-01-01

In this work different RF beryllium grades were irradiated in the BOR-60 reactor to a dose of {approx}5-10 dpa at irradiation temperatures 350, 420, 500, 800degC. Irradiation at temperatures of 350-400degC is shown to result in Be hardening due to the accumulation of radiation defect complexes. Hardening is accompanied with a sharp drop in plasticity at T{sub test} {<=} 300degC. A strong anisotropy in plasticity has been found at a mechanical testing temperature of 400degC and this parameter may be preferable when the samples are cut crosswise to the pressing direction. High-temperature irradiation (T{sub irr} = 780degC) gives rise to large helium pores over the grain boundaries and smaller pores in the grain body. Fracture is brittle and intercrystallite at T{sub test} {>=} 600degC. Helium embrittlement is accompanied as well with a drop in the Be strength properties. (author)

Novel CO2 laser robotic controller outperforms experienced laser operators in tasks of accuracy and performance repeatability.

Science.gov (United States)

Wong, Yu-Tung; Finley, Charles C; Giallo, Joseph F; Buckmire, Robert A

2011-08-01

To introduce a novel method of combining robotics and the CO(2) laser micromanipulator to provide excellent precision and performance repeatability designed for surgical applications. Pilot feasibility study. We developed a portable robotic controller that appends to a standard CO(2) laser micromanipulator. The robotic accuracy and laser beam path repeatability were compared to six experienced users of the industry standard micromanipulator performing the same simulated surgical tasks. Helium-neon laser beam video tracking techniques were employed. The robotic controller demonstrated superiority over experienced human manual micromanipulator control in accuracy (laser path within 1 mm of idealized centerline), 97.42% (standard deviation [SD] 2.65%), versus 85.11% (SD 14.51%), P = .018; and laser beam path repeatability (area of laser path divergence on successive trials), 21.42 mm(2) (SD 4.35 mm(2) ) versus 65.84 mm(2) (SD 11.93 mm(2) ), P = .006. Robotic micromanipulator control enhances accuracy and repeatability for specific laser tasks. Computerized control opens opportunity for alternative user interfaces and additional safety features. Copyright © 2011 The American Laryngological, Rhinological, and Otological Society, Inc.

Charge collection in Si detectors irradiated in situ at superfluid helium temperature

Energy Technology Data Exchange (ETDEWEB)

Verbitskaya, Elena, E-mail: elena.verbitskaya@cern.ch [Ioffe Institute, 26 Politekhnicheskaya str., St. Petersburg 194021 (Russian Federation); Eremin, Vladimir; Zabrodskii, Andrei [Ioffe Institute, 26 Politekhnicheskaya str., St. Petersburg 194021 (Russian Federation); Dehning, Bernd; Kurfürst, Christoph; Sapinski, Mariusz; Bartosik, Marcin R. [CERN, CH-1211, Geneva 23 (Switzerland); Egorov, Nicolai [Research Institute of Material Science and Technology, 4 Passage 4806, Moscow, Zelenograd 124460 (Russian Federation); Härkönen, Jaakko [Helsinki Institute of Physics, P.O.Box 64 (Gustaf Hallströmin katu 2) FI-00014 University of Helsinki (Finland)

2015-10-01

Silicon and diamond detectors operated in a superfluid helium bath are currently being considered for the upgrade of the LHC beam loss monitoring system. The detectors would be installed in immediate proximity of the superconducting coils of the triplet magnets. We present here the results of the in situ irradiation test for silicon detectors using 23 GeV protons while keeping the detectors at a temperature of 1.9 K. Red laser (630 nm) Transient Current Technique and DC current measurements were used to study the pulse response and collected charge for silicon detectors irradiated to a maximum radiation fluence of 1×10{sup 16} p/cm{sup 2}. The dependence between collected charge and irradiation fluence was parameterized using the Hecht equation and assumption of a uniform electric field distribution. The collected charge was found to degrade with particle fluence for both bias polarities. We observed that the main factor responsible for this degradation was related to trapping of holes on the donor-type radiation-induced defects. In contrast to expectations, along with formation of donors, acceptor-type defects (electron traps) are introduced into the silicon bulk. This suggests that the current models describing charge collection in irradiated silicon detectors require an extension for taking into account trapping at low temperatures with a contribution of shallow levels. New in situ irradiation tests are needed and planned now to extend statistics of the results and gain a deeper insight into the physics of low temperature detector operation in harsh radiation environment. - Highlights: • Si detectors irradiated in situ at 1.9 K by 23 GeV protons are further studied. • Trapping parameters are derived from the fits of collected charge vs. fluence data. • Acceptor-type defects are likely to be induced along with donor-type ones. • Trapping of holes has a dominating effect on the collected charge degradation. • New tests are planned to gain deeper insight

Influence of Er:YAG and Nd:YAG wavelengths on laser-induced breakdown spectroscopy measurements under air or helium atmosphere

International Nuclear Information System (INIS)

Detalle, Vincent; Sabsabi, Mohamad; St-Onge, Louis; Hamel, Andre; Heon, Rene

2003-01-01

Laser-induced breakdown spectroscopy (LIBS) is widely dependent on the conditions of its implementation in terms of laser characteristics (wavelength, energy, and pulse duration), focusing conditions, and surrounding gas. In this study two wavelengths, 1.06 and 2.94 μm, obtained with Nd:YAG and Er:YAG lasers, respectively, were used for LIBS analysis of aluminum alloy samples in two conditions of surrounding gas. The influence of the laser wavelength on the laser-produced plasma was studied for the same irradiance by use of air or helium as a buffer gas at atmospheric pressure. We used measurements of light emission to determine the temporally resolved space-averaged electron density and plasma temperature in the laser-induced plasma. We also examined the effect of laser wavelength in two different ambient conditions in terms of spectrochemical analysis by LIBS. The results indicate that the effect of the surrounding gas depends on the laser wavelength and the use of an Er:YAG laser could increase linearity by limiting the leveling in the calibration curve for some elements in aluminum alloys. There is also a significant difference between the plasma induced by the two lasers in terms of electron density and plasma temperature

Influence of tensile stress on cavity growth in nickel under helium irradiation

International Nuclear Information System (INIS)

Kusanagi, Hideo; Hide, Koichiro; Takaku, Hiroshi

1989-01-01

The influence of tensile stress on cavity behavior in pure nickel under helium irradiation was investigated by in-situ observation using the transmission electron microscope (TEM) in which an ion gun is installed. Specimens were irradiated at 500 0 C with 20 keV helium in the TEM. The dose rate was about 10 14 He/cm 2 s, and the angle between the helium beam and the normal direction of the specimens was about 60 0 . The damage rate estimated by the E-DEP-1 code was about 0.6x10 -3 dpa/s at its peak position. The main results are as follows: (1) cavity nucleation was accelerated by applying tensile stress, and cavity size in stressed specimens was several times larger than that in stress-free specimens; (2) cavity density in the stressed specimen increased more rapidly than in the stress-free specimen, and then decreased by cavity coalescences; (3) depth of cavity nucleation in the stress-free specimen was about 160 nm, while that in the stressed specimen was about 320 nm; that is, cavities nucleated in deeper regions in the stressed specimen than in the stress-free specimen. This result indicates that helium atoms and vacancies can migrate into the deeper region by applying tensile stress. (4) The experimental results obtained in this study can be explained qualitatively by the mechanism that mobile dislocations drag He-V complexes to the deeper region. This implies that there are similar phenomena in the case of compressive stress. (orig.)

Laser puncture therapy of nervous system disorders

Energy Technology Data Exchange (ETDEWEB)

Anishchenko, G.; Kochetkov, V.

1984-08-29

The authors discuss experience with treatment of nervous system disorders by means of laser-puncture therapy. Commenting on the background of the selection of this type of treatment, they explain that once researchers determined the biological action of laser light on specific nerve receptors of the skin, development of laser apparatus capable of concentrating the beam in the millimeter band was undertaken. The devices that are being used for laser-puncture are said to operate in the red helium-neon band of light. The authors identify beam parameters that have been selected for different groups of acupuncture points of the skin, and the courses of treatment (in seconds of radiation) and their time intervals. They go on to discuss the results of treatment of over 800 patients categorized in a group with disorders of the peripheral nervous system and a second group with disorders of the central nervous system.

Scaling of the helium--nitrogen charge transfer laser

International Nuclear Information System (INIS)

Collins, C.B.; Cunningham, A.J.

1975-01-01

The scaling to high powers of the nitrogen ion laser pumped by charge transfer from He + 2 is reported. Intense emission has been found from three laser lines at 3914, 4278, and 4709 A upon discharge of a fast-pulsed electron beam gun, APEX-1, into several atmospheres of a mixture of helium and nitrogen. Excitation current densities were 1.3 kA/cm 2 at 1 MV over a 1times10-cm transverse geometry. The efficiency of the 4278-A laser emission was found to be proportional to the total pressure raised to the 1.2 power. Outputs of 36 mJ have been obtained from the 16-cm 3 working volume at 30-atm pressure and a peak efficiency of 1.6% relative to the energy lost by the electron beam in this radiating volume has been achieved

Tritium-doping enhancement of polystyrene by ultraviolet laser and hydrogen plasma irradiation for laser fusion experiments

Energy Technology Data Exchange (ETDEWEB)

Iwasa, Yuki, E-mail: iwasa-y@ile.osaka-u.ac.jp [Institute of Laser Engineering, Osaka University, 2-6 Yamadaoka, Suita, Osaka 565-0871 (Japan); Yamanoi, Kohei; Iwano, Keisuke; Empizo, Melvin John F.; Arikawa, Yasunobu; Fujioka, Shinsuke; Sarukura, Nobuhiko; Shiraga, Hiroyuki; Takagi, Masaru; Norimatsu, Takayoshi; Azechi, Hiroshi [Institute of Laser Engineering, Osaka University, 2-6 Yamadaoka, Suita, Osaka 565-0871 (Japan); Noborio, Kazuyuki; Hara, Masanori; Matsuyama, Masao [Hydrogen Isotope Research Center, Organization for Promotion of Research, University of Toyama, 3190 Gofuku, Toyama 930-8555 (Japan)

2016-11-15

Highlights: • Tritium-doped polystyrene films are fabricated by the Wilzbach method with UV laser and hydrogen plasma irradiation. • The 266-nm laser-irradiated, 355-nm laser-irradiated, and hydrogen plasma-irradiated polystyrene films exhibit higher PSL intensities and specific radioactivities than the non-irradiated sample. • Tritium doping by UV laser irradiation can be largely affected by the laser wavelength because of polystyrene’s absorption. • Hydrogen plasma irradiation results to a more uniform doping concentration even at low partial pressure and short irradiation time. • UV laser and plasma irradiations can be utilized to fabricate tritium-doped polystyrene shell targets for future laser fusion experiments. - Abstract: We investigate the tritium-doping enhancement of polystyrene by ultraviolet (UV) laser and hydrogen plasma irradiation. Tritium-doped polystyrene films are fabricated by the Wilzbach method with UV laser and hydrogen plasma. The 266-nm laser-irradiated, 355-nm laser-irradiated, and hydrogen plasma-irradiated polystyrene films exhibit higher PSL intensities and specific radioactivities than the non-irradiated sample. Tritium doping by UV laser irradiation can be largely affected by the laser wavelength because of polystyrene’s absorption. In addition, UV laser irradiation is more localized and concentrated at the spot of laser irradiation, while hydrogen plasma irradiation results to a more uniform doping concentration even at low partial pressure and short irradiation time. Both UV laser and plasma irradiations can nevertheless be utilized to fabricate tritium-doped polystyrene targets for future laser fusion experiments. With a high doping rate and efficiency, a 1% tritium-doped polystyrene shell target having 7.6 × 10{sup 11} Bq g{sup −1} specific radioactivity can be obtained at a short period of time thereby decreasing tritium consumption and safety management costs.

Retention of neon in graphite after ion beam implantation or exposures to the scrape-off layer plasma in the TEXTOR tokamak

International Nuclear Information System (INIS)

Kim, Y.M.; Philipps, V.; Rubel, M.; Vietzke, E.; Pospieszczyk, A.; Unterberg, B.; Jaspers, R.

2002-01-01

The interaction of neon ions with graphite was investigated for targets either irradiated with ion beams (2-10 keV range) or exposed to the scrape-off layer plasma in the TEXTOR tokamak during discharges with neon edge cooling. The emphasis was on the influence of the target temperature (300-1200 K) and the implantation dose on the neon retention and reemission. The influence of deuterium impact on the retention of neon implanted into graphite has also been addressed. In ion beam experiments saturation is observed above a certain ion dose with a saturation level, which decreases with increasing target temperature. The temperature dependence of the thermal desorption corresponds to an apparent binding energy of about 2.06 eV. The retention of neon (C Ne /C C ) decreases with increasing ion energy with values from 0.55 to 0.15 following irradiation with 2 and 10 keV ions, respectively. The reemission yield during the irradiation increases with target temperature and above 1200 K all impinging ions are reemitted instantaneously. The retention densities measured using the sniffer probe at the TEXTOR tokamak are less than 1% of the total neon fluence and are over one order of magnitude smaller than those observed in ion beam experiments. The results are discussed in terms of different process decisive for ion deposition and release under the two experimental conditions

Laser scanning of experimental solar cells

Science.gov (United States)

Plunkett, B. C.; Lasswell, P. G.

1980-01-01

A description is presented of a laser scanning instrument which makes it possible to display and measure the spatial response of a solar cell. Examples are presented to illustrate the use of generated micrographs in the isolation of flaws and features of the cell. The laser scanner system uses a 4 mW, CW helium-neon laser, operating a wavelength of 0.633 micrometers. The beam is deflected by two mirror galvanometers arranged to scan in orthogonal directions. After being focused on the solar cell by the beam focusing lens, the moving light spot raster scans the specimen. The current output of the photovoltaic device under test, as a function of the scan dot position, can be displayed in several modes. The laser scanner has proved to be a very useful diagnostic tool in optimizing the process design of transparent metal film photovoltaic devices on Zn3P2, a relatively new photovoltaic material.

Morphological and spectroscopic characterization of laser-ablated tungsten at various laser irradiances

Energy Technology Data Exchange (ETDEWEB)

Akram, Mahreen; Bashir, Shazia; Hayat, Asma; Mahmood, Khaliq; Dawood, Asadullah [Government College University, Centre for Advanced Studies in Physics, Lahore (Pakistan); Rafique, Muhammad Shahid [University of Engineering and Technology, Department of Physics, Lahore (Pakistan); Bashir, M.F. [COMSATS Institute of Information Technology, Department of Physics, Lahore (Pakistan)

2015-06-15

The variation in surface morphology and plasma parameters of laser irradiated tungsten has been investigated as a function of irradiance. For this purpose, Nd:YAG laser (1064 nm, 10 ns, 10 Hz) is employed. Tungsten targets were exposed to various laser irradiances ranging from 6 to 50 GW/cm{sup 2} under ambient environment of argon at a pressure of 20 Torr. Scanning electron microscope analysis has been performed to analyze the surface modification of irradiated tungsten. It revealed the formation of micro- and nanoscale surface structures. In central ablated area, distinct grains and crack formation are observed, whereas peripheral ablated areas are dominated by cones and pinhole formation. It was observed that at irradiances exceeding a value of 13 GW/cm{sup 2}, the morphological trend of the observed structures has been changed from erosion to melting and re-deposition dominant phase. Ablation efficiency as a function of laser irradiance has also been investigated by measuring the crater depth using surface profilometry analysis. It is found to be maximum at an irradiance of 13 GW/cm{sup 2} and decreases at high laser irradiances. In order to correlate the accumulated effects of plasma parameters with the surface modification, laser-induced breakdown spectroscopy analysis has been performed. The electron temperature and number density of tungsten plasma have been evaluated at various laser irradiances. Initially with the increase of the laser irradiance up to 13 GW/cm{sup 2}, an increasing trend is observed for both plasma parameters due to enhanced energy deposition. Afterward, a decreasing trend is achieved which is attributed to the shielding effect. With further increase in irradiance, a saturation stage comes and insignificant changes are observed in plasma parameters. This saturation is explainable on the basis of the formation of a self-regulating regime near the target surface. Surface modifications of laser irradiated tungsten have been correlated with

Setting-up of the Laser Induced Fluorescence diagnostic. Measurements of Cr density in a neon glow discharge; Puesta a punto del diagnstico de fluorescencia inducida por laser. Medidas de densidad de Cr en Glow discharg de Neon

Energy Technology Data Exchange (ETDEWEB)

Tafalla, D.; Cal, E. de la; Tabares, F. L.

1994-07-01

A plasma diagnostic based on the Laser Induced Fluorescence (LIF) technique has been set up in the Fusion Division at the CIEMAT. In a preliminary experiment, the density of sputtered chromium atoms produced in a neon glow discharge was measured. Firstly, the laser beam was characterized by calibration of its wavelength, bandwidth and energy profile and Rayleigh scattering in N2 was used for the optical system calibration. An absolute density of Cr atoms of n {approx} 5x10 cm was obtained in discharges at 100 mA and pressure of 15 mTorr and a linear dependence of the LIF signal us. current was found. These values are in agreement with those expected from the tabulated sputtering yields and the thermalization and diffusion of the sputtered atoms into the Ne plasma. (Author) 19 refs.

Multiple pulse traveling wave excitation of neon-like germanium

International Nuclear Information System (INIS)

Moreno, J. C.; Nilsen, J.; Silva, L. B. da

1995-01-01

Traveling wave excitation has been shown to significantly increase the output intensity of the neon-like germanium x-ray laser. The driving laser pulse consisted of three 100 ps Gaussian laser pulses separated by 400 ps. Traveling wave excitation was employed by tilting the wave front of the driving laser by 45 degrees to match the propagation speed of the x-ray laser photons along the length of the target. We show results of experiments with the traveling wave, with no traveling wave, and against the traveling wave and comparisons to a numerical model. Gain was inferred from line intensity measurements at two lengths

Setting-up of the Laser Induced Fluorescence diagnostic. Measurements of Cr density in a neon glow discharge

International Nuclear Information System (INIS)

Tafalla, D.; Cal, E. de la; Tabares, F.L.

1994-01-01

A plasma diagnostic based on the Laser Induced Fluorescence (LIF) technique has been set up in the Fusion Division at the CIEMAT. In a preliminary experiment, The density of sputtered chromium atoms produced in a neon glow discharge was measured. Firstly, the laser beam was characterized by calibration of its wavelength bandwidth and energy profile and Rayleigh scattering in N 2 was used for the optical system calibration. An absolute density of Cr atoms of n= 5x10''9 cm''-3 was obtained in discharges at 100 mA and pressure of 15 mTorr and a linear dependence of the LIF signal US. current was found. These values are in agreement with those expected from the tabulated sputtering yields and the thermalization and diffusion of the sputtered atoms into the Ne plasma

Irradiation damage in boron carbide: point defects, clusters and helium bubbles

International Nuclear Information System (INIS)

Stoto, T.; Zuppiroli, L.

1986-06-01

Boron carbide is a refractory hard and light material of interest in nuclear technology (fission and also fusion). Transmission electron microscopy was used to examine the properties of radiation induced damage. Firstly, the production of point defects and their clustering was studied in samples irradiated by 1 MeV electron in a high voltage electron microscope at selected temperatures from 12 K to 1000 K. Secondly, conventional transmission electron microscopy was used to understand the production of helium bubbles in neutron irradiated boron carbide and their role in the generation of microcracks. Finally, the interaction between point defects and bubbles was also examined

Improvement of laser irradiation uniformity in GEKKO XII glass laser system

International Nuclear Information System (INIS)

Miyanaga, Noriaki; Matsuoka, Shinichi; Ando, Akinobu; Amano, Shinji; Nakatsuka, Masahiro; Kanabe, Tadashi; Jitsuno, Takahisa; Nakai, Sadao

1995-01-01

The uniform laser irradiation is one of key issues in the direct drive laser fusion research. The several key technologies for the uniform laser irradiation are reported. This paper includes the uniformity performance as a result of the introduction of the random phase plate, the partially coherent light and the beam smoothing by spectral dispersion into the New Gekko XI glass laser system. Finally the authors summarize the overall irradiation uniformity on the spherical target surface by considering the power imbalance effect. The technologies developed for the beam smoothing and the power balance control enable them to achieve the irradiation nonuniformities of around 1% level for a foot pulse and of a few % for a main drive pulse, respectively

Fatigue behavior of type 316 stainless steel following neutron irradiation inducing helium

International Nuclear Information System (INIS)

Grossbeck, M.L.; Liu, K.C.

1980-01-01

Since a tokamak fusion reactor operates in a cyclic mode, thermal stresses will result in fatigue in structural components, especially the first wall and blanket. Type 316 stainless steel in the 20% cold-worked condition has been irradiated in the HFIR in order to introduce helium as well as displacement damage. A miniature hourglass specimen was developed for the reactor irradiations and subsequent fully reversed low cycle fatigue testing. For material irradiated and tested at 430 0 C in vacuum to a damage level of 7 to 15 dpa and containing 200 to 1000 appm He, a reduction in life by a factor of 3 to 10 was observed. An attempt was made to predict irradiated fatigue life by fitting data from irradiated material to a power law equation similar to the universal slopes equation and using ductility ratios from tensile tests to modify the equation for irradiated material

Fine Structure in Helium-like Fluorine by Fast-Beam Laser Spectroscopy

Science.gov (United States)

Myers, E. G.; Thompson, J. K.; Silver, J. D.

1998-05-01

With the aim of providing an additional precise test of higher-order corrections to high precision calculations of fine structure in helium and helium-like ions(T. Zhang, Z.-C. Yan and G.W.F. Drake, Phys. Rev. Lett. 77), 1715 (1996)., a measurement of the 2^3P_2,F - 2^3P_1,F' fine structure in ^19F^7+ is in progress. The method involves doppler-tuned laser spectroscopy using a CO2 laser on a foil-stripped fluorine ion beam. We aim to achieve a higher precision, compared to an earlier measurement(E.G. Myers, P. Kuske, H.J. Andrae, I.A. Armour, H.A. Klein, J.D. Silver, and E. Traebert, Phys. Rev. Lett. 47), 87 (1981)., by using laser beams parallel and anti-parallel to the ion beam, to obtain partial cancellation of the doppler shift(J.K. Thompson, D.J.H. Howie and E.G. Myers, Phys. Rev. A 57), 180 (1998).. A calculation of the hyperfine structure, allowing for relativistic, QED and nuclear size effects, will be required to obtain the ``hyperfine-free'' fine structure interval from the measurements.

First observation of laser-induced resonant annihilation in metastable antiprotonic helium atoms

International Nuclear Information System (INIS)

Morita, N.; Kumakura, M.; Yamazaki, T.

1993-11-01

We have observed the first laser-induced resonant transitions in antiprotonic helium atoms. These occur between metastable states and Auger dominated short lived states, and show that the anomalous longevity of antiprotons previously observed in helium media results from the formation of high-n high-l atomic states of p-barHe + . The observed transition with vacuum wavelength 597.259 ± 0.002 nm and lower-state lifetime 15 ± 1 ns is tentatively assigned to (n,l) = (39,35) → (38,34). (author)

Tensile properties and microstructure of helium injected and reactor irradiated V-20 Ti

International Nuclear Information System (INIS)

Tanaka, M.P.; Bloom, E.E.; Horak, J.A.

1980-01-01

The objective of this work was to determine the effect of preinjected helium followed by neutron irradiation on the mechanical properties and microstructure of V-20% Ti. These results will be used for the evaluation of the potential use of V-20% Ti in fusion reactor service

The reaction of unirradiated and irradiated nuclear graphites with water vapor in helium

International Nuclear Information System (INIS)

Imai, Hisashi; Nomura, Shinzo; Kurosawa, Takeshi; Fujii, Kimio; Sasaki, Yasuichi

1980-10-01

Nuclear graphites more than 10 brands were oxidized with water vapor in helium and then some selected graphites were irradiated with fast neutron in the Japan Materials Testing Reactor to clarify the effect of radiation damage of graphite on their reaction behaviors. The reaction was carried out under a well defined condition in the temperature range 800 -- 1000 0 C at concentrations of water vapor 0.38 -- 1.30 volume percent in helium flow of total pressure of 1 atm. The chemical reactivity of graphite irradiated at 1000 +- 50 0 C increased linearly with neutron fluence until irradiation of 3.2 x 10 21 n/cm 2 . The activation energy for the reaction was found to decrease with neutron fluence for almost all the graphites, except for a few ones. The order of reaction increased from 0.5 for the unirradiated graphite to 1.0 for the graphite irradiated up to 6.0 x 10 20 n/cm 2 . Experiment was also performed to study a superposed effect between the influence of radiation damage of graphite and the catalytic action of barium on the reaction rate, as well as the effect of catalyser of barium. It was shown that these effects were not superposed upon each other, although barium had a strong catalytic action on the reaction. (author)

Setting-up of the Laser Induced Fluorescence diagnostic. Measurements of Cr density in a neon glow discharge

International Nuclear Information System (INIS)

Tafalla, D.; Cal, E. de la; Tabares, F. L.

1994-01-01

A plasma diagnostic based on the Laser Induced Fluorescence (LIF) technique has been set up in the Fusion Division at the CIEMAT. In a preliminary experiment, the density of sputtered chromium atoms produced in a neon glow discharge was measured. Firstly, the laser beam was characterized by calibration of its wavelength, bandwidth and energy profile and Rayleigh scattering in N2 was used for the optical system calibration. An absolute density of Cr atoms of n ∼ 5x10 cm was obtained in discharges at 100 mA and pressure of 15 mTorr and a linear dependence of the LIF signal us. current was found. These values are in agreement with those expected from the tabulated sputtering yields and the thermalization and diffusion of the sputtered atoms into the Ne plasma. (Author) 19 refs

Laser irradiation of carbon–tungsten materials

International Nuclear Information System (INIS)

Marcu, A; Lungu, C P; Ursescu, D; Porosnicu, C; Grigoriu, C; Avotina, L; Kizane, G; Marin, A; Osiceanu, P; Grigorescu, C E A; Demitri, N

2014-01-01

Carbon–tungsten layers deposited on graphite by thermionic vacuum arc (TVA) were directly irradiated with a femtosecond terawatt laser. The morphological and structural changes produced in the irradiated area by different numbers of pulses were systematically explored, both along the spots and in their depths. Although micro-Raman and Synchrotron-x-ray diffraction investigations have shown no carbide formation, they have shown the unexpected presence of embedded nano-diamonds in the areas irradiated with high fluencies. Scanning electron microscopy images show a cumulative effect of the laser pulses on the morphology through the ablation process. The micro-Raman spatial mapping signalled an increased percentage of sp 3 carbon bonding in the areas irradiated with laser fluencies around the ablation threshold. In-depth x-ray photoelectron spectroscopy investigations suggested a weak cumulative effect on the percentage increase of the sp 2 -sp 3 transitions with the number of laser pulses just for nanometric layer thicknesses. (paper)

Excitation and ionization of hydrogen and helium atoms by femtosecond laser pulses: theoretical approach by Coulomb-Volkov states; Excitation et ionisation des atomes d'hydrogene et d'helium par des impulsions laser femtosecondes: approche theorique par des etats de Coulomb-Volkov

Energy Technology Data Exchange (ETDEWEB)

Guichard, R

2007-12-15

We present a theoretical approach using Coulomb-Volkov states that appears useful for the study of atomic multi-photonic processes induced by intense XUV femtosecond laser pulses. It predicts hydrogen ionization spectra when it is irradiated by laser pulses in perturbations conditions. Three ways have been investigated. Extension to strong fields when {Dirac_h}{omega} > I{sub p}: it requires to include the hydrogen ground state population, introducing it in standard Coulomb-Volkov amplitude leads to saturated multi-photonic ionization. Extension to multi-photonic transitions with {Dirac_h}{omega} < I{sub p}: new quantum paths are open by the possibility to excite the lower hydrogen bound states. Multiphoton excitation of these states is investigated using a Coulomb-Volkov approach. Extension to helium: two-photon double ionization study shows the influence of electronic correlations in both ground and final state. Huge quantity of information such as angular and energetic distributions as well as total cross sections is available. (author)

Effect of UV laser irradiation on tissue

International Nuclear Information System (INIS)

Nakayama, Takeyoshi; Kubo, Uichi

1992-01-01

Laser-tissue interactions have been investigated through Electron Probe Micro Analysis (EPMA), UV-visible optical absorption and Fourier Transform Infrared Spectroscopy (FTIR). Three excimer lasers, ArF, KrF and XeCl, were used to irradiate tissue; cow thighbone and gelatin thin film. Features of UV laser irradiation are described. (author)

Induratio penis plastica (IPP) and laser: a review

Science.gov (United States)

Longo, Leonardo; Mancini, S.; Postiglione, M. G.

2002-10-01

The first employments of Laser therapy for I.P.P. came from back to more than twenty years ago. At the beginning it was employed only in the acute forms as analgesic laser laser was used also as anti-inflammatory following the doses of Low Level Laser Therapy. Than the science tried to use the laser effect remodelling phase of the scars, to make the fibrosis regrade in the chronic forms. Tunable laser in small optical fiber was used for ablation of calcified zones with very good results. For the slight forms were used diode laser 660 and 904 nm, alone ir coupling with CO2 laser with large spot. At first some Author used helium-Neon laser 632. Some of these lasers were combined wtih microiontophoresis and ultrasounds therapy in teh same treatment. Now we use 810 nm surgical diode laser in almost all induratio forms. The immediate results and follow up will be discussed. Thanks to these results we could conclude that IPP laser therapy can be effective in most of the clinic forms. Although the used procedure is subject to improvement.

Associative ionization of neon and helium atoms by collisions of excited helium (31p) atoms of thermal energies

International Nuclear Information System (INIS)

Runge, Serge.

1980-12-01

The relative cross-sections of ionizing collisions between He + He and He + Ne atoms, have been studied, the helium being excited in a state (3 1 p) by a laser beam. The results obtained made it possible (a) to reveal in a direct manner the production of molecular ions He 2 + and He Ne + and (b) to determine the relative change in the associative ionizing cross-section in the area (0.035 - 0.17 eV) in the He (3 1 P) + Ne collision, despite the very short life of the He (3 1 P) excited state (1.7 ns). The production of He 2 + ions from an He (3 1 P) + He collision sets an upper limit to the appearance potential of these ions. The experimental study of the associative ionization in the He (3 1 P) + Ne system made it possible to extend the utilization of the GAMMA(R) self ionization model, already tested for the metastable states, to the radiative states. The GAMMA(R) model seems well suited for the description of collisions of the A excited + B type, where the excitation energy of A is greater than the ionization potential of B [fr

Excitation and ionization of hydrogen and helium atoms by femtosecond laser pulses: theoretical approach by Coulomb-Volkov states

International Nuclear Information System (INIS)

Guichard, R.

2007-12-01

We present a theoretical approach using Coulomb-Volkov states that appears useful for the study of atomic multi-photonic processes induced by intense XUV femtosecond laser pulses. It predicts hydrogen ionization spectra when it is irradiated by laser pulses in perturbations conditions. Three ways have been investigated. Extension to strong fields when ℎω > I p : it requires to include the hydrogen ground state population, introducing it in standard Coulomb-Volkov amplitude leads to saturated multi-photonic ionization. Extension to multi-photonic transitions with ℎω p : new quantum paths are open by the possibility to excite the lower hydrogen bound states. Multiphoton excitation of these states is investigated using a Coulomb-Volkov approach. Extension to helium: two-photon double ionization study shows the influence of electronic correlations in both ground and final state. Huge quantity of information such as angular and energetic distributions as well as total cross sections is available. (author)

Neutron Irradiation Tests of Pressure Transducers in Liquid Helium

CERN Document Server

Amand, J F; Casas-Cubillos, J; Thermeau, J P

1999-01-01

The superconducting magnets of the future Large Hadron Collider (LHC) at CERN will operate in pressurised superfluid helium (1 bar, 1.9 K). About 500 pressure transducers will be placed in the liquid helium bath for monitoring the filling and the pressure transients after resistive transitions. Their precision must remain better than 100 mbar at pressures below 2 bar and better than 5% for higher pressures (up to 20 bar), with temperatures ranging from 1.8 K to 300 K. All the tested transducers are based on the same principle: the fluid or gas is separated from a sealed reference vacuum by an elastic membrane; its deformation indicates the pressure. The transducers will be exposed to high neutron fluence (2 kGy, 1014 n/cm2 per year) during the 20 years of machine operation. This irradiation may induce changes both on the membranes characteristics (leakage, modification of elasticity) and on gauges which measure their deformations. To investigate these effects and select the transducer to be used in the LHC, a...

The independence of irradiation creep in austenitic alloys of displacement rate and helium to dpa ratio

Energy Technology Data Exchange (ETDEWEB)

Garner, F.A.; Toloczko, M.B. [Pacific Northwest National Lab., Richland, WA (United States); Grossbeck, M.L. [Oak Ridge National Lab., TN (United States)

1997-04-01

The majority of high fluence data on the void swelling and irradiation creep of austenitic steels were generated at relatively high displacement rates and relatively low helium/dpa levels that are not characteristic of the conditions anticipated in ITER and other anticipated fusion environments. After reanalyzing the available data, this paper shows that irradiation creep is not directly sensitive to either the helium/dpa ratio or the displacement rate, other than through their possible influence on void swelling, since one component of the irradiation creep rate varies with no correlation to the instantaneous swelling rate. Until recently, however, the non-swelling-related creep component was also thought to exhibit its own strong dependence on displacement rate, increasing at lower fluxes. This perception originally arose from the work of Lewthwaite and Mosedale at temperatures in the 270-350{degrees}C range. More recently this perception was thought to extend to higher irradiation temperatures. It now appears, however, that this interpretation is incorrect, and in fact the steady-state value of the non-swelling component of irradiation creep is actually insensitive to displacement rate. The perceived flux dependence appears to arise from a failure to properly interpret the impact of the transient regime of irradiation creep.

Light ion irradiation for unfavorable soft tissue sarcoma

International Nuclear Information System (INIS)

Linstadt, D.; Castro, J.R.; Phillips, T.L.; Petti, P.L.; Collier, J.M.; Daftari, I.; Schoethaler, R.; Rayner, A.

1990-09-01

Between 1978 and 1989, 32 patients with unfavorable soft tissue sarcoma underwent light ion (helium, neon) irradiation with curative intent at Lawrence Berkeley Laboratory. The tumors were located in the trunk in 22 patients and head and neck in 10. Macroscopic tumor was present in 22 at the time of irradiation. Two patients had tumors apparently induced by previous therapeutic irradiation. Follow-up times for surviving patients ranged from 4 to 121 months (median 27 months). The overall 3-year actuarial local control rate was 62%; the corresponding survival rate was 50%. The 3-year actuarial control rate for patients irradiated with macroscopic tumors was 48%, while none of the patients with microscopic disease developed local recurrence (100%). The corresponding 3-year actuarial survival rates were 40% (macroscopic) and 78% (microscopic). Patients with retroperitoneal sarcoma did notably well; the local control rate and survival rate were 64% and 62%, respectively. Complications were acceptable; there were no radiation related deaths, while two patients (6%) required operations to correct significant radiation-related injuries. These results appear promising compared to those achieved by low -LET irradiation, and suggest that this technique merits further investigation

Kinetic processes in a laser-heated helium--nitrogen plasma for use as a uv laser medium

International Nuclear Information System (INIS)

Brown, R.T.

1975-01-01

Experimental and theoretical studies of an optically pumped electric discharge laser in helium-nitrogen mixtures are described. While the inherent efficiency of this system is rather low, these studies illustrate the basic parameters controlling the dynamics and efficiency of such a laser. In the experiments, intense diffuse discharges were obtained at pressures up to 12 atm and amplified spontaneous emission along the axis of the discharge was observed. The numerical modeling studies showed qualitative agreement with the experimental data and gave an optimized value of the kinetic coupling efficiency (absorbed 10.6-μ power to uv laser power) of 1.6% and of the total efficiency (energy stored in the TEA laser supply to uv output energy) of 0.1 to 0.2%

Time-resolved Thomson scattering on high-intensity laser-produced hot dense helium plasmas

International Nuclear Information System (INIS)

Sperling, P; Liseykina, T; Bauer, D; Redmer, R

2013-01-01

The introduction of brilliant free-electron lasers enables new pump–probe experiments to characterize warm and hot dense matter states, i.e. systems at solid-like densities and temperatures of one to several hundred eV. Such extreme conditions are relevant for high-energy density studies such as, e.g., in planetary physics and inertial confinement fusion. We consider here a liquid helium jet pumped with a high-intensity optical short-pulse laser that is subsequently probed with brilliant soft x-ray radiation. The optical short-pulse laser generates a strongly inhomogeneous helium plasma which is characterized with particle-in-cell simulations. We derive the respective Thomson scattering spectrum based on the Born–Mermin approximation for the dynamic structure factor considering the full density and temperature-dependent Thomson scattering cross section throughout the target. We observe plasmon modes that are generated in the interior of the target and study their temporal evolution. Such pump–probe experiments are promising tools to measure the important plasma parameters density and temperature. The method described here can be applied to various pump–probe scenarios by combining optical lasers, soft x-rays and hard x-ray sources. (paper)

Calculation of displacement and helium production at the Clinton P. Anderson Los Alamos Meson Physics Facility (LAMPF) irradiation facility

International Nuclear Information System (INIS)

Wechsler, M.S.; Davidson, D.R.; Greenwood, L.R.; Sommer, W.F.

1984-01-01

CT: Differential and total displacement and helium production rates are calculated for copper irradiated by spallation neutrons and 760 MeV protons at the Clinton P. Anderson Los Alamos Meson Physics Facility (LAMPF). The calculations are performed using the SPECTER and VNMTC computer codes, the latter being specially designed for spallation radiation damage calculations. For comparison, similar SPECTER calculations are also described for irradiation of copper in EBR-II and RTNS-II. The results indicate substantial contributions to the displacement and helium production rates due to neutrons in the high-energy tail (above 20 MeV) of the LAMPF spallation neutron spectrum. Still higher production rates are calculated for irradiations in the direct proton beam. These results will provide useful background information for research to be conducted at a new irradiation facility at LAMPF

Frontiers in propulsion research: Laser, matter-antimatter, excited helium, energy exchange thermonuclear fusion

Science.gov (United States)

Papailiou, D. D. (Editor)

1975-01-01

Concepts are described that presently appear to have the potential for propulsion applications in the post-1990 era of space technology. The studies are still in progress, and only the current status of investigation is presented. The topics for possible propulsion application are lasers, nuclear fusion, matter-antimatter annihilation, electronically excited helium, energy exchange through the interaction of various fields, laser propagation, and thermonuclear fusion technology.

Structural and chemical evolution in neutron irradiated and helium-injected ferritic ODS PM2000 alloy

Energy Technology Data Exchange (ETDEWEB)

Jung, Hee Joon [Energy and Environment Directorate, Pacific Northwest National Laboratory, Richland, WA 99354 (United States); Edwards, Dan J., E-mail: dan.edwards@pnnl.gov [Energy and Environment Directorate, Pacific Northwest National Laboratory, Richland, WA 99354 (United States); Kurtz, Richard J. [Energy and Environment Directorate, Pacific Northwest National Laboratory, Richland, WA 99354 (United States); Yamamoto, Takuya; Wu, Yuan [Department of Mechanical Engineering, University of California, Santa Barbara, CA 93106 (United States); Odette, G. Robert [Department of Mechanical Engineering, University of California, Santa Barbara, CA 93106 (United States); Materials Department, University of California, Santa Barbara, CA 93106 (United States)

2017-02-15

An investigation of the influence of helium on damage evolution under neutron irradiation of an 11 at% Al, 19 at% Cr ODS ferritic PM2000 alloy was carried out in the High Flux Isotope Reactor (HFIR) using a novel in situ helium injection (ISHI) technique. Helium was injected into adjacent TEM discs from thermal neutron {sup 58}Ni(n{sub th},γ) {sup 59}Ni(n{sub th},α) reactions in a thin NiAl layer. The PM2000 undergoes concurrent displacement damage from the high-energy neutrons. The ISHI technique allows direct comparisons of regions with and without high concentrations of helium since only the side coated with the NiAl experiences helium injection. The corresponding microstructural and microchemical evolutions were characterized using both conventional and scanning transmission electron microscopy techniques. The evolutions observed include formation of dislocation loops and associated helium bubbles, precipitation of a variety of phases, amorphization of the Al{sub 2}YO{sub 3} oxides (which also variously contained internal voids), and several manifestations of solute segregation. Notably, high concentrations of helium had a significant effect on many of these diverse phenomena. These results on PM2000 are compared and contrasted to the evolution of so-called nanostructured ferritic alloys (NFA).

Helium behaviour in nuclear glasses

International Nuclear Information System (INIS)

Fares, T.

2011-01-01

The present thesis focuses on the study of helium behavior in R7T7 nuclear waste glass. Helium is generated by the minor actinides alpha decays incorporated in the glass matrix. Therefore, four types of materials were used in this work. These are non radioactive R7T7 glasses saturated with helium under pressure, glasses implanted with 3 He + ions, glasses doped with curium and glasses irradiated in nuclear reactor. The study of helium solubility in saturated R7T7 glass has shown that helium atoms are inserted in the glass free volume. The results yielded a solubility of about 10 16 at. cm -3 atm. -1 . The incorporation limit of helium in this type of glass has been determined; its value amounted to about 2*10 21 at. cm -3 , corresponding to 2.5 at.%. Diffusion studies have shown that the helium migration is controlled by the single population dissolved in the glass free volume. An ideal diffusion model was used to simulate the helium release data which allowed to determine diffusion coefficients obeying to the following Arrhenius law: D = D 0 exp(-E a /kBT), where D 0 = 2.2*10 -2 and 5.4*10 -3 cm 2 s -1 and E a = 0.61 eV for the helium saturated and the curium doped glass respectively. These results reflect a thermally activated diffusion mechanism which seems to be not influenced by the glass radiation damage and helium concentrations studied in the present work (up to 8*10 19 at. g -1 , corresponding to 0.1 at.%). Characterizations of the macroscopic, structural and microstructural properties of glasses irradiated in nuclear reactor did not reveal any impact associated with the presence of helium at high concentrations. The observed modifications i.e. a swelling of 0.7 %, a decrease in hardness by 38 %, an increase between 8 and 34 % of the fracture toughness and a stabilization of the glass structure under irradiation, were attributed to the glass nuclear damage induced by the irradiation in reactor. Characterizations by SEM and TEM of R7T7 glasses implanted

Remote helium leak test of the DUPIC fuel rod

International Nuclear Information System (INIS)

Kim, W. K; Kim, S. S.; Lim, S. P.; Lee, J. W.; Yang, M. S.

1998-01-01

DUPIC(Direct Use of spent PWR fuel In CANDU reactor) is one of dry reprocessing fuel cycles to reuse irradiated PWR fuel in CANDU power plant. DUPIC fuel is so radioactive that DUPIC fuel is remotely fabricated at hot cell such as IMEF hot cell in which radiation is shielded and remote operation is possible. In this study, Helium leakage has been tested for the simulated DUPIC fuel rod manufactured by Nd:YAG laser end-cap welding at simulated hot cell. The remote inspection technique has been developed to evaluate the soundness of DUPIC fuel fabricated through new processes. Vacuum chamber has been developed to be remotely operated by manipulators at hot cell. As the result of remote test, Helium leakage of DUPIC fuel rod is around background level, CANDU specification has been satisfied. In the result of the study, remote test has been successfully performed at the simulated hot cell, and the soundness of DUPIC fuel rod welded by Nd:YAG laser has been confirmed

The effect of low energy helium ion irradiation on tungsten-tantalum (W-Ta) alloys under fusion relevant conditions

Science.gov (United States)

Gonderman, S.; Tripathi, J. K.; Novakowski, T. J.; Sizyuk, T.; Hassanein, A.

2017-08-01

Currently, tungsten remains the best candidate for plasma-facing components (PFCs) for future fusion devices because of its high melting point, low erosion, and strong mechanical properties. However, continued investigation has shown tungsten to undergo severe morphology changes under fusion-like conditions. These results motivate the study of innovative PFC materials which are resistant to surface morphology evolution. The goal of this work is to examine tungsten-tantalum (W-Ta) alloys, a potential PFC material, and their response to low energy helium ion irradiation. Specifically, W-Ta samples are exposed to 100 eV helium irradiations with a flux of 1.15 × 1021 ions m-2 s-1, at 873 K, 1023 K, and 1173 K for 1 h duration. Scanning electron microscopy (SEM) reveals significant changes in surface deterioration due to helium ion irradiation as a function of both temperature and tantalum concentration in W-Ta samples. X-Ray Diffraction (XRD) studies show a slight lattice parameter expansion in W-Ta alloy samples compared to pure W samples. The observed lattice parameter expansion in W-Ta alloy samples (proportional to increasing Ta wt.% concentrations) reflect significant differences observed in the evolution of surface morphology, i.e., fuzz development processes for both increasing Ta wt.% concentration and target temperature. These results suggest a correlation between the observed morphology differences and the induced crystal structure change caused by the presence of tantalum. Shifts in the XRD peaks before and after 100 eV helium irradiation with a flux of 1.15 × 1021 ions m-2 s-1, 1023 K, for 1 h showed a significant difference in the magnitude of the shift. This has suggested a possible link between the atomic spacing of the material and the accumulated damage. Ongoing research is needed on W-Ta alloys and other innovative materials for their application as irradiation resistant materials in future fusion or irradiation environments.

Excitation and ionization of hydrogen and helium atoms by femtosecond laser pulses: theoretical approach by Coulomb-Volkov states; Excitation et ionisation des atomes d'hydrogene et d'helium par des impulsions laser femtosecondes: approche theorique par des etats de Coulomb-Volkov

Energy Technology Data Exchange (ETDEWEB)

Guichard, R

2007-12-15

We present a theoretical approach using Coulomb-Volkov states that appears useful for the study of atomic multi-photonic processes induced by intense XUV femtosecond laser pulses. It predicts hydrogen ionization spectra when it is irradiated by laser pulses in perturbations conditions. Three ways have been investigated. Extension to strong fields when {Dirac_h}{omega} > I{sub p}: it requires to include the hydrogen ground state population, introducing it in standard Coulomb-Volkov amplitude leads to saturated multi-photonic ionization. Extension to multi-photonic transitions with {Dirac_h}{omega} < I{sub p}: new quantum paths are open by the possibility to excite the lower hydrogen bound states. Multiphoton excitation of these states is investigated using a Coulomb-Volkov approach. Extension to helium: two-photon double ionization study shows the influence of electronic correlations in both ground and final state. Huge quantity of information such as angular and energetic distributions as well as total cross sections is available. (author)

Laser spectroscopy of exotic RI atoms in superfluid helium-OROCHI experiment

International Nuclear Information System (INIS)

Furukawa, T.; Matsuo, Y.; Hatakeyama, A.; Fujikake, K.; Matsuura, Y.; Kobayashi, T.; Shimoda, T.

2010-01-01

We have been developing a new laser spectroscopic technique 'OROCHI,' which is based on the combination of superfluid helium as a stopper of radioactive isotope (RI) beam and in-situ laser spectroscopy of RI atoms, for determining spins and moments of exotic RIs. By using this unique technique, it is feasible to measure nuclear spins and electromagnetic moments of extremely low yield RI (estimated as less than 1 pps). Recently, we have demonstrated that nuclear spins and moments are obtained from Zeeman and hyperfine splittings of stable Rb isotopes measured using this OROCHI technique. Details of this laser spectroscopy method in He II 'OROCHI' and the summary of our development are presented.

Sapphire capillary interstitial irradiators for laser medicine

Science.gov (United States)

Shikunova, I. A.; Dolganova, I. N.; Dubyanskaya, E. N.; Mukhina, E. E.; Zaytsev, K. I.; Kurlov, V. N.

2018-04-01

In this paper, we demonstrate instruments for laser radiation delivery based on sapphire capillary needles. Such sapphire irradiators (introducers) can be used for various medical applications, such as photodynamic therapy, laser hyperthermia, laser interstitial thermal therapy, and ablation of tumors of various organs. Unique properties of sapphire allow for effective redistribution of the heat, generated in biological tissues during their exposure to laser radiation. This leads to homogeneous distribution of the laser irradiation around the needle, and lower possibility of formation of the overheating focuses, as well as the following non-transparent thrombi.

LCLS in—photon out: fluorescence measurement of neon using soft x-rays

Science.gov (United States)

Obaid, Razib; Buth, Christian; Dakovski, Georgi L.; Beerwerth, Randolf; Holmes, Michael; Aldrich, Jeff; Lin, Ming-Fu; Minitti, Michael; Osipov, Timur; Schlotter, William; Cederbaum, Lorenz S.; Fritzsche, Stephan; Berrah, Nora

2018-02-01

We measured the fluorescence photon yield of neon upon soft x-ray ionization (∼1200 eV) from the x-ray free-electron laser at Linac Coherent Light Source, and demonstrated the usage of a grazing incidence spectrometer with a variable line spacing grating to perform x-ray fluorescence spectroscopy on a gas phase system. Our measurements also allowed us to estimate the focal size of the beam from the theoretical description developed, in terms of the rate equation approximation accounting for photoionization shake off of neutral neon and double auger decay of single core holes.

Neutron-irradiation + helium hardening and embrittlement modeling of 9% Cr-steels in an engineering perspective (HELENA)

International Nuclear Information System (INIS)

Chaouadi, Rachid

2008-01-01

This report provides a physically-based engineering model to estimate the radiation hardening of 9%Cr-steels under both displacement damage (dpa) and helium. The model is essentially based on the dispersed barrier hardening theory and the dynamic re-solution of helium under displacement cascades. However, a number of assumptions and simplifications were considered to obtain a simple description of irradiation hardening and embrittlement primarily relying on the available experimental data. As a result, two components were basically identified, the dpa component that can be associated with black dots and small loops and the He-component accounting for helium bubbles. The dpa component is strongly dependent on the irradiation temperature and its dependence law was based on a first-order annealing kinetics. The damage accumulation law was also modified to take saturation into account. Finally, the global kinetics of the damage accumulation kept defined, its amplitude is fitted to one experimental condition. The model was rationalized on an experimental database that mainly consists of ∝9%Cr-steels irradiated in the technologically important temperature range of 50 to 600 C up do 50 dpa and with a He-content up to ∝5000 appm, including neutron and proton irradiation as well as implantation. The test temperature effect is taken into account through a normalization procedure based on the change of the Young's modulus and the anelastic deformation that occurs at high temperature. Finally, the hardening-to-embrittlement correlation is obtained using the load diagram approach. Despite the large experimental scatter, inherent to the variety of the materials and irradiation as well as testing conditions, the obtained results are very promising. Improvement of the model performance is still possible by including He-hardening saturation and high temperature softening but unfortunately, at this stage, a number of conflicting experimental data reported in literature should

Neutron-irradiation + helium hardening and embrittlement modeling of 9% Cr-steels in an engineering perspective (HELENA)

Energy Technology Data Exchange (ETDEWEB)

Chaouadi, Rachid

2008-07-01

This report provides a physically-based engineering model to estimate the radiation hardening of 9%Cr-steels under both displacement damage (dpa) and helium. The model is essentially based on the dispersed barrier hardening theory and the dynamic re-solution of helium under displacement cascades. However, a number of assumptions and simplifications were considered to obtain a simple description of irradiation hardening and embrittlement primarily relying on the available experimental data. As a result, two components were basically identified, the dpa component that can be associated with black dots and small loops and the He-component accounting for helium bubbles. The dpa component is strongly dependent on the irradiation temperature and its dependence law was based on a first-order annealing kinetics. The damage accumulation law was also modified to take saturation into account. Finally, the global kinetics of the damage accumulation kept defined, its amplitude is fitted to one experimental condition. The model was rationalized on an experimental database that mainly consists of {proportional_to}9%Cr-steels irradiated in the technologically important temperature range of 50 to 600 C up do 50 dpa and with a He-content up to {proportional_to}5000 appm, including neutron and proton irradiation as well as implantation. The test temperature effect is taken into account through a normalization procedure based on the change of the Young's modulus and the anelastic deformation that occurs at high temperature. Finally, the hardening-to-embrittlement correlation is obtained using the load diagram approach. Despite the large experimental scatter, inherent to the variety of the materials and irradiation as well as testing conditions, the obtained results are very promising. Improvement of the model performance is still possible by including He-hardening saturation and high temperature softening but unfortunately, at this stage, a number of conflicting experimental data

A study of the effect of helium concentration and displacement damage on the microstructure of helium ion irradiated tungsten

Science.gov (United States)

Harrison, R. W.; Greaves, G.; Hinks, J. A.; Donnelly, S. E.

2017-11-01

Transmission electron microscopy (TEM) with in-situ He ion irradiation has been used to examine the damage microstructure of W when varying the helium concentration to displacement damage ratio, irradiation temperature and total dose. Irradiations employed 15, 60 or 85 keV He ions, at temperatures between 500 and 1000 °C up to doses of ∼3.0 DPA. Once nucleated and grown to an observable size in the TEM, bubble diameter as a function of irradiation dose did not measurably increase at irradiation temperatures of 500 °C between 1.0 and 3.0 DPA; this is attributed to the low mobility of vacancies and He/vacancy complexes at these temperatures. Bubble diameter increased slightly for irradiation temperatures of 750 °C and rapidly increased when irradiated at 1000 °C. Dislocation loops were observed at irradiation temperatures of 500 and 750 °C and no loops were observed at 1000 °C. Burgers vectors of the dislocations were determined to be b = ±½ type only and both vacancy and interstitial loops were observed. The proportion of interstitial loops increased with He-appm/DPA ratio and this is attributed to the concomitant increase in bubble areal density, which reduces the vacancy flux for both the growth of vacancy-type loops and the annihilation of interstitial clusters.

Effects of high heat flux hydrogen and helium mixture beam irradiation on surface modification and hydrogen retention in tungsten materials

International Nuclear Information System (INIS)

Tokunaga, K.; Fujiwara, T.; Ezato, K.; Suzuki, S.; Akiba, M.; Kurishita, H.; Nagata, S.; Tsuchiya, B.; Tonegawa, A.; Yoshida, N.

2009-01-01

High heat flux experiments using a hydrogen-helium mixture beam have been carried out on powder metallurgy tungsten (PM-W) and ultra fine grain W-TiC alloy (W-0.5 wt%TiC-H 2 ). The energy of is 18 keV. Beam flux and heat flux at the beam center is 2.0 x 10 21 atoms/m 2 s and 7.0 MW/m 2 , respectively. Typical ratio of He/D ion is 0.25. Beam duration is 1.5-3 s and interval of beam shot start is 30 s. The samples are irradiated up to a fluence of 10 22 -10 24 He/m 2 by the repeated irradiation pulses. After the irradiation, surface modification by the irradiation and hydrogen retention, surface composition have been investigated. Surface modification by hydrogen-helium mixture beams is completely different from results of single beam irradiation. In particular, mixture beam irradiation causes remarkably high hydrogen retention.

Retention of hydrogen isotopes and helium in nickel

Energy Technology Data Exchange (ETDEWEB)

Okada, Mitsumasa; Sato, Rikiya; Yamaguchi, Kenji; Yamawaki, Michio [Tokyo Univ., Tokai, Ibaraki (Japan). Nuclear Engineering Research Lab.

1996-10-01

In the present study, a thin foil of nickel was irradiated by H{sub 2}{sup +}, D{sub 2}{sup +} and He{sup +} to a fluence of 1.2-6.0x10{sup 20}/m{sup 2} using the TBTS (Tritium Beam Test System) apparatus. The thermal desorption spectroscopy (TDS) technique was employed to evaluate the total amount of retained hydrogen isotope and helium atoms in nickel. In the spectra, two peaks appeared at 440-585K and 720-735K for helium. Hydrogen isotopes irradiation after helium preirradiation were found to enhance the helium release and to decrease the peak temperatures. Helium irradiation after hydrogen isotopes preirradiation were found to enhance the helium release, but the peak temperature showed little difference from that without preirradiation. (author)

Photochemistry of the ozone-water complex in cryogenic neon, argon, and krypton matrixes.

Science.gov (United States)

Tsuge, Masashi; Tsuji, Kazuhide; Kawai, Akio; Shibuya, Kazuhiko

2013-12-12

The photochemistry of ozone-water complexes and the wavelength dependence of the reactions were studied by matrix isolation FTIR spectrometry in neon, argon, and krypton matrixes. Hydrogen peroxide was formed upon the irradiation of UV light below 355 nm. Quantitative analyses of the reactant and product were performed to evaluate the matrix cage effect of the photoreaction. In argon and krypton matrixes, a bimolecular O((1)D) + H2O → H2O2 reaction was found to occur to form hydrogen peroxide, where the O((1)D) atom generated by the photolysis of ozone diffused in the cryogenic solids to encounter water. In a neon matrix, hydrogen peroxide was generated through intracage photoreaction of the ozone-water complex, indicating that a neon matrix medium is most appropriate to study the photochemistry of the ozone-water complex.

Research on interaction of laser light and non-metals. Evaluation of laser irradiation behavior to concrete

International Nuclear Information System (INIS)

Yamada, Tomonori; Muramatsu, Toshiharu

2015-02-01

In this study the response of hardened cement pastes, which are a major component of concrete, to laser irradiation was investigated under various experimental conditions aiming at the future application to “laser-processing” of concrete. (1) 75 tests were performed with combinations of following experimental conditions: (a) a water/cement ratio of the hardened cement pastes was either of 0.25, 0.30, or 0.35; (b) a laser power density was either of 100, 200, 300, 400, or 500 W/cm 2 ; and (c) laser irradiation duration was ranging from 1 to 40 seconds. It was found that hardened cement paste subjected to laser irradiation explodes very easily to be hollowed in all the experimental conditions; this response is applicable to “laser-drilling” of a hardened cement paste. The “laser-drilling” speeds up following to laser power increment or to irradiation time extension. It was also found that samples tend to melt rather than explode under the irradiation with a smaller laser power density (100 W/cm 2 ) at a high water/cement ratio (0.35). (2) Totally 75 laser irradiation tests for fixed mortar blocks were performed with combinations of following experimental conditions: (a) fine aggregate in the mortar blocks was either of quartz, limestone, or Nachiguro-ishi; (b) a laser power density was either of 100, 200, 300, 400, or 500 W/cm 2 ; and (c) laser irradiation duration was ranging from 0.2 to 40 seconds. Although it was found that all kinds of the mortar fuse under laser irradiation after all, difference in the response to laser irradiation among the mortars was also found; energy density required to fuse the mortar including limestone was larger than that required to fuse the mortar including quartz or Nachiguro-ishi. (author)

Influence of helium generation rate and temperature history on mechanical properties of model Fe-Cr-Ni alloys irradiated in FFTF at relatively low displacement rates

International Nuclear Information System (INIS)

Hamilton, M.L.; Garner, F.A.; Edwards, D.J.

1993-01-01

In agreement with earlier studies conducted at higher displacement rates, evolution of mechanical properties of model Fe-Cr-Ni alloys irradiated at lower displacement rates in the 59 Ni isotopic doping experiment does not appear to be strongly affected by large differences in helium generation rate. This insensitivity to helium/dpa ratio is exhibited during both isothermal and non-isothermal irradiation. The overall behavior of the model alloys used in this study is dominated by the tendency to converge to a saturation strength level that is independent of thermomechanical starting state and helium/dpa ratio, but which is dependent on irradiation temperature and alloy composition

Experimental identification for physical mechanism of fiber-form nanostructure growth on metal surfaces with helium plasma irradiation

Energy Technology Data Exchange (ETDEWEB)

Takamura, S., E-mail: takamura@aitech.ac.jp [Faculty of Engineering, Aichi Institute of Technology, Yakusa-cho, Toyota 470-0392 (Japan); Uesugi, Y. [Faculty of Electrical and Computer Engineering, Institute of Science and Engineering, Kanazawa University, Kanazawa 920-1192 (Japan)

2015-11-30

Highlights: • Initial growth process of fiber-form nanostructure on metal surfaces under helium ion irradiation is given based on experimental knowledge, where the pitting of original surface and forming nano-walls and/or loop-like nanostructure works as precursors. • The physical mechanism of fiber growth is discussed in terms of shear modulus of metals influenced by helium content as well as surface temperature. • The physical model explains the reason why tantalum does not make sufficiently grown nano-fibers, and the temperature dependence of surface morphology of titanium. - Abstract: The initial stage of fiber-form nanostructure growth on metal surface with helium plasma irradiation is illustrated, taking recent research knowledge using a flux gradient technique, and including loop-like nano-scale structure as precursors. The growth mechanism of fibers is discussed in terms of the shear modulus of various materials that is influenced by the helium content as well as the surface temperature, and the mobility of helium atoms, clusters and/or nano-bubbles in the bulk, loops and fibers. This model may explain the reason why tantalum does not provide fiber-form nanostructure although the loop-like structure was identified. The model also suggests the mechanism of an existence of two kinds of nanostructure of titanium depending on surface temperature. Industrial applications of such nanostructures are suggested in the properties and the possibilities of its growth on other basic materials.

Realization of double-pulse laser irradiating scheme for laser ion sources

International Nuclear Information System (INIS)

Li Zhangmin; Jin Qianyu; Liu Wei; Zhang Junjie; Sha Shan; Zhao Huanyu; Sun Liangting; Zhang Xuezhen; Zhao Hongwei

2015-01-01

A double-pulse laser irradiating scheme has been designed and established for the production of highly charged ion beams at Institute of Modern Physics (IMP), Chinese Academy of Sciences. The laser beam output by a Nd : YAG laser is split and combined by a double of beam splitters, between which the split laser beams are transmitted along different optical paths to get certain time delay between each other. With the help of a quarter-wave plate before the first splitter, the energy ratio between the two laser pulses can be adjusted between 3 : 8 to 8 : 3. To testify its feasibility, a preliminary experiment was carried out with the new-developed double-pulse irradiating scheme to produce highly charged carbon ions. Comparing the results with those got from the previous single-pulse irradiating scheme, the differences in the time structure and Charge State Distribution (CSD) of the ion pulse were observed, but its mechanisms and optimization require further studies. (authors)

Control of the ORR-PSF pressure-vessel surveillance irradiation experiment temperature

International Nuclear Information System (INIS)

Miller, L.F.

1982-01-01

Control of the Oak Ridge Research Reactor Pool Side Facility (ORR-PSF) pressure vessel surveillance irradiation experiment temperature is implemented by digital computer control of electrical heaters under fixed cooling conditions. Cooling is accomplished with continuous flows of water in pipes between specimen sets and of helium-neon gas in the specimen set housings. Control laws are obtained from solutions of the discrete-time Riccati equation and are implemented with direct digital control of solid state relays in the electrical heater circuit. Power dissipated by the heaters is determined by variac settings and the percent of time that the solid state relays allow power to be supplied to the heaters. Control demands are updated every forty seconds

MD simulations of onset of tungsten fuzz formation under helium irradiation

International Nuclear Information System (INIS)

Lasa, A.; Henriksson, K.O.E.; Nordlund, K.

2013-01-01

When helium (He) escapes a fusion reactor plasma, a tungsten (W)-based divertor may, under some conditions, form a fuzz-like nano-morphology. This is a highly undesired phenomenon for the divertor, and is not well understood. We performed molecular dynamics simulations of high fluence He and also C-seeded He (He+C) irradiation on W, focusing on the effect of the high fluence, the temperature and the impurities on the onset of the structure formation. We concluded that MD reproduces the experimentally found square root of time dependence of the surface growth. The He atomic density decreases when increasing the number of He atoms in the cell. A higher temperature causes a larger bubble growth and desorption activity, specially for the pure He irradiation cases. It also it leads to W recrystallization for the He+C irradiation cases. Carbon acts as a local He trap for small clusters or single atoms and causes a larger loss of crystallinity of the W surface

Committee report on visual appearance of neon lights. Neon no hikari no miekata ni kansuru tokubetsu kenkyu iinkai hokoku

Energy Technology Data Exchange (ETDEWEB)

Kansaku, H. (Chukyo University, Nagoya (Japan). Faculty of Letters)

1991-04-25

Were summarized the results of experiments and literature searches, conducted by the Commettee on Visual Appearance of Neon Lights,'' which was set up to provide scientific and basic data for understanding of relationship between neon lights and psychological reaction of human, and for realizing of neon sign advertisements with playing a role as neon lights and without any environmental problems. Analytical results of influences of six colors, such as red, yellow, green, blue, violet, and white, brightnesses, and flickering frequencies to the psycological reaction of human on the direct observations of neon lights were described. Results of influences of the neon light incidence into the room to the psychology of residents were also introduced. Furthermore, evaluation of neon lights as an aspect was discussed. Consequently, based on the combination of activity and estimativity, some attentions to be payed on the setting-up of neon lights were pointed out. A red flickering neon light'' was given as clearly a bad example. 2 figs.

Effect of alpha self irradiation on helium migration in (U,Pu)O2 samples

International Nuclear Information System (INIS)

Pipon, Yves; Roudil, Daniele; Jegou, Christophe; Khodja, Hicham; Raepsaet, Caroline

2008-01-01

The helium behavior and its migration mechanisms in nuclear spent fuel (UOX and MOX) significantly impact the possible evolution of the spent fuel matrix in a closed system during interim storage or during a disposal repository. An experimental study has been conducted on (U,Pu)O 2 samples in order to investigate the impact of defects created by alpha decay on helium diffusion. One large part is devoted to thermal atomic diffusion and applied on 3 He implanted samples, annealed at 850 and 1000 deg. C. The He profiles, as implanted and after annealing, were investigated with the 3 He(d,p) 4 He nuclear reaction. Another part deals with the thermal release of 4 He amassed in the samples. The measured thermal diffusion coefficients are compared with previously published values, thereby highlighting the effect of the alpha self-irradiation on helium behavior. (authors)

Primordial atmosphere incorporation in planetary embryos and the origin of Neon in terrestrial planets

Science.gov (United States)

Jaupart, Etienne; Charnoz, Sebatien; Moreira, Manuel

2017-09-01

The presence of Neon in terrestrial planet mantles may be attributed to the implantation of solar wind in planetary precursors or to the dissolution of primordial solar gases captured from the accretionary disk into an early magma ocean. This is suggested by the Neon isotopic ratio similar to those of the Sun observed in the Earth mantle. Here, we evaluate the second hypothesis. We use general considerations of planetary accretion and atmospheric science. Using current models of terrestrial planet formation, we study the evolution of standard planetary embryos with masses in a range of 0.1-0.2 MEarth, where MEarth is the Earth's mass, in an annular region at distances between 0.5 and 1.5 Astronomical Units from the star. We determine the characteristics of atmospheres that can be captured by such embryos for a wide range of parameters and calculate the maximum amount of Neon that can be dissolved in the planet. Our calculations may be directly transposed to any other planet. However, we only know of the amount of Neon in the Earth's solid mantle. Thus we use Earth to discuss our results. We find that the amount of dissolved Neon is too small to account for the present-day Neon contents of the Earth's mantle, if the nebular gas disk completely disappears before the largest planetary embryos grow to be ∼0.2 MEarth. This leaves solar irradiation as the most likely source of Neon in terrestrial planets for the most standard case of planetary formation models.

Mechanical compression tests of beryllium pebbles after neutron irradiation up to 3000 appm helium production

Energy Technology Data Exchange (ETDEWEB)

Chakin, V., E-mail: vladimir.chakin@kit.edu [Karlsruhe Institute of Technology, Institite for Applied Materials, Hermann-von-Helmholtz-Platz 1, 76344 Eggenstein-Leopoldshafen (Germany); Rolli, R.; Moeslang, A. [Karlsruhe Institute of Technology, Institite for Applied Materials, Hermann-von-Helmholtz-Platz 1, 76344 Eggenstein-Leopoldshafen (Germany); Zmitko, M. [The European Joint Undertaking for ITER and the Development of Fusion Energy, c/Josep Pla, no. 2, Torres Diagonal Litoral, Edificio B3, 08019 Barcelona (Spain)

2015-04-15

Highlights: • Compression tests of highly neutron irradiated beryllium pebbles have been performed. • Irradiation hardening of beryllium pebbles decreases the steady-state strain-rates. • The steady-state strain-rates of irradiated beryllium pebbles exceed their swelling rates. - Abstract: Results: of mechanical compression tests of irradiated and non-irradiated beryllium pebbles with diameters of 1 and 2 mm are presented. The neutron irradiation was performed in the HFR in Petten, The Netherlands at 686–968 K up to 1890–2950 appm helium production. The irradiation at 686 and 753 K cause irradiation hardening due to the gas bubble formation in beryllium. The irradiation-induced hardening leads to decrease of steady-state strain-rates of irradiated beryllium pebbles compared to non-irradiated ones. In contrary, after irradiation at higher temperatures of 861 and 968 K, the steady-state strain-rates of the pebbles increase because annealing of irradiation defects and softening of the material take place. It was shown that the steady-state strain-rates of irradiated beryllium pebbles always exceed their swelling rates.

Abrupt changes in neon discharge plasma detected via the optogalvanic effect

Energy Technology Data Exchange (ETDEWEB)

Han, Xianming L., E-mail: xhan@butler.edu [Dept. of Physics and Astronomy, Butler University, Indianapolis, IN 46208 (United States); Blosser, Michael C. [Dept. of Physics and Astronomy, Butler University, Indianapolis, IN 46208 (United States); Misra, Prabhakar [Dept. of Physics and Astronomy, Howard University, Washington DC 20059 (United States); Chandran, Haridass [Dept. of Physical Science, Belfry School, Belfry, KY 41514 (United States)

2012-10-30

When a laser is tuned between two excited energy levels of a gas in a Direct Current discharge lamp, the discharge current will experience a temporary disturbance lasting tens or hundreds of microseconds known as the optogalvanic effect. We have carried out extensive studies of optogalvanic effects in neon discharge plasmas for transitions at 621.7 nm, 630.5 nm, 638.3 nm, 650.7 nm and 659.9 nm. A nonlinear least-squares Monte Carlo technique has been used to determine the relevant amplitude coefficients, decay rates and the instrumental time constant. We discovered an abrupt change in the neon discharge plasma at a discharge current of about 6 mA.

Assessment of repair welding technologies of irradiated materials

Energy Technology Data Exchange (ETDEWEB)

NONE

2013-08-15

Damages on reactor internals of stainless steels caused by stress corrosion cracking and fatigue were identified in aged BWR plants. Repair-welding is one of the practical countermeasure candidates to restore the soundness of components and structures. The project of 'Assessment of Repair welding Technologies of Irradiated Materials' has been carried out to develop the technical guideline regarding the repair-welding of reactor internals. In FY 2011, we investigated the fatigue strength of stainless steel SUS316L irradiated by YAG laser welding. Furthermore, revision of the technical guideline regarding the repair-welding of reactor internals was discussed. Diagram of tungsten inert gas (TIG) weld cracking caused by entrapped Helium was modified. Helium concentration for evaluation-free of TIG weld cracking caused by entrapped Helium was revised to 0.007appm from 0.01appm. (author)

Spectroscopic analysis of the density and temperature gradients in the laser-heated gas jet

International Nuclear Information System (INIS)

Matthews, D.L.; Lee, R.W.; Auerbach, J.M.

1981-01-01

We have performed an analysis of the x-ray spectra produced by a 1.0TW, lambda/sub L/-0.53μm laser-irradiated gas jet. Plasmas produced by ionization of neon, argon and N 2 + SF 6 gases were included in those measurements. Plasma electron density and temperature gradients were obtained by comparison of measured spectra with those produced by computer modeling. Density gradients were also obtained using laser interferometry. The limitations of this technique for plasma diagnosis will be discussed

Design of a single variable helium effects experiment for irradiation in FFTF [Fast Flux Test Facility] using alloys enriched in nickel 59

International Nuclear Information System (INIS)

Simons, R.L.; Brager, H.R.; Matsumoto, W.Y.

1986-03-01

Nickel enriched in nickel 59 was extracted from the fragments of a fracture toughness specimen of Inconel 600 irradiated in the Engineering Test Reactor (ETR). The nickel contained 2.0% nickel 59. Three heats of austenitic steel doped with nickel-59 were prepared and inserted in the Materials Open Test Assembly (MOTA) of the Fast Flux Test Facility (FFTF). The experiment was single variable in helium effects because chemically identical alloys without nickel-59 were being irradiated side by side with the doped material. The alloys doped with nickel 59 produced 10 to 100 times more helium than the control alloys. The materials included ternary and quaternary alloys in the form of transmission electron microscope (TEM) discs and miniature tensile specimens. The helium to dpa ratio was in the range 5 to 35 and was nearly constant throughout the irradiation. The exposures ranged from 0.25 to 50 displacements per atom (dpa) over the duration of the experiment. The irradiation temperatures covered the range of 360 to 600 0 C

Measurement of helium production cross sections of iron for d-T neutrons by helium accumulation method

Energy Technology Data Exchange (ETDEWEB)

Takao, Yoshiyuki; Kanda, Yukinori; Nagae, Koji; Fujimoto, Toshihiro [Kyushu Univ., Fukuoka (Japan); Ikeda, Yujiro

1997-03-01

Helium production cross sections of Iron were measured by helium accumulation method for neutron energies from 13.5 to 14.9 MeV. Iron samples were irradiated with FNS, an intense d-T neutron source of JAERI. As the neutron energy varies according to the emission angle at the neutron source, the samples were set around the neutron source and were irradiated by neutrons of different energy depending on each sample position. The amount of helium produced in a sample was measured by Helium Atoms Measurement System at Kyushu University. The results of this work are in good agreement with other experimental data in the literature and also compared with the evaluated values in JENDL-3. (author)

Tensile and fracture properties of EBR-II-irradiated V-15Cr-5Ti containing helium

International Nuclear Information System (INIS)

Grossbeck, M.L.; Horak, J.A.

1986-01-01

The alloy V-15Cr-5Ti was cyclotron-implanted with 80 appM He and subsequently irradiated in the Experimental Breeder Reactor (EBR-II) to 30 dpa. The same alloy was also irradiated in the 10, 20, and 30% cold-worked conditions. Irradiation temperatures ranged from 400 to 700 0 C. No significant effects of helium on mechanical properties were found in this temperature range although the neutron irradiation shifted the temperature of transition from cleavage to ductile fracture to about 625 0 C. Ten percent cold work was found to have a beneficial effect in reducing the tendency for cleavage fracture following irradiation, but high levels (20%) were observed to reduce ductility. Still higher levels (30%) improved ductility by inducing recovery during the elevated-temperature irradiation. Swelling was found to be negligible, but precipitates - titanium oxides or carbonitrides - contained substantial cavities

Laser shocks on helium, hydrogen and diamond: an experimental study of the warm dense matter zone; Chocs laser sur l'helium, l'hydrogene et le diamant: une etude experimentale de la 'Warm Dense Matter'

Energy Technology Data Exchange (ETDEWEB)

Brygoo, St

2006-11-15

The purpose of this work was to develop a new approach of laser shocks on pre-compressed targets in order to collect data concerning the equation of state in the warm dense matter zone of the phase diagram. The accuracy of the measurement has been increased by the use of a new metrology based on quartz. Quartz is considered as a standard for the measurement of both the pressure and the density, a model of an isentropic relaxation based on a Grueneisen type approximation has been developed. By combining laser shocks with diamond anvil cells and by using this new metrology, we have investigated the following systems: diamond, helium, hydrogen, deuterium and hydrogen-helium mixtures. The results for helium agree very well with the predictions of the Saumon-Chabrier model. The results for deuterium are consistent with the latest results found in literature. As for the results concerning hydrogen, they have showed the limits of the quartz-based metrology. In fact, by being so little dense we are at the limit of the application range of the quartz relaxation. A mixture of helium-hydrogen (50 %) has been investigated, no sign of phase separation has been found.

Performance of Shiva as a laser fusion irradiation facility

International Nuclear Information System (INIS)

Speck, D.R.; Bliss, E.S.; Glaze, J.A.; Johnson, B.C.; Manes, K.R.; Ozarski, R.G.; Rupert, P.R.; Simmons, W.W.; Swift, C.D.; Thompson, C.E.

1979-01-01

Shiva is a 20 beam Nd:Glass Laser and Target Irradiation Facility at the Lawrence Livermore Laboratory. The laser system and integrated target facility evolved during the last year from a large, untested, experimental laser system to a target irradiation facility which has provided significant laser driven inertial confinement fusion data. The operation of the facility is discussed

Effect of microstructure on helium bubble growth in irradiated nickel

International Nuclear Information System (INIS)

Sattler, M.L.

1986-01-01

Thin nickel films were irradiated with 80 keV helium ions at varying doses and varying temperatures in order to obtain a variety of final microstructures. The growth of bubbles was examined during in-situ irradiations at 950 0 C where migration and coalescence events were observed for bubbles as large as 60 nm. Further direct observations of bubble growth were made during annealing of the irradiated specimens. For sample with no visible bubbles before annealing, the heating to 0.51 T/sub M/ produced bubbles that increased in diameter with annealing time to the power n. For bubbles in the grain interior, n ∼ 1, and on the grain boundaries, n ∼ 0.6. Since no migration and coalescence or ripening theories predict this behavior, a theory described by transient diffusion to spherical sinks was developed to discuss the behavior. This theory predicts that n = 1 for bubbles growing in the grain interior and n = 0.5 for bubbles on the grain boundary. In other annealing of irradiated samples containing large bubble populations, the growth of large bubbles and shrinking of small bubbles was observed at a temperature equal to 0.54 T/sub M/. The theory of Ostwald ripening properly described this type of bubble growth. Mass spectrometer measurements of He content in the irradiated specimens showed a greater He retention in the Ni films that contained a significant bubble population than those with no visible bubbles

High burnup, high power irradiation behavior of helium-bonded mixed carbide fuel pins

International Nuclear Information System (INIS)

Levine, P.J.; Nayak, U.P.; Boltax, A.

1983-01-01

Large diameter (9.4 mm) helium-bonded mixed carbide fuel pins were successfully irradiated in EBR-II to high burnup (12%) at high power levels (100 kW/m) with peak cladding midwall temperatures of 550 0 C. The wire-wrapped pins were clad with 0.51-mm-thick, 20% cold-worked Type 316 stainless steel and contained hyperstoichiometric (Usub(0.8)Pusub(0.2))C fuel covering the smeared density range from 75-82% TD. Post-irradiation examinations revealed: extensive fuel-cladding mechanical interaction over the entire length of the fuel column, 35% fission gas release at 12% burnup, cladding carburization and fuel restructuring. (orig.)

The ArF laser for the next-generation multiple-patterning immersion lithography supporting green operations

Science.gov (United States)

Ishida, Keisuke; Ohta, Takeshi; Miyamoto, Hirotaka; Kumazaki, Takahito; Tsushima, Hiroaki; Kurosu, Akihiko; Matsunaga, Takashi; Mizoguchi, Hakaru

2016-03-01

Multiple patterning ArF immersion lithography has been expected as the promising technology to satisfy tighter leading edge device requirements. One of the most important features of the next generation lasers will be the ability to support green operations while further improving cost of ownership and performance. Especially, the dependence on rare gases, such as Neon and Helium, is becoming a critical issue for high volume manufacturing process. The new ArF excimer laser, GT64A has been developed to cope with the reduction of operational costs, the prevention against rare resource shortage and the improvement of device yield in multiple-patterning lithography. GT64A has advantages in efficiency and stability based on the field-proven injection-lock twin-chamber platform (GigaTwin platform). By the combination of GigaTwin platform and the advanced gas control algorithm, the consumption of rare gases such as Neon is reduced to a half. And newly designed Line Narrowing Module can realize completely Helium free operation. For the device yield improvement, spectral bandwidth stability is important to increase image contrast and contribute to the further reduction of CD variation. The new spectral bandwidth control algorithm and high response actuator has been developed to compensate the offset due to thermal change during the interval such as the period of wafer exchange operation. And REDeeM Cloud™, new monitoring system for managing light source performance and operations, is on-board and provides detailed light source information such as wavelength, energy, E95, etc.

Tritium and helium behavior in irradiated beryllium

International Nuclear Information System (INIS)

Billone, M.C.; Lin, C.C.; Baldwin, D.L.

1990-11-01

Large quantities of Be (> 100 metric tons) are planned for use in the ITER blanket design to enhance tritium breeding and to act as a thermal barrier between coolant and breeder. Tritium retention/release and He-induced swelling are important issues in blanket design. The data base on tritium and helium behavior in Be is reviewed. New data on tritium retention/release and He bubble growth are presented for Be irradiated to 5 x 10 22 n(E > 1 MeV)/cm 2 at ∼75 degree C and postirradiation-annealed for 700 hours at 500 degree C. A model (diffusion/desorption) is proposed and tested against the data base to determine tritium diffusivity and the desorption rate constant. Similarly a model for He-induced swelling is developed and tested against the data base. The dependence of tritium retention and release on He content and impurities (e.g. BeO) is also explored. 11 refs., 6 figs

FROM THE HISTORY OF LASER CREATION

Directory of Open Access Journals (Sweden)

I.M. Belousova

2014-03-01

Full Text Available The paper briefly describes the history of formation of a new science direction - quantum electronics, associated with the discovery of masers and lasers by scientists from the USA (Ch. Townes and the USSR (N.G. Basov and A. M. Prokhorov. The world's first ruby laser designed by T. Maiman is described. Some historical events devoted to creation and research of lasers are given in which the author of the paper as well as research workers from Vavilov State Optical Institute, ITMO University and LOMO have taken direct part in the development of solid-state and gas lasers (helium-neon, photodissociation, CO2-lasers and laser optical systems. Contribution of researchers from Vavilov State Optical Institute, LOMO and ITMO University to large-scale programs on development of lasers for laser nuclear fusion, laser weapons and “Phobos” program is shown. The paper deals in brief with new issues of development and application of lasers, mainly, within the project of laser orbital space station of the future, for the conversion of solar energy into laser radiation. Description of idea of solar energy transformation by fullerene-oxygen laser is presented. The patent for it has been taken out by Vavilov State Optical Institute. Developed fullerene-oxygen-iodine laser and laser structure models for industrial applications and solar energy conversion into laser radiation are described. Parameters for hypothetical laser-optical system of the future space station are given.

Beam experiments with state selected Ne (3P0, 3P2) metastable atoms

International Nuclear Information System (INIS)

Verheijen, M.J.

1984-01-01

Metastable rare gas atoms play an important role in all types of plasmas and gas discharges, e.g. in fluorescent lamps and in laser discharges (helium-neon laser or excimer lasers). In this thesis, the metastable states of NeI are studied. First, the theory of excited neon atoms and diatomic molecules is introduced, as well as Penning ionisation. Next, some experimental facilities are described (e.g. the dye laser system). With these instruments, natural lifetime measurements of the 2p fine structure states of NeI are carried out. Results are reported. Finally, total Penning ionisation cross sections are calculated using the optical potential model. (Auth.)

Tensile and fracture properties of EBR-II-irradiated V-15Cr-5Ti containing helium

Energy Technology Data Exchange (ETDEWEB)

Grossbeck, M.L.; Horak, J.A.

1986-01-01

The alloy V-15Cr-5Ti was cyclotron-implanted with 80 appM He and subsequently irradiated in the Experimental Breeder Reactor (EBR-II) to 30 dpa. The same alloy was also irradiated in the 10, 20, and 30% cold-worked conditions. Irradiation temperatures ranged from 400 to 700/sup 0/C. No significant effects of helium on mechanical properties were found in this temperature range although the neutron irradiation shifted the temperature of transition from cleavage to ductile fracture to about 625/sup 0/C. Ten percent cold work was found to have a beneficial effect in reducing the tendency for cleavage fracture following irradiation, but high levels (20%) were observed to reduce ductility. Still higher levels (30%) improved ductility by inducing recovery during the elevated-temperature irradiation. Swelling was found to be negligible, but precipitates - titanium oxides or carbonitrides - contained substantial cavities.

Two photon laser spectroscopy of antiprotonic helium atoms at CERN’s AD

CERN Document Server

Hori, M

2014-01-01

The ASACUSA collaboration of CERN has carried out two-photon laser spectroscopy of antiprotonic helium atoms using counter-propagating ultraviolet laser beams. This excited some non-linear transitions of the antiproton at the wavelengths λ = 139.8–197.0 nm, in a way that reduced the thermal Doppler broadening of the observed resonances. The resulting narrow spectral lines allowed the measurement of three transition frequencies with fractional precisions of 2.3–5 parts in 109. By comparing these values with three-body QED calculations, the antiproton-to-electron mass ratio was derived as 1836.1526736(23). We briefly review these results.

Measurements of three dimensional residual stress distribution on laser irradiated spot

International Nuclear Information System (INIS)

Tanaka, Hirotomo; Akita, Koichi; Ohya, Shin-ichi; Sano, Yuji; Naito, Hideki

2004-01-01

Three dimensional residual stress distributions on laser irradiated spots were measured using synchrotron radiation to study the basic mechanism of laser peening. A water-immersed sample of high tensile strength steel was irradiated with Q-switched and frequency-doubled Nd:YAG laser. The residual stress depth profile of the sample was obtained by alternately repeating the measurement and surface layer removal by electrolytic polishing. Tensile residual stresses were observed on the surface of all irradiated spots, whereas residual stress changed to compressive just beneath the surface. The depth of compressive residual stress imparted by laser irradiation and plastic deformation zone increased with increasing the number of laser pulses irradiated on the same spot. (author)

Laser source for dimensional metrology: investigation of an iodine stabilized system based on narrow linewidth 633 nm DBR diode

Science.gov (United States)

Rerucha, Simon; Yacoot, Andrew; Pham, Tuan M.; Cizek, Martin; Hucl, Vaclav; Lazar, Josef; Cip, Ondrej

2017-04-01

We demonstrated that an iodine stabilized distributed Bragg reflector (DBR) diode based laser system lasing at a wavelength in close proximity to λ =633 nm could be used as an alternative laser source to the helium-neon lasers in both scientific and industrial metrology. This yields additional advantages besides the optical frequency stability and coherence: inherent traceability, wider optical frequency tuning range, higher output power and high frequency modulation capability. We experimentally investigated the characteristics of the laser source in two major steps: first using a wavelength meter referenced to a frequency comb controlled with a hydrogen maser and then on an interferometric optical bench testbed where we compared the performance of the laser system with that of a traditional frequency stabilized He-Ne laser. The results indicate that DBR diode laser system provides a good laser source for applications in dimensional (nano)metrology, especially in conjunction with novel interferometric detection methods exploiting high frequency modulation or multiaxis measurement systems.

Measurement of OH density and air-helium mixture ratio in an atmospheric-pressure helium plasma jet

International Nuclear Information System (INIS)

Yonemori, Seiya; Ono, Ryo; Nakagawa, Yusuke; Oda, Tetsuji

2012-01-01

The absolute density of OH radicals in an atmospheric-pressure helium plasma jet is measured using laser-induced fluorescence (LIF). The plasma jet is generated in room air by applying a pulsed high voltage onto a quartz tube with helium gas flow. The time-averaged OH density is 0.10 ppm near the quartz tube nozzle, decreasing away from the nozzle. OH radicals are produced from water vapour in the helium flow, which is humidified by water adsorbed on the inner surface of the helium line and the quartz tube. When helium is artificially humidified using a water bubbler, the OH density increases with humidity and reaches 2.5 ppm when the water vapour content is 200 ppm. Two-dimensional distribution of air-helium mixture ratio in the plasma jet is also measured using the decay rate of the LIF signal waveform which is determined by the quenching rate of laser-excited OH radicals. (paper)

Comment on theories for helium-assisted void nucleation

International Nuclear Information System (INIS)

Russell, K.C.

1976-01-01

Voids form by agglomeration of irradiation-induced vacancies which remain after preferential absorption of self interstitials at dislocation lines. Helium which is formed by (n,α) transmutations and, in simulation studies, may be ion-implanted, often plays an important, but puzzling role. In some materials, very few voids form in the absence of helium, even after intense irradiation. In many other materials , voids form readily under a variety of irradiation conditions, even in the absence of helium. Why some materials require helium - typically in the 10 -6 apa (atom per atom) range - and others do not, and the reason for that particular level are by no means clear. The physics of void nucleation, particularly the role of helium, have been the subject of several theoretical papers. This note presents a critique of these theories, and then briefly outlines a new analysis which is not subject to their limitations. (Auth.)

Observation of the initial stage of the laser ablation

International Nuclear Information System (INIS)

Miyashita, Atsumi; Yoda, Osamu; Ohyanagi, Takasumi; Murakami, Kouichi.

1994-01-01

The time and space resolved properties of laser ablated carbon particles were measured by X-ray absorption spectroscopy using Laser Plasma X-ray (LPX) as an X-ray source. The energy density of the irradiation laser on the sample was in the range of 0.5-20 J/cm 2 and the time delay was varied between 0 and 120ns. The absorption spectra exhibits several peaks originated from level to level transitions and an intense broad absorption in the energy range of C-K edge. At a delay time of 120ns, the absorption peak of 1s → 2p transition of neutral carbon atom (C 0 ), C - , C + and C 2+ ions were observed. The absorption peak from C 0 is stronger as the probing position is closer to the sample surface and its intensity decreases rapidly with distance from the sample surface. The absorption peak C 2+ ion was observed only at comparatively distant positions from surface. The maximum speed of highly charged ions are faster than that of neutral atoms and negative charged ions. The neutral atom and lower charged ions are emitted from the sample surface even after laser irradiation. The spatial distribution of the laser ablated particles in the localized helium gas environment were measured. In the helium gas environment, the ablation plume is depressed by the helium cloud generated on the top of ablation plume. (author)

A laser scanner for imaging fluorophore labeled molecules in electrophoretic gels

Energy Technology Data Exchange (ETDEWEB)

Fisk, D.J.; Sutherland, J.C. [Brookhaven National Lab., Upton, NY (United States). Biology Dept.

1995-08-01

A laser scanner for imaging electrophoretic gels was constructed and tested. The scanner incorporates a green helium-neon (HeNe) laser (543.5nm wavelength) and can achieve a spatial resolution of 19{micro}m. The instrument can function in two modes : snap-shot and finish-line. In snapshot mode, all samples are electrophoresed for the same time and the gel is scanned after completion of electrophoresis, while in finish-line mode, fluorophore labeled samples are electrophoresed for a constant distance and the image is formed as the samples pass under the detector. The resolving power of the finish-line mode of imaging is found to be greater than that of the snapshot mode of imaging. This laser scanner is also compared with a Charge Coupled Device (CCD) camera and in terms of resolving power is found to be superior. Sensitivity of the instrument is presented in terms of the minimum amount of DNA that can be detected verses its molecular length.

NEON Citizen Science: Planning and Prototyping

Science.gov (United States)

Newman, S. J.; Henderson, S.; Gardiner, L. S.; Ward, D.; Gram, W.

2011-12-01

The National Ecological Observatory Network (NEON) will be a national resource for ecological research and education. NEON citizen science projects are being designed to increase awareness and educate citizen scientists about the impacts of climate change, land-use change, and invasive species on continental-scale ecological processes as well as expand NEON data collection capacity by enabling laypersons to collect geographically distributed data. The citizen science area of the NEON web portal will enable citizen scientists to collect, contribute, interpret, and visualize scientific data, as well as access training modules, collection protocols and targeted learning experiences related to citizen science project topics. For NEON, citizen science projects are a means for interested people to interact with and contribute to NEON science. Investigations at vast spatial and temporal scales often require rapid acquisition of large amounts of data from a geographically distributed population of "human sensors." As a continental-scale ecological observatory, NEON is uniquely positioned to develop strategies to effectively integrate data collected by non-scientists into scientific databases. Ultimately, we plan to work collaboratively to transform the practice of science to include "citizens" or non-scientists in the process. Doing science is not limited to scientists, and breaking down the barriers between scientists and citizens will help people better understand the power of using science in their own decision making. In preparation for fully developing the NEON citizen science program, we are partnering with Project BudBurst (PBB), a citizen science project focused on monitoring plant phenology. The educational goals of PBB are to: (1) increase awareness of climate change, (2) educate citizen scientists about the impacts of climate change on plants and the environment, and (3) increase science literacy by engaging participants in the scientific process. Phenology was

Irradiation hardening of Fe–9Cr-based alloys and ODS Eurofer: Effect of helium implantation and iron-ion irradiation at 300 °C including sequence effects

Energy Technology Data Exchange (ETDEWEB)

Heintze, C. [Helmholtz-Zentrum Dresden-Rossendorf, Bautzner Landstraße 400, 01328 Dresden (Germany); Bergner, F., E-mail: f.bergner@hzdr.de [Helmholtz-Zentrum Dresden-Rossendorf, Bautzner Landstraße 400, 01328 Dresden (Germany); Hernández-Mayoral, M. [CIEMAT, Avenida Complutense 22, 28040 Madrid (Spain); Kögler, R.; Müller, G.; Ulbricht, A. [Helmholtz-Zentrum Dresden-Rossendorf, Bautzner Landstraße 400, 01328 Dresden (Germany)

2016-03-15

Single-beam, dual-beam and sequential iron- and/or helium-ion irradiations are widely accepted to emulate more application-relevant but hardly accessible irradiation conditions of generation-IV fission and fusion candidate materials for certain purposes such as material pre-selection, identification of basic mechanisms or model calibration. However, systematic investigations of sequence effects capable to critically question individual approaches are largely missing. In the present study, sequence effects of iron-ion irradiations at 300 °C up to 5 dpa and helium implantations up to 100 appm He are investigated by means of post-irradiation nanoindentation of an Fe9%Cr model alloy, ferritic/martensitic 9%Cr steels T91 and Eurofer97 and oxide dispersion strengthened (ODS) Eurofer. Different types of sequence effects, both synergistic and antagonistic, are identified and tentative interpretations are suggested. It is found that different accelerated irradiation approaches have a great impact on the mechanical hardening. This stresses the importance of experimental design in attempts to emulate in-reactor conditions. - Highlights: • The single-beam He-ion implantations do not give rise to significant hardening. • The single-beam Fe-ion irradiations give rise to significant hardening, ΔH{sub Fe}. • Hardening due to sequential He-/Fe-ion irradiation is smaller than ΔH{sub Fe}. • Hardening due to simultaneous He-/Fe-ion irradiation is larger than ΔH{sub Fe}. • The He–Fe synergism for ODS-Eurofer is less pronounced than for Eurofer97.

Histological observation on dental hard tissue irradiated by ultrashort-pulsed laser

Science.gov (United States)

Uchizono, Takeyuki; Awazu, Kunio; Igarashi, Akihiro; Kato, Junji; Hirai, Yoshito

2006-04-01

In the field of dentistry, effectiveness of USPL irradiation is researched because USPL has less thermal side effect to dental hard tissue. In this paper, we observed morphological change and optical change of dental hard tissue irradiated by USPL for discussing the safety and effectiveness of USPL irradiation to dental hard tissues. Irradiated samples were crown enamel and root dentin of bovine teeth. Lasers were Ti:sapphire laser, which had pulse duration (P d)of 130 fsec and pulse repetition rate (f) of 1kHz and wavelength (l) of 800nm, free electron laser (FEL), which had P d of 15 μsec and f of 10Hz and wavelength of 9.6μm, and Er:YAG laser, which had P d of 250 μsec and f of 10Hz and wavelength of 2.94μm. After laser irradiation, the sample surfaces and cross sections were examined with SEM and EDX. The optical change of samples was observed using FTIR. In SEM, the samples irradiated by USPL had sharp and accurate ablation with no crack and no carbonization. But, in FEL and Er:YAG laser, the samples has rough ablation with crack and carbonization. It was cleared that the P/Ca ratio of samples irradiated by USPL had same value as non-irradiated samples. There was no change in the IR absorption spectrum between samples irradiated by USPL and non-irradiated sample. But, they of samples irradiated by FEL and Er:YAG laser, however, had difference value as non-irradiated samples. These results showed that USPL might be effective to ablate dental hard tissue without thermal damage.

Collisional interaction between metastable neon atoms

International Nuclear Information System (INIS)

Drunen, Wouter Johannes van

2008-01-01

In this thesis, the study of cold gases of neon atoms in different metastable states is described. It contains measurements of the collisional parameters for both the 3s[3/2] 2 and the 3s'[1/2] 0 metastable state and the dependence of the inelastic loss on external fields. Furthermore, the investigation of frequency dependent laser-induced collisions, and the possibility to excite photoassociation resonances is presented. For the measurements described here, neon atoms have been confined in a magnetooptical trap, in a magnetostatic trap, or in an optical dipole trap, respectively. By laser cooling inside the magnetic trap, atomic samples with more than 95 percent occupation of the magnetic substate m J = +2 could be prepared. They have a typical temperature of 0.5 mK, central densities up to 10 11 cm -3 , and a central phase-space density of up to 2.2.10 -7 . After loading the optical dipole trap from the magnetic trap, 2.5.10 6 atoms with typical temperatures of 0.1 mK, and central densities up to 5.10 10 cm -3 were trapped. By evaporative cooling of the atoms in the magnetic trap we could increase the phase-space density by a factor of 200 to 5.10 -5 . Investigating the frequency dependence of laser-induced collisions did not reveal an experimental signature for the excitation of photoassociation resonances. For the 3 D 3 line a frequency dependence of laser enhanced Penning ionization was observed. Measurement of the two-body loss coefficient as function of the magnetic field showed a field dependence of the inelastic loss. These losses increase towards both small and large offset fields. The implementation of an optical dipole trap allowed us to trap the 3 P 0 metastable state. From the trap loss measurements we determined the two-body loss coefficient of the 3 P 0 metastable state for both bosonic isotopes 20 Ne and 22 Ne. For 20 Ne we obtained β=6 +5 -4 .10 -10 cm 3 /s and for 22 Ne β = 11 +7 -6 .10 -10 cm 3 /s. (orig.)

Single event upset threshold estimation based on local laser irradiation

International Nuclear Information System (INIS)

Chumakov, A.I.; Egorov, A.N.; Mavritsky, O.B.; Yanenko, A.V.

1999-01-01

An approach for estimation of ion-induced SEU threshold based on local laser irradiation is presented. Comparative experiment and software simulation research were performed at various pulse duration and spot size. Correlation of single event threshold LET to upset threshold laser energy under local irradiation was found. The computer analysis of local laser irradiation of IC structures was developed for SEU threshold LET estimation. The correlation of local laser threshold energy with SEU threshold LET was shown. Two estimation techniques were suggested. The first one is based on the determination of local laser threshold dose taking into account the relation of sensitive area to local irradiated area. The second technique uses the photocurrent peak value instead of this relation. The agreement between the predicted and experimental results demonstrates the applicability of this approach. (authors)

Small scale demand type neon liquefaction plant

International Nuclear Information System (INIS)

Dube, W.P.; Slifka, A.J.; Bitsy, R.M.; Sparks, L.L.; Johnson, K.B.

1990-01-01

Low-temperature measurement of the thermal conductivity of insulating materials is generally made using a boil-off calorimetry technique involving liquid hydrogen (LH2). Liquid neon (LNe) has nearly the same normal boiling point as LH2, but has a much larger heat of vaporization, allowing extended run times. The main drawback of using LNe has been its excessive cost; $170.00 versus $1.50/l for LH2 (1989 prices). A neon liquefaction plant has been designed and constructed to capture, purify, and refrigerate the neon boil-off from calorimetry experiments. Recycling the neon reduces operating costs to approximately $20/l. The system consists of a purification section, a heat exchanger, LNe and LH2 storage dewars, and a fully automated control system. After purification, neon is liquified in the heat exchanger by LH2 flowing countercurrently through stainless steel cooling coils. Hydrogen flow is automatically adjusted to keep the neon at its normal saturation temperature, 27 K. The liquid neon is then stored in a dewar placed directly below the heat exchanger

Nano-pulsed laser irradiation scanning system for phase-change materials

International Nuclear Information System (INIS)

Kim, Sookyung; Li Xuezhe; Lee, Sangbin; Kim, Kyung-Ho; Lee, Seung-Yop

2008-01-01

Recently, the demand of a laser irradiation tester is increasing for phase change random access memory (PRAM) as well as conventional optical storage media. In this study, a nano-pulsed laser irradiation system is developed to characterize the optical property and writing performance of phase-change materials, based on a commercially available digital versatile disk (DVD) optical pick-up. The precisely controlled focusing and scanning on the material's surface are implemented using the auto-focusing mechanism and a voice coil motor (VCM) of the commercial DVD pick-up. The laser irradiation system provides various writing and reading functions such as adjustable laser power, pulse duration, recording pattern (spot, line and area), and writing/reading repetition, phase transition, and in situ reflectivity measurement before/after irradiation. Measurements of power time effect (PTE) diagram and reflectivity map of Ge 2 Sb 2 Te 5 samples show that the proposed laser irradiation system provides the powerful scanning tool to quantify the optical characteristics of phase-change materials

The osmotic fragility of human erythrocytes is inhibited by laser irradiation

International Nuclear Information System (INIS)

Habodaszova, D.; Sikurova, L.; Waczulikova, I.

2004-01-01

In this study we investigated the influence of green laser irradiation (532 nm, 30 mW, 31,7 J/cm 2 ) on the membrane integrity of human erythrocytes and compared the results with the effect of infrared laser irradiation (810 nm, 50 mW, 31,3 J/cm 2 ). To evaluate the membrane integrity of erythrocytes, one clinical parameter, the osmotic fragility, was investigated. We observed a decrease in osmotic fragility of the erythrocytes after irradiation by the green laser light as well as by the infrared laser compared to non-irradiated controls (Authors)

In-situ observation of weld joint of austenitic stainless steel due to helium irradiation

International Nuclear Information System (INIS)

Hamada, S.; Hojou, K.; Hishinuma, A.

1992-01-01

Microstructural evolution during helium ions irradiation in a weld metal containing 10% delta-ferrite of a weld joint of Ti-modified austenitic stainless steel were in-situ observed through a transmission electron microcopy. Very fine helium bubbles were observed in high number density in both a delta ferrite phase and a matrix to a dose of 3 x 10 19 ions·m -2 . Entirely different behavior appeared in both phases with increasing dose. Bubbles in a delta-ferrite phase were readily converted into voids during slight increment of dose, and these rapidly grew with additional increasing of dose. On the other hand, finer bubbles in a matrix were very stable during irradiation and did not grow any more up to 2 x 10 20 ions·m -2 . Swelling became much larger in a delta-ferrite phase than in a fcc matrix phase, resultantly ; This means an inverse phenomenon for conventional results that swelling is smaller in a ferrite phase than in a fcc phase. Sigma phase radiation-enhanced precipitated at the grain boundary between a delta-ferrite phase and a matrix at a dose 9 x 10 19 ions·m -2 . This phase grew in two dimensions with increasing dose. The chemical composition of the sigma phase observed during irradiation showed Cr and Mo enrichment, and Fe and Ni depletion compared with those of a sigma phase thermally produced. (author)

Impact of helium implantation and ion-induced damage on reflectivity of molybdenum mirrors

Energy Technology Data Exchange (ETDEWEB)

Garcia-Carrasco, A., E-mail: alvarogc@kth.se [Department of Fusion Plasma Physics, Royal Institute of Technology (KTH), Teknikringen 31, 100 44 Stockholm (Sweden); Petersson, P.; Hallén, A. [Department of Fusion Plasma Physics, Royal Institute of Technology (KTH), Teknikringen 31, 100 44 Stockholm (Sweden); Grzonka, J. [Faculty of Materials Science and Engineering, Warsaw University of Technology, 02-507 Warsaw (Poland); Institute of Electronic Materials Technology, 133 Wolczynska Str., 01-919 Warsaw (Poland); Gilbert, M.R. [Culham Centre for Fusion Energy, Culham Science Centre, Abingdon, Oxon OX14 3DB (United Kingdom); Fortuna-Zalesna, E. [Faculty of Materials Science and Engineering, Warsaw University of Technology, 02-507 Warsaw (Poland); Rubel, M. [Department of Fusion Plasma Physics, Royal Institute of Technology (KTH), Teknikringen 31, 100 44 Stockholm (Sweden)

2016-09-01

Molybdenum mirrors were irradiated with Mo and He ions to simulate the effect of neutron irradiation on diagnostic first mirrors in next-generation fusion devices. Up to 30 dpa were produced under molybdenum irradiation leading to a slight decrease of reflectivity in the near infrared range. After 3 × 10{sup 17} cm{sup −2} of helium irradiation, reflectivity decreased by up to 20%. Combined irradiation by helium and molybdenum led to similar effects on reflectivity as irradiation with helium alone. Ion beam analysis showed that only 7% of the implanted helium was retained in the first 40 nm layer of the mirror. The structure of the near-surface layer after irradiation was studied with scanning transmission electron microscopy and the extent and size distribution of helium bubbles was documented. The consequences of ion-induced damage on the performance of diagnostic components are discussed.

Effect of semiconductor GaAs laser irradiation on pain perception in mice

Energy Technology Data Exchange (ETDEWEB)

Zarkovic, N.; Manev, H.; Pericic, D.; Skala, K.; Jurin, M.; Persin, A.; Kubovic, M.

1989-01-01

The influence of subacute exposure (11 exposures within 16 days) of mice to the low power (GaAs) semiconductive laser-stimulated irradiation on pain perception was investigated. The pain perception was determined by the latency of foot-licking or jumping from the surface of a 53 degrees C hot plate. Repeated hot-plate testing resulted in shortening of latencies in both sham- and laser-irradiated mice. Laser treatment (wavelength, 905 nm; frequency, 256 Hz; irradiation time, 50 sec; pulse duration, 100 nsec; distance, 3 cm; peak irradiance, 50 W/cm2 in irradiated area; and total exposure, 0.41 mJ/cm2) induced further shortening of latencies, suggesting its stimulatory influence on pain perception. Administration of morphine (20 mg/kg) prolonged the latency of response to the hot plate in both sham- and laser-irradiated mice. This prolongation tended to be lesser in laser-irradiated animals. Further investigations are required to elucidate the mechanism of the observed effect of laser.

Morphology variation, composition alteration and microstructure changes in ion-irradiated 1060 aluminum alloy

Science.gov (United States)

Wan, Hao; Si, Naichao; Wang, Quan; Zhao, Zhenjiang

2018-02-01

Morphology variation, composition alteration and microstructure changes in 1060 aluminum irradiated with 50 keV helium ions were characterized by field emission scanning electron microscopy (FESEM) equipped with x-ray elemental scanning, 3D measuring laser microscope and transmission electron microscope (TEM). The results show that, helium ions irradiation induced surface damage and Si-rich aggregates in the surfaces of irradiated samples. Increasing the dose of irradiation, more damages and Si-rich aggregates would be produced. Besides, defects such as dislocations, dislocation loops and dislocation walls were the primary defects in the ion implanted layer. The forming of surface damages were related with preferentially sputtering of Al component. While irradiation-enhanced diffusion and irradiation-induced segregation resulted in the aggregation of impurity atoms. And the aggregation ability of impurity atoms were discussed based on the atomic radius, displacement energy, lattice binding energy and surface binding energy.

Acute effects of pulsed-laser irradiation on the arterial wall

Science.gov (United States)

Nakamura, Fumitaka; Kvasnicka, Jan; Lu, Hanjiang; Geschwind, Herbert J.; Levame, Micheline; Bousbaa, Hassan; Lange, Francoise

1992-08-01

Pulsed laser coronary angioplasty with an excimer or a holmium-yttrium-aluminum-garnet (Ho:YAG) laser may become an alternative treatment for patients with coronary artery disease. However, little is known about its acute consequences on the normal arterial wall. This study was designed to examine the acute histologic consequences of these two pulsed lasers on the arterial wall of normal iliac arteries in rabbits. Irradiation with each laser was performed in 15 normal iliac sites on eight male New Zealand white rabbits. The excimer laser was operated at 308 nm, 25 Hz, 50 mJ/mm2/pulse, and 135 nsec/pulse and the Ho:YAG laser was operated at 2.1 micrometers , 3/5 Hz, 400 mJ/pulse, and 250 microsecond(s) ec/pulse. The excimer and Ho:YAG laser were coupled into a multifiber wire-guided catheter of 1.4 and 1.5 mm diameter, respectively. The sites irradiated with excimer or Ho:YAG laser had the same kinds of histologic features, consisting of exfoliation of the endothelium, disorganization of internal elastic lamina, localized necrosis of vascular smooth muscle cells, and fissures in the medial layer. However, the sites irradiated with excimer laser had lower grading scores than those irradiated with Ho:YAG laser (p vascular injury.

ESR investigation of L-α-alanine and sucrose radicals produced by heavy-ion irradiation

International Nuclear Information System (INIS)

Nakagawa, K.; Sato, Y.

2005-01-01

We investigated sucrose and L-α-alanine radicals produced by heavy (particle) ion irradiation with various LETs (linear energy transfer). The impact of the heavy ions on the samples produced stable free radicals, which were analyzed by ESR (electron spin resonance). Identical spectra were measured after one year. The obtained spectral patterns were the same as those for helium (He), carbon (C), and neon (Ne) ions irradiation. The absorbed dose dependences for the irradiated sucrose and alanine samples were examined. The ESR response has a linear relation with the absorbed dose. The ESR response at 60 Gy was slightly lower than a linear line for sucrose; however, the response showed good linearity for the alanine. In addition, the total spin concentration obtained by heavy-ion irradiation correlated logarithmically with the LET. Qualitative ESR analyse showed that the production of sucrose and alanine radicals depended on both different particle irradiation and the LET under the same dose. Thus, the present ESR results imply that sucrose together with L-α-alanine can be used to monitor LET as well as the number of ionizing particle for the production of stable free radicals. (author)

A stochastic differential equations approach for the description of helium bubble size distributions in irradiated metals

Science.gov (United States)

Seif, Dariush; Ghoniem, Nasr M.

2014-12-01

A rate theory model based on the theory of nonlinear stochastic differential equations (SDEs) is developed to estimate the time-dependent size distribution of helium bubbles in metals under irradiation. Using approaches derived from Itô's calculus, rate equations for the first five moments of the size distribution in helium-vacancy space are derived, accounting for the stochastic nature of the atomic processes involved. In the first iteration of the model, the distribution is represented as a bivariate Gaussian distribution. The spread of the distribution about the mean is obtained by white-noise terms in the second-order moments, driven by fluctuations in the general absorption and emission of point defects by bubbles, and fluctuations stemming from collision cascades. This statistical model for the reconstruction of the distribution by its moments is coupled to a previously developed reduced-set, mean-field, rate theory model. As an illustrative case study, the model is applied to a tungsten plasma facing component under irradiation. Our findings highlight the important role of stochastic atomic fluctuations on the evolution of helium-vacancy cluster size distributions. It is found that when the average bubble size is small (at low dpa levels), the relative spread of the distribution is large and average bubble pressures may be very large. As bubbles begin to grow in size, average bubble pressures decrease, and stochastic fluctuations have a lessened effect. The distribution becomes tighter as it evolves in time, corresponding to a more uniform bubble population. The model is formulated in a general way, capable of including point defect drift due to internal temperature and/or stress gradients. These arise during pulsed irradiation, and also during steady irradiation as a result of externally applied or internally generated non-homogeneous stress fields. Discussion is given into how the model can be extended to include full spatial resolution and how the

Inert medium (helium) irradiation testing of pressure tube samples

International Nuclear Information System (INIS)

Ancuta, M.; Radu, V.; Stefan, V.; Preda, M.

2001-01-01

Irradiation tests currently performed in C-5 capsule aim at obtaining data and information concerning behavior to irradiation of pressure tubes of CANDU type fuel channel, to evidence the factors limiting operation life span. A calculation code for analysis and prediction of pressure tube behavior should be based upon periodical inspection results, post irradiation examination of the removed from reactor pressure tubes as well as on the experimental results obtained with materials subjected to irradiation conditions identical with the operational ones. Mechanical behavior analysis should focus both complex thermal-mechanical type stresses and mechanical properties alteration under irradiation. The experimental results should be applied: - to evaluate the irradiation effects upon mechanical properties of Zr-2.5% Nb exposed to fluences up to 10 21 n·cm -2 ; - to gather data concerning the real stress / real deformation characteristic from which characteristic quantities can be deduced as, for instance, elasticity modulus, plasticity modulus, exponent of stress term in the Tsu-Berteles relation, to be used within the CANTUP simulation code describing pressure tube behavior, currently developed at INR Pitesti; - to develop prediction methods of pressure tube behavior and merging with in-service inspection procedure in order to forecast the life span and the proper timing for replacement before major failures occur. The samples irradiated in C-5 capsule were extracted from the ends of Zr-2.5% Nb pressure tubes resulting from Cernavoda NPP Unit 1. The samples for tensile tests were extracted on longitudinal and transversal directions of the pressure tube. The tests were carried out under following conditions: - test environment temperature, 260 - 280 deg.C; - testing medium, helium at 1 - 6 b pressure; - neutron flux (E n > 1 MeV), 1 - 2 · 10 13 ncm -2 s -1 ; - neutron fluence (E n > 1 MeV), 4 · 10 20 ncm -2 . The following characteristics were obtained from tensile

Influence of helium injection schedule and prior thermomechanical treatment on the microstructure of ion-irradiated type 316 stainless steel

International Nuclear Information System (INIS)

Kohyama, A.; Ayrault, G.; Loomis, B.A.

1982-01-01

The objective of this work is to determine the evolution of the microstructure in first wall materials during irradiation with special emphasis on the effects of helium production, displacement damage rates and temperature

Cell and tissue kinetics of the subependymal layer in mouse brain following heavy charged particle irradiation

Energy Technology Data Exchange (ETDEWEB)

Manley, N.B.; Fabrikant, J.I.; Alpen, E.L.

1988-12-01

The following studies investigate the cellular response and cell population kinetics of the subependymal layer in the mouse brain exposed to heavy charged particle irradiation. Partial brain irradiation with helium and neon ions was confined to one cortex of the brain. Both the irradiated and the unirradiated contralateral cortex showed similar disturbances of the cell and tissue kinetics in the subependymal layers. The irradiated hemisphere exhibited histological damage, whereas the unirradiated side appeared normal histologically. This study concerns the cell population and cell cycle kinetics of the subependymal layer in the mouse brain, and the effects of charged particle irradiations on this cell population. Quantitative high resolution autoradiography was used to study the kinetic parameters in this cell layer. This study should help in understanding the effects of these high-energy heavy ions on normal mammalian brain tissue. The response of the mammalian brain exposure to charged particle ionizing radiation may be extremely variable. It varies from minimal physiological changes to overt tissue necrosis depending on a number of factors such as: the administered dose, dose-rate, the volume of the irradiated tissue, and the biological end-point being examined.

Laser-induced breakdown spectroscopy with laser irradiation resonant with vibrational transitions

International Nuclear Information System (INIS)

Khachatrian, Ani; Dagdigian, Paul J.

2010-01-01

An investigation of laser-induced breakdown spectroscopy (LIBS) of polymers, both in bulk form and spin coated on Si wafers, with laser irradiation in the mid-infrared spectral region is presented. Of particular interest is whether the LIBS signals are enhanced when the laser wavelength is resonant with a fundamental vibrational transition of the polymer. Significant increases in the LIBS signals were observed for irradiation on hydride stretch fundamental transitions, and the magnitude of the enhancement showed a strong dependence on the mode excited. The role of the substrate was investigated by comparison of results for bulk and spin-coated samples. The polymers investigated were Nylon 12 and poly(vinyl alcohol-co-ethylene).

Thermal imaging of high power diode lasers subject to back-irradiance

Science.gov (United States)

Li, C.; Pipe, K. P.; Cao, C.; Thiagarajan, P.; Deri, R. J.; Leisher, P. O.

2018-03-01

CCD-based thermoreflectance imaging and finite element modeling are used to study the two-dimensional (2D) temperature profile of a junction-down broad-area diode laser facet subject to back-irradiance. By determining the temperature rise in the active region (ΔΤAR) at different diode laser optical powers, back-irradiance reflectance levels, and back-irradiance spot locations, we find that ΔΤAR increases by nearly a factor of three when the back-irradiance spot is centered in the absorbing substrate approximately 5 μm away from the active region, a distance roughly equal to half of the back-irradiance spot FWHM (9 μm). This corroborates prior work studying the relationship between the back-irradiance spot location and catastrophic optical damage, suggesting a strong thermal basis for reduced laser lifetime in the presence of back-irradiance for diode lasers fabricated on absorbing substrates.

Helium charged-particle radiotherapy of locally advanced carcinoma of the esophagus, stomach, and biliary tract

International Nuclear Information System (INIS)

Castro, J.R.; Chen, G.T.Y.; Pitluck, S.

1983-01-01

Sixty-five patients with squamous carcinoma of the esophagus (32 patients), carcinoma of the stomach (18 patients) and carcinoma of the biliary tract (15 patients) received from 6000 to 7000 equivalent rad (60-70 Gray equivalents) of helium radiotherapy at 2.0 GyE per fraction, four fractions per day, using multiportal, spread-out Bragg peak therapy. All patients had locally advanced disease without evidence of distant metastases. Partial compensation for tissue inhomogeneities was accomplished. Although palliation of symptoms and regression of tumor was commonly seen, local failure occurred in most patients (77%). The median survival was 8 months. It does not appear that an increase in tumor dose relative to normal tissues can be achieved that would be high enough to increase locoregional control rates over historical control rates with low-LET irradiation. Further studies will be carried out with heavier particles such as neon or silicon in hopes of achieving greater biological effect on these difficult-to-control tumors. 22 references, 6 figures, 1 table

Effect of heavy ion irradiation on sucrose radical production

International Nuclear Information System (INIS)

Nakagawa, Kouichi; Sato, Yukio

2004-01-01

We investigated sucrose radicals produced by heavy-ion irradiation with various LETs (linear energy transfer) and the possibility for a sucrose ESR (electron spin resonance) dosimeter. The obtained spectral pattern was the same as that for helium (He) ions, carbon (C) ions, neon (Ne) ions, argon (Ar) ions, and iron (Fe) ions. Identical spectra were measured after one year, but the initial intensities decreased by a few percent when the samples were kept in ESR tubes with the caps at ambient temperature. The total spin concentration obtained by heavy-ion irradiation had a linear relation with the absorbed dose, and correlated logarithmically with the LET. Qualitative ESR analyses showed that the production of sucrose radicals depended on both the particle identity and the LET at the same dose. The production of spin concentration by He ions was the most sensitive to LET. Empirical relations between the LET and the spin yield for various particles imply that the LET at a certain dose can be estimated by the spin concentration. (authors)

Toxicity of laser irradiated photoactive fluoride PrF3 nanoparticles toward bacteria

International Nuclear Information System (INIS)

Pudovkin, M S; Korableva, S L; Krasheninnicova, A O; Nizamutdinov, A S; Semashko, V V; Zelenihin, P V; Alakshin, E M; Nevzorova, T A

2014-01-01

The article is devoted to exploration of biological effects of crystalline PrF 3 nanoparticles toward Salmonella typhimurium TA 98 bacteria under the laser irradiation. Obtained results show bactericidal activity of PrF 3 nanoparticles and optimal parameters of laser irradiation (power of laser irradiation, wavelength, diameter of the laser spoil, and exposure time) have been found under which the effects of bactericidal activity become the most significant. Survival of bacterial cells under laser irradiation with wavelength 532 nm in colloidal solution of PrF 3 nanoparticles was 39%, 34%, 20% for exposure times 5 minutes, 15 minutes and 30 minutes, correspondingly

Towards a laser fluence dependent nanostructuring of thin Au films on Si by nanosecond laser irradiation

International Nuclear Information System (INIS)

Ruffino, F.; Pugliara, A.; Carria, E.; Romano, L.; Bongiorno, C.; Fisicaro, G.; La Magna, A.; Spinella, C.; Grimaldi, M.G.

2012-01-01

Highlights: ► Au nanoclusters are produced by nanosecond laser irradiations of thin Au film on Si. ► The shape, size, and surface density of the Au nanoclusters are tunable by laser fluence. ► The formation dynamic of the Au nanoclusters under nanosecond laser irradiation is analyzed. - Abstract: In this work, we study the nanostructuring effects of nanosecond laser irradiations on 5 nm thick Au film sputter-deposited on Si. After deposition of Au on Si substrate, nanosecond laser irradiations were performed increasing the laser fluence from 750 to 1500 mJ/cm 2 . Several analyses techniques, such as Rutherford backscattering spectrometry, scanning electron microscopy, atomic force microscopy, and transmission electron microscopy were crossed to study the morphological evolution of the Au film as a function of laser fluence. In particular, the formation of Au nanoparticles was observed. The analyses allowed a quantitative evaluation of the evolution of the nanoparticles size, surface density, and shape as a function of the laser fluence. Therefore, a control the structural properties of the Au nanoparticles is reached, for example, for applications in Si nanowires growth or plasmonics.

Correlation of blister diameter and blister skin thickness in helium-ion-irradiated Nb

International Nuclear Information System (INIS)

Das, S.K.; Kaminsky, M.; Fenske, G.

1979-01-01

A systematic study of the correlation between blister diameter and blister skin thickness has been performed for helium-ion irradiation of monocrystalline and polycrystalline Nb for ion energies ranging from 20 to 500 keV. The results indicate that a relationship Datsub mpatproportionaltatsup 1.50at between the most probable blister diameter, Datsub mpat, and blister skin thickness, t, which has been suggested by other authors, does not exist for the various types of Nb targets studied. For example, for room-temperature irradiation of annealed polycrystalline Nb the experimentally determined relationship is Datsub mpat<10.3tatsup 1.22at. Furthermore, the D-t relationship was found to depend on the irradiation temperature in contrast to theoretical predictions by the lateral stress model of blister formation. These results do not appear to support the lateral stress model which predicts the relationship Dproportionaltatsup 1.5at. However, the experimentally determined relationships can be explained in part by the gas pressure model of blister formation

Laser application for nuclear reaction product detecting system alignment

International Nuclear Information System (INIS)

Grantsev, V.I.; Dryapachenko, I.P.; Kornilov, V.A.; Nemets, O.F.; Rudenko, B.A.; Sokolov, M.V.; Struzhko, B.G.; Gnatovskij, A.V.; Bojchuk, V.N.

1982-01-01

A method for optical alignment of nuclear particle detector system using a laser beam and hologram is described. The method permits to arrange detectors very precisely in accordance with any chosen space coordinate values. The results of modelling the geometry of an experiment based on using the suggested method on cyclotron beams are described. A gas helium-neon laser with wavelength of 0.63 μm radiation power of an order of 2 MW and angular beam divergence less than 10 angular minutes is used for modelling. It is concluded that the laser and hologram application provides large possibilities for the modelling the geometry of experiments on nuclear reaction investigation. When necessary it is possible to obtain small nonius scale of reference beams by means of multiplicating properties of the wave front modulator-hologram system. It is also possible to record holograms shaping the reference beams in two or several planes crossing along the central beam direction. Such holograms can be used for modelling the noncoplanar geometry of correlation experiments [ru

On the empirical determination of positron trapping coefficient at nano-scale helium bubbles in steels irradiated in spallation target

Science.gov (United States)

Krsjak, Vladimir; Kuriplach, Jan; Vieh, Christiane; Peng, Lei; Dai, Yong

2018-06-01

In the present work, the specific positron trapping rate of small helium bubbles was empirically derived from positron annihilation lifetime spectroscopy (PALS) and transmission electron microscopy (TEM) studies of Fe9Cr martensitic steels. Both techniques are well known to be sensitive to nanometer-sized helium-filled cavities induced during irradiation in a mixed proton-neutron spectrum of spallation target. Complementary TEM and PALS studies show that positrons are being trapped to these defects at a rate of 1.2 ± 0.8 × 10-14 m3s-1. This suggests that helium bubbles in ferritic/martensitic steels are attractive traps for positrons comparable to mono-vacancies and quantitative analysis of the bubbles by PALS technique is plausible.

Out-pile Test of Double Cladding Fuel Rod Mockups for a Nuclear Fuel Irradiation Test

Energy Technology Data Exchange (ETDEWEB)

Sohn, Jaemin; Park, Sungjae; Kang, Younghwan; Kim, Harkrho; Kim, Bonggoo; Kim, Youngki [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of)

2008-05-15

An instrumented capsule for a nuclear fuel irradiation test has been developed to measure fuel characteristics, such as a fuel temperature, internal pressure of a fuel rod, a fuel pellet elongation and a neutron flux during an irradiation test at HANARO. In the future, nuclear fuel irradiation tests under a high temperature condition are expected from users. To prepare for this request, we have continued developing the technology for a high temperature nuclear fuel irradiation test at HANARO. The purpose of this paper is to verify the possibility that the temperature of a nuclear fuel can be controlled at a high temperature during an irradiation test. Therefore we designed and fabricated double cladding fuel rod mockups. And we performed out-pile tests using these mockups. The purposes of a out-pile test is to analyze an effect of a gap size, which is between an outer cladding and an inner cladding, on the temperature and the effect of a mixture ratio of helium gas and neon gas on the temperature. This paper presents the design and fabrication of double cladding fuel rod mockups and the results of the out-pile test.

Microstructural design of PCA austenitic stainless steel for improved resistance to helium embrittlement under HFIR irradiation

International Nuclear Information System (INIS)

Maziasz, P.J.; Braski, D.N.

1983-01-01

Several variants of Prime Candidate Alloy (PCA) with different preirradiation thermal-mechanical treatments were irradiated in HFIR and were evaluated for embrittlement resistance via disk-bend tensile testing. Comparison tests were made on two heats of 20%-cold-worked type 316 stainless steel. None of the alloys were brittle after irradiation at 300 to 400 0 C to approx. 44 dpa and helium levels of 3000 to approx.3600 at. ppm. However, all were quite brittle after similar exposure at 600 0 C. Embrittlement varied with alloy and pretreatment for irradiation to 44 dpa at 500 0 C and to 22 dpa at 600 0 C. Better relative embrittlement resistance among PCA variants was found in alloys which contained prior grain boundary MC carbide particles that remained stable under irradiation

Studies on the separation of hydrogen isotopes and spin isomers by gas chromatography

International Nuclear Information System (INIS)

Pushpa, K.K.; Annaji Rao, K.

2000-08-01

Separation and analysis of mixture of hydrogen isotopes has gained considerable importance because of various applications needing different isotopes in lasers, nuclear reactions and tracer or labelled compounds. In the literature gas chromatographic methods are reported using columns packed with partly dehydrated or thoroughly dehydrated alumina/molecular sieve stationary phase at 77 deg K with helium, neon and even hydrogen or deuterium as carrier gas. In the present study an attempt is made to compare the chromatographic behaviour of these two stationary phases using virgin and Fe doped form in partly dehydrated and thoroughly dehydrated state, using helium, neon, hydrogen and deuterium as carrier gas. The results of this study show that helium or neon carrier gas behave similarly broad peaks with some tailing. Sharp symmetric peaks are obtained with hydrogen or deuterium carrier gas. This is attributed to large hold up capacity for H 2 or D 2 at 77 deg K in these materials as compared to helium or neon. Spin isomers of H 2 or D 2 are separated on Fe free stationary phases, though ortho H 2 and HD are not resolved. Using a combination of Fe doped short column and plain alumina column, both maintained in dehydrated form, the effect of Fe doping on thermal equilibrium of ortho/para forms at 77 deg K is clearly demonstrated. (author)

Interaction of intense ultrashort pulse lasers with clusters

International Nuclear Information System (INIS)

Petrov, G. M.; Davis, J.

2008-01-01

The dynamics of clusters composed of different material irradiated by a high-intensity ultrashort pulse laser was studied using a fully relativistic three-dimensional molecular dynamics model. Key parameters of the cluster evolution such as particle positions, energy absorption, and cluster explosion were simulated. By a direct comparison of these parameters for clusters of equal initial radius but made of different material (deuterium, neon, argon, and xenon), the main stages and attributes of cluster evolution were elucidated. The simulations showed that clusters made of different material act alike, especially those of heavy elements. Clusters made of heavy elements (neon, argon, and xenon) differentiate from clusters made of light elements (deuterium) by the magnitude of the absorbed energy per cluster and the final mean energy of exploding ions. What most distinguishes clusters composed of different material is the amount of emitted radiation and its spectral range

Negative pion trapping by metastable state in liquid helium

International Nuclear Information System (INIS)

Nakamura, S.N.; Iwasaki, M.; Outa, H.

1991-11-01

We found long-lived metastable states of stopped π - 's in liquid helium by measuring time spectra of two different delayed products: 1) protons emitted after π - absorption by 4 He nuclei and 2) 70-MeV electrons originating from free π - → e - (ν e )-bar decay. The lifetime and fraction of delayed π - absorption obtained by emitted protons are 7.26±0.12 nsec and 1.66±0.05%, respectively. The free-decay fraction was calculated to be 0.64±0.03% from this result, which is consistent with the observed free-decay fraction of π e2 decay. These results imply that 2.30±0.07% of stopped π - are trapped in metastable states which have an overall lifetime of 10.1±0.2 nsec. The same experiment and analysis were performed for stopped π - in liquid neon. No evidence for trapping was found in liquid neon. (author)

Characterization of laser ablation of copper in the irradiance regime of laser-induced breakdown spectroscopy analysis

Energy Technology Data Exchange (ETDEWEB)

Picard, J., E-mail: jessica.picard@cea.fr [Commissariat à l' Energie Atomique, DAM, Valduc, F-21120 Is-sur-Tille (France); Sirven, J.-B.; Lacour, J.-L. [Commissariat à l' Energie Atomique, DEN/DANS/DPC/SEARS/LANIE, Saclay, F-91191 Gif-sur-Yvette (France); Musset, O. [Université de Bourgogne, Laboratoire Interdisciplinaire Carnot de Bourgogne, UMR CNRS 5209, F-21000 Dijon (France); Cardona, D.; Hubinois, J.-C. [Commissariat à l' Energie Atomique, DAM, Valduc, F-21120 Is-sur-Tille (France); Mauchien, P. [Commissariat à l' Energie Atomique, DEN/DANS/DPC/SEARS/LANIE, Saclay, F-91191 Gif-sur-Yvette (France)

2014-11-01

The LIBS signal depends both on the ablated mass and on the plasma excitation temperature. These fundamental parameters depend in a complex manner on laser ablation and on laser–plasma coupling. As several works in the literature suggest that laser ablation processes play a predominant role compared to plasma heating phenomena in the LIBS signal variations, this paper focuses on the study of laser ablation. The objective was to determine an interaction regime enabling to maximally control the laser ablation. Nanosecond laser ablation of copper at 266 nm was characterized by scanning electron microscopy and optical profilometry analysis, in air at 1 bar and in the vacuum. The laser beam spatial profile at the sample surface was characterized in order to give realistic values of the irradiance. The effect of the number of accumulated laser shots on the crater volume was studied. Then, the ablation crater morphology, volume, depth and diameter were measured as a function of irradiance between 0.35 and 96 GW/cm². Results show that in the vacuum, a regular trend is observed over the whole irradiance range. In air at 1 bar, below a certain irradiance, laser ablation is very similar to the vacuum case, and the ablation efficiency of copper was estimated at 0.15 ± 0.03 atom/photon. Beyond this irradiance, the laser beam propagation is strongly disrupted by the expansion of the dense plasma, and plasma shielding appears. The fraction of laser energy used for laser ablation and for plasma heating is estimated in the different irradiance regimes. - Highlights: • The morphology of copper's craters was studied as a function of the pulse energy. • Correlation at low energy and two pressures between crater volume and pulse energy • The ablation efficiency of copper at 1 bar is equal to 0.15 atom/photon. • Ablation efficiency in the vacuum is not limited by laser–plasma interaction. • Physical mechanisms of laser ablation at both pressures are discussed.

High resolution n = 3 to n = 2 spectra of neon-like silver

International Nuclear Information System (INIS)

Beiersdorfer, P.; Bitter, M.; von Goeler, S.

1986-04-01

Spectra of the n = 3 to n = 2 transitions in neon-like silver emitted from the Princeton Large Torus have been recorded with a high-resolution Bragg-crystal spectrometer. The measurements cover the wavelength region 3.3 to 4.1 A and include the forbidden 3p → 2p electric quadrupole lines. Transitions in the adjacent sodium-like, and aluminum-like charge states of silver have also been observed and identified. The Ly-α spectra of hydrogen-like argon and iron, the Kα spectra of helium-like argon, potassium, manganese, and iron, and the Kβ spectrum of helium-like argon fall in the same wavelength region in first or second order and have been measured concurrently. These spectra provide a coherent set of wavelength reference data obtained with the same spectrometer and from the same tokamak. This set is used as a basis to compare wavelength predictions for one- and two-electron systems to each other and to determine the transition energies of the silver lines with great accuracy

Relation between the conditions of helium ion implantation and helium void equilibrium parameters

International Nuclear Information System (INIS)

Neklyudov, I.M.; Rybalko, V.F.; Ruzhitskij, V.V.; Tolstolutskaya, G.D.

1981-01-01

The conditions of helium thermodynamic equilibrium in a system of voids produced by helium ion bombardment of a metal sample are studied. As an initial equation for description of the equilibrium the Clapeyron equation was used. The equation is obtained relating basic parameters of helium voids (average diameter and density) to irradiation parameters (dose, ion energy (straggling)) and properties of the metal (surface tension coefficient, yield strength). Comparison of the calculations with experimental data on helium in nickel found in literature shows that the equation yields satisfactory resutls for the dose range 1.10 16 -1x10 17 cm -2 and temperatures T [ru

Heat profiles of laser-irradiated nails.

Science.gov (United States)

Paasch, Uwe; Nenoff, Pietro; Seitz, Anna-Theresa; Wagner, Justinus A; Kendler, Michael; Simon, Jan C; Grunewald, Sonja

2014-01-01

Onychomycosis is a worldwide problem with no tendency for self-healing, and existing systemic treatments achieve disease-free nails in only 35 to 76% of cases. Recently, treatment of nail fungus with a near-infrared laser has been introduced. It is assumed that fungal eradication is mediated by local heat. To investigate if laser treatment has the potential to eradicate fungal hyphae and arthrospores, laser heat application and propagation needs to be studied in detail. This study aimed to measure nail temperatures using real-time videothermography during laser irradiation. Treatment was performed using 808- and 980-nm linear scanning diode lasers developed for hair removal, enabling contact-free homogeneous irradiation of a human nail plate in one pass. Average and peak temperatures increased pass by pass, while the laser beam moved along the nail plates. The achieved mean peak temperatures (808 nm: 74.1 to 112.4°C, 980 nm: 45.8 to 53.5°C), as well as the elevation of average temperatures (808 nm: 29.5 to 38.2°C, 980 nm: 27.1 to 32.6°C) were associated with pain that was equivalent to that of hair removal procedures and was not significantly different for various wavelengths. The linear scanning laser devices provide the benefits of contact-free homogeneous heating of the human nail while ensuring adequate temperature rises.

The Creation and Varied Applications of Educational Holograms.

Science.gov (United States)

Layng, Jacqueline M.

The potential of holograms has been left virtually untapped in the field of education. A hologram can be described as a three-dimensional photographic record of the interference pattern of two superimposed beams of coherent light. Holography requires: (1) high-resolution film; (2) a laser, often a red-beamed helium neon laser; (3) optical…

Femtosecond laser irradiation-induced infrared absorption on silicon surfaces

Directory of Open Access Journals (Sweden)

Qinghua Zhu

2015-04-01

Full Text Available The near-infrared (NIR absorption below band gap energy of crystalline silicon is significantly increased after the silicon is irradiated with femtosecond laser pulses at a simple experimental condition. The absorption increase in the NIR range primarily depends on the femtosecond laser pulse energy, pulse number, and pulse duration. The Raman spectroscopy analysis shows that after the laser irradiation, the silicon surface consists of silicon nanostructure and amorphous silicon. The femtosecond laser irradiation leads to the formation of a composite of nanocrystalline, amorphous, and the crystal silicon substrate surface with microstructures. The composite has an optical absorption enhancement at visible wavelengths as well as at NIR wavelength. The composite may be useful for an NIR detector, for example, for gas sensing because of its large surface area.

New technique for enhancing helium production in ferritic materials

International Nuclear Information System (INIS)

Greenwood, L.R.; Graczyk, D.G.; Kneff, D.W.

1987-10-01

Analyses of iron samples irradiated up to 10 27 n/m 2 in HFIR found more helium than was expected from fast neutron reactions at high neutron fluences. The helium excess increases systematically with neutron exposure, suggesting a transmutation-driven process. The extra helium may be produced in two different ways, either by fast neutron reactions on the transmuted isotopes of iron or by a thermal neutron reaction with the radioactive isotope 55 Fe. Radiometric and mass spectrometric measurements of the iron isotopes composing the irradiated samples have been used to determine limits on the cross sections for each process. Either of these processes can be used to enhance helium production in ferritic materials during irradiations in mixed-spectrum reactors by isotopically enriching the samples. Further work is needed to clarify the reaction mechanisms and helium production cross sections. Our measurements determined the thermal neutron total absorption cross section of 55 Fe to be 13.2 +- 2.1 barns. 16 refs., 3 figs., 3 tabs

Role of laser fluence in protein synthesis of cultured DRG neurons following low-level laser irradiation

Science.gov (United States)

Zheng, Liqin; Qiu, Caimin; Wang, Yuhua; Zeng, Yixiu; Yang, Hongqin; Zhang, Yanding; Xie, Shusen

2014-11-01

Low-level lasers have been used to relieve pain in clinical for many years. But the mechanism is not fully clear. In animal models, nitric oxide (NO) has been reported involving in the transmission and modulation of nociceptive signals. So the objective of this study was to establish whether low-level laser with different fluence could stimulate the production of nitric oxide synthese (NOS), which produces NO in cultured primary dorsal root ganglion neurons (DRG neurons). The primary DRG neurons were isolated from healthy Sprague Dawley rats (8-12 weeks of age) and spread on 35 mm culture dishes specially used for confocal microscopy. 24 hours after spreading, cells were irradiated with 658 nm laser for two consecutive days at the energy density of 20, 40, 60 and 80 mJ·cm-2 respectively. Control groups were not exposed to the laser, but were kept under the same conditions as the irradiated ones. The synthesis of NOS after laser irradiation was detected by immunofluorescence assay, and the changes of NOS were evaluated using confocal microscopy and Image J software. The results showed that all the laser fluence could promote the production of NOS in DRG neurons, especially the 60 mJ·cm-2 . These results demonstrated that low-level laser irradiation could modify protein synthesis in a dose- or fluence- dependent manner, and indicated that low-level laser irradiation might achieve the analgesic effect through modulation of NO production.

Helium behaviour in aluminium under hydrostatic pressure

International Nuclear Information System (INIS)

Sokurskij, Yu.N.; Tebus, V.N.; Zudilin, V.A.; Tumanova, G.M.

1989-01-01

Effect of hydrostatic compression on equilibrium helium bubbles in low aluminium-lithium alloy irradiated in reactor at 570 K is investigated. Measurements of hydrostatic density and electron-microscopic investigations have shown, that application of up to 2 GPa pressure reduces equilibrium size of helium bubbles and reduces helium swelling. Kinetics and thermodynamics of the process are considered with application of 'rigid sphere' equation which describes helium state in bubbles

An investigation of the electron irradiation of graphite in a helium atmosphere using a modified electron microscope

International Nuclear Information System (INIS)

Burden, A.P.; Hutchison, J.L.

1997-01-01

The behaviour of graphite particles immersed in helium gas and irradiated with an electron-beam has been investigated. Because this treatment was performed in a modified high resolution transmission electron microscope, the rapid morphological and microstructural changes that occurred could be directly observed. The results have implications for future controlled environment microscopy of carbonaceous materials and the characterisation of such microscopes. It is also shown that the processes can provide insight into ion-irradiation induced damage of graphite and the mechanism of fullerene generation. (Author)

Small-scale heat detection using catalytic microengines irradiated by laser

Science.gov (United States)

Liu, Zhaoqian; Li, Jinxing; Wang, Jiao; Huang, Gaoshan; Liu, Ran; Mei, Yongfeng

2013-01-01

We demonstrate a novel approach to modulating the motion speed of catalytic microtubular engines via laser irradiation/heating with regard to small-scale heat detection. Laser irradiation on the engines leads to a thermal heating effect and thus enhances the engine speed. During a laser on/off period, the motion behaviour of a microengine can be repeatable and reversible, demonstrating a regulation of motion speeds triggered by laser illumination. Also, the engine velocity exhibits a linear dependence on laser power in various fuel concentrations, which implies an application potential as local heat sensors. Our work may hold great promise in applications such as lab on a chip, micro/nano factories, and environmental detection.We demonstrate a novel approach to modulating the motion speed of catalytic microtubular engines via laser irradiation/heating with regard to small-scale heat detection. Laser irradiation on the engines leads to a thermal heating effect and thus enhances the engine speed. During a laser on/off period, the motion behaviour of a microengine can be repeatable and reversible, demonstrating a regulation of motion speeds triggered by laser illumination. Also, the engine velocity exhibits a linear dependence on laser power in various fuel concentrations, which implies an application potential as local heat sensors. Our work may hold great promise in applications such as lab on a chip, micro/nano factories, and environmental detection. Electronic supplementary information (ESI) available. See DOI: 10.1039/c2nr32494f

Argon laser irradiation of the otolithic organ

Energy Technology Data Exchange (ETDEWEB)

Okuno, T.; Nomura, Y.; Young, Y.H.; Hara, M. (Univ. of Tokyo (Japan))

1990-12-01

An argon laser was used to irradiate the otolithic organs of guinea pigs and cynomolgus monkeys. After stapedectomy, the argon laser (1.5 W x 0.5 sec/shot) irradiated the utricle or saccule without touching the sensory organs. The stapes was replaced over the oval window after irradiation. The animals used for acute observation were killed immediately for morphologic studies; those used for long-term observation were kept alive for 2, 4, or 10 weeks. Acute observation revealed that sensory and supporting cells were elevated from the basement membrane only in the irradiated area. No rupture of the membranous labyrinth was observed. Long-term observation revealed that the otolith of the macula utriculi had disappeared in 2-week specimens. The entire macula utricili had disappeared in 10-week specimens. No morphologic changes were observed in cochlea, semicircular canals, or membranous labyrinth. The saccule showed similar changes.

Helium effects on tungsten surface morphology and deuterium retention

International Nuclear Information System (INIS)

Ueda, Y.; Peng, H.Y.; Lee, H.T.; Ohno, N.; Kajita, S.; Yoshida, N.; Doerner, R.; De Temmerman, G.; Alimov, V.; Wright, G.

2013-01-01

Recent experimental results on tungsten surface morphology, especially nano-structure (fuzz), induced by helium plasma exposure at temperatures between 1000 K and 2000 K are reviewed. This structure was firstly reported in 2006. In this review, most of experimental results reported so far including characteristics and formation conditions of the nano-structure in both linear plasma devices and magnetic confinement devices, erosion and arcing by steady-state plasma exposure and ELM-like pulsed heat or pulsed plasma exposure by a laser and a plasma gun are summarized. In addition, He effects on D retention under simultaneous D/He irradiation on tungsten are presented

Intensity dependence of nonsequential double ionization of helium in IR+XUV two-color laser fields

International Nuclear Information System (INIS)

Jin, Facheng; Wang, Bingbing; Chen, Jing; Yang, Yujun; Yan, Zong-Chao

2016-01-01

By applying the frequency-domain theory, we investigate the dependence of momentum spectra on laser intensity in a nonsequential double ionization (NSDI) process of helium in infrared (IR) and extreme ultraviolet (XUV) two-color laser fields. We find that the two-color laser fields play distinct roles in an NSDI process, where the IR laser field mainly determines the width of each band, and the XUV laser field mainly plays a role on the NSDI probability. Furthermore, an NSDI process can be decoupled into a two-step process: an above-threshold ionization (ATI), followed by a laser-assisted collision (LAC). It is found that, the IR laser field is responsible for broadening the peak in the ATI process and providing additional momenta to the two ionized electrons in the LAC process; while the XUV laser field plays a crucial role on the strength of the spectrum in the ATI process, and influences the radii of orbits in momentum space in the LAC process. (paper)

Laser spectroscopy of Ag atoms in liquid helium and gaseous helium at low temperatures

International Nuclear Information System (INIS)

Hui, Q.; Persson, J. L.; Jakubek, Z. J.; Takami, M.

1998-01-01

Neutral Ag atoms are dispersed in liquid and gaseous helium by laser ablation and dissociation. Following the excitation of the D2 line, a broad emission band is observed to the red side of the D1 emission line. This band is assigned to the A 2 Π 3/2 → X 2 Σ + bound-free transition of the AgHe 2 exciplex. The assignment has been confirmed by an ab initio calculation on the AgHe 2 complex. The temperature and the pressure dependences of the D1 emission and the broad emission in the gas phase indicate that the 4d 9 5s 2 2 D 5/2 level may play an important role in the 5p 2 P 3/2 → 5p 2 1/2 non-radiative relaxation and the exciplex formation processes

Collisional interaction between metastable neon atoms

Energy Technology Data Exchange (ETDEWEB)

Drunen, Wouter Johannes van

2008-07-07

In this thesis, the study of cold gases of neon atoms in different metastable states is described. It contains measurements of the collisional parameters for both the 3s[3/2]{sub 2} and the 3s'[1/2]{sub 0} metastable state and the dependence of the inelastic loss on external fields. Furthermore, the investigation of frequency dependent laser-induced collisions, and the possibility to excite photoassociation resonances is presented. For the measurements described here, neon atoms have been confined in a magnetooptical trap, in a magnetostatic trap, or in an optical dipole trap, respectively. By laser cooling inside the magnetic trap, atomic samples with more than 95 percent occupation of the magnetic substate m{sub J} = +2 could be prepared. They have a typical temperature of 0.5 mK, central densities up to 10{sup 11} cm{sup -3}, and a central phase-space density of up to 2.2.10{sup -7}. After loading the optical dipole trap from the magnetic trap, 2.5.10{sup 6} atoms with typical temperatures of 0.1 mK, and central densities up to 5.10{sup 10} cm{sup -3} were trapped. By evaporative cooling of the atoms in the magnetic trap we could increase the phase-space density by a factor of 200 to 5.10{sup -5}. Investigating the frequency dependence of laser-induced collisions did not reveal an experimental signature for the excitation of photoassociation resonances. For the {sup 3}D{sub 3} line a frequency dependence of laser enhanced Penning ionization was observed. Measurement of the two-body loss coefficient as function of the magnetic field showed a field dependence of the inelastic loss. These losses increase towards both small and large offset fields. The implementation of an optical dipole trap allowed us to trap the {sup 3}P{sub 0} metastable state. From the trap loss measurements we determined the two-body loss coefficient of the {sup 3}P{sub 0} metastable state for both bosonic isotopes {sup 20}Ne and {sup 22}Ne. For {sup 20}Ne we obtained {beta}=6{sup +5}{sub

Residual stress improvement mechanism on metal material by underwater laser irradiation

International Nuclear Information System (INIS)

Sano, Yuji; Yoda, Masaki; Mukai, Naruhiko; Obata, Minoru; Kanno, Masanori

2000-01-01

Residual stress improvement technology for component surface by underwater pulsed laser irradiation has been developed as a method of preventing stress corrosion cracking (SCC) of core components in nuclear reactors. In order to optimize the laser irradiation conditions based on a complete understanding of the mechanism, the propagation of a shock wave induced by the impulse of laser irradiation and the dynamic response of the irradiated material were analyzed through time-dependent elasto-plastic calculations with a finite element program. The calculated results are compared with the measured results obtained by experiments in which laser pulses with an energy of 200 mJ are focused to a diameter of 0.8 mm on a water-immersed test piece of 20% cold-worked Type 304 austenitic stainless steel to simulate neutron irradiation hardening. A residual compressive stress, which is nearly equivalent to the yield stress of the processed material, remains on the material surface after passage of the shock wave with enough amplitude to induce a permanent strain. Multiple irradiation of laser pulses extends the stress-improved depth to about 1 mm, which would be the limit corresponding to the three-dimensional dispersion effect of the shock wave. (author)

A metastable helium trap for atomic collision physics

International Nuclear Information System (INIS)

Colla, M.; Gulley, R.; Uhlmann, L.; Hoogerland, M.D.; Baldwin, K.G.H.; Buckman, S.J.

1999-01-01

Full text: Metastable helium in the 2 3 S state is an important species for atom optics and atomic collision physics. Because of its large internal energy (20eV), long lifetime (∼8000s) and large collision cross section for a range of processes, metastable helium plays an important role in atmospheric physics, plasma discharges and gas laser physics. We have embarked on a program of studies on atom-atom and electron-atom collision processes involving cold metastable helium. We confine metastable helium atoms in a magneto-optic trap (MOT), which is loaded by a transversely collimated, slowed and 2-D focussed atomic beam. We employ diode laser tuned to the 1083 nm (2 3 S 1 - 2 3 P2 1 ) transition to generate laser cooling forces in both the loading beam and the trap. Approximately 10 million helium atoms are trapped at temperatures of ∼ 1mK. We use phase modulation spectroscopy to measure the trapped atomic density. The cold, trapped atoms can collide to produce either atomic He + or molecular He 2 + ions by Penning Ionisation (PI) or Associative Ionisation (AI). The rate of formation of these ions is dependant upon the detuning of the trapping laser from resonance. A further laser can be used to connect the 2 3 S 1 state to another higher lying excited state, and variation of the probe laser detuning used to measure interatomic collision potential. Electron-atom collision processes are studied using a monochromatic electron beam with a well defined spatial current distribution. The total trap loss due to electron collisions is measured as a function of electron energy. Results will be presented for these atomic collision physics measurements involving cold, trapped metastable helium atoms. Copyright (1999) Australian Optical Society

Magnetic resonance thermometry for monitoring photothermal effects of interstitial laser irradiation

Science.gov (United States)

Goddard, Jessica; Jose, Jessnie; Figueroa, Daniel; Le, Kelvin; Liu, Hong; Nordquist, Robert E.; Hode, Tomas; Chen, Wei R.

2012-03-01

Selective photothermal interaction using dye-assisted non-invasive laser irradiation has limitations when treating deeper tumors or when the overlying skin is heavily pigmented. We developed an interstitial laser irradiation method to induce the desired photothermal effects. An 805-nm near-infrared laser with a cylindrical diffuser was used to treat rat mammary tumors by placing the active tip of the fiber inside the target tumors. Three different power settings (1.0 to 1.5 watts) were applied to treat animal tumors with an irradiation duration of 10 minutes. The temperature distributions of the treated tumors were measured by a 7.1-Tesla magnetic resonance imager using proton resonance frequency (PRF) method. Three-dimensional temperature profiles were reconstructed and assessed using PRF. This is the first time a 7.1-Tesla magnetic resonance imager has been used to monitor interstitial laser irradiation via PRF. This study provides a basic understanding of the photothermal interaction needed to control the thermal damage inside tumor using interstitial laser irradiation. It also shows that PRF can be used effectively in monitoring photothermal interaction. Our long-term goal is to develop a PRF-guided laser therapy for cancer treatment.

Combination closed-cycle refrigerator/liquid-He4 cryostat for e- damage of bulk samples

International Nuclear Information System (INIS)

Johnson, E.C.

1987-01-01

A closed-cycle refrigerator/cryostat system for use in ultrasonic studies of electron irradiation damaged bulk specimens is described. The closed-cycle refrigerator provides a convenient means for long-term (several days) sample irradiation at low temperatures. A neon filled ''thermal diode'' is employed to permit efficient cooling, via liquid helium, of the sample below the base temperature of the refrigerator

Flickering light a history of neon

CERN Document Server

Ribbat, Christoph

2013-01-01

Without neon, Las Vegas might still be a sleepy desert town in Nevada and Times Square merely another busy intersection in New York City. Transformed by the installation of these brightly colored signs, these destinations are now world-famous, representing the vibrant heart of popular culture. But for some, neon lighting represents the worst of commercialism. Energized by the conflicting love and hatred people have for neon, Flickering Light explores its technological and intellectual history, from the discovery of the noble gas in late nineteenth-century London to its fading popul

Laser cutting equipment for dismantling irradiated PFR fuel sub-assemblies

International Nuclear Information System (INIS)

Higginson, P.R.; Campbell, D.A.

1981-01-01

Laser cutting was identified as a possible technique for dismantling irradiated Prototype Fast Reactor (P.F.R.) fuel sub-assemblies and initial trials showed that it could be used to make essentially swarf free cuts in P.F.R. wrapper material provided sufficient laser power was available to allow use of an inert cutting gas. A programme of development work has established a technique for inert gas cutting with the reliable, commercially available Ferranti MF 400 laser and equipment for laser cutting of sub-assemblies has been installed in the Irradiated Fuel Cave at P.F.R. Test cuts carried out with this equipment on un-irradiated wrapper sections have shown it to be easy to operate remotely, optically stable and reliable in operation. (author)

Thermal Changes of Maize Seed by Laser Irradiation

Science.gov (United States)

Hernandez-Aguilar, C.; Dominguez-Pacheco, A.; Cruz-Orea, A.

2015-09-01

In this research, the thermal evolution in maize seeds ( Zea mays L.) was studied when low-intensity laser irradiation was applied during 60 s. The seeds were irradiated in three different conditions: suspended in air, placed on an aluminum surface, and finally placed on a cardboard; the evolution of the seed temperature was measured by an infrared camera. Photoacoustic spectroscopy and the Rosencwaig and Gersho model were used to determine the optical absorption coefficient (β ) of the seeds. The results indicate that using 650 nm laser light and 27.4 mW, it is possible to produce temperature changes (up to 9.06°C after 1 min) on the seeds. Comparing the mean temperature of the seeds, during and after the incidence of light from a laser, it was found that there were statistically significant differences (P≤ 0.05) from time t1 to time t_{16} (t1 to t_{16}) and t3 to t_{16}, for the laser turned on and off, respectively. The seed condition that had the highest temperature variation, relative to the initial temperature (during the irradiation laser exposure), involved the seeds suspended in air. With regard to the stage of decay of the temperature, it was found that the seed condition that decays more slowly was the seed placed on the cardboard. It was also found that black-dyed maize seeds are optically opaque in the 300 nm to 700 nm range Also, the thermal diffusion length is smaller than the optical penetration length. In the present investigation, it was shown that there is a thermal component associated with the mechanisms of laser biostimulation, which is also a function of the container materials of the seed. In this way, the effects of laser treatment on maize seeds involve at least a temperature effect. It is important to know the temperature changes in the seeds that have been irradiated with a laser beam since they could have substantial practical and theoretical importance.

The study on the electrical resistivity of Cu/V multilayer films subjected to helium (He) ion irradiation

Science.gov (United States)

Wang, P. P.; Xu, C.; Fu, E. G.; Du, J. L.; Gao, Y.; Wang, X. J.; Qiu, Y. H.

2018-05-01

Sputtering-deposited Cu/V multilayer films with the individual layer thickness varying from 2.5 nm to 100 nm were irradiated by 1 MeV helium (He) ion at the fluence of 6 ×1016 ions ·cm-2 at room temperature. The resistivity of Cu/V multilayer films after ion irradiation was evaluated as a function of individual layer thickness at 300 K and compared with their resistivity before ion irradiation. The results show that the resistivity change before and after ion irradiation is largely determined by the interface structure, grain boundary and radiation induced defects. A model amended based on the model used in describing the resistivity of as-deposited Cu/V multilayer films was proposed to describe the resistivity of ion irradiated Cu/V multilayer films by considering the point defects induced by ion irradiation, the effect of interface absorption on defects and the effect of interface microstructure in the multilayer films.

Study of helium and beryllium atoms with strong and short laser field; Etude des atomes d'helium et de beryllium en champ laser intense et bref

Energy Technology Data Exchange (ETDEWEB)

Laulan, St

2004-09-01

We present a theoretical study of the interaction between a two-active electron atom and an intense (10{sup 14} to 10{sup 15} W/cm{sup 2}) and ultrashort (from a few 10{sup -15} to a few 10{sup -18} s) laser field. In the first part, we describe the current experimental techniques able to produce a coherent radiation of high power in the UV-XUV regime and with femtosecond time duration. A theoretical model of a laser pulse is defined with such characteristics. Then, we develop a numerical approach based on B-spline functions to describe the atomic structure of the two-active electron system. A spectral non perturbative method is proposed to solve the time dependent Schroedinger equation. We focalize our attention on the description of the atomic double continuum states. Finally, we expose results on the double ionization of helium and beryllium atoms with intense and short laser field. In particular, we present total cross section calculations and ejected electron energy distributions in the double continuum after one- and two-photon absorption. (author)

Reactions of laser-ablated iron atoms and cations with carbon monoxide: Infrared spectra of FeCO+, Fe(CO)2+, Fe(CO)x, and Fe(CO)x- (x=1-4) in solid neon

Science.gov (United States)

Zhou, Mingfei; Andrews, Lester

1999-06-01

Laser-ablated iron atoms, cations, and electrons have been reacted with CO molecules during condensation in excess neon. The FeCO molecule is observed at 1933.7 cm-1 in solid neon. Based on isotopic shifts and density functional calculations, the FeCO molecule has the same 3Σ- ground state in solid neon that has been observed at 1946.5 cm-1 in a recent high resolution gas phase investigation [Tanaka et al., J. Chem. Phys. 106, 2118 (1997)]. The C-O stretching vibration of the Fe(CO)2 molecule is observed at 1917.1 cm-1 in solid neon, which is in excellent agreement with the 1928.2 cm-1 gas phase value for the linear molecule. Anions and cations are also produced and trapped, absorptions at 1782.0, 1732.9, 1794.5, and 1859.7 cm-1 are assigned to the linear FeCO-, Fe(CO)2-, trigonal planar Fe(CO)3-, and C3v Fe(CO)4- anions, respectively, and 2123.0, 2134.0 cm-1 absorptions to the linear FeCO+ and Fe(CO)2+ cations. Doping these experiments with CCl4 virtually eliminates the anion absorptions and markedly increases the cation absorptions, which confirms the charge identifications. Higher iron carbonyl Fe(CO)3, Fe(CO)4, and Fe(CO)5 absorptions are produced on photolysis.

Diagnosis of laser ablated carbon particles measured by time-resolved X-ray absorption spectroscopy

International Nuclear Information System (INIS)

Miyashita, Atsumi; Yoda, Osamu; Ohyanagi, T.; Murakami, K.

1995-01-01

The time and space resolved properties of laser ablated carbon particles were measured by X-ray absorption spectroscopy using LPX as an X-ray source. The energy density of the irradiation laser on the sample was in the range of 0.5-20J/cm 2 and the time delay was varied between 0 and 120ns. The absorption spectra exhibited several peaks originated from level to level transitions and an intense broad absorption in the energy range of C-K edge. At a delay time of 120ns, the absorption peak from 1s→2p transition of neutral carbon atom (C 0 ), C - , C + and C 2+ ions were observed. The absorption peak from C 0 was stronger as the probing position was closer to the sample surface and decreased rapidly with distance from the sample surface. The absorption peak C 2+ ion was observed only at comparatively distant positions from surface. The maximum speeds of highly charged ions were faster than that of neutral atoms and negative charged ions. The neutral atom and lower charged ions were emitted from the sample even after laser irradiation. The spatial distributions of the laser ablated carbon particles in the localized helium gas environment were measured. In the helium gas environment, the ablation plume was depressed by the helium cloud generated on the top of ablation plume. (author)

Method for mounting laser fusion targets for irradiation

Science.gov (United States)

Fries, R. Jay; Farnum, Eugene H.; McCall, Gene H.

1977-07-26

Methods for preparing laser fusion targets of the ball-and-disk type are disclosed. Such targets are suitable for irradiation with one or two laser beams to produce the requisite uniform compression of the fuel material.

Low- and high-dose laser irradiation effects on cell migration and destruction

Science.gov (United States)

Layton, Elivia; Gallagher, Kyra A.; Zukerman, Sara; Stevens, Brianna; Zhou, Feifan; Liu, Hong; Chen, Wei R.

2018-02-01

Metastases are the cause of more than 90 percent of cancer-related deaths. Current treatment methods, including chemotherapy, radiation, and surgery, fail to target the metastases effectively. One potential treatment for metastatic cancer is laser immunotherapy (LIT). LIT combines the use of a photothermal laser with an immunoadjuvant, Glycated Chitosan (GC). GC combined with single-walled carbon nanotubes (SWNTs) has proven to be a viable alternative to traditional cancer treatment methods, when under irradiation of laser with appropriate wavelength. In this study, the effects of low dose and high dose laser irradiation on metastatic pancreatic cancer cell migration were observed. It was found that low dose irradiation increased the migration rate, but the high dose irradiation significantly decreased the migration rate of the cancer cells. When using LIT, the goal is to kill tumor cells and to prompt the correct immune response. If the tumor were irradiated with a low dose, it would promote metastasis. If the dose of irradiation were too high, it would destroy the entire tumor and the immune response would not recognize the tumor. Therefore, the laser dose plays an important role in LIT, particularly when using SWNT as light absorbing agent. Our results from this study will delineate the optimal laser irradiation dose for destroying tumor cells and at the same time preserve and release tumor antigens as a precursor of antitumor immune response.

Simulation analysis of impulse characteristics of space debris irradiated by multi-pulse laser

Science.gov (United States)

Lin, Zhengguo; Jin, Xing; Chang, Hao; You, Xiangyu

2018-02-01

Cleaning space debris with laser is a hot topic in the field of space security research. Impulse characteristics are the basis of cleaning space debris with laser. In order to study the impulse characteristics of rotating irregular space debris irradiated by multi-pulse laser, the impulse calculation method of rotating space debris irradiated by multi-pulse laser is established based on the area matrix method. The calculation method of impulse and impulsive moment under multi-pulse irradiation is given. The calculation process of total impulse under multi-pulse irradiation is analyzed. With a typical non-planar space debris (cube) as example, the impulse characteristics of space debris irradiated by multi-pulse laser are simulated and analyzed. The effects of initial angular velocity, spot size and pulse frequency on impulse characteristics are investigated.

Effect of high power CO2 and Yb:YAG laser radiation on the characteristics of TIG arc in atmospherical pressure argon and helium

Science.gov (United States)

Wu, Shikai; Xiao, Rongshi

2015-04-01

The effects of laser radiation on the characteristics of the DC tungsten inert gas (TIG) arc were investigated by applying a high power slab CO2 laser and a Yb:YAG disc laser. Experiment results reveal that the arc voltage-current curve shifts downwards, the arc column expands, and the arc temperature rises while the high power CO2 laser beam vertically interacts with the TIG arc in argon. With the increase of the laser power, the voltage-current curve of the arc shifts downwards more significantly, and the closer the laser beam impingement on the arc to the cathode, the more the decrease in arc voltage. Moreover, the arc column expansion and the arc temperature rise occur mainly in the region between the laser beam incident position and the anode. However, the arc characteristics hardly change in the cases of the CO2 laser-helium arc and YAG laser-arc interactions. The reason is that the inverse Bremsstrahlung absorption coefficients are greatly different due to the different electron densities of the argon and helium arcs and the different wave lengths of CO2 and YAG lasers.

Influence of laser shock peening on irradiation defects in austenitic stainless steels

Science.gov (United States)

Lu, Qiaofeng; Su, Qing; Wang, Fei; Zhang, Chenfei; Lu, Yongfeng; Nastasi, Michael; Cui, Bai

2017-06-01

The laser shock peening process can generate a dislocation network, stacking faults, and deformation twins in the near surface of austenitic stainless steels by the interaction of laser-driven shock waves with metals. In-situ transmission electron microscopy (TEM) irradiation studies suggest that these dislocations and incoherent twin boundaries can serve as effective sinks for the annihilation of irradiation defects. As a result, the irradiation resistance is improved as the density of irradiation defects in laser-peened stainless steels is much lower than that in untreated steels. After heating to 300 °C, a portion of the dislocations and stacking faults are annealed out while the deformation twins remain stable, which still provides improved irradiation resistance. These findings have important implications on the role of laser shock peening on the lifetime extension of austenitic stainless steel components in nuclear reactor environments.

Helium cryosystem for the X-ray laser LCLS-II; Heliumkryosystem fuer den Roentgenlaser LCLS-II

Energy Technology Data Exchange (ETDEWEB)

Pflueckhahn, Dirk; Fauve, Eric; Heloin, Vincent; Ravindranath, Viswanath; Ross, Marc [SLAC National Accelerator Laboratory, Menlo Park, CA (United States)

2017-07-01

The Linac Coherent Light Source-II project represents the expansion of the LCLS free-electron laser, which has been successfully operated at the SLAC National Accelerator Laboratory since 2009. In collaboration with several national institutes, 37 cryomodules with superconducting accelerator cavities will be installed in a 700 m long section of the existing tunnel. The use of superconducting accelerator technology will enable particle energy of up to 4 GeV in CW (continuous wave) operation. Two identical cryogenic systems with an equivalent output of 18 kW each at 4.5 K are described below. The plants supply the linear accelerator with helium at several temperature levels. Superfluid helium II provides the cooling necessary to maintain superconductivity in the cavities. The operating temperature of the 1.3 GHz cavities has been set at 2 K. Two further helium circuits are used for shield cooling at approx. 35 K and cooling of heat loads at 5 K level. The purely dynamic compression of the cold helium vapour is a technical feature of the systems described here. In a five-stage chain of cold compressors of 32 mbar at the cavities, it is absolutely compressed to the suction pressure of the circulation compressors at approx. 1 bar. [German] Das Linac Coherent Light Source-II Projekt stellt die Erweiterung des seit 2009 erfolgreich betriebenen Freie- Elektronen-Lasers LCLS am SLAC National Accelerator Laboratory dar. In Kollaboration mit mehreren nationalen Instituten werden in einem 700 m langen Teilstueck des bereits bestehenden Tunnels 37 Kryomodule mit supraleitenden Beschleunigerkavitaeten installiert. Der Einsatz von supraleitender Beschleunigertechnologie wird eine Teilchenenergie von bis zu 4 GeV im CW (continous wave) Betrieb ermoeglichen. Zwei identische Kryoanlagen mit einer aequivalenten Leistung von je 18 kW bei 4,5 K werden im Folgenden beschrieben. Die Anlagen versorgen den Linearbeschleuniger mit Helium auf mehreren Temperaturniveaus. Superfluides Helium

In Vitro UV-Visible Spectroscopy Study of Yellow Laser Irradiation on Human Blood

Science.gov (United States)

Fuad, Siti Sakinah Mohd; Suardi, N.; Mustafa, I. S.

2018-04-01

This experimental study was performed to investigate the effect of low level yellow laser of 589nm wavelength with various laser irradiation time. Human blood samples with random diseases are irradiated with yellow laser of power density of 450mW/cm2 from 10 minutes to 60 minutes at 10 minutes intervals. The morphology of the red blood cell were also observed for different irradiation time. The result shows that there is a significant different in the absorption of light with varying laser irradiation time (p<0.01). The maximum absorption recorded at 40 minutes of irradiation at 340nm peak. Blood smear of the samples reveals that there are observable changes in the morphology of the red blood cell at 40 minutes and 60 minutes of irradiation.

Effect of helium on tensile properties of vanadium alloys

Energy Technology Data Exchange (ETDEWEB)

Chung, H.M.; Billone, M.C.; Smith, D.L. [Argonne National Lab., IL (United States)

1997-08-01

Tensile properties of V-4Cr-4Ti (Heat BL-47), 3Ti-1Si (BL-45), and V-5Ti (BL-46) alloys after irradiation in a conventional irradiation experiment and in the Dynamic Helium Charging Experiment (DHCE) were reported previously. This paper presents revised tensile properties of these alloys, with a focus on the effects of dynamically generated helium of ductility and work-hardening capability at <500{degrees}C. After conventional irradiation (negligible helium generation) at {approx}427{degrees}C, a 30-kg heat of V-4Cr-4Ti (BL-47) exhibited very low uniform elongation, manifesting a strong susceptibility to loss of work-hardening capability. In contrast, a 15-kg heat of V-3Ti-1Si (BL -45) exhibited relatively high uniform elongation ({approx}4%) during conventional irradiation at {approx}427{degrees}C, showing that the heat is resistant to loss of work-hardening capability.

Femtosecond laser irradiation of the fluorescent molecules-loaded poly(lactic-co-glycolic acid)

Science.gov (United States)

Umemoto, Taiga; Shibata, Akimichi; Terakawa, Mitsuhiro

2017-09-01

Molecular release from scaffolds is desired for tailoring cell-compatible tissue engineering. Several methods have been proposed to control molecular release, such as annealing, plasma treatment, and laser processing. In this study, we describe the alteration of Rhodamine B (RhB)-loaded poly(lactic-co-glycolic acid) (PLGA) after femtosecond laser irradiation, which was evaluated on the basis of the water absorption and mass remaining. Fluorescence measurement of released RhB molecules revealed the acceleration of the molecular release upon 400-nm laser irradiation, whereas 800-nm laser irradiation did not induce a comparable degree of change compared with non-irradiated samples. The result of the water absorption measurement indicates that the large amount of water absorption of 400-nm laser-irradiated PLGA sample may accelerate the diffusion of the loaded molecules through absorbing water, which resulted in the faster molecular release.

Current sheath curvature correlation with the neon soft x-ray emission from plasma focus device

International Nuclear Information System (INIS)

Zhang, T; Lin, X; Chandra, K A; Tan, T L; Springham, S V; Patran, A; Lee, P; Lee, S; Rawat, R S

2005-01-01

The insulator sleeve length is one of the major parameters that can severely affect the neon soft x-ray yield from a plasma focus. The effect of the insulation sleeve length on various characteristic timings of plasma focus discharges and hence the soft x-ray emission characteristics has been investigated using a resistive divider. The pinhole images and laser shadowgraphy are used to explain the observed variation in the average soft x-ray yield (measured using a diode x-ray spectrometer) with variation of the insulator sleeve length. We have found that for a neon filled plasma focus device the change in insulator sleeve length changes the current sheath curvature angle and thus the length of the focused plasma column. The optimized current sheath curvature angle is found to be between 39 0 and 41 0 , at the specific axial position of 6.2-9.3 cm from the cathode support plate, for our 3.3 kJ plasma focus device. A strong dependence of the neon soft x-ray yield on the current sheath curvature angle has thus been reported

Influence of laser shock peening on irradiation defects in austenitic stainless steels

Energy Technology Data Exchange (ETDEWEB)

Lu, Qiaofeng [Department of Mechanical & Materials Engineering, University of Nebraska–Lincoln, Lincoln, NE 68588 (United States); Su, Qing [Nebraska Center for Energy Sciences Research, University of Nebraska–Lincoln, Lincoln, NE 68588 (United States); Wang, Fei [Department of Mechanical & Materials Engineering, University of Nebraska–Lincoln, Lincoln, NE 68588 (United States); Zhang, Chenfei; Lu, Yongfeng [Department of Electrical Engineering, University of Nebraska–Lincoln, Lincoln, NE 68588 (United States); Nastasi, Michael [Department of Mechanical & Materials Engineering, University of Nebraska–Lincoln, Lincoln, NE 68588 (United States); Nebraska Center for Energy Sciences Research, University of Nebraska–Lincoln, Lincoln, NE 68588 (United States); Nebraska Center for Materials and Nanoscience, University of Nebraska-Lincoln, Lincoln, NE 68588 (United States); Cui, Bai, E-mail: bcui3@unl.edu [Department of Mechanical & Materials Engineering, University of Nebraska–Lincoln, Lincoln, NE 68588 (United States); Nebraska Center for Materials and Nanoscience, University of Nebraska-Lincoln, Lincoln, NE 68588 (United States)

2017-06-15

The laser shock peening process can generate a dislocation network, stacking faults, and deformation twins in the near surface of austenitic stainless steels by the interaction of laser-driven shock waves with metals. In-situ transmission electron microscopy (TEM) irradiation studies suggest that these dislocations and incoherent twin boundaries can serve as effective sinks for the annihilation of irradiation defects. As a result, the irradiation resistance is improved as the density of irradiation defects in laser-peened stainless steels is much lower than that in untreated steels. After heating to 300 °C, a portion of the dislocations and stacking faults are annealed out while the deformation twins remain stable, which still provides improved irradiation resistance. These findings have important implications on the role of laser shock peening on the lifetime extension of austenitic stainless steel components in nuclear reactor environments. - Highlights: •Laser shock peening generates a dislocation network, stacking faults and deformation twins in stainless steels. •Dislocations and incoherent twin boundaries serve as effective sinks for the annihilation of irradiation defects. •Incoherent twin boundaries remain as stable and effective defect sinks at 300 °C.

Bactericidal effect of Nd:YAG laser irradiation in endodontics

Science.gov (United States)

Aun, Carlos E.; Barberini, Alexandre F.; Camargo, Selma C. C.; Silva Kfouri, Luciana; Lorenzetti Simionato, Maria R.

1999-05-01

The success of endodontic therapy is based on the elimination of bacterial colonization from the endodontic system and periapical tissues. Recent studies have been showing the bactericidal effect of laser in root canal treatment. The propose of the study is to evaluate the effect of Nd:YAG laser irradiation in contaminated root canal treatment. The propose of the study is to evaluate the effect of Nd:YAG laser irradiation in contaminated root canals from upper central incisor. For the experiment 12 teeth were selected, respect at the apical third, sterilized, and 10 μm Streptococcus sanguis liquid culture were inoculated in the root canals. The laser test groups were irradiated with Nd:YAG laser at standard setting of 15Hz, 100mj and 1,5 W for 10, 20 and 30 seconds each in slow helicoidal movements from the apex to the top using a 300 micrometers fiber. After the procedure the specimens were placed in Tryptic Soy Agar, the number of colony forming units was evaluated. The experiment showed a significant reduction on viability of Streptococcus sanguis at the respective time of 20 and 30 seconds.

Technology of solid-fuel-layer targets for laser-fusion experiments

International Nuclear Information System (INIS)

Musinski, D.L.; Henderson, T.M.; Pattinson, T.R.; Tarvin, J.A.

1979-01-01

An apparatus which produces uniform solid-fuel layers in glass-shell targets for laser irradiation is described. A low-power cw laser pulse is used to vaporize the fuel within a previously frozen target which is maintained in a cold-helium environment by a cryogenic shroud. The rapid refreezing that follows the pulse forms a uniform fuel layer on the inner surface of the glass shell. This apparatus and technique meet the restrictions imposed by the experimental target chamber. The method does not perturb the target position; nor does it preclude the usual diagnostic experimets since the shroud is retracted before the main laser pulse arrives. Successful laser irradiation and implosion of solid-fuel-layer targets at KMSF have confirmed the effectiveness and reliability of this system and extended the range of laser-target-interaction studies in the cryogenic regime

NEON Citizen Science: Planning and Prototyping (Invited)

Science.gov (United States)

Gram, W.

2010-12-01

The National Ecological Observatory Network (NEON) will be a national resource for ecological research and education. NEON citizen science projects are being designed to increase awareness and educate citizen scientists about the impacts of climate change, land-use change, and invasive species on continental-scale ecological processes as well as expand NEON data collection capacity by enabling laypersons to collect geographically distributed data. The citizen science area of the NEON web portal will enable citizen scientists to collect, contribute, interpret, and visualize scientific data, as well as access training modules, collection protocols and targeted learning experiences related to citizen science project topics. For NEON, citizen science projects are a means for interested people to interact with and contribute to NEON science. Investigations at vast spatial and temporal scales often require rapid acquisition of large amounts of data from a geographically distributed population of “human sensors.” As a continental-scale ecological observatory, NEON is uniquely positioned to develop strategies to effectively integrate data collected by non-scientists into scientific databases. Ultimately, we plan to work collaboratively to transform the practice of science to include “citizens” or non-scientists in the process. Doing science is not limited to scientists, and breaking down the barriers between scientists and citizens will help people better understand the power of using science in their own decision making. In preparation for fully developing the NEON citizen science program, we are partnering with Project BudBurst (PBB), a citizen science project focused on monitoring plant phenology. The educational goals of PBB are to: (1) increase awareness of climate change, (2) educate citizen scientists about the impacts of climate change on plants and the environment, and (3) increase science literacy by engaging participants in the scientific process

Post irradiation characterization of beryllium and beryllides after high temperature irradiation up to 3000 appm helium production in HIDOBE-01

Energy Technology Data Exchange (ETDEWEB)

Fedorov, A.V., E-mail: fedorov@nrg.eu [Nuclear Research and Consultancy Group, Westerduinweg 3, Postbus 25, Petten, 1755 ZG (Netherlands); Til, S. van; Stijkel, M.P. [Nuclear Research and Consultancy Group, Westerduinweg 3, Postbus 25, Petten, 1755 ZG (Netherlands); Nakamichi, M. [Japan Atomic Energy Agency, Rokkasho (Japan); Zmitko, M. [The European Joint Undertaking for ITER and the Development of Fusion Energy, c/ Josep Pla, n° 2, Torres Diagonal Litoral, Edificio B3, Barcelona 08019 (Spain)

2016-01-15

Titanium beryllides are considered as advanced candidate material for neutron multiplier for the helium cooled pebble bed (HCPB) and/or the water cooled ceramic breeder (WCCB) breeder blankets. In the HIDOBE-01 (HIgh DOse irradiation of BEryllium) experiment, beryllium and beryllide pellets with 5 at% and 7 at% Ti are irradiated at four different target temperatures (T{sub irr}): 425 °C, 525 °C, 650 °C and 750 °C up to the dose corresponding to 3000 appm He production in beryllium. The pellets were supplied by JAEA. During post irradiation examinations the critical properties of volumetric swelling and tritium retention were studied. Both titanium beryllide grades show significantly less swelling than the beryllium grade, with the difference increasing with the irradiation temperature. The irradiation induced swelling was studied by using direct dimensions. Both beryllide grades showed much less swelling as compare to the reference beryllium grade. Densities of the grades were studied by Archimedean immersion and by He-pycnometry, giving indications of porosity formation. While both beryllide grades show no significant reduction in density at all irradiation temperatures, the beryllium density falls steeply at higher T{sub irr}. Finally, the tritium release and retention were studied by temperature programmed desorption (TPD). Beryllium shows the same strong tritium retention as earlier observed in studies on beryllium pebbles, while the tritium inventory of the beryllides is significantly less, already at the lowest T{sub irr} of 425 °C.

Optical-Thermal Response of Laser-Irradiated Tissue

CERN Document Server

Welch, Ashley J

2011-01-01

The second edition of 'Optical-Thermal Response of Laser-Irradiated Tissue' maintains the standard of excellence established in the first edition, while adjusting the content to reflect changes in tissue optics and medical applications since 1995. The material concerning light propagation now contains new chapters devoted to electromagnetic theory for coherent light. The material concerning thermal laser-tissue interactions contains a new chapter on pulse ablation of tissue. The medical applications section now includes several new chapters on Optical Coherent Tomography, acoustic imaging, molecular imaging, forensic optics and nerve stimulation. A detailed overview is provided of the optical and thermal response of tissue to laser irradiation along with diagnostic and therapeutic examples including fiber optics. Sufficient theory is included in the book so that it is suitable for a one or two semester graduate or for senior elective courses. Material covered includes: 1. light propagation and diagnostic appl...

Effect of helium preinjection and prior thermomechanical treatment on the microstructure of Type 316 SS

International Nuclear Information System (INIS)

Kohyama, A.; Ayrault, G.; Turner, A.P.L.; Igata, N.

1982-10-01

Samples of 316 SS were preinjected with 15 appM helium either hot (650 0 C) or cold (room temperature) and irradiated with 3 MeV Ni + ions to a dose level of 25 dpa at 625 0 C in order to test the validity of helium preinjection as a means of simulation of transmutant helium production. Results for preinjected and single-ion irradiated samples were compared to samples irradiated with 3 MeV Ni + and simultaneously injected with helium at a rate of 15 appM He/dpa (dual-ion irradiated samples). Preinjected samples exhibited bimodal cavity size distributions. Preinjected samples of solution annealed or solution annealed and aged material showed lower swelling than dual-ion irradiated samples. However, He preinjection in 20% cold worked samples showed greater swelling than dual-ion irradiated samples 9 figures, 1 table

Isotopic tailoring with 59Ni to study the effect of helium on microstructural evolution and mechanical properties of neutron-irradiated Fe-Cr-Ni alloys

International Nuclear Information System (INIS)

Garner, F.A.; Hamilton, M.L.; Greenwood, L.R.; Stubbins, J.F.; Oliver, B.M.

1992-03-01

Tensile testing on three model Fe-Cr-Ni alloys removed from four discharges of the 59 Ni isotopic doping experiment in FFTF-MOTA indicates that helium/dpa ratios typical of fusion reactors do not produce changes in the yield strength or elongation that are significantly different from those at much lower helium generation rates. It also appears that tensile properties approach a saturation level that is dependent only on the final irradiation temperature, but not prior temperature history or thermomechanical starting condition. The saturation in mechanical properties reflects a similar saturation in microstructure that is independent of starting condition. The successful conduct of an isotopic doping experiment was found to require post-irradiation measurement of the helium levels in order to compensate for uncertainties in the cross sections for burn-out and burn-in of 59 Ni and for uncertainties in neutron flux and spectra in the vicinity of the edge of the core

Factors affecting color strength of printing on film-coated tablets by UV laser irradiation: TiO2 particle size, crystal structure, or concentration in the film, and the irradiated UV laser power.

Science.gov (United States)

Hosokawa, Akihiro; Kato, Yoshiteru

2011-08-01

The purpose of this article is to study factors affecting color strength of printing on film-coated tablets by ultraviolet (UV) laser irradiation: particle size, crystal structure, or concentration of titanium dioxide (TiO2) in film, and irradiated UV laser power. Hydroxypropylmethylcellulose films containing 4.0% of TiO2, of which BET particle sizes were ranging from 126.1 to 219.8 nm, were irradiated 3.14W of UV laser at a wavelength 355 nm to study effects of TiO2 particle size and crystal structure on the printing. The films containing TiO2 concentration ranging from 1.0 to 7.7% were irradiated 3.14 or 5.39W of the UV laser to study effect of TiO2 concentration on the printing. The film containing 4.0% of TiO2, was irradiated the UV laser up to 6.42W to study effect of the UV laser power on the printing. The color strength of the printed films was estimated by a spectrophotometer as total color difference (dE). Particle size, crystal structure, and concentration of TiO2 in the films did not affect the printing. In the relationship between the irradiated UV laser power and dE, there found an inflection point (1.6W). When the UV laser power was below 1.6W, the films were not printed. When it was beyond the point, total color difference increased linearly in proportion with the irradiated laser power. The color strength of the printing on film was not changed by TiO2 particle size, crystal structure, and concentration, but could be controlled by regulating the irradiated UV laser power beyond the inflection point.

Multipulse nanosecond laser irradiation of silicon for the investigation of surface morphology and photoelectric properties

Science.gov (United States)

Sardar, Maryam; Chen, Jun; Ullah, Zaka; Jelani, Mohsan; Tabassum, Aasma; Cheng, Ju; Sun, Yuxiang; Lu, Jian

2017-12-01

We irradiate the single crystal boron-doped silicon (Si) with different number of laser pulses at constant fluence (7.5 J cm-2) in ambient air using Nd:YAG laser and examine its surface morphology and photoelectric properties in details. The results obtained from optical micrographs reveal the increase in heat affected zone (HAZ) and melted area of laser irradiated Si with increasing number of laser pulses. The SEM micrographs evidence the formation of various surface morphologies like laser induced periodic surface structures, crater, microcracks, clusters, cavities, pores, trapped bubbles, nucleation sites, micro-bumps, redeposited material and micro- and nano-particles on the surface of irradiated Si. The surface profilometry analysis informs that the depth of crater is increased with increase in number of incident laser pulses. The spectroscopic ellipsometry reveals that the multipulse irradiation of Si changes its optical properties (refractive index and extinction coefficient). The current-voltage (I-V) characteristic curves of laser irradiated Si show that although the multipulse laser irradiation produces considerable number of surface defects and damages, the electrical properties of Si are well sustained after the multipulse irradiation. The current findings suggest that the multipulse irradiation can be an effective way to tune the optical properties of Si for the fabrication of wide range of optoelectronic devices.

Heavy ion therapy: Bevalac epoch

International Nuclear Information System (INIS)

Castro, J.R.

1993-10-01

An overview of heavy ion therapy at the Bevelac complex (SuperHILac linear accelerator + Bevatron) is given. Treatment planning, clinical results with helium ions on the skull base and uveal melanoma, clinical results with high-LET charged particles, neon radiotherapy of prostate cancer, heavy charged particle irradiation for unfavorable soft tissue sarcoma, preliminary results in heavy charged particle irradiation of bone sarcoma, and irradiation of bile duct carcinoma with charged particles and-or photons are all covered

Ultraviolet pulsed laser irradiation of multi-walled carbon nanotubes in nitrogen atmosphere

Energy Technology Data Exchange (ETDEWEB)

Pérez del Pino, Ángel, E-mail: aperez@icmab.es; Cabana, Laura; Tobias, Gerard [Instituto de Ciencia de Materiales de Barcelona, Consejo Superior de Investigaciones Científicas (ICMAB-CSIC), Campus UAB, 08193 Bellaterra (Spain); György, Enikö [Instituto de Ciencia de Materiales de Barcelona, Consejo Superior de Investigaciones Científicas (ICMAB-CSIC), Campus UAB, 08193 Bellaterra (Spain); National Institute for Lasers, Plasma and Radiation Physics, P. O. Box MG 36, 76900 Bucharest V (Romania); Ballesteros, Belén [ICN2—Institut Catala de Nanociencia i Nanotecnologia, Campus UAB, 08193 Bellaterra, Barcelona (Spain)

2014-03-07

Laser irradiation of randomly oriented multi-walled carbon nanotube (MWCNT) networks has been carried out using a pulsed Nd:YAG UV laser in nitrogen gas environment. The evolution of the MWCNT morphology and structure as a function of laser fluence and number of accumulated laser pulses has been studied using electron microscopies and Raman spectroscopy. The observed changes are discussed and correlated with thermal simulations. The obtained results indicate that laser irradiation induces very fast, high temperature thermal cycles in MWCNTs which produce the formation of different nanocarbon forms, such as nanodiamonds. Premelting processes have been observed in localized sites by irradiation at low number of laser pulses and low fluence values. The accumulation of laser pulses and the increase in the fluence cause the full melting and amorphization of MWCNTs. The observed structural changes differ from that of conventional high temperature annealing treatments of MWCNTs.

The dynamics of Al/Pt reactive multilayer ignition via pulsed-laser irradiation

Energy Technology Data Exchange (ETDEWEB)

Murphy, Ryan D.; Reeves, Robert V.; Yarrington, Cole D.; Adams, David P. [Sandia National Laboratories, Albuquerque, New Mexico 87123 (United States)

2015-12-07

Reactive multilayers consisting of alternating layers of Al and Pt were irradiated by single laser pulses ranging from 100 μs to 100 ms in duration, resulting in the initiation of rapid, self-propagating reactions. The threshold intensities for ignition vary with the focused laser beam diameter, bilayer thickness, and pulse length and are affected by solid state reactions and conduction of heat away from the irradiated regions. High-speed photography was used to observe ignition dynamics during irradiation and elucidate the effects of heat transfer into a multilayer foil. For an increasing laser pulse length, the ignition process transitioned from a more uniform to a less uniform temperature profile within the laser-heated zone. A more uniform temperature profile is attributed to rapid heating rates and heat localization for shorter laser pulses, and a less uniform temperature profile is due to slower heating of reactants and conduction during irradiation by longer laser pulses. Finite element simulations of laser heating using measured threshold intensities indicate that micron-scale ignition of Al/Pt occurs at low temperatures, below the melting point of both reactants.

Heat transfer in pool boiling liquid neon, deuterium and hydrogen, and critical heat flux in forced convection of liquid neon

International Nuclear Information System (INIS)

Astruc, J.M.

1967-12-01

In the first part, free-convection and nucleate pool boiling heat transfer (up to burn-out heat flux) between a platinum wire of 0.15 mm in diameter in neon, deuterium and hydrogen has been studied at atmospheric pressure. These measurements were continued in liquid neon up to 23 bars (Pc ≅ 26.8 b). Film boiling heat transfer coefficients have been measured in pool boiling liquid neon at atmospheric pressure with three heating wires (diameters 0.2, 0.5, 2 mm). All the results have been compared with existing correlations. The second part is devoted to measurements of the critical heat flux limiting heat transfer with small temperature differences between the wall and the liquid neon flowing inside a tube (diameters 3 x 3.5 mm) heated by joule effect on 30 cm of length. Influences of flow stability, nature of electrical current, pressure, mass flow rate and subcooling are shown. In conclusion, the similarity of the heat transfer characteristics in pool boiling as well as in forced convection of liquid neon and hydrogen is emphasized. (author) [fr

Manipulating the mitochondria activity in human hepatic cell line Huh7 by low-power laser irradiation

Science.gov (United States)

Lynnyk, Anna; Lunova, Mariia; Jirsa, Milan; Egorova, Daria; Kulikov, Andrei; Kubinová, Šárka; Lunov, Oleg; Dejneka, Alexandr

2018-01-01

Low-power laser irradiation of red light has been recognized as a promising tool across a vast variety of biomedical applications. However, deep understanding of the molecular mechanisms behind laser-induced cellular effects remains a significant challenge. Here, we investigated mechanisms involved in the death process in human hepatic cell line Huh7 at a laser irradiation. We decoupled distinct cell death pathways targeted by laser irradiations of different powers. Our data demonstrate that high dose laser irradiation exhibited the highest levels of total reactive oxygen species production, leading to cyclophilin D-related necrosis via the mitochondrial permeability transition. On the contrary, low dose laser irradiation resulted in the nuclear accumulation of superoxide and apoptosis execution. Our findings offer a novel insight into laser-induced cellular responses, and reveal distinct cell death pathways triggered by laser irradiation. The observed link between mitochondria depolarization and triggering ROS could be a fundamental phenomenon in laser-induced cellular responses. PMID:29541521

In Vitro Evaluation of Dentin Hydraulic Conductance After 980 nm Diode Laser Irradiation.

Science.gov (United States)

Rizzante, Fabio A P; Maenosono, Rafael M; Duarte, Marco A H; Furuse, Adilson Y; Palma-Dibb, Regina G; Ishikiriama, Sérgio K

2016-03-01

Dentin hypersensitivity treatments are based on the physical obliteration of the dentinal tubules to reduce hydraulic conductance. The aim of the present study is to evaluate the hydraulic conductance of bovine root dentin after irradiation with a 980-nm diode laser, with or without associated fluoride varnish. Sixty bovine root dentin specimens were divided into six groups (n = 10 in each group): G1, G3, and G5 (0.5 W, 0.7 W, and 1 W diode laser, respectively); G2, G4, and G6 (fluoride varnish application + 0.5 W, 0.7 W, and 1 W diode laser, respectively). The dentin hydraulic conductance was evaluated at four time periods with a fluxmeter: 1) with smear layer, 2) after 37% phosphoric acid etching, 3) after the treatments, and 4) after 6% citric acid challenge. After the dentinal fluid flow measurements, specimens were also evaluated for mineral composition using energy dispersive X-ray spectroscopy (EDS). Analysis demonstrated a better result with increased irradiation power (P diode laser irradiation was associated with the application of fluoride varnish (P laser irradiation, the 1 W group was superior when compared with the 0.5 W and 0.7 W irradiated groups immediately after treatment (P laser treatments. Laser irradiation of exposed dentin promoted significant reduction in the dentin hydraulic conductance, mainly with higher energy densities and association with fluoride varnish.

Diode Laser Irradiation in Endodontic Therapy through Cycles - in vitro Study

Directory of Open Access Journals (Sweden)

Trišić Dijana

2017-07-01

Full Text Available Background/Aim: The aim of this in vitro study was to investigate the influence of irradiation cycles and resting periods, on thermal effects on the external root surface during root canal irradiation of two diode laser systems (940 nm and 975 nm, at output powers of 1 W and 2 W in continuous mode. In previous studies the rising of temperature above 7°C has been reported as biologically accepted to avoid periodontal damage on the external root surface. Material and Methods: Twenty human inferior incisors were randomly distributed into four groups, the 940 nm, and the 975 nm diode laser irradiation, both with an output power of 1 W and 2 W, in continuous mode. The thermographic camera was used to detect temperature variations on the external root surface. Digital radiography of the samples was made. Results: After three cycles of irradiation, at apical third of the root, mean temperature variation by 940 nm diode laser irradiation was 2.88°C for output power of 1 W, and 6.52°C for output power of 2 W. The 975 nm laser caused a higher temperature increase in the apical region, with temperature variation of 13.56°C by an output power of 1 W, and 30.60°C at 2 W, with a statistical significance of p ≤ 0.0001 between two laser systems compared for the same power. The resting periods of 20 s between cycles were enough to lower temperature under 7°C in the case of 1 W and 2 W for 940 nm diode laser, while for 975 nm laser, after three irradiation cycles overheating occurred at both output power rates. Conclusion: Three cycles irradiation of 940 nm diode laser, with resting periods of 20 seconds, allowed safe usage of 1 W and 2 W in CW for endodontic treatment. For 975 nm at a power rate of 1 W, the last resting period drop the temperature near the safe limit and it came under 7°C in a period less than a minute, while at the power of 2 W the resting periods were not long enough for the safe temperature decrease.

Thermal-hydraulic calculation and analysis on helium cooled ceramic breeder pebble bed assembly for in-pile irradiation and in-situ tritium extraction

International Nuclear Information System (INIS)

Guo Chunqiu; Xie Jiachun; Liu Xingmin

2013-01-01

In-pile irradiation and in-situ tritium extraction experiment is one of associated domestic research projects in ITER special program. According to the technical requirements of in-pile irradiation experiment of helium cooled ceramic breeder (ceramic) pebble bed assembly in a research reactor, the feasibility of the design for the in-pile irradiation and in-situ tritium extraction experiment of ceramic pebble bed assembly was evaluated. By conducting thermal-hydraulic design calculation with different in-pile irradiation channels, locations and structure parameters for ceramic pebble bed assembly, a reasonable design scheme of ceramic pebble bed assembly satisfying the design requirements for in-pile irradiation was obtained. (authors)

Dynamics of C2 formation in laser-produced carbon plasma in helium environment

International Nuclear Information System (INIS)

Al-Shboul, K. F.; Harilal, S. S.; Hassanein, A.; Polek, M.

2011-01-01

We investigated the role of helium ambient gas on the dynamics of C 2 species formation in laser-produced carbon plasma. The plasma was produced by focusing 1064 nm pulses from an Nd:YAG laser onto a carbon target. The emission from the C 2 species was studied using optical emission spectroscopy, and spectrally resolved and integrated fast imaging. Our results indicate that the formation of C 2 in the plasma plume is strongly affected by the pressure of the He gas. In vacuum, the C 2 emission zone was located near the target and C 2 intensity oscillations were observed both in axial and radial directions with increasing the He pressure. The oscillations in C 2 intensity at higher pressures in the expanding plume could be caused by various formation zones of carbon dimers.

Spatially resolved nanostructural transformation in graphite under femtosecond laser irradiation

International Nuclear Information System (INIS)

Marcu, A.; Avotina, L.; Porosnicu, C.; Marin, A.; Grigorescu, C.E.A.; Ursescu, D.; Lungu, M.; Demitri, N.; Lungu, C.P.

2015-01-01

Graphical abstract: - Highlights: • Polycrystalline graphite was irradiated with a high power fs (IR) laser. • Presence of a diamond peak was detected by synchrotron XRD. • XPS and Raman showed in-depth sp 3 % increase at tens of nm below the surface. • sp 3 % is increasing with laser power density but it is independent of photon absorption rate. • Graphite crystallite size locally increase at tens of nanometers below the irradiated spots. - Abstract: A polycrystalline graphite target was irradiated using infrared (800 nm) femtosecond (120 fs) laser pulses of different energies. Increase of sp 3 bonds percentage and possible diamond crystal formation were investigated ‘in-depth’ and on the irradiated surfaces. Synchrotron X-ray diffraction pattern have shown the presence of a diamond peak in one of the irradiated zones while X-ray photoelectron spectroscopy investigations have shown an increasing tendency of the sp 3 percent in the low power irradiated areas and similarly ‘in the depth’ of the higher power irradiated zones. Multiple wavelength Micro-Raman investigations have confirmed this trend along with an ‘in-depth’ (but not on the surface) increase of the crystallite size. Based on the wavelength dependent photon absorption into graphite, the observed effects are correlated with high density photon per atom and attributed to the melting and recrystallization processes taking place tens of nanometers below the target surface.

Implant Surface Temperature Changes during Er:YAG Laser Irradiation with Different Cooling Systems.

Directory of Open Access Journals (Sweden)

Abbas Monzavi

2014-04-01

Full Text Available Peri-implantitis is one of the most common reasons for implant failure. Decontamination of infected implant surfaces can be achieved effectively by laser irradiation; although the associated thermal rise may cause irreversible bone damage and lead to implant loss. Temperature increments of over 10ºC during laser application may suffice for irreversible bone damage.The purpose of this study was to evaluate the temperature increment of implant surface during Er:YAG laser irradiation with different cooling systems.Three implants were placed in a resected block of sheep mandible and irradiated with Er:YAG laser with 3 different cooling systems namely water and air spray, air spray alone and no water or air spray. Temperature changes of the implant surface were monitored during laser irradiation with a K-type thermocouple at the apical area of the fixture.In all 3 groups, the maximum temperature rise was lower than 10°C. Temperature changes were significantly different with different cooling systems used (P<0.001.Based on the results, no thermal damage was observed during implant surface decontamination by Er:YAG laser with and without refrigeration. Thus, Er:YAG laser irradiation can be a safe method for treatment of periimplantitis.

Liquid neon heat intercept for superconducting energy storage magnets

International Nuclear Information System (INIS)

Khalil, A.; McIntosh, G.E.

1982-01-01

Previous analyses of heat intercept solutions are extended to include both insulation and strut heat leaks. The impact of using storable, boiling cryogens for heat intercept fluids, specifically liquid neon and nitrogen, is also examined. The selection of fluid for the heat intercepts is described. Refrigeration power for 1000 and 5000 MWhr SMES units is shown with optimum refrigeration power for each quantity shown in tables. Nitrogen and Neon cooled intercept location for minimum total refrigeration power for a 5000 MWhr SMES are each shown, as well as the location of nitrogen and neon cooled intercepts for minimum total refrigeration power for 5000 MWhr SMES. Cost comparisons are itemized and neon cost and availability discussed. For a large energy storage magnet system, liquid neon is a more effective heat intercept fluid than liquid nitrogen. Reasons and application of the conclusion are amplified

Polycarbonate surface cell's adhesion examination after Nd:YAG laser irradiation

Energy Technology Data Exchange (ETDEWEB)

Ramazani, S.A. Ahmad, E-mail: Ramazani@sharif.ir [Polymer Group, Department of Chemical and Petroleum Engineering, Sharif University of Technology, Tehran (Iran, Islamic Republic of); Mousavi, Seyyed Abbas, E-mail: Musavi@che.sharif.ir [Department of Chemistry, Sharif University of Technology, Tehran (Iran, Islamic Republic of); Seyedjafari, Ehsan [Department of Biotechnology, University College of Science, University of Tehran (Iran, Islamic Republic of); Poursalehi, Reza [Department of Physics, University of Shahed, Tehran (Iran, Islamic Republic of); Sareh, Shohreh [Research Center of Iranian Blood Transfusion Organization, Tehran (Iran, Islamic Republic of); Silakhori, Kaveh [Laser Research Center, Atomic Energy Organization, Tehran (Iran, Islamic Republic of); Poorfatollah, Ali Akbar [Research Center of Iranian Blood Transfusion Organization, Tehran (Iran, Islamic Republic of); Shamkhali, Amir Nasser [Department of Chemistry, Sharif University of Technology, Tehran (Iran, Islamic Republic of)

2009-05-05

Nd:YAG laser treatment was used in order to increase surface cell adhesion aspects of polycarbonate (PC) films prepared via melt process. The treatment was carried out under different wavelengths and beam diameters. ATR-FTIR and UV spectra obtained from different samples before and after laser treatment in air showed that laser irradiation has induced some chemical and physical changes in surface properties. The irradiated films were also characterized using scanning electron microscopy (SEM) and contact angle measurements. Effect of pulse numbers on the surface properties was also investigated. Cell culture test was used to evaluate cell adhesion property on the PC films before and after treatment. The results obtained from this test showed that after laser treatment, the cells were attached and proliferated extensively on the Nd:YAG laser treated films in comparison with the unmodified PC. Moreover, it was revealed that a decrease in the laser beam diameter and an increase in the irradiated pulse numbers increased surface wettability and caused a better cell attachment on the polymer surface. The obtained results also showed that a decrease in the laser beam diameter and an increase in the irradiated pulse numbers increased surface wettability and caused a better cell attachment on the polymer surface.

Inhibition of Escherichia coli respiratory enzymes by short visible femtosecond laser irradiation

International Nuclear Information System (INIS)

Lu, Chieh-Han; Hsu, Yung-Yuan; Lin, Kung-Hsuan; Tsen, Kong-Thon; Kuan, Yung-Shu

2014-01-01

A visible femtosecond laser is shown to be capable of selectively inactivating a wide spectrum of microorganisms in a wavelength and pulse width dependent manner. However, the mechanism of how a visible femtosecond laser affects the viability of different microorganisms is still elusive. In this paper, the cellular surface properties, membrane integrity and metabolic rate of Escherichia coli (E. coli) irradiated by a visible femtosecond laser (λ = 415 nm, pulse width = 100 fs) with different exposure times were investigated. Our results showed that femtosecond laser treatment for 60 min led to cytoplasmic leakage, protein aggregation and alternation of the physical properties of the E. coli cell membrane. In comparison, a 10 min exposure of bacteria to femtosecond laser irradiation induced an immediate reduction of 75% in the glucose-dependent respiratory rate, while the cytoplasmic leakage was not detected. Results from enzymatic assays showed that oxidases and dehydrogenases involved in the E. coli respiratory chain exhibited divergent susceptibility after laser irradiation. This early commencement of respiratory inhibition after a short irradiation is presumed to have a dominant effect on the early stage of bacteria inactivation. (paper)

Changes in surface morphology of enamel after Er:YAG laser irradiation

Science.gov (United States)

Rechmann, Peter; Goldin, Dan S.; Hennig, Thomas

1998-04-01

Aim of the study was to investigate the surface and subsurface structure of enamel after irradiation with an Er:YAG laser (wavelength 2.94 micrometer, pulse duration 250 - 500 microseconds, free running, beam profile close to tophead, focus diameter 600 micrometer, focus distance 13 mm, different power settings, air-water spray 2 ml/min; KAVO Key Laser 1242, Kavo Biberach, Germany). The surface of more than 40 freshly extracted wisdom teeth were irradiated using a standardized application protocol (pulse repetition rate 4 and 6 Hz, moving speed of the irradiation table 2 mm/sec and 3 mm/sec, respectively). On each surface between 3 and 5 tracks were irradiated at different laser energies (60 - 500 mJ/pulse) while each track was irradiated between one and ten times respectively. For the scanning electron microscope investigation teeth were dried in alcohol and sputtered with gold. For light microscopic examinations following laser impact, samples were fixed in formaldehyde, dried in alcohol and embedded in acrylic resin. Investigations revealed that at subsurface level cracks can not be observed even at application of highest energies. Borders of the irradiated tracks seem to be sharp while melted areas of different sizes are observed on the bottom of the tracks depending on applied energy. Small microcracks can be seen on the surface of these melted areas.

The materials irradiation experiment for testing plasma facing materials at fusion relevant conditions

Energy Technology Data Exchange (ETDEWEB)

Garrison, L. M., E-mail: garrisonlm@ornl.gov; Egle, B. J. [Oak Ridge National Laboratory, 1 Bethel Valley Road, Oak Ridge, Tennessee 37831 (United States); Fusion Technology Institute, University of Wisconsin-Madison, 1500 Engineering Drive, Madison, Wisconsin 53706 (United States); Zenobia, S. J.; Kulcinski, G. L.; Santarius, J. F. [Fusion Technology Institute, University of Wisconsin-Madison, 1500 Engineering Drive, Madison, Wisconsin 53706 (United States)

2016-08-15

The Materials Irradiation Experiment (MITE-E) was constructed at the University of Wisconsin-Madison Inertial Electrostatic Confinement Laboratory to test materials for potential use as plasma-facing materials (PFMs) in fusion reactors. PFMs in fusion reactors will be bombarded with x-rays, neutrons, and ions of hydrogen and helium. More needs to be understood about the interactions between the plasma and the materials to validate their use for fusion reactors. The MITE-E simulates some of the fusion reactor conditions by holding samples at temperatures up to 1000 °C while irradiating them with helium or deuterium ions with energies from 10 to 150 keV. The ion gun can irradiate the samples with ion currents of 20 μA–500 μA; the typical current used is 72 μA, which is an average flux of 9 × 10{sup 14} ions/(cm{sup 2} s). The ion gun uses electrostatic lenses to extract and shape the ion beam. A variable power (1-20 W), steady-state, Nd:YAG laser provides additional heating to maintain a constant sample temperature during irradiations. The ion beam current reaching the sample is directly measured and monitored in real-time during irradiations. The ion beam profile has been investigated using a copper sample sputtering experiment. The MITE-E has successfully been used to irradiate polycrystalline and single crystal tungsten samples with helium ions and will continue to be a source of important data for plasma interactions with materials.

The effect of ArF laser irradiation (193 nm) on the photodegradation and etching properties of alpha-irradiated CR-39 detectors

Energy Technology Data Exchange (ETDEWEB)

Shakeri Jooybari, B. [Department of Energy Engineering and Physics, Amirkabir University of Technology, P.O. Box 15875-4413, Tehran, Islamic Republic of Iran (Iran, Islamic Republic of); Nuclear Science and Technology Research Institute (NSRT), Tehran, Islamic Republic of Iran (Iran, Islamic Republic of); Ghergherehchi, M. [College of Information and Technology/ school of Electronic and Electrical Engineering, Sungkyunkwan University, Suwon (Korea, Republic of); Afarideh, H., E-mail: hafarideh@aut.ac.ir [Department of Energy Engineering and Physics, Amirkabir University of Technology, P.O. Box 15875-4413, Tehran, Islamic Republic of Iran (Iran, Islamic Republic of); Lamehi-Rachti, M. [Nuclear Science and Technology Research Institute (NSRT), Tehran, Islamic Republic of Iran (Iran, Islamic Republic of)

2015-01-01

The effects of ArF laser irradiation (λ=193nm) at various fluences (energy dose or energy density) on the etching properties of pre-exposed (laser + alpha) CR-39 detectors were studied. First, UV–Vis and Fourier transform infrared (FTIR) spectra were acquired for non-laser-irradiated and laser-irradiated samples to detect the influence of the ArF laser on the chemical modification of the CR-39. Changes observed in the spectra indicated that the predominant process that occurred upon ArF laser irradiation was a bond-scission process. Thereafter, the mean track and bulk etching parameters were experimentally measured in ArF-laser-irradiated CR-39 detectors exposed to an alpha source ({sup 241}Am, E = 5.49 MeV). Inhomogeneous regions in the laser-irradiated side of the CR-39 demonstrated a variable etching rate on only the front side of the CR-39 detector. New equations are also presented for the average bulk etching rate for these inhomogeneous regions (front side). The mean bulk and track etching rates and the mean track dimensions increased in a fluence range of 0–37.03 mJ/cm{sup 2} because of photodegradation and the scission of chemical bonds, which are the predominant processes in this range. When the fluence was increased from 37.03 to 123.45 mJ/cm{sup 2}, the bulk and track etching rates and the track dimensions slowly decreased because of the formation of cross-linked structures on the CR-39 surface. The behavior of the bulk and track etching rates and the track dimensions appears to be proportional to the dose absorbed on the detector surface. It was observed that as the etching time was increased, the bulk and track etching rates and the track dimensions of the laser-irradiated samples decreased because of the shallow penetration depth of the 193 nm laser and the reduction in the oxygen penetration depth.

Simple Ultra-Low-Cost Undergraduate Holography Using a Modified Michelson Interferometer.

Science.gov (United States)

Rudmin, J. W.; And Others

1980-01-01

A technique is presented for producing holograms using equipment which is already in the possesion of the majority of college physics departments, which includes a slightly modified Michelson interferometer, a helium-neon laser, and a long focal-length lens. Production of high quality holograms has been achieved by inexperienced undergraduates…

Radiation damage in gallium-stabilized δ-plutonium with helium bubbles

Energy Technology Data Exchange (ETDEWEB)

Wu, FengChao [CAS Key Laboratory of Mechanical Behavior and Design of Materials, Department of Modern Mechanics, University of Science and Technology of China, Hefei, Anhui 230027 (China); Wang, Pei [Laboratory of Computational Physics, Institute of Applied Physics and Computational Mathematics, Beijing 100094 (China); Liu, XiaoYi [CAS Key Laboratory of Mechanical Behavior and Design of Materials, Department of Modern Mechanics, University of Science and Technology of China, Hefei, Anhui 230027 (China); Wu, HengAn, E-mail: wuha@ustc.edu.cn [CAS Key Laboratory of Mechanical Behavior and Design of Materials, Department of Modern Mechanics, University of Science and Technology of China, Hefei, Anhui 230027 (China)

2017-02-15

To understand the role of helium on self-irradiation effects in δ-plutonium, microstructure evolutions due to α-decay events near pre-existing helium bubbles in gallium-stabilized δ-plutonium are investigated using molecular dynamics simulations. Bubble promoting effect plays a dominating role in point defects production, resulting in increasing number of point defects. When lightweight helium atoms act as media, energy transfer discrepancy and altered spatial morphology of point defects induced by mass effect are revealed. The evolution of stacking faults surrounding the disordered core is studied and their binding effect on the propagation of point defects are presented. The cascade-induced bubble coalescence, resolution and re-nucleation driven by internal pressure are obtained in the investigation on helium behaviors. The intrinsic tendency in our simulated self-irradiation with helium bubbles is significant for understanding the underlying mechanism of aging in plutonium and its alloys.

Possibilities of UV laser oscillation on aluminium ion lines

NARCIS (Netherlands)

Grozeva, M.; Mihailova, D.B.; Sabotinov, N.

2006-01-01

An analysis of the general energy level structure of the singly ionised Al is made. It is found that in the UV spectrum of Al II there are many intensive lines starting from levels which can be populated selectively via charge transfer collisions with either helium or neon ions. The emission

Apraclonidine effects on ocular responses to YAG laser irradiation to the rabbit iris

International Nuclear Information System (INIS)

Sugiyama, K.; Kitazawa, Y.; Kawai, K.

1990-01-01

Apraclonidine (p-aminoclonidine) ophthalmic solution effectively reduces the rise in intraocular pressure (IOP) following anterior segment laser surgery. We tested the effect of topical 0.5% apraclonidine on intraocular pressure and on protein and prostaglandin (PG) E2 concentrations in aqueous humor following Q-switched Nd:YAG laser irradiation to the iris of albino rabbits, at an energy level of 2 to 200 mJ. IOP was measured prior to and for 24 hr after irradiation. Aqueous humor was withdrawn before and 1 hr after laser irradiation for determining protein (Lowry method) and PGE2 (radioimmunoassay). Four to seven rabbits were used for each experiment. The increase in IOP and protein concentration following laser irradiation was demonstrated to be dependent on the amount of laser energy. Apraclonidine completely abolished the IOP rise, and significantly reduced the elevation of protein content. Apraclonidine failed to affect the increase in PGE2

Effects of displacement damage and helium production rates on the nucleation and growth of helium bubbles - Positron annihilation spectroscopy aspects

Science.gov (United States)

Krsjak, Vladimir; Degmova, Jarmila; Sojak, Stanislav; Slugen, Vladimir

2018-02-01

Fe-12 wt% Cr model alloy samples were implanted by 250 keV He2+ ions to three different fluencies (3 × 1017, 9 × 1017 and 1.5 × 1018 cm-2) at T steel samples [1] irradiated in the frame of a two-years irradiation program of the Swiss Spallation Neutron Source. Bi-modal defect distribution represented by two defect components in positron lifetime spectrum reveals two distinct helium bubbles growth mechanisms. While at the lower helium production rate of the spallation environment, the bubbles grow primarily by migration and coalescence, at the high production rates of helium in the implanted samples, the results indicate this growth is driven by Ostwald ripening mechanism. A competitive growth process via emission of interstitial atoms (clusters) is discussed in terms of low-temperature He implantations.

Observation of rotational revivals for iodine molecules in helium droplets using a near-adiabatic laser pulse

Science.gov (United States)

Shepperson, Benjamin; Chatterley, Adam S.; Christiansen, Lars; Søndergaard, Anders A.; Stapelfeldt, Henrik

2018-01-01

A 160-ps near-Gaussian, linearly polarized laser pulse is used to align iodine (I2) molecules embedded in helium nanodroplets. The rise time of the laser pulse is sufficiently long and smooth that the alignment, characterized by , behaves adiabatically during the pulse turnon. However, after the laser pulse has turned off stays above 0.50 and a recurrence structure occurs ˜650 ps later. Measurements on isolated (I2) molecules with identical laser pulses are used to identify, through analysis of the observed half- and full-rotational revivals, that the nonadiabatic postpulse alignment dynamics results from a mild truncation of the trailing edge of the laser pulse. This truncation establishes a well-defined starting time for coherent rotation, which leads to the revival structures observed both for isolated molecules and molecules in He droplets. In the latter case the time-dependent trace recorded here is compared to that obtained previously for a 450-fs alignment pulse. It is found that the observed revivals are very similar.

High Accuracy Vector Helium Magnetometer

Data.gov (United States)

National Aeronautics and Space Administration — The proposed HAVHM instrument is a laser-pumped helium magnetometer with both triaxial vector and omnidirectional scalar measurement capabilities in a single...

Morphological changes in skin tumors caused by pulsed laser irradiation

Energy Technology Data Exchange (ETDEWEB)

Moskalik, K G; Lipova, V A; Neyshtadt, E L

1979-01-01

Morphological changes induced by treating melanomas, basaloma and flatcell skin cancers with a pulsed neodymium laser at 1060 nm, pulse length 1 msec and energy 250 to 500 J/cm/sup 2/, were studied using impressions and scrapings from the affected area. Nuclear pyknosis, nuclear and cellular elongation, vacuolization, frequent complete loss of cytoplasm, particulaly in the zone of direct irradiation, and loss of cellular structure were seen. These dystrophic changes increased with closeness to the zone of direct irradiation, culminating in necrosis. Formed and decomposed blood elements and melanin accumulated in the intracellular spaces, due to disruption of capillaries and small arteries and veins. Fewer and more aggregated melanoblasts were found after melanoma irradiation. Nuclear chromatin fusion, cytoplasmic changes and altered cell shape were observed. Basaloma cells were clustered and elongated after irradiation, with many fibrous structures and loss of cellular elements. Cytoplasmic vacuolization and lysis, bare nuclei, karyolysis, karyorrhexis and karyopyknosis were seen in corneous flat-cell cancer. In the few cases in which malignant cells were found under the scab from the first treatment the procedure was repeated. The morphological changes induced by pulsed laser irradiation are very similar to electrocoagulation necrosis, but are more localized. The ability of low and middle energy lasers to induce thrombosis and coagulation in vascular walls reduced the probability of hematogenic tumor cell dissemination. Cytological examination is highly effective in determining the degree of radical skin cancer healing due to laser treatment. 12 references, 2 figures.

Application of Laser Irradiation for Restorative Treatments

OpenAIRE

Davoudi, Amin; Sanei, Maryam; Badrian, Hamid

2016-01-01

Nowadays, lasers are widely used in many fields of medicine. Also, they can be applied at many branches of dental practice such as diagnosis, preventive procedures, restorative treatments, and endodontic therapies. Procedures like caries removal, re-mineralization, and vital pulp therapy are the most noticeable effects of laser irradiation which has gained much attention among clinicians. With controlled and appropriate wavelength, they can help stimulating dentinogenesis, controlling pulpal ...

The problem of helium in structural materials for fusion reactor

International Nuclear Information System (INIS)

Nikiforov, A.S.; Zakharov, A.P.; Chuev, V.I.

1982-01-01

The processes of helium buildup in some metals and alloys at different energy neutron flux irradiation under thermonuclear reactor conditions are considered. The data on high temperature helium embrittlement of a number of stainless steels, titanium and aluminium alloys etc. are given A review of experiments concerning the implanted helium behaviour is presented. Possible reactions between helium atoms and point defects or their clusters are discussed. Analysed are material structure variations upon buildup in them up to 1 at % of helium

Bond strength of an adhesive system irradiated with Nd:YAG laser in dentin treated with Er:YAG laser

International Nuclear Information System (INIS)

Malta, D A M P; De Andrade, M F; Costa, M M; Lizarelli, R F Z; Pelino, J E P

2008-01-01

The purpose of this in vitro study was to verify through micro tensile bond test the bond strength of an adhesive system irradiated with Nd:YAG laser in dentine previously treated with Er:YAG laser. Twenty caries free extracted human third molars were used. The teeth were divided in four experimental groups (n = 5): (G1) control group; (G2) irradiation of the adhesive system with the Nd:YAG laser; (G3) dentin treatment with Er:YAG laser; (G4) dentin treatment with Er:YAG laser followed by the irradiation of the adhesive system with Nd:YAG laser. The Er:YAG laser fluency parameter for the dentin treatment was of 60 J/cm 2 . The adhesive system was irradiated with the Nd:YAG laser with fluency of 100 J/cm 2 . Dental restorations were performed with Adper Single Bond 2/Z250. One tooth from each group was prepared for the evaluation of the adhesive interface under SEM and bond failure tests were also performed and evaluated. The statistical analysis showed statistical significant difference between the groups G1 and G3, G1 and G4, G2 and G3, and G2 and G4; and similarity between the groups G1 and G2, and G3 and G4. The adhesive failures were predominant in all the experimental groups. The SEM analysis showed an adhesive interface with features confirming the results of the mechanical tests. The Nd:YAG laser on the adhesive system did not influence the bond strength in dentin treated or not with the Er:YAG laser

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)

Spatially resolved nanostructural transformation in graphite under femtosecond laser irradiation

Energy Technology Data Exchange (ETDEWEB)

Marcu, A., E-mail: aurelian.marcu@inflpr.ro [National Institute for Laser, Plasma and Radiation Physics, 077125 Bucharest (Romania); Avotina, L. [Institute of Chemical Physics, University of Latvia, Kronvalda 4, LV 1010 Riga (Latvia); Porosnicu, C. [National Institute for Laser, Plasma and Radiation Physics, 077125 Bucharest (Romania); Marin, A. [Ilie Murgulescu” Institute of Physical Chemistry, 202 Splaiul Independentei 060021, Bucharest (Romania); Grigorescu, C.E.A. [National Institute R& D for Optoelectronics INOE 2000, 077125 Bucharest (Romania); Ursescu, D. [National Institute for Laser, Plasma and Radiation Physics, 077125 Bucharest (Romania); Lungu, M. [National Institute of Materials Physics Atomistilor Str., 105 bis, 077125, Magurele (Romania); Demitri, N. [Hard X-ray Beamline and Structural Biology, Elettra-Sincrotrone Trieste, Strada Statale 14 - km 163,5 in AREA Science Park, 34149 Basovizza TS Italy (Italy); Lungu, C.P. [National Institute for Laser, Plasma and Radiation Physics, 077125 Bucharest (Romania)

2015-11-15

Graphical abstract: - Highlights: • Polycrystalline graphite was irradiated with a high power fs (IR) laser. • Presence of a diamond peak was detected by synchrotron XRD. • XPS and Raman showed in-depth sp{sup 3}% increase at tens of nm below the surface. • sp{sup 3}% is increasing with laser power density but it is independent of photon absorption rate. • Graphite crystallite size locally increase at tens of nanometers below the irradiated spots. - Abstract: A polycrystalline graphite target was irradiated using infrared (800 nm) femtosecond (120 fs) laser pulses of different energies. Increase of sp{sup 3} bonds percentage and possible diamond crystal formation were investigated ‘in-depth’ and on the irradiated surfaces. Synchrotron X-ray diffraction pattern have shown the presence of a diamond peak in one of the irradiated zones while X-ray photoelectron spectroscopy investigations have shown an increasing tendency of the sp{sup 3} percent in the low power irradiated areas and similarly ‘in the depth’ of the higher power irradiated zones. Multiple wavelength Micro-Raman investigations have confirmed this trend along with an ‘in-depth’ (but not on the surface) increase of the crystallite size. Based on the wavelength dependent photon absorption into graphite, the observed effects are correlated with high density photon per atom and attributed to the melting and recrystallization processes taking place tens of nanometers below the target surface.

Effect of helium on void formation in nickel

International Nuclear Information System (INIS)

Brimhall, J.L.; Simonen, E.P.

1977-01-01

This study examines the influence of helium on void formation in self-ion irradiated nickel. Helium was injected either simultaneously with, or prior to, the self-ion bombardment. The void microstructure was characterized as a function of helium deposition rate and the total heavy-ion dose. In particular, at 575 0 C and 5 X 10 -3 displacements per atom per second the void density is found to be proportional to the helium deposition rate. The dose dependence of swelling is initially dominated by helium driven nucleation. The void density rapidly saturates after which swelling continues with increasing dose only from void growth. It is concluded that helium promotes void nucleation in nickel with either helium implantation technique, pre-injection or simultaneous injection. Qualitative differences, however, are recognized. (Auth.)

SEM analysis of enamel surface treated by Er:YAG laser: influence of irradiation distance.

Science.gov (United States)

Souza-Gabriel, A E; Chinelatti, M A; Borsatto, M C; Pécora, J D; Palma-Dibb, R G; Corona, S A M

2008-07-01

Depending on the distance of laser tip to dental surface a specific morphological pattern should be expected. However, there have been limited reports that correlate the Er:YAG irradiation distance with dental morphology. To assess the influence of Er:YAG laser irradiation distance on enamel morphology, by means of scanning electron microscopy (SEM). Sixty human third molars were employed to obtain discs (approximately =1 mm thick) that were randomly assigned to six groups (n=10). Five groups received Er:YAG laser irradiation (80 mJ/2 Hz) for 20 s, according to the irradiation distance: 11, 12, 14, 16, or 17 mm and the control group was treated with 37% phosphoric acid for 15 s. The laser-irradiated discs were bisected. One hemi-disc was separated for superficial analysis without subsequent acid etching, and the other one, received the phosphoric acid for 15 s. Samples were prepared for SEM. Laser irradiation at 11 and 12 mm provided an evident ablation of enamel, with evident fissures and some fused areas. At 14, 16 and 17 mm the superficial topography was flatter than in the other distances. The subsequent acid etching on the lased-surface partially removed the disorganized tissue. Er:YAG laser in defocused mode promoted slight morphological alterations and seems more suitable for enamel conditioning than focused irradiation. The application of phosphoric acid on lased-enamel surface, regardless of the irradiation distance, decreased the superficial irregularities.

Neon soft x-ray emission studies from the UNU-ICTP plasma focus operated with longer than optimal anode length

International Nuclear Information System (INIS)

Mohammadi, M A; Verma, R; Sobhanian, S; Wong, C S; Lee, S; Springham, S V; Tan, T L; Lee, P; Rawat, R S

2007-01-01

The UNU-ICTP plasma focus with a significantly longer than conventional anode can still be a reasonably good neon soft x-ray (SXR) source. The highest average neon SXR yield of 3.3 J was achieved at 3 mbar. The time difference between the two first peaks of the voltage probe signal at the radial collapse phase was found to be inversely related to the SXR yield, i.e. the smaller the time difference, the higher the yield and vice versa. The estimation of average current sheath speeds using the shadowgraphic method coupled with laser and focus peak timing signals showed that the average axial rundown speed is similar to the one obtained for the optimal anode length but the average radial compression speed is decreased significantly. The range of pressure for a good neon SXR yield, however, has become much narrower, making efficient plasma focus operation a very sensitive function of the filling gas pressure for longer than the optimal anode length

Recent progress of laser spectroscopy experiments on antiprotonic helium

Science.gov (United States)

Hori, Masaki

2018-03-01

The Atomic Spectroscopy and Collisions Using Slow Antiprotons (ASACUSA) collaboration is currently carrying out laser spectroscopy experiments on antiprotonic helium ? atoms at CERN's Antiproton Decelerator facility. Two-photon spectroscopic techniques have been employed to reduce the Doppler width of the measured ? resonance lines, and determine the atomic transition frequencies to a fractional precision of 2.3-5 parts in 109. More recently, single-photon spectroscopy of buffer-gas cooled ? has reached a similar precision. By comparing the results with three-body quantum electrodynamics calculations, the antiproton-to-electron mass ratio was determined as ?, which agrees with the known proton-to-electron mass ratio with a precision of 8×10-10. The high-quality antiproton beam provided by the future Extra Low Energy Antiproton Ring (ELENA) facility should enable further improvements in the experimental precision. This article is part of the Theo Murphy meeting issue `Antiproton physics in the ELENA era'.

ASA's Chandra Neon Discovery Solves Solar Paradox

Science.gov (United States)

2005-07-01

NASA's Chandra X-ray Observatory survey of nearby sun-like stars suggests there is nearly three times more neon in the sun and local universe than previously believed. If true, this would solve a critical problem with understanding how the sun works. "We use the sun to test how well we understand stars and, to some extent, the rest of the universe," said Jeremy Drake of the Harvard-Smithsonian Center for Astrophysics in Cambridge, Mass. "But in order to understand the sun, we need to know exactly what it is made of," he added. It is not well known how much neon the sun contains. This is critical information for creating theoretical models of the sun. Neon atoms, along with carbon, oxygen and nitrogen, play an important role in how quickly energy flows from nuclear reactions in the sun's core to its edge, where it then radiates into space. Chandra X-ray Spectrum of II Pegasi Chandra X-ray Spectrum of II Pegasi The rate of this energy flow determines the location and size of a crucial stellar region called the convection zone. The zone extends from near the sun's surface inward approximately 125,000 miles. The zone is where the gas undergoes a rolling, convective motion much like the unstable air in a thunderstorm. "This turbulent gas has an extremely important job, because nearly all of the energy emitted at the surface of the sun is transported there by convection," Drake said. The accepted amount of neon in the sun has led to a paradox. The predicted location and size of the solar convection zone disagree with those deduced from solar oscillations. Solar oscillations is a technique astronomers previously relied on to probe the sun's interior. Several scientists have noted the problem could be fixed if the abundance of neon is in fact about three times larger than currently accepted. Attempts to measure the precise amount of neon in the Sun have been frustrated by a quirk of nature; neon atoms in the Sun give off no signatures in visible light. However, in a gas

High resolution laser beam induced current images under trichromatic laser radiation: approximation to the solar irradiation.

Science.gov (United States)

Navas, F J; Alcántara, R; Fernández-Lorenzo, C; Martín-Calleja, J

2010-03-01

A laser beam induced current (LBIC) map of a photoactive surface is a very useful tool when it is necessary to study the spatial variability of properties such as photoconverter efficiency or factors connected with the recombination of carriers. Obtaining high spatial resolution LBIC maps involves irradiating the photoactive surface with a photonic beam with Gaussian power distribution and with a low dispersion coefficient. Laser emission fulfils these characteristics, but against it is the fact that it is highly monochromatic and therefore has a spectral distribution different to solar emissions. This work presents an instrumental system and procedure to obtain high spatial resolution LBIC maps in conditions approximating solar irradiation. The methodology developed consists of a trichromatic irradiation system based on three sources of laser excitation with emission in the red, green, and blue zones of the electromagnetic spectrum. The relative irradiation powers are determined by either solar spectrum distribution or Planck's emission formula which provides information approximate to the behavior of the system if it were under solar irradiation. In turn, an algorithm and a procedure have been developed to be able to form images based on the scans performed by the three lasers, providing information about the photoconverter efficiency of photovoltaic devices under the irradiation conditions used. This system has been checked with three photosensitive devices based on three different technologies: a commercial silicon photodiode, a commercial photoresistor, and a dye-sensitized solar cell. These devices make it possible to check how the superficial quantum efficiency has areas dependent upon the excitation wavelength while it has been possible to measure global incident photon-to-current efficiency values approximating those that would be obtained under irradiation conditions with sunlight.

Effect of low-level laser irradiation on osteoblast-like cells cultured on porous hydroxyapatite scaffolds

Directory of Open Access Journals (Sweden)

Serena Incerti Parenti

2013-09-01

Full Text Available OBJECTIVE: To determine the effect of laser irradiation at a low dose on human osteoblastlike cells. Materials and methods: 32 porous hydroxyapatite scaffolds currently used for bone tissue engineering were seeded with MG63 cells and irradiated or not with a GaAlAs diode laser (wavelength 915 nm, dose 2 J/cm² using different power density and exposure duration. RESULTS: After 72-h incubation, cells showed well spread morphology and good adhesion on both laser-treated and untreated scaffolds. Laser irradiation did not interfere in cell viability and proliferation as compared with the non-irradiated controls. CONCLUSION: This study suggests that there is no effect of 915 nm laser irradiation at a dose of 2 J/cm² on the proliferation rate of MG63 cells. Future investigations are needed to compare different dose and wavelength regimens in order to determine the optimal set of laser parameters for maximum cell yield and safe clinical application.

First results of laser welding of neutron irradiated stainless steel

International Nuclear Information System (INIS)

Osch, E.V. van; Hulst, D.S. d'; Laan, J.G. van der.

1994-10-01

First results of experimental investigations on the laser reweldability of neutron irradiated material are reported. These experiments include the manufacture of 'heterogeneous' joints, which means joining of irradiated stainless steel of type AISI 316L-SPH to 'fresh' unirradiated material. The newly developed laser welding facility in the ECN Hot Cell Laboratory and experimental procedures are described. Visual inspections of welded joints are reported as well as results of electron microscopy and preliminary metallographic examinations. (orig.)

Helium mobility in advanced nuclear ceramics

International Nuclear Information System (INIS)

Agarwal, Shradha

2014-01-01

The main goal of this work is to improve our knowledge on the mechanisms able to drive the helium behaviour in transition metal carbides and nitrides submitted to thermal annealing or ion irradiation. TiC, TiN and ZrC polycrystals were implanted with 3 MeV 3 He ions at room temperature in the fluence range 2 * 10 15 et 6 * 10 16 cm -2 . Some of them have been pre-irradiated with self-ions (14 MeV Ti or Zr). Fully controlled thermal annealing tests were subsequently carried out in the temperature range 1000 - 1600 C for two hours. The evolution of the helium depth distribution in function of implantation dose, temperature and pre-irradiation dose was measured thanks to the deuteron-induced nuclear reaction 3 He(d, p 0 ) 4 He between 900 keV and 1.8 MeV. The microstructure of implanted and annealed samples was investigated by transmission electron microscopy on thin foils prepared using the FIB technique. Additional characterization tools, as X-ray diffraction and Raman microspectrometry, have been also applied in order to obtain complementary information. Among the most relevant results obtained, the following have to be outlined: - double-peak helium depth profile was measured on as implanted sample for the three compounds. The first peak is located near the end of range and includes the major part of helium, a second peak located close to the surface corresponds to the helium atoms trapped by the native vacancies; - the helium retention capacity in transition metal carbides and nitrides submitted to fully controlled thermal treatments varies according to ZrC 0.92 ≤ TiC 0.96 ≤ TiN 0.96 ; - whatever the investigated material, a self-ion-induced pre-damaging does not modify the initial helium profile extent. The influence of the post-implantation thermal treatment remains preponderant in any case; - the apparent diffusion coefficient of helium is in the range 4 * 10 -18 - 2 * 10 -17 m 2 s -1 in TiC0.96 and 3.5 * 10 -19 - 5.3 * 10 -18 m 2 s -1 in TiN 0.96 between

Using laser irradiation for the surgical treatment of periodontal disease

Science.gov (United States)

Vieru, Rozana D.; Lefter, Agafita; Herman, Sonia

2002-10-01

In the marginal pr ogressive profound periodontities, we associated low level laser therapy (LLLT) to the classical surgical treatment with implant of biovitroceramics. From a total of 50 patients, 37 where irradiated with the laser. We used a diode laser, =830 nm, energy density up to 2 J cm2, in Nogier pulsed mode. The laser treatment is used in a complex of therapeutic procedures: odontal, local anti-inflammatory -- as well as in the cabinet and at home --, prosthetic, and for the morphologic and functional rebalancing. The immediate effects where: an evolution without bleeding and without post-surgical complications, as can appear at the patients who didn't benefit of laser irradiation (hematom, pain, functional alteration in the first post-surgical week). Operated tissue is recovering faster. The percentage of recurrences decreases and the success depends less on the biological potential and the immunity of each individual.

Dopant-induced ignition of helium nanoplasmas—a mechanistic study

Science.gov (United States)

Heidenreich, Andreas; Schomas, Dominik; Mudrich, Marcel

2017-12-01

Helium (He) nanodroplets irradiated by intense near-infrared laser pulses form a nanoplasma by avalanche-like electron impact ionizations (EIIs) even at lower laser intensities where He is not directly field ionized, provided that the droplets contain a few dopant atoms which provide seed electrons for the EII avalanche. In this theoretical paper on calcium and xenon doped He droplets we elucidate the mechanism which induces ionization avalanches, termed ignition. We find that the partial loss of seed electrons from the activated droplets starkly assists ignition, as the Coulomb barrier for ionization of helium is lowered by the electric field of the dopant cations, and this deshielding of the cation charges enhances their electric field. In addition, the dopant ions assist the acceleration of the seed electrons (slingshot effect) by the laser field, supporting EIIs of He and also causing electron loss by catapulting electrons away. The dopants’ ability to lower the Coulomb barriers at He as well as the slingshot effect decrease with the spatial expansion of the dopant, causing a dependence of the dopants’ ignition capability on the dopant mass. Here, we develop criteria (impact count functions) to assess the ignition capability of dopants, based on (i) the spatial overlap of the seed electron cloud with the He atoms and (ii) the overlap of their kinetic energy distribution with the distribution of Coulomb barrier heights at He. The relatively long time delays between the instants of dopant ionization and ignition (incubation times) for calcium doped droplets are determined to a large extent by the time it takes to deshield the dopant ions.

Influence of helium embrittlement on post-irradiation creep rupture behaviour of austenitic and martensitic stainless steels

International Nuclear Information System (INIS)

Wassilew, C.

1982-01-01

The author has investigated the influence of helium embrittlement on the creep rupture properties of the austenitic stainless steels 1.4970 and 1.4962 and the martensitic stainless steel 1.4914 after irradiation in the BR-2 reactor in Mol, Belgium. The results show that austenitic steels react much more strongly to the embrittlement effect of the helium than do martensitic steels. The causes of the lower embrittlement tendency of the martensitic than of both austenitic stainless steels were analysed carefully. A new embrittlement model was developed on the basis of data derived from the creep rupture experiments, and reinforced by a simple metallographic investigation of the fracture zone and its immediate environment. This model pays specific attention to the role of the twin planes as the most efficient area of increased vacancy production, and takes into account the ability of the twin boundaries to transport these vacancies with reduced energy and low loss into the high-angle grain boundaries. (author)

First-principles calculations of helium and neon desorption from cavities in silicon

International Nuclear Information System (INIS)

Eddin, A Charaf; Pizzagalli, L

2012-01-01

Combining density functional theory, the nudged elastic band technique, and the ultradense fluid model, we investigated the desorption process of He and Ne in silicon. Our results show that the internal surfaces of gas-filled bubbles are not a limiting factor during desorption experiments, since the surface reconstruction opens diffusion paths easier than in the bulk. We show that the vibrational contribution to the energy of helium in the bulk has to be considered in order to determine realistic pressures in the bubbles, when comparing experiments and simulations. At the maximum of desorption, an average pressure of 1-2 GPa is computed. (paper)

Physics of short-wavelength-laser design

Energy Technology Data Exchange (ETDEWEB)

Hagelstein, P.L.

1981-01-01

The physics and design of vuv and soft x-ray lasers pumped by ICF class high intensity infrared laser drivers are described (for example, the SHIVA laser facility at LLNL). Laser design and physics issues are discussed in the case of a photoionization pumping scheme involving Ne II and line pumping schemes involving H-like and He-like neon.

Helium trapping in aluminum and sintered aluminum powders

International Nuclear Information System (INIS)

Das, S.K.; Kaminsky, M.; Rossing, T.

1975-01-01

The surface erosion of annealed aluminum and of sintered aluminum powder (SAP) due to blistering from implantation of 100-keV 4 He + ions at room temperature has been investigated. A substantial reduction in the blistering erosion rate in SAP was observed from that in pure annealed aluminum. In order to determine whether the observed reduction in blistering is due to enhanced helium trapping or due to helium released, the implanted helium profiles in annealed aluminum and in SAP have been studied by Rutherford backscattering. The results show that more helium is trapped in SAP than in aluminum for identical irradiation conditions. The observed reduction in erosion from helium blistering in SAP is more likely due to the dispersion of trapped helium at the large Al-Al 2 O 3 interfaces and at the large grain boundaries in SAP than to helium release

Particle velocity measurements in laser irradiated foils using ORVIS

International Nuclear Information System (INIS)

Sheffield, S.A.; Fisk, G.A.

1983-01-01

Aluminum foils from 2- to 200-μm thick have been subjected to a Nd:YAG laser pulse of low irradiance (10 9 W/cm 2 , approx. 10 ns pulse) to produce laser-driven shocks in the foils. The particle velocity history of the foil side opposite the laser deposition was monitored with nanosecond resolution by a velocity interferometer system called ORVIS. These histories indicate a shock reverberation process accelerates the foil. Peak foil velocities can be adequately calculated using a ricket propulsion model developed from experiments at much higher irradiances. A velocity of 1 km/s was developed in a 2-μm-thick free foil in a time of 50 ns. Water-confined foils attained peak particle velocities about three times higher than those of free foils

Closure phenomena in pinholes irradiated by Nd laser pulses

Energy Technology Data Exchange (ETDEWEB)

Auerbach, J.M.; Holmes, N.C.; Hunt, J.T.; Linford, G.J.

1979-07-15

An experimental investigation has been made on plasma closure in pinholes irradiated by Nd glass laser pulses; 300--500-..mu..m diam pinholes of various materials and thicknesses have been irradiated by 20--100-J 300-psec FWHM pulses on the Janus laser system. Calorimetry measurements have yielded data on pinhole energy transmission and intensity loading on the periphery of the pinhole. Ultrafast streak photography measurements indicate effective closure velocities of 2--5 x 10/sup 7/ cm/sec. Scattered light measurements have shown the transmission loss through a typical spatial filter configuration to be primarily refractive in nature.

20neon ion- and x-ray-induced mammary carcinogenesis in female rats

International Nuclear Information System (INIS)

Shellabarger, C.J.; Baum, J.W.; Holtzman, S.; Stone, J.P.

1983-01-01

One of the proposed uses of heavy ion irradiation is to image lesions of the human female breast. The rat model system was chosen to assess the carcinogenic potential of heavy ion irradiation in the belief that data obtained from rat studies would have a qualitatively predictive value for the human female. Accordingly, female rats were exposed to 20 Ne ions at the BEVALAC and studied for the development of mammary neoplasia for 312 +- 2 days at Brookhaven along with rats exposed concurrently to x-irradiation or to no irradiation. As the dose of either type of radiation was increased the percent of rats with mammary adenocarcinomas, and the percent of rats with mammary fibroadenomas, tended to increase. At a prevalence of 20%, the RBE for 20 Neon ions for mammary adenocarcinomas was estimated to be larger than 5 and for mammary fibroadenomas the RBE was estimated to be less than 2. No conclusion was reached concerning whether or not the RBE might vary with dose. We suggest that 20 Ne ions do have a carcinogenic potential for rat mammary tissue and that this carcinogenic potential is likely to be greater than for x-irradiation. (DT)

Laser pulse heating of steel mixing with WC particles in a irradiated region

Science.gov (United States)

Shuja, S. Z.; Yilbas, B. S.; Ali, H.; Karatas, C.

2016-12-01

Laser pulse heating of steel mixing with tungsten carbide (WC) particles is carried out. Temperature field in the irradiated region is simulated in line with the experimental conditions. In the analysis, a laser pulse parameter is introduced, which defines the laser pulse intensity distribution at the irradiated surface. The influence of the laser parameter on the melt pool size and the maximum temperature increase in the irradiated region is examined. Surface temperature predictions are compared with the experimental data. In addition, the distribution of WC particles and their re-locations in the treated layer, due to combination of the natural convection and Marangoni currents, are predicted. The findings are compared to the experimental data. It is found that surface temperature predictions agree well with the experimental data. The dislocated WC particles form a streamlining in the near region of the melt pool wall, which agree with the experimental findings. The Gaussian distribution of the laser pulse intensity results in the maximum peak temperature and the maximum flow velocity inside the melt pool. In this case, the melt pool depth becomes the largest as compared to those corresponding to other laser pulse intensity distributions at the irradiated surface.

Muon transfer from hot muonic hydrogen atoms to neon

International Nuclear Information System (INIS)

Jacot-Guillarmod, R.; Beer, G.A.; Knowles, P.E.; Mason, G.R.; Olin, A.; Beveridge, J.L.; Marshall, G.M.; Brewer, J.H.; Forster, B.M.; Huber, T.M.; Kammel, P.; Zmeskal, J.; Petitjean, C.

1992-01-01

A negative muon beam has been directed on adjacent solid layers of hydrogen and neon. Three targets differing by their deuterium concentration were investigated. Muonic hydrogen atoms can drift to the neon layer where the muon is immediately transferred. The time structure of the muonic neon X-rays follows the exponential law with a disappearance rate corresponding to the one of μ -p atoms in each target. The rates λ ppμ and λ pd can be extracted

Kinetic analysis and modeling of daptomycin batch fermentation by Streptomyces roseosporus.

Science.gov (United States)

Lu, Wenyu; Fan, Jinghua; Wen, Jianping; Xia, Zhendong; Caiyin, Qinggele

2011-02-01

In this study, Streptomyces roseosporus was subjected to helium-neon (He-Ne) laser (632.8 nm) irradiation to improve the production ability of extracellular antibiotic daptomycin. Under the optimum irradiation dosage of 18 mW for 22 min, a stable positive mutant strain S. roseosporus LC-54 was obtained. The maximum A21978C (daptomycin is a semisynthetic antimicrobial substance derived from the A21978C complex) yield of this mutant strain was 296 mg/l, which was 146% higher than that of the wild strain. The mutant strain grew more quickly and utilized carbohydrate sources more efficiently than the wild strain. The batch culture kinetics was investigated in a 7 l bioreactor. The logistic equation for growth, the Luedeking-Piret equation for daptomycin production, and Luedeking-Piret-like equations for carbon substrate consumption were established. This model appeared to provide a reasonable description for each parameter during the growth phase and fitted fairly well with the experiment data.

Helium production cross section Measurement of Pb and Sn for 14.9 MeV neutrons

Energy Technology Data Exchange (ETDEWEB)

Takao, Yoshiyuki; Fujimoto, Toshihiro; Ozaki, Shuji; Muramasu, Masatomo; Nakashima, Hideki [Kyushu Univ., Fukuoka (Japan); Kanda, Yukinori; Ikeda, Yujiro

1998-03-01

Helium production cross sections of lead and tin for 14.9 MeV neutrons were measured by helium accumulation method. Lead and tin samples were irradiated with FNS, an intense d-T neutron source of JAERI. The amount of helium produced in the samples by the neutron irradiation was measured with the Helium Atoms Measurement System (HAMS) at Kyushu University. As the samples contained a small amount of helium because of their small helium production cross sections at 14.9 MeV, the samples were evaporated by radiation from a tungsten filament to decrease background gases at helium measurement. Uncertainties of the present results were less than {+-}4.4%. The results were compared with other experimental data in the literature and also compared with the evaluated values in JENDL-3.2. (author)

Influence of laser irradiation on deposition characteristics of cold sprayed Stellite-6 coatings

Science.gov (United States)

Li, Bo; Jin, Yan; Yao, Jianhua; Li, Zhihong; Zhang, Qunli; Zhang, Xin

2018-03-01

Depositing hard materials such as Stellite-6 solely by cold spray (CS) is challengeable due to limited ability of plastic deformation. In this study, the deposition of Stellite-6 powder was achieved by supersonic laser deposition (SLD) which combines CS with synchronous laser irradiation. The surface morphology, deposition efficiency, track shape of Stellite-6 coatings produced over a range of laser irradiation temperatures were examined so as to reveal the effects of varying laser energy inputting on the deposition process of high strength material. The microstructure, phase composition and wear/corrosion resistant properties of the as-deposited Stellite-6 coatings were also investigated. The experimental results demonstrate that the surface flatness and deposition efficiency increase with laser irradiation temperature due to the softening effect induced by laser heating. The as-deposited Stellite-6 tracks show asymmetric shapes which are influenced by the relative configuration of powder stream and laser beam. The SLD coatings can preserve the original microstructure and phase of the feedstock material due to relatively low laser energy inputting, which result in the superior wear/corrosion resistant properties as compared to the counterpart prepared by laser cladding.

Experiments on resonantly photo-pumped x-ray lasers

International Nuclear Information System (INIS)

Nilsen, J.; Porter, J.L.; Da Silva, L.B.; MacGowan, B.; Beiersdorfer, P..; Elliott, S.R.; Young, B.K.

1992-01-01

We describe our recent effort to identify and study a promising resonantly photopumped x-ray laser scheme. In particular we will describe a scheme which uses the strong emission lines of a nickel-like ion to resonantly photo-pump a neon-like ion and enhance the lasing of the neon-like 3p → 3s transitions

Effect of laser and/or electron beam irradiation on void swelling in SUS316L austenitic stainless steel

Energy Technology Data Exchange (ETDEWEB)

Yang, Subing [School of Metallurgical and Ecological Engineering, University of Science and Technology Beijing, Beijing 100083 (China); Yang, Zhanbing, E-mail: yangzhanbing@ustb.edu.cn [School of Metallurgical and Ecological Engineering, University of Science and Technology Beijing, Beijing 100083 (China); State Key Laboratory of Advanced Metallurgy, University of Science and Technology Beijing, Beijing 100083 (China); Wang, Hui [School of Metallurgical and Ecological Engineering, University of Science and Technology Beijing, Beijing 100083 (China); Watanabe, Seiichi; Shibayama, Tamaki [Center for Advanced Research of Energy and Materials, Faculty of Engineering, Hokkaido University, Sapporo, Hokkaido 060-8628 (Japan)

2017-05-15

Large amounts of void swelling still limit the application of austenitic stainless steels in nuclear reactors due to radiation-induced lattice point defects. In this study, laser and/or beam irradiation was conducted in a temperature range of 573–773 K to explore the suppression of void swelling. The results show that during sequential laser-electron beam irradiation, the void nucleation is enhanced because of the vacancy clusters and void nuclei formed under pre-laser irradiation, causing greater void swelling than single electron beam irradiation. However, simultaneous laser-electron dual-beam irradiation exhibits an obvious suppression effect on void swelling due to the enhanced recombination between interstitials and vacancies in the temperature range of 573–773 K; especially at 723 K, the swelling under simultaneous dual-beam irradiation is 0.031% which is only 22% of the swelling under electron beam irradiation (0.137%). These results provide new insight into the suppression of void swelling during irradiation. - Highlights: •The temperature dependence of void swelling under simultaneous laser-electron dual-beam irradiation has been investigated. •Pre-laser irradiation enhances void nucleation at temperatures from 573 K to 773 K. •Simultaneous laser-electron dual-beam irradiation suppresses void swelling in the temperature range of 573–773 K.

A reassessment of the effects of helium on Charpy impact properties of ferritic/martensitic steels