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Sample records for mhz hollow cathode

  1. Photoluminescence from PP-HMDSO thin films deposited using a remote plasma of 13.56 MHz hollow cathode discharge

    International Nuclear Information System (INIS)

    Naddaf, M; Saloum, S; Hamadeh, H

    2007-01-01

    Room temperature photoluminescence (PL) from plasma-polymerized hexamethyldisiloxane (PP-HMDSO) thin films deposited on silicon wafers has been investigated as a function of both the applied RF power and the monomer flow rate. Films were deposited in a low pressure-low temperature remote plasma ignited in a 13.56 MHz hollow cathode discharge reactor, using pure HMDSO as a monomer and Ar as a feed gas. The substrate temperature during the deposition was as low as 40 deg. C and the total pressure was about 0.03 mbar. Optical emission spectroscopy (OES) has been used as in situ tool for monitoring the different chemical species present in the plasma during deposition processes. The deposited PP-HMDSO films showed a strong, broad 'green/yellow' PL band. The RF power and the flow rate of the HMDSO monomer are found to have a significant impact on the PL intensity of the deposited film. The changes in the chemical bonding of the film as a function of deposition parameters have been investigated by using the Fourier transform infrared (FTIR) spectroscopic analysis and are related to PL and OES results. The 'green/yellow' PL band is ascribed to chemical groups and bonds of silicon, hydrogen and/or oxygen constituting the films, in particular, SiH, SiO bonds and silanol Si-O-H groups

  2. Photoluminescence from PP-HMDSO thin films deposited using a remote plasma of 13.56 MHz hollow cathode discharge

    Science.gov (United States)

    Naddaf, M.; Saloum, S.; Hamadeh, H.

    2007-07-01

    Room temperature photoluminescence (PL) from plasma-polymerized hexamethyldisiloxane (PP-HMDSO) thin films deposited on silicon wafers has been investigated as a function of both the applied RF power and the monomer flow rate. Films were deposited in a low pressure-low temperature remote plasma ignited in a 13.56 MHz hollow cathode discharge reactor, using pure HMDSO as a monomer and Ar as a feed gas. The substrate temperature during the deposition was as low as 40 °C and the total pressure was about 0.03 mbar. Optical emission spectroscopy (OES) has been used as in situ tool for monitoring the different chemical species present in the plasma during deposition processes. The deposited PP-HMDSO films showed a strong, broad 'green/yellow' PL band. The RF power and the flow rate of the HMDSO monomer are found to have a significant impact on the PL intensity of the deposited film. The changes in the chemical bonding of the film as a function of deposition parameters have been investigated by using the Fourier transform infrared (FTIR) spectroscopic analysis and are related to PL and OES results. The 'green/yellow' PL band is ascribed to chemical groups and bonds of silicon, hydrogen and/or oxygen constituting the films, in particular, SiH, SiO bonds and silanol Si-O-H groups.

  3. Photoluminescence from PP-HMDSO thin films deposited using a remote plasma of 13.56 MHz hollow cathode discharge

    Energy Technology Data Exchange (ETDEWEB)

    Naddaf, M; Saloum, S; Hamadeh, H [Department of Physics, Atomic Energy Commission of Syria (AECS), PO Box 6091, Damascus (Syrian Arab Republic)

    2007-07-07

    Room temperature photoluminescence (PL) from plasma-polymerized hexamethyldisiloxane (PP-HMDSO) thin films deposited on silicon wafers has been investigated as a function of both the applied RF power and the monomer flow rate. Films were deposited in a low pressure-low temperature remote plasma ignited in a 13.56 MHz hollow cathode discharge reactor, using pure HMDSO as a monomer and Ar as a feed gas. The substrate temperature during the deposition was as low as 40 deg. C and the total pressure was about 0.03 mbar. Optical emission spectroscopy (OES) has been used as in situ tool for monitoring the different chemical species present in the plasma during deposition processes. The deposited PP-HMDSO films showed a strong, broad 'green/yellow' PL band. The RF power and the flow rate of the HMDSO monomer are found to have a significant impact on the PL intensity of the deposited film. The changes in the chemical bonding of the film as a function of deposition parameters have been investigated by using the Fourier transform infrared (FTIR) spectroscopic analysis and are related to PL and OES results. The 'green/yellow' PL band is ascribed to chemical groups and bonds of silicon, hydrogen and/or oxygen constituting the films, in particular, SiH, SiO bonds and silanol Si-O-H groups.

  4. Photoluminescence from PP-HMDSO thin films deposited using a remote plasma of 13.56 MHz hollow cathode discharge

    International Nuclear Information System (INIS)

    Naddaf, M.; Saloum, S.; Hamadeh, H.

    2008-01-01

    Room temperature photoluminescence (PL) from plasma-polymerized hexamethyldisiloxane (PP-HMDSO) thin films deposited on silicon wafers has been investigated as a function of both the applied RF power and the monomer flow rate. Films were deposited in a low pressure-low temperature remote plasma ignited in a 13.56 MHz hollow cathode discharge reactor, using pure HMDSO as a monomer and Ar as a feed gas. The substrate temperature during the deposition was as low as 40 deg. C and the total pressure was about 0.03 mbar. Optical emission spectroscopy (OES) has been used as in situ tool for monitoring the different chemical species present in the plasma during deposition processes. The deposited PP-HMDSO films showed a strong, broad 'green/yellow' PL band. The RF power and the flow rate of the HMDSO monomer are found to have a significant impact on the PL intensity of the deposited film. The changes in the chemical bonding of the film as a function of deposition parameters have been investigated by using the Fourier transform infrared (FTIR) spectroscopic analysis and are related to PL and OES results. The 'green/yellow' PL band is ascribed to chemical groups and bonds of silicon, hydrogen and/or oxygen constituting the films, in particular, SiH, SiO bonds and silanol Si-O-H groups. (Authors)

  5. Plasma generation using the hollow cathod

    International Nuclear Information System (INIS)

    Moon, K.J.

    1983-01-01

    A hollow cathode of tungsten was adapted to an University of California, Berkely, LBL bucket ion source to investigate ion density fluctuations at the extractior grid. Fluctuations in plasma ion density are observed to range between 100kHz to 2 MHz. The observed fluctuation frequencies of plasma ion density are found to be inversely proportional to the square root of ion masses. It is guessed that the plasma fluctuation are also correlated with the hollow cathode length. (Author)

  6. Hollow cathode for positive ion sources

    International Nuclear Information System (INIS)

    Schechter, D.E.; Kim, J.; Tsai, C.C.

    1979-01-01

    Development to incorporate hollow cathodes into high power ion sources for neutral beam injection systems is being pursued. Hollow tube LaB 6 -type cathodes, similar to a UCLA design, have been constructed and tested in several ORNL ion source configurations. Results of testing include arc discharge parameters of >1000 and 500 amps for 0.5 and 10 second pulse lengths, respectively. Details of cathode construction and additional performance results are discussed

  7. Diagnostics of N2 Ar plasma mixture excited in a 13.56 MHz hollow cathode discharge system: application to remote plasma treatment of polyamide surface

    Science.gov (United States)

    Saloum, S.; Naddaf, M.; Alkhaled, B.

    2008-02-01

    N2-x% Ar plasma gas mixture, generated in a hollow cathode RF discharge system, has been characterized by both optical emission spectroscopy (OES) and double Langmuir probe, as a function of experimental parameters: total pressure (5-33 Pa), and different fractions of argon (7 <= x <= 80), at a constant applied RF power of 300 W. N2 dissociation degree has been investigated qualitatively by both the actinometry method and the ratio I_N/I_{N_2} of the atomic nitrogen line emission intensity at 672.3 nm to the vibrational band (0-0) of the N2 second positive system at 337.1 nm. Both methods showed that the increase in argon fraction enhances the dissociation of N2, with a maximum at x = 50 for the pressure of 5 Pa, although the two methods give two opposite trends as a function of total pressure. Spectroscopic measurements showed that the vibrational temperature of the N2 second positive system increases with both argon fraction and total pressure increase, it lies between 4900 and 12 300 K. Langmuir probe measurements showed that, in the remote zone, the electron temperature falls in the range 1.57-1.75 eV, the N_{2}^{+} density varies between 5 × 109 and 1.4 × 1010 cm-3 and that both the plasma ionization degree and electron temperature increase towards the source. In addition, the process of plasma-polyamide (PA) surface interaction, in the remote plasma zone, has been studied through OES analysis during plasma treatment of PA to monitor the possible emissions due to the polymer etching. An increase in atomic nitrogen line (672.3 nm) intensity is obtained, atomic carbon line (833.52 nm) and the band emission (0-0) from the CN (B 2Σ+-X 2Σ+) violet system were observed. The PA surface modification has been confirmed through the improvement of its hydrophilic character as the water contact angle measured after the plasma treatment significantly decreased.

  8. Diagnostics of N2-Ar plasma mixture excited in A 13.56 MHz hollow cathode discharge system: Application to remote plasma treatment of polyamide surface

    International Nuclear Information System (INIS)

    Saloum, S.; Naddaf, M.; Al-khaled, B.

    2009-01-01

    N 2 -x % Ar plasma gas mixture, generated in a hollow cathode RF discharge system, has been characterized by both optical emission spectroscopy (OES) and double langmuir probe, as a function of experimental parameters: Total pressure (5-33 Pa), and different fractions of argon (7≤ x ≤ 80), at a constant applied RF power of 300 W. N 2 dissociation degree has been investigated qualitatively by both actinometry method and the ratio of the atomic nitrogen line emission intensity at 672.3 nm to the vibrational band (0-0) of the N 2 second positive system at 337.1 nm. Both methods showed that the increase of argon fraction enhances the dissociation of N 2 , with a maximum at x=50 for the pressure of 5 Pa, although the two methods give two opposite trends as a function of total pressure. Spectroscopic measurements showed that the vibrational temperature of N 2 second positive system increases with both argon fraction and total pressure increase, it lies between 4900 K and 12300 K. Langmuir probe measurements showed that, in the remote zone, the electron temperature falls in the range 1.57-1.75 eV, the N 2 + density varies between 5.10 9 cm-3 and 1.4 10 10 cm -3 , and that both the plasma ionization degree and electron temperature increase towards the source. In addition, the process of plasma-polyamide surface interaction, in the remote plasma zone, has been studied through optical emission spectroscopy analysis during plasma treatment of polyamide to monitor the possible emissions due to the polymer etching. An increase of atomic nitrogen line (672.3 nm) intensity is obtained, atomic carbon line (833.52 nm) and the band emission (0-0) from CN (B 2 Σ + -X 2 Σ + ) violet system were observed. The polyamide surface modification has been confirmed through the improvement of its hydrophilic character as the water contact angle measured after the plasma treatment significantly decreased. (author)

  9. Diagnostics of N2-Ar plasma mixture excited in a 13.56 MHz hollow cathode discharge system: application to remote plasma treatment of polyamide surface

    International Nuclear Information System (INIS)

    Saloum, S; Naddaf, M; Alkhaled, B

    2008-01-01

    N 2 -x% Ar plasma gas mixture, generated in a hollow cathode RF discharge system, has been characterized by both optical emission spectroscopy (OES) and double Langmuir probe, as a function of experimental parameters: total pressure (5-33 Pa), and different fractions of argon (7 ≤ x ≤ 80), at a constant applied RF power of 300 W. N 2 dissociation degree has been investigated qualitatively by both the actinometry method and the ratio I N /I N 2 of the atomic nitrogen line emission intensity at 672.3 nm to the vibrational band (0-0) of the N 2 second positive system at 337.1 nm. Both methods showed that the increase in argon fraction enhances the dissociation of N 2 , with a maximum at x = 50 for the pressure of 5 Pa, although the two methods give two opposite trends as a function of total pressure. Spectroscopic measurements showed that the vibrational temperature of the N 2 second positive system increases with both argon fraction and total pressure increase, it lies between 4900 and 12 300 K. Langmuir probe measurements showed that, in the remote zone, the electron temperature falls in the range 1.57-1.75 eV, the N 2 + density varies between 5 x 10 9 and 1.4 x 10 10 cm -3 and that both the plasma ionization degree and electron temperature increase towards the source. In addition, the process of plasma-polyamide (PA) surface interaction, in the remote plasma zone, has been studied through OES analysis during plasma treatment of PA to monitor the possible emissions due to the polymer etching. An increase in atomic nitrogen line (672.3 nm) intensity is obtained, atomic carbon line (833.52 nm) and the band emission (0-0) from the CN (B 2 Σ + -X 2 Σ + ) violet system were observed. The PA surface modification has been confirmed through the improvement of its hydrophilic character as the water contact angle measured after the plasma treatment significantly decreased

  10. Diagnostics of N{sub 2}-Ar plasma mixture excited in a 13.56 MHz hollow cathode discharge system: application to remote plasma treatment of polyamide surface

    Energy Technology Data Exchange (ETDEWEB)

    Saloum, S; Naddaf, M; Alkhaled, B [Atomic Energy Commission of Syria (AECS), Physics Department, PO Box 6091, Damascus (Syrian Arab Republic)], E-mail: scientific@aec.org.sy

    2008-02-21

    N{sub 2}-x% Ar plasma gas mixture, generated in a hollow cathode RF discharge system, has been characterized by both optical emission spectroscopy (OES) and double Langmuir probe, as a function of experimental parameters: total pressure (5-33 Pa), and different fractions of argon (7 {<=} x {<=} 80), at a constant applied RF power of 300 W. N{sub 2} dissociation degree has been investigated qualitatively by both the actinometry method and the ratio I{sub N}/I{sub N{sub 2}} of the atomic nitrogen line emission intensity at 672.3 nm to the vibrational band (0-0) of the N{sub 2} second positive system at 337.1 nm. Both methods showed that the increase in argon fraction enhances the dissociation of N{sub 2}, with a maximum at x = 50 for the pressure of 5 Pa, although the two methods give two opposite trends as a function of total pressure. Spectroscopic measurements showed that the vibrational temperature of the N{sub 2} second positive system increases with both argon fraction and total pressure increase, it lies between 4900 and 12 300 K. Langmuir probe measurements showed that, in the remote zone, the electron temperature falls in the range 1.57-1.75 eV, the N{sub 2}{sup +} density varies between 5 x 10{sup 9} and 1.4 x 10{sup 10} cm{sup -3} and that both the plasma ionization degree and electron temperature increase towards the source. In addition, the process of plasma-polyamide (PA) surface interaction, in the remote plasma zone, has been studied through OES analysis during plasma treatment of PA to monitor the possible emissions due to the polymer etching. An increase in atomic nitrogen line (672.3 nm) intensity is obtained, atomic carbon line (833.52 nm) and the band emission (0-0) from the CN (B {sup 2}{sigma}{sup +}-X {sup 2}{sigma}{sup +}) violet system were observed. The PA surface modification has been confirmed through the improvement of its hydrophilic character as the water contact angle measured after the plasma treatment significantly decreased.

  11. Modeling High Pressure Micro Hollow Cathode Discharges

    National Research Council Canada - National Science Library

    Boeuf, Jean-Pierre; Pitchford, Leanne

    2004-01-01

    This report results from a contract tasking CPAT as follows: The Grantee will perform theoretical modeling of point, surface, and volume high-pressure plasmas created using Micro Hollow Cathode Discharge sources...

  12. Studies on pulsed hollow cathode capillary discharges

    Energy Technology Data Exchange (ETDEWEB)

    Choi, P; Dumitrescu-Zoita, C; Larour, J; Rous, J [Ecole Polytechnique, 91 - Palaiseau (France). Lab. de Physique des Milieux Ionises; Favre, M; Moreno, J; Chuaqui, H; Wyndham, E [Pontificia Univ. Catolica de Chile, Santiago (Chile). Facultad de Fisica; Zambra, M [Comision Chilena de Energia Nuclear, Santiago (Chile); Wong, C S [Univ. of Malaya, Kuala Lumpur (Malaysia). Plasma Research Lab

    1997-12-31

    Preliminary results on radiation characteristics of pulsed hollow cathode capillary discharges are presented. The device combines the on axis electron beam assisted ionization capabilities of the transient hollow cathode discharge with a novel high voltage low inductance geometrical design, which integrates the local energy storage into the electrode system. A nanosecond regime high temperature plasma is produced in a long, high aspect ratio capillary, with light emission in the UV to XUV region. The discharge is operated from near vacuum to pressure in the 1000 mTorr range. (author). 2 figs., 7 refs.

  13. Comparison of hollow cathode discharge plasma configurations

    International Nuclear Information System (INIS)

    Farnell, Casey C; Farnell, Cody C; Williams, John D

    2011-01-01

    Hollow cathodes used in plasma contactor and electric propulsion devices provide electrons for sustaining plasma discharges and enabling plasma bridge neutralization. Life tests show erosion on hollow cathodes exposed to the plasma environment produced in the region downstream of these devices. To explain the observed erosion, plasma flow field measurements are presented for hollow cathode generated plasmas using both directly immersed probes and remotely located plasma diagnostics. Measurements on two cathode discharge configurations are presented: (1) an open, no magnetic field configuration and (2) a setup simulating the discharge chamber environment of an ion thruster. In the open cathode configuration, large amplitude plasma potential oscillations, ranging from 20 to 85 V within a 34 V discharge, were observed using a fast response emissive probe. These oscillations were observed over a dc potential profile that included a well-defined potential hill structure. A remotely located electrostatic analyzer (ESA) was used to measure the energy of ions produced within the plasma, and energies were detected that met, and in some cases exceeded, the peak oscillatory plasma potentials detected by the emissive probe. In the ion thruster discharge chamber configuration, plasma potentials from the emissive probe again agreed with ion energies recorded by the remotely located ESA; however, much lower ion energies were detected compared with the open configuration. A simplified ion-transit model that uses temporal and spatial plasma property measurements is presented and used to predict far-field plasma streaming properties. Comparisons between the model and remote measurements are presented.

  14. Numerical simulation of the sustaining discharge in radio frequency hollow cathode discharge in argon

    Energy Technology Data Exchange (ETDEWEB)

    Jiang, Xin-Xian; He, Feng, E-mail: hefeng@bit.edu.cn; Ouyang, Ji-Ting [School of Physics, Beijing Institute of Technology, Beijing 100081 (China); Chen, Qiang, E-mail: lppmchenqiang@hotmail.com; Ge, Teng [Laboratory of Plasma Physics and Materials, Beijing Institute of Graphic Communication, Beijing 10081 (China)

    2014-03-15

    In this paper, a two-dimensional fluid model was developed to study the radio frequency (RF) hollow cathode discharge (HCD) in argon at 1 Torr. The evolutions of the particle density distribution and the ionization rate distribution in RF HCD at 13.56 MHz indicate that the discharge mainly occurs inside the hollow cathode. The spatio-temporal distributions of the ionization rate and the power deposition within the hollow cathode imply that sheath oscillation heating is the primary mechanism to sustain the RF HCD, whereas secondary electron emission plays a negligible role. However, as driving frequency decreases, secondary electron heating becomes a dominant mechanism to sustain the discharge in RF hollow cathode.

  15. Improved Rare-Earth Emitter Hollow Cathode

    Science.gov (United States)

    Goebel, Dan M.

    2011-01-01

    An improvement has been made to the design of the hollow cathode geometry that was created for the rare-earth electron emitter described in Compact Rare Earth Emitter Hollow Cathode (NPO-44923), NASA Tech Briefs, Vol. 34, No. 3 (March 2010), p. 52. The original interior assembly was made entirely of graphite in order to be compatible with the LaB6 material, which cannot be touched by metals during operation due to boron diffusion causing embrittlement issues in high-temperature refractory materials. Also, the graphite tube was difficult to machine and was subject to vibration-induced fracturing. This innovation replaces the graphite tube with one made out of refractory metal that is relatively easy to manufacture. The cathode support tube is made of molybdenum or molybdenum-rhenium. This material is easily gun-bored to near the tolerances required, and finish machined with steps at each end that capture the orifice plate and the mounting flange. This provides the manufacturability and robustness needed for flight applications, and eliminates the need for expensive e-beam welding used in prior cathodes. The LaB6 insert is protected from direct contact with the refractory metal tube by thin, graphite sleeves in a cup-arrangement around the ends of the insert. The sleeves, insert, and orifice plate are held in place by a ceramic spacer and tungsten spring inserted inside the tube. To heat the cathode, an insulating tube is slipped around the refractory metal hollow tube, which can be made of high-temperature materials like boron nitride or aluminum nitride. A screw-shaped slot, or series of slots, is machined in the outside of the ceramic tube to constrain a refractory metal wire wound inside the slot that is used as the heater. The screw slot can hold a single heater wire that is then connected to the front of the cathode tube by tack-welding to complete the electrical circuit, or it can be a double slot that takes a bifilar wound heater with both leads coming out

  16. Barium Depletion in Hollow Cathode Emitters

    Science.gov (United States)

    Polk, James E.; Capece, Angela M.; Mikellides, Ioannis G.; Katz, Ira

    2009-01-01

    The effect of tungsten erosion, transport and redeposition on the operation of dispenser hollow cathodes was investigated in detailed examinations of the discharge cathode inserts from an 8200 hour and a 30,352 hour ion engine wear test. Erosion and subsequent re-deposition of tungsten in the electron emission zone at the downstream end of the insert reduces the porosity of the tungsten matrix, preventing the ow of barium from the interior. This inhibits the interfacial reactions of the barium-calcium-aluminate impregnant with the tungsten in the pores. A numerical model of barium transport in the internal xenon discharge plasma shows that the barium required to reduce the work function in the emission zone can be supplied from upstream through the gas phase. Barium that flows out of the pores of the tungsten insert is rapidly ionized in the xenon discharge and pushed back to the emitter surface by the electric field and drag from the xenon ion flow. This barium ion flux is sufficient to maintain a barium surface coverage at the downstream end greater than 0.6, even if local barium production at that point is inhibited by tungsten deposits. The model also shows that the neutral barium pressure exceeds the equilibrium vapor pressure of the impregnant decomposition reaction over much of the insert length, so the reactions are suppressed. Only a small region upstream of the zone blocked by tungsten deposits is active and supplies the required barium. These results indicate that hollow cathode failure models based on barium depletion rates in vacuum dispenser cathodes are very conservative.

  17. Barium depletion in hollow cathode emitters

    International Nuclear Information System (INIS)

    Polk, James E.; Mikellides, Ioannis G.; Katz, Ira; Capece, Angela M.

    2016-01-01

    Dispenser hollow cathodes rely on a consumable supply of Ba released by BaO-CaO-Al 2 O 3 source material in the pores of a tungsten matrix to maintain a low work function surface. The examination of cathode emitters from long duration tests shows deposits of tungsten at the downstream end that appear to block the flow of Ba from the interior. In addition, a numerical model of Ba transport in the cathode plasma indicates that the Ba partial pressure in the insert may exceed the equilibrium vapor pressure of the dominant Ba-producing reaction, and it was postulated previously that this would suppress Ba loss in the upstream part of the emitter. New measurements of the Ba depletion depth from a cathode insert operated for 8200 h reveal that Ba loss is confined to a narrow region near the downstream end, confirming this hypothesis. The Ba transport model was modified to predict the depletion depth with time. A comparison of the calculated and measured depletion depths gives excellent qualitative agreement, and quantitative agreement was obtained assuming an insert temperature 70 °C lower than measured beginning-of-life values

  18. Plasma processes inside dispenser hollow cathodes

    International Nuclear Information System (INIS)

    Mikellides, Ioannis G.; Katz, Ira; Goebel, Dan M.; Polk, James E.; Jameson, Kristina K.

    2006-01-01

    A two-dimensional fluid model of the plasma and neutral gas inside dispenser orificed hollow cathodes has been developed to quantify plasma processes that ultimately determine the life of the porous emitters inserted in these devices. The model self-consistently accounts for electron emission from the insert as well as for electron and ion flux losses from the plasma. Two cathodes, which are distinctively different in size and operating conditions, have been simulated numerically. It is found that the larger cathode, with outer tube diameter of 1.5 cm and orifice diameter of 0.3 cm, establishes an effective emission zone that spans approximately the full length of the emitter when operated at a discharge current of 25 A and a flow rate of 5.5 sccm. The net heating of the emitter is caused by ions that are produced by ionization of the neutral gas inside the tube and are then accelerated by the sheath along the emitter. The smaller cathode, with an outer diameter of 0.635 cm and an orifice diameter of 0.1 cm, does not exhibit the same operational characteristics. At a flow rate of 4.25 sccm and discharge current of 12 A, the smaller cathode requires 4.5 times the current density near the orifice and operates with more than 6 times the neutral particle density compared to the large cathode. As a result, the plasma particle density is almost one order of magnitude higher compared to the large cathode. The plasma density in this small cathode is high enough such that the Debye length is sufficiently small to allow 'sheath funneling' into the pores of the emitter. By accessing areas deeper into the insert material, it is postulated that the overall emission of electrons is significantly enhanced. The maximum emission current density is found to be about 1 A/mm 2 in the small cathode, which is about one order of magnitude higher than attained in the large cathode. The effective emission zone in the small cathode extends to about 15% of the emitter length only, and the

  19. Compact Rare Earth Emitter Hollow Cathode

    Science.gov (United States)

    Watkins, Ronald; Goebel, Dan; Hofer, Richard

    2010-01-01

    A compact, high-current, hollow cathode utilizing a lanthanum hexaboride (LaB6) thermionic electron emitter has been developed for use with high-power Hall thrusters and ion thrusters. LaB6 cathodes are being investigated due to their long life, high current capabilities, and less stringent xenon purity and handling requirements compared to conventional barium oxide (BaO) dispenser cathodes. The new cathode features a much smaller diameter than previously developed versions that permit it to be mounted on axis of a Hall thruster ( internally mounted ), as opposed to the conventional side-mount position external to the outer magnetic circuit ("externally mounted"). The cathode has also been reconfigured to be capable of surviving vibrational loads during launch and is designed to solve the significant heater and materials compatibility problems associated with the use of this emitter material. This has been accomplished in a compact design with the capability of high-emission current (10 to 60 A). The compact, high-current design has a keeper diameter that allows the cathode to be mounted on the centerline of a 6- kW Hall thruster, inside the iron core of the inner electromagnetic coil. Although designed for electric propulsion thrusters in spacecraft station- keeping, orbit transfer, and interplanetary applications, the LaB6 cathodes are applicable to the plasma processing industry in applications such as optical coatings and semiconductor processing where reactive gases are used. Where current electrical propulsion thrusters with BaO emitters have limited life and need extremely clean propellant feed systems at a significant cost, these LaB6 cathodes can run on the crudest-grade xenon propellant available without impact. Moreover, in a laboratory environment, LaB6 cathodes reduce testing costs because they do not require extended conditioning periods under hard vacuum. Alternative rare earth emitters, such as cerium hexaboride (CeB6) can be used in this

  20. Emission mechanism in high current hollow cathode arcs

    International Nuclear Information System (INIS)

    Krishnan, M.

    1976-01-01

    Large (2 cm-diameter) hollow cathodes have been operated in a magnetoplasmadynamic (MPD) arc over wide ranges of current (0.25 to 17 kA) and mass flow (10 -3 to 8 g/sec), with orifice current densities and mass fluxes encompassing those encountered in low current steady-state hollow cathode arcs. Detailed cathode interior measurements of current and potential distributions show that maximum current penetration into the cathode is about one diameter axially upstream from the tip, with peak inner surface current attachment up to one cathode diameter upstream of the tip. The spontaneous attachment of peak current upstream of the cathode tip is suggested as a criterion for characteristic hollow cathode operation. This empirical criterion is verified by experiment

  1. Uranium vapor generator: pulsed hollow cathode lamp

    International Nuclear Information System (INIS)

    Carleer, M.; Gagne, J.; Leblanc, B.; Demers, Y.; Mongeau, B.

    1979-01-01

    The production of uranium vapors has been studied in the 5 L 0 6 ground state using a pulsed hollow cathode lamp. The evolution of the 238 U ( 5 L 0 6 ) concentration with time has been studied with Xe and Ar as buffer gases. A density of 2.7 x 10 13 atoms cm -3 was obtained with Xe as a buffer gas. In addition, those measurements, obtained from the absorption of a laser beam tuned to the 5758.143 A ( 5 L 0 6 -17,361 7 L 6 ) transition, allowed the determination of the transition probability A=2.1 x 10 5 sec -1 and of the branching ratio BR=0.08 for this transition

  2. Development of Hollow Cathode of High Power Middle Pressure Arcjet

    National Research Council Canada - National Science Library

    Vaulin, Eujeni

    1995-01-01

    ...: Determine integral performances of arcjet devices in nitrogen, ammonia, and their mixtures using hollow cathode devices at low and high current levels, perform short term tests (up to 50 hours...

  3. Ultraviolet Generation by Atmospheric Micro-Hollow Cathode Discharges

    National Research Council Canada - National Science Library

    Cooper, J

    2004-01-01

    Report developed under STTR contract for topic AFO3TOl9. This report documents the program objectives, work performed, results obtained, and future plans for a program to develop micro-hollow cathode discharge (MHCD...

  4. Study of the hollow cathode plasma electron-gun

    International Nuclear Information System (INIS)

    Zhang Yonghui; Jiang Jinsheng; Chang Anbi

    2003-01-01

    For developing a novel high-current, long pulse width electron source, the theoretics and mechanism of the hollow cathode plasma electron-gun are analyzed in detail in this paper, the structure and the physical process of hollow cathode plasma electron-gun are also studied. This gun overcomes the limitations of most high-power microwave tubes, which employ either thermionic cathodes that produce low current-density beams because of the limitation of the space charge, or field-emission cathodes that offer high current density but provide only short pulse width because of plasma closure of the accelerating gap. In the theories studying on hollow cathode plasma electron-gun, the characteristic of the hollow-cathode discharge is introduced, the action during the forming of plasma of the stimulating electrode and the modulating anode are discussed, the movement of electrons and ions and the primary parameters are analyzed, and the formulas of the electric field, beam current density and the stabilization conditions of the beam current are also presented in this paper. The numerical simulation is carried out based on Poisson's equation, and the equations of current continuity and movement. And the optimized result is reported. On this basis, we have designed a hollow-cathode-plasma electron-gun, whose output pulse current is 2 kA, and pulse width is 1 microsecond

  5. Measurements on the source properties of a hollow cathode

    NARCIS (Netherlands)

    Vogels, J.M.M.J.; Konings, L.U.E.; Koelman, J.M.V.A.; Schram, D.C.; Bötticher, W.; Wenk, H.; Schulz-Gulde, E.

    1983-01-01

    The ion production rate of a hollow cathode in a magnetized arc has been measured. At low magnetic fields supersonic ion drifts have been observed. The ionized fraction of the gas flow decreases with increasing flow and the ion flux saturates at high flow rates

  6. Space-time-dependent development of the plasma in a pulsed hollow-cathode discharge

    International Nuclear Information System (INIS)

    Schaefer, G.; Wages, M.

    1988-01-01

    This paper presents streak camera investigations on the space-time-dependent development of pulsed hollow-cathode discharges (HCD's) starting from low-current preionization discharges. The discharges started closer to the end of the cathode, then moved further into the cathode, and then spread over a longer range along the axis of the cathode. The depth range of the intense pulsed hollow-cathode plasma was found to be two to eight times the cathode diameter

  7. Optogalvanic detection of the Zeeman effect in a hollow-cathode discharge

    International Nuclear Information System (INIS)

    Langlois, E.; Gagne, J.

    1987-01-01

    Optogalvanic detection of complex Zeeman patterns in a hollow-cathode lamp is investigated. Uranium lines with J 1 = 6 and J 2 = 7 are resolved, with our best results obtained using intermodulate optogalvanic spectroscopy (but this scheme is applicable only to lines giving strong signals). This detection method has a 40-MHz resolution, so a magnetic field of 0.1 T is sufficient to resolve most patterns. Weak lines can be studied with modulated optogalvanic spectroscopy. However, the stronger field required in this case perturbs the discharge. Although they are impractical for the measurement of component relative intensities, these detection methods may find applications in the determination of Lande g factors

  8. Sputter deposition of BSCCO films from a hollow cathode

    International Nuclear Information System (INIS)

    Lanagan, M.T.; Kampwirth, R.T.; Doyle, K.; Kowalski, S.; Miller, D.; Gray, K.E.

    1991-01-01

    High-T c superconducting thin films were deposited onto MgO single crystal substrates from a hollow cathode onto ceramic targets with the nominal composition of Bi 2 Sr 2 CaCu 2 O x . Films similar in composition to those used for the targets were deposited on MgO substrates by rf sputtering. The effects of sputtering time, rf power, and post-annealing on film microstructure and properties were studied in detail. Substrate temperature was found to have a significant influence on the film characteristics. Initial results show that deposition rates from a hollow cathode are an order of magnitude higher than those of a planar magnetron source at equivalent power levels. Large deposition rates allow for the coating of long lengths of wire

  9. Molecular beam sampling of a hollow cathode arc

    International Nuclear Information System (INIS)

    Theuws, P.

    1981-01-01

    This thesis deals with the description of the process of molecular beam sampling of a Hollow Cathode Arc. The aim of the study is twofold, i.e. investigation of the applicability of molecular beam sampling as a plasma diagnostic and the use of a Hollow Cathode Arc as a high intensity beam source for ground state atoms and metastable state atoms in the superthermal energy range. Suitable models are introduced, describing the process of molecular beam sampling of both ground state atoms and metastable state atoms. Fast ground state atoms produced by ion-atom collisions. The experimental facilities, i.e. the Hollow Cathode Arc, the time-of-flight machine and the dye laser system are described. And an alternative detection scheme for ground state atoms is presented and experimental results on the molecular beam sampling of a low density plasma (densities 10 19 -10 20 m -3 ) in the long arc configuration are reported. The results on the short arc configuration (densities 10 21 -10 22 m -3 ) are discussed. (Auth.)

  10. The effect of cathode geometry on barium transport in hollow cathode plasmas

    International Nuclear Information System (INIS)

    Polk, James E.; Mikellides, Ioannis G.; Katz, Ira; Capece, Angela M.

    2014-01-01

    The effect of barium transport on the operation of dispenser hollow cathodes was investigated in numerical modeling of a cathode with two different orifice sizes. Despite large differences in cathode emitter temperature, emitted electron current density, internal xenon neutral and plasma densities, and size of the plasma-surface interaction region, the barium transport in the two geometries is qualitatively very similar. Barium is produced in the insert and flows to the surface through the porous structure. A buildup of neutral Ba pressure in the plasma over the emitter surface can suppress the reactions supplying the Ba, restricting the net production rate. Neutral Ba flows into the dense Xe plasma and has a high probability of being ionized at the periphery of this zone. The steady state neutral Ba density distribution is determined by a balance between pressure gradient forces and the drag force associated with collisions between neutral Ba and neutral Xe atoms. A small fraction of the neutral Ba is lost upstream. The majority of the neutral Ba is ionized in the high temperature Xe plasma and is pushed back to the emitter surface by the electric field. The steady state Ba + ion density distribution results from a balance between electrostatic and pressure forces, neutral Xe drag and Xe + ion drag with the dominant forces dependent on location in the discharge. These results indicate that hollow cathodes are very effective at recycling Ba within the discharge and therefore maintain a high coverage of Ba on the emitter surface, which reduces the work function and sustains high electron emission current densities at moderate temperatures. Barium recycling is more effective in the cathode with the smaller orifice because the Ba is ionized in the dense Xe plasma concentrated just upstream of the orifice and pushed back into the hollow cathode. Despite a lower emitter temperature, the large orifice cathode has a higher Ba loss rate through the orifice because the Xe

  11. Electron and ion kinetics in a micro hollow cathode discharge

    Energy Technology Data Exchange (ETDEWEB)

    Kim, G J; Iza, F; Lee, J K [Electronics and Electrical Engineering Department, Pohang University of Science and Technology, Pohang, 790-784 (Korea, Republic of)

    2006-10-21

    Electron and ion kinetics in a micro hollow cathode discharge are investigated by means of two-dimensional axisymmetric particle-in-cell Monte Carlo collision simulations. Argon discharges at 10 and 300 Torr are studied for various driving currents. Electron and ion energy probability functions (IEPF) are shown at various times and locations to study the spatio-temporal behaviour of the discharge. The electron energy probability function (EEPF) evolves from the Druyvesteyn type in the early stages of the discharge into a two (or three) temperature distribution when steady state is reached. In steady state, secondary electrons accelerated across the cathode fall populate the high energy tail of the EEPF while the low energy region is populated by trapped electrons. The IEPF evolves from a Maxwellian in the negative glow (bulk) to a two temperature distribution on the cathode surface. The overpopulation of low energy ions near the cathode surface is attributed to a larger collision cross section for low energy ions and ionization within the cathode fall.

  12. Electron and ion kinetics in a micro hollow cathode discharge

    International Nuclear Information System (INIS)

    Kim, G J; Iza, F; Lee, J K

    2006-01-01

    Electron and ion kinetics in a micro hollow cathode discharge are investigated by means of two-dimensional axisymmetric particle-in-cell Monte Carlo collision simulations. Argon discharges at 10 and 300 Torr are studied for various driving currents. Electron and ion energy probability functions (IEPF) are shown at various times and locations to study the spatio-temporal behaviour of the discharge. The electron energy probability function (EEPF) evolves from the Druyvesteyn type in the early stages of the discharge into a two (or three) temperature distribution when steady state is reached. In steady state, secondary electrons accelerated across the cathode fall populate the high energy tail of the EEPF while the low energy region is populated by trapped electrons. The IEPF evolves from a Maxwellian in the negative glow (bulk) to a two temperature distribution on the cathode surface. The overpopulation of low energy ions near the cathode surface is attributed to a larger collision cross section for low energy ions and ionization within the cathode fall

  13. Geometrical Aspects of a Hollow-cathode Magnetron (HCM)

    International Nuclear Information System (INIS)

    Cohen, Samuel A.; Wang, Zhehui

    1998-01-01

    A hollow-cathode magnetron (HCM), built by surrounding a planar sputtering-magnetron cathode with a hollow-cathode structure (HCS), is operable at substantially lower pressures than its planar-magnetron counterpart. We have studied the dependence of magnetron operational parameters on the inner diameter D and length L of a cylindrical HCS. Only when L is greater than L sub zero, a critical length, is the HCM operable in the new low-pressure regime. The critical length varies with HCS inner diameter D. Explanations of the lower operational pressure regime, critical length, and plasma shape are proposed and compared with a one-dimension diffusion model for energetic or primary electron transport. At pressures above 1 mTorr, an electron-impact ionization model with Bohm diffusion at a temperature equivalent to one-half the primary electron energy and with an ambipolar constraint can explain the ion-electron pair creation required to sustain the discharge. The critical length L sub zero is determined by the magnetization length of the primary electrons

  14. Geometrical aspects of a hollow-cathode planar magnetron

    International Nuclear Information System (INIS)

    Wang, Z.; Cohen, S.A.

    1999-01-01

    A hollow-cathode planar magnetron (HCPM), built by surrounding a planar sputtering-magnetron cathode with a hollow-cathode structure (HCS) [Z. Wang and S. A. Cohen, J. Vac. Sci. Technol. A 17, 77 (1999)], is operable at substantially lower pressures than its planar-magnetron counterpart. HCPM operational parameters depend on the inner diameter D and length L of its cylindrical HCS. Only when L is greater than L 0 , a critical length, is the HCPM operable in the new low-pressure regime. The critical length varies with HCS inner diameter D. Explanations of the lower operational pressure regime, critical length, and plasma shape are proposed and compared with a one-dimension diffusion model for energetic electron transport. At pressures above 1 mTorr, Bohm diffusion (temperature congruent primary electron energy), with an ambipolar constraint, can explain the ion - electron pair creation required to sustain the discharge. At the lowest pressure, ∼0.3 mTorr, collision-limited diffusion creates fewer ion - electron pairs than required for steady state and therefore cannot explain the experimental data. The critical length L 0 is consistent with the magnetization length of the primary electrons. copyright 1999 American Institute of Physics

  15. Theory of hollow cathode arc discharges. II. Metastable state balance inside the cathode. Application to argon

    International Nuclear Information System (INIS)

    Ferreira, C.M.; Delcroix, J.L.

    1975-01-01

    In the hollow cathode the metastable species are created by fast electrons, which are emitted by the cathode wall and injected in the plasma across a space-charge sheath, and destroyed by Maxwellian electrons. A detailed analysis of the different electronic destruction mechanisms in argon shows that the re-excitation up to 3p 5 4p states plays a very important role. Solutions of the metastable balance equation were obtained in a wide range of variation of the discharge parameters displaying the best conditions of operation to obtain high concentrations [fr

  16. Atomization of thorium in a hollow-cathode type discharge

    International Nuclear Information System (INIS)

    Pianarosa, P.; Demers, Y.; Gagne, J.M.

    1984-01-01

    The atomization of thorium metal in a hollow-cathode electrical discharge has been investigated. Laser absorption spectroscopy with the laser tuned on the 5760.55 A (0-17355 1 cm -1 ) transition of Th I was used to evaluate the density of atoms in the 3 F 2 ground state. The results obtained (densities up to 10 13 atoms cm -3 ) show that our discharge tube is a suitable source of thorium metal atoms for laser assisted spectroscopic analysis of this element. (author)

  17. Ionization processes in a transient hollow cathode discharge before electric breakdown: statistical distribution

    International Nuclear Information System (INIS)

    Zambra, M.; Favre, M.; Moreno, J.; Wyndham, E.; Chuaqui, H.; Choi, P.

    1998-01-01

    The charge formation processes in a hollow cathode region (HCR) of transient hollow cathode discharge have been studied at the final phase. The statistical distribution that describe different processes of ionization have been represented by Gaussian distributions. Nevertheless, was observed a better representation of these distributions when the pressure is near a minimum value, just before breakdown

  18. Emission characteristics of laser ablation-hollow cathode glow discharge spectral source

    Directory of Open Access Journals (Sweden)

    Karatodorov Stefan

    2014-11-01

    Full Text Available The emission characteristics of a scheme combining laser ablation as sample introduction source and hollow cathode discharge as excitation source are presented. The spatial separation of the sample material introduction by laser ablation and hollow cathode excitation is achieved by optimizing the gas pressure and the sample-cathode gap length. At these conditions the discharge current is maximized to enhance the analytical lines intensity.

  19. Neutralizer Hollow Cathode Simulations and Comparisons with Ground Test Data

    Science.gov (United States)

    Mikellides, Ioannis G.; Snyder, John S.; Goebel, Dan M.; Katz, Ira; Herman, Daniel A.

    2009-01-01

    The fidelity of electric propulsion physics-based models depends largely on the validity of their predictions over a range of operating conditions and geometries. In general, increased complexity of the physics requires more extensive comparisons with laboratory data to identify the region(s) that lie outside the validity of the model assumptions and to quantify the uncertainties within its range of application. This paper presents numerical simulations of neutralizer hollow cathodes at various operating conditions and orifice sizes. The simulations were performed using a two-dimensional axisymmetric model that solves numerically a relatively extensive system of conservation laws for the partially ionized gas in these devices. A summary of the comparisons between simulation results and Langmuir probe measurements is provided. The model has also been employed to provide insight into recent ground test observations of the neutralizer cathode in NEXT. It is found that a likely cause of the observed keeper voltage drop is cathode orifice erosion. However, due to the small magnitude of this change, is approx. 0.5 V (less than 5% of the beginning-of-life value) over 10 khrs, and in light of the large uncertainties of the cathode material sputtering yield at low ion energies, other causes cannot be excluded. Preliminary simulations to understand transition to plume mode suggest that in the range of 3-5 sccm the existing 2-D model reproduces fairly well the rise of the keeper voltage in the NEXT neutralizer as observed in the laboratory. At lower flow rates the simulation produces oscillations in the keeper current and voltage that require prohibitively small time-steps to resolve with the existing algorithms.

  20. Determination of electric field strength and kinetic temperature in the cathode fall region of a hollow cathode discharge

    Energy Technology Data Exchange (ETDEWEB)

    De la Rosa, M I; Perez, C; Gruetzmacher, K [Universidad de Valladolid, Facultad de Ciencias, 47071 Valladolid (Spain); Gonzalo, A B; Del Val, J A, E-mail: delarosa@opt.uva.e [Universidad de Salamanca, Escuela Politecnica Superior, 05003 Avila (Spain)

    2010-05-01

    In this work, we demonstrate the high potential of two-photon excitation of the 1S -2S transition of atomic hydrogen followed by optogalvanic detection, for measuring under identical experimental conditions, the kinetic temperature and the electric field strength in the cathode sheath region of a hollow cathode discharge. The first obtained results for both parameters are discussed in this paper.

  1. Hollow Cathode Studies for the Next Generation Ion Engines in JAXA

    Science.gov (United States)

    Ohkawa, Yasushi; Hayakawa, Yukio; Yoshida, Hideki; Miyazaki, Katsuhiro; Kitamura, Shoji; Kajiwara, Kenichi

    The current status of experimental studies of hollow cathodes for the next-generation ion engines in the Aerospace Research and Development Directorate, JAXA is described. One of the topics on the hollow cathode studies is a life test of a discharge cathode. The keeper disk, orifice plate, and cathode tube of this discharge cathode are made of "high density graphite," which possesses much higher tolerance to ion impingement compared with conventional metal materials. The life test had started in March 2006 and the cumulative operation time reached 15,600 hours in April 2008. No severe degradation has been found both in the operation voltages and electrodes so far, and the test is favorably in progress. In addition to the life test of the discharge cathode, some experiments for design optimization of neutralizer cathodes have been performed. A life test of the neutralizer cathode is being started in June 2008.

  2. Coronal and local thermodynamic equilibriums in a hollow cathode discharge

    International Nuclear Information System (INIS)

    Zheng Xutao

    2005-01-01

    A characteristic two-section profile of excited-state populations is observed in a hollow cathode discharge and is explained by coexistence of the coronal equilibrium (CE) and the local thermodynamic equilibrium (LTE). At helium pressure 0.1 Torr and cathode current 200-300 mA, vacuum ultraviolet radiations from He I 1snp 1 P (n=2-16) and He II np 2 P (n=2-14) are resolved with a 2.2-M McPherson spectrometer. Relative populations of these states are deduced from the discrete line intensities and are plotted against energy levels. For both the He I and He II series, as energy level increases, populations of high-n (n>10) states are found to decrease much more quickly than low-n (n<7) populations. While low-n populations are described with the CE dominated by direct electron-impact excitations, high-n populations are fitted with the LTE to calculate the population temperatures of gas atoms and ions. Validities of the CE and LTE in different n-ranges are considered on the competition between radiative decays of the excited states and their collisions with gas atoms. (author)

  3. Ultra-Compact Center-Mounted Hollow Cathodes for Hall Effect Thrusters, Phase I

    Data.gov (United States)

    National Aeronautics and Space Administration — The proposed innovation is a long lifetime, compact hollow cathode that can be mounted along the axis of a 600 W-class Hall effect thruster. Testing at kilowatt...

  4. Hollow Carbon Nanofiber-Encapsulated Sulfur Cathodes for High Specific Capacity Rechargeable Lithium Batteries

    KAUST Repository

    Zheng, Guangyuan; Yang, Yuan; Cha, Judy J.; Hong, Seung Sae; Cui, Yi

    2011-01-01

    Sulfur has a high specific capacity of 1673 mAh/g as lithium battery cathodes, but its rapid capacity fading due to polysulfides dissolution presents a significant challenge for practical applications. Here we report a hollow carbon nanofiber

  5. Investigation of chlorination of zirconium and hafnium and their compounds in discharge from hollow cathode

    International Nuclear Information System (INIS)

    Ioffe, R.B.; Korovin, Yu.I.

    1978-01-01

    The possibility is investigated of chlorinating various zirconium and hafnium compounds (metal, oxide, carbide) in a hot discharge from a hollow cathode with various chlorinating reagents: copper monochloride, nickel chloride, magnesium chloride, for the purpose of accelerating their entrance into the excitation zone. It has been shown thermodynamically and experimentally that chlorination of metal zirconium and hafnium and their carbides with copper monochloride in hot hollow cathode conditions provides a sharp increase in the intensity of the lines of these elements

  6. Ignition and extinction phenomena in helium micro hollow cathode discharges

    International Nuclear Information System (INIS)

    Kulsreshath, M. K.; Schwaederle, L.; Dufour, T.; Lefaucheux, P.; Dussart, R.; Sadeghi, N.; Overzet, L. J.

    2013-01-01

    Micro hollow cathode discharges (MHCD) were produced using 250 μm thick dielectric layer of alumina sandwiched between two nickel electrodes of 8 μm thickness. A through cavity at the center of the chip was formed by laser drilling technique. MHCD with a diameter of few hundreds of micrometers allowed us to generate direct current discharges in helium at up to atmospheric pressure. A slowly varying ramped voltage generator was used to study the ignition and the extinction periods of the microdischarges. The analysis was performed by using electrical characterisation of the V-I behaviour and the measurement of He*( 3 S 1 ) metastable atoms density by tunable diode laser spectroscopy. At the ignition of the microdischarges, 2 μs long current peak as high as 24 mA was observed, sometimes followed by low amplitude damped oscillations. At helium pressure above 400 Torr, an oscillatory behaviour of the discharge current was observed just before the extinction of the microdischarges. The same type of instability in the extinction period at high pressure also appeared on the density of He*( 3 S 1 ) metastable atoms, but delayed by a few μs relative to the current oscillations. Metastable atoms thus cannot be at the origin of the generation of the observed instabilities

  7. Ignition and extinction phenomena in helium micro hollow cathode discharges

    Energy Technology Data Exchange (ETDEWEB)

    Kulsreshath, M. K.; Schwaederle, L.; Dufour, T.; Lefaucheux, P.; Dussart, R. [GREMI, CNRS/Université d' Orléans (UMR7344), Orléans (France); Sadeghi, N. [LIPhy, CNRS and Universite Joseph Fourier (UMR5588), Grenoble (France); Overzet, L. J. [GREMI, CNRS/Université d' Orléans (UMR7344), Orléans (France); PSAL, UTDallas, Richardson, Texas 75080-3021 (United States)

    2013-12-28

    Micro hollow cathode discharges (MHCD) were produced using 250 μm thick dielectric layer of alumina sandwiched between two nickel electrodes of 8 μm thickness. A through cavity at the center of the chip was formed by laser drilling technique. MHCD with a diameter of few hundreds of micrometers allowed us to generate direct current discharges in helium at up to atmospheric pressure. A slowly varying ramped voltage generator was used to study the ignition and the extinction periods of the microdischarges. The analysis was performed by using electrical characterisation of the V-I behaviour and the measurement of He*({sup 3}S{sub 1}) metastable atoms density by tunable diode laser spectroscopy. At the ignition of the microdischarges, 2 μs long current peak as high as 24 mA was observed, sometimes followed by low amplitude damped oscillations. At helium pressure above 400 Torr, an oscillatory behaviour of the discharge current was observed just before the extinction of the microdischarges. The same type of instability in the extinction period at high pressure also appeared on the density of He*({sup 3}S{sub 1}) metastable atoms, but delayed by a few μs relative to the current oscillations. Metastable atoms thus cannot be at the origin of the generation of the observed instabilities.

  8. A flexible platform for simulations of sputtering hollow cathode discharges for laser applications

    NARCIS (Netherlands)

    Mihailova, D.B.; Grozeva, M.; Hagelaar, G.J.M.; Dijk, van J.; Brok, W.J.M.; Mullen, van der J.J.A.M.

    2008-01-01

    The Plasimo modelling platform, extended with a cathode wall sputtering module is used to study the discharge processes and to optimise the design parameters of a sputtering hollow cathode discharge (HCD). We present Plasimo simulations of a HCD used for laser applications. A time dependent

  9. Pulsed hollow cathode discharge: intense electron beam and filamentary plasma

    International Nuclear Information System (INIS)

    Modreanu, Gabriel

    1998-01-01

    This work deals with a transient hollow cathode discharge optimised by a preionization one and providing intense electron beams. It exists a preionization current value for which the pulsed discharge becomes a very straight and bright filament, well collimated on the discharge tube axis for some tenths of centimeters. A remarkable feature of this discharge is that, without internal metallic electrodes very pure plasma could be produced. Using self-biasing by the beam of a Faraday cup placed only few millimeters behind the anode, we deduced the beam electron's distribution function and its temporal behavior for two radial positions, on the axis and 1 millimeter off-axis, respectively. The real advantage of this measurement technique is the transient polarization character, which allows analysis very closely from the electron beam extraction hole. On the other side, using the emission spectroscopy, we have studied the plasma produced in electron beam - gas interaction and deduced the temporal evolution of the electron temperature. The temporal behavior of the filamentary plasma diameter shows a constriction at the last moments of the beam existence, followed by diffusion controlled expansion. The ambipolar diffusion coefficient corresponding to the estimated electron temperature describes quite well this expansion and allows a quantitative interpretation of the measured temperature diminution, with taking into account the preferential fast electrons escape. The analysis of both beam and post-beam plasma phases suggests potential applications of this robust, very reproducible and not expensive discharge also susceptible to be external monitored. The beam - target interaction could be used for PVD, elementary analysis and filamentary or point-like X-ray emission. (author) [fr

  10. Ion source using a hollow cathode discharge system and especially, particle accelerator comprising said source

    International Nuclear Information System (INIS)

    Mourier, Georges.

    1975-01-01

    An ion source provided with a hollow cathode discharge system is presented. The ion extraction system is designed in view of generating a beam directed towards a point of use located far from the point of ion production. Said source essentially comprises two cathodes facing each other, an anode at a continuous voltage with respect to the cathodes, a heated filament beyond the cathode on the path of the extracted beam, and a grid between said filament and cathode. The ion extraction is limited to a certain portion of the ions present inside the plasma, so as the discharge to continue to be sustained by itself. For that purpose pierced cathodes are used, with a transparency (the ratio of the hole area to the whole cathode area) not much higher than 50% [fr

  11. Spectroscopic measurements of plasma temperatures and electron number density in a uranium hollow cathode discharge lamp

    International Nuclear Information System (INIS)

    Shah, M.L.; Suri, B.M.; Gupta, G.P.

    2015-01-01

    The HCD (Hollow Cathode Discharge) lamps have been used as a source of free atoms of any metal, controllable by direct current in the lamp. The plasma parameters including neutral species temperature, atomic excitation temperature and electron number density in a see-through type, homemade uranium hollow cathode discharge lamp with neon as a buffer gas have been investigated using optical emission spectroscopic techniques. The neutral species temperature has been measured using the Doppler broadening of a neon atomic spectral line. The atomic excitation temperature has been measured using the Boltzmann plot method utilizing uranium atomic spectral lines. The electron number density has been determined from the Saha-Boltzmann equation utilizing uranium atomic and ionic spectral lines. To the best of our knowledge, all these three plasma parameters are simultaneously measured for the first time in a uranium hollow cathode discharge lamp

  12. Hollow Cathode Assembly Development for the HERMeS Hall Thruster

    Science.gov (United States)

    Sarver-Verhey, Timothy R.; Kamhawi, Hani; Goebel, Dan M.; Polk, James E.; Peterson, Peter Y.; Robinson, Dale A.

    2016-01-01

    To support the operation of the HERMeS 12.5 kW Hall Thruster for NASA's Asteroid Redirect Robotic Mission, hollow cathodes using emitters based on barium oxide impregnate and lanthanum hexaboride are being evaluated through wear-testing, performance characterization, plasma modeling, and review of integration requirements. This presentation will present the development approach used to assess the cathode emitter options. A 2,000-hour wear-test of development model Barium Oxide (BaO) hollow cathode is being performed as part of the development plan. Specifically this test is to identify potential impacts cathode emitter life during operation in the HERMeS thruster. The cathode was operated with a magnetic field-equipped anode that simulates the HERMeS hall thruster operating environment. Cathode discharge performance has been stable with the device accumulating 743 hours at the time of this report. Observed voltage changes are attributed to keeper surface condition changes during testing. Cathode behavior during characterization sweeps exhibited stable behavior, including cathode temperature. The details of the cathode assembly operation of the wear-test will be presented.

  13. Modulation Transfer Spectroscopy of Ytterbium Atoms in a Hollow Cathode Lamp

    International Nuclear Information System (INIS)

    Wang Wen-Li; Xu Xin-Ye

    2011-01-01

    We present the experimental study of modulation transfer spectroscopy of ytterbium atoms in a hollow cathode lamp. The dependences of its linewidth, slope and magnitude on the various experimental parameters are measured and fitted by the well-known theoretical expressions. The experimental results are in good agreement with the theoretical prediction. We have observed the Dicke narrowing effect by increasing the current of the hollow cathode lamp. It is also found that there are the optimal current and laser power to generate the better modulation transfer spectroscopy signal, which can be employed for locking the laser frequency to the atomic transition. (atomic and molecular physics)

  14. Utilization of ultraviolet radiation of cold hollow cathode discharge plasma for water disinfection

    International Nuclear Information System (INIS)

    Soloshenko, I.O.; Bazhenov, V.Yu.; Khomych, V.O.; Tsiolko, V.V.; Potapchenko, N.G.; Goncharuk, V.V.

    2006-01-01

    We study the possibility to use the ultraviolet radiation of a hollow cathode discharge plasma for water disinfection. We have performed the comparative experiments on the influence of ultraviolet radiation of the mentioned discharge plasma, as well as that of a standard low pressure mercury lamp

  15. Reduction of gas flow into a hollow cathode ion source for a neutral beam injector

    International Nuclear Information System (INIS)

    Tanaka, S.; Akiba, M.; Arakawa, Y.; Horiike, H.; Sakuraba, J.

    1982-01-01

    Experimental studies have been made on the reduction of the gas flow rate into ion sources which utilize a hollow cathode. The electron emitter of the hollow cathode was a barium oxide impregnated porous tungsten tube. The hollow cathode was mounted to a circular or a rectangular bucket source and the following results were obtained. There was a tendency for the minimum gas flow rate for the stable source operation to decrease with increasing orifice diameter of the hollow cathode up to 10 mm. A molybdenum button with an appropriate diameter set in front of the orifice reduced the minimum gas flow rate to one half of that without button. An external magnetic field applied antiparallel to the field generated by the heater current stabilized the discharges and reduced the minimum gas flow rate to one half of that without field. Combination of the button and the antiparallel field reduced the minimum gas flow rate from the initial value (9.5 Torr 1/s) to 2.4 Torr 1/s. The reason for these effects was discussed on the basis of the theory for arc starvation

  16. Plasma characteristics in the discharge region of a 20 A emission current hollow cathode

    Science.gov (United States)

    Mingming, SUN; Tianping, ZHANG; Xiaodong, WEN; Weilong, GUO; Jiayao, SONG

    2018-02-01

    Numerical calculation and fluid simulation methods were used to obtain the plasma characteristics in the discharge region of the LIPS-300 ion thruster’s 20 A emission current hollow cathode and to verify the structural design of the emitter. The results of the two methods indicated that the highest plasma density and electron temperature, which improved significantly in the orifice region, were located in the discharge region of the hollow cathode. The magnitude of plasma density was about 1021 m-3 in the emitter and orifice regions, as obtained by numerical calculations, but decreased exponentially in the plume region with the distance from the orifice exit. Meanwhile, compared to the emitter region, the electron temperature and current improved by about 36% in the orifice region. The hollow cathode performance test results were in good agreement with the numerical calculation results, which proved that that the structural design of the emitter and the orifice met the requirements of a 20 A emission current. The numerical calculation method can be used to estimate plasma characteristics in the preliminary design stage of hollow cathodes.

  17. Geometrical features in longitudinal sputtering hollow cathode discharges for laser applications

    NARCIS (Netherlands)

    Mihailova, D.B.; Dijk, van J.; Hagelaar, G.J.M.; Karatodorov, S.; Zahariev, P.; Grozeva, M.; Mullen, van der J.J.A.M.

    2012-01-01

    Longitudinal sputtering hollow cathode discharge (HCD) used as active medium for lasing is studied by means of numerical modelling. Due to the longitudinal non-uniformities of the discharge, the laser operation could be strongly affected. The non-uniformity of the discharge is mainly influenced by

  18. Development and Testing of High Current Hollow Cathodes for High Power Hall Thrusters

    Science.gov (United States)

    Kamhawi, Hani; Van Noord, Jonathan

    2012-01-01

    NASA's Office of the Chief Technologist In-Space Propulsion project is sponsoring the testing and development of high power Hall thrusters for implementation in NASA missions. As part of the project, NASA Glenn Research Center is developing and testing new high current hollow cathode assemblies that can meet and exceed the required discharge current and life-time requirements of high power Hall thrusters. This paper presents test results of three high current hollow cathode configurations. Test results indicated that two novel emitter configurations were able to attain lower peak emitter temperatures compared to state-of-the-art emitter configurations. One hollow cathode configuration attained a cathode orifice plate tip temperature of 1132 degC at a discharge current of 100 A. More specifically, test and analysis results indicated that a novel emitter configuration had minimal temperature gradient along its length. Future work will include cathode wear tests, and internal emitter temperature and plasma properties measurements along with detailed physics based modeling.

  19. Influence of the radial spacing between cathodes on the surface composition of iron samples sintered by hollow cathode electric discharge

    Directory of Open Access Journals (Sweden)

    Brunatto S.F.

    2001-01-01

    Full Text Available The present work reports an investigation of the influence of the radial spacing between cathodes on the iron sintering process by hollow cathode electrical discharge, with surface enrichment of the alloying elements Cr and Ni. Pressed cylindrical samples of 9.5 mm diameter and density of 7.0 ± 0.1 g/cm³ were prepared by compaction of Ancorsteel 1000C iron powder. These samples, constituting the central cathode, were positioned concentrically in the interior of an external cathode machined from a tube of stainless steel AISI 310 (containing: 25% Cr, 16% Ni, 1.5% Mn, 1.5% Si, 0.03% C and the remainder Fe. Sintering was done at 1150 °C, for 120 min, utilizing radial spacings between the central and hollow cathodes of 3, 6 and 9 mm and a gas mixture of 80% Ar and 20% H2, with a flow rate of 5 cm³/s at a pressure of 3 Torr. The electric discharge was generated using a pulsed voltage power source, with a period of 200 mus. The radial spacing had only a slight influence on the quantity of atoms of alloying elements deposited and diffused on the surface of the sample. Analysis with a microprobe showed the presence of chrome (up to 4.0% and nickel (up to 3.0%, in at. % at the surface of the samples. This surface enrichment can be attributed to the mechanism of sputtering of the metallic atoms present in the external cathode, with the deposition of these elements on the sample surface and consequent diffusion within the sample.

  20. A Hollow-Structured Manganese Oxide Cathode for Stable Zn-MnO₂ Batteries.

    Science.gov (United States)

    Guo, Xiaotong; Li, Jianming; Jin, Xu; Han, Yehu; Lin, Yue; Lei, Zhanwu; Wang, Shiyang; Qin, Lianjie; Jiao, Shuhong; Cao, Ruiguo

    2018-05-05

    Aqueous rechargeable zinc-manganese dioxide (Zn-MnO₂) batteries are considered as one of the most promising energy storage devices for large scale-energy storage systems due to their low cost, high safety, and environmental friendliness. However, only a few cathode materials have been demonstrated to achieve stable cycling for aqueous rechargeable Zn-MnO₂ batteries. Here, we report a new material consisting of hollow MnO₂ nanospheres, which can be used for aqueous Zn-MnO₂ batteries. The hollow MnO₂ nanospheres can achieve high specific capacity up to ~405 mAh g −1 at 0.5 C. More importantly, the hollow structure of birnessite-type MnO₂ enables long-term cycling stability for the aqueous Zn-MnO₂ batteries. The excellent performance of the hollow MnO₂ nanospheres should be due to their unique structural properties that enable the easy intercalation of zinc ions.

  1. Hollow Carbon Nanofiber-Encapsulated Sulfur Cathodes for High Specific Capacity Rechargeable Lithium Batteries

    KAUST Repository

    Zheng, Guangyuan

    2011-10-12

    Sulfur has a high specific capacity of 1673 mAh/g as lithium battery cathodes, but its rapid capacity fading due to polysulfides dissolution presents a significant challenge for practical applications. Here we report a hollow carbon nanofiber-encapsulated sulfur cathode for effective trapping of polysulfides and demonstrate experimentally high specific capacity and excellent electrochemical cycling of the cells. The hollow carbon nanofiber arrays were fabricated using anodic aluminum oxide (AAO) templates, through thermal carbonization of polystyrene. The AAO template also facilitates sulfur infusion into the hollow fibers and prevents sulfur from coating onto the exterior carbon wall. The high aspect ratio of the carbon nanofibers provides an ideal structure for trapping polysulfides, and the thin carbon wall allows rapid transport of lithium ions. The small dimension of these nanofibers provides a large surface area per unit mass for Li2S deposition during cycling and reduces pulverization of electrode materials due to volumetric expansion. A high specific capacity of about 730 mAh/g was observed at C/5 rate after 150 cycles of charge/discharge. The introduction of LiNO3 additive to the electrolyte was shown to improve the Coulombic efficiency to over 99% at C/5. The results show that the hollow carbon nanofiber-encapsulated sulfur structure could be a promising cathode design for rechargeable Li/S batteries with high specific energy. © 2011 American Chemical Society.

  2. Effects of discharge parameters on the micro-hollow cathode sustained glow discharge

    Science.gov (United States)

    Shoujie, HE; Peng, WANG; Jing, HA; Baoming, ZHANG; Zhao, ZHANG; Qing, LI

    2018-05-01

    The effects of parameters such as pressure, first anode radius, and the cavity diameter on the micro-hollow cathode sustained glow discharge are investigated by using a two-dimensional self-consistent fluid model in pure argon. The results indicate that the three parameters influence the discharge in the regions inside and outside of the cavity. Under a fixed voltage on each electrode, a larger volume of high density plasma can be produced in the region between the first and the second anodes by selecting the appropriate pressure, the higher first anode, and the appropriate cavity diameter. As the pressure increases, the electron density inside the hollow cathode, the high density plasma volume between the first anode and second anodes, and the radial electric field in the cathode cavity initially increase and subsequently decrease. As the cavity diameter increases, the high-density plasma volume between the first and second anodes initially increases and subsequently decreases; whereas the electron density inside the hollow cathode decreases. As the first anode radius increases, the electron density increases both inside and outside of the cavity. Moreover, the increase of the electron density is more obvious in the microcathode sustained region than in the micro cavity region. The results reveal that the discharge inside the cavity interacts with that outside the cavity. The strong hollow cathode effect and the high-density plasma inside the cavity favor the formation of a sustained discharge between the first anode and the second anodes. Results also show that the radial boundary conditions exert a considerably weaker influence on the discharge except for a little change in the region close to the radial boundary.

  3. Gas-discharge sources with charged particle emission from the plasma of glow discharge with a hollow cathode

    CERN Document Server

    Semenov, A P

    2001-01-01

    One studied properties of a magnetron discharge with a cold hollow and uncooled rod cathodes. One demonstrated the dominant effect of thermoelectron emission of a rod cathode heated in a discharge on characteristics of discharge and on emission properties of a gas-discharge plasma and the possibility pf a smooth transition of glow discharge to diffusion mode of arc discharge combustion. Paper describes sources of ions and electrons with improved physical and generalized design and engineering parameters. One shows the promise of the electrode structure of a hollow cathode magnetron discharge to be used as a source, in particular, of the atomic hydrogen and of atom flow of a working rod cathode

  4. Facile Synthesis of V2O5 Hollow Spheres as Advanced Cathodes for High-Performance Lithium-Ion Batteries

    Directory of Open Access Journals (Sweden)

    Xingyuan Zhang

    2017-01-01

    Full Text Available Three-dimensional V2O5 hollow structures have been prepared through a simple synthesis strategy combining solvothermal treatment and a subsequent thermal annealing. The V2O5 materials are composed of microspheres 2–3 μm in diameter and with a distinct hollow interior. The as-synthesized V2O5 hollow microspheres, when evaluated as a cathode material for lithium-ion batteries, can deliver a specific capacity as high as 273 mAh·g−1 at 0.2 C. Benefiting from the hollow structures that afford fast electrolyte transport and volume accommodation, the V2O5 cathode also exhibits a superior rate capability and excellent cycling stability. The good Li-ion storage performance demonstrates the great potential of this unique V2O5 hollow material as a high-performance cathode for lithium-ion batteries.

  5. Auxiliary glow discharge in the trigger unit of a hollow-cathode thyratron

    Energy Technology Data Exchange (ETDEWEB)

    Korolev, Yu. D.; Landl, N. V., E-mail: landl@lnp.hcei.tsc.ru; Geyman, V. G.; Frants, O. B.; Shemyakin, I. A.; Nekhoroshev, V. O. [Russian Academy of Sciences, Institute of High-Current Electronics, Siberian Branch (Russian Federation)

    2016-08-15

    Results from studies of a low-current glow discharge with a hollow cathode are presented. A specific feature of the discharge conditions was that a highly emissive tablet containing cesium carbonate was placed in the cathode cavity. In the absence of a tablet, the discharge ignition voltage was typically ≥3.5 kV, while the burning voltage was in the range of 500–600 V. The use of the tablet made it possible to decrease the ignition voltage to 280 V and maintain the discharge burning voltage at a level of about 130 V. A model of the current sustainment in a hollow-cathode discharge is proposed. Instead of the conventional secondary emission yield, the model uses a generalized emission yield that takes into account not only ion bombardment of the cathode, but also the emission current from an external source. The model is used to interpret the observed current−voltage characteristics. The results of calculations agree well with the experimental data. It is shown that, in some discharge modes, the external emission current from the cathode can reach 25% of the total discharge current.

  6. Self-induced optogalvanic effect in a segmented hollow-cathode discharge

    Science.gov (United States)

    Steflekova, V.; Zhechev, D.

    2018-03-01

    Optogalvanic (OG) interaction is simulated and studied in a segmented hollow-cathode discharge (SHCD). HCD-lamps are used to induce an OG signal by their own emission or by that of another lamp. The efficiency of the OG of a Ne/Cu HCD lamp in the range 320-380 nm is estimated theoretically. An irregular galvanic peak arising near the inflection point in the i-V curve (∂V/∂i<0) is detected. Its origin is related to Penning ionization of the sputtered cathode material.

  7. Study of the three-step photoionization of uranium using a hollow cathode discharge tube

    International Nuclear Information System (INIS)

    Hu, Q.; Yin, L.; Zhang, Y.; Jin, C.; Cui, J.; Su, H.; Lin, F.

    1986-01-01

    The hollow cathode discharge (HCD) tube as a spectral light source has been developed. Because any element including refractory metals can be atomized by the cathode sputtering effect in HCD, a simple and reliable atomic vapor source produced by HCD has been widely used in laser spectroscopy. To the authors' knowledge, there is no previous work on the photoionization processes of metal atoms using an HCD tube. Here the authors report their study of the resonant three-step ionization of U in a homemade HCD tube

  8. Nitrogen Atom Energy Distributions in a Hollow-cathode Planar Sputtering Magnetron

    International Nuclear Information System (INIS)

    Ruzic, D.N.; Goeckner, M.J.; Cohen, S.A.; Wang, Zhehui

    1999-01-01

    Energy distributions of N atoms in a hollow-cathode planar sputtering magnetron were obtained by use of optical emission spectroscopy. A characteristic line, N I 8216.3 , well-separated from molecular nitrogen emission bands, was identified. Jansson's nonlinear spectral deconvolution method, refined by minimization of χ w ampersand sup2; , was used to obtain the optimal deconvolved spectra. These showed nitrogen atom energies from 1 eV to beyond 500 eV. Based on comparisons with VFTRIM results, we propose that the energetic N atoms are generated from N 2 + ions after these ions are accelerated through the sheath and dissociatively reflect from the cathode

  9. Observation of a very high electron current extraction mode in a hollow cathode discharge

    International Nuclear Information System (INIS)

    Hershcovitch, A.

    1993-01-01

    Earlier results by Hershcovitch, Kovarik, and Prelec in J. Appl. Phys. 67, 671 (1990) proved that, in a low-pressure operating mode, hollow cathode discharges can have a two-component electron population, one of which is that of ''fast'' electrons having an energy corresponding to the cathode potential and a thermal spread of about 0.13 eV, which could form a basis for an excellent electron gun. Investigations of extracted electron currents in this low pressure mode indicate the existence of a narrow pressure range characterized by very high electron current extraction

  10. Formation of Ti-N graded bioceramic layer by DC hollow-cathode plasma nitriding

    Institute of Scientific and Technical Information of China (English)

    ZHENG Chuan-lin

    2004-01-01

    Ti-N graded ceramic layer was formed on titanium by using DC hollow-cathode plasma nitriding technique. The structure of Ti-N layer was analyzed using X-ray diffractometry(XRD) with Cu Kα radiation, and the microhardness( HV0.1) was measured from the surface to inner along the cross section of Ti-N layer. The results indicate that the Ti-N graded layer is composed of ε-Ti2 N, δ-TiN and α-Ti(N) phases. Mechanism discussion shows that hollow-cathode discharge can intensify gas ionization, increase current density and enhance the nitriding potential, which directly increases the thickness of the diffusion coatings compared with traditional nitriding methods.

  11. Spatio-temporal characteristics of self-pulse in hollow cathode discharge

    International Nuclear Information System (INIS)

    Jing, Ha; He, Shoujie

    2015-01-01

    The characteristics of self-pulse in hollow cathode discharge at low pressure have been investigated. The voltage-current (V-I) curves, the influence of ballast resistor on the self-pulses, and the evolution of current and voltage are measured. Both the axial and radial spatio-temporal discharge images of self-pulse are recorded. The results show that there exists the hysteresis effect in the present hollow cathode discharge. The high value of ballast resistors is favourable for the observation of self-pulses. The process of the self-pulse can be divided into three stages from the temporal discharge images, i.e., the pre-discharge, the transition from mainly axial electric field to mainly radial electric field, and the decaying process. The self-pulse is suggested to originate from the mode transition of the discharge in essence

  12. 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.

  13. Synthesis of diamond-like carbon via PECD using a streaming neutral gas injection hollow cathode

    International Nuclear Information System (INIS)

    Pacho, A.; Pares, E.; Ramos, H.; Mendenilla, A.; Malapit, G.

    2009-01-01

    A streaming neutral gas injection hollow cathode system was used to deposit diamond-like carbon films via plasma enhanced chemical vapor deposition on silicon and nickel-coated silicon substrates with acetylene and hydrogen as reactant gases. Samples were characterized using SEM and Raman spectroscopy. The work presented here aims to demonstrate the capability of the system to synthesize carbonaceous films and is starting point towards work on formation of carbon nanostructures. (author)

  14. Ionization and excitation of uranium in a hollow-cathode lamp

    International Nuclear Information System (INIS)

    Gagne, J.M.; Pianarosa, P.; Larin, G.; Saint-Dizier, J.P.; Bouchard, P.

    1981-01-01

    The influence of different carrier gases (Ne,Ar,Kr,Xe) their pressure, and discharge current on the excitation and ionization of uranium atoms in a vapor generator of hollow-cathode design has been investigated by monitoring emission line intensities. From our measurements of line intensities as a function of the carrier gas we obtain an indication of the role of Penning collisions on the excitation of radiative levels in U II

  15. Studies on the optogalvanic effect and isotope-selective excitation of ytterbium in a hollow cathode discharge lamp using a pulsed dye laser.

    Science.gov (United States)

    Kumar, Pankaj; Kumar, Jitendra; Prakash, Om; Saini, Vinod K; Dixit, Sudhir K; Nakhe, Shankar V

    2013-09-01

    This paper presents studies on the pulsed optogalvanic effect and isotope-selective excitation of Yb 555.648 nm (0 cm(-1) → 17 992.007 cm(-1)) and 581.067 nm (17 992.007 cm(-1) → 35 196.98 cm(-1)) transitions, in a Yb/Ne hollow cathode lamp. The Yb atoms were excited by narrow linewidth (500-1000 MHz) Rh110 and Rh6G dye based pulsed lasers. Optogalvanic signal inversion for ground state transition at 555.648 nm was observed beyond a hollow cathode discharge current of 8.5 mA, in contrast to normal optogalvanic signal at 581.067 nm up to maximum current of 14 mA. The isotope-selective excitation studies of Yb were carried out by recording Doppler limited optogalvanic signals as a function of dye laser wavelength. For the 581.067 nm transition, three even isotopes, (172)Yb, (174)Yb, and (176)Yb, and one odd isotope, (171)Yb, were clearly resolved. These data were compared with selective isotope excitation by 10 MHz linewidth continuous-wave dye laser. For 555.648 nm transition, isotopes were not clearly resolved, although isotope peaks of low modulation were observed.

  16. Spectra of Th/Ar and U/Ne hollow cathode lamps for spectrograph calibration

    Science.gov (United States)

    Nave, Gillian; Shlosberg, Ariel; Kerber, Florian; Den Hartog, Elizabeth; Neureiter, Bianca

    2018-01-01

    Low-current Th/Ar hollow cathode lamps have long been used for calibration of astronomical spectrographs on ground-based telescopes. Thorium is an attractive element for calibration as it has a single isotope, has narrow spectral lines, and has a dense spectrum covering the whole of the visible region. However, the high density of the spectrum that makes it attractive for calibrating high-resolution spectrographs is a detriment for lower resolution spectrographs and this is not obvious by examination of existing linelists. In addition, recent changes in regulations regarding the handling of thorium have led to a degradation in the quality of Th/Ar calibration lamps, with contamination by molecular ThO lines that are strong enough to obscure the calibration lines of interest.We are pursuing two approaches to these problems. First, we have expanded and improved the NIST Standard Reference Database 161, "Spectrum of Th-Ar Hollow Cathode Lamps" to cover the region 272 nm to 5500 nm. Spectra of hollow cathode lamps at up to 3 different currents can now be displayed simultaneously. Interactive zooming and the ability to convolve any of the spectra with a Gaussian or uploaded instrument profile enable the user to see immediately what the spectrum would look like at the particular resolution of their spectrograph. Second, we have measured the spectrum of a recent, contaminated Th/Ar hollow cathode lamp using a high-resolution Echelle spectrograph (Madison Wisconsin) at a resolving power (R~ 250,000). This significantly exceeds the resolving power of most astronomical spectrographs and resolves many of the molecular lines of ThO. With these spectra we are measuring and calibrating the positions of these molecular lines in order to make them suitable for spectrograph calibration.In the near infrared region, U/Ne hollow cathode lamps give a higher density of calibration lines than Th/Ar lamps and will be implemented on the upgraded CRIRES+ spectrograph on ESO’s Very Large

  17. Examining the effects of fill gas pressure on the distribution of copper atoms in a hollow cathode lamp

    International Nuclear Information System (INIS)

    Oliver, D.R.; Finlayson, T.R.

    1996-01-01

    A modified Copper Hollow Cathode lamp has been used to examine the effects of fill gas pressure on the distribution of sputtered Copper atoms in the body of the lamp. The lamp was modified by placing a quartz disc above the cathode, perpendicular to both the cathode bore and the cathode-anode axis. While the lamp is operating, some of the Copper that has been sputtered out of the cathode bore is deposited on the disc. Modified lamps have been operated at a variety of pressures, and the resulting deposition profiles recorded using an optical microscope. A summary of variations between different pressures are presented

  18. Statistical analysis on hollow and core-shell structured vanadium oxide microspheres as cathode materials for Lithium ion batteries

    Directory of Open Access Journals (Sweden)

    Xing Liang

    2018-06-01

    Full Text Available In this data, the statistical analyses of vanadium oxide microspheres cathode materials are presented for the research article entitled “Statistical analyses on hollow and core-shell structured vanadium oxides microspheres as cathode materials for Lithium ion batteries” (Liang et al., 2017 [1]. This article shows the statistical analyses on N2 adsorption-desorption isotherm and morphology vanadium oxide microspheres as cathode materials for LIBs. Keywords: Adsorption-desorption isotherm, Pore size distribution, SEM images, TEM images

  19. Heater Validation for the NEXT-C Hollow Cathodes

    Science.gov (United States)

    Verhey, Timothy R.; Soulas, George C.; Mackey, Jonathan A.

    2018-01-01

    Swaged cathode heaters whose design was successfully demonstrated under a prior flight project are to be provided by the NASA Glenn Research Center for the NEXT-C ion thruster being fabricated by Aerojet Rocketdyne. Extensive requalification activities were performed to validate process controls that had to be re-established or revised because systemic changes prevented reuse of the past approaches. A development batch of heaters was successfully fabricated based on the new process controls. Acceptance and cyclic life testing of multiple discharge and neutralizer sized heaters extracted from the development batch was initiated in August, 2016, with the last heater completing testing in April, 2017. Cyclic life testing results substantially exceeded the NEXT-C thruster requirement as well as all past experience for GRC-fabricated units. The heaters demonstrated ultimate cyclic life capability of 19050 to 33500 cycles. A qualification batch of heaters is now being fabricated using the finalized process controls. A set of six heaters will be acceptance and cyclic tested to verify conformance to the behavior observed with the development heaters. The heaters for flight use will be then be provided to the contractor from the remainder of the qualification batch. This paper summarizes the fabrication process control activities and the acceptance and life testing of the development heater units.

  20. Local Electric Field Strength in a Hollow Cathode Determined by Stark Splitting of the 2S Level of Hydrogen Isotopes by Optogalvanic Spectroscopy

    International Nuclear Information System (INIS)

    Perez, C.; Rosa, M. I. de la; Gruetzmacher, K.; Fuentes, L. M.; Gonzalo, A. B.

    2008-01-01

    In this work we present Doppler-free two-photon optogalvanic spectroscopy as a tool to measure the electric field strength in the cathode fall region of a hollow cathode discharge via the Stark splitting of the 2S level of atomic deuterium. The strong electric field strength present in the hollow cathode is determined for various discharge conditions which allows studying the corresponding variations of the cathode fall, and its changes with discharge operation time.

  1. The design and characteristics of direct current glow discharge atomic emission source operated with plain and hollow cathodes

    International Nuclear Information System (INIS)

    Qayyum, A.; Mahmood, M.I.

    2008-01-01

    A compact direct current glow discharge atomic emission source has been designed and constructed for analytical applications. This atomic emission source works very efficiently at a low-input electrical power. The design has some features that make it distinct from that of the conventional Grimm glow discharge source. The peculiar cathode design offered greater flexibility on size and shape of the sample. As a result the source can be easily adopted to operate in Plain or Hollow Cathode configuration. I-V and spectroscopic characteristics of the source were compared while operating it with plain and hollow copper cathodes. It was observed that with hollow cathode, the source can be operated at a less input power and generates greater Cu I and Cu II line intensities. Also, the intensity of Cu II line rise faster than Cu I line with argon pressure for both cathodes. But the influence of pressure on Cu II lines was more significant when the source is operated with hollow cathode

  2. Note: Hollow cathode lamp with integral, high optical efficiency isolation valve: A modular vacuum ultraviolet source

    International Nuclear Information System (INIS)

    Sloan Roberts, F.; Anderson, Scott L.

    2013-01-01

    The design and operating conditions of a hollow cathode discharge lamp for the generation of vacuum ultraviolet radiation, suitable for ultrahigh vacuum (UHV) application, are described in detail. The design is easily constructed, and modular, allowing it to be adapted to different experimental requirements. A thin isolation valve is built into one of the differential pumping stages, isolating the discharge section from the UHV section, both for vacuum safety and to allow lamp maintenance without venting the UHV chamber. The lamp has been used both for ultraviolet photoelectron spectroscopy of surfaces and as a “soft” photoionization source for gas-phase mass spectrometry

  3. Note: Hollow cathode lamp with integral, high optical efficiency isolation valve: A modular vacuum ultraviolet source

    Energy Technology Data Exchange (ETDEWEB)

    Sloan Roberts, F.; Anderson, Scott L. [Department of Chemistry, University of Utah, 315 S. 1400 E., Salt Lake City, Utah 84112 (United States)

    2013-12-15

    The design and operating conditions of a hollow cathode discharge lamp for the generation of vacuum ultraviolet radiation, suitable for ultrahigh vacuum (UHV) application, are described in detail. The design is easily constructed, and modular, allowing it to be adapted to different experimental requirements. A thin isolation valve is built into one of the differential pumping stages, isolating the discharge section from the UHV section, both for vacuum safety and to allow lamp maintenance without venting the UHV chamber. The lamp has been used both for ultraviolet photoelectron spectroscopy of surfaces and as a “soft” photoionization source for gas-phase mass spectrometry.

  4. Note: Hollow cathode lamp with integral, high optical efficiency isolation valve: a modular vacuum ultraviolet source.

    Science.gov (United States)

    Roberts, F Sloan; Anderson, Scott L

    2013-12-01

    The design and operating conditions of a hollow cathode discharge lamp for the generation of vacuum ultraviolet radiation, suitable for ultrahigh vacuum (UHV) application, are described in detail. The design is easily constructed, and modular, allowing it to be adapted to different experimental requirements. A thin isolation valve is built into one of the differential pumping stages, isolating the discharge section from the UHV section, both for vacuum safety and to allow lamp maintenance without venting the UHV chamber. The lamp has been used both for ultraviolet photoelectron spectroscopy of surfaces and as a "soft" photoionization source for gas-phase mass spectrometry.

  5. Characterization of an atom beam produced with the help of a hollow-cathode discharge

    International Nuclear Information System (INIS)

    Babin, F.; Gagne, J.

    1986-01-01

    A hollow-cathode type discharge is used as a refractory element vapor generator for the formation of an atomic beam. The development of the technique brings us to discuss its possibilities in spectroscopic studies of refractory elements. We focus primarily on the production of a uranium atomic beam and its characterization by laser-induced fluorescence spectroscopy. We determine, among other things, the beam divergence and the most probable velocity along its axis for specific current and pressure conditions in the discharge. We also discuss beam behavior with respect to buffer gas pressure and electric current in the discharge

  6. Simple method for identifying doubly ionized uranium (U III) produced in a hollow-cathode discharge

    International Nuclear Information System (INIS)

    Piyakis, K.N.; Gagne, J.M.

    1988-01-01

    We have studied by emission spectroscopy the spectral properties of doubly ionized uranium, produced in a vapor generator of hollow-cathode design, as a function of the nature of a pure fill gas (helium, neon, argon, krypton, xenon) and its pressure. The spectral intensity is found to increase with increasing ionization potential of the discharge buffer gas, except in the case of helium. Based on our preliminary results, a simple and practical method for the positive identification of the complex U III spectrum is suggested

  7. Hot ion plasma production in HIP-1 using water-cooled hollow cathodes

    Science.gov (United States)

    Reinmann, J. J.; Lauver, M. R.; Patch, R. W.; Layman, R. W.; Snyder, A.

    1975-01-01

    A steady-state ExB plasma was formed by applying a strong radially inward dc electric field near the mirror throats. Most of the results were for hydrogen, but deuterium and helium plasmas were also studied. Three water-cooled hollow cathodes were operated in the hot-ion plasma mode with the following results: (1) thermally emitting cathodes were not required to achieve the hot-ion mode; (2) steady-state operation (several minutes) was attained; (3) input powers greater than 40 kW were achieved; (4) cathode outside diameters were increased from 1.2 cm (uncooled) to 4.4 cm (water-cooled); (5) steady-state hydrogen plasma with ion temperatures from 185 to 770 eV and electron temperatures from 5 to 21 eV were produced. Scaling relations were empirically obtained for discharge current, ion temperature, electron temperature, and relative ion density as a function of hydrogen gas feed rate, magnetic field, and cathode voltage. Neutrons were produced from deuterium plasma, but it was not established whether thay came from the plasma volume or from the electrode surfaces.

  8. The effect of self-absorption in hollow cathode lamp on its temperature

    International Nuclear Information System (INIS)

    Sobhanian, S.; Naghshara, H.

    2014-01-01

    It has been shown experimentally that even a small error in the calculation of the temperature inside the hollow-cathode lamp (HCL) and the current applied to the lamp, may cause a tremendous error in determination of the absorption ratio in optical resonance absorption (ORA) method. This effect is intensified nonlinearity for large absorption ratios. If a higher current is applied to a copper hollow cathode lamp, the copper density inside the lamp is increasing rapidly. Due to the cylindrical (axisymmetric) form of the lamp, the density of atoms around the main axis of the lamp becomes greater than that near the internal wall. In this case the auto-absorption (or self-absorption) is occurred and as its result, the emission spectrum produced by copper atoms is locally absorbed before going out from the lamp. This absorption is stronger near the main axis compared with the areas near the wall because of the Gaussian profile of the spectral line. Two different Cu atoms ground state lines with the similar lower state (327.4 nm and 324.7 nm) are used in this work as optical resonance absorption and the absorption coefficient is obtained for three different pressures (0.6, 4.5 and 14 µbar). The best values for copper HCL temperature and for maximum HCL current were found respectively 450 K, and 5mA. (author)

  9. Ionization Waves in a Fast, Hollow-Cathode-Assisted Capillary Discharge

    International Nuclear Information System (INIS)

    Rutkevich, I.; Mond, M.; Kaufman, Y.; Choi, P.; Favre, M.

    1999-01-01

    The initial, low-current stage of the evolution of a soft x-ray emitting, hollow-cathode-assisted capillary discharge initiated by a steep high-voltage pulse is investigated. The capillary is surrounded by a shield having the cathode potential. The mean electric field E of the order of 10 kV/cm and the low gas pressure (P<1Torr) provide conditions for extensive electron runaway. This is taken into account in the formulation of the theoretical approach by retaining the inertial terms in the momentum equation for the electrons. In addition, the ionization rate is calculated by considering the cross section for ionization by high-energy electrons. The two-dimensional system of the basic equations is reduced to a system of one-dimensional equations for the axial distributions of the physical quantities by introducing appropriate radial profiles of the electric potential, and the electron gas parameters and satisfying the electrodynamic boundary conditions at the capillary wall and at the shield. The resulting system of equations admits solutions in the form of stationary ionization waves transferring the anode potential to the cathode end. Numerical calculations of such solutions for argon show that the wave velocity V increases with the gas pressure P and with the density of initial electron beam ejected from the cathode hole ahead of the ionization front, while the dependence of V on the applied voltage is weak. At the instant when the virtual anode reaches the cathode hole, the plasma in the capillary is not yet fully ionized. The traverse time of the ionization wave along the capillary calculated for various gas pressures is in reasonable agreement with experimentally registered time delay for a high-current stage resulting in voltage collapse and soft x-ray emission

  10. Use of a discharge in an hollow cathode as neutral atom source for resonant ionization mass spectrometry

    International Nuclear Information System (INIS)

    Berthoud, T.; Briand, A.; Khelifa, N.; Mauchien, P.

    1987-01-01

    The resonance ionization mass spectrometry in our laboratory is aimed at simplification of isotope measurements of elements present in mixtures and at measurement of very small isotopes. An atomization source which produces an atomic beam collimated from a discharge in a hollow cathode has been developed. First results of this spectrometry with an uranium atomic jet are presented [fr

  11. Characteristics of an elongated plasma column produced by magnetically coupled hollow cathode plasma source

    Science.gov (United States)

    Bhuva, M. P.; Karkari, S. K.; Kumar, Sunil

    2018-03-01

    An elongated plasma column in the presence of an axial magnetic field has been formed using a cylindrical hollow cathode (HC) and a constricted anode (CA). The plasma characteristics of the central line have been found to vary with the magnetic field strength and the axial distance from the source. It is believed that the primary electrons constituting the discharge current are steered by the axial magnetic field to undertake ionizing collisions along the plasma column. The current carrying electrons from the HC reach the anode by cross-field diffusion towards the central line. The above observation has been substantiated using a phenomenological model which links the observed characteristics of the source with the plasma column. The experimental results are found to be in qualitative agreement with the model.

  12. Experimental study of the hollow cathode radio-frequency plasma mixture: Argon-Oxygen

    International Nuclear Information System (INIS)

    Saloum, S.; Naddaf, M.

    2008-01-01

    This study presents experimental results of plasma gas mixture Ar-O 2 for different mixing ratios in radio-frequency hollow cathode plasma. The following plasma parameters have been investigated: The electronic temperature, plasma potential, floating potential, emission atomic lines intensities, as a function of some variables, where the effect of power has been studied in the range [100-300 W], and the effect of pressure has been studied in the range [0.05-0.3 mbar]. The effect of relative composition has been studied for a fixed power and pressure. Two diagnostic techniques have been employed: Optical emission spectroscopy and langmuir probe. The most important result of this study is the ability to measure the relative atomic density of oxygen by optical emission spectroscopy, where the maximum of this density is obtained for the mixture 40% Ar - 60% O 2 . (author)

  13. Acoustic emission by self-organising effects of micro-hollow cathode discharges

    Science.gov (United States)

    Kotschate, Daniel; Gaal, Mate; Kersten, Holger

    2018-04-01

    We designed micro-hollow cathode discharge prototypes under atmospheric pressure and investigated their acoustic characteristics. For the acoustic model of the discharge, we correlated the self-organisation effect of the current density distribution with the ideal model of an acoustic membrane. For validation of the obtained model, sound particle velocity spectroscopy was used to detect and analyse the acoustic emission experimentally. The results have shown a behaviour similar to the ideal acoustic membrane. Therefore, the acoustic excitation is decomposable into its eigenfrequencies and predictable. The model was unified utilising the gas exhaust velocity caused by the electrohydrodynamic force. The results may allow a contactless prediction of the current density distribution by measuring the acoustic emission or using the micro-discharge as a tunable acoustic source for specific applications as well.

  14. Absolute atomic hydrogen density distribution in a hollow cathode discharge by two-photon polarization spectroscopy

    International Nuclear Information System (INIS)

    Gonzalo, A B; Rosa, M I de la; Perez, C; Mar, S; Gruetzmacher, K

    2004-01-01

    We report on quantitative measurements of ground-state atomic hydrogen densities in a stationary plasma far off thermodynamic equilibrium, generated in a hollow cathode discharge, by two-photon polarization spectroscopy via the 1S-2S transition. Absolute densities are obtained using a well established calibration method based on the non-resonant two-photon polarization signal of xenon gas at room temperature, which serves as the reference at the wavelength of the hydrogen transition. This study is dedicated to demonstrating the capability of two-photon polarization spectroscopy close to the detection limit. Therefore, it requires single-longitudinal mode UV-laser radiation provided by an advanced UV-laser spectrometer

  15. Population distribution of atomic uranium in the afterglow of a pulsed hollow-cathode discharge

    International Nuclear Information System (INIS)

    Demers, Yves; Gagne, J.-M.; Pianarosa, Piero

    1987-01-01

    From laser absorption measurements we have deduced the time evolution of the population distribution of atomic uranium in the afterglow of a pulsed hollow-cathode type discharge. The vapour generator operates with xenon as the discharge sustaining gas at a pressure of 280 Pa (2.1 Torr). The current pulse characteristics are width 250 μs and height 1.5 A. The pulse repetition frequency is 100 Hz. It is shown that the populations in the three metastable levels at 6249, 3868 and 3800 cm -1 decrease almost exponentially in a time interval between 150 and 300 μs. From 400 μs onwards in the afterglow, the atom population is essentially shared between the ground and the first metastable (620 cm -1 ) levels. Furthermore, starting from 9 ms in the afterglow more than 80% of the U atoms are found in the ground level. (author)

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

    Science.gov (United States)

    Saini, V. K.; Kumar, P.; Sarangpani, K. K.; Dixit, S. K.; Nakhe, S. V.

    2017-09-01

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

  17. Construction and characterization of a hollow cathode tube for high sensibility laser spectroscopy

    International Nuclear Information System (INIS)

    Morage, A.; Motta, C.C.

    1998-01-01

    A new hollow cathode tube argon-iron design was developed to be used in laser atomic spectroscopy experiments, were high sensibility is required. This tube was employed in order to allow laser absorption and optogalvanic signal measurements. The tube also included fused-quartz Brewster angle windows aligned with the optical axis in each ending of the tube. Therefore, in this configuration a minimum laser intensity losses through the windows can be attained for the appropriate light polarization. The optogalvanic signal detection was accomplished using a tunable dye laser resonant with the Ar, 3p 5 4p ( 3 S 1 )--> 3p 5 4d ( 3 D 1 0 ) transition, that corresponds to 591.2 nm in air. It was also possible to determine the gas temperature by measuring the Doppler line broadening and the results were compared to those obtained from a theoretical model for gas heat conduction. To measure the temperature of the cathode external surface a thermocouple was used inside the tube. The analysis of results showed that a high signal to noise ratio can be obtained with this tube configuration, that permits experimental investigation of electronic transitions presenting low light absorption cross sections. (author)

  18. Space and Temporal Correlation between the Moving Virtual Anode and the Ionization Growth in a Transient Hollow Cathode Discharge

    International Nuclear Information System (INIS)

    Zambra, M.; Moreno, J.; Soto, L.; Silva, P.; Sylvester, G.; Alarcon, H.

    2001-01-01

    A Transient Hollow Cathode Discharge is a low-pressure high-voltage electric discharge between plane parallel electrodes with an axial hole in the cathode. There are essential ionization events which lead to final electrical breakdown, between them the enhanced ionization processes taking place inside the Hollow Cathode Region (HCR) and the virtual anode moving in the interelectrode region, which extends the anode potential to within the HCR. In previous works it was studied the virtual anode speed in the A-K gap and the temporal evolution of the ionization growth in the HCR separately. In this paper, the virtual anode speed has been studied temporal and space correlated with the ionization growth inside the HCR. The presence of the moving virtual anode and the ionization growth has been diagnosed by means of capacitive probes and observing the light emission at 656 nm (H-α) from a point behind the cathode aperture respectively. The discharge was operated in hydrogen gas, at pressure in the range 100-300 mTorr, with 5 mm cathode aperture and at 30 kV maximum voltage. (author)

  19. Low pressure arc discharges with hollow cathodes and their using in plasma generators and charged particle sources

    CERN Document Server

    Vintizenko, L G; Koval, N N; Tolkachev, V S; Lopatin, I V; Shchanin, P M

    2001-01-01

    Paper presents the results of investigation into arc discharges with a hollow cathode generating 10 sup 1 sup 0 -10 sup 1 sup 2 concentration gas-discharge plasma in essential (approx 1 m sup 3) volumes at low (10 sup - sup 2 -1 Pa) pressures and up to 200 A discharge currents. One studied design of discharge systems with heated and cold cathodes their peculiar features, presented the parameters of plasma generators and of charged particle sources based on arc discharges and discussed, as well, the problems of more rational application of those systems in the processes for surface modification of solids

  20. Connection experiments with a hollow cathode ion source and a helium gas jet system for on-line isotope separation

    International Nuclear Information System (INIS)

    Mazumdar, A.K.; Wagner, H.; Walcher, W.; Lund, T.

    1976-01-01

    A helium jet system was connected to a hollow cathode ion source. Using fission products the efficiencies of the different steps were measured by β-, X-ray and γ-counting while the mass spectrum and the focussing of the extracted ion beam were observed with a small deflecting magnet. Mean transport efficiencies of 50% through the 12 m capillary were obtained and ion source efficiencies in the percent range for several elements. (Auth.)

  1. Dependence of electron peak current on hollow cathode dimensions and seed electron energy in a pseudospark discharge

    International Nuclear Information System (INIS)

    Cetiner, S. O.; Stoltz, P.; Messmer, P.; Cambier, J.-L.

    2008-01-01

    The prebreakdown and breakdown phases of a pseudospark discharge are investigated using the two-dimensional kinetic plasma simulation code OOPIC PRO. Trends in the peak electron current at the anode are presented as function of the hollow cathode dimensions and mean seed injection velocities at the cavity back wall. The plasma generation process by ionizing collisions is examined, showing the effect on supplying the electrons that determine the density of the beam. The mean seed velocities used here are varied between the velocity corresponding to the energy of peak ionization cross section, 15 times this value and no mean velocity (i.e., electrons injected with a temperature of 2.5 eV). The reliance of the discharge characteristics on the penetrating electric field is shown to decrease as the mean seed injection velocity increases because of its ability to generate a surplus plasma independent of the virtual anode. As a result, the peak current increases with the hollow cathode dimensions for the largest average injection velocity, while for the smallest value it increases with the area of penetration of the electric field in the hollow cathode interior. Additionally, for a given geometry an increase in the peak current with the surplus plasma generated is observed. For the largest seed injection velocity used a dependence of the magnitude of the peak current on the ratio of the hole thickness and hollow cathode depth to the hole height is demonstrated. This means similar trends of the peak current are generated when the geometry is resized. Although the present study uses argon only, the variation in the discharge dependencies with the seed injection energy relative to the ionization threshold is expected to apply independently of the gas type. Secondary electrons due to electron and ion impact are shown to be important only for the largest impact areas and discharge development times of the study

  2. In situ plasma diagnostics study of a commercial high-power hollow cathode magnetron deposition tool

    International Nuclear Information System (INIS)

    Meng Liang; Raju, Ramasamy; Flauta, Randolph; Shin, Hyungjoo; Ruzic, David N.; Hayden, Douglas B.

    2010-01-01

    Using a newly designed and built plasma diagnostic system, the plasma parameters were investigated on a commercial 200 mm high-power hollow cathode magnetron (HCM) physical vapor deposition tool using Ta target under argon plasma. A three dimensional (3D) scanning radio frequency (rf)-compensated Langmuir probe was constructed to measure the spatial distribution of the electron temperature (T e ) and electron density (n e ) in the substrate region of the HCM tool at various input powers (2-15 kW) and pressures (10-70 mTorr). The T e was in the range of 1-3 eV, scaling with decreasing power and decreasing pressure. Meanwhile, n e was in the range of 4x10 10 -1x10 12 cm -3 scaling with increasing power and decreasing pressure. As metal deposits on the probe during the probe measurements, a self-cleaning plasma cup was designed and installed in the chamber to clean the tungsten probe tip. However, its effectiveness in recovering the measured plasma parameters was hindered by the metal layer deposited on the insulating probe tube which was accounted for the variation in the plasma measurements. Using a quartz crystal microbalance combined with electrostatic filters, the ionization fraction of the metal flux was measured at various input power of 2-16 kW and pressure of 5-40 mTorr. The metal ionization fraction reduced significantly with the increasing input power and decreasing gas pressure which were attributed to the corresponding variation in the ionization cross section and the residence time of the sputtered atoms in the plasma, respectively. Both the metal neutral and ion flux increased at higher power and lower pressure. The 3D measurements further showed that the ionization fraction decreased when moving up from the substrate to the cathode.

  3. Transition Metal Hollow Nanocages as Promising Cathodes for the Long-Term Cyclability of Li–O2 Batteries

    Directory of Open Access Journals (Sweden)

    Amrita Chatterjee

    2018-05-01

    Full Text Available As a step towards efficient and cost-effective electrocatalytic cathodes for Li–O2 batteries, highly porous hausmannite-type Mn3O4 hollow nanocages (MOHNs of a large diameter of ~250 nm and a high surface area of 90.65 m2·g−1 were synthesized and their physicochemical and electrochemical properties were studied in addition to their formation mechanism. A facile approach using carbon spheres as the template and MnCl2 as the precursor was adopted to suit the purpose. The MOHNs/Ketjenblack cathode-based Li–O2 battery demonstrated an improved cyclability of 50 discharge–charge cycles at a specific current of 400 mA·g−1 and a specific capacity of 600 mAh·g−1. In contrast, the Ketjenblack cathode-based one can sustain only 15 cycles under the same electrolytic system comprised of 1 M LiTFSI/TEGDME. It is surmised that the unique hollow nanocage morphology of MOHNs is responsible for the high electrochemical performance. The hollow nanocages were a result of the aggregation of crystalline nanoparticles of 25–35 nm size, and the mesoscopic pores between the nanoparticles gave rise to a loosely mesoporous structure for accommodating the volume change in the MOHNs/Ketjenblack cathode during electrocatalytic reactions. The improved cyclic stability is mainly due to the faster mass transport of the O2 through the mesoscopic pores. This work is comparable to the state-of-the-art experimentations on cathodes for Li–O2 batteries that focus on the use of non-precious transition materials.

  4. Time resolved diagnostics and kinetic modelling of a modulated hollow cathode discharge of NO2

    International Nuclear Information System (INIS)

    Castillo, M; Herrero, V J; Mendez, I; Tanarro, I

    2004-01-01

    The transients associated with the ignition and the extinction of the cold plasma produced in a low frequency, square-wave modulated, hollow cathode discharge of nitrogen dioxide are characterized by time resolved emission spectroscopy, mass spectrometry and electrical probes. The temporal evolution of the concentrations of neutral species created or destroyed in the NO 2 discharges are compared with the predictions of a simple kinetic model previously developed for discharges of other nitrogen oxides (N 2 O and NO). The physical conditions of pressure, gas flow rate, modulation frequency and electrical current in the NO 2 plasma were selected in order to highlight the time-dependent behaviour of some of the stable species formed in the discharge, especially the nitrogen oxide products, whose concentrations show transient maxima. The usefulness of the analysis of the transient results is emphasized as a means to evaluate the relevance of the different elementary processes and as a key to estimate the values of some of the rate constants critical to the modelling. This work is dedicated to the memory of Professor Jose Campos

  5. Studies on pulsed optogalvanic effect in Eu/Ne hollow cathode discharge.

    Science.gov (United States)

    Saini, V K; Kumar, P; Dixit, S K; Nakhe, S V

    2014-07-01

    The optogalvanic (OG) effect has been observed in a Eu/Ne hollow cathode discharge lamp using pulsed laser irradiation. An OG spectrum is recorded in dye laser wavelength region 574–602 nm using a boxcar-averager. In total 41 atomic lines are observed. Of these, 38 lines are assigned to neon transitions. Two lines observed corresponding to wavelengths 576.519 and 601.815 nm are assigned to europium transitions; (4f 7 6s 2 , S 8 7/2 →4f 7 6s6p , zP 6 7/2 ) and (4f 7 6s 2 , S 8 7/2 →4f 7 6s6p , zP 8 9/2 ), respectively, and the remaining line at 582.475 nm could not be assigned. The effect of the discharge current on europium as well as neon OG signals is also studied. At moderate discharge current values, an extra positive peak is observed in neon OG signal for the transition (1s 5 →2p 2 ) at 588.189 nm, which is explained by Penning-ionization process using the quasi-resonant energy transfer interactions between excited neon and europium atoms lying in 2p 2 and D 10 9/2 states, respectively.

  6. Heat input properties of hollow cathode arc as a welding heat source

    International Nuclear Information System (INIS)

    Nishikawa, Hiroshi; Shobako, Shinichiro; Ohta, Masashi; Ohji, Takayoshi

    2005-01-01

    In order to clarify whether a hollow cathode arc (HCA) can be used as a welding heat source in space, investigations into the fundamental characteristics of HCA were experimentally performed under low pressure conditions. The HCA method enables an arc discharge to ignite and maintain under low pressure conditions; in contrast, low pressure conditions make it extremely difficult for the conventional gas tungsten arc method to form an arc discharge. In an earlier paper, it was shown that the melting process by HCA is very sensitive to process parameters such as the gas flow rate and arc length, and a deep penetration forms when the arc length is long and the gas flow rate is low. In this paper, the distribution of the arc current on the anode surface and the plasma properties of the HCA under low pressure conditions have been made clear and the total heat energy to the anode has been discussed in order to understand the heat input properties of the HCA. The result shows that the HCA in the case of a low gas flow rate is a high and concentrated energy source, and the high energy input to the anode contributes to the deep penetration

  7. Three-dimensional interconnected cobalt oxide-carbon hollow spheres arrays as cathode materials for hybrid batteries

    Directory of Open Access Journals (Sweden)

    Jiye Zhan

    2016-06-01

    Full Text Available Hierarchical porous metal oxides arrays is critical for development of advanced energy storage devices. Herein, we report a facile template-assisted electro-deposition plus glucose decomposition method for synthesis of multilayer CoO/C hollow spheres arrays. The CoO/C arrays consist of multilayer interconnected hollow composite spheres with diameters of ∼350 nm as well as thin walls of ∼20 nm. Hierarchical hollow spheres architecture with 3D porous networks are achieved. As cathode of high-rate hybrid batteries, the multilayer CoO/C hollow sphere arrays exhibit impressive enhanced performances with a high capacity (73.5 mAh g−1 at 2 A g−1, and stable high-rate cycling life (70 mAh g−1 after 12,500 cycles at 2 A g−1. The improved electrochemical performance is owing to the composite hollow-sphere architecture with high contact area between the active materials and electrolyte as well as fast ion/electron transportation path.

  8. Note: Possibilities of detecting the trace-level erosion products from an electric propulsion hollow cathode plasma source by the method of time-of-flight mass spectrometry

    Science.gov (United States)

    Ning, Zhong-Xi; Zhang, Hai-Guang; Zhu, Xi-Ming; Jiang, Bin-Hao; Zhou, Zhong-Yue; Yu, Da-Ren; An, Bing-Jian; Wang, Yan-Fei

    2018-02-01

    A hollow cathode produces electrons which neutralize ions from electric propulsion thrusters. After hundreds to thousands of hours of operation in space, the cathode materials can be significantly eroded due to ion bombardment. As a result, the electric propulsion system performance will be obviously changed or even fail. In this work, the erosion products from a LaB6 hollow cathode (widely used presently in electric propulsion systems) are studied by using a specific detection system, which consists of a molecular beam sampler and a time-of-flight mass spectrometer. This system measures trace-level-concentration (10-6-10-3) products. Boron (B), tantalum (Ta), and tungsten (W)—originating from the emitter, keeper, and orifice of the hollow cathode—are measured. It is found that the erosion rate is significantly influenced by the gas flow rate to the cathode.

  9. Experiments with a large sized hollow cathode discharge fed with argon

    International Nuclear Information System (INIS)

    Bastian, C.; Boeschoten, F.; Hekman, H.; Komen, R.; Riske, H.P.; Iersel, A. van.

    1974-04-01

    Several plasma parameters which are pertinent to the rotation of the plasma column of the hollow cathode discharge ''John Luce'' were measured. Several improvements to the device were made, notably concerning the construction of the electrodes and their supports. The ion temperature, Tsub(i), was measured with a Fabry-Perot interferometer; depending on arc current and gas flow Tsub(i) may be varied in argon arc in the range 1-10 eV. The magnetic field strength, B, is adjustable from 600-6000 Gauss. The plasma column is fully ionized, and for higher values of Tsub(i) and B it is also fully magnetized (ωsub(ci)tausub(i) > 1). Simultaneous Doppler-shift measurements of the Asup(II) line 4806 A reveal that the plasma column rotates non-uniformly around its axis. (Order of magnitude of angular frequency is 10 5 rad/sec.) At larger distances from the axis the rotation was measured with a pendulum and with a directional Langmuir Probe. The object of the experiments is to disclose the connection between this rotation and the stability of the plasma column. Langmuir Probes are used to measure radial density profiles under various conditions in the arc. A flat probe with its normal to the surface pointing in radial direction makes reliable ion density measurements possible, even in the presence of a magnetic field. Floating potential measurements were used in order to estimate the radial electric field strength and the drift velocity which is related to it. The electron temperature, Tsub(e), is measured with less accuracy

  10. Hierarchical nanostructured hollow spherical carbon with mesoporous shell as a unique cathode catalyst support in proton exchange membrane fuel cell.

    Science.gov (United States)

    Fang, Baizeng; Kim, Jung Ho; Kim, Minsik; Kim, Minwoo; Yu, Jong-Sung

    2009-03-07

    Hierarchical nanostructured spherical carbon with hollow macroporous core in combination with mesoporous shell has been explored to support Pt cathode catalyst with high metal loading in proton exchange membrane fuel cell (PEMFC). The hollow core-mesoporous shell carbon (HCMSC) has unique structural characteristics such as large specific surface area and mesoporous volume, ensuring uniform dispersion of the supported high loading (60 wt%) Pt nanoparticles with small particle size, and well-developed three-dimensionally interconnected hierarchical porosity network, facilitating fast mass transport. The HCMSC-supported Pt(60 wt%) cathode catalyst has demonstrated markedly enhanced catalytic activity toward oxygen reduction and greatly improved PEMFC polarization performance compared with carbon black Vulcan XC-72 (VC)-supported ones. Furthermore, the HCMSC-supported Pt(40 wt%) or Pt(60 wt%) outperforms the HCMSC-supported Pt(20 wt%) even at a low catalyst loading of 0.2 mg Pt cm(-2) in the cathode, which is completely different from the VC-supported Pt catalysts. The capability of supporting high loading Pt is supposed to accelerate the commercialization of PEMFC due to the anticipated significant reduction in the amount of catalyst support required, diffusion layer thickness and fabricating cost of the supported Pt catalyst electrode.

  11. Laser beam absorption study of a 238U(5L60) vapor obtained with a hollow cathode lamp

    International Nuclear Information System (INIS)

    Gagne, J.M.; Leblanc, B.; Mongeau, B.; Carleer, M.; Bertrand, L.

    1979-01-01

    The density of U atoms in the 5 L 0 6 ground state present in a vapor of this element from a hollow cathode lamp has been measured using laser absorption spectroscopy. The influence of the carrier gases (Ar, Kr, Xe) on the density, the absorption coefficient profiles, and on the ratio of U atoms to the dissipated electrical power has been investigated. It has been found that, in our range of operating conditions, the xenon gas is the most efficient. With xenon, a density of 2.2 x 10 12 cm -3 ground-state U atoms is obtained when the lamp dissipates 40 W of electrical power

  12. Hollow cathode discharges with gas flow: numerical modelling for the effect on the sputtered atoms and the deposition flux

    International Nuclear Information System (INIS)

    Bogaerts, Annemie; Okhrimovskyy, Andriy; Baguer, Neyda; Gijbels, Renaat

    2005-01-01

    A model is developed for a cylindrical hollow cathode discharge (HCD), with an axial gas flow (entering through a hole in the cathode bottom). The model combines a commercial computational fluid dynamics program 'FLUENT' to compute the gas flow, with home-developed Monte Carlo and fluid models for the plasma behaviour. In this paper, we focus on the behaviour of the sputtered atoms, and we investigate how the gas flow affects the sputtered atom density profiles and the fluxes, which is important for sputter deposition. The sputtered atom density profiles are not much affected by the gas flow. The flux, on the other hand, is found to be significantly enhanced by the gas flow, but in the present set-up it is far from uniform in the radial direction at the open end of the HCD, where a substrate for deposition could be located

  13. Electric field measurements in a hollow cathode discharge by two-photon polarization spectroscopy of atomic deuterium

    International Nuclear Information System (INIS)

    Rosa, M I de la; Perez, C; Gruetzmacher, K; Gonzalo, A B; Steiger, A

    2006-01-01

    The local electric field strength (E-field) is an important parameter to be known in low pressure plasmas such as glow discharges, RF and microwave discharges, plasma boundaries in tokamaks etc. In this paper, we demonstrate, for the first time, the potential of two-photon polarization spectroscopy measuring the E-field in the cathode fall region of a hollow cathode discharge, via Doppler-free spectra of the Stark splitting of the 2S level of atomic deuterium. Electric field strength is determined in the range from 2 to 5 kV cm -1 . Compared with LIF, this method has several advantages: it is not affected by background radiation, it can be applied without limitation at elevated pressure and it allows simultaneous measurement of absolute local atomic ground state densities of hydrogen isotopes

  14. Physics and applications of micro-plasmas in dielectric barrier and hollow cathode configurations

    International Nuclear Information System (INIS)

    Boeuf, J. P.; Pitchford, L. C.

    2005-01-01

    Non-equilibrium or non-thermal plasmas operate at low gas temperatures and this property make these plasmas very attractive in a number of applications, from etching and deposition in the microelectronics industry to plasma displays and pollution control. However, although it is quite easy to generate a large volume non-equilibrium plasma at pressure on the order or below 100 Pa, this is more of a challenge around atmospheric pressure. Large area plasma sources operating at atmospheric pressure represent a very cost-effective solution for material processing, light sources and other applications, and a large research effort has been devoted to the development of such sources in the last ten years. Dielectric Barrier Discharges (DBDs), where one or both electrodes are covered with a dielectric layer are good candidates for atmospheric non-equilibrium plasma generation because of their ability to limit the current and power deposition. It is also much easier to control an atmospheric discharge in a small volume. Therefore an atmospheric plasma source often consists of a number of micro-discharges arranged in a way that depends on the application. Even in DBDs with large electrode areas, the plasma is generally not uniform and consists in a large number of micro-discharges or filaments. In this lecture we present a discussion of the physical properties of non-equilibrium plasmas generated in different configurations and operating at atmospheric pressure. This discussion is based on results from numerical models and simulations of Dielectric Barrier Discharges to Micro-Hollow Cathode Discharges. We then focus on specific applications such as surface DBDs for flow control. These discharges (which have some similarities with the surface micro-discharges used in Plasma Display Panels) are being studied for their ability to modify the properties of the boundary layer along airfoils and hence to control the transition between laminar and turbulent regimes. We will show how

  15. Study of the use of an electric discharge for hollow cathodes used as optical excitation sources in the spectrographic measurement of fluorine in thorium, uranium and plutonium

    International Nuclear Information System (INIS)

    Bufpereau, M.; Crehange, G.; Poublan, J.

    1964-01-01

    Previous works and phenomena concerned with a hollow cathode excitation are reviewed. Experiments aimed specially on the determination of the best conditions for an analysis of fluorine in oxides-metals and solutions. In that purpose, several factors have been pointed out. One started some researches about others elements that fluorine. Carrying fluorine into discharge and excitation have been more specially studied. A quantitative analysis method is given. The analysis limit is 45 ppm about but the detection limit is 5 ppm about. As a conclusion, various ways for optical excitation of fluorine are reviewed as other analytical possibilities a hollow cathode discharge offers. (authors) [fr

  16. Investigation of modified thin SnO2 layers treated by rapid thermal annealing by means of hollow cathode spectroscopy and AFM technique

    International Nuclear Information System (INIS)

    Djulgerova, R; Popova, L; Beshkov, G; Petrovic, Z Lju; Rakocevic, Z; Mihailov, V; Gencheva, V; Dohnalik, T

    2006-01-01

    By means of hollow cathode spectroscopy and atomic force microscopy the surface morphology and composition of SnO 2 thin film, modified with hexamethyldisilazane after rapid thermal annealing treatment (800-1200 deg. C), are investigated. Formation of crystalline structure is suggested at lower temperatures. Depolimerization, destruction and dehydration are developed at temperatures of 1200 deg. C. It is shown that the rapid thermal annealing treatment could modify both the surface morphology and the composition of the layer, thus changing the adsorption ability of the sensing layer. The results confirm the ability of hollow cathode emission spectroscopy for depth profiling of new materials especially combined with standard techniques

  17. Enhancement of opto-galvanic signals in the hollow cathode dark space: application to single colour 3-photon ionization of uranium

    International Nuclear Information System (INIS)

    Pradhan, S.; Manohar, K.G.; Marathe, A.; Rawat, V.S.; Sridhar, G.; Singh, S.; Jagatap, B.N.; Gantayet, L.M.

    1999-01-01

    Opto-galvanic effect in a hollow cathode lamp offers a very convenient method of spectroscopy of many elements of interest including refractory elements like uranium. The dependence of opto-galvanic signals on various discharge parameters like buffer gas pressure, buffer gas type, discharge current, diameter of the hollow cavity of the cathode etc. have been studied. Various mechanisms for the generation of opto-galvanic signals based on electron impact ionization and super elastic collisions have been proposed. It appears that both these processes do contribute to the opto-galvanic signals simultaneously, under specific discharge conditions

  18. Doppler spectroscopy of hydrogen Balmer lines in a hollow cathode glow discharge in ammonia and argon-ammonia mixture

    International Nuclear Information System (INIS)

    Sisovic, N. M.; Konjevic, N.

    2008-01-01

    The results of Doppler spectroscopy of hydrogen Balmer lines from a stainless steel (SS) and copper (Cu) hollow cathode (HC) glow discharge in ammonia and argon-ammonia mixture are reported. The experimental profiles in ammonia discharge are fitted well by superposing three Gaussian profiles. The half widths, in energy units, of narrow and medium Gaussians are in the ranges 0.3-0.4 eV and 3-4 eV, respectively, for both hollow cathodes what is expected on the basis of earlier electron beam→NH 3 experiments. The half widths of the largest Gaussian in ammonia are 46 and 55 eV for SS and Cu HC, respectively. In argon-ammonia discharge, three Gaussians are also required to fit experimental profiles. While half widths of narrow and medium Gaussians are similar to those in ammonia, the half widths of the largest Gaussians are 35 and 42 eV for SS and Cu HC, respectively. The half widths of the largest Gaussians in ammonia and in argon-ammonia mixture indicate the presence of excessive Doppler broadening.

  19. Dual-Function Electrocatalytic and Macroporous Hollow-Fiber Cathode for Converting Waste Streams to Valuable Resources Using Microbial Electrochemical Systems

    KAUST Repository

    Katuri, Krishna; Kalathil, Shafeer; Ragab, Ala'a; Bian, Bin; AlQahtani, Manal Faisal; Pant, Deepak; Saikaly, Pascal

    2018-01-01

    Dual-function electrocatalytic and macroporous hollow-fiber cathodes are recently proposed as promising advanced material for maximizing the conversion of waste streams such as wastewater and waste CO2 to valuable resources (e.g., clean freshwater, energy, value-added chemicals) in microbial electrochemical systems. The first part of this progress report reviews recent developments in this type of cathode architecture for the simultaneous recovery of clean freshwater and energy from wastewater. Critical insights are provided on suitable materials for fabricating these cathodes, as well as addressing some challenges in the fabrication process with proposed strategies to overcome them. The second and complementary part of the progress report highlights how the unique features of this cathode architecture can solve one of the intrinsic bottlenecks (gas-liquid mass transfer limitation) in the application of microbial electrochemical systems for CO2 reduction to value-added products. Strategies to further improve the availability of CO2 to microbial catalysts on the cathode are proposed. The importance of understanding microbe-cathode interactions, as well as electron transfer mechanisms at the cathode-cell and cell-cell interface to better design dual-function macroporous hollow-fiber cathodes, is critically discussed with insights on how the choice of material is important in facilitating direct electron transfer versus mediated electron transfer.

  20. Dual-Function Electrocatalytic and Macroporous Hollow-Fiber Cathode for Converting Waste Streams to Valuable Resources Using Microbial Electrochemical Systems

    KAUST Repository

    Katuri, Krishna

    2018-04-30

    Dual-function electrocatalytic and macroporous hollow-fiber cathodes are recently proposed as promising advanced material for maximizing the conversion of waste streams such as wastewater and waste CO2 to valuable resources (e.g., clean freshwater, energy, value-added chemicals) in microbial electrochemical systems. The first part of this progress report reviews recent developments in this type of cathode architecture for the simultaneous recovery of clean freshwater and energy from wastewater. Critical insights are provided on suitable materials for fabricating these cathodes, as well as addressing some challenges in the fabrication process with proposed strategies to overcome them. The second and complementary part of the progress report highlights how the unique features of this cathode architecture can solve one of the intrinsic bottlenecks (gas-liquid mass transfer limitation) in the application of microbial electrochemical systems for CO2 reduction to value-added products. Strategies to further improve the availability of CO2 to microbial catalysts on the cathode are proposed. The importance of understanding microbe-cathode interactions, as well as electron transfer mechanisms at the cathode-cell and cell-cell interface to better design dual-function macroporous hollow-fiber cathodes, is critically discussed with insights on how the choice of material is important in facilitating direct electron transfer versus mediated electron transfer.

  1. Observation of radio frequency ring-shaped hollow cathode discharge plasma with MgO and Al electrodes for plasma processing

    International Nuclear Information System (INIS)

    Ohtsu, Yasunori; Matsumoto, Naoki

    2014-01-01

    Various high-density plasma sources have been proposed for plasma processing. Especially, the hollow cathode discharge is one of the powerful ones. In this work, radio-frequency (RF) driven ring-shaped hollow cathode discharges with high secondary-electron emission have been investigated, using an aluminum (Al) cathode, coated or not with magnesium oxide (MgO). The thickness of MgO thin film is approximately 200 nm. The RF discharge voltage for the coated cathode is almost the same as that for the uncoated one, in a wide range of Ar gas pressure, from 5.3 to 53.2 Pa. The results reveal that the plasma density has a peak at an Ar gas pressure of 10.6 Pa for both cathodes. The plasma density for the coated cathode is about 1.5–3 times higher than that for the uncoated one, at various gas pressures. To the contrary, the electron temperature for the coated cathode is lower than temperature obtained with the uncoated cathode, at various gas pressures. Radial profiles of electron saturation current, which is proportional to plasma flux, are also examined for a wide range of gas pressure. Radial profiles of electron temperature at various axial positions are almost uniform for both cathodes so that the diffusion process due to density gradient is dominant for plasma transport. The secondary electrons emitted from the coated cathode contribute to the improvement of the plasma flux radial profile obtained using the uncoated cathode

  2. Hollow-cathode electrode for high-power, high-pressure discharge devices

    Science.gov (United States)

    Chang, J.J.; Alger, T.W.

    1995-08-22

    Several different cold cathode configurations are disclosed for a gas discharge device each having a plurality of grooves of selected spacing, depth and width to improve the emission of electrons in a gas discharge device. Each of the cold cathode configurations can be machined from a single piece of a selected material. Several of the configurations can be assembled with individual elements which is easily seen from the various figures. 8 figs.

  3. Electronic and optical device applications of hollow cathode plasma assisted atomic layer deposition based GaN thin films

    International Nuclear Information System (INIS)

    Bolat, Sami; Tekcan, Burak; Ozgit-Akgun, Cagla; Biyikli, Necmi; Okyay, Ali Kemal

    2015-01-01

    Electronic and optoelectronic devices, namely, thin film transistors (TFTs) and metal–semiconductor–metal (MSM) photodetectors, based on GaN films grown by hollow cathode plasma-assisted atomic layer deposition (PA-ALD) are demonstrated. Resistivity of GaN thin films and metal-GaN contact resistance are investigated as a function of annealing temperature. Effect of the plasma gas and postmetallization annealing on the performances of the TFTs as well as the effect of the annealing on the performance of MSM photodetectors are studied. Dark current to voltage and responsivity behavior of MSM devices are investigated as well. TFTs with the N 2 /H 2 PA-ALD based GaN channels are observed to have improved stability and transfer characteristics with respect to NH 3 PA-ALD based transistors. Dark current of the MSM photodetectors is suppressed strongly after high-temperature annealing in N 2 :H 2 ambient

  4. Extraction of a long-pulsed intense electron beam from a pulsed plasma based on hollow cathode discharge

    International Nuclear Information System (INIS)

    Uramoto, Johshin.

    1977-05-01

    An intense electron beam (up to 1.0 kV, 0.8 kA in 0.8 cm phi) is extracted along a uniform magnetic field with a long decay time (up to 2 msec) from a pulsed high density plasma source which is produced with a fast rise time (< 100 μsec) by a secondary discharge based on a dc hollow cathode discharge. Through a back stream of ionized ions from a beam-extracting anode region where a neutral gas is fed, a space charge limit of the electron beam is so reduced that the beam current is determined by an initially injected electron flux and concentrated in a central aperture of the extracting anode. Moreover, the beam pulse width is much extended by the neutral gas feed into the anode space. (auth.)

  5. Excited argon 1s5 production in micro-hollow cathode discharges for use as potential rare gas laser sources

    Science.gov (United States)

    Peterson, Richard D.; Eshel, Ben; Rice, Christopher A.; Perram, Glen P.

    2018-02-01

    The diode-pumped rare gas laser (DPRGL) has been suggested as a potential high-gain, high-energy laser which requires densities on the order of 1013 cm-3 at pressures around 1 atmosphere for efficient operation. Argon 1s5 number densities have been measured in micro-hollow cathode discharges with electrode gaps of 127 and 254 μm and hole diameters from 100-400 μm. The dependency of the metastable argon (1s5) density on total gas pressure, electrode gap distance and hole diameter were explored. The measured densities were all in the range of 0.5 - 2 × 1013 cm-3 with the 400 μm hole diameters being the lowest.

  6. Kinetic model of a Ne-H2 Penning Recombination Laser operating in the hollow cathode discharge

    International Nuclear Information System (INIS)

    Pramatarov, P.M.; Stefanova, M.S.; Petrov, G.M.

    1995-01-01

    The Penning Recombination Laser (PRL) requires the presence of both a recombination plasma populating the upper laser level (ULL) and a gas component efficiently depopulating the lower laser level (LLL) by Penning reactions. Such requirements are met in the negative glow plasma of a pulsed high voltage Ne-H 2 discharge with a helical hollow cathode. High rates of ionizations followed by recombinations are reached due to the beam component of non-Maxwellian electrons of 1-2 keV energy present in the tail of the electron energy distribution function. The H 2 , on the one hand plays the role of Penning component and on the other hand effectively cools the electrons by rotational and vibrational levels excitation. The latter contributes to the effectiveness of the recombination processes. A kinetic model of the physical processes determining the inversion population on the NeI(2p 1 -1s 2 ) transition (the 585.3 nm line) in a Ne-H 2 PRL operating in a high voltage hollow cathode discharge at intermediate pressures is proposed. About 60 plasma-chemical reactions are considered in the model. These include: two-electron recombination of Ne + ; dissociative recombination of Ne 2 + , NeH + and H 2 + ; ion-ion recombination of Ne + and H - ; Ne and H 2 direct ionization by fast electrons; Ne stepwise ionization; Penning ionization; Ne excitation by fast electrons; Ne stepwise excitation and de-excitation; radiative transitions; electron mixing between Ne excited states; H 2 rotational and vibrational levels excitation; H 2 dissociative attachment; elastic electron collisions with H 2 and Ne. The rate constants for the reactions are either taken from the literature or calculated in this work

  7. [Reparative regeneration of rat skin under influence of hollow cathode lamp (HCL) with manganese and copper line spectrum emission].

    Science.gov (United States)

    Mel'nikova, V I; Izvol'skaia, M S; Voronova, S N; Sharipova, M M; Rukin, E M; Zakharova, L A

    2010-01-01

    Influence of local light exposure by hollow cathode lamp with typical manganese and copper (HCL-Mn, Cu) line emission spectrum on posttraumatic regeneration rate of rat skin has been investigated. We performed the comparative analysis of the morphology and the differentiation ability of rat skin on the 15th and 24th days after full-thickness skin wound had been inflicted on rat dorsums. On the 15th day after injury, the experimental group (daily 30 s exposure for two weeks) showed scab loss, re-epithelialization, and hair regrowth, in contrast to the control rats, where scabs were still observed on the 24th day. Histological analysis revealed that in contrast to the control group the treatment with HCL-Mn, Cu resulted in the increased number of hair follicles and sebaceous glands, the decreased number of blood vessels and horizontal orientation of collagen fibers. The immunohistochemistry for OX-62 revealed that the number of dermal dendritic cells in the experimental groups was maximal on the 15th day, and then decreased to the 24th day after injury. The number of dermal dendritic cells was significantly lower in the control group. The immunohistochemistry for pan-keratins in the control animals revealed a high number of cells expressing different types of keratins, distributed in the main part of the epidermis on the 15th day after surgery, whereas in the experimental group the number of such cells was significantly lower and the cells were concentrated more close to the external part of the epidermis. The number of cells stained for keratin 19 was higher in the experimental group on the 15th day after surgery, whereas this number decreased in this group on the 24th day after surgery as compared to the control group. Thus, typical manganese and copper line spectrum emission emitted by hollow cathode lamp stimulates innate immunity, accelerates restoration of derma, skin epithelium and other skin derivates, and stimulates wound healing in general.

  8. Reactive-environment, hollow cathode sputtering: Basic characteristics and application to Al2O3, doped ZnO, and In2O3:Mo

    International Nuclear Information System (INIS)

    Delahoy, A.E.; Guo, S.Y.; Paduraru, C.; Belkind, A.

    2004-01-01

    A method for thin-film deposition has been studied. The method is based on metal sputtering in a hollow cathode configuration with supply of a reactive gas in the vicinity of the substrate. The working gas and entrained sputtered atoms exit the cathode through an elongated slot. The reactive gas is thereby largely prevented from reaching the target. The basic operation of the cathode was studied using a Cu target and pulsed power excitation. These studies included the dependence of deposition rate on power, pressure, and flow rate, film thickness profiles, and film resistivity as a function of substrate conditions. Modeling was conducted to calculate the gas velocity distribution and pressure inside the cavity. Al 2 O 3 films were prepared in a reactive environment of oxygen by sputtering an Al target. It was demonstrated that only a very small amount of oxygen passing through the cathode will oxidize (poison) the target, whereas large quantities of oxygen supplied externally to the cathode need not affect the target at all. A very stable discharge and ease of Al 2 O 3 formation were realized in this latter mode. The method was applied to the preparation of transparent, conductive films of ZnO doped with either Al or B. High deposition rates were achieved, and, at appropriate oxygen flow rates, low film resistivities. High-mobility In 2 O 3 :Mo transparent conductors were also prepared, with resistivities as low as 1.9x10 -4 Ω cm. Scaling relations for hollow cathodes, and deposition efficiency, and process comparisons between magnetron sputtering and linear, reactive-environment, hollow cathode sputtering are presented

  9. Hollow-cathode lamps as optical frequency standards: the influence of optical imaging on the line-strength ratios

    Science.gov (United States)

    Huke, Philipp; Tal-Or, Lev; Sarmiento, Luis Fernando; Reiners, Ansgar

    2016-07-01

    Hollow cathode discharge lamps (HCLs) have been successfully used in recent years as calibration sources of optical astronomical spectrographs. The numerous narrow metal lines have stable wavelengths, which makes them well suited for m/s calibration accuracy of high-resolution spectrographs, while the buffer-gas lines are less stable and less useful. Accordingly, an important property is the metal-to-gas line-strength ratio (Rmetal/gas). Processes inside the lamp cause the light to be emitted from different regions between the cathode and the anode leaing to the emission of different beams with different values of Rmetal/gas. We used commercially- available HCLs to measure and characterize these beams with respect to their spatial distribution, their angle of propagation relative to the optical axis, and their values of Rmetal/gas. We conclude that a good imaging of an HCL into a fiber-fed spectrograph would consist of an aperture close to its front window in order to filter out the parts of the beam with low Rmetal/gas, and of a lens to collimate the important central beam. We show that Rmetal/gas can be further improved with only minor adjustments of the imaging parameters, and that the imaging scheme that yields the highest Rmetal/gas does not necessarily provide the highest flux.

  10. Three-colour photoionization optogalvanic spectroscopy in U-Ne hollow cathode discharges: observation of even-parity autoionization states of uranium

    International Nuclear Information System (INIS)

    Mandal, P.K.; Seema, A.U.; Das, R.C.; Shah, M.L.; Dev, Vas; Suri, B.M.

    2013-01-01

    Three-colour three-step photoionization spectroscopy of uranium has been performed in a U-Ne hollow cathode discharge tube by temporally resolving three-colour photoionization optogalvanic (PIOG) signal from the normal optogalvanic (OG) signal using three tunable pulsed dye lasers. U-Ne hollow cathode discharge tube has been used as a source of uranium atomic vapour and photoionization detector. Using this technique, photoionization spectra of uranium have been investigated systematically in the energy region 52150-52590 cm -1 , through three different excitation pathways, originating from its ground state, 0 cm -1 ( 5 L 0 6 ). By analyzing the three-colour photoionization spectra sixty new even-parity autoionization resonances of uranium have been identified and their probable total angular momentum (J) values have been assigned according to the J-momentum selection rule. (author)

  11. Density of uranium ions in the 4I0/sub 9/2/ ground state in a hollow-cathode type discharge

    International Nuclear Information System (INIS)

    Pianarosa, P.; Bouchard, P.; Saint-Dizier, J.P.; Gagne, J.M.

    1983-01-01

    A hollow-cathode type discharge cell as generator of uranium ions is investigated. The 4 I 0 /sub 9/2/ ground-state ion density has been obtained by absorption spectroscopy at 5493 and 4244 A. The absorption measurements have been performed using two identical hollow-cathode lamps: one acting as a light source, the other as a reservoir of free ions. Neon and xenon have been used as discharge sustaining gases. In our experimental conditions the measured ion ground-state density is of the order of 10 12 ions cm -3 . Absorption measurements performed at 5915 and 4246 A of U i give a density of the order of 10 12 atoms cm -3 . This latter value is in excellent agreement with a previously measured value obtained by laser-absorption spectroscopy

  12. Deposition of hematite Fe.sub.2./sub.O.sub.3./sub. thin film by DC pulsed magnetron and DC pulsed hollow cathode sputtering system

    Czech Academy of Sciences Publication Activity Database

    Hubička, Zdeněk; Kment, Štěpán; Olejníček, Jiří; Čada, Martin; Kubart, T.; Brunclíková, Michaela; Kšírová, Petra; Adámek, Petr; Remeš, Zdeněk

    2013-01-01

    Roč. 549, Dec (2013), s. 184-191 ISSN 0040-6090 R&D Projects: GA ČR GAP108/12/2104; GA MŠk LH12043 Grant - others:AVČR(CZ) M100101215 Institutional support: RVO:68378271 Keywords : HIPIMS * thin films * hollow cathode Subject RIV: BL - Plasma and Gas Discharge Physics Impact factor: 1.867, year: 2013

  13. Improving the Ar I and II branching ratio calibration method: Monte Carlo simulations of effects from photon scattering/reflecting in hollow cathodes

    Science.gov (United States)

    Lawler, J. E.; Den Hartog, E. A.

    2018-03-01

    The Ar I and II branching ratio calibration method is discussed with the goal of improving the technique. This method of establishing a relative radiometric calibration is important in ongoing research to improve atomic transition probabilities for quantitative spectroscopy in astrophysics and other fields. Specific suggestions are presented along with Monte Carlo simulations of wavelength dependent effects from scattering/reflecting of photons in a hollow cathode.

  14. Observation of even-parity autoionization states of uranium by three-colour photoionization optogalvanic spectroscopy in U–Ne hollow cathode discharges

    International Nuclear Information System (INIS)

    Mandal, P.K.; Seema, A.U.; Das, R.C.; Shah, M.L.; Dev, Vas; Suri, B.M.

    2013-01-01

    Three-colour three-step photoionization spectroscopy of uranium has been performed in a U–Ne hollow cathode discharge tube by temporally resolving three-colour photoionization optogalvanic (PIOG) signal from the normal optogalvanic (OG) signal using three tunable pulsed dye lasers. U–Ne hollow cathode discharge tube has been used as a source of uranium atomic vapours and photoionization detector. Using this technique, photoionization spectra of uranium have been investigated systematically in the energy region 52,150–52,590 cm −1 , through three different excitation pathways, originating from its ground state, 0 cm −1 ( 5 L o 6 ). By analysing the three-colour photoionization spectra sixty new even-parity autoionization resonances of uranium have been identified and their probable total angular momentum (J) values have been assigned according to the J-momentum selection rule. The J-value of five autoionization resonances, which have been observed either through all three excitation pathways or through two different excitation pathways where J-value of the second excited levels differs by two, has been assigned uniquely. -- Highlights: ► Three-colour photoionization optogalvanic spectroscopy of uranium was performed in a U–Ne hollow cathode discharge tube. ► Hollow cathode discharge tube was used as a source of atomic vapour and laser ionisation detector. ► Uranium photoionization spectra were investigated through three different three-colour photoionization schemes. ► Sixty new even-parity autoionization levels of uranium were identified. ► J-value of five autoionization levels was assigned uniquely

  15. Microstructure and corrosion resistance of nitrogen-rich surface layers on AISI 304 stainless steel by rapid nitriding in a hollow cathode discharge

    Science.gov (United States)

    Li, Yang; He, Yongyong; Zhang, Shangzhou; Wang, Wei; Zhu, Yijie

    2018-01-01

    Nitriding treatments have been successfully applied to austenitic stainless steels to improve their hardness and tribological properties. However, at temperatures above 450 °C, conventional plasma nitriding processes decrease the corrosion resistance due to the formation of CrN phases within the modified layer. In this work, AISI 304 austenitic stainless steels were efficiently treated by rapid plasma nitriding at a high temperature of 530 °C in a hollow cathode discharge. The enhanced ionization obtained in the hollow cathode configuration provided a high current density and, consequently, a high temperature could be attained in a short time. The nitrided layers were characterized by X-ray diffraction, scanning electron microscopy, atomic force microscopy, transmission electron microscopy and X-ray photoelectron spectroscopy. The results indicated that the dual-layer structure of the nitrided layer consists of a high-N face-centered cubic structure with a free CrN precipitate outer (top) layer and a nitrogen-expanded austenite S-phase bottom layer. The rapid nitriding-assisted hollow cathode discharge technique permits the use of high temperatures, as high as 530 °C, without promoting degradation in the corrosion resistance of stainless steel.

  16. Studies on laser-assisted Penning ionization by the optogalvanic effect in Ne/Eu hollow cathode discharge.

    Science.gov (United States)

    Saini, V K; Kumar, P; Dixit, S K; Nakhe, S V

    2015-02-01

    Laser-assisted Penning ionization (LAPI) is detected in a Ne/Eu hollow cathode (HC) discharge lamp using the pulsed optogalvanic (OG) method. In the Ne/Eu discharge, doubly ionized europium excited energy levels Eu[4f(7)(P(7/2,5/2)6)] lie within the thermal limit (∼kT) from the laser-excited neon's energy level [2p(5)(P3/202)3p or 2p(8) (in Paschen notation)] lying at 149,848  cm(-1). Therefore, Penning ionization (PI) of europium atoms likely to occur into its highly excited ionic states is investigated. To probe the PI of europium, the temporal profiles of its counterpart neon OG signal are studied as a function of discharge current for the transitions (1s(4)→2p(8)) and (1s(2)→2p(2)), corresponding to 650.65 and 659.89 nm wavelengths, respectively. It is observed that PI of europium alters the overall discharge characteristics significantly and, hence, modifies the temporal profile of the OG signals accordingly. The quasi-resonant ionizing energy transfer collisions between laser-excited Ne 2p(8) atoms and electronically excited europium P(9/2)10 atoms are used to explain the LAPI mechanism. Such LAPI studies carried out in HC discharge could be useful for the discharge of a metal-vapor laser with appropriate Penning mixtures.

  17. Interfacial Reaction Dependent Performance of Hollow Carbon Nanosphere – Sulfur Composite as a Cathode for Li-S Battery

    International Nuclear Information System (INIS)

    Zheng, Jianming; Yan, Pengfei; Gu, Meng; Wagner, Michael J.; Hays, Kevin A.; Chen, Junzheng; Li, Xiaohong; Wang, Chongmin; Zhang, Ji-Guang; Liu, Jun; Xiao, Jie

    2015-01-01

    Lithium-sulfur (Li-S) battery is a promising energy storage system due to its high energy density, cost effectiveness, and environmental friendliness of sulfur. However, there are still a number of technical challenges, such as low Coulombic efficiency and poor long-term cycle life, impeding the commercialization of Li-S battery. The electrochemical performance of Li-S battery is closely related with the interfacial reactions occurring between hosting substrate and active sulfur species, which are poorly conducting at fully oxidized and reduced states. Here, we correlate the relationship between the performance and interfacial reactions in the Li-S battery system, using a hollow carbon nanosphere (HCNS) with highly graphitic character as hosting substrate for sulfur. With an appropriate amount of sulfur loading, HCNS/S composite exhibits excellent electrochemical performance because of the fast interfacial reactions between HCNS and the polysulfides. However, further increase of sulfur loading leads to increased formation of highly resistive insoluble reaction products (Li 2 S 2 /Li 2 S), which limits the reversibility of the interfacial reactions and results in poor electrochemical performances. These findings demonstrate the importance of the interfacial reaction reversibility in the whole electrode system on achieving high capacity and long cycle life of sulfur cathode for Li-S batteries.

  18. Interfacial Reaction Dependent Performance of Hollow Carbon Nanosphere – Sulfur Composite as a Cathode for Li-S Battery

    Energy Technology Data Exchange (ETDEWEB)

    Zheng, Jianming; Yan, Pengfei; Gu, Meng [Pacific Northwest National Laboratory, Richland, WA (United States); Wagner, Michael J.; Hays, Kevin A. [The George Washington University, Washington, DC (United States); Chen, Junzheng; Li, Xiaohong; Wang, Chongmin; Zhang, Ji-Guang; Liu, Jun; Xiao, Jie, E-mail: jie.xiao@pnnl.gov [Pacific Northwest National Laboratory, Richland, WA (United States)

    2015-05-26

    Lithium-sulfur (Li-S) battery is a promising energy storage system due to its high energy density, cost effectiveness, and environmental friendliness of sulfur. However, there are still a number of technical challenges, such as low Coulombic efficiency and poor long-term cycle life, impeding the commercialization of Li-S battery. The electrochemical performance of Li-S battery is closely related with the interfacial reactions occurring between hosting substrate and active sulfur species, which are poorly conducting at fully oxidized and reduced states. Here, we correlate the relationship between the performance and interfacial reactions in the Li-S battery system, using a hollow carbon nanosphere (HCNS) with highly graphitic character as hosting substrate for sulfur. With an appropriate amount of sulfur loading, HCNS/S composite exhibits excellent electrochemical performance because of the fast interfacial reactions between HCNS and the polysulfides. However, further increase of sulfur loading leads to increased formation of highly resistive insoluble reaction products (Li{sub 2}S{sub 2}/Li{sub 2}S), which limits the reversibility of the interfacial reactions and results in poor electrochemical performances. These findings demonstrate the importance of the interfacial reaction reversibility in the whole electrode system on achieving high capacity and long cycle life of sulfur cathode for Li-S batteries.

  19. Building Honeycomb-Like Hollow Microsphere Architecture in a Bubble Template Reaction for High-Performance Lithium-Rich Layered Oxide Cathode Materials.

    Science.gov (United States)

    Chen, Zhaoyong; Yan, Xiaoyan; Xu, Ming; Cao, Kaifeng; Zhu, Huali; Li, Lingjun; Duan, Junfei

    2017-09-13

    In the family of high-performance cathode materials for lithium-ion batteries, lithium-rich layered oxides come out in front because of a high reversible capacity exceeding 250 mAh g -1 . However, the long-term energy retention and high energy densities for lithium-rich layered oxide cathode materials require a stable structure with large surface areas. Here we propose a "bubble template" reaction to build "honeycomb-like" hollow microsphere architecture for a Li 1.2 Mn 0.52 Ni 0.2 Co 0.08 O 2 cathode material. Our material is designed with ca. 8-μm-sized secondary particles with hollow and highly exposed porous structures that promise a large flexible volume to achieve superior structure stability and high rate capability. Our preliminary electrochemical experiments show a high capacity of 287 mAh g -1 at 0.1 C and a capacity retention of 96% after 100 cycles at 1.0 C. Furthermore, the rate capability is superior without any other modifications, reaching 197 mAh g -1 at 3.0 C with a capacity retention of 94% after 100 cycles. This approach may shed light on a new material engineering for high-performance cathode materials.

  20. Solvothermal Synthesis of a Hollow Micro-Sphere LiFePO4/C Composite with a Porous Interior Structure as a Cathode Material for Lithium Ion Batteries

    Science.gov (United States)

    Liu, Yang; Zhang, Jieyu; Li, Ying; Hu, Yemin; Li, Wenxian; Zhu, Mingyuan; Hu, Pengfei; Chou, Shulei; Wang, Guoxiu

    2017-01-01

    To overcome the low lithium ion diffusion and slow electron transfer, a hollow micro sphere LiFePO4/C cathode material with a porous interior structure was synthesized via a solvothermal method by using ethylene glycol (EG) as the solvent medium and cetyltrimethylammonium bromide (CTAB) as the surfactant. In this strategy, the EG solvent inhibits the growth of the crystals and the CTAB surfactant boots the self-assembly of the primary nanoparticles to form hollow spheres. The resultant carbon-coat LiFePO4/C hollow micro-spheres have a ~300 nm thick shell/wall consisting of aggregated nanoparticles and a porous interior. When used as materials for lithium-ion batteries, the hollow micro spherical LiFePO4/C composite exhibits superior discharge capacity (163 mAh g−1 at 0.1 C), good high-rate discharge capacity (118 mAh g−1 at 10 C), and fine cycling stability (99.2% after 200 cycles at 0.1 C). The good electrochemical performances are attributed to a high rate of ionic/electronic conduction and the high structural stability arising from the nanosized primary particles and the micro-sized hollow spherical structure. PMID:29099814

  1. Solvothermal Synthesis of a Hollow Micro-Sphere LiFePO4/C Composite with a Porous Interior Structure as a Cathode Material for Lithium Ion Batteries

    Directory of Open Access Journals (Sweden)

    Yang Liu

    2017-11-01

    Full Text Available To overcome the low lithium ion diffusion and slow electron transfer, a hollow micro sphere LiFePO4/C cathode material with a porous interior structure was synthesized via a solvothermal method by using ethylene glycol (EG as the solvent medium and cetyltrimethylammonium bromide (CTAB as the surfactant. In this strategy, the EG solvent inhibits the growth of the crystals and the CTAB surfactant boots the self-assembly of the primary nanoparticles to form hollow spheres. The resultant carbon-coat LiFePO4/C hollow micro-spheres have a ~300 nm thick shell/wall consisting of aggregated nanoparticles and a porous interior. When used as materials for lithium-ion batteries, the hollow micro spherical LiFePO4/C composite exhibits superior discharge capacity (163 mAh g−1 at 0.1 C, good high-rate discharge capacity (118 mAh g−1 at 10 C, and fine cycling stability (99.2% after 200 cycles at 0.1 C. The good electrochemical performances are attributed to a high rate of ionic/electronic conduction and the high structural stability arising from the nanosized primary particles and the micro-sized hollow spherical structure.

  2. Characterization of hollow cathode fall field strength measured by Doppler-free two-photon optogalvanic spectroscopy via Stark splitting of the 2S level of hydrogen and deuterium

    Energy Technology Data Exchange (ETDEWEB)

    Perez, C; De la Rosa, M I; Gruetzmacher, K, E-mail: concha@opt.uva.e [Universidad de Valladolid, Facultad de Ciencias, 47071 Valladolid (Spain)

    2010-05-01

    Doppler-free two-photon optogalvanic spectroscopy has been applied to measure the strong electric field strength and the cathode fall characteristics of hollow cathode discharges operated in hydrogen and deuterium via the Stark splitting of the 2S level of atomic hydrogen isotopes. In this paper we show similarities and differences in the tendencies of the cathode fall characteristics of hydrogen and deuterium in a wide range of identical discharge parameters.

  3. Characterization of hollow cathode fall field strength measured by Doppler-free two-photon optogalvanic spectroscopy via Stark splitting of the 2S level of hydrogen and deuterium

    International Nuclear Information System (INIS)

    Perez, C; De la Rosa, M I; Gruetzmacher, K

    2010-01-01

    Doppler-free two-photon optogalvanic spectroscopy has been applied to measure the strong electric field strength and the cathode fall characteristics of hollow cathode discharges operated in hydrogen and deuterium via the Stark splitting of the 2S level of atomic hydrogen isotopes. In this paper we show similarities and differences in the tendencies of the cathode fall characteristics of hydrogen and deuterium in a wide range of identical discharge parameters.

  4. Absolute UV and VUV emission in the 110-400 nm region from 13.56 MHz driven hollow slot microplasmas operating in open air

    International Nuclear Information System (INIS)

    Rahman, A; Yalin, A P; Surla, V; Stan, O; Hoshimiya, K; Yu, Z; Littlefield, Eric; Collins, G J

    2004-01-01

    We present absolute optical emission spectra in the 110-400 nm regions from radio-frequency-driven (13.56 MHz) hollow slot microplasmas operating in open air at atmospheric pressure. The term microplasma in our research refers to inter-electrode separation (100-600 μm) only, as electrode lengths are scalable from 1 to 30 cm. This creates an extended slot plasma and an associated afterglow plume as described herein. Spectra are presented for gas flows through the microelectrodes of argon and helium with small admixtures of hydrogen and nitrogen into open air. The spectra are discussed in terms of species origin and magnitude of the dominant emission lines. Atomic O and N lines dominate the 110-200 nm region, whereas, in the 200-400 nm region, NO, N 2 , N 2 + and NH molecular lines are strongest. The role of the N 2 A 3 Σ u state in the open air microplasmas is discussed and the second positive system of molecular nitrogen (N 2 (C 3 Π g -B 3 Π g )), is used to measure the rotational (gas) temperature. Finally, we compare the efficiency and magnitude of light emission from the open air microplasmas with values attainable from commercial sealed mercury lamps in the UVB and UVC regions

  5. [The comparative assessment of the wound-healing effects of the treatment with the use of Bioptron, Minitag, Orion+ apparatuses and hollow cathode lamps (experimental study)].

    Science.gov (United States)

    Sharipova, M M; Voronova, S N; Rukin, E M; Vasilenko, A M

    2011-01-01

    The objective of the present experimental study was the comparative assessment of the wound-healing effects of radiation emitted from Bioptron, Minitag, Orion+ apparatuses and hollow cathode lamps (HCL). The emitters of any type were shown to be equally efficacious in that they accelerated wound epithelization by 30% on the average compared with control. Based on the difference between spectral and power characteristics of different sources of radiation and dynamics of their wound-healing efficacy (including that of two types of HCL), the authors arrived at the conclusion that the further development of the proposed approach to wound healing is a promising line of research in the field of spectral phototherapy.

  6. Diagnostic of a Hollow Cathode Radio-Frequency Plasma Excited in Organosilicon HMDSO, used for Barrier Anti Corrosion Thin Films Deposition

    International Nuclear Information System (INIS)

    Saloum, S.; Naddaf, M.

    2010-01-01

    In this work, remote hollow cathode RF plasma, generated from the monomer hexamethyledisiloxane (HMDSO), as a precursor, and argon as a feed gas, and the plasma mixture HMDSO/O 2 have been studied, as a function of different plasma parameters such as: RF applied power (100-300 W), HMDSO flow rate (2-32 sccm), time deposition (5-20 minutes), and oxygen fraction in HMDSO/O 2 mixture (0-0.9). Plasma diagnostic and prepared thin films characterization have been investigated. (author)

  7. Efficient small molecular organic light emitting diode with graphene cathode covered by a Sm layer with nano-hollows and n-doped by Bphen:Cs2CO3 in the hollows

    Science.gov (United States)

    Yao, Li; Li, Lei; Qin, Laixiang; Ma, Yaoguang; Wang, Wei; Meng, Hu; Jin, Weifeng; Wang, Yilun; Xu, Wanjin; Ran, Guangzhao; You, Liping; Qin, Guogang

    2017-03-01

    Graphene is a favorable candidate for electrodes of organic light emitting diodes (OLEDs). Graphene has quite a high work function of ˜4.5 eV, and has been extensively studied when used as anodes of OLEDs. In order to use graphene as a cathode, the electron injection barrier between the graphene cathode and the electron transport layer has to be low enough. Using 4,7-diphenyl-1,10-phenanthroline (Bphen):Cs2CO3 to n-dope graphene is a very good method, but the electron injection barrier between the n-doped graphene and Bphen:Cs2CO3 is still too high to be ˜1.0 eV. In this work, in order to further reduce the electron injection barrier, a novel method is suggested. On the graphene cathode, a Sm layer with a lot of nano-hollows, and subsequently a layer of Bphen:Cs2CO3, are deposited. The Bphen:Cs2CO3 can n-dope graphene in the nano-hollows, and the Fermi level of the graphene rises. The nano Sm layer is very easily oxidized. Oxygen adsorbed on the surface of graphene may react with Sm to form an O--Sm+ dipole layer. On the areas of the Sm oxide dipole layer without nano-hollows, the electron injection barrier can be further lowered by the dipole layer. Electrons tend to mainly inject through the lower electron barrier where the dipole layer exists. Based on this idea, an effective inverted small molecular OLED with the structure of graphene/1 nm Sm layer with a lot of nano-hollows/Bphen:Cs2CO3/Alq3:C545T/NPB/MoO3/Al is presented. The maximum current efficiency and maximum power efficiency of the OLED with a 1 nm Sm layer are about two and three times of those of the reference OLED without any Sm layer, respectively.

  8. Solvothermal synthesis of monodisperse LiFePO4 micro hollow spheres as high performance cathode material for lithium ion batteries.

    Science.gov (United States)

    Yang, Shiliu; Hu, Mingjun; Xi, Liujiang; Ma, Ruguang; Dong, Yucheng; Chung, C Y

    2013-09-25

    A microspherical, hollow LiFePO4 (LFP) cathode material with polycrystal structure was simply synthesized by a solvothermal method using spherical Li3PO4 as the self-sacrificed template and FeCl2·4H2O as the Fe(2+) source. Scanning electron microscopy (SEM) and transmission electron microscopy (TEM) show that the LFP micro hollow spheres have a quite uniform size of ~1 μm consisting of aggregated nanoparticles. The influences of solvent and Fe(2+) source on the phase and morphology of the final product were chiefly investigated, and a direct ion exchange reaction between spherical Li3PO4 templates and Fe(2+) ions was firstly proposed on the basis of the X-ray powder diffraction (XRD) transformation of the products. The LFP nanoparticles in the micro hollow spheres could finely coat a uniform carbon layer ~3.5 nm by a glucose solution impregnating-drying-sintering process. The electrochemical measurements show that the carbon coated LFP materials could exhibit high charge-discharge capacities of 158, 144, 125, 101, and even 72 mAh g(-1) at 0.1, 1, 5, 20, and 50 C, respectively. It could also maintain 80% of the initial discharge capacity after cycling for 2000 times at 20 C.

  9. The plasma properties and electron emission characteristics of near-zero differential resistance of hollow cathode-based plasma contactors with a discharge chamber

    Energy Technology Data Exchange (ETDEWEB)

    Xie, Kan, E-mail: xiekan@bit.edu.cn [School of Aerospace Engineering, Beijing Institute of Technology, Beijing 100081 (China); Farnell, Casey C.; Williams, John D. [Department of Mechanical Engineering, Colorado State University, Fort Collins, Colorado 80524 (United States)

    2014-08-15

    The formation of electron emission-bias voltage (I-V) characteristics of near-zero differential resistance in the cathodic plasma contactor for bare electrodynamic tether applications, based on a hollow cathode embedded in a ring-cusp ionization stage, is studied. The existence of such an I-V regime is important to achieve low impedance performance without being affected by the space plasma properties for a cathodic plasma contactor. Experimental data on the plasma structure and properties downstream from the ionization stage are presented as functions of the xenon flow rate and the electron emission current. The electrons were emitted from the cathode to the cylindrical vacuum chamber wall (r = 0.9 m) under ≈10{sup −5 }Torr of vacuum pressure. The ring-cusp configuration selected for the plasma contactor created a 125-Gauss axial field near the cathode orifice, along with a large-volume 50-Gauss magnitude pocket in the stage. A baseline ion energy cost of ≈300 eV/ion was measured in the ionization stage when no electrons were emitted to the vacuum chamber wall. In addition, the anode fall growth limited the maximum propellant unitization to below ≈75% in the discharge loss curves for this ion stage. Detailed measurements on the plasma properties were carried out for the no-electron emission and 3 A emission conditions. The experimental data are compared with 1-D models, and the effectiveness of the model is discussed. The four key issues that played important roles in the process of building the near-zero different resistance I-V regime are: a significant amount of ionization by the emission electrons, a decrease in the number of reflected electrons in the plume, the electron-temperature increment, and low initial ion energy at the source outlet.

  10. Destructive physical analysis of hollow cathodes from the Deep Space 1 Flight spare ion engine 30,000 hr life test

    Science.gov (United States)

    Sengupta, Anita

    2005-01-01

    Destructive physical analysis of the discharge and neutralizer hollow cathode assemblies from the Deep Space 1 Flight Spare 30,000 Hr life test was performed to characterize physical and chemical evidence of operationally induced effects after 30,372 hours of operation with beam extraction. Post-test inspection of the discharge-cathode assembly was subdivided into detailed analyses at the subcomponent level. Detailed materials analysis and optical inspection of the insert, orifice plate, cathode tube, heater, keeper assembly, insulator, and low-voltage propellant isolator were performed. Energy dispersive X-ray (EDX) and scanning electron microscopy (SEW analyses were used to determine the extent and composition of regions of net deposition and erosion of both the discharge and neutralizer inserts. A comparative approach with an un-operated 4:1:1 insert was used to determine the extent of impregnate material depletion as a function of depth from the ID surface and axial position from the orifice plate. Analysis results are compared and contrasted with those obtained from similar analyses on components from shorter term tests, and provide insight regarding the prospect for successful longer-term operation consistent with SOA ion engine program life objectives at NASA.

  11. An ingenious design of lamellar Li1.2Mn0.54Ni0.13Co0.13O2 hollow nanosphere cathode for advanced lithium-ion batteries

    International Nuclear Information System (INIS)

    Zhang, Yao; Zhang, Wansen; Shen, Shuiyun; Yan, Xiaohui; Wu, Aiming; Wu, Ruofei; Zhang, Junliang

    2017-01-01

    Highlights: •Lamellar Li 1.2 Mn 0.54 Ni 0.13 Co 0.13 O 2 hollow nanospheres serve as a cathode for LIBs. •Unique lamella and hollow structures benefit the enhanced electrochemical performance. •Lamellar shells can provide a short lithium-ion diffusion pathway. •The sufficient void space can accommodate volumetric expansion and contraction. -- Abstract: Although very appealing in developing hollow structured lithium-rich layered transition-metal oxides as cathodes for lithium-ion batteries (LIBs), a great challenge lies in controlling the growth of transition metal elements with desired molar ratios while maintaining intact hollow structures during synthesis. Herein, we propose a scalable strategy to successfully synthesize novel lamellar Li 1.2 Mn 0.54 Ni 0.13 Co 0.13 O 2 hollow (L-LMOH) nanosphere cathode for advanced lithium-ion batteries (LIBs). It is proved that the employment of sulfonated polystyrene (SPS) gel nanospheres as the template plays a key role in the formation of flower-like SPS@ Ni-Co-Mn-precursor nanospheres with desired molar ratios, and a subsequently delicate control in the heating rate leads to the intact L-LMOH nanospheres. It is demonstrated that the use of L-LMOH nanosphere cathode not only delivers outstanding reversible discharge capacities of 281.7 mAh g −1 at a current density of 20 mA g −1 and 136.6 mAh g −1 at 2000 mA g −1 , but also possess superior cycling stability with a capacity reservation of 80% at 2000 mA g −1 after 200 continuous cycles. It is well analyzed that the ingenious design of both unique lamella and hollow architectures synergistically benefits the significantly enhanced rate capability and cycling stability.

  12. [Atomic/ionic fluorescence in microwave plasma torch discharge with excitation of high current and microsecond pulsed hollow cathode lamp: Ca atomic/ionic fluorescence spectrometry].

    Science.gov (United States)

    Gong, Zhen-bin; Liang, Feng; Yang, Peng-yuan; Jin, Qin-han; Huang, Ben-li

    2002-02-01

    A system of atomic and ionic fluorescence spectrometry in microwave plasma torch (MPT) discharge excited by high current microsecond pulsed hollow cathode lamp (HCMP HCL) has been developed. The operation conditions for Ca atomic and ionic fluorescence spectrometry have been optimized. Compared with atomic fluorescence spectrometry (AFS) in argon microwave induced plasma (MIP) and MPT with the excitation of direct current and conventional pulsed HCL, the system with HCMP HCL excitation can improve AFS and ionic fluorescence spectrometry (IFS) detection limits in MPT atomizer and ionizer. Detection limits (3 sigma) with HCMP HCL-MPT-AFS/IFS are 10.1 ng.mL-1 for Ca I 422.7 nm, 14.6 ng.mL-1 for Ca II 393.4 nm, and 37.4 ng.mL-1 for Ca II 396.8 nm, respectively.

  13. [Atomic/ionic fluorescence in microwave plasma torch discharge excited by high current microsecond pulsed hollow cathode lamp-europium atomic/ionic fluorescence spectrometry].

    Science.gov (United States)

    Gong, Z; Liang, F; Yang, P; Jin, Q; Huang, B

    1999-06-01

    Eu atomic and ionic fluorescence spectrometry in microwave plasma torch discharge excited by high current microsecond pulsed hollow cathode lamp (HCMP HCL-MPT AFS/IFS) was studied. Operating conditions were optimized. The best detection limits for AFS and IFS obtained with a desolvated ultrasonic nebulization system were 42.0 ng/mL for Eu I 462.7 nm and 21.8 ng/mL for Eu II 381.97 nm, respectively, both were better than those given by the instruction manual of a Baird ICP AFS-2000 spectrometer using pneumatic concentric nebulizer with desolvation for AFS, but were significantly higher than those obtained by using the Baird spectrometer with a mini-monochromator and a ultrasonic nebulzer system.

  14. Deposition of thin film of titanium on ceramic substrate using the discharge for hollow cathode for Al2O3/Al2O3 indirect brazing

    Directory of Open Access Journals (Sweden)

    Mary Roberta Meira Marinho

    2009-01-01

    Full Text Available Thin films of titanium were deposited onto Al2O3 substrate by hollow cathode discharge method for the formation of a ceramic-ceramic joint using indirect brazing method. An advantage of using this technique is that a relatively small amount of titanium is required for the metallization of the ceramic surface when compared with other conventional methods. Rapidly solidified brazing filler of Cu49Ag45Ce6 in the form of ribbons was used. The thickness of deposited titanium layer and the brazing temperature/time were varied. The quality of the brazed joint was evaluated through the three point bending flexural tests. The brazed joints presented high flexural resistance values up to 176 MPa showing the efficiency of the technique.

  15. Generation of uniform low-temperature plasma in a pulsed non-self-sustained glow discharge with a large-area hollow cathode

    Energy Technology Data Exchange (ETDEWEB)

    Akhmadeev, Yu. H.; Denisov, V. V., E-mail: volodyadenisov@yandex.ru; Koval, N. N.; Kovalsky, S. S.; Lopatin, I. V.; Schanin, P. M.; Yakovlev, V. V. [Russian Academy of Sciences, Institute of High-Current Electronics, Siberian Branch (Russian Federation)

    2017-01-15

    Generation of plasma in a pulsed non-self-sustained glow discharge with a hollow cathode with an area of ≥2 m{sup 2} at gas pressures of 0.4–1 Pa was studied experimentally. At an auxiliary arc-discharge current of 100 A and a main discharge voltage of 240 V, a pulse-periodic glow discharge with a current amplitude of 370 A, pulse duration of 340 μs, and repetition rate of 1 kHz was obtained. The possibility of creating a uniform gas-discharge plasma with a density of up to 10{sup 12} cm{sup −3} and an electron temperature of 1 eV in a volume of >0.2 m{sup 3} was demonstrated. Such plasma can be efficiently used to treat material surfaces and generate pulsed ion beams with a current density of up to 15 mA/cm{sup 2}.

  16. Difference-frequency laser spectroscopy of molecular ions with a hollow-cathode cell: extended analysis of the ν1 band of H2D+

    International Nuclear Information System (INIS)

    Amano, T.

    1985-01-01

    A cooled hollow-cathode cell was used for observation of the infrared spectra of positive ions in the 3-μm region with a difference-frequency laser as a radiation source. About an order-of-magnitude enhancement of the signal intensity was attained, compared with the similar signals obtained with our previous glow-discharge cell. Ten more weaker lines of the ν 1 fundamental band of H 2 D + , which could not be observed in our previous experiment [J. Chem. Phys. 81, 2869 (1984)] were measured. Improved molecular constants were obtained from a least-squares fit including the infrared lines and the two millimeter-and submillimeter-wave lines in the ground state

  17. Graphene-coated hollow fiber membrane as the cathode in anaerobic electrochemical membrane bioreactors – Effect of configuration and applied voltage on performance and membrane fouling

    KAUST Repository

    Werner, Craig M.; Katuri, Krishna; Rao, Hari Ananda; Chen, Wei; Lai, Zhiping; Logan, Bruce E.; Amy, Gary L.; Saikaly, Pascal

    2015-01-01

    Electrically conductive, graphene-coated hollow-fiber porous membranes were used as cathodes in anaerobic electrochemical membrane bioreactors (AnEMBRs) operated at different applied voltages (0.7 V and 0.9 V) using a new rectangular reactor configuration, compared to a previous tubular design (0.7 V). The onset of biofouling was delayed and minimized in rectangular reactors operated at 0.9 V, compared to those at 0.7 V due to higher rates of hydrogen production. Maximum transmembrane pressures for the rectangular reactor were only 0.10 bar (0.7 V) or 0.05 bar (0.9 V) after 56 days of operation, compared to 0.46 bar (0.7 V) for the tubular reactor after 52 days. The thickness of the membrane biofouling layer was approximately 0.4 µm for rectangular reactors and 4 µm for the tubular reactor. Higher permeate quality (TSS = 0.05 mg/L) was achieved in the rectangular AnEMBR than the tubular AnEMBR (TSS = 17 mg/L), likely due to higher current densities that minimized the accumulation of cells in suspension. These results show that the new rectangular reactor design, which had increased rates of hydrogen production, successfully delayed the onset of cathode biofouling and improved reactor performance.

  18. Graphene-coated hollow fiber membrane as the cathode in anaerobic electrochemical membrane bioreactors – Effect of configuration and applied voltage on performance and membrane fouling

    KAUST Repository

    Werner, Craig M.

    2015-12-22

    Electrically conductive, graphene-coated hollow-fiber porous membranes were used as cathodes in anaerobic electrochemical membrane bioreactors (AnEMBRs) operated at different applied voltages (0.7 V and 0.9 V) using a new rectangular reactor configuration, compared to a previous tubular design (0.7 V). The onset of biofouling was delayed and minimized in rectangular reactors operated at 0.9 V, compared to those at 0.7 V due to higher rates of hydrogen production. Maximum transmembrane pressures for the rectangular reactor were only 0.10 bar (0.7 V) or 0.05 bar (0.9 V) after 56 days of operation, compared to 0.46 bar (0.7 V) for the tubular reactor after 52 days. The thickness of the membrane biofouling layer was approximately 0.4 µm for rectangular reactors and 4 µm for the tubular reactor. Higher permeate quality (TSS = 0.05 mg/L) was achieved in the rectangular AnEMBR than the tubular AnEMBR (TSS = 17 mg/L), likely due to higher current densities that minimized the accumulation of cells in suspension. These results show that the new rectangular reactor design, which had increased rates of hydrogen production, successfully delayed the onset of cathode biofouling and improved reactor performance.

  19. High-energy lithium-ion hybrid supercapacitors composed of hierarchical urchin-like WO3/C anodes and MOF-derived polyhedral hollow carbon cathodes.

    Science.gov (United States)

    Xu, Juan; Li, Yuanyuan; Wang, Lei; Cai, Qifa; Li, Qingwei; Gao, Biao; Zhang, Xuming; Huo, Kaifu; Chu, Paul K

    2016-09-22

    A lithium-ion hybrid supercapacitor (Li-HSC) comprising a Li-ion battery type anode and an electrochemical double layer capacitance (EDLC) type cathode has attracted much interest because it accomplishes a large energy density without compromising the power density. In this work, hierarchical carbon coated WO 3 (WO 3 /C) with a unique mesoporous structure and metal-organic framework derived nitrogen-doped carbon hollow polyhedra (MOF-NC) are prepared and adopted as the anode and the cathode for Li-HSCs. The hierarchical mesoporous WO 3 /C microspheres assembled by radially oriented WO 3 /C nanorods along the (001) plane enable effective Li + insertion, thus exhibit high capacity, excellent rate performance and a long cycling life due to their high Li + conductivity, electronic conductivity and structural robustness. The WO 3 /C structure shows a reversible specific capacity of 508 mA h g -1 at a 0.1 C rate (1 C = 696 mA h g -1 ) after 160 discharging-charging cycles with excellent rate capability. The MOF-NC achieved the specific capacity of 269.9 F g -1 at a current density of 0.2 A g -1 . At a high current density of 6 A g -1 , 92.4% of the initial capacity could be retained after 2000 discharging-charging cycles, suggesting excellent cycle stability. The Li-HSC comprising a WO 3 /C anode and a MOF-NC cathode boasts a large energy density of 159.97 W h kg -1 at a power density of 173.6 W kg -1 and 88.3% of the capacity is retained at a current density of 5 A g -1 after 3000 charging-discharging cycles, which are better than those previously reported for Li-HSCs. The high energy and power densities of the Li-HSCs of WO 3 /C//MOF-NC render large potential in energy storage.

  20. Investigation of the effect of Hollow Cathode in a Grimm-type source (Ar) on the excitation processes using Fe samples

    International Nuclear Information System (INIS)

    Weinstein, V.; Steers, E.B.M.

    2009-01-01

    Complete text of publication follows. Analytical spectroscopic applications using a Grimm Glow Discharge source sometimes require an increased sensitivity and therefore a higher signal to background ratio, which can be reached by using hollow cathode (HC) instead of plane samples. At the beginning of the 20 th century, intensity enhancements of emission lines using HC were observed and explained by longer residence time of sample atoms and consequently more collisional excitation. Later a HC was used with a Grimm source, to achieve higher sensitivity for lines of minor constituents. Recently the HC effect was further investigated for several metallic samples with a commercial GD-OES instrument (T.Gusarova., J. Anal. At. Spectrom., 2009., DOI: 10.1039/b814977a) for improvement of the signal to background ratio (SBR). The intensities and SBR from HC and plane cathode were compared, but only one or two lines could be observed for each element in the sample. The line intensities using plane and HC samples depend on the excitation processes occurring in the two cases. To make conclusions about the excitation mechanism differences, a large number of lines should be examined. Therefore we have recorded spectra over a wide wavelength range (approx. 200-600 nm) using a Fourier Transform Spectrometer (FTS), which allows simultaneous recording of spectra with a very high resolution. The 15 mm deep Fe HC sample and Fe plane cathode sample were analysed using argon as the carrier gas. The comparison of the data was made by calculating the ratio of intensities obtained from the HC sample to intensities of the plane cathode sample and plotting this against the excitation energy of Fe I, Fe II and Ar I, Ar II emission lines. Such plots link the intensity differences with the upper levels of the transitions and so help to clarify the relative importance of excitation processes. The experiments were also carried out at different currents, therefore the effect of the current on

  1. Electrostatic/magnetic ion acceleration through a slowly diverging magnetic nozzle between a ring anode and an on-axis hollow cathode

    Directory of Open Access Journals (Sweden)

    A. Sasoh

    2017-06-01

    Full Text Available Ion acceleration through a slowly diverging magnetic nozzle between a ring anode and a hollow cathode set on the axis of symmetry has been realized. Xenon was supplied as the propellant gas from an annular slit along the inner surface of the ring anode so that it was ionized near the anode, and the applied electric potential was efficiently transformed to an ion kinetic energy. As an electrostatic thruster, within the examined operation conditions, the thrust, F, almost scaled with the propellant mass flow rate; the discharge current, Jd, increased with the discharge voltage, Vd. An important characteristic was that the thrust also exhibited electromagnetic acceleration performance, i.e., the so-called “swirl acceleration,” in which F≅JdBRa ∕2, where B and Ra were a magnetic field and an anode inner radius, respectively. Such a unique thruster performance combining both electrostatic and electromagnetic accelerations is expected to be useful as another option for in-space electric propulsion in its broad functional diversity.

  2. Optical constants of silicon-like (Si:Ox:Cy:Hz) thin films deposited on quartz using hexamethyldisiloxane in a remote RF hollow cathode discharge plasma

    International Nuclear Information System (INIS)

    Saloum, S.; Naddaf, M.

    2008-01-01

    Deposition of amorphous silicon-like (Si:O x :C y :H z ) thin films in a remote RF hollow cathode discharge plasma using Hexamethyldisoloxane as monomer and Ar as feed gas; has been investigated for films optical constants and plasma diagnostic as a function of RF power (100-300 W) and precursor flow rate (1-10 sccm). Plasma diagnostic has been performed using optical emission spectroscopy (OES). The optical constants (refractive index, extinction coefficient and dielectric constant) have been obtained by reflection/transmission measurements in the range 300-700 nm. It is found that the refractive index increases from 1.92 to 1.97 with increasing power from 100 to 300 W, and from 1.70 to 1.92 with increasing precursor flow rate from 1 to 10 sccm. The optical energy-band gap E g and the optical-absorption tail ΔE have been estimated from optical absorption spectra, it is found that E g decreases from 3.28 eV to 3.14 eV with power increase from 100 to 300 W, and from 3.54 eV to 3.28 eV with precursor flow rate increase from 1 to 10 sccm. ΔE is found to increase with applied RF power and precursor flow rate increase. The dependence of optical constants on deposition parameters has been correlated to plasma OES. (author)

  3. High-Rate and Long-Term Cycle Stability of Li-S Batteries Enabled by Li2S/TiO2-Impregnated Hollow Carbon Nanofiber Cathodes.

    Science.gov (United States)

    Wang, Xinran; Bi, Xuanxuan; Wang, Shaona; Zhang, Yi; Du, Hao; Lu, Jun

    2018-05-16

    The high theoretical energy density of lithium-sulfur (Li-S) batteries makes them an alternative battery technology to lithium ion batteries. However, Li-S batteries suffer from low sulfur loading, poor charge transport, and dissolution of lithium polysulfide. In our study, we use the lithiated S, Li 2 S, as the cathode material, coupled with electrospun TiO 2 -impregnated hollow carbon nanofibers (TiO 2 -HCFs), which serve as the conductive agent and protective barrier for Li 2 S in Li-S batteries. TiO 2 -HCFs provide much improved electron/ionic conductivity and serve as a physical barrier, which prevents the dissolution of lithium polysulfides. The Li 2 S/TiO 2 -HCF composite delivers a discharge capacity of 851 mA h g Li 2 S -1 at 0.1C and the bilayer TiO 2 -HCFs/Li 2 S/TiO 2 -HCF composite delivers a high specific capacity of 400 mA h g Li 2 S -1 at 5C.

  4. Electron beam produced in a transient hollow cathode discharge: beam electron distribution function, X-ray emission and solid target ablation

    International Nuclear Information System (INIS)

    Nistor, Magdalena

    2000-01-01

    This research thesis aims at a better knowledge of phenomena occurring during transient hollow cathode discharges. The author first recalls the characteristics of such a discharge which make it different from conventional pseudo-spark discharges. The objective is to characterise the electron beam produced within the discharge, and the phenomena associated with its interaction with a solid or gaseous target, leading to the production of an X ray or visible radiation. Thus, the author reports the measurement (by magnetic deflection) of the whole time-averaged electronic distribution function. Such a knowledge is essential for a better use of the electron beam in applications such as X-ray source or material ablation. As high repetition frequency pulse X ray sources are very interesting tools, he reports the development and characterisation of Bremsstrahlung X rays during a beam-target interaction. He finally addresses the implementation of a spectroscopic diagnosis for the filamentary plasma and the ablation of a solid target by the beam [fr

  5. Effects of spray parameters on the microstructure and property of Al2O3 coatings sprayed by a low power plasma torch with a novel hollow cathode

    International Nuclear Information System (INIS)

    Li Changjiu; Sun Bo

    2004-01-01

    Al 2 O 3 coating is deposited using a low power plasma torch with a novel hollow cathode through axial powder injection under a plasma power up to several kilowatts. The effects of the main processing parameters including plasma arc power, operating gas flow and spray distance on particle velocity during spraying, and the microstructure and property of the coating are investigated. The microstructure of the Al 2 O 3 coating is examined using optical microscopy and X-ray diffraction analysis. The property of the coating is characterized by dry rubber wheel abrasive wear test. The velocity of in-flight particle is measured using a velocity/temperature measurement system for spray particle based on thermal radiation from the particle. The dependency of the microstructure and property of the coating on spray particle conditions are examined by comparing the particle velocity, and microstructure and abrasive wear weight loss of subsequent coating deposited by low power plasma spray with those of the coating by conventional plasma spray at a power one order higher. X-ray diffraction analysis of the coating revealed that Al 2 O 3 particles during low power plasma spraying reach to sufficiently melting state prior to impact on the substrate with a velocity comparable to that in conventional plasma spraying. The experiment results have shown that processing parameters have significant influence on the particle conditions and performance of deposited Al 2 O 3 coating. The coating of comparable microstructure and properties to that deposited by conventional plasma spray can be produced under a power one order lower. From the present study, it can be suggested that a comparable coating can be produced despite plasma power level if the comparable particle velocity and molten state are achieved

  6. Study of the use of an electric discharge for hollow cathodes used as optical excitation sources in the spectrographic measurement of fluorine in thorium, uranium and plutonium; Etude de l'utilisation de la decharge electrique en cathode creuse comme source d'excitation optique pour le dosage spectrographique du fluor dans le thorium, l'uranium et le plutonium

    Energy Technology Data Exchange (ETDEWEB)

    Bufpereau, M; Crehange, G; Poublan, J [Commissariat a l' Energie Atomique, Saclay (France). Centre d' Etudes Nucleaires

    1964-07-01

    Previous works and phenomena concerned with a hollow cathode excitation are reviewed. Experiments aimed specially on the determination of the best conditions for an analysis of fluorine in oxides-metals and solutions. In that purpose, several factors have been pointed out. One started some researches about others elements that fluorine. Carrying fluorine into discharge and excitation have been more specially studied. A quantitative analysis method is given. The analysis limit is 45 ppm about but the detection limit is 5 ppm about. As a conclusion, various ways for optical excitation of fluorine are reviewed as other analytical possibilities a hollow cathode discharge offers. (authors) [French] On rappelle les travaux effectues jusqu'alors ainsi que les phenomenes mis en jeu dans l'excitation cathode creuse. Les experiences effectuees ont eu pour but essentiel la determination des conditions optima du dosage du fluor dans les oxydes, metaux et solutions. Pour cela de nombreux facteurs ont ete mis en evidence. Certaines etudes concernant d'autres elements que le fluor ont ete amorcees. Le passage du fluor dans la decharge et son excitation ont ete plus particulierement etudies. Une methode d'analyse quantitative est degagee, la limite de dosage est de l'ordre de 45 ppm, la limite de detection de 5 ppm. En conclusion, on passe en revue les differentes methodes d'excitation optique du fluor ainsi que les autres possibilites analytiques que peut offrir la cathode creuse. (auteurs)

  7. Synthesis and characterization hollow spherical La0.7Sr0.2Ca0.1Co0.9Fe0.1O3–δ (LSCCT for cathode of solid oxide fuel cell (SOFC

    Directory of Open Access Journals (Sweden)

    H. H. Yu

    2016-10-01

    Full Text Available Hollow spheres structures of La0.7Sr0.2Ca0.1Co0.9Fe0.1O3–δ (LSCCT have been synthesized via hydrothermal method using carbon spheres as template. The structure and electrical conductivity of obtained samples are characterized by X-ray diffraction (XRD, scanning electron microscope (SEM, transmission electron microscope (TEM and direct current (DC four-probe method respectively. The results show that hollow spheres structures of LSCCT with the mean particle size of 0,9 - 1,2 μm is single perovskite. The electrical conductivity of the samples is higher than 100 S/cm from 600 to 800 ℃ and can meet the demand of the electrical properties for the cathode materials.

  8. Comparison of trimethylgallium and triethylgallium as “Ga” source materials for the growth of ultrathin GaN films on Si (100) substrates via hollow-cathode plasma-assisted atomic layer deposition

    International Nuclear Information System (INIS)

    Alevli, Mustafa; Haider, Ali; Kizir, Seda; Leghari, Shahid A.; Biyikli, Necmi

    2016-01-01

    GaN films grown by hollow cathode plasma-assisted atomic layer deposition using trimethylgallium (TMG) and triethylgallium (TEG) as gallium precursors are compared. Optimized and saturated TMG/TEG pulse widths were used in order to study the effect of group-III precursors. The films were characterized by grazing incidence x-ray diffraction, atomic force microscopy, x-ray photoelectron spectroscopy, and spectroscopic ellipsometry. Refractive index follows the same trend of crystalline quality, mean grain, and crystallite sizes. GaN layers grown using TMG precursor exhibited improved structural and optical properties when compared to GaN films grown with TEG precursor

  9. Comparison of trimethylgallium and triethylgallium as “Ga” source materials for the growth of ultrathin GaN films on Si (100) substrates via hollow-cathode plasma-assisted atomic layer deposition

    Energy Technology Data Exchange (ETDEWEB)

    Alevli, Mustafa, E-mail: mustafaalevli@marmara.edu.tr [Department of Physics, Marmara University, Göztepe Kadıköy, 34722 İstanbul (Turkey); Haider, Ali; Kizir, Seda; Leghari, Shahid A.; Biyikli, Necmi, E-mail: biyikli@unam.bilkent.edu.tr [Institute of Materials Science and Nanotechnology, Bilkent University, Bilkent, 06800 Ankara, Turkey and National Nanotechnology Research Center (UNAM), Bilkent University, Bilkent, 06800 Ankara (Turkey)

    2016-01-15

    GaN films grown by hollow cathode plasma-assisted atomic layer deposition using trimethylgallium (TMG) and triethylgallium (TEG) as gallium precursors are compared. Optimized and saturated TMG/TEG pulse widths were used in order to study the effect of group-III precursors. The films were characterized by grazing incidence x-ray diffraction, atomic force microscopy, x-ray photoelectron spectroscopy, and spectroscopic ellipsometry. Refractive index follows the same trend of crystalline quality, mean grain, and crystallite sizes. GaN layers grown using TMG precursor exhibited improved structural and optical properties when compared to GaN films grown with TEG precursor.

  10. Metal-Organic Framework-Derived Reduced Graphene Oxide-Supported ZnO/ZnCo2O4/C Hollow Nanocages as Cathode Catalysts for Aluminum-O2 Batteries.

    Science.gov (United States)

    Liu, Yisi; Jiang, Hao; Hao, Jiayu; Liu, Yulong; Shen, Haibo; Li, Wenzhang; Li, Jie

    2017-09-20

    Aluminum-air battery is a promising candidate for large-scale energy applications because of its low cost and high energy density. Remarkably, tremendous efforts have been concentrated on developing efficient and stable cathode electrocatalysts toward the oxygen reduction reaction. In this work, a hydrothermal-calcination approach was utilized to prepare novel reduced graphene oxide (rGO)-supported hollow ZnO/ZnCo 2 O 4 nanoparticle-embedded carbon nanocages (ZnO/ZnCo 2 O 4 /C@rGO) using a zeolitic imidazolate framework (ZIF-67)/graphene oxide/zinc nitrate composite as the precursor. The ZnO/ZnCo 2 O 4 /C@rGO hybrid exhibits remarkable electrocatalytic performance for oxygen reduction reaction under alkaline conditions and superior stability and methanol tolerance to those of the commercial Pt/C catalyst. Furthermore, novel and simple Al-air coin cells were first fabricated using the hybrid materials as cathode catalysts under ambient air conditions to further investigate their catalytic performance. The coin cell with the ZnO/ZnCo 2 O 4 /C@rGO cathode catalyst displays a higher open circuit voltage and discharge voltage and more sluggish potential drop than those of the cell with the ZnO/ZnCo 2 O 4 /C cathode catalyst, which confirms that rGO can enhance the electrocatalytic activity and stability of the catalyst system. The excellent electrocatalytic performance of the ZnO/ZnCo 2 O 4 /C@rGO hybrid is attributed to the prominent conductivity and high specific surface area resulting from rGO, the more accessible catalytic active sites induced by the unique porous hollow nanocage structure, and synergic covalent coupling between rGO sheets and ZnO/ZnCo 2 O 4 /C nanocages.

  11. Hierarchical Li1.2Mn0.54Ni0.13Co0.13O2 hollow spherical as cathode material for Li-ion battery

    Science.gov (United States)

    Zhang, Yu; Zhu, Tianjiao; Lin, Liu; Yuan, Mengwei; Li, Huifeng; Sun, Genban; Ma, Shulan

    2017-11-01

    Lithium-rich manganese-based layered materials have been considered as the most promising cathode materials for future high-energy-density lithium-ion batteries. However, a great loss of irreversible capacity at the initial cycle, poor cycle stability, and rate performance severely restrict its application. Herein, we develop a new strategy to synthesize hierarchical hollow Li1.2Mn0.54Ni0.13Co0.13O2 microspheres using sucrose and cetyltrimethylammonium bromide as a soft template combined with hydrothermal assisted homogeneous precipitation method. The hollow microspheres are assembled by the primary particles with the size of 50 nm. As a result, the as-prepared material exhibits high reversible capacity, good cycling stability, and excellent rate property. It delivers a high initial discharge capacity of 305.9 mAh g-1 at 28 mA g-1 with coulombic efficiency of 80%. Even at high current density of 560 mA g-1, the sample also shows a stable discharge capacity of 215 mAh g-1. The enhanced electrochemical properties are attributed to the stable hierarchical hollow sphere structure and the appropriate contact area between electrode and electrolyte, thus effectively improve the lithium-ion intercalation and deintercalation kinetics. [Figure not available: see fulltext.

  12. Direct fabrication of metal-free hollow graphene balls with a self-supporting structure as efficient cathode catalysts of fuel cell

    International Nuclear Information System (INIS)

    Lu, Yanqi; Liu, Mingda; Nie, Huagui; Gu, Cancan; Liu, Ming; Yang, Zhi; Yang, Keqin; Chen, Xi’an; Huang, Shaoming

    2016-01-01

    Despite the good progress in developing carbon catalysts for oxygen reduction reaction (ORR), the current metal-free carbon catalysts are still far from satisfactory for large-scale applications of fuel cell. Developing hollow graphene balls with a self-supporting structure is considered to be an ideal method to inhibit graphene stacking and improve their catalytic performance. Herein, we fabricated metal-free hollow graphene balls with a self-supporting structure, through using a new strategy that involves direct metal-free catalytic growth from assembly of SiO_2 spheres. To our knowledge, although much researches involving the synthesis of graphene balls have been reported, investigations into the direct metal-free catalytic growth of hollow graphene balls are rare. Furthermore, the electrocatalytic performance shows that the resulting hollow graphene balls have significantly high catalytic activity. More importantly, such catalysts also possess much improved stability and better methanol tolerance in alkaline media during the ORR compared with commercial Pt/C catalysts. The outstanding performances coupled with an easy and inexpensive preparing method indicated the great potential of the hollow graphene balls with a self-supporting structure in large-scale applications of fuel cell.Graphical AbstractHollow graphene balls with a self-supporting structure have been successfully fabricated, through using a new strategy that involves direct metal-free catalytic growth from 3D assembly of SiO_2 spheres. The hollow graphene balls can exhibit a high catalytic activity, long-term stability, and an excellent methanol tolerance for the oxygen reduction reaction

  13. Direct fabrication of metal-free hollow graphene balls with a self-supporting structure as efficient cathode catalysts of fuel cell

    Energy Technology Data Exchange (ETDEWEB)

    Lu, Yanqi; Liu, Mingda; Nie, Huagui, E-mail: huaguinie@126.com; Gu, Cancan; Liu, Ming; Yang, Zhi, E-mail: yang201079@126.com; Yang, Keqin; Chen, Xi’an; Huang, Shaoming, E-mail: smhuang@wzu.edu.cn [Wenzhou University, Nanomaterials and Chemistry Key Laboratory (China)

    2016-06-15

    Despite the good progress in developing carbon catalysts for oxygen reduction reaction (ORR), the current metal-free carbon catalysts are still far from satisfactory for large-scale applications of fuel cell. Developing hollow graphene balls with a self-supporting structure is considered to be an ideal method to inhibit graphene stacking and improve their catalytic performance. Herein, we fabricated metal-free hollow graphene balls with a self-supporting structure, through using a new strategy that involves direct metal-free catalytic growth from assembly of SiO{sub 2} spheres. To our knowledge, although much researches involving the synthesis of graphene balls have been reported, investigations into the direct metal-free catalytic growth of hollow graphene balls are rare. Furthermore, the electrocatalytic performance shows that the resulting hollow graphene balls have significantly high catalytic activity. More importantly, such catalysts also possess much improved stability and better methanol tolerance in alkaline media during the ORR compared with commercial Pt/C catalysts. The outstanding performances coupled with an easy and inexpensive preparing method indicated the great potential of the hollow graphene balls with a self-supporting structure in large-scale applications of fuel cell.Graphical AbstractHollow graphene balls with a self-supporting structure have been successfully fabricated, through using a new strategy that involves direct metal-free catalytic growth from 3D assembly of SiO{sub 2} spheres. The hollow graphene balls can exhibit a high catalytic activity, long-term stability, and an excellent methanol tolerance for the oxygen reduction reaction.

  14. Synthesis of carbon-coated Na2MnPO4F hollow spheres as a potential cathode material for Na-ion batteries

    Science.gov (United States)

    Wu, Ling; Hu, Yong; Zhang, Xiaoping; Liu, Jiequn; Zhu, Xing; Zhong, Shengkui

    2018-01-01

    Hollow sphere structure Na2MnPO4F/C composite is synthesized through spray drying, following in-situ pyrolytic carbon coating process. XRD results indicate that the well crystallized composite can be successfully synthesized, and no other impurity phases are detected. SEM and TEM results reveal that the Na2MnPO4F/C samples show intact hollow spherical architecture, and the hollow spherical shells with an average thickness of 150 nm-250 nm are composed of nanosized primary particles. Furthermore, the amorphous carbon layer is uniformly coated on the surface of the hollow sphere, and the nanosized Na2MnPO4F particles are well embedded in the carbon networks. Consequently, the hollow sphere structure Na2MnPO4F/C shows enhanced electrochemical performance. Especially, it is the first time that the obvious potential platforms (∼3.6 V) are observed during the charge and discharge process at room temperature.

  15. A Microfiltration Polymer-Based Hollow-Fiber Cathode as a Promising Advanced Material for Simultaneous Recovery of Energy and Water

    KAUST Repository

    Katuri, Krishna; Bettahalli Narasimha, Murthy Srivatsa; Wang, Xianbin; Matar, Gerald; Chisca, Stefan; Nunes, Suzana Pereira; Saikaly, Pascal

    2016-01-01

    A novel electrocatalytic and microfiltration polymeric hollow fiber is fabricated for simultaneous recovery of energy (H2) and clean fresh water from wastewater, hence addressing two grand challenges facing society in the current century (i.e., providing adequate supplies of clean fresh water and energy as the world's population increases).

  16. A Microfiltration Polymer-Based Hollow-Fiber Cathode as a Promising Advanced Material for Simultaneous Recovery of Energy and Water

    KAUST Repository

    Katuri, Krishna

    2016-09-12

    A novel electrocatalytic and microfiltration polymeric hollow fiber is fabricated for simultaneous recovery of energy (H2) and clean fresh water from wastewater, hence addressing two grand challenges facing society in the current century (i.e., providing adequate supplies of clean fresh water and energy as the world\\'s population increases).

  17. Reservoir Cathode for Electric Space Propulsion, Phase II

    Data.gov (United States)

    National Aeronautics and Space Administration — We propose a hollow reservoir cathode to improve performance in ion and Hall thrusters. We will adapt our existing reservoir cathode technology to this purpose....

  18. Cauliflower-like SnO2 hollow microspheres as anode and carbon fiber as cathode for high performance quantum dot and dye-sensitized solar cells

    Science.gov (United States)

    Ganapathy, Veerappan; Kong, Eui-Hyun; Park, Yoon-Cheol; Jang, Hyun Myung; Rhee, Shi-Woo

    2014-02-01

    Cauliflower-like tin oxide (SnO2) hollow microspheres (HMS) sensitized with multilayer quantum dots (QDs) as photoanode and alternative stable, low-cost counter electrode are employed for the first time in QD-sensitized solar cells (QDSCs). Cauliflower-like SnO2 hollow spheres mainly consist of 50 nm-sized agglomerated nanoparticles; they possess a high internal surface area and light scattering in between the microspheres and shell layers. This makes them promising photoanode material for both QDSCs and dye-sensitized solar cells (DSCs). Successive ionic layer adsorption and reaction (SILAR) method and chemical bath deposition (CBD) are used for QD-sensitizing the SnO2 microspheres. Additionally, carbon-nanofiber (CNF) with a unique structure is used as an alternative counter electrode (CE) and compared with the standard platinum (Pt) CE. Their electrocatalytic properties are measured using electrochemical impedance spectroscopy (EIS), cyclic voltammetry (CV), and Tafel-polarization. Under 1 sun illumination, solar cells made with hollow SnO2 photoanode sandwiched with the stable CNF CE showed a power conversion efficiency of 2.5% in QDSCs and 3.0% for DSCs, which is quite promising with the standard Pt CE (QDSCs: 2.1%, and DSCs: 3.6%).Cauliflower-like tin oxide (SnO2) hollow microspheres (HMS) sensitized with multilayer quantum dots (QDs) as photoanode and alternative stable, low-cost counter electrode are employed for the first time in QD-sensitized solar cells (QDSCs). Cauliflower-like SnO2 hollow spheres mainly consist of 50 nm-sized agglomerated nanoparticles; they possess a high internal surface area and light scattering in between the microspheres and shell layers. This makes them promising photoanode material for both QDSCs and dye-sensitized solar cells (DSCs). Successive ionic layer adsorption and reaction (SILAR) method and chemical bath deposition (CBD) are used for QD-sensitizing the SnO2 microspheres. Additionally, carbon-nanofiber (CNF) with a

  19. Numerical simulation of the insert chemistry of the hollow cathode from the deep space 1 ion engine 30,000 Hrs life test

    OpenAIRE

    Coletti, Michele; Grubisic, Angelo; Gabriel, Stephen

    2007-01-01

    A model for the insert chemistry developed by the authors and based on the knowledge of the BaO – CaO – Al2O3 ternary system the ELT discharge cathode insert from the Deep Space 1 life test has been simulated. The computed data show a good agreement with the experimental one; the agreement increase with the imposition of boundary conditions closer to the experimental evidence. Tungsten deposition effect have been introduced into the model using experimental data and further improving the agre...

  20. Cathode for Electric Space Propulsion Utilizing Iodine as Propellant, Phase I

    Data.gov (United States)

    National Aeronautics and Space Administration — We propose a hollow reservoir cathode suitable for use in ion or Hall thrusters which utilizes iodine as a propellant. Reservoir cathodes have several unique...

  1. Physical Processes in High Current Hollow Cathodes

    Data.gov (United States)

    National Aeronautics and Space Administration — The next generation of space exploration missions, such as the asteroid return mission and the human exploration of Mars, are not feasible with the technology that...

  2. Electron beam generation form a superemissive cathode

    International Nuclear Information System (INIS)

    Hsu, T.-Y.; Liou, R.-L.; Kirkman-Amemiya, G.; Gundersen, M.A.

    1991-01-01

    An experimental study of electron beams produced by a superemissive cathode in the Back-Lighted Thyratron (BLT) and the pseudospark is presented. This work is motivated by experiments demonstrating very high current densities (≥10 kA/cm 2 over an area of 1 cm 2 ) from the pseudospark and BLT cathode. This high-density current is produced by field-enhanced thermionic emission from the ion beam-heated surface of a molybdenum cathode. This work reports the use of this cathode as a beam source, and is to be distinguished from previous work reporting hollow cathode-produced electron beams. An electron beam of more than 260 A Peak current has been produced with 15 kV applied voltage. An efficiency of ∼10% is estimated. These experimental results encourage further investigation of the super-emissive cathode as an intense electron beam source for applications including accelerator technology

  3. Study on the cathode of ion source for neutral beam injector

    International Nuclear Information System (INIS)

    Tanaka, Shigeru

    1983-08-01

    Durability of the cathode is an important problem in developing a high power long pulse ion source for neutral beam injector. The Purpose of this study is to develope a long life cathode and investigate the applicability of it to the source. Directly heated filaments which are commonly used as the cathode of injector source do not live very long in general. In the present work, an indirectly heated hollow cathode made of impregnated porous tungsten tube is proposed as the alternative of the directly heated cathode. At first, we fabricated a small hollow cathode to study the discharge characteristcs in a bell-jar configuration and to apply it to a duoPIGatron hydrogen ion source. The experiment showed that the gas flow rate for sustaining the stable arc discharge in the discharge chamber becomes higher than that when the filament cathode is used. To solve this problem, an experiment for gas reduction was made using a newly fabricated larger hollow cathode and a magnetic multi-pole ion source. The influence of the orifice diameter, the effect of a button and of magnetic field on the gas flow rate were experimentally studied and a method for gas reduction was found. In addition, effect of the magnetic field on the characteristics of the hollow cathode ion source was examined in detail and an optimum field configuration around the cathode was found. Finally, beam extraction from an intensively cooled hollow cathode ion source for up to 10 sec was successfully carried out. (author)

  4. Numerical study on rectangular microhollow cathode discharge

    International Nuclear Information System (INIS)

    He Shoujie; Ouyang Jiting; He Feng; Li Shang

    2011-01-01

    Rectangular microhollow cathode discharge in argon is investigated by using two-dimensional time-dependent self-consistent fluid model. The electric potential, electric field, particle density, and mean electron energy are calculated. The results show that hollow cathode effect can be onset in the present configuration, with strong electric field and high mean electron energy in the cathode fall while high density and quasineutral plasma in the negative glow. The potential well and electric filed reversal are formed in the negative glow region. It is suggested that the presence of large electron diffusion flux necessitates the field reversal and potential well.

  5. Cathode Effects in Cylindrical Hall Thrusters

    Energy Technology Data Exchange (ETDEWEB)

    Granstedt, E.M.; Raitses, Y.; Fisch, N. J.

    2008-09-12

    Stable operation of a cylindrical Hall thruster (CHT) has been achieved using a hot wire cathode, which functions as a controllable electron emission source. It is shown that as the electron emission from the cathode increases with wire heating, the discharge current increases, the plasma plume angle reduces, and the ion energy distribution function shifts toward higher energies. The observed effect of cathode electron emission on thruster parameters extends and clarifies performance improvements previously obtained for the overrun discharge current regime of the same type of thruster, but using a hollow cathode-neutralizer. Once thruster discharge current saturates with wire heating, further filament heating does not affect other discharge parameters. The saturated values of thruster discharge parameters can be further enhanced by optimal placement of the cathode wire with respect to the magnetic field.

  6. Hollow MEMS

    DEFF Research Database (Denmark)

    Larsen, Peter Emil

    Miniaturization of electro mechanical sensor systems to the micro range and beyond has shown impressive sensitivities measuring sample properties like mass, viscosity, acceleration, pressure and force just to name a few applications. In order to enable these kinds of measurements on liquid samples...... a hollow MEMS sensor has been designed, fabricated and tested. Combined density, viscosity, buoyant mass spectrometry and IR absorption spectroscopy are possible on liquid samples and micron sized suspended particles (e.g. single cells). Measurements are based on changes in the resonant behavior...... of these sensors. Optimization of the microfabrication process has led to a process yield of almost 100% .This is achieved despite the fact, that the process still offers a high degree of flexibility. By simple modifications the Sensor shape can be optimized for different size ranges and sensitivities...

  7. Fabrication of polymeric hollow nanospheres, hollow nanocubes and hollow plates

    Science.gov (United States)

    Cheng, Daming; Xia, Haibing; Chan, Hardy Sze On

    2006-03-01

    A facile strategy for fabricating polypyrrole-chitosan (PPy-CS) hollow nanostructures with different shapes (sphere, cube and plate) and a wide range of sizes (from 35 to 600 nm) is described. These hollow structures have been fabricated using silver bromide as a single template material for polymer nucleation and growth. PPy-CS hollow nanostructures are formed by reaction with an etching agent to remove the core. These hollow nanostructures have been extensively characterized using various techniques such as TEM, FT-IR, UV-vis, and XRD.

  8. Analysis of cathode geometry to minimize cathode erosion in direct current microplasma jet

    Energy Technology Data Exchange (ETDEWEB)

    Causa, Federica [Dipartimento di Scienze dell' Ambiente, della Sicurezza, del Territorio, degli Alimenti e della Salute, Universita degli studi di Messina, 98122 Messina (Italy); Ghezzi, Francesco; Caniello, Roberto; Grosso, Giovanni [Istituto di Fisica del Plasma, Consiglio Nazionale delle Ricerche, EURATOM-ENEA-CNR Association, Via R. Cozzi 53, 20125 Milano (Italy); Dellasega, David [Istituto di Fisica del Plasma, Consiglio Nazionale delle Ricerche, EURATOM-ENEA-CNR Association, Via R. Cozzi 53, 20125 Milano (Italy); Dipartimento di Energia, Politecnico di Milano, Via Ponzio 34/3, 20133 Milano (Italy)

    2012-12-15

    Microplasma jets are now widely used for deposition, etching, and materials processing. The present study focuses on the investigation of the influence of cathode geometry on deposition quality, for microplasma jet deposition systems in low vacuum. The interest here is understanding the influence of hydrogen on sputtering and/or evaporation of the electrodes. Samples obtained with two cathode geometries with tapered and rectangular cross-sections have been investigated experimentally by scanning electron microscopy and energy dispersion X-ray spectroscopy. Samples obtained with a tapered-geometry cathode present heavy contamination, demonstrating cathode erosion, while samples obtained with a rectangular-cross-section cathode are free from contamination. These experimental characteristics were explained by modelling results showing a larger radial component of the electric field at the cathode inner wall of the tapered cathode. As a result, ion acceleration is larger, explaining the observed cathode erosion in this case. Results from the present investigation also show that the ratio of radial to axial field components is larger for the rectangular geometry case, thus, qualitatively explaining the presence of micro-hollow cathode discharge over a wide range of currents observed in this case. In the light of the above findings, the rectangular cathode geometry is considered to be more effective to achieve cleaner deposition.

  9. Cathode follower RF system with frequency modulation

    International Nuclear Information System (INIS)

    Irie, Y.; Yano, Y.; Kaneko, N.; Kobayashi, Y.

    1994-01-01

    A model RF system with a cathode follower was tested under frequency modulation in the 1-3.5 MHz range. The repetition rate was 40 Hz. The oscillation was stable, and the output impedance was measured to be around 20 ohm. (author)

  10. Integrated Energetic Ion Mitigation for High Power Plasma Cathodes, Phase I

    Data.gov (United States)

    National Aeronautics and Space Administration — The innovation proposed is a hollow cathode that integrates mitigation methods to suppress wear to the keeper. Recent advances in the magnetic topology in Hall...

  11. Advanced Cathodes for Next Generation Electric Propulsion Technology

    Science.gov (United States)

    2008-03-01

    learning opportunity- of which it did. Finally, Dr. Glen Perram of the physics department at AFIT was so gracious to let us borrow his Langmuir Probe in...Applications Like Hall thrusters, ion thrusters also employ hollow cathodes.15,18,19,20,21 Harold Kaufman at NASA Glen Research Center (GRC... brittle nature, a problem common to CeB6 and LaB6. As a result, easier to machine polycrystalline inserts for LaB6 have been used for hollow cathodes in

  12. Long-life cathode for the Berkeley-type ion source

    International Nuclear Information System (INIS)

    Fink, J.H.; Biagi, L.A.

    1977-01-01

    Preliminary experiments indicate that a hollow cathode, made from impregnated tungsten emitters, can be adapted for the Lawrence Berkeley Laboratory (LBL)/Lawrence Livermore Laboratory (LLL) ion source. Such cathodes could be the basis of a long life, continuously operated positive-ion source

  13. Design and experiment of high-current low-pressure plasma-cathode e-gun

    International Nuclear Information System (INIS)

    Xie Wenkai; Li Xiaoyun; Wang Bin; Meng Lin; Yan Yang; Gao Xinyan

    2006-01-01

    The preliminary design of a new high-power low pressure plasma-cathode e-gun is presented. Based on the hollow cathode effect and low-pressure glow discharge empirical formulas, the hollow cathode, the accelerating gap, and the working gas pressure region are given. The general experimental device of the low-pressure plasma cathode electron-gun generating high current density e-beam source is shown. Experiments has been done in continuous filled-in gases and gases-puff condition, and the discharging current of 150-200 A, the width of 60 μs and the collector current of 30-80 A, the width of 60 μs are obtained. The results show that the new plasma cathode e-gun can take the place of material cathode e-gun, especially in plasma filled microwave tubes. (authors)

  14. Development of plasma cathode electron guns

    Science.gov (United States)

    Oks, Efim M.; Schanin, Peter M.

    1999-05-01

    The status of experimental research and ongoing development of plasma cathode electron guns in recent years is reviewed, including some novel upgrades and applications to various technological fields. The attractiveness of this kind of e-gun is due to its capability of creating high current, broad or focused beams, both in pulsed and steady-state modes of operation. An important characteristic of the plasma cathode electron gun is the absence of a thermionic cathode, a feature which leads to long lifetime and reliable operation even in the presence of aggressive background gas media and at fore-vacuum gas pressure ranges such as achieved by mechanical pumps. Depending on the required beam parameters, different kinds of plasma discharge systems can be used in plasma cathode electron guns, such as vacuum arcs, constricted gaseous arcs, hollow cathode glows, and two kinds of discharges in crossed E×B fields: Penning and magnetron. At the present time, plasma cathode electron guns provide beams with transverse dimension from fractional millimeter up to about one meter, beam current from microamperes to kiloamperes, beam current density up to about 100 A/cm2, pulse duration from nanoseconds to dc, and electron energy from several keV to hundreds of keV. Applications include electron beam melting and welding, surface treatment, plasma chemistry, radiation technologies, laser pumping, microwave generation, and more.

  15. 3D hollow sphere Co3O4/MnO2-CNTs: Its high-performance bi-functional cathode catalysis and application in rechargeable zinc-air battery

    Directory of Open Access Journals (Sweden)

    Xuemei Li

    2017-07-01

    Full Text Available There has been a continuous need for high active, excellently durable and low-cost electrocatalysts for rechargeable zinc-air batteries. Among many low-cost metal based candidates, transition metal oxides with the CNTs composite have gained increasing attention. In this paper, the 3-D hollow sphere MnO2 nanotube-supported Co3O4 nanoparticles and its carbon nanotubes hybrid material (Co3O4/MnO2-CNTs have been synthesized via a simple co-precipitation method combined with post-heat treatment. The morphology and composition of the catalysts are thoroughly analyzed through SEM, TEM, TEM-mapping, XRD, EDX and XPS. In comparison with the commercial 20% Pt/C, Co3O4/MnO2, bare MnO2 nanotubes and CNTs, the hybrid Co3O4/MnO2-CNTs-350 exhibits perfect bi-functional catalytic activity toward oxygen reduction reaction and oxygen evolution reaction under alkaline condition (0.1 M KOH. Therefore, high cell performances are achieved which result in an appropriate open circuit voltage (∼1.47 V, a high discharge peak power density (340 mW cm−2 and a large specific capacity (775 mAh g−1 at 10 mA cm−2 for the primary Zn-air battery, a small charge–discharge voltage gap and a high cycle-life (504 cycles at 10 mA cm−2 with 10 min per cycle for the rechargeable Zn-air battery. In particular, the simple synthesis method is suitable for a large-scale production of this bifunctional material due to a green, cost effective and readily available process. Keywords: Bi-functional catalyst, Oxygen reduction reaction, Oxygen evolution reaction, Activity and stability, Rechargeable zinc-air battery

  16. Nanotube cathodes.

    Energy Technology Data Exchange (ETDEWEB)

    Overmyer, Donald L.; Lockner, Thomas Ramsbeck; Siegal, Michael P.; Miller, Paul Albert

    2006-11-01

    Carbon nanotubes have shown promise for applications in many diverse areas of technology. In this report we describe our efforts to develop high-current cathodes from a variety of nanotubes deposited under a variety of conditions. Our goal was to develop a one-inch-diameter cathode capable of emitting 10 amperes of electron current for one second with an applied potential of 50 kV. This combination of current and pulse duration significantly exceeds previously reported nanotube-cathode performance. This project was planned for two years duration. In the first year, we tested the electron-emission characteristics of nanotube arrays fabricated under a variety of conditions. In the second year, we planned to select the best processing conditions, to fabricate larger cathode samples, and to test them on a high-power relativistic electron beam generator. In the first year, much effort was made to control nanotube arrays in terms of nanotube diameter and average spacing apart. When the project began, we believed that nanotubes approximately 10 nm in diameter would yield sufficient electron emission properties, based on the work of others in the field. Therefore, much of our focus was placed on measured field emission from such nanotubes grown on a variety of metallized surfaces and with varying average spacing between individual nanotubes. We easily reproduced the field emission properties typically measured by others from multi-wall carbon nanotube arrays. Interestingly, we did this without having the helpful vertical alignment to enhance emission; our nanotubes were randomly oriented. The good emission was most likely possible due to the improved crystallinity, and therefore, electrical conductivity, of our nanotubes compared to those in the literature. However, toward the end of the project, we learned that while these 10-nm-diameter CNTs had superior crystalline structure to the work of others studying field emission from multi-wall CNT arrays, these nanotubes still

  17. Nanotube cathodes

    International Nuclear Information System (INIS)

    Overmyer, Donald L.; Lockner, Thomas Ramsbeck; Siegal, Michael P.; Miller, Paul Albert

    2006-01-01

    Carbon nanotubes have shown promise for applications in many diverse areas of technology. In this report we describe our efforts to develop high-current cathodes from a variety of nanotubes deposited under a variety of conditions. Our goal was to develop a one-inch-diameter cathode capable of emitting 10 amperes of electron current for one second with an applied potential of 50 kV. This combination of current and pulse duration significantly exceeds previously reported nanotube-cathode performance. This project was planned for two years duration. In the first year, we tested the electron-emission characteristics of nanotube arrays fabricated under a variety of conditions. In the second year, we planned to select the best processing conditions, to fabricate larger cathode samples, and to test them on a high-power relativistic electron beam generator. In the first year, much effort was made to control nanotube arrays in terms of nanotube diameter and average spacing apart. When the project began, we believed that nanotubes approximately 10 nm in diameter would yield sufficient electron emission properties, based on the work of others in the field. Therefore, much of our focus was placed on measured field emission from such nanotubes grown on a variety of metallized surfaces and with varying average spacing between individual nanotubes. We easily reproduced the field emission properties typically measured by others from multi-wall carbon nanotube arrays. Interestingly, we did this without having the helpful vertical alignment to enhance emission; our nanotubes were randomly oriented. The good emission was most likely possible due to the improved crystallinity, and therefore, electrical conductivity, of our nanotubes compared to those in the literature. However, toward the end of the project, we learned that while these 10-nm-diameter CNTs had superior crystalline structure to the work of others studying field emission from multi-wall CNT arrays, these nanotubes still

  18. Influence of thin porous Al2O3 layer on aluminum cathode to the Hα line shape in glow discharge

    International Nuclear Information System (INIS)

    Steflekova, V.; Sisovic, N. M.; Konjevic, N.

    2009-01-01

    The results of the Balmer alfa line shape study in a plane cathode-hollow anode Grimm discharge with aluminum (Al) cathode covered with thin layer of porous Al 2 O 3 are presented. The comparison with same line profile recorded with pure Al cathode shows lack of excessive Doppler broadened line wings, which are always detected in glow discharge with metal cathode. The effect is explained by the lack of strong electric field in the cathode sheath region, which is missing in the presence of thin oxide layer in, so called, spray discharge.

  19. Nanosized aluminum nitride hollow spheres formed through a self-templating solid-gas interface reaction

    International Nuclear Information System (INIS)

    Zheng Jie; Song Xubo; Zhang Yaohua; Li Yan; Li Xingguo; Pu Yikang

    2007-01-01

    Nanosized aluminum nitride hollow spheres were synthesized by simply heating aluminum nanoparticles in ammonia at 1000 deg. C. The as-synthesized sphere shells are polycrystalline with cavity diameters ranging from 15 to 100 nm and shell thickness from 5 to 15 nm. The formation mechanism can be explained by the nanoscale Kirkendall effect, which results from the difference in diffusion rates between aluminum and nitrogen. The Al nanoparticles served as both reactant and templates for the hollow sphere formation. The effects of precursor particle size and temperature were also investigated in terms of product morphology. Room temperature cathode luminescence spectrum of the nanosized hollow spheres showed a broad emission band centered at 415 nm, which is originated from oxygen related luminescence centers. The hollow structure survived a 4-h heat treatment at 1200 deg. C, exhibiting excellent thermal stability. - Graphical abstract: Nanosized aluminum nitride hollow spheres were synthesized by nitridation of aluminum nanoparticles at 1000 deg. C using ammonia

  20. Verification of high efficient broad beam cold cathode ion source

    Energy Technology Data Exchange (ETDEWEB)

    Abdel Reheem, A. M., E-mail: amreheem2009@yahoo.com [Accelerators and Ion Sources Department, Nuclear Research Center, Atomic Energy Authority, P.N.13759, Cairo (Egypt); Radiation Physics Department, National Center for Radiation Research and Technology (NCRRT), Atomic Energy Authority (AEA), Cairo (Egypt); Ahmed, M. M. [Physics Department, Faculty of Science, Helwan University, Cairo (Egypt); Abdelhamid, M. M.; Ashour, A. H. [Radiation Physics Department, National Center for Radiation Research and Technology (NCRRT), Atomic Energy Authority (AEA), Cairo (Egypt)

    2016-08-15

    An improved form of cold cathode ion source has been designed and constructed. It consists of stainless steel hollow cylinder anode and stainless steel cathode disc, which are separated by a Teflon flange. The electrical discharge and output characteristics have been measured at different pressures using argon, nitrogen, and oxygen gases. The ion exit aperture shape and optimum distance between ion collector plate and cathode disc are studied. The stable discharge current and maximum output ion beam current have been obtained using grid exit aperture. It was found that the optimum distance between ion collector plate and ion exit aperture is equal to 6.25 cm. The cold cathode ion source is used to deposit aluminum coating layer on AZ31 magnesium alloy using argon ion beam current which equals 600 μA. Scanning electron microscope and X-ray diffraction techniques used for characterizing samples before and after aluminum deposition.

  1. Cathodic protection -- Rectifier 46

    International Nuclear Information System (INIS)

    Lane, W.M.

    1995-01-01

    This Acceptance Test Procedure (ATP) has been prepared to demonstrate that the cathodic protection system functions as required by project criteria. The cathodic protection system is for the tank farms on the Hanford Reservation. The tank farms store radioactive waste

  2. Cathodic protection -- Rectifier 47

    International Nuclear Information System (INIS)

    Lane, W.M.

    1995-01-01

    This Acceptance Test Procedure (ATP) has been prepared to demonstrate that the cathodic protection system functions as required by project criteria. The cathodic protection system is for the tank farms at the Hanford Reservation. The tank farms store radioactive waste

  3. Long pulse, plasma cathode E-gun

    International Nuclear Information System (INIS)

    Goebel, D.M.; Schumacher, R.W.; Watkins, R.M.

    1993-01-01

    A unique, long-pulse E-gun has been developed for high-power tube applications. The Hollow-Cathode-Plasma (HCP) E-gun overcomes the limitations of conventional thermionic-cathode guns that have limited current density (typically ≤ 10 A/cm 2 ) or field-emission guns that offer high current density but suffer from short pulsewidth capability (typically 50 A/cm 2 ), long-pulse operation without gap closure, and also requires no cathode-heater power. The gun employs a low-pressure glow discharge inside a hollow cathode (HC) structure to provide a stable, uniform plasma surface from which a high current-density electron beam can be extracted. The plasma density is controlled by a low-voltage HC discharge pulser to produce the desired electron current density at the first grid of a multi-grid accelerator system. A dc high-voltage electron-beam supply accelerates the electrons across the gap, while the HC pulser modulates the beam current to generate arbitrary pulse waveforms. The electron accelerator utilizes a multi-aperture array that produces a large area, high perveance (>35 μpervs) beam consisting initially of many individual beamlets. The E-beam is normally operated without an applied magnetic field in the ion-focused regime, where the plasma produced by beam ionization of a background gas space-charge neutralizes the beam, and the Bennett self-pinch compresses the beamlets and increases the current density. The self-pinched beam has been observed to propagate over a meter without beam breakup or instabilities. The HCP E-gun has been operated at voltages up to 150 kV, currents up to 750 A, and pulse lengths of up to 120 μsec

  4. Hollow-Core Fiber Lamp

    Science.gov (United States)

    Yi, Lin (Inventor); Tjoelker, Robert L. (Inventor); Burt, Eric A. (Inventor); Huang, Shouhua (Inventor)

    2016-01-01

    Hollow-core capillary discharge lamps on the millimeter or sub-millimeter scale are provided. The hollow-core capillary discharge lamps achieve an increased light intensity ratio between 194 millimeters (useful) and 254 millimeters (useless) light than conventional lamps. The capillary discharge lamps may include a cone to increase light output. Hollow-core photonic crystal fiber (HCPCF) may also be used.

  5. HOLLOW FIBRE MEMBRANE

    NARCIS (Netherlands)

    Wessling, Matthias; Stamatialis, Dimitrios; Kopec, K.K.; Dutczak, S.M.

    2011-01-01

    The present invention relates to a process for manufacturing a hollow fibre membrane having a supporting layer and a separating layer, said process comprising: (a)extruding a spinning composition comprising a first polymer and a solvent for the first polymer through an inner annular orifice of a

  6. HOLLOW FIBRE MEMBRANE

    NARCIS (Netherlands)

    Wessling, Matthias; Stamatialis, Dimitrios; Kopec, K.K.; Dutczak, S.M.

    2013-01-01

    The present invention relates to a process for manufacturing a hollow fibre membrane having a supporting layer and a separating layer, said process comprising: (a) extruding a spinning composition comprising a first polymer and a solvent for the first polymer through an inner annular orifice of a

  7. Development of hollow anode penning ion source for laboratory application

    Energy Technology Data Exchange (ETDEWEB)

    Das, B.K., E-mail: dasbabu31@gmail.com [Energetics and Electromagnetics Division, Bhabha Atomic Research Centre, Autonagar, Visakhapatnam (India); Shyam, A.; Das, R. [Energetics and Electromagnetics Division, Bhabha Atomic Research Centre, Autonagar, Visakhapatnam (India); Rao, A.D.P. [Department of Nuclear Physics, Andhra University, Visakhapatnam (India)

    2012-03-21

    The research work presented here focuses for the development of miniature penning type ion source. One hollow anode penning type ion source was developed in our laboratory. The size of the ion source is 38 mm diameter and 55 mm length. The ion source consists of two cathodes, a hollow anode and one piece of rare earth permanent magnet. The plasma was created in the plasma region between cathodes and the hollow anode. The J Multiplication-Sign B force in the region helps for efficient ionization of the gas even in the high vacuum region{approx}1 Multiplication-Sign 10{sup -5} Torr. The ions were extracted in the axial direction with help of the potential difference between the electrodes and the geometry of the extraction angle. The effect of the extraction electrode geometry for efficient extraction of the ions from the plasma region was examined. This ion source is a self extracted ion source. The self extracted phenomena reduce the cost and the size of the ion source. The extracted ion current was measured by a graphite probe. An ion current of more than 200 {mu}A was observed at the probe placed 70 mm apart from the extraction electrode. In this paper, the structure of the ion source, effect of operating pressure, potential difference and the magnetic field on the extracted ion current is reported.

  8. Inversion of the OH 1720-MHz line

    International Nuclear Information System (INIS)

    Elitzur, M.

    1975-01-01

    It is shown that the OH 1720-MHz line can be strongly inverted by collisions which excite the rotation states. It is also argued that radiative pumps (of any wave length) can invert strongly only the 1612-MHz line. (author)

  9. Study of electron current extraction from a radio frequency plasma cathode designed as a neutralizer for ion source applications

    Energy Technology Data Exchange (ETDEWEB)

    Jahanbakhsh, Sina, E-mail: sinajahanbakhsh@gmail.com; Satir, Mert; Celik, Murat [Department of Mechanical Engineering, Bogazici University, Istanbul 34342 (Turkey)

    2016-02-15

    Plasma cathodes are insert free devices that are developed to be employed as electron sources in electric propulsion and ion source applications as practical alternatives to more commonly used hollow cathodes. Inductively coupled plasma cathodes, or Radio Frequency (RF) plasma cathodes, are introduced in recent years. Because of its compact geometry, and simple and efficient plasma generation, RF plasma source is considered to be suitable for plasma cathode applications. In this study, numerous RF plasma cathodes have been designed and manufactured. Experimental measurements have been conducted to study the effects of geometric and operational parameters. Experimental results of this study show that the plasma generation and electron extraction characteristics of the RF plasma cathode device strongly depend on the geometric parameters such as chamber diameter, chamber length, orifice diameter, orifice length, as well as the operational parameters such as RF power and gas mass flow rate.

  10. Cathodic Protection Model Facility

    Data.gov (United States)

    Federal Laboratory Consortium — FUNCTION: Performs Navy design and engineering of ship and submarine impressed current cathodic protection (ICCP) systems for underwater hull corrosion control and...

  11. Hollow bunches production

    CERN Document Server

    Hancock, S

    2017-01-01

    Hollow bunches address the issue of high-brightnessbeams suffering from transverse emittance growth in a strongspace charge regime. During the Proton Synchrotron (PS)injection plateau, the negative space charge tune shift canpush the beam onto theQy=6integer resonance. Modify-ing the longitudinal bunch profile in order to reduce the peakline charge density alleviates the detrimental impact of spacecharge. To this end we first produce longitudinally hollowphase space distributions in the PS Booster by exciting aparametric resonance with the phase loop feedback system.These inherently flat bunches are then transferred to the PS,where the beam becomes less prone to the emittance growthcaused by the integer resonance.During the late 2016 machine development sessions inthe PS Booster we profited from solved issues from 2015and managed to reliably extract hollow bunches of1.3eVsmatched longitudinal area. Furthermore, first results to cre-ate hollow bunches with larger longitudinal emittances to-wards the LHC Inject...

  12. Electrodepositing of Au on hollow PS micro-spheres

    International Nuclear Information System (INIS)

    Sun Jingyuan; Zhang Yunwang; Du Kai; Wan Xiaobo; Xiao Jiang; Zhang Wei; Zhang Lin; Chen Jing

    2010-01-01

    Using the self-regulating new micro-sphere electrodepositing device, the techniques of electrodepositing gold on hollow PS micro-spheres were established. The experiment was carried out under the following conditions: voltage was about 0.7 ∼ 0.8 V, current density was 2.0 mA · cm -2 , the temperature was 45 degree C, cathode rotating rate was 250 r · min -1 , flow rate of the solution was 7 mL · min -1 · cm -2 . Hollow gold-plated micro-spheres were prepared with well spherical symmetry, uniform thickness and surface smoothness under 500 nm. The speed of the gold depositing was 6 μm · h -1 . (authors)

  13. Mercury - the hollow planet

    Science.gov (United States)

    Rothery, D. A.

    2012-04-01

    Mercury is turning out to be a planet characterized by various kinds of endogenous hole (discounting impact craters), which are compared here. These include volcanic vents and collapse features on horizontal scales of tens of km, and smaller scale depressions ('hollows') associated with bright crater-floor deposits (BCFD). The BCFD hollows are tens of metres deep and kilometres or less across and are characteristically flat-floored, with steep, scalloped walls. Their form suggests that they most likely result from removal of surface material by some kind of mass-wasting process, probably associated with volume-loss caused by removal (via sublimation?) of a volatile component. These do not appear to be primarily a result of undermining. Determining the composition of the high-albedo bluish surface coating in BCFDs will be a key goal for BepiColombo instruments such as MIXS (Mercury Imaging Xray Spectrometer). In contrast, collapse features are non-circular rimless pits, typically on crater floors (pit-floor craters), whose morphology suggests collapse into void spaces left by magma withdrawal. This could be by drainage of either erupted lava (or impact melt) or of shallowly-intruded magma. Unlike the much smaller-scale BCFD hollows, these 'collapse pit' features tend to lack extensive flat floors and instead tend to be close to triangular in cross-section with inward slopes near to the critical angle of repose. The different scale and morphology of BCFD hollows and collapse pits argues for quite different modes of origin. However, BCFD hollows adjacent to and within the collapse pit inside Scarlatti crater suggest that the volatile material whose loss was responsible for the growth of the hollows may have been emplaced in association with the magma whose drainage caused the main collapse. Another kind of volcanic collapse can be seen within a 25 km-wide volcanic vent outside the southern rim of the Caloris basin (22.5° N, 146.1° E), on a 28 m/pixel MDIS NAC image

  14. Waveform digitizing at 500 MHz

    International Nuclear Information System (INIS)

    Atiya, M.; Ito, M.; Haggerty, J.; Ng, C.; Sippach, F.W.

    1988-01-01

    Experiment E787 at Brookhaven National Laboratory is designed to study the decay K + → π + ν/bar /nu// to a sensitivity of 2 /times/ 10 -10 . To achieve acceptable muon rejection it is necessary to couple traditional methods (range/energy/momentum correlation) with observation of the (π + → μ + ν, μ + → e + ν/bar /nu//) decay sequence in scintillator. We report on the design and construction of 200 channels of relatively low cost solid state waveform digitizers. The distinguishing features are: 8 bits dynamic range, 500 MHz sampling, zero suppression on the fly, deep memory (up to .5 msec), and fast readout time (100 μsec for the entire system). We report on data obtained during the February-May 1988 run showing performance of the system for the observation of the above decay. 8 figs

  15. Waveform digitizing at 500 MHz

    International Nuclear Information System (INIS)

    Atiya, M.; Ito, M.; Haggerty, J.; Ng, C.; Sippach, F.W.

    1988-01-01

    Experiment E787 at Brookhaven National Laboratory is designed to study the decay K + → π + ν/bar /nu// to a sensitivity of 2 /times/ 10/sup /minus/10/. To achieve acceptable muon rejection it is necessary to couple traditional methods (range/energy/momentum correlation) with observation of the π + → μ + → e + ν/bar /nu// decay sequence in scintillator. We report on the design and construction of over 200 channels of relatively low cost solid state waveform digitizers. The distinguishing features are: 8 bits dynamic range, 500 MHz sampling, zero suppression on the fly, deep memory (up to .5 msec), and fast readout time (100 μsec for the entire system). We report on data obtained during the February--May 1988 run showing performance of the system for the observation of the above decay. 9 figs

  16. A multiple gap plasma cathode electron gun and its electron beam analysis in self and trigger breakdown modes.

    Science.gov (United States)

    Kumar, Niraj; Pal, Dharmendra Kumar; Jadon, Arvind Singh; Pal, Udit Narayan; Rahaman, Hasibur; Prakash, Ram

    2016-03-01

    In the present paper, a pseudospark discharge based multiple gap plasma cathode electron gun is reported which has been operated separately in self and trigger breakdown modes using two different gases, namely, argon and hydrogen. The beam current and beam energy have been analyzed using a concentric ring diagnostic arrangement. Two distinct electron beams are clearly seen with hollow cathode and conductive phases. The hollow cathode phase has been observed for ∼50 ns where the obtained electron beam is having low beam current density and high energy. While in conductive phase it is high current density and low energy electron beam. It is inferred that in the hollow cathode phase the beam energy is more for the self breakdown case whereas the current density is more for the trigger breakdown case. The tailor made operation of the hollow cathode phase electron beam can play an important role in microwave generation. Up to 30% variation in the electron beam energy has been achieved keeping the same gas and by varying the breakdown mode operations. Also, up to 32% variation in the beam current density has been achieved for the trigger breakdown mode at optimized trigger position by varying the gas type.

  17. A multiple gap plasma cathode electron gun and its electron beam analysis in self and trigger breakdown modes

    Energy Technology Data Exchange (ETDEWEB)

    Kumar, Niraj; Pal, Udit Narayan; Prakash, Ram [CSIR-Central Electronics Engineering Research Institute (CSIR-CEERI), Pilani, Rajasthan 333031 (India); Academy of Scientific and Innovative Research (AcSIR), CSIR-CEERI Campus, Pilani (India); Pal, Dharmendra Kumar; Jadon, Arvind Singh; Rahaman, Hasibur [CSIR-Central Electronics Engineering Research Institute (CSIR-CEERI), Pilani, Rajasthan 333031 (India)

    2016-03-15

    In the present paper, a pseudospark discharge based multiple gap plasma cathode electron gun is reported which has been operated separately in self and trigger breakdown modes using two different gases, namely, argon and hydrogen. The beam current and beam energy have been analyzed using a concentric ring diagnostic arrangement. Two distinct electron beams are clearly seen with hollow cathode and conductive phases. The hollow cathode phase has been observed for ∼50 ns where the obtained electron beam is having low beam current density and high energy. While in conductive phase it is high current density and low energy electron beam. It is inferred that in the hollow cathode phase the beam energy is more for the self breakdown case whereas the current density is more for the trigger breakdown case. The tailor made operation of the hollow cathode phase electron beam can play an important role in microwave generation. Up to 30% variation in the electron beam energy has been achieved keeping the same gas and by varying the breakdown mode operations. Also, up to 32% variation in the beam current density has been achieved for the trigger breakdown mode at optimized trigger position by varying the gas type.

  18. A multiple gap plasma cathode electron gun and its electron beam analysis in self and trigger breakdown modes

    International Nuclear Information System (INIS)

    Kumar, Niraj; Pal, Udit Narayan; Prakash, Ram; Pal, Dharmendra Kumar; Jadon, Arvind Singh; Rahaman, Hasibur

    2016-01-01

    In the present paper, a pseudospark discharge based multiple gap plasma cathode electron gun is reported which has been operated separately in self and trigger breakdown modes using two different gases, namely, argon and hydrogen. The beam current and beam energy have been analyzed using a concentric ring diagnostic arrangement. Two distinct electron beams are clearly seen with hollow cathode and conductive phases. The hollow cathode phase has been observed for ∼50 ns where the obtained electron beam is having low beam current density and high energy. While in conductive phase it is high current density and low energy electron beam. It is inferred that in the hollow cathode phase the beam energy is more for the self breakdown case whereas the current density is more for the trigger breakdown case. The tailor made operation of the hollow cathode phase electron beam can play an important role in microwave generation. Up to 30% variation in the electron beam energy has been achieved keeping the same gas and by varying the breakdown mode operations. Also, up to 32% variation in the beam current density has been achieved for the trigger breakdown mode at optimized trigger position by varying the gas type.

  19. 47 CFR 101.77 - Public safety licensees in the 1850-1990 MHz, 2110-2150 MHz, and 2160-2200 MHz bands.

    Science.gov (United States)

    2010-10-01

    ..., 2110-2150 MHz, and 2160-2200 MHz bands. 101.77 Section 101.77 Telecommunication FEDERAL COMMUNICATIONS...-1990 MHz, 2110-2150 MHz, and 2160-2200 MHz bands. (a) In order for public safety licensees to qualify... a Police licensee, a Fire Licensee, or an Emergency Medical Licensee as defined in § 90.7 of this...

  20. Nanostructured sulfur cathodes

    KAUST Repository

    Yang, Yuan

    2013-01-01

    Rechargeable Li/S batteries have attracted significant attention lately due to their high specific energy and low cost. They are promising candidates for applications, including portable electronics, electric vehicles and grid-level energy storage. However, poor cycle life and low power capability are major technical obstacles. Various nanostructured sulfur cathodes have been developed to address these issues, as they provide greater resistance to pulverization, faster reaction kinetics and better trapping of soluble polysulfides. In this review, recent developments on nanostructured sulfur cathodes and mechanisms behind their operation are presented and discussed. Moreover, progress on novel characterization of sulfur cathodes is also summarized, as it has deepened the understanding of sulfur cathodes and will guide further rational design of sulfur electrodes. © 2013 The Royal Society of Chemistry.

  1. Arcjet cathode phenomena

    Science.gov (United States)

    Curran, Francis M.; Haag, Thomas W.; Raquet, John F.

    1989-01-01

    Cathode tips made from a number of different materials were tested in a modular arcjet thruster in order to examine cathode phenomena. Periodic disassembly and examination, along with the data collected during testing, indicated that all of the tungsten-based materials behaved similarly despite the fact that in one of these samples the percentage of thorium oxide was doubled and another was 25 percent rhenium. The mass loss rate from a 2 percent thoriated rhenium cathode was found to be an order of magnitude greater than that observed using 2 percent thoriated tungsten. Detailed analysis of one of these cathode tips showed that the molten crater contained pure tungsten to a depth of about 150 microns. Problems with thermal stress cracking were encountered in the testing of a hafnium carbide tip. Post test analysis showed that the active area of the tip had chemically reacted with the propellant. A 100 hour continuous test was run at about 1 kW. Post test analysis revealed no dendrite formation, such as observed in a 30 kW arcjet lifetest, near the cathode crater. The cathodes from both this test and a previously run 1000 hour cycled test displayed nearly identical arc craters. Data and calculations indicate that the mass losses observed in testing can be explained by evaporation.

  2. Birefringent hollow core fibers

    DEFF Research Database (Denmark)

    Roberts, John

    2007-01-01

    Hollow core photonic crystal fiber (HC-PCF), fabricated according to a nominally non-birefringent design, shows a degree of un-controlled birefringence or polarization mode dispersion far in excess of conventional non polarization maintaining fibers. This can degrade the output pulse in many...... applications, and places emphasis on the development of polarization maintaining (PM) HC-PCF. The polarization cross-coupling characteristics of PM HC-PCF are very different from those of conventional PM fibers. The former fibers have the advantage of suffering far less from stress-field fluctuations...... and an increased overlap between the polarization modes at the glass interfaces. The interplay between these effects leads to a wavelength for optimum polarization maintenance, lambda(PM), which is detuned from the wavelength of highest birefringence. By a suitable fiber design involving antiresonance of the core...

  3. Photoacoustic imaging of hidden dental caries by using a bundle of hollow optical fibers

    Science.gov (United States)

    Koyama, Takuya; Kakino, Satoko; Matsuura, Yuji

    2018-02-01

    Photoacoustic imaging system using a bundle of hollow-optical fibers to detect hidden dental caries is proposed. Firstly, we fabricated a hidden caries model with a brown pigment simulating a common color of caries lesion. It was found that high frequency ultrasonic waves are generated from hidden carious part when radiating Nd:YAG laser light with a 532 nm wavelength to occlusal surface of model tooth. We calculated by Fourier transform and found that the waveform from the carious part provides frequency components of approximately from 0.5 to 1.2 MHz. Then a photoacoustic imaging system using a bundle of hollow optical fiber was fabricated for clinical applications. From intensity map of frequency components in 0.5-1.2 MHz, photoacoustic images of hidden caries in the simulated samples were successfully obtained.

  4. Cathode materials review

    Energy Technology Data Exchange (ETDEWEB)

    Daniel, Claus, E-mail: danielc@ornl.gov; Mohanty, Debasish, E-mail: danielc@ornl.gov; Li, Jianlin, E-mail: danielc@ornl.gov; Wood, David L., E-mail: danielc@ornl.gov [Oak Ridge National Laboratory, 1 Bethel Valley Road, MS6472 Oak Ridge, TN 37831-6472 (United States)

    2014-06-16

    The electrochemical potential of cathode materials defines the positive side of the terminal voltage of a battery. Traditionally, cathode materials are the energy-limiting or voltage-limiting electrode. One of the first electrochemical batteries, the voltaic pile invented by Alessandro Volta in 1800 (Phil. Trans. Roy. Soc. 90, 403-431) had a copper-zinc galvanic element with a terminal voltage of 0.76 V. Since then, the research community has increased capacity and voltage for primary (nonrechargeable) batteries and round-trip efficiency for secondary (rechargeable) batteries. Successful secondary batteries have been the lead-acid with a lead oxide cathode and a terminal voltage of 2.1 V and later the NiCd with a nickel(III) oxide-hydroxide cathode and a 1.2 V terminal voltage. The relatively low voltage of those aqueous systems and the low round-trip efficiency due to activation energies in the conversion reactions limited their use. In 1976, Wittingham (J. Electrochem. Soc., 123, 315) and Besenhard (J. Power Sources 1(3), 267) finally enabled highly reversible redox reactions by intercalation of lithium ions instead of by chemical conversion. In 1980, Goodenough and Mizushima (Mater. Res. Bull. 15, 783-789) demonstrated a high-energy and high-power LiCoO{sub 2} cathode, allowing for an increase of terminal voltage far beyond 3 V. Over the past four decades, the international research community has further developed cathode materials of many varieties. Current state-of-the-art cathodes demonstrate voltages beyond any known electrolyte stability window, bringing electrolyte research once again to the forefront of battery research.

  5. Cathode materials review

    International Nuclear Information System (INIS)

    Daniel, Claus; Mohanty, Debasish; Li, Jianlin; Wood, David L.

    2014-01-01

    The electrochemical potential of cathode materials defines the positive side of the terminal voltage of a battery. Traditionally, cathode materials are the energy-limiting or voltage-limiting electrode. One of the first electrochemical batteries, the voltaic pile invented by Alessandro Volta in 1800 (Phil. Trans. Roy. Soc. 90, 403-431) had a copper-zinc galvanic element with a terminal voltage of 0.76 V. Since then, the research community has increased capacity and voltage for primary (nonrechargeable) batteries and round-trip efficiency for secondary (rechargeable) batteries. Successful secondary batteries have been the lead-acid with a lead oxide cathode and a terminal voltage of 2.1 V and later the NiCd with a nickel(III) oxide-hydroxide cathode and a 1.2 V terminal voltage. The relatively low voltage of those aqueous systems and the low round-trip efficiency due to activation energies in the conversion reactions limited their use. In 1976, Wittingham (J. Electrochem. Soc., 123, 315) and Besenhard (J. Power Sources 1(3), 267) finally enabled highly reversible redox reactions by intercalation of lithium ions instead of by chemical conversion. In 1980, Goodenough and Mizushima (Mater. Res. Bull. 15, 783-789) demonstrated a high-energy and high-power LiCoO 2 cathode, allowing for an increase of terminal voltage far beyond 3 V. Over the past four decades, the international research community has further developed cathode materials of many varieties. Current state-of-the-art cathodes demonstrate voltages beyond any known electrolyte stability window, bringing electrolyte research once again to the forefront of battery research

  6. Cathode materials review

    Science.gov (United States)

    Daniel, Claus; Mohanty, Debasish; Li, Jianlin; Wood, David L.

    2014-06-01

    The electrochemical potential of cathode materials defines the positive side of the terminal voltage of a battery. Traditionally, cathode materials are the energy-limiting or voltage-limiting electrode. One of the first electrochemical batteries, the voltaic pile invented by Alessandro Volta in 1800 (Phil. Trans. Roy. Soc. 90, 403-431) had a copper-zinc galvanic element with a terminal voltage of 0.76 V. Since then, the research community has increased capacity and voltage for primary (nonrechargeable) batteries and round-trip efficiency for secondary (rechargeable) batteries. Successful secondary batteries have been the lead-acid with a lead oxide cathode and a terminal voltage of 2.1 V and later the NiCd with a nickel(III) oxide-hydroxide cathode and a 1.2 V terminal voltage. The relatively low voltage of those aqueous systems and the low round-trip efficiency due to activation energies in the conversion reactions limited their use. In 1976, Wittingham (J. Electrochem. Soc., 123, 315) and Besenhard (J. Power Sources 1(3), 267) finally enabled highly reversible redox reactions by intercalation of lithium ions instead of by chemical conversion. In 1980, Goodenough and Mizushima (Mater. Res. Bull. 15, 783-789) demonstrated a high-energy and high-power LiCoO2 cathode, allowing for an increase of terminal voltage far beyond 3 V. Over the past four decades, the international research community has further developed cathode materials of many varieties. Current state-of-the-art cathodes demonstrate voltages beyond any known electrolyte stability window, bringing electrolyte research once again to the forefront of battery research.

  7. Method for sizing hollow microspheres

    Science.gov (United States)

    Farnum, E.H.; Fries, R.J.

    1975-10-29

    Hollow Microspheres may be effectively sized by placing them beneath a screen stack completely immersed in an ultrasonic bath containing a liquid having a density at which the microspheres float and ultrasonically agitating the bath.

  8. Solvothermal synthesis and electrochemical performance of hollow LiFePO{sub 4} nanoparticles

    Energy Technology Data Exchange (ETDEWEB)

    Zheng, Zhenmiao [School of Chemistry and Chemical Engineering, Central South University, Changsha 410083 (China); Pang, Wei Kong [Institute for Superconducting and Electronic Materials, University of Wollongong, Wollongong, NSW 2522 (Australia); Australian Nuclear Science and Technology Organization, Locked Bag 2001, Kirrawee DC, NSW 2232 (Australia); Tang, Xincun, E-mail: tangxincun@163.com [School of Chemistry and Chemical Engineering, Central South University, Changsha 410083 (China); Jia, Dianzeng; Huang, Yudai [Institute of Applied Chemistry, Xinjiang University, Urumqi 840046 (China); Guo, Zaiping [Institute for Superconducting and Electronic Materials, University of Wollongong, Wollongong, NSW 2522 (Australia)

    2015-08-15

    Highlights: • Hollow LiFePO{sub 4} nanoparticles were successfully synthesized via solvothermal method. • The shorter b lattice parameter allows the shorter diffusion path of lithium ion. • Hollow LiFePO{sub 4} nanoparticles show better rate capability than solid LiFePO{sub 4}. - Abstract: Hollow LiFePO{sub 4} nanoparticles were synthesized via a solvothermal technique, using ammonium tartrate as additive and carbon source, and ethylene glycol/water as solvent. The as-prepared samples were characterized by X-ray diffraction, Fourier-transform infrared spectroscopy, Raman spectroscopy, scanning and transmission electron microscopies, and Brunauer–Emmett–Teller specific surface area measurements. The electrochemical properties of the LiFePO{sub 4} cathode were examined in coin-type cell configuration and the cathode exhibited excellent rate capability (i.e., discharge capacity of 120.9 mA h g{sup −1} at 10 C) and cycling performance (i.e., >98% of capacity retention rate after 50 cycles). It is believed that the enhanced performance is correlated to the hollow structure, small crystallite and particle sizes, and relatively shorter lattice parameter b.

  9. Filtered cathodic arc source

    International Nuclear Information System (INIS)

    Falabella, S.; Sanders, D.M.

    1994-01-01

    A continuous, cathodic arc ion source coupled to a macro-particle filter capable of separation or elimination of macro-particles from the ion flux produced by cathodic arc discharge is described. The ion source employs an axial magnetic field on a cathode (target) having tapered sides to confine the arc, thereby providing high target material utilization. A bent magnetic field is used to guide the metal ions from the target to the part to be coated. The macro-particle filter consists of two straight solenoids, end to end, but placed at 45 degree to one another, which prevents line-of-sight from the arc spot on the target to the parts to be coated, yet provides a path for ions and electrons to flow, and includes a series of baffles for trapping the macro-particles. 3 figures

  10. Electromagnetic radiation-2450 MHz exposure causes cognition ...

    Indian Academy of Sciences (India)

    83

    Electromagnetic radiation-2450 MHz exposure causes cognition deficit with mitochondrial. 1 ... decrease in levels of acetylcholine, and increase in activity of acetyl ...... neuronal apoptosis and cognitive disturbances in sevoflurane or propofol ...

  11. Providing primary standard calibrations beyond 20 MHz

    International Nuclear Information System (INIS)

    Bickley, C J; Zeqiri, B; Robinson, S P

    2004-01-01

    The number of applications of medical ultrasound utilising frequencies in excess of 20 MHz has shown a consistent increase over recent years. Coupled with the commercial availability of wide-bandwidth hydrophones whose response extends beyond 40 MHz, this has driven a growing need to develop hydrophone calibration techniques at elevated frequencies. The current National Physical Laboratory primary standard method of calibrating hydrophones is based on an optical interferometer. This has been in operation for around 20 years and provides traceability over the frequency range of 0.3 to 20 MHz. More recently, calibrations carried out using the interferometer have been extended to 60 MHz, although the uncertainties associated with these calibrations are poor, being in excess of ±20% at high frequencies. Major contributions to the degraded calibration uncertainties arise from poor signal-to-noise at higher frequencies, the frequency response of the photodiodes used and the noise floor of the instrument. To improve the uncertainty of hydrophone calibrations above 20 MHz, it has been necessary to build and commission a new interferometer. Important features of the new primary standard are its use of a higher power laser to improve the signal-to-noise ratio, along with photodiodes whose greater bandwidth to improve the overall frequency response. This paper describes the design of key aspects of the new interferometer. It also presents some initial results of the performance assessment, including a detailed comparison of calibrations of NPL reference membrane hydrophones, undertaken using old and new interferometers for calibration up to 40 MHz

  12. Cathode material for lithium batteries

    Science.gov (United States)

    Park, Sang-Ho; Amine, Khalil

    2013-07-23

    A method of manufacture an article of a cathode (positive electrode) material for lithium batteries. The cathode material is a lithium molybdenum composite transition metal oxide material and is prepared by mixing in a solid state an intermediate molybdenum composite transition metal oxide and a lithium source. The mixture is thermally treated to obtain the lithium molybdenum composite transition metal oxide cathode material.

  13. Switching a Nanocluster Core from Hollow to Non-hollow

    KAUST Repository

    Bootharaju, Megalamane Siddaramappa

    2016-03-24

    Modulating the structure-property relationship in atomically precise nanoclusters (NCs) is vital for developing novel NC materials and advancing their applications. While promising biphasic ligand-exchange (LE) strategies have been developed primarily to attain novel NCs, understanding the mechanistic aspects involved in tuning the core and the ligand-shell of NCs in such biphasic processes is challenging. Here, we design a single phase LE process that enabled us to elucidate the mechanism of how a hollow NC (e.g., [Ag44(SR)30]4-, -SR: thiolate) converts into a non-hollow NC (e.g., [Ag25(SR)18]-), and vice versa. Our study reveals that the complete LE of the hollow [Ag44(SPhF)30]4- NCs (–SPhF: 4-fluorobenzenethiolate) with incoming 2,4-dimethylbenzenethiol (HSPhMe2) induced distortions in the Ag44 structure forming the non-hollow [Ag25(SPhMe2)18]- by a disproportionation mechanism. While the reverse reaction of [Ag25(SPhMe2)18]- with HSPhF prompted an unusual dimerization of Ag25, followed by a rearrangement step that reproduces the original [Ag44(SPhF)30]4-. Remarkably, both the forward and the backward reactions proceed through similar size intermediates that seem to be governed by the boundary conditions set by the thermodynamic and electronic stability of the hollow and non-hollow metal cores. Furthermore, the resizing of NCs highlights the surprisingly long-range effect of the ligands which are felt by atoms far deep in the metal core, thus opening a new path for controlling the structural evolution of nanoparticles.

  14. The Electrospun Ceramic Hollow Nanofibers

    Directory of Open Access Journals (Sweden)

    Shahin Homaeigohar

    2017-11-01

    Full Text Available Hollow nanofibers are largely gaining interest from the scientific community for diverse applications in the fields of sensing, energy, health, and environment. The main reasons are: their extensive surface area that increases the possibilities of engineering, their larger accessible active area, their porosity, and their sensitivity. In particular, semiconductor ceramic hollow nanofibers show greater space charge modulation depth, higher electronic transport properties, and shorter ion or electron diffusion length (e.g., for an enhanced charging–discharging rate. In this review, we discuss and introduce the latest developments of ceramic hollow nanofiber materials in terms of synthesis approaches. Particularly, electrospinning derivatives will be highlighted. The electrospun ceramic hollow nanofibers will be reviewed with respect to their most widely studied components, i.e., metal oxides. These nanostructures have been mainly suggested for energy and environmental remediation. Despite the various advantages of such one dimensional (1D nanostructures, their fabrication strategies need to be improved to increase their practical use. The domain of nanofabrication is still advancing, and its predictable shortcomings and bottlenecks must be identified and addressed. Inconsistency of the hollow nanostructure with regard to their composition and dimensions could be one of such challenges. Moreover, their poor scalability hinders their wide applicability for commercialization and industrial use.

  15. Smart cathodic protection systems

    NARCIS (Netherlands)

    Polder, R.B.; Leggedoor, J.; Schuten, G.; Sajna, S.; Kranjc, A.

    2010-01-01

    Cathodic protection delivers corrosion protection in concrete structures exposed to aggressive environments, e.g. in de-icing salt and marine climates. Working lives of a large number of CP systems are at least more than 13 years and probably more than 25 years, provided a minimum level of

  16. The Riddle of the Apparently Hollow Himalaya

    Indian Academy of Sciences (India)

    The Riddle of the Apparently Hollow Himalaya. Ramesh .... It was as if the Himalayas were hollow inside. ... block would be consistent with the ground elevation in such a ... Alternative models and possible preference: Many refinements of.

  17. Hollow nanotubular toroidal polymer microrings.

    Science.gov (United States)

    Lee, Jiyeong; Baek, Kangkyun; Kim, Myungjin; Yun, Gyeongwon; Ko, Young Ho; Lee, Nam-Suk; Hwang, Ilha; Kim, Jeehong; Natarajan, Ramalingam; Park, Chan Gyung; Sung, Wokyung; Kim, Kimoon

    2014-02-01

    Despite the remarkable progress made in the self-assembly of nano- and microscale architectures with well-defined sizes and shapes, a self-organization-based synthesis of hollow toroids has, so far, proved to be elusive. Here, we report the synthesis of polymer microrings made from rectangular, flat and rigid-core monomers with anisotropically predisposed alkene groups, which are crosslinked with each other by dithiol linkers using thiol-ene photopolymerization. The resulting hollow toroidal structures are shape-persistent and mechanically robust in solution. In addition, their size can be tuned by controlling the initial monomer concentrations, an observation that is supported by a theoretical analysis. These hollow microrings can encapsulate guest molecules in the intratoroidal nanospace, and their peripheries can act as templates for circular arrays of metal nanoparticles.

  18. Hollow fiber liquid supported membranes

    International Nuclear Information System (INIS)

    Violante, V.

    1987-01-01

    The hollow fiber system are well known and developed in the scientific literature because of their applicability in the process separation units. The authors approach to a mathematical model for a particular hollow fiber system, usin liquid membranes. The model has been developed in order to obtain a suitable tool for a sensitivy analysis and for a scaling-up. This kind of investigation is very usefull from an engineering point of view, to get a spread range of information to build up a pilot plant from the laboratory scale

  19. Air cathode structure manufacture

    Science.gov (United States)

    Momyer, William R.; Littauer, Ernest L.

    1985-01-01

    An improved air cathode structure for use in primary batteries and the like. The cathode structure includes a matrix active layer, a current collector grid on one face of the matrix active layer, and a porous, nonelectrically conductive separator on the opposite face of the matrix active layer, the collector grid and separator being permanently bonded to the matrix active layer. The separator has a preselected porosity providing low IR losses and high resistance to air flow through the matrix active layer to maintain high bubble pressure during operation of the battery. In the illustrated embodiment, the separator was formed of porous polypropylene. A thin hydrophobic film is provided, in the preferred embodiment, on the current collecting metal grid.

  20. Cathode ray tube screens

    International Nuclear Information System (INIS)

    Cockayne, B.; Robbins, D.J.; Glasper, J.L.

    1982-01-01

    An improved cathode ray tube screen is described which consists of a single- or a poly-crystalline slice of a material such as yttrium aluminium garnet in which dopants such as Tb 3 + , Eu 3 + , Ce 3 + or Tm 3 + are ion implanted to different depths or in different areas of the screen. Annealing the screen removes lattice damage caused by the ion implanting and assists the diffusion of the dopant into the crystal. (U.K.)

  1. Arc cathode spots

    International Nuclear Information System (INIS)

    Schrade, H.O.

    1989-01-01

    Arc spots are usually highly unstable and jump statistically over the cathode surface. In a magnetic field parallel to the surface, preferably they move in the retrograde direction; i.e., opposite to the Lorentzian rule. If the field is inclined with respect to the surface, the spots drift away at a certain angle with respect to the proper retrograde direction (Robson drift motion). These well-known phenomena are explained by one stability theory

  2. Cathode ray tube

    International Nuclear Information System (INIS)

    1979-01-01

    A cathode ray tube comprises two electron lens means in combination to crossover the electron beam at a second crossover between the two electron lens means with one of the two lens means having a variable voltage applied thereto to control the location of the beam crossover in order to focus the beam onto a display screen at any location away from the screen center. (Auth.)

  3. Hollow waveguide cavity ringdown spectroscopy

    Science.gov (United States)

    Dreyer, Chris (Inventor); Mungas, Greg S. (Inventor)

    2012-01-01

    Laser light is confined in a hollow waveguide between two highly reflective mirrors. This waveguide cavity is used to conduct Cavity Ringdown Absorption Spectroscopy of loss mechanisms in the cavity including absorption or scattering by gases, liquid, solids, and/or optical elements.

  4. Hollow core plasma channel generation

    International Nuclear Information System (INIS)

    Quast, Heinrich Martin

    2018-03-01

    The use of a hollow plasma channel in plasma-based acceleration has beneficial properties for the acceleration of electron and positron bunches. In the scope of the FLASHForward facility at DESY, the generation of such a plasma structure is examined. Therefore, the generation of a ring-shaped laser intensity profile with different techniques is analyzed. From the obtained intensity profiles the electron density of a hollow plasma channel is simulated in the focal region. Different parameters are scanned to understand their influence on the electron density distribution - an important parameter being, for example, the radius of the central region of the channel. In addition to the simulations, experiments are presented, during which a laser pulse is transformed into a hollow beam with a spiral phase plate. Subsequently, it forms a plasma during the interaction with hydrogen, where the plasma is imaged with interferometry. For energies above 0.9 mJ a hollow plasma structure can be observed at the location of first plasma formation.

  5. The Legend of Sleepy Hollow

    Institute of Scientific and Technical Information of China (English)

    Washington; Irving

    1987-01-01

    Part Ⅰ On the Eastern shore of the Hudson River there was a little valley, among high hills, which was one of the quietest places in the whole world. This little valley had long been known by the name of SIeepy Hollow. Many strange stories about ghosts were told and retold in the village situated there.

  6. Microstructured hollow fibers for ultrafiltration

    NARCIS (Netherlands)

    Culfaz, Pmar Zeynep; Culfaz, P.Z.; Rolevink, Hendrikus H.M.; van Rijn, C.J.M.; Lammertink, Rob G.H.; Wessling, Matthias

    2010-01-01

    Hollow fiber ultrafiltration membranes with a corrugated outer microstructure were prepared from a PES/PVP blend. The effect of spinning parameters such as air gap, take-up speed, polymer dope viscosity and coagulation value on the microstructure and membrane characteristics was investigated. Fibers

  7. BLAZAR SPECTRAL PROPERTIES AT 74 MHz

    Energy Technology Data Exchange (ETDEWEB)

    Massaro, F.; Funk, S. [SLAC National Laboratory and Kavli Institute for Particle Astrophysics and Cosmology, 2575 Sand Hill Road, Menlo Park, CA 94025 (United States); Giroletti, M. [INAF Istituto di Radioastronomia, via Gobetti 101, I-40129 Bologna (Italy); Paggi, A.; D' Abrusco, R. [Harvard-Smithsonian Astrophysical Observatory, 60 Garden Street, Cambridge, MA 02138 (United States); Tosti, G. [Dipartimento di Fisica, Università degli Studi di Perugia, I-06123 Perugia (Italy)

    2013-10-01

    Blazars are the most extreme class of active galactic nuclei. Despite a previous investigation at 102 MHz for a small sample of BL Lac objects and our recent analysis of blazars detected in the Westerbork Northern Sky Survey, a systematic study of the blazar spectral properties at frequencies below 100 MHz has been never carried out. In this paper, we present the first analysis of the radio spectral behavior of blazars based on the recent Very Large Array Low-frequency Sky Survey (VLSS) at 74 MHz. We search for blazar counterparts in the VLSS catalog, confirming that they are detected at 74 MHz. We then show that blazars present radio-flat spectra (i.e., radio spectral indices of ∼0.5) when evaluated, which also about an order of magnitude in frequency lower than previous analyses. Finally, we discuss the implications of our findings in the context of the blazars-radio galaxies connection since the low-frequency radio data provide a new diagnostic tool to verify the expectations of the unification scenario for radio-loud active galaxies.

  8. Depression cathode structure for cathode ray tubes having surface smoothness and method for producing same

    International Nuclear Information System (INIS)

    Rychlewski, T.V.

    1984-01-01

    Depression cathode structures for cathode ray tubes are produced by dispensing liquid cathode material into the depression of a metallic supporting substrate, removing excess cathode material by passing a doctor blade across the substrate surface and over the depression, and drying the cathode layer to a substantially immobile state. The cathode layer may optionally be further shaped prior to substantially complete drying thereof

  9. Operational features and air plasma characteristics of a thermal plasma torch with hollow electrodes

    International Nuclear Information System (INIS)

    Hur, Min; Kim, Keun Su; Hong, Sang Hee

    2003-01-01

    The operational features and thermal plasma characteristics of a plasma torch with hollow electrodes are investigated based on their dependence on input current, gas flow rate and electrode diameter when air is used as a plasma gas. A plasma torch with a hollow cathode and anode has been designed and fabricated, and the arc voltages and thermal efficiencies are measured from its discharge. The newly modified similarity criteria are derived from the measured data related to torch performances. From the fact that these criteria successfully describe both the arc voltage and thermal efficiency behaviour of the torch, depending on its operating and geometrical parameters, it is proved that they can be usefully applied to the design and operation of high power torches. For the numerical modelling of the interior region of the torch, a cold flow analysis is employed along with a simplified balance equation of the Lorentz and gas dynamic drag forces in order to determine a cathode spot position on the cathode surface. The validity of this method is confirmed by comparison of the calculated and measured net powers. As a practically useful result of this analysis, carried out through this numerical and experimental work, it is suggested that low input current, high gas flow rate and relatively large electrode diameter are more favourable as appropriate operating conditions of the torch for the efficient treatment of hazardous organic wastes

  10. Erythrocyte-like hollow carbon capsules and their application in proton exchange membrane fuel cells.

    Science.gov (United States)

    Kim, Jung Ho; Yu, Jong-Sung

    2010-12-14

    Hierarchical nanostructured erythrocyte-like hollow carbon (EHC) with a hollow hemispherical macroporous core of ca. 230 nm in diameter and 30-40 nm thick mesoporous shell was synthesized and explored as a cathode catalyst support in a proton exchange membrane fuel cell (PEMFC). The morphology control of EHC was successfully achieved using solid core/mesoporous shell (SCMS) silica template and different styrene/furfuryl alcohol mixture compositions by a nanocasting method. The EHC-supported Pt (20 wt%) cathodes prepared have demonstrated markedly enhanced catalytic activity towards oxygen reduction reactions (ORRs) and greatly improved PEMFC polarization performance compared to carbon black Vulcan XC-72 (VC)-supported ones, probably due to the superb structural characteristics of the EHC such as uniform size, well-developed porosity, large specific surface area and pore volume. In particular, Pt/EHC cathodes exhibited ca. 30-60% higher ORR activity than a commercial Johnson Matthey Pt catalyst at a low catalyst loading of 0.2 mg Pt cm(-2).

  11. Barium Depletion in the NSTAR Discharge Cathode After 30,000 Hours of Operation

    Science.gov (United States)

    Polk, James E.; Capece, Angela M.; Mikellides, Ioannis G.; Katz, Ira

    2010-01-01

    Dispenser hollow cathodes rely on a consumable supply of barium released by impregnant materials in the pores of a tungsten matrix to maintain a low work function surface. Examinations of cathode inserts from long duration ion engine tests show deposits of tungsten at the downstream end that appear to block the flow of barium from the interior. In addition, a numerical model of barium transport in the insert plasma indicates that the barium partial pressure in the insert may exceed the equilibrium vapor pressure of the dominant barium-producing reaction, and it was postulated previously that this would suppress barium loss in the upstream part of the insert. New measurements of the depth of barium depletion from a cathode insert operated for 30,352 hours reveal that barium loss is confined to a narrow region near the downstream end, confirming this hypothesis.

  12. Fabrication of Metallic Hollow Nanoparticles

    Science.gov (United States)

    Kim, Jae-Woo (Inventor); Choi, Sr., Sang H. (Inventor); Lillehei, Peter T. (Inventor); Chu, Sang-Hyon (Inventor); Park, Yeonjoon (Inventor); King, Glen C. (Inventor); Elliott, James R. (Inventor)

    2016-01-01

    Metal and semiconductor nanoshells, particularly transition metal nanoshells, are fabricated using dendrimer molecules. Metallic colloids, metallic ions or semiconductors are attached to amine groups on the dendrimer surface in stabilized solution for the surface seeding method and the surface seedless method, respectively. Subsequently, the process is repeated with additional metallic ions or semiconductor, a stabilizer, and NaBH.sub.4 to increase the wall thickness of the metallic or semiconductor lining on the dendrimer surface. Metallic or semiconductor ions are automatically reduced on the metallic or semiconductor nanoparticles causing the formation of hollow metallic or semiconductor nanoparticles. The void size of the formed hollow nanoparticles depends on the dendrimer generation. The thickness of the metallic or semiconductor thin film around the dendrimer depends on the repetition times and the size of initial metallic or semiconductor seeds.

  13. Nanostructured lanthanum manganate composite cathode

    DEFF Research Database (Denmark)

    Wang, Wei Guo; Liu, Yi-Lin; Barfod, Rasmus

    2005-01-01

    that the (La1-xSrx)(y)MnO3 +/-delta (LSM) composite cathodes consist of a network of homogenously distributed LSM, yttria-stabilized zirconia (YSZ), and pores. The individual grain size of LSM or YSZ is approximately 100 nm. The degree of contact between cathode and electrolyte is 39% on average. (c) 2005...

  14. Space Charge Mitigation With Longitudinally Hollow Bunches

    CERN Multimedia

    Oeftiger, Adrian; Rumolo, Giovanni

    2016-01-01

    Hollow longitudinal phase space distributions have a flat profile and hence reduce the impact of transverse space charge. Dipolar parametric excitation with the phase loop feedback systems provides such hollow distributions under reproducible conditions. We present a procedure to create hollow bunches during the acceleration ramp of CERN’s PS Booster machine with minimal changes to the operational cycle. The improvements during the injection plateau of the downstream Proton Synchrotron are assessed in comparison to standard parabolic bunches.

  15. Method to fabricate hollow microneedle arrays

    Energy Technology Data Exchange (ETDEWEB)

    Kravitz, Stanley H [Placitas, NM; Ingersoll, David [Albuquerque, NM; Schmidt, Carrie [Los Lunas, NM; Flemming, Jeb [Albuquerque, NM

    2006-11-07

    An inexpensive and rapid method for fabricating arrays of hollow microneedles uses a photoetchable glass. Furthermore, the glass hollow microneedle array can be used to form a negative mold for replicating microneedles in biocompatible polymers or metals. These microneedle arrays can be used to extract fluids from plants or animals. Glucose transport through these hollow microneedles arrays has been found to be orders of magnitude more rapid than natural diffusion.

  16. Designing a fractal antenna of 2400 MHz

    International Nuclear Information System (INIS)

    Miranda Hamburger, Fabio

    2012-01-01

    The design of a fractal antenna with 2400 MHz of frequency has been studied. The fractal used is described by Waclaw Spierpi.ski. The initial figure, also known as seed, is divided using equilateral triangles with the aim of obtaining a perimeter similar to a meaningful portion of wave length. The use of λ to establish an ideal perimeter has reduced the radiation resistance. The adequate number of iterations needed to design the antenna is calculated based on λ. (author) [es

  17. Design of 325 MHz spoke cavity

    International Nuclear Information System (INIS)

    Sha Peng; Huang Hong; Dai Jianping; Zu Guoquan; Li Han

    2012-01-01

    Spoke cavity can be used in the low-energy section of the proton accelerator. It has many significant advantages: compact structure, high value of R/Q, etc. The ADS (Accelerator Driven System) project will adopt many spoke cavities with different β values. Therefore, IHEP has began the research of β=0.14, 325 MHz spoke cavity. In this pa per, the dimensions, RF performances and mechanical properties of it are studied. (authors)

  18. Efficient Overall Water-Splitting Electrocatalysis Using Lepidocrocite VOOH Hollow Nanospheres

    KAUST Repository

    Shi, Huanhuan

    2016-11-29

    Herein we report the control synthesis of lepidocrocite VOOH hollow nanospheres and further their applications in electrocatalytic water splitting for the first time. By tuning the surface area of the nanospheres, the optimal performance can be achieved with low overpotentials of 270 mV for the oxygen evolution reaction (OER) and 164 mV for the hydrogen evolution reaction (HER) at 10 mA cm-2 in 1 m KOH, respectively. Furthermore, when used as both the anode and cathode for overall water splitting, a low cell voltage of 1.62 V is required to reach the current density of 10 mA cm-2 , making the VOOH hollow nanospheres an efficient alternative to water splitting.

  19. Electrochemically Active Polymeric Hollow Fibers based on Poly(ether- b -amide)/Carbon Nanotubes

    KAUST Repository

    Cuevas, Carolina

    2017-09-18

    A simple and effective method to incorporate catalytic activity to a hollow fiber membrane is reported. Polyetherimide hollow fiber membranes were coated with a solution containing carboxyl-functionalized multi-walled carbon nanotubes and poly(ether-b-amide). Electron microscopy images confirmed the presence of a layer of percolating carbon nanotubes on the surface of the membranes. Cyclic voltammetry and linear swept voltammetry experiments showed that these membranes are able to drive the reactions of hydrogen evolution, and oxygen reduction, making them a cheaper, and greener substitute for platinum based cathodes in microbial bioelectrochemical systems. Water flux and molecular weight cut off experiments indicated that the electrochemically active coating layer does not affect the ultrafiltration performance of the membrane.

  20. Electrochemically Active Polymeric Hollow Fibers based on Poly(ether- b -amide)/Carbon Nanotubes

    KAUST Repository

    Cuevas, Carolina; Kim, Dooli; Katuri, Krishna; Saikaly, Pascal; Nunes, Suzana Pereira

    2017-01-01

    A simple and effective method to incorporate catalytic activity to a hollow fiber membrane is reported. Polyetherimide hollow fiber membranes were coated with a solution containing carboxyl-functionalized multi-walled carbon nanotubes and poly(ether-b-amide). Electron microscopy images confirmed the presence of a layer of percolating carbon nanotubes on the surface of the membranes. Cyclic voltammetry and linear swept voltammetry experiments showed that these membranes are able to drive the reactions of hydrogen evolution, and oxygen reduction, making them a cheaper, and greener substitute for platinum based cathodes in microbial bioelectrochemical systems. Water flux and molecular weight cut off experiments indicated that the electrochemically active coating layer does not affect the ultrafiltration performance of the membrane.

  1. Heat transfer enhancement using 2MHz ultrasound.

    Science.gov (United States)

    Bulliard-Sauret, Odin; Ferrouillat, Sebastien; Vignal, Laure; Memponteil, Alain; Gondrexon, Nicolas

    2017-11-01

    The present work focuses on possible heat transfer enhancement from a heating plate towards tap water in forced convection by means of 2MHz ultrasound. The thermal approach allows to observe the increase of local convective heat transfer coefficients in the presence of ultrasound and to deduce a correlation between ultrasound power and Nusselt number. Heat transfer coefficient under ultrasound remains constant while heat transfer coefficient under silent conditions increases with Reynolds number from 900 up to 5000. Therefore, heat transfer enhancement factor ranges from 25% up to 90% for the same energy conditions (supplied ultrasonic power=110W and supplied thermal power=450W). In the same time cavitational activity due to 2MHz ultrasound emission was characterized from mechanical and chemical viewpoints without significant results. At least, Particle Image Velocimetry (PIV) measurements have been performed in order to investigate hydrodynamic modifications due to the presence of 2MHz ultrasound. It was therefore possible to propose a better understanding of heat transfer enhancement mechanism with high frequency ultrasound. Copyright © 2017 Elsevier B.V. All rights reserved.

  2. Modified Gold Electrode and Hollow Mn3O4 Nanoparticles as Electrode Materials for Microbial Fuel Cell Applications

    Science.gov (United States)

    Dhungana, Pramod

    Microbial fuel cell (MFC) technology has attracted great attention in the scientific community as it offers the possibility of extraction of electricity from wide range of soluble and dissolved organic waste or renewable biomass, including sludge, waste water and cellulosic biomass. Microbial fuel cells are devices that utilize microbial metabolic processes to convert chemical energy via the oxidation of organic substances to produce electric current. MFCs consist of two chambers, an anode and cathode, separated by ion-permeable materials. The efficiency of producing electricity using the MFC depends on several factors such as immobilization of microorganisms on anode, mode of electron transfer, types of substrate/fuel and effectiveness of cathode materials for oxygen reduction reaction (ORR). In this work, in order to immobilize the microorganisms on anode materials, we have investigated the surface modification of gold electrode (anode) using alkyl dithiol and aryl thiol with glucose. The modification processes were characterized by using contact angle measurements and proton nuclear magnetic resonance (NMR). In order to study the effectiveness of cathode materials for ORR, we have synthesized hollow Mn3O 4 nanoparticles which are electrically very poor. Therefore, the hollow nanoparticles were mixed with electrically conductive multi-walled carbon nanotube as support and optimized the mixing process. This composite material shows enhanced ORR activity in all types of pH conditions. In future, we will focus to integrate anode and cathode in MFC to check its efficiency to produce electricity.

  3. Materials characterization of impregnated W and W–Ir cathodes after oxygen poisoning

    International Nuclear Information System (INIS)

    Polk, James E.; Capece, Angela M.

    2015-01-01

    Highlights: • Impregnated W and W–Ir cathodes were operated with 100 ppm of oxygen in Xe gas. • High concentrations of oxygen accelerated the formation of tungstate layers. • The W–Ir emitter exhibited less erosion and redeposition at the upstream end. • Tungsten was preferentially transported in the insert plasma of the W–Ir cathode. - Abstract: Electric thrusters use hollow cathodes as the electron source for generating the plasma discharge and for beam neutralization. These cathodes contain porous tungsten emitters impregnated with BaO material to achieve a lower surface work function and are operated with xenon propellant. Oxygen contaminants in the xenon plasma can poison the emitter surface, resulting in a higher work function and increased operating temperature. This could lead directly to cathode failure by preventing discharge ignition or could accelerate evaporation of the BaO material. Exposures over hundreds of hours to very high levels of oxygen can result in increased temperatures, oxidation of the tungsten substrate, and the formation of surface layers of barium tungstates. In this work, we present results of a cathode test in which impregnated tungsten and tungsten–iridium emitters were operated with 100 ppm of oxygen in the xenon plasma for several hundred hours. The chemical and morphological changes were studied using scanning electron microscopy, energy dispersive spectroscopy, and laser profilometry. The results provide strong evidence that high concentrations of oxygen accelerate the formation of tungstate layers in both types of emitters, a phenomenon not inherent to normal cathode operation. Deposits of pure tungsten were observed on the W–Ir emitter, indicating that tungsten is preferentially removed from the surface and transported in the insert plasma. A W–Ir cathode surface will therefore evolve to a pure W composition, eliminating the work function benefit of W–Ir. However, the W–Ir emitter exhibited less erosion

  4. 47 CFR 90.355 - LMS operations below 512 MHz.

    Science.gov (United States)

    2010-10-01

    ... PRIVATE LAND MOBILE RADIO SERVICES Intelligent Transportation Systems Radio Service § 90.355 LMS... LMS station and the nearest co-channel base station of another licensee operating a voice system is 75... MHz, 150-170 MHz, and 450-512 MHz bands may use either base-mobile frequencies currently assigned the...

  5. Electron emission from pseudospark cathodes

    International Nuclear Information System (INIS)

    Anders, A.; Anders, S.; Gundersen, M.A.

    1994-01-01

    The pseudospark cathode has the remarkable property of macroscopically homogeneous electron emission at very high current density (>1 kA/cm 2 ) over a large area (some cm 2 ). The model of electron emission presented here is based on the assumption that the pseudospark microscopically utilizes explosive arc processes, as distinct from earlier models of ''anomalous emission in superdense glow discharges.'' Explosive emission similar to vacuum are cathode spots occurs rapidly when the field strength is sufficiently high. The plasma remains macroscopically homogeneous since the virtual plasma anode adapts to the cathode morphology so that the current is carried by a large number of homogeneously distributed cathode spots which are similar to ''type 1'' and ''type 2'' spots of vacuum arc discharges. The net cathode erosion is greatly reduced relative to ''spark gap-type'' emission. At very high current levels, a transition to highly erosive spot types occurs, and this ''arcing'' leads to a significant reduction in device lifetime. Assuming vacuum-arc-like cathode spots, the observed current density and time constants can be easily explained. The observed cathode erosion rate and pattern, recent fast-camera data, laser-induced fluorescence, and spectroscopic measurements support this approach. A new hypothesis is presented explaining current quenching at relatively low currents. From the point of view of electron emission, the ''superdense glow'' or ''superemissive phase'' of pseudosparks represents an arc and not a glow discharge even if no filamentation or ''arcing'' is observed

  6. Hollow nanocrystals and method of making

    Science.gov (United States)

    Alivisatos, A Paul [Oakland, CA; Yin, Yadong [Moreno Valley, CA; Erdonmez, Can Kerem [Berkeley, CA

    2011-07-05

    Described herein are hollow nanocrystals having various shapes that can be produced by a simple chemical process. The hollow nanocrystals described herein may have a shell as thin as 0.5 nm and outside diameters that can be controlled by the process of making.

  7. 47 CFR 15.242 - Operation in the bands 174-216 MHz and 470-668 MHz.

    Science.gov (United States)

    2010-10-01

    ... 47 Telecommunication 1 2010-10-01 2010-10-01 false Operation in the bands 174-216 MHz and 470-668... bands 174-216 MHz and 470-668 MHz. (a) The marketing and operation of intentional radiators under the... services, facilities, and beds for use beyond 24 hours in rendering medical treatment and institutions and...

  8. Research on an improved explosive emission cathode

    International Nuclear Information System (INIS)

    Liu Guozhi; Sun Jun; Shao Hao; Chen Changhua; Zhang Xiaowei

    2009-01-01

    This paper presents a physical description of the cathode plasma process of an explosive emission cathode (EEC) and experimental results on a type of oil-immersed graphite EEC. It is believed that the generation of a cathode plasma is mainly dependent on the state of the cathode surface, and that adsorbed gases and dielectrics on the cathode surface play a leading role in the formation of the cathode plasma. Based on these ideas, a type of oil-immersed graphite EEC is proposed and fabricated. The experiments indicate that the oil-immersed cathodes have improved emissive properties and longer lifetimes.

  9. Hollow rods for the oil producing industry

    Energy Technology Data Exchange (ETDEWEB)

    Khalimova, L M; Elyasheva, M A

    1970-01-01

    Hollow sucker rods have several advantages over conventional ones. The hollow rods actuate the well pump and at the same time conduct produced fluids to surface. When paraffin deposition occurs, it can be minimized by injecting steam, hot oil or hot water into the hollow rod. Other chemicals, such as demulsifiers, scale inhibitors, corrosion inhibitors, etc., can also be placed in the well through the hollow rods. This reduces cost of preventive treatments, reduces number of workovers, increases oil production, and reduces cost of oil. Because the internal area of the rod is small, the passing liquids have a high velocity and thereby carry sand and dirt out of the well. This reduces pump wear between the piston and the plunger. Specifications of hollow rods, their operating characteristics, and results obtained with such rods under various circumstances are described.

  10. Frequency Arrangement For 700 MHz Band

    Directory of Open Access Journals (Sweden)

    Ancans G.

    2015-02-01

    Full Text Available The 694-790 MHz (700 MHz band was allocated by the 2012 World Radiocommunication Conference (WRC-12 in ITU Region 1 (Europe included, to the mobile service on a co-primary basis with other services to which this band was allocated on the primary basis and identified for the International Mobile Telecommunications (IMT. At the same time, the countries of Region 1 will be able also to continue using these frequencies for their broadcasting services if necessary. This allocation will be effective immediately after 2015 World Radiocommunication Conference (WRC-15. In order to make the best possible use of this frequency band for mobile service, a worldwide harmonized frequency arrangement is to be prepared to allow for large economies of scale and international roaming as well as utilizing the available spectrum in the best possible way, minimizing possible interference between services, facilitating deployment and cross-border coordination. The authors analyze different possible frequency arrangements and conclude on the frequency arrangement most suitable for Europe.

  11. Study of high frequency instabilities on a cold cathode reflex discharge; Contribution a l'etude des instabilites a haute frequence dans la decharge reflex a cathodes froides

    Energy Technology Data Exchange (ETDEWEB)

    Gregoire, M [Commissariat a l' Energie Atomique, Saclay (France). Centre d' Etudes Nucleaires

    1965-06-01

    The cold cathode reflex discharge develops a cathode sheath of several hundreds of volts, which accelerates electrons released from the cathode to high velocities along the lines of the axial magnetic field. On the studied pressure range (4.10{sup -4} torr < p < 2.10{sup -2} torr) the plasma density is about 10{sup 11} cm{sup -3}. Under certain conditions high frequency (1 5000 MHz) instabilities appear. These instabilities are found to profoundly modify the mean characteristics of the discharge. In particular, particle flow across the lines of magnetic field is found to be considerably greater than that predicted by classical diffusion theory. Theoretical considerations are presented with complementary experimental results. They show that the high frequency instabilities are a result of the fast electronic assembly accelerated through the cathode sheath. (author) [French] Dans certaines conditions, qui sont precisees, des instabilites a haute frequence (1 5000 MHz) se developpent dans la decharge reflex a cathodes froides. Lorsque le plasma (n {approx_equal}10{sup 11} cm{sup -3}) est instable, les caracteristiques moyennes de la decharge sont profondement alterees. Les fuites de particules a travers les lignes de forces du champ magnetique statique applique deviennent en particulier trop importantes pour que le seul effet classique des collisions binaires puisse les expliquer. L'ionisation du gaz est assuree par une assemblee electronique qui acquiert dans les gaines cathodiques ({approx_equal} 500 volts) une vitesse, parallele au champ magnetique, importante. La discussion de resultats theoriques et une experience complementaire montrent que cette population d'electrons rapides, tres distincte de celle des electrons lents du plasma pour les pressions les plus faibles du domaine etudie (4.10{sup -4} torr < p < 2.10{sup -2} torr), est responsable des instabilites a haute frequence observees. (auteur)

  12. The 938 MHz resonant damping loops for the 200 MHz SPS travelling wave cavities

    CERN Document Server

    Caspers, F

    2012-01-01

    Measurements of the beam stability in the SPS in 1982 - 1983 have shown a transversal instability for high intensity beams [1]. The fact that this related technical note is published nearly 30 years later, is related to the revival of interest in the frame of SPS impedance evaluation for LS1. Until now there was just a barely known paper folder available which could be consulted on request. The instability mentioned above was identified from beam measurements as raised by a deflecting mode at approximately 940 MHz in the 200 MHz travelling wave cavities of the SPS. Estimates showed that an attenuation of this particular mode by 20 dB would be desirable. In order to achieve this attenuation some vacuum ports on top of the cavities were available. For the damping devices three requirements had to be met: - sufficient damping at about 940 MHz - no serious change of cavity input VSWR at 200 MHz - no water cooling requirement for this higher order mode coupler.

  13. 47 CFR 101.69 - Transition of the 1850-1990 MHz, 2110-2150 MHz, and 2160-2200 MHz bands from the fixed microwave...

    Science.gov (United States)

    2010-10-01

    ..., and 2160-2200 MHz bands from the fixed microwave services to personal communications services and...) SAFETY AND SPECIAL RADIO SERVICES FIXED MICROWAVE SERVICES Applications and Licenses License Transfers... MHz bands from the fixed microwave services to personal communications services and emerging...

  14. Hollow Micro-/Nanostructures: Synthesis and Applications

    KAUST Repository

    Lou, Xiong Wen (David)

    2008-11-03

    Hollow micro-nanostructures are of great interest in many current and emerging areas of technology. Perhaps the best-known example of the former is the use of fly-ash hollow particles generated from coal power plants as partial replacement for Portland cement, to produce concrete with enhanced strength and durability. This review is devoted to the progress made in the last decade in synthesis and applications of hollow micro-nanostructures. We present a comprehensive overview of synthetic strategies for hollow structures. These strategies are broadly categorized into four themes, which include well-established approaches, such as conventional hard-templating and soft-templating methods, as well as newly emerging methods based on sacrificial templating and template-free synthesis. Success in each has inspired multiple variations that continue to drive the rapid evolution of the field. The Review therefore focuses on the fundamentals of each process, pointing out advantages and disadvantages where appropriate. Strategies for generating more complex hollow structures, such as rattle-type and nonspherical hollow structures, are also discussed. Applications of hollow structures in lithium batteries, catalysis and sensing, and biomedical applications are reviewed. © 2008 WILEY-VCH Verlag GmbH & Co. KGaA,.

  15. Method for producing small hollow spheres

    International Nuclear Information System (INIS)

    Hendricks, C.D.

    1979-01-01

    A method is described for producing small hollow spheres of glass, metal or plastic, wherein the sphere material is mixed with or contains as part of the composition a blowing agent which decomposes at high temperature (T >approx. 600 0 C). As the temperature is quickly raised, the blowing agent decomposes and the resulting gas expands from within, thus forming a hollow sphere of controllable thickness. The thus produced hollow spheres (20 to 10 3 μm) have a variety of application, and are particularly useful in the fabrication of targets for laser implosion such as neutron sources, laser fusion physics studies, and laser initiated fusion power plants

  16. Formation of Uniform Hollow Silica microcapsules

    Science.gov (United States)

    Yan, Huan; Kim, Chanjoong

    2013-03-01

    Microcapsules are small containers with diameters in the range of 0.1 - 100 μm. Mesoporous microcapsules with hollow morphologies possess unique properties such as low-density and high encapsulation capacity, while allowing controlled release by permeating substances with a specific size and chemistry. Our process is a one-step fabrication of monodisperse hollow silica capsules with a hierarchical pore structure and high size uniformity using double emulsion templates obtained by the glass-capillary microfluidic technique to encapsulate various active ingredients. These hollow silica microcapsules can be used as biomedical applications such as drug delivery and controlled release.

  17. Microring embedded hollow polymer fiber laser

    Energy Technology Data Exchange (ETDEWEB)

    Linslal, C. L., E-mail: linslal@gmail.com; Sebastian, S.; Mathew, S.; Radhakrishnan, P.; Nampoori, V. P. N.; Girijavallabhan, C. P.; Kailasnath, M. [International School of Photonics, Cochin University of Science and Technology, Cochin 22 (India)

    2015-03-30

    Strongly modulated laser emission has been observed from rhodamine B doped microring resonator embedded in a hollow polymer optical fiber by transverse optical pumping. The microring resonator is fabricated on the inner wall of a hollow polymer fiber. Highly sharp lasing lines, strong mode selection, and a collimated laser beam are observed from the fiber. Nearly single mode lasing with a side mode suppression ratio of up to 11.8 dB is obtained from the strongly modulated lasing spectrum. The microring embedded hollow polymer fiber laser has shown efficient lasing characteristics even at a propagation length of 1.5 m.

  18. BNL 703 MHz SRF cryomodule demonstration

    International Nuclear Information System (INIS)

    Burrill, A.; Ben-Zvi, I.; Calaga, R.; Dalesio, L.; Dottavio, T.; Gassner, D.; Hahn, H.; Hoff, L.; Kayran, D.; Kewisch, J.; Lambiase, R.; Lederle, D.; Litvinenko, V.; Mahler, G.; McIntyre, G.

    2009-01-01

    This paper will present the preliminary results of the testing of the 703 MHz SRF cryomodule designed for use in the ampere class ERL under construction at Brookhaven National Laboratory. The preliminary cavity tests, carried out at Thomas Jefferson Laboratory, demonstrated cavity performance of 20 MV/m with a Qo of 1 x 10 10 , results we expect to reproduce in the horizontal configuration. This test of the entire string assembly will allow us to evaluate all of the additional cryomodule components not previously tested in the VTA and will prepare us for our next milestone test which will be delivery of electrons from our injector through the cryomodule to the beam dump. This will also be the first demonstration of an accelerating cavity designed for use in an ampere class ERL, a key development which holds great promise for future machines

  19. The all-sky 408 MHz survey

    International Nuclear Information System (INIS)

    Haslam, C.G.T.; Salter, C.J.; Stoffel, H.

    1981-01-01

    A brief outline of the results of this survey is presented. The 408 MHz All-sky Survey has been made from four radio continuum surveys observed between 1965 and 1978, using the Jodrell Bank MKI telescope (Haslam et al., 1970), the Effelsberg 100 metre telescope (Haslam et al., 1974) and the Parkes 64 metre telescope (Haslam et al., 1975). A detailed description of the survey data reduction and calibration methods, with preliminary astronomical results will soon be published (Haslam et al., 1980a) and a second paper will give an atlas of maps at the full survey resolution of 51' arc between half power points (Haslam et al., 1980b). A map, smoothed to a gaussian beam with resolution between half power poitns of 3 0 , is presented. (Auth.)

  20. Electron emission mechanism of carbon fiber cathode

    International Nuclear Information System (INIS)

    Liu Lie; Li Limin; Wen Jianchun; Wan Hong

    2005-01-01

    Models of electron emission mechanism are established concerning metal and carbon fiber cathodes. Correctness of the electron emission mechanism was proved according to micro-photos and electron scanning photos of cathodes respectively. The experimental results and analysis show that the surface flashover induces the electron emission of carbon fiber cathode and there are electron emission phenomena from the top of the carbon and also from its side surface. In addition, compared with the case of the stainless steel cathode, the plasma expansion velocity for the carbon fiber cathode is slower and the pulse duration of output microwave can be widened by using the carbon fiber cathode. (authors)

  1. optimizing compressive strength characteristics of hollow building

    African Journals Online (AJOL)

    eobe

    Keywords: hollow building Blocks, granite dust, sand, partial replacement, compressive strength. 1. INTRODUCTION ... exposed to extreme climate. The physical ... Sridharan et al [13] conducted shear strength studies on soil-quarry dust.

  2. Hollow Micro-/Nanostructures: Synthesis and Applications

    KAUST Repository

    Lou, Xiong Wen (David); Archer, Lynden A.; Yang, Zichao

    2008-01-01

    for Portland cement, to produce concrete with enhanced strength and durability. This review is devoted to the progress made in the last decade in synthesis and applications of hollow micro-nanostructures. We present a comprehensive overview of synthetic

  3. Adsorption characteristics of activated carbon hollow fibers

    Directory of Open Access Journals (Sweden)

    B. V. Kaludjerović

    2009-01-01

    Full Text Available Carbon hollow fibers were prepared with regenerated cellulose or polysulfone hollow fibers by chemical activation using sodium phosphate dibasic followed by the carbonization process. The activation process increases the adsorption properties of fibers which is more prominent for active carbone fibers obtained from the cellulose precursor. Chemical activation with sodium phosphate dibasic produces an active carbon material with both mesopores and micropores.

  4. Hollow-duct radiation delivery system investigation

    Directory of Open Access Journals (Sweden)

    Kramer D.

    2013-05-01

    Full Text Available Investigation of hollow-duct structure for high-power laser-diode-array radiation delivery into the end-pumped large-aperture gain media is reported. A ray tracing method has been used to evaluate the performance of the structure designed for maximum transmission efficiency and output beam profile homogeneity. Variable hollow-duct lengths as well as emanating angles of laser-diode-array have been taken into account.

  5. Plasma Deposition of Oxide-Coated Cathodes

    National Research Council Canada - National Science Library

    Umstattd, Ryan

    1998-01-01

    ...; such cathodes may also have applicability for lower current density continuous wave devices. This novel approach to manufacturing an oxide cathode eliminates the binders that may subsequently (and unpredictably...

  6. Mechanistic Enhancement of SOFC Cathode Durability

    Energy Technology Data Exchange (ETDEWEB)

    Wachsman, Eric [Univ. of Maryland, College Park, MD (United States)

    2016-02-01

    Durability of solid oxide fuel cells (SOFC) under “real world” conditions is an issue for commercial deployment. In particular cathode exposure to moisture, CO2, Cr vapor (from interconnects and BOP), and particulates results in long-term performance degradation issues. Here, we have conducted a multi-faceted fundamental investigation of the effect of these contaminants on cathode performance degradation mechanisms in order to establish cathode composition/structures and operational conditions to enhance cathode durability.

  7. Preliminary Design Study of the Hollow Electron Lens for LHC

    CERN Document Server

    Perini, Diego; CERN. Geneva. ATS Department

    2017-01-01

    A Hollow Electron Lens (HEL) has been proposed in order to improve performance of halo control and collimation in the Large Hadron Collider in view of its High Luminosity upgrade (HL-LHC). The concept is based on a beam of electrons that travels around the protons for a few meters. The electron beam is produced by a cathode and then guided by a strong magnetic field generated by a set of superconducting solenoids. The first step of the design is the definition of the magnetic fields that drive the electron trajectories. The estimation of such trajectories by means of a dedicated MATLAB® tool is presented. The influence of the main geometrical and electrical parameters are analysed and discussed. Then, the main mechanical design choices for the solenoids, cryostats gun and collector are described. The aim of this paper is to provide an overview of the preliminary design of the Electron Lens for LHC. The methods used in this study also serve as examples for future mechanical and integration designs of similar ...

  8. 300-MHz optical discriminator-counter

    International Nuclear Information System (INIS)

    Turko, B.; Lo, C.C.

    1981-07-01

    The prediction of future CO 2 content in the atmosphere is not completely credible because the oceanographers and terrestrial ecologists do not agree on the global CO 2 balance. Very precise measurements of O 2 /N 2 ratio using Raman scattering over a few years' period could provide important information and lead to the explanation of the disparity in the atmospheric CO 2 balance. An optical discriminator-counter has been developed to count closely spaced optical events in the few photon level. Simulated optical events as close as 2.5 ns apart had been positively detected by using selected photomultipliers and optimized discriminators. Testing of the optical discriminator-counter was done by using an electrical pulse pair spaced 3 ns apart and also by a similar optical pulse pair generated by fast light-emitting diode. The photomultiplier is capable of counting an average single photoelectron pulse frequency of 50 MHz and has a sensitive detecting area of 50 mm in diameter. The discriminator performance is discussed

  9. 500 MHz transient digitizers based on GaAs CCDs

    International Nuclear Information System (INIS)

    Bryman, D.A.; Constable, M.; Cresswell, J.V.; Daviel, A.; LeNoble, M.; Mildenberger, J.; Poutissou, R.

    1996-11-01

    A system of 500 MHz transient digitizers based on gallium arsenide resistive gate charged coupled devices has been developed for an experiment studying rare K decays. CCDs with dynamic range of 8-bits and 128 or 320 pixels are used as analog pipelines. The CCD's are driven by a single phase transport system. Data readout and manipulation occurs at 15.6 MHz. (authors)

  10. Kerr Hollow Quarry Remediation Project

    International Nuclear Information System (INIS)

    Walker, K.L.

    1993-01-01

    The Kerr Hollow Quarry is a 3-acre flooded limestone quarry located near the Y-12 Facility on the Oak Ridge Reservation. The quarry was used in the 1940s as a source of construction material for the Department of Energy in Oak Ridge, Tennessee. Its use was discontinued in the early 1950s, and it was allowed to flood with water. The quarry presently has a maximum water depth of approximately 55 ft. During the period between the early 1950s until about 1988, the quarry was used for the treatment and disposal of a variety of materials including water-reactive, alkali metals, shock-sensitive chemicals, and compressed gas cylinders. For some of these materials, the treatment consisted of dropping the vessels containing the materials into the quarry from a high bluff located on one side of the quarry. The vessels were then punctured by gun shot, and the materials were allowed to react with the water and sink to the bottom of the quarry. Very few disposal records exist for the period from 1952 to 1962. The records after that time, from 1962 until 1988, indicate some 50 t of hazardous and nonhazardous materials were disposed of in the quarry. This report documents remediation efforts that have taken place at the quarry beginning in September 1990

  11. A 70 MHz pulsing beam system for protons

    International Nuclear Information System (INIS)

    An Shizhong; Zhang Tianjue; Wu Longcheng; Lv Yinlong; Song Guofang; Guan Fengping; Jia Xianlu

    2008-01-01

    A test beam line for pulsed beam generation for 10 MeV central region model (CRM) of a compact cyclotron is under construction as China Institute of Atomic Energy (CIAE). A 70 MHz continuous H - beam with the energy of dozens of keV or a hundred keV will be pulsed to pulse length of less than 10 ns with the repetition rate of 1-8 MHz. A 70.487 MHz buncher will be used to compress the DC beam into the RF phase acceptance of ±30° of the CRM cyclotron. The 2.2 MHz sine waveform will be used for the chopper. A pulse with the repetition rate to 4.4 MHz and pulse length less than 10 ns is expected after CRM cyclotron. (authors)

  12. Imaging melanin cancer growth in-vivo using raster-scan optoacoustic mesoscopy (RSOM) at 50 MHz and 100 MHz

    Science.gov (United States)

    Omar, Murad; Schwarz, Mathias; Soliman, Dominik; Symvoulidis, Panagiotis; Ntziachristos, Vasilis

    2016-03-01

    We used raster-scan optoacoustic mesoscopy (RSOM) at 50 MHz, and at 100 MHz, to monitor tumor growth, and tumor angiogenesis, which is a central hallmark of cancer, in-vivo. In this study we compared the performance, and the effect of the 50 MHz, and the 100 MHz frequencies on the quality of the final image. The system is based on a reflection-mode implementation of RSOM. The detectors used are custom made, ultrawideband, and spherically focused. The use of such detectors enables light coupling from the same side as the detector, thus reflection-mode. Light is in turn coupled using a fiber bundle, and the detector is raster scanned in the xy-plane. Subsequently, to retrieve small features, the raw data are reconstructed using a multi-bandwidth, beamforming reconstruction algorithm. Comparison of the system performance at the different frequencies shows as expected a higher resolution in case of the 100 MHz detector compared to the 50 MHz. On the other hand the 50 MHz has a better SNR, can detect features from deeper layers, and has higher angular acceptance. Based on these characteristics the 50 MHz detector was mostly used. After comparing the performance we monitored the growth of B16F10 cells, melanin tumor, over the course of 9 days. We see correspondence between the optoacoustic measurements and the cryoslice validations. Additionally, in areas close to the tumor we see sprouting of new vessels, starting at day 4-5, which corresponds to tumor angiogenesis.

  13. A study of plasma parameters in hollow cathode plasma jet in pulse regime

    Czech Academy of Sciences Publication Activity Database

    Kudrna, P.; Klusoň, J.; Leshkov, S.; Chichina, M.; Picková, I.; Hubička, Zdeněk; Tichý, M.

    2010-01-01

    Roč. 50, č. 9 (2010), s. 886-891 ISSN 0863-1042 R&D Projects: GA ČR GA202/09/0800 Institutional research plan: CEZ:AV0Z10100522 Keywords : thin-films * system * deposition * RF * nitride Subject RIV: BL - Plasma and Gas Discharge Physics Impact factor: 1.006, year: 2010

  14. Characterization of atomic oxygen in a Hollow Cathode Radio-Frequency Plasma and study its efficiency

    International Nuclear Information System (INIS)

    Naddaf, M.; Saloum, S.

    2011-01-01

    The atomic oxygen (AO) generated in the remote oxygen plasma of the HCD-L300 source, has been fully diagnosed by various conventional techniques. The density of AO was found to vary from (1-10)x10 1 9 m - 3 depending on the operating conditions and parameters. The interaction of the oxygen plasma with silver and gold thin films is investigated by gravimetric analysis, scanning electron microscopy (SEM) and energy dispersive x-ray (EDX) spectroscopy. The effect of AO on surface wetting and energy of polymeric materials is also investigated by using contact angle measurements and analysis technique. From applied point of view, production of super hydrophobic Teflon surface and the significant enhancement in the surface free energy of polyimide and polyamide are considered the most important obtained results in the present work. (author)

  15. Analysis of XeC1 Emission in a Hollow Cathode Discharge.

    Science.gov (United States)

    1981-06-01

    excited homopolar molecule, e.g., Xe2 , Hg2 The term exciplex refers to an electronically excited heteropolar complex, e.g., KrF , XeOH , XeCl , which...frequently overlooked and both homopolar and heteropolar systems are commonly referred to as excimers, Excimers are formed by the interaction between two...mode and a non-scanning mode. Scanning is performed using a 1 rpm motor and produces plots of in- tensity versus wavelength. The non-scanning mode is

  16. Two-stage plasma gun based on a gas discharge with a self-heating hollow emitter.

    Science.gov (United States)

    Vizir, A V; Tyunkov, A V; Shandrikov, M V; Oks, E M

    2010-02-01

    The paper presents the results of tests of a new compact two-stage bulk gas plasma gun. The plasma gun is based on a nonself-sustained gas discharge with an electron emitter based on a discharge with a self-heating hollow cathode. The operating characteristics of the plasma gun are investigated. The discharge system makes it possible to produce uniform and stable gas plasma in the dc mode with a plasma density up to 3x10(9) cm(-3) at an operating gas pressure in the vacuum chamber of less than 2x10(-2) Pa. The device features high power efficiency, design simplicity, and compactness.

  17. Two-stage plasma gun based on a gas discharge with a self-heating hollow emitter

    International Nuclear Information System (INIS)

    Vizir, A. V.; Tyunkov, A. V.; Shandrikov, M. V.; Oks, E. M.

    2010-01-01

    The paper presents the results of tests of a new compact two-stage bulk gas plasma gun. The plasma gun is based on a nonself-sustained gas discharge with an electron emitter based on a discharge with a self-heating hollow cathode. The operating characteristics of the plasma gun are investigated. The discharge system makes it possible to produce uniform and stable gas plasma in the dc mode with a plasma density up to 3x10 9 cm -3 at an operating gas pressure in the vacuum chamber of less than 2x10 -2 Pa. The device features high power efficiency, design simplicity, and compactness.

  18. Synopsis of Cathode No.4 Activation

    International Nuclear Information System (INIS)

    Kwan, Joe; Ekdahl, C.; Harrison, J.; Kwan, J.; Leitner, M.; McCruistian, T.; Mitchell, R.; Prichard, B.; Roy, P.

    2006-01-01

    The purpose of this report is to describe the activation of the fourth cathode installed in the DARHT-II Injector. Appendices have been used so that an extensive amount of data could be included without danger of obscuring important information contained in the body of the report. The cathode was a 612 M type cathode purchased from Spectra-Mat. Section II describes the handling and installation of the cathode. Section III is a narrative of the activation based on information located in the Control Room Log Book supplemented with time plots of pertinent operating parameters. Activation of the cathode was performed in accordance with the procedure listed in Appendix A. The following sections provide more details on the total pressure and constituent partial pressures in the vacuum vessel, cathode heater power/filament current, and cathode temperature

  19. A sulfur host based on titanium monoxide@carbon hollow spheres for advanced lithium-sulfur batteries.

    Science.gov (United States)

    Li, Zhen; Zhang, Jintao; Guan, Buyuan; Wang, Da; Liu, Li-Min; Lou, Xiong Wen David

    2016-10-20

    Lithium-sulfur batteries show advantages for next-generation electrical energy storage due to their high energy density and cost effectiveness. Enhancing the conductivity of the sulfur cathode and moderating the dissolution of lithium polysulfides are two key factors for the success of lithium-sulfur batteries. Here we report a sulfur host that overcomes both obstacles at once. With inherent metallic conductivity and strong adsorption capability for lithium-polysulfides, titanium monoxide@carbon hollow nanospheres can not only generate sufficient electrical contact to the insulating sulfur for high capacity, but also effectively confine lithium-polysulfides for prolonged cycle life. Additionally, the designed composite cathode further maximizes the lithium-polysulfide restriction capability by using the polar shells to prevent their outward diffusion, which avoids the need for chemically bonding all lithium-polysulfides on the surfaces of polar particles.

  20. LOW TEMPERATURE CATHODE SUPPORTED ELECTROLYTES

    Energy Technology Data Exchange (ETDEWEB)

    Harlan U. Anderson; Fatih Dogan; Vladimir Petrovsky

    2002-03-31

    This project has three main goals: Thin Films Studies, Preparation of Graded Porous Substrates and Basic Electrical Characterization and testing of Planar Single Cells. This period has continued to address the problem of making dense 1/2 to 5 {micro}m thick dense layers on porous substrates (the cathode LSM). Our current status is that we are making structures of 2-5 cm{sup 2} in area, which consist of either dense YSZ or CGO infiltrated into a 2-5 {micro}m thick 50% porous layer made of either nanoncrystalline CGO or YSZ powder. This composite structure coats a macroporous cathode or anode; which serves as the structural element of the bi-layer structure. These structures are being tested as SOFC elements. A number of structures have been evaluated both as symmetrical and as button cell configuration. Results of this testing indicates that the cathodes contribute the most to cell losses for temperatures below 750 C. In this investigation different cathode materials were studied using impedance spectroscopy of symmetric cells and IV characteristics of anode supported fuel cells. Cathode materials studied included La{sub 0.8}Sr{sub 0.2}Co{sub 0.2}Fe{sub 0.8}O{sub 3} (LSCF), La{sub 0.7}Sr{sub 0.2}MnO{sub 3} (LSM), Pr{sub 0.8}Sr{sub 0.2}Fe{sub 0.8}O{sub 3} (PSCF), Sm{sub 0.8}Sr{sub 0.2}Co{sub 0.2}Fe{sub 0.8}O{sub 3} (SSCF), and Yb{sub .8}Sr{sub 0.2}Co{sub 0.2}Fe{sub 0.8}O{sub 3} (SSCF). A new technique for filtering the Fourier transform of impedance data was used to increase the sensitivity of impedance analysis. By creating a filter specifically for impedance spectroscopy the resolution was increased. The filter was tailored to look for specific circuit elements like R//C, Warburg, or constant phase elements. As many as four peaks can be resolved using the filtering technique on symmetric cells. It may be possible to relate the different peaks to material parameters, like the oxygen exchange coefficient. The cathode grouped in order from lowest to highest ASR is

  1. Hollow Mill for Extraction of Stripped Titanium Screws: An Easy ...

    African Journals Online (AJOL)

    countries. The known alternative in such condition is ... Key words: Hollow mill, stripped screws, titanium locked plates ... used a locally manufactured stainless steel hollow mill, ... head ‑ plate hole” assembly as a mono‑block single unit. In.

  2. Method for the production of fabricated hollow microspheroids

    Science.gov (United States)

    Wickramanayake, Shan; Luebke, David R.

    2015-06-09

    The method relates to the fabrication of a polymer microspheres comprised of an asymmetric layer surrounding a hollow interior. The fabricated hollow microsphere is generated from a nascent hollow microsphere comprised of an inner core of core fluid surrounded by a dope layer of polymer dope, where the thickness of the dope layer is at least 10% and less than 50% of the diameter of the inner core. The nascent hollow microsphere is exposed to a gaseous environment, generating a vitrified hollow microsphere, which is subsequently immersed in a coagulation bath. Solvent exchange produces a fabricated hollow microsphere comprised of a densified outer skin surrounding a macroporous inner layer, which surrounds a hollow interior. In an embodiment, the polymer is a polyimide or a polyamide-imide, and the non-solvent in the core fluid and the coagulation bath is water. The fabricated hollow microspheres are particularly suited as solvent supports for gas separation processes.

  3. Evaluation Of Electromagnetic Fields For Frequencies 900 MHz-1 800 MHz In Tirana

    Directory of Open Access Journals (Sweden)

    Kuqi Dhurata

    2015-07-01

    Full Text Available Abstract The massive use of mobile phone as a communication tool nowadays is accompanied the ever increasing interest of the public and researchers for the possibly impact on human health as a result of exposure to the electromagnetic fields that accompany these devices. Therefore knowing the level of exposure electromagnetic fields of this electronic equipment has been and will be in the future interest object to the public and the subject of study for the researchers. In this paper are presents the results of measurements of electromagnetic fields for the frequencies 900 MHz - 1800 MHz used in mobile telephone in Tirana. These frequencies are included in the area radio frequency RF and Microwave MW 300 Hz - 300 GHz in the spectrum of electromagnetic waves and belong to non-ionizing radiation. The measurements were performed in different areas of Tirana. The purpose is to assess the level of exposure electromagnetic fields especially near areas where mobile antennas are mounted construction of dynamic digital mapping and comparison with the permitted levels of the exposure defined by the International Commission of Non Ionizing Radiation Protection ICNIRP. Through this publication the aim of the authors is to provide real information and reliable for the population.

  4. Technology development of solid state rf systems at 350 MHz and 325 MHz for RF accelerator

    International Nuclear Information System (INIS)

    Rama Rao, B.V.; Mishra, J.K.; Pande, Manjiri; Gupta, S.K.

    2011-01-01

    For decades vacuum tubes and klystrons have been used in high power application such as RF accelerators and broadcast transmitters. However, now, the solid-state technology can give power output in kilowatt regime. Higher RF power output can be achieved by combining several solid-state power amplifier modules using power combiners. This technology presents several advantages over traditional RF amplifiers, such as simpler start-up procedure, high modularity, high redundancy and flexibility, elimination of high voltage supplies and high power circulators, low operational cost, online maintenance without shut down of RF power station and no warm up time. In BARC, solid state amplifier technology development is being done both at 350 MHz and 325 MHz using RF transistors such as 1 kW LDMOS and 350 Watt VDMOS. Topology of input and output matching network in RF modules developed, consist of two L type matching sections with each section having a combination of series micro-strip line and parallel capacitor. The design is of equal Q for both the sections and of 25 ohm characteristics impedance of micro strip lines. Based on this, lengths of micro strips lines and values of shunt capacitors have been calculated. The calculated and simulated values of network elements have been compared. Similarly power combiners have been designed and developed based on Wilkinson techniques without internal resistors and using coaxial technology. This paper presents design and development of RF power amplifier modules, associated power combiner technologies and then integrated RF power amplifier. (author)

  5. Development of tree hollows in pedunculate oak (Quercus robur)

    OpenAIRE

    Ranius, Thomas; Niklasson, Mats; Berg, Niclas

    2009-01-01

    Many invertebrates, birds and mammals are dependent on hollow trees. For landscape planning that aims at persistence of species inhabiting hollow trees it is crucial to understand the development of such trees. In this study we constructed an individual-based simulation model to predict diameter distribution and formation of hollows in oak tree populations. Based on tree-ring data from individual trees, we estimated the ages when hollow formation commences for pedunculate oak (Quercus robur) ...

  6. Transmission properties of hollow-core photonic bandgap fibers

    DEFF Research Database (Denmark)

    Falk, Charlotte Ijeoma; Hald, Jan; Petersen, Jan C.

    2010-01-01

    Variations in optical transmission of four types of hollow-core photonic bandgap fibers are measured as a function of laser frequency. These variations influence the potential accuracy of gas sensors based on molecular spectroscopy in hollow-core fibers.......Variations in optical transmission of four types of hollow-core photonic bandgap fibers are measured as a function of laser frequency. These variations influence the potential accuracy of gas sensors based on molecular spectroscopy in hollow-core fibers....

  7. Adiabatic Rearrangement of Hollow PV Towers

    Directory of Open Access Journals (Sweden)

    Eric A Hendricks

    2010-10-01

    Full Text Available Diabatic heating from deep moist convection in the hurricane eyewall produces a towering annular structure of elevated potential vorticity (PV. This structure has been referred to as a hollow PV tower. The sign reversal of the radial gradient of PV satisfies the Charney-Stern necessary condition for combined barotropic-baroclinic instability. For thin enough annular structures, small perturbations grow exponentially, extract energy from the mean flow, and lead to hollow tower breakdown, with significant vortex structural and intensity change. The three-dimensional adiabatic rearrangements of two prototypical hurricane-like hollow PV towers (one thick and one thin are examined in an idealized framework. For both hollow towers, dynamic instability causes air parcels with high PV to be mixed into the eye preferentially at lower levels, where unstable PV wave growth rates are the largest. Little or no mixing is found to occur at upper levels. The mixing at lower and middle levels is most rapid for the breakdown of the thin hollow tower, consistent with previous barotropic results. For both hollow towers, this advective rearrangement of PV affects the tropical cyclone structure and intensity in a number of ways. First, the minimum central pressure and maximum azimuthal mean velocity simultaneously decrease, consistent with previous barotropic results. Secondly, isosurfaces of absolute angular momentum preferentially shift inward at low levels, implying an adiabatic mechanism by which hurricane eyewall tilt can form. Thirdly, a PV bridge, similar to that previously found in full-physics hurricane simulations, develops as a result of mixing at the isentropic levels where unstable PV waves grow most rapidly. Finally, the balanced mass field resulting from the PV rearrangement is warmer in the eye between 900 and 700 hPa. The location of this warming is consistent with observed warm anomalies in the eye, indicating that in certain instances the hurricane

  8. Microfabricated hollow microneedle array using ICP etcher

    Science.gov (United States)

    Ji, Jing; Tay, Francis E. H.; Miao, Jianmin

    2006-04-01

    This paper presents a developed process for fabrication of hollow silicon microneedle arrays. The inner hollow hole and the fluidic reservoir are fabricated in deep reactive ion etching. The profile of outside needles is achieved by the developed fabrication process, which combined isotropic etching and anisotropic etching with inductively coupled plasma (ICP) etcher. Using the combination of SF6/O2 isotropic etching chemistry and Bosch process, the high aspect ratio 3D and high density microneedle arrays are fabricated. The generated needle external geometry can be controlled by etching variables in the isotropic and anisotropic cases.

  9. Microfabricated hollow microneedle array using ICP etcher

    International Nuclear Information System (INIS)

    Ji Jing; Tay, Francis E H; Miao Jianmin

    2006-01-01

    This paper presents a developed process for fabrication of hollow silicon microneedle arrays. The inner hollow hole and the fluidic reservoir are fabricated in deep reactive ion etching. The profile of outside needles is achieved by the developed fabrication process, which combined isotropic etching and anisotropic etching with inductively coupled plasma (ICP) etcher. Using the combination of SF 6 /O 2 isotropic etching chemistry and Bosch process, the high aspect ratio 3D and high density microneedle arrays are fabricated. The generated needle external geometry can be controlled by etching variables in the isotropic and anisotropic cases

  10. Microfabricated hollow microneedle array using ICP etcher

    Energy Technology Data Exchange (ETDEWEB)

    Ji Jing [Mechanical Engineering National University of Singapore, 119260, Singapore (Singapore); Tay, Francis E H [Mechanical Engineering National University of Singapore, 119260, Singapore (Singapore); Miao Jianmin [MicroMachines Center, School of Mechanical and Aerospace Engineering, Nanyang Technological University, 50 Nanyang Avenue, 639798 (Singapore)

    2006-04-01

    This paper presents a developed process for fabrication of hollow silicon microneedle arrays. The inner hollow hole and the fluidic reservoir are fabricated in deep reactive ion etching. The profile of outside needles is achieved by the developed fabrication process, which combined isotropic etching and anisotropic etching with inductively coupled plasma (ICP) etcher. Using the combination of SF{sub 6}/O{sub 2} isotropic etching chemistry and Bosch process, the high aspect ratio 3D and high density microneedle arrays are fabricated. The generated needle external geometry can be controlled by etching variables in the isotropic and anisotropic cases.

  11. Computational predictions of zinc oxide hollow structures

    Science.gov (United States)

    Tuoc, Vu Ngoc; Huan, Tran Doan; Thao, Nguyen Thi

    2018-03-01

    Nanoporous materials are emerging as potential candidates for a wide range of technological applications in environment, electronic, and optoelectronics, to name just a few. Within this active research area, experimental works are predominant while theoretical/computational prediction and study of these materials face some intrinsic challenges, one of them is how to predict porous structures. We propose a computationally and technically feasible approach for predicting zinc oxide structures with hollows at the nano scale. The designed zinc oxide hollow structures are studied with computations using the density functional tight binding and conventional density functional theory methods, revealing a variety of promising mechanical and electronic properties, which can potentially find future realistic applications.

  12. Barium-Dispenser Thermionic Cathode

    Science.gov (United States)

    Wintucky, Edwin G.; Green, M.; Feinleib, M.

    1989-01-01

    Improved reservoir cathode serves as intense source of electrons required for high-frequency and often high-output-power, linear-beam tubes, for which long operating lifetime important consideration. High emission-current densities obtained through use of emitting surface of relatively-low effective work function and narrow work-function distribution, consisting of coat of W/Os deposited by sputtering. Lower operating temperatures and enhanced electron emission consequently possible.

  13. Modelling effects of current distributions on performance of micro-tubular hollow fibre solid oxide fuel cells

    International Nuclear Information System (INIS)

    Doraswami, U.; Droushiotis, N.; Kelsall, G.H.

    2010-01-01

    A three-dimensional model, considering mass, momentum, energy and charge conservation, was developed and the equations solved to describe the physico-chemical phenomena occurring within a single, micro-tubular hollow fibre solid oxide fuel cell (HF-SOFC). The model was used to investigate the spatial distributions of potential, current and reactants in a 10 mm long HF-SOFC. The predicted effects of location of current collectors, electrode conductivities, cathode thickness and porosity were analysed to minimise the ranges of current density distributions and maximise performance by judicious design. To decrease the computational load, azimuthal symmetry was assumed to model 50 and 100 mm long reactors in 2-D. With connectors at the same end of the HF-SOFC operating at a cell voltage of 0.5 V and a mean 5 kA m -2 , axial potential drops of ca. 0.14 V in the cathode were predicted, comparable to the cathode activation overpotential. Those potential drops caused average current densities to decrease from ca. 6.5 to ca.1 kA m -2 as HF-SOFC length increased from 10 to 100 mm, at which much of the length was inactive. Peak power densities were predicted to vary from 3.8 to -2 , depending on the location of the current collectors; performance increased with increasing cathode thickness and decreasing porosity.

  14. Ion energy distributions in bipolar pulsed-dc discharges of methane measured at the biased cathode

    Energy Technology Data Exchange (ETDEWEB)

    Corbella, C; Rubio-Roy, M; Bertran, E; Portal, S; Pascual, E; Polo, M C; Andujar, J L, E-mail: corbella@ub.edu [FEMAN Group, IN2UB, Departament de Fisica Aplicada i Optica, Universitat de Barcelona, c/ MartI i Franques 1, 08028 Barcelona (Spain)

    2011-02-15

    The ion fluxes and ion energy distributions (IED) corresponding to discharges in methane (CH{sub 4}) were measured in time-averaged mode with a compact retarding field energy analyser (RFEA). The RFEA was placed on a biased electrode at room temperature, which was powered by either radiofrequency (13.56 MHz) or asymmetric bipolar pulsed-dc (250 kHz) signals. The shape of the resulting IED showed the relevant populations of ions bombarding the cathode at discharge parameters typical in the material processing technology: working pressures ranging from 1 to 10 Pa and cathode bias voltages between 100 and 200 V. High-energy peaks in the IED were detected at low pressures, whereas low-energy populations became progressively dominant at higher pressures. This effect is attributed to the transition from collisionless to collisional regimes of the cathode sheath as the pressure increases. On the other hand, pulsed-dc plasmas showed broader IED than RF discharges. This fact is connected to the different working frequencies and the intense peak voltages (up to 450 V) driven by the pulsed power supply. This work improves our understanding in plasma processes at the cathode level, which are of crucial importance for the growth and processing of materials requiring controlled ion bombardment. Examples of industrial applications with these requirements are plasma cleaning, ion etching processes during fabrication of microelectronic devices and plasma-enhanced chemical vapour deposition of hard coatings (diamond-like carbon, carbides and nitrides).

  15. Cell death induced by GSM 900-MHz and DCS 1800-MHz mobile telephony radiation

    International Nuclear Information System (INIS)

    Panagopoulos, D. J; Chavdoula, E. D.; Nezis, I. P.; Margaritis, L. H.

    2007-01-01

    In the present study, the TUNEL (Terminal deoxynucleotide transferase dUTP Nick End Labeling) assay '' a well known technique widely used for detecting fragmented DNA in various types of cells'' was used to detect cell death (DNA fragmentation) in a biological model, the early and mid stages of oogenesis of the insect Drosophila melanogaster. The flies were exposed in vivo to either GSM 900-MHz (Global System for Mobile telecommunications) or DCS 1800-MHz (Digital Cellular System) radiation from a common digital mobile phone, for few minutes per day during the first 6 days of their adult life. The exposure conditions were similar to those to which a mobile phone user is exposed, and were determined according to previous studies of ours [D.J. Panagopoulos, A. Karabarbounis, L.H. Margaritis, Effect of GSM 900-MHz mobile phone radiation on the reproductive capacity of D. melanogaster, Electromagn. Biol. Med. 23 (1) (2004) 29''43; D.J. Panagopoulos, N. Messini, A. Karabarbounis, A.L. Philippetis, L.H. Margaritis, Radio frequency electromagnetic radiation within ''safety levels'' alters the physiological function of insects, in: P. Kostarakis, P. Stavroulakis (Eds.), Proceedings of the Millennium International Workshop on Biological Effects of Electromagnetic Fields, Heraklion, Crete, Greece, October 17''20, 2000, pp. 169''175, ISBN: 960-86733-0-5; D.J. Panagopoulos, L.H. Margaritis, Effects of electromagnetic fields on the reproductive capacity of D. melanogaster, in: P. Stavroulakis (Ed.), Biological Effects of Electromagnetic Fields, Springer, 2003, pp. 545''578], which had shown a large decrease in the oviposition of the same insect caused by GSM radiation. Our present results suggest that the decrease in oviposition previously reported, is due to degeneration of large numbers of egg chambers after DNA fragmentation of their constituent cells, induced by both types of mobile telephony radiation. Induced cell death is recorded for the first time, in all types of

  16. CAMEX-4 MIPS 915 MHZ DOPPLER WIND PROFILER V1

    Data.gov (United States)

    National Aeronautics and Space Administration — The CAMEX-4 MIPS 915 MHZ Doppler Wind Profiler dataset was collected by the University of Alabama in Huntsville (UAH) Mobile Integrated Profiling System (MIPS),...

  17. CAMEX-4 MIPS 915 MHZ DOPPLER WIND PROFILER V1

    Data.gov (United States)

    National Aeronautics and Space Administration — The University of Alabama in Huntsville (UAH) Mobile Integrated Profiling System (MIPS) is a mobile atmospheric profiling system. It includes a 915 MHz Doppler...

  18. Analog Fiber Optic Link with DC-100 MHz Bandwidth

    National Research Council Canada - National Science Library

    Sullivan, C. A; Girardi, P. G; Lohrmann, Dieter R

    2008-01-01

    An analog fiber optic link covering the frequency range from DC to 100 MHz was designed, constructed, and tested, in order to connect a 10 kA pulse current probe to oscilloscopes for oscillographing...

  19. Hollow-in-Hollow Carbon Spheres for Lithium-ion Batteries with Superior Capacity and Cyclic Performance

    International Nuclear Information System (INIS)

    Zang, Jun; Ye, Jianchuan; Fang, Xiaoliang; Zhang, Xiangwu; Zheng, Mingsen; Dong, Quanfeng

    2015-01-01

    Highlights: • Hollow-in-hollow structured HIHCS was synthesized via a facile templating strategy. • The HCS core and hollow carbon shell constitute the hollow-in-hollow structure. • The HIHCS exhibited superior rate capability and cycle stability as anode material. • The excellent performance is attributed to the unique hollow-in-hollow structure. - Abstract: Hollow spheres structured materials have been intensively pursued due to their unique properties for energy storage. In this paper, hollow-in-hollow carbon spheres (HIHCS) with a multi-shelled structure were successfully synthesized using a facile hard-templating procedure. When evaluated as anode material for lithium-ion batteries, the resultant HIHCS anode exhibited superior capacity and cycling stability than HCS. It could deliver reversible capacities of 937, 481, 401, 304 and 236 mAh g −1 at current densities of 0.1 A g −1 , 1 A g −1 , 2 A g −1 , 5 A g −1 and 10 A g −1 , respectively. And capacity fading is not apparent in 500 cycles at 5 A g −1 . The excellent performance of the HIHCS anode is ascribed to its unique hollow-in-hollow structure and high specific surface area.

  20. 500 MHz transient digitizers based on GaAs CCDs

    Energy Technology Data Exchange (ETDEWEB)

    Bryman, D A; Constable, M; Cresswell, J V; Daviel, A; LeNoble, M; Mildenberger, J; Poutissou, R

    1996-11-01

    A system of 500 MHz transient digitizers based on gallium arsenide resistive gate charged coupled devices has been developed for an experiment studying rare K decays. CCDs with dynamic range of 8-bits and 128 or 320 pixels are used as analog pipelines. The CCD`s are driven by a single phase transport system. Data readout and manipulation occurs at 15.6 MHz. (authors). 12 refs., 15 figs.

  1. Origin of microplasma instabilities during DC operation of silicon based microhollow cathode devices

    Science.gov (United States)

    Felix, Valentin; Lefaucheux, Philippe; Aubry, Olivier; Golda, Judith; Schulz-von der Gathen, Volker; Overzet, Lawrence J.; Dussart, Rémi

    2016-04-01

    The failure mechanisms of micro hollow cathode discharges (MHCD) in silicon have been investigated using their I-V characteristics, high speed photography and scanning electron microscopy. Experiments were carried out in helium. We observed I-V instabilities in the form of rapid voltage decreases associated with current spikes. The current spikes can reach values more than 100 times greater than the average MHCD current. (The peaks can be more than 1 Ampere for a few 10’s of nanoseconds.) These current spikes are correlated in time with 3-10 μm diameter optical flashes that occur inside the cavities. The SEM characterizations indicated that blister-like structures form on the Si surface during plasma operation. Thin Si layers detach from the surface in localized regions. We theorize that shallow helium implantation occurs and forms the ‘blisters’ whenever the Si is biased as the cathode. These blisters ‘explode’ when the helium pressure inside them becomes too large leading to the transient micro-arcs seen in both the optical emission and the I-V characteristics. We noted that blisters were never found on the metal counter electrode, even when it was biased as the cathode (and the Si as the anode). This observation led to a few suggestions for delaying the failure of Si MHCDs. One may coat the Si cathode (cavities) with blister resistant material; design the MHCD array to operate with the Si as the anode rather than as the cathode; or use a gas additive to prevent surface damage. Regarding the latter, tests using SF6 as the gas additive successfully prevented blister formation through rapid etching. The result was an enhanced MHCD lifetime.

  2. Origin of microplasma instabilities during DC operation of silicon based microhollow cathode devices

    International Nuclear Information System (INIS)

    Felix, Valentin; Lefaucheux, Philippe; Aubry, Olivier; Dussart, Rémi; Golda, Judith; Schulz-von der Gathen, Volker; Overzet, Lawrence J

    2016-01-01

    The failure mechanisms of micro hollow cathode discharges (MHCD) in silicon have been investigated using their I-V characteristics, high speed photography and scanning electron microscopy. Experiments were carried out in helium. We observed I–V instabilities in the form of rapid voltage decreases associated with current spikes. The current spikes can reach values more than 100 times greater than the average MHCD current. (The peaks can be more than 1 Ampere for a few 10’s of nanoseconds.) These current spikes are correlated in time with 3–10 μm diameter optical flashes that occur inside the cavities. The SEM characterizations indicated that blister-like structures form on the Si surface during plasma operation. Thin Si layers detach from the surface in localized regions. We theorize that shallow helium implantation occurs and forms the ‘blisters’ whenever the Si is biased as the cathode. These blisters ‘explode’ when the helium pressure inside them becomes too large leading to the transient micro-arcs seen in both the optical emission and the I–V characteristics. We noted that blisters were never found on the metal counter electrode, even when it was biased as the cathode (and the Si as the anode). This observation led to a few suggestions for delaying the failure of Si MHCDs. One may coat the Si cathode (cavities) with blister resistant material; design the MHCD array to operate with the Si as the anode rather than as the cathode; or use a gas additive to prevent surface damage. Regarding the latter, tests using SF 6 as the gas additive successfully prevented blister formation through rapid etching. The result was an enhanced MHCD lifetime. (paper)

  3. Reflective article having a sacrificial cathodic layer

    Science.gov (United States)

    Kabagambe, Benjamin; Buchanan, Michael J.; Scott, Matthew S.; Rearick, Brian K.; Medwick, Paul A.; McCamy, James W.

    2017-09-12

    The present invention relates to reflective articles, such as solar mirrors, that include a sacrificial cathodic layer. The reflective article, more particularly includes a substrate, such as glass, having a multi-layered coating thereon that includes a lead-free sacrificial cathodic layer. The sacrificial cathodic layer includes at least one transition metal, such as a particulate transition metal, which can be in the form of flakes (e.g., zinc flakes). The sacrificial cathodic layer can include an inorganic matrix formed from one or more organo-titanates. Alternatively, the sacrificial cathodic layer can include an organic polymer matrix (e.g., a crosslinked organic polymer matrix formed from an organic polymer and an aminoplast crosslinking agent). The reflective article also includes an outer organic polymer coating, that can be electrodeposited over the sacrificial cathodic layer.

  4. Molecular motor transport through hollow nanowires

    DEFF Research Database (Denmark)

    Lard, Mercy; Ten Siethoff, Lasse; Generosi, Johanna

    2014-01-01

    -driven motion of fluorescent probes (actin filaments) through 80 nm wide, Al2O 3 hollow nanowires of micrometer length. The motor-driven transport is orders of magnitude faster than would be possible by passive diffusion. The system represents a necessary element for advanced devices based on gliding assays...

  5. Hollow micro string based calorimeter device

    DEFF Research Database (Denmark)

    2014-01-01

    positions so as to form a free released double clamped string in-between said two longitudinally distanced positions said micro-channel string comprising a microfluidic channel having a closed cross section and extending in the longitudinal direction of the hollow string, acoustical means adapted...

  6. Hollow fibre supported liquid membrane extraction of ...

    African Journals Online (AJOL)

    A simple sample pre-treatment method utilizing hollow fibre supported liquid membrane (HFSLM) was carried out on pharmaceuticals samples comprising of cough syrups (CS1 and CS2) and an anti-inflammatory product (AI). The active ingredients targeted in the extraction process were diphenylhydramine (DPH), ...

  7. TEACHING PHYSICS: Biking around a hollow sphere

    Science.gov (United States)

    Mak, Se-yuen; Yip, Din-yan

    1999-11-01

    The conditions required for a cyclist riding a motorbike in a horizontal circle on or above the equator of a hollow sphere are derived using concepts of equilibrium and the condition for uniform circular motion. The result is compared with an empirical analysis based on a video show. Some special cases of interest derived from the general solution are elaborated.

  8. Preventing Corrosion by Controlling Cathodic Reaction Kinetics

    Science.gov (United States)

    2016-03-25

    3. DATES COVERED (From - To) 09/23/15 - 04/22/16 4. TITLE AND SUBTITLE Sa. CONTRACT NUMBER Preventing Corrosion by Controlling Cathodic Reaction...Preventing corrosion by controlling cathodic reaction kinetics Progress Report for Period: 1 SEP 2015-31 MAR 2016 John Keith Department of...25 March 2016 Preventing corrosion by controlling cathodic reaction kinetics Annual Summary Report: FY16 PI: John Keith, 412-624-7016,jakeith

  9. The 136 MHz/400 MHz earth station antenna-noise temperature prediction program documentation for RAE-B

    Science.gov (United States)

    Chin, M.

    1972-01-01

    A simulation study to determine the 136 MHz and 400 MHz noise temperature of the ground network antennas which will track the RAE-B satellite during data transmission periods is described. Since the noise temperature of the antenna effectively sets the signal-to-noise ratio (SNR) of the received signal, a knowledge of SNR will be helpful in locating the optimum time windows for data transmission during low-noise periods. Antenna-noise temperatures at 136 MHz and 400 MHz will be predicted for selected earth-based ground stations which will support RAE-B. The antenna-noise temperature predictions will include the effects of galactic-brightness temperature, the sun, and the brightest radio stars. Predictions will cover the ten-month period from March 1, 1973 to December 31, 1973. The RAE-B mission will be expecially susceptible to SNR degradation during the two eclipses of the Sun occurring in this period.

  10. The 136 MHZ/400 MHz earth station antenna-noise temperature prediction program for RAE-B

    Science.gov (United States)

    Taylor, R. E.; Fee, J. J.; Chin, M.

    1972-01-01

    A simulation study was undertaken to determine the 136 MHz and 400 MHz noise temperature of the ground network antennas which will track the RAE-B satellite during data transmission periods. Since the noise temperature of the antenna effectively sets the signal-to-noise ratio of the received signal, a knowledge of SNR will be helpful in locating the optimum time windows for data transmission during low noise periods. Antenna noise temperatures will be predicted for selected earth-based ground stations which will support RAE-B. Telemetry data acquisition will be at 400 MHz; tracking support at 136 MHz will be provided by the Goddard Range and Range Rate (RARR) stations. The antenna-noise temperature predictions will include the effects of galactic-brightness temperature, the sun, and the brightest radio stars. Predictions will cover the ten-month period from March 1, 1973 to December 31, 1973.

  11. Evidence of fire resistance of hollow-core slabs

    DEFF Research Database (Denmark)

    Hertz, Kristian Dahl; Sørensen, Lars Schiøtt; Giuliani, Luisa

    is therefore going on in the Netherlands about the fire resistance of hollow-core slabs. In 2014 the producers of hollow-core slabs have published a report of a project called Holcofire containing a collection of 162 fire tests on hollow-core slabs giving for the first time an overview of the fire tests made....... The present paper analyses the evidence now available for assessment of the fire resistance of extruded hollow-core slabs. The 162 fire tests from the Holcofire report are compared against the requirements for testing from the product standard for hollow-core slabs EN1168 and knowledge about the possible......Hollow-core slabs have during the past 50 years comprised a variety of different structures with different cross-sections and reinforcement. At present the extruded hollow-core slabs without cross-reinforcement in the bottom flange and usually round or oval longitudinal channels (holes...

  12. Cold cathode arc model in mercury discharges

    International Nuclear Information System (INIS)

    Li, Y.M.; Byszewski, W.W.; Budinger, A.B.

    1990-01-01

    Voltage/current characteristics measured during the starting of metal halide lamps indicate a low voltage discharge when condensates (mainly mercury) are localized on the electrodes. In this case, even with a cold cathode which does not emit electrons, the current is very high and voltage across the lamp drops to about 15 to 20 V. This type of discharge is similar to the cold cathode mercury vapor arc found in mercury pool rectifiers. The cathode sheath in the mercury vapor arc is characterized by very small cathode spot size, on the order of 10 -c cm 2 , very high current density of about 10 6 A/cm 2 and very low cathode fall of approximately 10 volts. The discharge is modified and generalized to describe the cathode phenomena in the cold cathode mercury vapor arc. The sensitivity of calculated discharge parameters with respect to such modifications were examined. Results show that the cathode fall voltage remains fairly constant (7-8 volts) with large fractional variations of metastable mercury atoms bombarding the cathode. This result compares very well with experimental waveforms when anode fall and plasma voltage approximations are incorporated

  13. Two-beam virtual cathode accelerator

    International Nuclear Information System (INIS)

    Peter, W.

    1992-01-01

    A proposed method to control the motion of a virtual cathode is investigated. Applications to collective ion acceleration and microwave generation are indicated. If two counterstreaming relativistic electron beams of current I are injected into a drift tube of space-charge-limiting current I L = 2I, it is shown that one beam can induce a moving virtual cathode in the other beam. By dynamically varying the current injected into the drift tube region, the virtual cathode can undergo controlled motion. For short drift tubes, the virtual cathodes on each end are strongly-coupled and undergo coherent large-amplitude spatial oscillations within the drift tube

  14. Evolution of nickel sulfide hollow spheres through topotactic transformation

    Science.gov (United States)

    Wei, Chengzhen; Lu, Qingyi; Sun, Jing; Gao, Feng

    2013-11-01

    In this study, a topotactic transformation route was proposed to synthesize single-crystalline β-NiS hollow spheres with uniform phase and morphology evolving from polycrystalline α-NiS hollow spheres. Uniform polycrystalline α-NiS hollow spheres were firstly prepared with thiourea and glutathione as sulfur sources under hydrothermal conditions through the Kirkendall effect. By increasing the reaction temperature the polycrystalline α-NiS hollow spheres were transformed to uniform β-NiS hollow spheres. The β-NiS crystals obtained through the topotactic transformation route not only have unchanged morphology of hollow spheres but are also single-crystalline in nature. The as-prepared NiS hollow spheres display a good ability to remove the organic pollutant Congo red from water, which makes them have application potential in water treatment.In this study, a topotactic transformation route was proposed to synthesize single-crystalline β-NiS hollow spheres with uniform phase and morphology evolving from polycrystalline α-NiS hollow spheres. Uniform polycrystalline α-NiS hollow spheres were firstly prepared with thiourea and glutathione as sulfur sources under hydrothermal conditions through the Kirkendall effect. By increasing the reaction temperature the polycrystalline α-NiS hollow spheres were transformed to uniform β-NiS hollow spheres. The β-NiS crystals obtained through the topotactic transformation route not only have unchanged morphology of hollow spheres but are also single-crystalline in nature. The as-prepared NiS hollow spheres display a good ability to remove the organic pollutant Congo red from water, which makes them have application potential in water treatment. Electronic supplementary information (ESI) available: XRD patterns; SEM images and TEM images. See DOI: 10.1039/c3nr03371f

  15. Cathode materials: A personal perspective

    Energy Technology Data Exchange (ETDEWEB)

    Goodenough, John B. [Texas Materials Institute, University of Texas at Austin, ETC 9.102, 1 University Station, Austin, TX 78712-1063 (United States)

    2007-12-06

    A thermodynamically stable rechargeable battery has a voltage limited by the window of the electrolyte. An aqueous electrolyte has a window of 1.2 eV, which prevents achieving the high energy density desired for many applications. A non-aqueous electrolyte with a window of 5 eV requires Li{sup +} rather than H{sup +} as the working ion. Early experiments with Li{sub x}TiS{sub 2} cathodes showed competitive capacity and rate capability, but problems with a lithium anode made the voltage of a safe cell based on a sulfide cathode too low to be competitive with a nickel/metal-hydride battery. Transition-metal oxides can give voltages of 4.5 V versus Li{sup +}/Li{sup 0}. However, the challenge with oxides has been to obtain a competitive capacity and rate capability while retaining a high voltage with low-cost, environmentally friendly cathode materials. Comparisons will be made between layered Li{sub 1-x}MO{sub 2}, spinels Li{sub 1-x}[M{sub 2}]O{sub 4}, and olivines Li{sub 1-x}MPO{sub 4} having 0 < x < 1. Although higher capacities can be obtained with layered Li{sub 1-x}MO{sub 2} compounds, which have enabled the wireless revolution, their metastability makes them unlikely to be used in power applications. The spinel and olivine framework structures have been shown to be capable of charge/discharge rates of over 10C with a suitable temperature range for plug-in hybrid vehicles. (author)

  16. Fundamental aspects of cathodic sputtering

    International Nuclear Information System (INIS)

    Harman, R.

    1979-01-01

    The main fundamental aspects and problems of cathodic sputtering used mainly for thin film deposition and sputter etching are discussed. Among many types of known sputtering techniques the radiofrequency /RF/ diode sputtering is the most universal one and is used for deposition of metals, alloys, metallic compounds, semiconductors and insulators. It seems that nowadays the largest number of working sputtering systems is of diode type. Sometimes also the dc or rf triode sputtering systems are used. The problems in these processes are practically equivalent and comparable with the problems in the diode method and therefore our discussion will be, in most cases applicable for both, the diode and triode methods

  17. Cathode-follower power amplifier

    International Nuclear Information System (INIS)

    Giordano, S.; Puglisi, M.

    1983-01-01

    In circular accelerators and particularly in storage rings it is essential that the total impedance, as seen by the beam, be kept below some critical value. A model of the accelerating system was built using a single-ended cathode-follower amplifier driving a ferrite-loaded cavity. The system operated at 234.5 kHz with a peak output voltage of +-10 kV on the gap. The dynamic output impedance, as measured on the gap, was < 15 ohms

  18. Production of a large area diffuse arc plasma with multiple cathode

    International Nuclear Information System (INIS)

    Wang Cheng; Cui Hai-Chao; Li Wan-Wan; Liao Meng-Ran; Xia Wei-Dong; Xia Wei-Luo

    2017-01-01

    An arc channel at atmospheric pressure tends to shrink generally. In this paper, a non-transferred DC arc plasma device with multiple cathode is introduced to produce a large area arc plasma at atmospheric pressure. This device is comprised of a 42-mm diameter tubular chamber, multiple cathode which is radially inserted into the chamber, and a tungsten anode with a nozzle in its center. In argon/helium atmosphere, a large area and circumferential homogenous diffuse arc plasma, which fills the entire cross section surrounded by the cathode tips, is observed. Results show that the uniformity and stability of diffuse arc plasma are strongly related to the plasma forming gas. Based on these experimental results, an explanation to the arc diffusion is suggested. Moreover, the electron excitation temperature and electron density measured in diffuse helium plasma are much lower than those of constricted arc column, which indicates the diffuse helium plasma probably deviates from the local thermodynamic equilibrium state. Unlike the common non-transferred arc plasma devices, this device can provide a condition for axial-fed feedstock particles. The plasma device is attempted to spheroidize alumina powders by using the central axis to send the powder. Results show that the powder produced is usually a typical hollow sphere. (paper)

  19. Preliminary Mechanical Design Study of the Hollow Electron Lens for HL-LHC

    Science.gov (United States)

    Zanoni, Carlo; Gobbi, Giorgia; Perini, Diego; Stancari, Giulio

    2017-07-01

    A Hollow Electron Lens (HEL) has been proposed in order to improve performance of halo control and collimation in the Large Hadron Collider in view of its High Luminosity upgrade (HL-LHC). The concept is based on a hollow beam of electrons that travels around the protons for a few meters. The electron beam is produced by a cathode and then guided by a strong magnetic field. The first step of the design is the definition of the magnetic field that drives the electron trajectories. The estimation of such trajectories by means of a dedicated MATLAB tool is presented. The influence of the main geometrical and electrical parameters is analyzed and discussed. Then, the main mechanical design choices for the solenoids, cryostats gun and collector are described. The aim of this paper is to provide an overview of the feasibility study of the Electron Lens for LHC. The methods used in this study also serve as examples for future mechanical and integration designs of similar devices.

  20. Preliminary Mechanical Design Study of the Hollow Electron Lens for HL-LHC

    Energy Technology Data Exchange (ETDEWEB)

    Zanoni, Carlo [CERN; Gobbi, Giorgia [CERN; Perini, Diego [CERN; Stancari, Giulio [Fermilab

    2017-05-01

    A Hollow Electron Lens (HEL) has been proposed in order to improve performance of halo control and collimation in the Large Hadron Collider in view of its High Luminosity upgrade (HL-LHC). The concept is based on a hollow beam of electrons that travels around the protons for a few meters. The electron beam is produced by a cathode and then guided by a strong magnetic field. The first step of the design is the definition of the magnetic field that drives the electron trajectories. The estimation of such trajectories by means of a dedicated MATLAB tool is presented. The influence of the main geometrical and electrical parameters is analyzed and discussed. Then, the main mechanical design choices for the solenoids, cryostats gun and collector are described. The aim of this paper is to provide an overview of the feasibility study of the Electron Lens for LHC. The methods used in this study also serve as examples for future mechanical and integration designs of similar devices.

  1. Two-dimensional simulations of multi-hollow VHF SiH4/H2 plasma

    Directory of Open Access Journals (Sweden)

    Li-Wen Su

    2018-02-01

    Full Text Available A triode multi-hollow VHF SiH4/H2 plasma (60 MHz was examined at a pressure of 20 Pa by two-dimensional simulations using the fluid model. In this study, we considered the effect of the rate constant of reaction, SiH3 + SiH3→SiH2 + SiH4, on the plasma characteristics. A typical VHF plasma of a high-electron density with a low-electron temperature was obtained between two discharge electrodes. Spatial profiles of SiH3+, SiH2+, SiH3- and SiH3 densities were similar to that of the electron density while the electron temperature had a maximum value near the two discharge electrodes. It was found that the SiH3 radical density did not decrease rapidly near the substrate and the electron temperature was lower than 1 eV, suggesting that the triode multi-hollow plasma source can provide high quality amorphous silicon with a high deposition rate.

  2. Acousto-optic mode coupling excited by flexural waves in simplified hollow-core photonic crystal fibers

    International Nuclear Information System (INIS)

    Zhang, Hao; Qiu, Minghui; Wu, Zhifang; Dong, Hongguang; Liu, Bo; Miao, Yinping

    2013-01-01

    We have demonstrated the formation of an acoustic grating in a simplified hollow-core photonic crystal fiber, which consists of a hollow hexagonal core and six crown-like air holes, by applying flexural acoustic waves along the fiber axis. The dependence of the resonance wavelength on the applied acoustic frequency has been acquired on the basis of the theoretical calculation of the phase matching curve; it is in good agreement with our experimental observation of the transmission spectral evolution as the applied acoustic frequency varies. Experimental results show that the acoustic grating resonance peak possesses acoustic frequency and strain dependences of 728 nm MHz −1 and −6.98 pm με −1 , respectively, based on which high-performance acousto-optic tunable filters and fiber-optic strain sensors with high sensitivity could be achieved. And furthermore, the research work presented in this paper indicates that microbending rather than physical deformation is the main physical mechanism that leads to the formation of equivalent long-period gratings, which would be of significance for developing related grating devices based on simplified hollow-core photonic crystal fibers. (paper)

  3. Cathodic hydrogen charging of zinc

    International Nuclear Information System (INIS)

    Panagopoulos, C.N.; Georgiou, E.P.; Chaliampalias, D.

    2014-01-01

    Highlights: •Incorporation of hydrogen into zinc and formation of zinc hydrides. •Investigation of surface residual stresses due to hydrogen diffusion. •Effect of hydrogen diffusion and hydride formation on mechanical properties of Zn. •Hydrogen embrittlement phenomena in zinc. -- Abstract: The effect of cathodic hydrogen charging on the structural and mechanical characteristics of zinc was investigated. Hardening of the surface layers of zinc, due to hydrogen incorporation and possible formation of ZnH 2 , was observed. In addition, the residual stresses brought about by the incorporation of hydrogen atoms into the metallic matrix, were calculated by analyzing the obtained X-ray diffraction patterns. Tensile testing of the as-received and hydrogen charged specimens revealed that the ductility of zinc decreased significantly with increasing hydrogen charging time, for a constant value of charging current density, and with increasing charging current density, for a constant value of charging time. However, the ultimate tensile strength of this material was slightly affected by the hydrogen charging procedure. The cathodically charged zinc exhibited brittle transgranular fracture at the surface layers and ductile intergranular fracture at the deeper layers of the material

  4. Ion source with plasma cathode

    International Nuclear Information System (INIS)

    Yabe, E.

    1987-01-01

    A long lifetime ion source with plasma cathode has been developed for use in ion implantation. In this ion source, a plasma of a nonreactive working gas serves as a cathode in place of a thermionic tungsten filament used in the Freeman ion source. In an applied magnetic field, the plasma is convergent, i.e., filamentlike; in zero magnetic field, it turns divergent and spraylike. In the latter case, the plasma exhibits a remarkable ability when the working gas has an ionization potential larger than the feed gas. By any combination of a working gas of either argon or neon and a feed gas of AsF 5 or PF 5 , the lifetime of this ion source was found to be more than 90 h with an extraction voltage of 40 kV and the corresponding ion current density 20 mA/cm 2 . Mass spectrometry results show that this ion source has an ability of generating a considerable amount of As + and P + ions from AsF 5 and PF 5 , and hence will be useful for realizing a fully cryopumped ion implanter system. This ion source is also eminently suitable for use in oxygen ion production

  5. Development of disposable membrane hydrophones for a frequency range from 1MHz to 10MHz.

    Science.gov (United States)

    Lee, Jae-Wan; Ohm, Won-Suk; Kim, Yong-Tae

    2017-11-01

    A method for fabricating disposable membrane hydrophones is presented. The disposable hydrophones are intended for onetime use in such damaging environments as chemically contaminating fluids and high-amplitude (peak amplitude ∼100MPa) shock wave fields, where the use of commercial membrane hydrophones is not recommended. Fabrication of a hydrophone is done using only off-the-shelf components and hand tools, which translates into ease of fabrication and orders-of-magnitude reduction in unit cost. In particular, poling and sputtering, the two processes that are chiefly responsible for the cost and difficulty associated with the conventional fabrication method, are replaced with the use of pre-poled polyvinylidene fluoride (PVDF) films and polyethylene terephthalate (PET)-coated aluminum foils, respectively. Despite the seemingly crude construction, these disposable hydrophones can exhibit voltage sensitivity response that compares favorably with that of commercial hydrophones. For example, one prototype having a 2mm×2mm active element shows the end-of-cable voltage sensitivity of -270 (±1.9) dB re 1V/μPa over the frequency range of 1-10MHz. Copyright © 2017 Elsevier B.V. All rights reserved.

  6. Pipelines cathodic protection design methodologies for impressed ...

    African Journals Online (AJOL)

    Several inadequate designs of cathodically polarized offshore and onshore pipelines have been reported in Nigeria owing to design complexity and application of the cathodic protection system. The present study focused on critical and detailed approach in impressed current and sacrificial anode design calculation ...

  7. Model of dopant action in oxide cathodes

    International Nuclear Information System (INIS)

    Engelsen, Daniel den; Gaertner, Georg

    2005-01-01

    The paper describes an electrochemical model, which largely explains the formation of Ba in the oxide cathode at activation and normal operation. In a non-doped oxide cathode electrolysis of BaO is, besides the exchange reaction from the activators in the cathode nickel, an important source of Ba. By doping with rare earth oxides the conductivity of the oxide layer increases, which implies that the potential difference during current drawing over the oxide layer becomes lower and electrolysis of BaO is suppressed. This implies that the part of the electronic conductivity of the (Ba,Sr)O layer induced by the dopants also controls the sensitivity for poisoning: the higher the dopant level, the larger the sensitivity for poisoning. Furthermore, the suppression of electrolysis during normal operation largely explains why doped oxide cathodes have a better life performance than non-doped cathodes. Finally a hypothesis on the enhancement of sintering upon doping is presented

  8. 120 MW, 800 MHz Magnicon for a Future Muon Collider

    International Nuclear Information System (INIS)

    Jay L. Hirshfield

    2005-01-01

    Development of a pulsed magnicon at 800 MHz was carried out for the muon collider application, based on experience with similar amplifiers in the frequency range between 915 MHz and 34.3 GHz. Numerical simulations using proven computer codes were employed for the conceptual design, while established design technologies were incorporated into the engineering design. A cohesive design for the 800 MHz magnicon amplifier was carried out, including design of a 200 MW diode electron gun, design of the magnet system, optimization of beam dynamics including space charge effects in the transient and steady-state regimes, design of the drive, gain, and output cavities including an rf choke in the beam exit aperture, analysis of parasitic oscillations and design means to eliminate them, and design of the beam collector capable of 20 kW average power operation

  9. Development of vertical electropolishing process applied on 1300 and 704 MHz superconducting niobium resonators

    Directory of Open Access Journals (Sweden)

    F. Eozénou

    2014-08-01

    Full Text Available An advanced setup for vertical electropolishing of superconducting radio-frequency niobium elliptical cavities has been installed at CEA Saclay. Cavities are vertically electropolished with circulating standard HF-HF-H_{2}SO_{4} electrolytes. Parameters such as voltage, cathode shape, acid flow, and temperature have been investigated. A low voltage (between 6 and 10 V depending on the cavity geometry, a high acid flow (25  L/min, and a low acid temperature (20° C are considered as promising parameters. Such a recipe has been tested on single-cell and nine-cell International Linear Collider (ILC as well as 704 MHz five-cell Super Proton Linac (SPL cavities. Single-cell cavities showed similar performances at 1.6 K being either vertically or horizontally electropolished. The applied baking process provides similar benefit. An asymmetric removal is observed with faster removal in the upper half-cells. Multicell cavities (nine-cell ILC and five-cell SPL cavities exhibit a standard Q_{0} value at low and medium accelerating fields though limited by power losses due to field emitted electrons.

  10. 1 MW, 352.2 MHz, CW and Pulsed RF test stand

    International Nuclear Information System (INIS)

    Badapanda, M.K.; Tripathi, Akhilesh; Upadhyay, Rinki; Tyagi, Rajiv; Hannurkar, P.R.

    2011-01-01

    A 1 MW, 352.2 MHz, RF test stand based on Thales make TH 2089 klystron amplifier is being developed at Raja Ramanna Centre for Advanced Technology (RRCAT), Indore for characterization and qualification of RF components, cavities and related subsystems. Provision to vary RF power from 50 kW to 1 MW with adequate flexibility for testing wide range of HV components, RF components and cavities is incorporated in this test stand. The paper presents a brief detail of various power supplies like high voltage cathode bias power supply, modulating anode power supply, filament power supply, electromagnet power supplies and ion pump power supplies along with their interconnections for biasing TH 2089 klystron amplifier. A digital control and interlock system is being developed to realize proper sequence of operation of various power supplies and to monitor the status of crucial parameters in this test set up. This RF test stand will be a unique national facility, capable of providing both CW and pulse RF power for realizing reliable RF power sources for various projects including the development of high energy proton linac under ADSS program of the Department of Atomic Energy. (author)

  11. Surface functionalized hollow silica particles and composites

    KAUST Repository

    Rodionov, Valentin; Khanh, Vu Bao

    2017-01-01

    Composition comprising hollow spherical silica particles having outside particle walls and inside particle walls, wherein the particles have an average particle size of about 10 nm to about 500 nm and an average wall thickness of about 10 nm to about 50 nm; and wherein the particles are functionalized with at least one organic functional group on the outside particle wall, on the inside particle wall, or on both the outside and inside particle walls, wherein the organic functional group is in a reacted or unreacted form. The organic functional group can be epoxy. The particles can be mixed with polymer precursor or a polymer material such as epoxy to form a prepreg or a nanocomposite. Lightweight but strong materials can be formed. Low loadings of hollow particles can be used.

  12. Space Charge Mitigation by Hollow Bunches

    CERN Multimedia

    Oeftiger, AO

    2014-01-01

    To satisfy the requirements of the HL-LHC (High Luminosity Large Hadron Collider), the LHC injector chain will need to supply a higher brightness, i.e. deliver the same transverse beam emittances \\epsilon_{x,y} while providing a higher intensity N. However, a larger number of particles per bunch enhances space charge effects. One approach to mitigate the impact of space charge is to change the longitudinal phase space distribution: hollow bunches feature a depleted bunch centre and a densely populated periphery. Thus, the spatial line density maximum is depressed which ultimately decreases the tune spread imposed by space charge. Therefore, a higher intensity can be accepted while keeping the same overall space charge tune shift. 3 different methods to create hollow bunches in the PSBooster are simulated.

  13. Surface functionalized hollow silica particles and composites

    KAUST Repository

    Rodionov, Valentin

    2017-05-26

    Composition comprising hollow spherical silica particles having outside particle walls and inside particle walls, wherein the particles have an average particle size of about 10 nm to about 500 nm and an average wall thickness of about 10 nm to about 50 nm; and wherein the particles are functionalized with at least one organic functional group on the outside particle wall, on the inside particle wall, or on both the outside and inside particle walls, wherein the organic functional group is in a reacted or unreacted form. The organic functional group can be epoxy. The particles can be mixed with polymer precursor or a polymer material such as epoxy to form a prepreg or a nanocomposite. Lightweight but strong materials can be formed. Low loadings of hollow particles can be used.

  14. Mesoporous hollow spheres from soap bubbling.

    Science.gov (United States)

    Yu, Xianglin; Liang, Fuxin; Liu, Jiguang; Lu, Yunfeng; Yang, Zhenzhong

    2012-02-01

    The smaller and more stable bubbles can be generated from the large parent bubbles by rupture. In the presence of a bubble blowing agent, hollow spheres can be prepared by bubbling a silica sol. Herein, the trapped gas inside the bubble acts as a template. When the porogen, i.e., other surfactant, is introduced, a mesostructured shell forms by the co-assembly with the silica sol during sol-gel process. Morphological evolution emphasizes the prerequisite of an intermediate interior gas flow rate and high exterior gas flow rate for hollow spheres. The method is valid for many compositions from inorganic, polymer to their composites. Copyright © 2011 Elsevier Inc. All rights reserved.

  15. 47 CFR 90.353 - LMS operations in the 902-928 MHz band.

    Science.gov (United States)

    2010-10-01

    ... 47 Telecommunication 5 2010-10-01 2010-10-01 false LMS operations in the 902-928 MHz band. 90.353... operations in the 902-928 MHz band. LMS systems may be authorized within the 902-928 MHz band, subject to the..., scientific, and medical (ISM) devices and radiolocation Government stations that operate in the 902-928 MHz...

  16. 78 FR 42701 - Improving Public Safety Communications in the 800 MHz Band

    Science.gov (United States)

    2013-07-17

    ...] Improving Public Safety Communications in the 800 MHz Band AGENCY: Federal Communications Commission. ACTION...-901 MHz/935- 940 MHz band (900 MHz B/ILT Band) to allow a qualified entity to file an application for..., manufacturing, energy) to non-commercial (e.g., clerical, educational, philanthropic, medical). In 2004, the...

  17. 77 FR 22720 - Service Rules for Advanced Wireless Services in the 2000-2020 MHz and 2180-2200 MHz Bands, etc.

    Science.gov (United States)

    2012-04-17

    ... operations in 1930-1995 MHz and uplink operations in 2000-2020 MHz. To address this apparent tension, we seek... includes broadcast auxiliary service (BAS) and cable television service (CARS) operations, as well as...

  18. Chalcogenide glass hollow core microstructured optical fibers

    Directory of Open Access Journals (Sweden)

    Vladimir S. eShiryaev

    2015-03-01

    Full Text Available The recent developments on chalcogenide glass hollow core microstructured optical fibers (HC-MOFs are presented. The comparative analysis of simulated optical properties for chalcogenide HC-MOFs of negative-curvature with different size and number of capillaries is given. The technique for the manufacture of microstructured chalcogenide preforms, which includes the assembly of the substrate glass tube and 8-10 capillaries, is described. Further trends to improve the optical transmission in chalcogenide NCHCFs are considered.

  19. Cambridge observations at 38-115 MHz and their implications for space astronomy

    International Nuclear Information System (INIS)

    Saunders, R.

    1987-01-01

    The design and performance of the Cambridge LF telescopes are reviewed. Consideration is given to the 151-MHz 6C telescope, the 38-MHz and 151-MHz LF synthesis telescopes, 81.5-MHz interplanetary scintillation observations with the 3.6-hectare array, long-baseline interferometry at 81.5 MHz, and the use of the Jodrell Bank MERLIN for 151-MHz closure-phase observations of bright sources. The strict limitation on the field mappable at a given resolution in ground-based observations at these frequencies is pointed out, and some outstanding astronomical problems requiring 0.3-30-MHz space observations are listed. 7 references

  20. Formation of hollow atoms above a surface

    Science.gov (United States)

    Briand, Jean Pierre; Phaneuf, Ronald; Terracol, Stephane; Xie, Zuqi

    2012-06-01

    Slow highly stripped ions approaching or penetrating surfaces are known to capture electrons into outer shells of the ions, leaving the innermost shells empty, and forming hollow atoms. Electron capture occurs above and below the surfaces. The existence of hollow atoms below surfaces e.g. Ar atoms whose K and L shells are empty, with all electrons lying in the M and N shells, was demonstrated in 1990 [1]. At nm above surfaces, the excited ions may not have enough time to decay before hitting the surfaces, and the formation of hollow atoms above surfaces has even been questioned [2]. To observe it, one must increase the time above the surface by decelerating the ions. We have for the first time decelerated O^7+ ions to energies as low as 1 eV/q, below the minimum energy gained by the ions due to the acceleration by their image charge. As expected, no ion backscattering (trampoline effect) above dielectric (Ge) was observed and at the lowest ion kinetic energies, most of the observed x-rays were found to be emitted by the ions after surface contact. [4pt] [1] J. P. Briand et al., Phys.Rev.Lett. 65(1990)159.[0pt] [2] J.P. Briand, AIP Conference Proceedings 215 (1990) 513.

  1. A novel synthesis of micrometer silica hollow sphere

    International Nuclear Information System (INIS)

    Pan Wen; Ye Junwei; Ning Guiling; Lin Yuan; Wang Jing

    2009-01-01

    Silica microcapsules (hollow spheres) were synthesized successfully by a novel CTAB-stabilized water/oil emulsion system mediated hydrothermal method. The addition of urea to a solution of aqueous phase was an essential step of the simple synthetic procedure of silica hollow spheres, which leads to the formation of silica hollow spheres with smooth shell during hydrothermal process. The intact hollow spheres were obtained by washing the as-synthesized solid products with distilled water to remove the organic components. A large amount of silanol groups were retained in the hollow spheres by this facile route without calcination. The morphologies and optical properties of the product were characterized by transmission electron microscopy, scanning electron microscopy (SEM) and Fourier transform infrared spectroscopy. Furthermore, on the basis of a series of SEM observations, phenomenological elucidation of a mechanism for the growth of the silica hollow spheres has been presented

  2. Ni hollow spheres as catalysts for methanol and ethanol electrooxidation

    Energy Technology Data Exchange (ETDEWEB)

    Xu, Changwei [Department of Chemistry and Institute of Nanochemistry, Jinan University, Guangzhou 510632 (China); School of Mechanical and Aerospace Engineering, Nanyang Technological University, Singapore 639798 (Singapore); Hu, Yonghong; Rong, Jianhua; Liu, Yingliang [Department of Chemistry and Institute of Nanochemistry, Jinan University, Guangzhou 510632 (China); Jiang, San Ping [School of Mechanical and Aerospace Engineering, Nanyang Technological University, Singapore 639798 (Singapore)

    2007-08-15

    In this paper, we successfully synthesized Ni hollow spheres consisting of needle-like nickel particles by using silica spheres as template with gold nanoparticles seeding method. The Ni hollow spheres are applied to methanol and ethanol electrooxidation in alkaline media. The results show that the Ni hollow spheres give a very high activity for alcohol electrooxidation at a very low nickel loading of 0.10 mg cm{sup -2}. The current on Ni hollow spheres is much higher than that on Ni particles. The onset potential and peak potential on Ni hollow spheres are more negative than that on Ni particles for methanol and ethanol electrooxidation. The Ni hollow spheres may be of great potential in alcohol sensor and direct alcohol fuel cells. (author)

  3. 47 CFR 90.672 - Unacceptable interference to non-cellular 800 MHz licensees from 800 MHz cellular systems or part...

    Science.gov (United States)

    2010-10-01

    ... 47 Telecommunication 5 2010-10-01 2010-10-01 false Unacceptable interference to non-cellular 800 MHz licensees from 800 MHz cellular systems or part 22 Cellular Radiotelephone systems, and within the... Procedures and Process-Unacceptable Interference § 90.672 Unacceptable interference to non-cellular 800 MHz...

  4. Design aspects of 13.56MHz, 1kW, CW-RF oscillator for plasma production

    International Nuclear Information System (INIS)

    Kumar, Sunil; Kadia, Bhavesh; Singh, Raj; Varia, Atul; Srinivas, Y S S; Kulkarni, S V

    2010-01-01

    RF produced plasma has many applications in plasma processing and also it is useful in studying the fundamental characteristics of the plasma. A 1KW RF Hartley oscillator is designed and tested at 13.56 MHz. This has been built at RF section of Institute for Plasma Research by using EIMAC (3CX1200A7) triode tube. The RF source is operated in the grounded cathode mode. Triode 3CX1200A7 is operated in class AB and the feedback is Cathode grounded. The tube has sufficient margin in terms of plate dissipation and Grid dissipation that makes it suitable to withstand momentarily load mismatch. To optimize the RF source along with HVDC power supply many mechanical and electrical aspects have been thought of to enhance the overall quality of the system. This source mainly has three sections (The RF section, HVDC Power supply and soft start Filament Power supply). The system is compact and is housed in a 80 cm x 60 cm x 1800 cm aluminum panel. This paper describes the specifications, design criteria, circuit used, operating parameters of 1KW Oscillator along with HVDC power supply with necessary interlocks, tests conducted and results obtained of this 1 KW grounded grid Hartley Oscillator on 50 ohm dummy load. This system has been tested for 8 hours of continuous operation without any appreciable deterioration of the RF output power.

  5. Review of Synthetic Methods to Form Hollow Polymer Nanocapsules

    Energy Technology Data Exchange (ETDEWEB)

    Barker, Madeline T. [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)

    2014-03-13

    Syntactic foams have grown in interest due to the widened range of applications because of their mechanical strength and high damage tolerance. In the past, hollow glass or ceramic particles were used to create the pores. This paper reviews literature focused on the controlled synthesis of hollow polymer spheres with diameters ranging from 100 –200 nm. By using hollow polymer spheres, syntactic foams could reach ultra-low densities.

  6. Batteries: Overview of Battery Cathodes

    Energy Technology Data Exchange (ETDEWEB)

    Doeff, Marca M

    2010-07-12

    The very high theoretical capacity of lithium (3829 mAh/g) provided a compelling rationale from the 1970's onward for development of rechargeable batteries employing the elemental metal as an anode. The realization that some transition metal compounds undergo reductive lithium intercalation reactions reversibly allowed use of these materials as cathodes in these devices, most notably, TiS{sub 2}. Another intercalation compound, LiCoO{sub 2}, was described shortly thereafter but, because it was produced in the discharged state, was not considered to be of interest by battery companies at the time. Due to difficulties with the rechargeability of lithium and related safety concerns, however, alternative anodes were sought. The graphite intercalation compound (GIC) LiC{sub 6} was considered an attractive candidate but the high reactivity with commonly used electrolytic solutions containing organic solvents was recognized as a significant impediment to its use. The development of electrolytes that allowed the formation of a solid electrolyte interface (SEI) on surfaces of the carbon particles was a breakthrough that enabled commercialization of Li-ion batteries. In 1990, Sony announced the first commercial batteries based on a dual Li ion intercalation system. These devices are assembled in the discharged state, so that it is convenient to employ a prelithiated cathode such as LiCoO{sub 2} with the commonly used graphite anode. After charging, the batteries are ready to power devices. The practical realization of high energy density Li-ion batteries revolutionized the portable electronics industry, as evidenced by the widespread market penetration of mobile phones, laptop computers, digital music players, and other lightweight devices since the early 1990s. In 2009, worldwide sales of Li-ion batteries for these applications alone were US$ 7 billion. Furthermore, their performance characteristics (Figure 1) make them attractive for traction applications such as

  7. Acceleration performance of a 50-MHz split coaxial RFQ and the design of a 25.5-MHz prototype

    International Nuclear Information System (INIS)

    Tokuda, N.; Arai, S.; Fukushima, T.; Morimoto, T.; Tojyo, E.

    1989-03-01

    Acceleration tests on a 50-MHz split coaxial RFQ have been conducted at INS. The 2-m long RFQ has accelerated protons from 2 to 60 keV. The experimental results concerning beam emittance and transmission efficiency agree with predictions of a computer simulation. Following this success, we are fabricating a 25.5-MHz prototype of 2-m long. The issues of the study are to establish a structure standing a high-power operation and to accelerate heavy ions with a charge-to-mass ratio larger than 1/30. (author)

  8. Manufacturing hollow obturator with resilient denture liner on post hemimaxillectomy

    Directory of Open Access Journals (Sweden)

    Michael Josef Kridanto Kamadjaja

    2006-03-01

    Full Text Available A resilient denture liner is placed in the part of the hollow obturator base that contacts to post hemimaxillectomy mucosa. Replacing the resilient denture liner can makes the hollow obturator has an intimate contact with the mucosa, so it can prevents the mouth liquid enter to the cavum nasi and sinus, also eliminates painful because of using the hollow obturator. Resilient denture liner is a soft and resilient material that applied to the fitting surface of a denture in order to allow a more distribution of load. A case was reported about using the hollow obturator with resilient denture liner on post hemimaxillectomy to overcome these problems.

  9. Complex Hollow Nanostructures: Synthesis and Energy-Related Applications.

    Science.gov (United States)

    Yu, Le; Hu, Han; Wu, Hao Bin; Lou, Xiong Wen David

    2017-04-01

    Hollow nanostructures offer promising potential for advanced energy storage and conversion applications. In the past decade, considerable research efforts have been devoted to the design and synthesis of hollow nanostructures with high complexity by manipulating their geometric morphology, chemical composition, and building block and interior architecture to boost their electrochemical performance, fulfilling the increasing global demand for renewable and sustainable energy sources. In this Review, we present a comprehensive overview of the synthesis and energy-related applications of complex hollow nanostructures. After a brief classification, the design and synthesis of complex hollow nanostructures are described in detail, which include hierarchical hollow spheres, hierarchical tubular structures, hollow polyhedra, and multi-shelled hollow structures, as well as their hybrids with nanocarbon materials. Thereafter, we discuss their niche applications as electrode materials for lithium-ion batteries and hybrid supercapacitors, sulfur hosts for lithium-sulfur batteries, and electrocatalysts for oxygen- and hydrogen-involving energy conversion reactions. The potential superiorities of complex hollow nanostructures for these applications are particularly highlighted. Finally, we conclude this Review with urgent challenges and further research directions of complex hollow nanostructures for energy-related applications. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  10. Hollow spheres: crucial building blocks for novel nanostructures and nanophotonics

    Directory of Open Access Journals (Sweden)

    Zhong Kuo

    2018-03-01

    Full Text Available In this review, we summarize the latest developments in research specifically derived from the unique properties of hollow microspheres, in particular, hollow silica spheres with uniform shells. We focus on applications in nanosphere (colloidal lithography and nanophotonics. The lithography from a layer of hollow spheres can result in nanorings, from a multilayer in unique nano-architecture. In nanophotonics, disordered hollow spheres can result in antireflection coatings, while ordered colloidal crystals (CCs of hollow spheres exhibit unique refractive index enhancement upon infiltration, ideal for optical sensing. Furthermore, whispering gallery mode (WGM inside the shell of hollow spheres has also been demonstrated to enhance light absorption to improve the performance of solar cells. These applications differ from the classical applications of hollow spheres, based only on their low density and large surface area, such as catalysis and chemical sensing. We provide a brief overview of the synthesis and self-assembly approaches of the hollow spheres. We elaborate on their unique optical features leading to defect mode lasing, optomicrofluidics, and the existence of WGMs inside shell for light management. Finally, we provide a perspective on the direction towards which future research relevant to hollow spheres might be directed.

  11. Hollow spheres: crucial building blocks for novel nanostructures and nanophotonics

    Science.gov (United States)

    Zhong, Kuo; Song, Kai; Clays, Koen

    2018-03-01

    In this review, we summarize the latest developments in research specifically derived from the unique properties of hollow microspheres, in particular, hollow silica spheres with uniform shells. We focus on applications in nanosphere (colloidal) lithography and nanophotonics. The lithography from a layer of hollow spheres can result in nanorings, from a multilayer in unique nano-architecture. In nanophotonics, disordered hollow spheres can result in antireflection coatings, while ordered colloidal crystals (CCs) of hollow spheres exhibit unique refractive index enhancement upon infiltration, ideal for optical sensing. Furthermore, whispering gallery mode (WGM) inside the shell of hollow spheres has also been demonstrated to enhance light absorption to improve the performance of solar cells. These applications differ from the classical applications of hollow spheres, based only on their low density and large surface area, such as catalysis and chemical sensing. We provide a brief overview of the synthesis and self-assembly approaches of the hollow spheres. We elaborate on their unique optical features leading to defect mode lasing, optomicrofluidics, and the existence of WGMs inside shell for light management. Finally, we provide a perspective on the direction towards which future research relevant to hollow spheres might be directed.

  12. Preparation of TiO2 hollow fibers using poly(vinylidene fluoride) hollow fiber microfiltration membrane as a template

    International Nuclear Information System (INIS)

    Lu Haiqiang; Zhang Lixiong; Xing Weihong; Wang Huanting; Xu Nanping

    2005-01-01

    TiO 2 hollow fibers were successfully prepared by using poly(vinylidene fluoride) hollow fiber microfiltration membrane as a template. The preparation procedure includes repeated impregnation of the TiO 2 precursor in the pores of the polymeric membrane, and calcination to burn off the template, producing the TiO 2 hollow fibers. The TiO 2 hollow fibers were characterized by X-ray diffraction (XRD) and scanning electron microscopy (SEM). TiO 2 hollow fibers with other structures, such as honeycomb monolith and spring, were also prepared by preshaping the polymeric membranes into the honeycomb structure and spring, respectively. The phase structure of the TiO 2 hollow fibers could be readily adjusted by changing the calcination temperature

  13. Design Of Photovoltaic Powered Cathodic Protection System

    Directory of Open Access Journals (Sweden)

    Golina Samir Adly

    2017-07-01

    Full Text Available The corrosion caused by chemical reaction between metallic structures and surrounding mediums such as soil or water .the CP cathodic protection system is used to protect metallic structure against corrosion. Cathodic protection CP used to minimize corrosion by utilizing an external source of electrical current which forces the entire structure to become a cathode. There are two Types of cathodic protection system Galvanic current Impressed current.the Galvanic current is called a sacrificial anode is connected to the protected structure cathode through a DC power supply. In Galvanic current system a current passes from the sacrificing anode to the protected structure .the sacrificial anode is corroded rather than causing the protected structure corrosion .protected structure requires a constant current to stop the corrosion which determined by area structure metal and the surrounding medium. The rains humidity are decrease soil resistivity and increase the DC current .The corrosion and over protection resulting from increase in the DC current is harmful for the metallic structure. This problem can be solved by conventional cathodic protection system by manual adjustment of DC voltage periodically to obtain a constant current .the manual adjustment of DC voltage depends on experience of the technician and using the accuracy of the measuring equipment. The errors of measuring current depend on error from the technician or error from the measuring equipment. the corrosion of structure may occur when the interval between two successive adjustment is long .An automatically regulated cathodic protection system is used to overcome problems from conventional cathodic protection system .the regulated cathodic protection system adjust the DC voltage of the system automatically when it senses the variations of surrounding medium resistivity so the DC current is constant at the required level.

  14. MEMS Tunable Antennas to Address LTE 600 MHz-bands

    DEFF Research Database (Denmark)

    Barrio, Samantha Caporal Del; Morris, Art; Pedersen, Gert Frølund

    2015-01-01

    The broadcast television spectrum around 600 MHz has been freed in the united states and will be put for auction to wireless carriers in 2015. The newest generation of mobile communication standards will be deployed on these newly available bands, to provide mobile device users with an enhanced c...

  15. Charge domain filter operating up to 20 MHz clock frequency

    NARCIS (Netherlands)

    Gal, R.A.J.; Wallinga, Hans

    1983-01-01

    An analog sampled data low pass third order Butterworth filter has been realised in a buried channel CCD technology. This Charge Domain Filter, composed of transversal and recursive CCD filter sections, has been tested at clock frequencies up to 20 MHz.

  16. Calibration of SAR probes in waveguide at 900 MHz

    International Nuclear Information System (INIS)

    Jokela, K.; Puranen, L.; Hyysalo, P.

    1998-01-01

    The radiation safety tests for hand-held mobile phones require precise calibration of the small electric field probes used for the measurement of SAR in phantoms simulating the human body. In this study a calibration based on a rectangular waveguide was developed for SAR calibrations at 900 MHz

  17. 500 MHz transient digitizers based on GaAs CCDs

    International Nuclear Information System (INIS)

    Bryman, D.; Cresswell, J.V.; LeNoble, M.; Poutissou, R.

    1990-10-01

    A wide bandwidth transient digitizer based on a recently produced gallium arsenide charged coupled device is under development. The CCDs have 128 pixels and operate at 500 MHz. Initial testing of prototype modules in Experiment 787 at Brookhaven National Laboratory is reported. (Author) (8 refs., 10 figs.)

  18. MIMOSA. A 32 channel 40 MHz Camac scaler

    International Nuclear Information System (INIS)

    Beer, A.; Bourgeois, F.; Critin, G.

    1981-01-01

    This report describes a 32 channel, 24 bit, 40 MHz single width Camac scaler based on the memory increment technique. The characteristics of the module are given and its logic is briefly described. Circuit diagrams and component lists are given. (orig.)

  19. Status of 174 MHz RF system for BEP

    International Nuclear Information System (INIS)

    Biryuchevsky, Yu.A.; Gorniker, E.I.; Kendjebulatov, E.K.; Krutikhin, S.A.; Kurkin, G.Ya.; Petrov, V.M.; Pilan, A.M.

    2012-01-01

    The new RF system for the BEP storage ring (which is an injector of VEPP-2000 accelerating complex) will increase the particles energy in the BEP from 0.9 to 1 GeV. RF system operates at a frequency of 174 MHz and consists of an accelerating cavity, RF power generator and control system.

  20. Cathodic behavior of zirconium in aqueous solutions

    International Nuclear Information System (INIS)

    Hine, F.; Yasuda, M.; Sato, H.

    1977-01-01

    The electrochemical behavior of Zr was studied by polarization measurements. The surface oxide and zirconium hydride formed by cathodic polarization of Zr have been examined by X-ray, SEM, and a hardness tester. Zirconium hydride would form on Zr cathode after the surface oxide is reduced at the potential, which is several hundred mV more noble than the predicted value shown by the Pourbaix diagram. The parameters for the hydrogen evolution reaction on the hydride formed Zr cathode differs from that on the oxide covered surface, which means that hydrogen evolution takes place on both surfaces under a different mechanism, while details are still veiled at present

  1. Rechargeable lithium/polymer cathode batteries

    Science.gov (United States)

    Osaka, Tetsuya; Nakajima, Toshiki; Shiota, Koh; Owens, Boone B.

    1989-06-01

    Polypyrrole (PPy) and polyaniline (PAn) were investigated for cathode materials of rechargeable lithium batteries. PPy films prepared with PF6(-) anion and/or platinum substrate precoated with nitrile butadiene rubber (NBR) were excellent cathode materials because of rough and/or highly oriented film structure. PAn films were successfully prepared from non-aqueous propylene carbonate solution containing aniline, CF3COOH and lithium perchlorate. Its acidity strongly affects the anion doping-undoping behavior. The PAn cathode prepared in high acidic solution (e.g., 4:1 ratio of acid:aniline) gives the excellent battery performance.

  2. Cold cathode diode X-ray source

    International Nuclear Information System (INIS)

    Cooperstein, G.; Lanza, R.C.; Sohval, A.R.

    1983-01-01

    A cold cathode diode X-ray source for radiation imaging, especially computed tomography, comprises a rod-like anode and a generally cylindrical cathode, concentric with the anode. The spacing between anode and cathode is so chosen that the diode has an impedance in excess of 100 ohms. The anode may be of tungsten, or of carbon with a tungsten and carbon coating. An array of such diodes may be used with a closely packed array of detectors to produce images of rapidly moving body organs, such as the beating heart. (author)

  3. Plasma distribution of cathodic ARC deposition system

    International Nuclear Information System (INIS)

    Anders, S.; Raoux, S.; Krishnan, K.; MacGill, R.A.; Brown, I.G.

    1996-01-01

    The plasma distribution using a cathodic arc plasma source with and without magnetic macroparticle filter has been determined by depositing on a transparent plastic substrate and measuring the film absorption. It was found that the width of the distribution depends on the arc current, and it also depends on the cathode material which leads to a spatial separation of the elements when an alloy cathode is used. By applying a magnetic multicusp field near the exit of the magnetic filter, it was possible to modify the plasma distribution and obtain a flat plasma profile with a constant and homogeneous elemental distribution

  4. Cathode protection for underground steel tanks

    International Nuclear Information System (INIS)

    Angelovski, Zoran

    1998-01-01

    Cathodic protection of underground petroleum storage tanks and piping systems is acceptable for both economic and ecological reasons. With out the cathodic protection of underground steel reservoirs, short time after the exploitation, there was a bore as a result of underground corrosion. The bore causes ecological consequences and at the same time its repair needs big investments. Furthermore, there are great number of tanks placed near cities, so in the future this problem needs a special attention in order to preserve ecological surrounding. The topic of this paper is underground corrosion as well as cathodic protection of steel tanks for oil derivatives storage. (author)

  5. Cyclotron resonance in a cathode ray tube

    International Nuclear Information System (INIS)

    Gherbanovschi, N.; Tanasa, M.; Stoican, O.

    2002-01-01

    Absorption of the RF energy by the electron beam in a cathode ray tube due to the cyclotron resonance is described. The cathode ray tube is placed within a Helmholtz coils system supplied by a sawtooth current generator. In order to generate RF field and to detect RF absorption a gate dip-meter equipped with a FET transistor is used. The bias voltage variations of the FET transistors as a function of the magnetic field are recorded. The operating point of the cathode ray tube has been chosen so that the relaxation oscillations of the detection system can be observed. (authors)

  6. Hall Current Plasma Source Having a Center-Mounted or a Surface-Mounted Cathode

    Science.gov (United States)

    Martinez, Rafael A. (Inventor); Williams, John D. (Inventor); Moritz, Jr., Joel A. (Inventor); Farnell, Casey C. (Inventor)

    2018-01-01

    A miniature Hall current plasma source apparatus having magnetic shielding of the walls from ionized plasma, an integrated discharge channel and gas distributor, an instant-start hollow cathode mounted to the plasma source, and an externally mounted keeper, is described. The apparatus offers advantages over other Hall current plasma sources having similar power levels, including: lower mass, longer lifetime, lower part count including fewer power supplies, and the ability to be continuously adjustable to lower average power levels using pulsed operation and adjustment of the pulse duty cycle. The Hall current plasma source can provide propulsion for small spacecraft that either do not have sufficient power to accommodate a propulsion system or do not have available volume to incorporate the larger propulsion systems currently available. The present low-power Hall current plasma source can be used to provide energetic ions to assist the deposition of thin films in plasma processing applications.

  7. Synthesis of V2O5 microspheres by spray pyrolysis as cathode material for supercapacitors

    Science.gov (United States)

    Yin, Zhendong; Xu, Jie; Ge, Yali; Jiang, Qiaoya; Zhang, Yaling; Yang, Yawei; Sun, Yuping; Hou, Siyu; Shang, Yuanyuan; Zhang, Yingjiu

    2018-03-01

    Vanadium oxide (V2O5) microspheres have attracted considerable attention in the energy field due to their unique properties such as high stability and electrochemical activity. Here, massive V2O5 microspheres with smooth surface, hollow cavity and uniform particle sizes (0.4–1.5 μm), were synthesized by a facile spray pyrolysis process. Post-treatment at predefined temperatures effectively turned the microsphere shell into stacked nanorods with widths of 100 nm and lengths of 500 nm when processed at 500 °C for 3 h under nitrogen atmosphere, with enhanced crystallinity. When applied as cathode materials for supercapacitors, the post-treated V2O5 microspheres at 500 °C exhibited improved specific capacitance and longer discharge time. This is an effective method to manufacture massive V2O5 microspheres with tailored structure and potential applications in high-performance energy storage materials.

  8. Laser absorption spectroscopy for measurement of He metastable atoms of a microhollow cathode plasma

    Science.gov (United States)

    Ueno, Keisuke; Kamebuchi, Kenta; Kakutani, Jiro; Matsuoka, Leo; Namba, Shinichi; Fujii, Keisuke; Shikama, Taiichi; Hasuo, Masahiro

    2018-01-01

    We generated a 0.3-mm-diameter DC, hollow-cathode helium discharge in a gas pressure range of 10-80 kPa. In discharge plasmas, we measured position-dependent laser absorption spectra for helium 23S1-23P0 transition with a spatial resolution of 55 µm. From the results of the analysis of the measured spectra using Voigt functions and including both the Doppler and collision broadening, we produced two-dimensional maps of the metastable 23S1 atomic densities and gas temperatures of the plasmas. We found that, at all pressures, the gas temperatures were approximately uniform in space with values in the range of 400-1500 K and the 23S1 atomic densities were ˜1019 m-3. We also found that the two-dimensional density distribution profiles became ring-shaped at high gas pressures, which is qualitatively consistent with the two-dimensional fluid simulation results.

  9. RF Electron Gun with Driven Plasma Cathode

    CERN Document Server

    Khodak, Igor

    2005-01-01

    It's known that RF guns with plasma cathodes based on solid-state dielectrics are able to generate an intense electron beam. In this paper we describe results of experimental investigation of the single cavity S-band RF gun with driven plasma cathode. The experimental sample of the cathode based on ferroelectric ceramics has been designed. Special design of the cathode permits to separate spatially processes of plasma development and electron acceleration. It has been obtained at RF gun output electron beam with particle energy ~500 keV, pulse current of 4 A and pulse duration of 80 ns. Results of experimental study of beam parameters are referred in. The gun is purposed to be applied as the intense electron beam source for electron linacs.

  10. Rare earth oxide doping in oxide cathodes

    International Nuclear Information System (INIS)

    Engelsen, Daniel den; Gaertner, Georg

    2006-01-01

    The effect on life performance and poisoning with O 2 by doping oxide cathodes with rare earth oxides and pseudo rare earth oxides, notably yttria, is qualitatively explained in terms of electrolysis of BaO during emission of electrons. Doped cathodes show less electrolysis and consume therefore less Ba during life: consequently, doped cathodes have a better life performance. However, the lower Ba-production makes doped cathodes more sensitive to oxygen poisoning. The experimentally found relation between conductivity and yttria concentration was the motive to propose a new model for the crystal imperfections in BaO. In this new imperfection model most Y 3+ -ions will combine with barium vacancies, therefore, the increase of the conductivity is modest and also the effect on the position of the Fermi level is modest. By assuming a combination of bulk and surface conductivity, the agreement between experiment and theory can be improved further

  11. Concentration changes due to cathodic protection

    NARCIS (Netherlands)

    Gellings, P.J.

    1978-01-01

    By solving the appropriate diffusion equations the concentration changes are calculated in the environment of underground structures protected cathodically. It is shown that these changes are negligible under all practical circumstances.

  12. Hollow mandrin facilitates external ventricular drainage placement.

    Science.gov (United States)

    Heese, O; Regelsberger, J; Kehler, U; Westphal, M

    2005-07-01

    Placement of ventricular catheters is a routine procedure in neurosurgery. Ventricle puncture is done using a flexible ventricular catheter stabilised by a solid steel mandrin in order to improve stability during brain penetration. A correct catheter placement is confirmed after removing the solid steel mandrin by observation of cerebrospinal fluid (CSF) flow out of the flexible catheter. Incorrect placement makes further punctures necessary. The newly developed device allows CSF flow observation during the puncture procedure and in addition precise intracranial pressure (ICP) measurement. The developed mandrin is hollow with a blunt tip. On one side 4-5 small holes with a diameter of 0.8 mm are drilled corresponding exactly with the holes in the ventricular catheter, allowing CSF to pass into the hollow mandrin as soon as the ventricle is reached. By connecting a small translucent tube at the distal portion of the hollow mandrin ICP can be measured without loss of CSF. The system has been used in 15 patients with subarachnoid haemorrhage (SAH) or intraventricular haemeorrhage (IVH) and subsequent hydrocephalus. The new system improved the external ventricular drainage implantation procedure. In all 15 patients catheter placement was correct. ICP measurement was easy to perform immediately at ventricle puncture. In 4 patients at puncture no spontaneous CSF flow was observed, therefore by connecting a syringe and gentle aspiration of CSF correct placement was confirmed in this unexpected low pressure hydrocephalus. Otherwise by using the conventional technique further punctures would have been necessary. Advantages of the new technique are less puncture procedures with a lower risk of damage to neural structures and reduced risk of intracranial haemorrhages. Implantation of the ventricular catheter to far into the brain can be monitored and this complication can be overcome. Using the connected pressure monitoring tube an exact measurement of the opening

  13. Hollow-Fiber Spacesuit Water Membrane Evaporator

    Science.gov (United States)

    Bue, Grant; Trevino, Luis; Tsioulos, Gus; Mitchell, Keith; Settles, Joseph

    2013-01-01

    The hollow-fiber spacesuit water membrane evaporator (HoFi SWME) is being developed to perform the thermal control function for advanced spacesuits and spacecraft to take advantage of recent advances in micropore membrane technology in providing a robust, heat-rejection device that is less sensitive to contamination than is the sublimator. After recent contamination tests, a commercial-off-the-shelf (COTS) micro porous hollow-fiber membrane was selected for prototype development as the most suitable candidate among commercial hollow-fiber evaporator alternatives. An innovative design that grouped the fiber layers into stacks, which were separated by small spaces and packaged into a cylindrical shape, was developed into a full-scale prototype for the spacesuit application. Vacuum chamber testing has been performed to characterize heat rejection as a function of inlet water temperature and water vapor back-pressure, and to show contamination resistance to the constituents expected to be found in potable water produced by the wastewater reclamation distillation processes. Other tests showed tolerance to freezing and suitability to reject heat in a Mars pressure environment. In summary, HoFi SWME is a lightweight, compact evaporator for heat rejection in the spacesuit that is robust, contamination- insensitive, freeze-tolerant, and able to reject the required heat of spacewalks in microgravity, lunar, and Martian environments. The HoFi is packaged to reject 810 W of heat through 800 hours of use in a vacuum environment, and 370 W in a Mars environment. The device also eliminates free gas and dissolved gas from the coolant loop.

  14. Electrodeposition of uranium in stirred liquid cadmium cathode

    International Nuclear Information System (INIS)

    Koyama, T.; Tanaka, H.

    1997-01-01

    The electrodeposition of U in a liquid Cd cathode was known to be hampered by the formation of dendritic U on the Cd surface. Electrotransports of uranium to the stirred liquid Cd cathode were carried out at 773 K for different cathode current densities and different Reynolds number of stirring. The maximum amount of U taken in the liquid Cd cathode without forming dendrites was found to increase with an increasing Reynolds number of stirring and decrease with increasing cathode current density. (orig.)

  15. Multipacting Analysis of a Quarter Wave Choke Joint used for Insertion of a Demountable Cathode into a SRF Photoinjector

    International Nuclear Information System (INIS)

    A. Burrill; I. Ben-Zvi; M. D. Cole; J. Rathke; P. Kneisel; R. Manus; R. A. Rimmer

    2007-01-01

    The multipacting phenomena in accelerating structures and coaxial lines are well documented and methods of mitigating or suppressing it are understood. The multipacting that occurs in a quarter wave choke joint designed to mount a cathode insertion stalk into a superconducting RF photoinjector has been analyzed via calculations and experimental measurements and the effect of introducing multipacting suppression grooves into the structure is analyzed. Several alternative choke joint designs are analyzed and suggestions made regarding future choke joint development. Furthermore, the problems encountered in cleaning the choke joint surfaces, factors important in changes to the secondary electron yield, are discussed and evaluated. This design is being implemented on the BNL 1.3 GHz photoinjector, previously used for measurement of the quantum efficiency of bare Nb, to allow for the introduction of other cathode materials for study, and to verify the design functions properly prior to constructing our 703 MHz photoinjector with a similar choke joint design

  16. Porous-wall hollow glass microspheres as carriers for biomolecules

    Science.gov (United States)

    Li, Shuyi; Dynan, William S; Wicks, George; Serkiz, Steven

    2013-09-17

    The present invention includes compositions of porous-wall hollow glass microspheres and one or more biomolecules, wherein the one or more biomolecules are positioned within a void location within the hollow glass microsphere, and the use of such compositions for the diagnostic and/or therapeutic delivery of biomolecules.

  17. Fabrication of Closed Hollow Bulb Obturator Using Thermoplastic Resin Material

    Directory of Open Access Journals (Sweden)

    Bidhan Shrestha

    2015-01-01

    Full Text Available Purpose. Closed hollow bulb obturators are used for the rehabilitation of postmaxillectomy patients. However, the time consuming process, complexity of fabrication, water leakage, and discoloration are notable disadvantages of this technique. This paper describes a clinical report of fabricating closed hollow bulb obturator using a single flask and one time processing method for an acquired maxillary defect. Hard thermoplastic resin sheet has been used for the fabrication of hollow bulb part of the obturator. Method. After fabrication of master cast conventionally, bulb and lid part of the defect were formed separately and joined by autopolymerizing acrylic resin to form one sized smaller hollow body. During packing procedure, the defect area was loaded with heat polymerizing acrylic resin and then previously fabricated smaller hollow body was adapted over it. The whole area was then loaded with heat cure acrylic. Further processes were carried out conventionally. Conclusion. This technique uses single flask which reduces laboratory time and makes the procedure simple. The thickness of hollow bulb can be controlled and light weight closed hollow bulb prosthesis can be fabricated. It also minimizes the disadvantages of closed hollow bulb obturator such as water leakage, bacterial infection, and discoloration.

  18. Facile synthesis of aluminum-doped LiNi{sub 0.5}Mn{sub 1.5}O{sub 4} hollow microspheres and their electrochemical performance for high-voltage Li-ion batteries

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Xiaolin, E-mail: liu_x_l@sina.cn [College of Material Science and Engineering, Jiangxi University of Science and Technology, Ganzhou 341000, Jiangxi (China); Li, Dan; Mo, Qiaoling; Guo, Xiaoyu; Yang, Xiaoxiao [College of Material Science and Engineering, Jiangxi University of Science and Technology, Ganzhou 341000, Jiangxi (China); Chen, Guoxin, E-mail: gxchen@nimte.ac.cn [Ningbo Institute of Material Technology and Engineering, Chinese Academy of Sciences, Ningbo 315201, Zhejiang (China); Zhong, Shengwen [College of Material Science and Engineering, Jiangxi University of Science and Technology, Ganzhou 341000, Jiangxi (China)

    2014-10-01

    Graphical abstract: LiNi{sub 0.5}Mn{sub 1.5}O{sub 4} and Al doped LiNi{sub 0.5}Mn{sub 1.5}O{sub 4} hollow microspheres as 5 V cathodes are prepared by templated transformation method using monodisperse MnCO{sub 3} microspheres as precursor. As a cathodic material for high voltage lithium ion batteries, the as-synthesized LiNi{sub 0.5}Mn{sub 1.5}O{sub 4} and Al doped LiNi{sub 0.5}Mn{sub 1.5}O{sub 4} hollow microspheres are investigated by galvanostatic cycling (GC) approach to evaluate their electrochemical properties in the range of 2.7–4.8 V vs. Li/Li{sup +} at the current rate 1 C. - Highlights: • LNMO and LANMO hollow microspheres are synthesized by template method. • The as-synthesized hollow microspheres have particle-size of 2 μm. • The hollow structure is responsible for improved electrochemical performance. - Abstract: This paper presents the preparation of LiNi{sub 0.5}Mn{sub 1.5}O{sub 4} and aluminum (Al) doped LiNi{sub 0.5}Mn{sub 1.5}O{sub 4} hollow microspheres as 5 V cathodes using monodisperse MnCO{sub 3} microspheres as precursor and template, which were synthesized using MnSO{sub 4}·H{sub 2}O, NaHCO{sub 3} and ethanol in water at room temperature. XRD and morphology characterization results indicated that the as-prepared LiNi{sub 0.5}Mn{sub 1.5}O{sub 4} and Al doped LiNi{sub 0.5}Mn{sub 1.5}O{sub 4} were both spinel structure, and have particle sizes of 2–3 μm. The cathode electrochemical properties of LiNi{sub 0.5}Mn{sub 1.5}O{sub 4} and Al doped LiNi{sub 0.5}Mn{sub 1.5}O{sub 4} hollow microspheres (as 5 V cathodes) were evaluated and compared by galvanostatic cycling (GC) vs. Li/Li{sup +} at the current rate 1 C in 2.7–4.8 V. The specific initial capacities of all samples were in the range of 70–120 mA h g{sup −1}. Compared to undoped LiNi{sub 0.5}Mn{sub 1.5}O{sub 4}, Al doped LiNi{sub 0.5}Mn{sub 1.5}O{sub 4} hollow structures can effectively improve discharge capacity (up to 140 (±5) mA h g{sup −1}) and cycling stability (70

  19. Hydrothermal synthesis of cathode materials

    Science.gov (United States)

    Chen, Jiajun; Wang, Shijun; Whittingham, M. Stanley

    A number of cathodes are being considered for the next generation of lithium ion batteries to replace the expensive LiCoO 2 presently used. Besides the layered oxides, such as LiNi yMn yCo 1-2 yO 2, a leading candidate is lithium iron phosphate with the olivine structure. Although this material is inherently low cost, a manufacturing process that produces electrochemically active LiFePO 4 at a low cost is also required. Hydrothermal reactions are one such possibility. A number of pure phosphates have been prepared using this technique, including LiFePO 4, LiMnPO 4 and LiCoPO 4; this method has also successfully produced mixed metal phosphates, such as LiFe 0.33Mn 0.33Co 0.33PO 4. Ascorbic acid was found to be better than hydrazine or sugar at preventing the formation of ferric ions in aqueous media. When conductive carbons are added to the reaction medium excellent electrochemical behavior is observed.

  20. Fe2O3 hollow sphere nanocomposites for supercapacitor applications

    Science.gov (United States)

    Zhao, Yu; Wen, Yang; Xu, Bing; Lu, Lu; Ren, Reiming

    2018-02-01

    Nanomaterials have attracted increasing interest in electrochemical energy storage and conversion. Hollow sphere Fe2O3 nanocomposites were successfully prepared through facile low temperature water-bath method with carbon sphere as hard template. The morphology and microstructure of samples were characterized by X-ray diffraction (XRD) and Scanning electron microscope (SEM), respectively. Through hydrolysis mechanism, using ferric chloride direct hydrolysis, iron hydroxide coated on the surface of carbon sphere, after high temperature calcination can form the hollow spherical iron oxide materials. Electrochemical performances of the hollow sphere Fe2O3 nanocomposites electrodes were investigated by cyclic voltammery (CV) and galvanostatic charge/discharge. The Pure hollow sphere Fe2O3 nanocomposites achieves a specific capacitance of 125 F g-1 at the current density of 85 mA g-1. The results indicate that the uniform dispersion of hollow ball structure can effectively reduce the particle reunion in the process of charging and discharging.

  1. A novel anaerobic electrochemical membrane bioreactor (AnEMBR) with conductive hollow-fiber membrane for treatment of low-organic strength solutions

    KAUST Repository

    Katuri, Krishna; Werner, Craig M.; Jimenez Sandoval, Rodrigo J.; Chen, Wei; Jeon, Sungil; Logan, Bruce E.; Lai, Zhiping; Amy, Gary L.; Saikaly, Pascal

    2014-01-01

    A new anaerobic treatment system that combined a microbial electrolysis cell (MEC) with membrane filtration using electrically conductive, porous, nickel-based hollow-fiber membranes (Ni-HFMs) was developed to treat low organic strength solution and recover energy in the form of biogas. This new system is called an anaerobic electrochemical membrane bioreactor (AnEMBR). The Ni-HFM served the dual function as the cathode for hydrogen evolution reaction (HER) and the membrane for filtration of the effluent. The AnEMBR system was operated for 70 days with synthetic acetate solution having a chemical oxygen demand (COD) of 320 mg/L. Removal of COD was >95% at all applied voltages tested. Up to 71% of the substrate energy was recovered at an applied voltage of 0.7 V as methane rich biogas (83% CH4; < 1% H2) due to biological conversion of the hydrogen evolved at the cathode to methane. A combination of factors (hydrogen bubble formation, low cathode potential and localized high pH at the cathode surface) contributed to reduced membrane fouling in the AnEMBR compared to the control reactor (open circuit voltage). The net energy required to operate the AnEMBR system at an applied voltage of 0.7 V was significantly less (0.27 kWh/m3) than that typically needed for wastewater treatment using aerobic membrane bioreactors (1-2 kWh/m3).

  2. A novel anaerobic electrochemical membrane bioreactor (AnEMBR) with conductive hollow-fiber membrane for treatment of low-organic strength solutions

    KAUST Repository

    Katuri, Krishna

    2014-11-04

    A new anaerobic treatment system that combined a microbial electrolysis cell (MEC) with membrane filtration using electrically conductive, porous, nickel-based hollow-fiber membranes (Ni-HFMs) was developed to treat low organic strength solution and recover energy in the form of biogas. This new system is called an anaerobic electrochemical membrane bioreactor (AnEMBR). The Ni-HFM served the dual function as the cathode for hydrogen evolution reaction (HER) and the membrane for filtration of the effluent. The AnEMBR system was operated for 70 days with synthetic acetate solution having a chemical oxygen demand (COD) of 320 mg/L. Removal of COD was >95% at all applied voltages tested. Up to 71% of the substrate energy was recovered at an applied voltage of 0.7 V as methane rich biogas (83% CH4; < 1% H2) due to biological conversion of the hydrogen evolved at the cathode to methane. A combination of factors (hydrogen bubble formation, low cathode potential and localized high pH at the cathode surface) contributed to reduced membrane fouling in the AnEMBR compared to the control reactor (open circuit voltage). The net energy required to operate the AnEMBR system at an applied voltage of 0.7 V was significantly less (0.27 kWh/m3) than that typically needed for wastewater treatment using aerobic membrane bioreactors (1-2 kWh/m3).

  3. Characterization of the SPS 800MHz travelling wave cavities.

    CERN Document Server

    Bazyl, Dmitry

    2015-01-01

    It is well known that HOMs in RF cavities are a potentially dangerous source of beam impedance. Therefore, HOMs (both longitudinal and transverse) can drive the beam unstable . The 800MHz cavities of the SPS were studied in the past. However, very little documentation was left behind. Currently, the performance of the SPS is limited by a longitudinal beam instability. In order to study this instability, an accurate impedance model of the whole SPS is needed.

  4. Polarization observations of four southern pulsars at 1560 MHz

    Science.gov (United States)

    Wu, Xin-Ji; Manchester, R. N.; Lyne, A. G.

    1991-12-01

    Some interesting results from the mean pulse polarization observations of four southern pulsars made at the Australian National Radio Astronomy Observatory, Parkes, using the 64-m telescope in June and July, 1988, are presented. The 2 x 16 x 5 MHz filter system from Jodrell Bank has proved excellent in dedispersing the pulse signals and measuring their polarization properties. Data for the four pulsars are given in some detail, and their spectral behavior is discussed.

  5. Status of HLT1 sequence and path towards 30 MHz

    CERN Document Server

    De Cian, Michel; Gligorov, Vladimir; Hasse, Christoph; Hulsbergen, Wouter; Latham, Thomas Edward; Ponce, Sebastien; Quagliani, Renato; Schreiner, Henry Fredrick; Stemmle, Simon Benedikt; Van Tilburg, Jeroen; Zdybal, Milosz Jerzy; Williams, J Michael

    2018-01-01

    We present the current status of the HLT1 reconstruction sequence for the LHCb upgrade, both in terms of the number of events which can be processed per second and the achievable physics performance on a selected range of benchmark modes. We present detailed profiling of the various algorithms, describe the bottlenecks, and outline a strategy towards an HLT1 able to process the LHCb upgrade data at 30 MHz

  6. Effect of 2 MHz ultrasound irradiation on Pisum sativum roots

    International Nuclear Information System (INIS)

    Miller, M.W.; Voorhees, S.M.; Carstensen, E.L.; Kaufman, G.E.

    1976-01-01

    The effect of 2 MHz ultrasound at intensity levels from 2.5 to 22 W/cm 2 on the growth rate and mitotic index of Pisum sativum roots was studied. The ultrasound produced an immediate reduction in the growth rate on the first postexposure day, followed by a gradual recovery to the control value. Ultrasound reduced the root meristem mitotic index. Intensity- and time-dependent relations were found for the growth rate and mitotic index reductions

  7. Design of 1 MHz solid state high frequency power supply

    International Nuclear Information System (INIS)

    Parmar, Darshan Kumar; Singh, N.P.; Gajjar, Sandip

    2015-01-01

    A High Voltage High Frequency (HVHF) Power supply is used for various applications, like AM Transmitters, metallurgical applications, Wireless Power Transfer, RF Ion Sources, etc. The Ion Source for a Neutral beam Injector at ITER-India uses inductively coupled power source at High Frequency (∼ 1 MHz). Switching converter based topology used to generate 1 MHz sinusoidal output is expected to have advantages on efficiency and reliability as compared to traditional RF Tetrode tubes based oscillators. In terms of Power Electronics, thermal and power coupling issues are major challenges at such a high frequency. A conceptual design for a 200 kW, 1 MHz power supply and a prototype design for a 600W source been done. The prototype design is attempted with Class-E amplifier topology where a MOSFET is switched resonantly. The prototype uses two low power modules and a ferrite combiner to add the voltage and power at the output. Subsequently solution with class-D H-Bridge configuration have been evaluated through simulation where module design is stable as switching device do not participate in resonance, further switching device voltage rating is substantially reduced. The rating of the modules is essentially driven by the maximum power handling capacity of the MOSFETs and ferrites in the combiner circuit. The output passive network including resonance tuned network and impedance matching network caters for soft switching and matches the load impedance to 50 ohm respectively. This paper describes the conceptual design of a 200 kW power supply and experimental results of the prototype 600 W, 1 MHz source. (author)

  8. The quiet Sun brightness temperature at 408 MHz

    International Nuclear Information System (INIS)

    Avignon, Y.; Lantos, P.; Palagi, F.; Patriarchi, P.

    1975-01-01

    The flux of the radio quiet Sun and the brightness temperature at 408 MHz (73cm) are derived from measurements with the E-W Nancay interferometer and the E-W arm of the Medicina North Cross. It is shown that the lowest envelopes, which defined the radio quiet Sun, correspond to transits of extended coronal holes across the disk of the Sun. (Auth.)

  9. Development of a high-power 432 MHz DTL

    International Nuclear Information System (INIS)

    Naito, F.; Kato, T.; Takasaki, E.; Yamazaki, Y.; Kawasumi, T.; Suzuki, K.; Iino, Y.

    1992-01-01

    A high-power model of a 432 MHz Drift-Tube Linac is under construction. It will accelerate H - ions from 3 to 5.4 MeV, and is a prototype of the DTL for the Japanese Hadron Project. Several new techniques have been developed for constructing the DTL: fabricating and assembling methods of permanent quadrupole magnet and a drift tube, alignment of the drift tube, and a method of connecting the tanks. (Author) 6 refs., 5 figs

  10. Spectroscopy of radio sources from the Parkes 2700 MHz survey

    International Nuclear Information System (INIS)

    Thompson, D.J.; Djorgovski, S.; De Carvalho, R.

    1990-01-01

    The results of long-slit CCD spectroscopy on 37 objects from the Parkes 2700 MHz survey are presented, with data for an additional two companion objects. Eight of the objects are quasars, six more are AGNs, and five more are radio galaxies. Seventeen of the objects observed are stars and, thus, probable misidentifications. Three objects show featureless spectra and are identified as possible BL Lac objects. Spectra are presented for a total of 20 objects. 20 refs

  11. Prototype 350 MHz niobium spoke-loaded cavities

    International Nuclear Information System (INIS)

    Delayen, J. R.; Kedzie, M.; Mammosser, J.; Piller, C.; Shepard, K. W.

    1999-01-01

    This paper reports the development of 350 MHz superconducting cavities of a spoke-loaded geometry, intended for the velocity range 0.2 < v/c < 0.6. Two prototype single-cell cavities have been designed, one optimized for velocity v/c = 0.4, and the other for v/c = 0.29. Construction of the prototype niobium cavities is nearly complete. Details of the design and construction are discussed, along with the results of cold tests

  12. Prototype 350 MHz niobium spoke-loaded cavities.

    Energy Technology Data Exchange (ETDEWEB)

    Delayen, J. R.; Kedzie, M.; Mammosser, J.; Piller, C.; Shepard, K. W.

    1999-05-10

    This paper reports the development of 350 MHz superconducting cavities of a spoke-loaded geometry, intended for the velocity range 0.2 < v/c < 0.6. Two prototype single-cell cavities have been designed, one optimized for velocity v/c = 0.4, and the other for v/c = 0.29. Construction of the prototype niobium cavities is nearly complete. Details of the design and construction are discussed, along with the results of cold tests.

  13. Design of 1 MHz Solid State High Frequency Power Supply

    Science.gov (United States)

    Parmar, Darshan; Singh, N. P.; Gajjar, Sandip; Thakar, Aruna; Patel, Amit; Raval, Bhavin; Dhola, Hitesh; Dave, Rasesh; Upadhay, Dishang; Gupta, Vikrant; Goswami, Niranjan; Mehta, Kush; Baruah, Ujjwal

    2017-04-01

    High Frequency Power supply (HFPS) is used for various applications like AM Transmitters, metallurgical applications, Wireless Power Transfer, RF Ion Sources etc. The Ion Source for a Neutral beam Injector at ITER-India uses inductively coupled power source at High Frequency (∼1 MHz). Switching converter based topology used to generate 1 MHz sinusoidal output is expected to have advantages on efficiency and reliability as compared to traditional RF Tetrode tubes based oscillators. In terms of Power Electronics, thermal and power coupling issues are major challenges at such a high frequency. A conceptual design for a 200 kW, 1 MHz power supply and a prototype design for a 600 W source been done. The prototype design is attempted with Class-E amplifier topology where a MOSFET is switched resonantly. The prototype uses two low power modules and a ferrite combiner to add the voltage and power at the output. Subsequently solution with Class-D H-Bridge configuration have been evaluated through simulation where module design is stable as switching device do not participate in resonance, further switching device voltage rating is substantially reduced. The rating of the modules is essentially driven by the maximum power handling capacity of the MOSFETs and ferrites in the combiner circuit. The output passive network including resonance tuned network and impedance matching network caters for soft switching and matches the load impedance to 50ohm respectively. This paper describes the conceptual design of a 200 kW high frequency power supply and experimental results of the prototype 600 W, 1 MHz source.

  14. Long-term evaluation of hollow screw and hollow cylinder dental implants : Clinical and radiographic results after 10 years

    NARCIS (Netherlands)

    Telleman, Gerdien; Meijer, Henny J. A.; Raghoebar, Gerry M.

    Background: In 1988, an implant manufacturer offered a new dental implant system, with a wide choice of hollow cylinder (HC) and hollow screw (HS) implants. The purpose of this retrospective study of HS and HC implants was to evaluate clinical and radiographic parameters of peri-implant tissue and

  15. Velocities of Auroral Coherent Echoes At 12 and 144 Mhz

    Science.gov (United States)

    Koustov, A. V.; Danskin, D. W.; Makarevitch, R. A.; Uspensky, M. V.; Janhunen, P.; Nishitani, N.; Nozawa, N.; Lester, M.; Milan, S.

    Two Doppler coherent radar systems are currently working at Hankasalmi, Finland, the STARE and CUTLASS radars operating at 144 MHz and 12 MHz, respectively. The STARE beam 3 is nearly co-located with the CUTLASS beam 5 providing an opportunity for echo velocity comparison along the same direction but at significantly different radar frequencies. In this study we consider one event when STARE radar echoes are detected t the same ranges as CUTLASS radar echoes. The observations are complemented by EISCAT measurements of the ionospheric electric field and elec- tron density behavior at one range of 900 km. Two separate situations are studied; for the first one, CUTLASS observed F-region echoes (including the range of the EIS- CAT measurements) while for the second one CUTLASS observed E-region echoes. In both cases STARE E-region measurements were available. We show that F-region CUTLASS velocities agree well with the convection component along the CUTLASS radar beam while STARE velocities are sometimes smaller by a factor of 2-3. For the second case, STARE velocities are found to be either smaller or larger than CUTLASS velocities, depending on range. Plasma physics of E- and F-region irregularities is dis- cussed in attempt to explain inferred relationship between various velocities. Special attention is paid to ionospheric refraction that is important for the detection of 12-MHz echoes.

  16. Assessment of cutaneous radiation fibrosis by 20 MHz-sonography

    International Nuclear Information System (INIS)

    Gottloeber, P.; Braun-Falco, B.; Plewig, G.; Kerscher, M.; Peter, R.U.; Nadeshina, N.

    1996-01-01

    Radiation fibrosis is the cardinal symptom of the chronicle stage of the cutaneous radiation syndrome. The degree of cutaneous fibrosis can clinically be estimated by palpation. High-frequency 20 MHz-sonography is an established, noninvasive procedure, which renders an exact determination of skin thickness and additionally densitometry is possible. We investigated 15 survivors of the Chernobyl accident in 1986, who developed symptoms of the chronic stage of the cutaneous radiation syndrome. We determined skin thickness and echogenicity of skin areas clinically suggestive of radiation fibrosis before, during and after treatment. 20 MHz-sonography showed a distinct enlargement of the echorich corium and a reduction of the subcutaneous fatty tissue in comparison with the unaffected, contralateral skin, here demonstrating typical features of radiation fibrosis, namely dermal fibrosis and reactive pseudoatrophy and fatty tissue. The histology presented an increase and swelling of the collagen fibers and atypical fibroblastic cells. The patients received treatment with low-dose interferon y (Polyfcron R , 3 x 50μg s.C., three times per week) up to 30 months. A marked reduction of skin thickness and echogenicity reaching nearly normal values could be observed. We conclude that 20 MHz-sonography is an easy to apply, noninvasive, well established procedure to quantify cutaneous radiation fibrosis and to assess therapeutic outcome

  17. The LANSCE 805 MHZ RF System History and Status

    CERN Document Server

    Lynch, Michael; Tallerico, Paul J

    2005-01-01

    The Los Alamos Neutron Science Center (LANSCE) linear accelerator runs at 201.25 MHz for acceleration to 100 MeV. The remainder of the acceleration to 800 MeV is at 805 MHz. This is done with 44 accelerator cavity stages driven by 805 MHz klystrons. Each klystron has a peak power capability of 1.25 MeV. Originally, 97 klystrons were purchased, which was 70 from Varian/CPI and 27 from Litton. The 44 RF systems are laid out in sectors with either 6 or 7 klystrons per sector. The klystrons in each sector are powered from a common HV sytem. The current arrangement uses the Varian/CPI klystrons in 6 of the 7 sectors and Litton klystrons in the remaining sector. With that arrangement there are 38 CPI klystrons installed and 1 spare klystron per sector and 6 Litton klystrons installed in the final sector with 2 spares. The current average life of all of the operating and spare klystrons (52 total) is >112,000 filament hours and >93,000 HV hours. That is three times the typical klystron lifetime today f...

  18. A 2 MHz 3-port analog isolation and fanout module

    International Nuclear Information System (INIS)

    Beadle, E.R.

    1995-01-01

    In many accelerator based data acquisition systems, signal isolation is a necessary feature so ground loops are avoided. Here, a 3-port isolated circuit providing 1:3 fanout, buffering and amplification over a multi-megahertz bandwidth is presented. The circuit accepts a single input and drives 3 independently isolated output channels, up to ± 10 V into 50 ohms. The input and output isolation is supplied via a dual optocoupler, and the power isolation is achieved with DC/DC converters. In each channel, a voltage feedback amplifier is used in combination with the optocoupler to form a transimpedance configuration with the gain-bandwidth product (GBP) set by a pair of resistors. The feedback amplifier linearizes the optocoupler transfer characteristics using a servo technique and also controls the circuit drift, nonlinearity, and bandwidth. The circuit has demonstrated long-term drift of 4 MHz, and a SNR of >55 db in a 1 MHz bandwidth with < 1% THD for a 10 V amplitude sinusoidal input. With few modifications, this design is capable of providing input/output gain and bandwidth in the range of 10--50 MHz

  19. Design of 118 MHz twelfth harmonic cavity of APS PAR

    International Nuclear Information System (INIS)

    Kang, Y.W.; Kustom, R.L.; Bridges, J.F.

    1992-01-01

    Two radio frequency (RF) cavities are needed in the Positron Accumulator Ring (PAR) of the Advanced Photon Source. One is for the first harmonic frequency at 9.8 MHz, and the other is for the twelfth harmonic frequency at 118 MHz. This note reports on the design of the 118 MHz RF cavity. Computer models are used to find the mode frequencies, impedances, Q-factors, and field distributions in the cavity. The computer codes MAFIA, URMEL, and URMEL-T are useful tools which model and simulate the resonance characteristics of a cavity. These codes employ the finite difference method to solve Maxwell's equations. MAFIA is a three-dimensional problem solver and uses square patches to approximate the inner surface of a cavity. URMEL and URMEL-T are two-dimensional problem solvers and use rectangular and triangular meshes, respectively. URMEL-T and MAFIA can handle problems with arbitrary dielectric materials located inside the boundary. The cavity employs a circularly cylindrical ceramic window to limit the vacuum to the beam pipe. The ceramic window used in the modeling will have a wall thickness of 0.9 cm. This wall thickness is not negligible in determining the resonant frequencies of the cavity. In the following, results of two- and three-dimensional modeling of the cavities using the URMEL-T and MAFIA codes are reported

  20. An Automated 476 MHz RF Cavity Processing Facility at SLAC

    CERN Document Server

    McIntosh, P; Schwarz, H

    2003-01-01

    The 476 MHz accelerating cavities currently used at SLAC are those installed on the PEP-II B-Factory collider accelerator. They are designed to operate at a maximum accelerating voltage of 1 MV and are routinely utilized on PEP-II at voltages up to 750 kV. During the summer of 2003, SPEAR3 will undergo a substantial upgrade, part of which will be to replace the existing 358.54 MHz RF system with essentially a PEP-II high energy ring (HER) RF station operating at 476.3 MHz and 3.2 MV (or 800 kV/cavity). Prior to installation, cavity RF processing is required to prepare them for use. A dedicated high power test facility is employed at SLAC to provide the capability of conditioning each cavity up to the required accelerating voltage. An automated LabVIEW based interface controls and monitors various cavity and test stand parameters, increasing the RF fields accordingly such that stable operation is finally achieved. This paper describes the high power RF cavity processing facility, highlighting the features of t...

  1. Reduction of environmental MHz noise for SQUID application

    Energy Technology Data Exchange (ETDEWEB)

    Araya, T. [Graduate School of Engineering Science, Osaka University, 1-3 Machikaneyama, Toyonaka, Osaka 560-8531 (Japan)]. E-mail: araya@sup.ee.es.osaka-u.ac.jp; Kitamura, Y. [Graduate School of Engineering Science, Osaka University, 1-3 Machikaneyama, Toyonaka, Osaka 560-8531 (Japan); Kamishiro, M. [Graduate School of Engineering Science, Osaka University, 1-3 Machikaneyama, Toyonaka, Osaka 560-8531 (Japan); Sakuta, K. [Graduate School of Engineering Science, Osaka University, 1-3 Machikaneyama, Toyonaka, Osaka 560-8531 (Japan); Itozaki, H. [Graduate School of Engineering Science, Osaka University, 1-3 Machikaneyama, Toyonaka, Osaka 560-8531 (Japan)]. E-mail: itozaki@ee.es.osaka-u.ac.jp

    2006-10-01

    It is important to remove large environmental noise in measurement using SQUIDs without magnetic shielding. Active noise control (ANC) is an effective method to remove the environmental noise. The environmental noise has been reduced by the ANC system in the radio frequency region around MHz. The anti-phase waves of the environmental noise should be generated by this system. The ANC system including the phase and amplitude control circuit was developed to make the anti-phase waves in the MHz region. In this paper, sinusoidal waves with a MHz frequency were used as the environmental noise. When a coil antenna was used for a receiver antenna, this ANC system suppressed these sinusoidal waves to the white noise level about 40 dB. When we used a SQUID as a receiver antenna, we also cancelled sinusoidal waves to the white noise level by this system. This shows that the ANC system is useful to reduce an environmental noise when this ANC system is developed to cancel multi-frequency noise.

  2. Reduction of environmental MHz noise for SQUID application

    International Nuclear Information System (INIS)

    Araya, T.; Kitamura, Y.; Kamishiro, M.; Sakuta, K.; Itozaki, H.

    2006-01-01

    It is important to remove large environmental noise in measurement using SQUIDs without magnetic shielding. Active noise control (ANC) is an effective method to remove the environmental noise. The environmental noise has been reduced by the ANC system in the radio frequency region around MHz. The anti-phase waves of the environmental noise should be generated by this system. The ANC system including the phase and amplitude control circuit was developed to make the anti-phase waves in the MHz region. In this paper, sinusoidal waves with a MHz frequency were used as the environmental noise. When a coil antenna was used for a receiver antenna, this ANC system suppressed these sinusoidal waves to the white noise level about 40 dB. When we used a SQUID as a receiver antenna, we also cancelled sinusoidal waves to the white noise level by this system. This shows that the ANC system is useful to reduce an environmental noise when this ANC system is developed to cancel multi-frequency noise

  3. Air Separation Using Hollow Fiber Membranes

    Science.gov (United States)

    Huang, Stephen E.

    2004-01-01

    The NASA Glenn Research Center in partnership with the Ohio Aerospace Institute provides internship programs for high school and college students in the areas of science, engineering, professional administrative, and other technical areas. During the summer of 2004, I worked with Dr. Clarence T. Chang at NASA Glenn Research Center s combustion branch on air separation using hollow fiber membrane technology. . In light of the accident of Trans World Airline s flight 800, FAA has mandated that a suitable solution be created to prevent the ignition of fuel tanks in aircrafts. In order for any type of fuel to ignite, three important things are needed: fuel vapor, oxygen, and an energy source. Two different ways to make fuel tanks less likely to ignite are reformulating the fuel to obtain a lower vapor pressure for the fuel and or using an On Board Inert Gas Generating System (OBIGGS) to inert the Central Wing Tank. goal is to accomplish the mission, which means that the Air Separation Module (ASM) tends to be bulky and heavy. The primary goal for commercial aviation companies is to transport as much as they can with the least amount of cost and fuel per person, therefore the ASM must be compact and light as possible. The plan is to take bleed air from the aircraft s engines to pass air through a filter first to remove particulates and then pass the air through the ASM containing hollow fiber membranes. In the lab, there will be a heating element provided to simulate the temperature of the bleed air that will be entering the ASM and analysis of the separated air will be analyzed by a Gas Chromatograph/Mass Spectrometer (GC/MS). The GUMS will separate the different compounds in the exit streams of the ASM and provide information on the performance of hollow fiber membranes. Hopefully I can develop ways to improve efficiency of the ASM. different types of jet fuel were analyzed and data was well represented on SAE Paper 982485. Data consisted of the concentrations of over

  4. 2013 Estorm - Invited Paper - Cathode Materials Review

    Energy Technology Data Exchange (ETDEWEB)

    Daniel, Claus [ORNL; Mohanty, Debasish [ORNL; Li, Jianlin [ORNL; Wood III, David L [ORNL

    2014-01-01

    The electrochemical potential of cathode materials defines the positive side of the terminal voltage of a battery. Traditionally, cathode materials are the energy-limiting or voltage-limiting electrode. One of the first electrochemical batteries, the voltaic pile invented by Alessandro Volta in 1800 (Phil. Trans. Roy. Soc. 90, 403 431) had a copper-zinc galvanic element with a terminal voltage of 0.76 V. Since then, the research community has increased capacity and voltage for primary (nonrechargeable) batteries and round-trip efficiency for secondary (rechargeable) batteries. Successful secondary batteries have been the lead acid with a lead oxide cathode and a terminal voltage of 2.1 V and later the NiCd with a nickel(III) oxide hydroxide cathode and a 1.2 V terminal voltage. The relatively low voltage of those aqueous systems and the low round-trip efficiency due to activation energies in the conversion reactions limited their use. In 1976, Wittingham (J. Electrochem. Soc., 123, 315) and Besenhard (J Power Sources 1(3), 267) finally enabled highly reversible redox reactions by intercalation of lithium ions instead of by chemical conversion. In 1980, Goodenough and Mizushima (Mater. Res. Bull. 15, 783 789) demonstrated a high-energy and high-power LiCoO2 cathode, allowing for an increase of terminal voltage far beyond 3 V. Over the past four decades, the international research community has further developed cathode materials of many varieties. Current state-of-the-art cathodes demonstrate voltages beyond any known electrolyte stability window, bringing electrolyte research once again to the forefront of battery research.

  5. A Novel Dual-Band Rectenna for Ambient RF Energy Harvesting at GSM 900 MHz and 1800 MHz

    Directory of Open Access Journals (Sweden)

    Dinh Khanh Ho

    2017-06-01

    Full Text Available This paper presents a novel dual-band rectenna for RF energy harvesting system. This rectenna is created from a dual-band antenna and a dual-band rectifier which operates at GSM bands (900 MHz and 1800 MHz. The printed monopole antenna is miniaturized by two meander-lines. The received signal from the receiving antenna is rectified by a voltage double using Schottky diode SMS-7630. The rectifier is optimized for low input power level of -20dBm using harmonic balance. Prototype is designed and fabricated. The simulation is validated by measurement with power conversion efficiency of 20% and 40.8% (in measurement at the input power level of -20dBm. The proposed rectenna has output voltage from 183-415 mV. From the measured results, this rectenna provides the possibility to harvest the ambient electromagnetic energy for powering low-power electronic devices.

  6. Beryllium electrodeposition on aluminium cathode from chloride melts

    International Nuclear Information System (INIS)

    Nichkov, I.F.; Novikov, E.A.; Serebryakov, G.A.; Kanashin, Yu.P.; Sardyko, G.N.

    1980-01-01

    Cathodic processes during beryllium deposition on liquid and solid aluminium cathodes are investigated. Mixture of sodium, potassium and beryllium chloride melts served as an lectrolyte. Beryllium ion discharge at the expense of alloy formation takes place at more positive potentials than on an indifferent cathode at low current densities ( in the case of liquid aluminium cathode). Metallographic analysis and measurements of microhardness have shown, that the cathodic product includes two phases: beryllium solid solution in aluminium and metallic beryllium. It is concluded, that aluminium-beryllium alloys with high cathodic yield by current can be obtained by the electrolytic method

  7. Experimental study on hollow structural component by explosive welding

    Energy Technology Data Exchange (ETDEWEB)

    Duan, Mianjun, E-mail: dmjwl@163.com [PLA University of Science and Technology, Nanjing 210007 (China); Wei, Ling, E-mail: 386006087@qq.com [Tongda College, Nanjing University of Posts and Telecommunication, Nanjing 210007 (China); Hong, Jin [PLA University of Science and Technology, Nanjing 210007 (China); Ran, Hong [Southwestern Institute of Physics, Chengdu 610041 (China); Ma, Rui; Wang, Yaohua [PLA University of Science and Technology, Nanjing 210007 (China)

    2014-12-15

    Highlights: • This paper relates to a study on a thin double-layers hollow structural component by using an explosive welding technology. • This thin double-layer hollow structural component is an indispensable component required for certain core equipment of thermonuclear experimental reactor. • An adjusted explosive welding technology for manufacturing an inconel625 hollow structural component was developed which cannot be made by common technology. • The result shows that a metallurgical bonding was realized by the ribs and slabs of the hollow sheet. • The shearing strength of bonding interface exceeds that of the parent metal. - Abstract: A large thin-walled hollow structural component with sealed channels is required for the vacuum chamber of a thermonuclear experimental reactor, with inconel625 as its fabrication material. This hollow structural component is rarely manufactured by normal machining method, and its manufacture is also problematic in the field of explosive welding. With this in mind, we developed an adjusted explosive welding technology which involves a two-step design, setting and annealing technology. The joints were evaluated using optical microscope and scanning electron microscope, and a mechanical experiment was conducted, involving micro-hardness test, cold helium leak test and hydraulic pressure test. The results showed that a metallurgical bonding was realized by the ribs and slabs, and the shearing strength of the bonding interface exceeded that of the parent metal. Hence, the hollow structural component has a good comprehensive mechanical performance and sealing property.

  8. Experimental study on hollow structural component by explosive welding

    International Nuclear Information System (INIS)

    Duan, Mianjun; Wei, Ling; Hong, Jin; Ran, Hong; Ma, Rui; Wang, Yaohua

    2014-01-01

    Highlights: • This paper relates to a study on a thin double-layers hollow structural component by using an explosive welding technology. • This thin double-layer hollow structural component is an indispensable component required for certain core equipment of thermonuclear experimental reactor. • An adjusted explosive welding technology for manufacturing an inconel625 hollow structural component was developed which cannot be made by common technology. • The result shows that a metallurgical bonding was realized by the ribs and slabs of the hollow sheet. • The shearing strength of bonding interface exceeds that of the parent metal. - Abstract: A large thin-walled hollow structural component with sealed channels is required for the vacuum chamber of a thermonuclear experimental reactor, with inconel625 as its fabrication material. This hollow structural component is rarely manufactured by normal machining method, and its manufacture is also problematic in the field of explosive welding. With this in mind, we developed an adjusted explosive welding technology which involves a two-step design, setting and annealing technology. The joints were evaluated using optical microscope and scanning electron microscope, and a mechanical experiment was conducted, involving micro-hardness test, cold helium leak test and hydraulic pressure test. The results showed that a metallurgical bonding was realized by the ribs and slabs, and the shearing strength of the bonding interface exceeded that of the parent metal. Hence, the hollow structural component has a good comprehensive mechanical performance and sealing property

  9. Hollow metal nanostructures for enhanced plasmonics (Conference Presentation)

    Science.gov (United States)

    Genç, Aziz; Patarroyo, Javier; Sancho-Parramon, Jordi; Duchamp, Martial; Gonzalez, Edgar; Bastus, Neus G.; Houben, Lothar; Dunin-Borkowski, Rafal; Puntes, Victor F.; Arbiol, Jordi

    2016-03-01

    Complex metal nanoparticles offer a great playground for plasmonic nanoengineering, where it is possible to cover plasmon resonances from ultraviolet to near infrared by modifying the morphologies from solid nanocubes to nanoframes, multiwalled hollow nanoboxes or even nanotubes with hybrid (alternating solid and hollow) structures. We experimentally show that structural modifications, i.e. void size and final morphology, are the dominant determinants for the final plasmonic properties, while compositional variations allow us to get a fine tuning. EELS mappings of localized surface plasmon resonances (LSPRs) reveal an enhanced plasmon field inside the voids of hollow AuAg nanostructures along with a more homogeneous distributions of the plasmon fields around the nanostructures. With the present methodology and the appropriate samples we are able to compare the effects of hybridization at the nanoscale in hollow nanostructures. Boundary element method (BEM) simulations also reveal the effects of structural nanoengineering on plasmonic properties of hollow metal nanostructures. Possibility of tuning the LSPR properties of hollow metal nanostructures in a wide range of energy by modifying the void size/shell thickness is shown by BEM simulations, which reveals that void size is the dominant factor for tuning the LSPRs. As a proof of concept for enhanced plasmonic properties, we show effective label free sensing of bovine serum albumin (BSA) with some of our hollow nanostructures. In addition, the different plasmonic modes observed have also been studied and mapped in 3D.

  10. Boron nitride hollow nanospheres: Synthesis, formation mechanism and dielectric property

    Energy Technology Data Exchange (ETDEWEB)

    Zhong, B.; Tang, X.H. [School of Materials Science and Engineering, Harbin Institute of Technology at Weihai, Weihai 264209 (China); Huang, X.X., E-mail: swliza@hit.edu.cn [School of Materials Science and Engineering, Harbin Institute of Technology, Harbin 150001 (China); Xia, L. [School of Materials Science and Engineering, Harbin Institute of Technology at Weihai, Weihai 264209 (China); Zhang, X.D. [School of Materials Science and Engineering, Harbin Institute of Technology, Harbin 150001 (China); Wang, C.J. [School of Materials Science and Engineering, Harbin Institute of Technology at Weihai, Weihai 264209 (China); Wen, G.W., E-mail: g.wen@hit.edu.cn [School of Materials Science and Engineering, Harbin Institute of Technology at Weihai, Weihai 264209 (China); School of Materials Science and Engineering, Harbin Institute of Technology, Harbin 150001 (China)

    2015-04-15

    Highlights: • BN hollow nanospheres are fabricated in large scale via a new CVD method. • Morphology and structure are elucidated by complementary analytical techniques. • Formation mechanism is proposed based on experimental observations. • Dielectric properties are investigated in the X-band microwave frequencies. • BN hollow nanospheres show lower dielectric loss than regular BN powders. - Abstract: Boron nitride (BN) hollow nanospheres have been successfully fabricated by pyrolyzing vapors decomposed from ammonia borane (NH{sub 3}BH{sub 3}) at 1300 °C. The final products have been extensively characterized by X-ray diffraction, field-emission scanning electron microscopy, transmission electron microscopy, and X-ray photoelectron spectroscopy. The BN hollow nanospheres were ranging from 100 to 300 nm in diameter and around 30–100 nm in thickness. The internal structure of the products was found dependent on the reaction temperatures. A possible formation mechanism of the BN hollow nanospheres was proposed on the basis of the experimental observations. Dielectric measurements in the X-band microwave frequencies (8–12 GHz) showed that the dielectric loss of the paraffin filled by the BN hollow nanospheres was lower than that filled by regular BN powders, which indicated that the BN hollow nanospheres could be potentially used as low-density fillers for microwave radomes.

  11. Investigations Of A Pulsed Cathodic Vacuum Arc

    Science.gov (United States)

    Oates, T. W. H.; Pigott, J.; Denniss, P.; Mckenzie, D. R.; Bilek, M. M. M.

    2003-06-01

    Cathodic vacuum arcs are well established as a method for producing thin films for coatings and as a source of metal ions. Research into DC vacuum arcs has been going on for over ten years in the School of Physics at the University of Sydney. Recently a project was undertaken in the school to design and build a pulsed CVA for use in the investigation of plasma sheaths and plasma immersion ion implantation. Pulsed cathodic vacuum arcs generally have a higher current and plasma density and also provide a more stable and reproducible plasma density than their DC counterparts. Additionally it has been shown that if a high repetition frequency can be established the deposition rate of pulsed arcs is equal to or greater than that of DC arcs with a concomitant reduction in the rate of macro-particle formation. We present here results of our investigations into the building of a center-triggered pulsed cathodic vacuum arc. The design of the power supply and trigger mechanism and the geometry of the anode and cathode are examined. Observations of type I and II arc spots using a CCD camera, and cathode spot velocity dependence on arc current will be presented. The role of retrograde motion in a high current pulsed arc is discussed.

  12. Manganese Dioxide As Rechargeable Magnesium Battery Cathode

    International Nuclear Information System (INIS)

    Ling, Chen; Zhang, Ruigang

    2017-01-01

    Rechargeable magnesium battery (rMB) has received increased attention as a promising alternative to current Li-ion technology. However, the lack of appropriate cathode that provides high-energy density and good sustainability greatly hinders the development of practical rMBs. To date, the successful Mg 2+ -intercalation was only achieved in only a few cathode hosts, one of which is manganese dioxide. This review summarizes the research activity of studying MnO 2 in magnesium cells. In recent years, the cathodic performance of MnO 2 was impressively improved to the capacity of >150–200 mAh g −1 at voltage of 2.6–2.8 V with cyclability to hundreds or more cycles. In addition to reviewing electrochemical performance, we sketch a mechanistic picture to show how the fundamental understanding about MnO 2 cathode has been changed and how it paved the road to the improvement of cathode performance.

  13. Manganese Dioxide As Rechargeable Magnesium Battery Cathode

    Energy Technology Data Exchange (ETDEWEB)

    Ling, Chen, E-mail: chen.ling@toyota.com; Zhang, Ruigang [Toyota Research Institute of North America, Ann Arbor, MI (United States)

    2017-11-03

    Rechargeable magnesium battery (rMB) has received increased attention as a promising alternative to current Li-ion technology. However, the lack of appropriate cathode that provides high-energy density and good sustainability greatly hinders the development of practical rMBs. To date, the successful Mg{sup 2+}-intercalation was only achieved in only a few cathode hosts, one of which is manganese dioxide. This review summarizes the research activity of studying MnO{sub 2} in magnesium cells. In recent years, the cathodic performance of MnO{sub 2} was impressively improved to the capacity of >150–200 mAh g{sup −1} at voltage of 2.6–2.8 V with cyclability to hundreds or more cycles. In addition to reviewing electrochemical performance, we sketch a mechanistic picture to show how the fundamental understanding about MnO{sub 2} cathode has been changed and how it paved the road to the improvement of cathode performance.

  14. Investigations Of A Pulsed Cathodic Vacuum Arc

    International Nuclear Information System (INIS)

    Oates, T.W.H.; Pigott, J.; Denniss, P.; Mckenzie, D.R.; Bilek, M.M.M.

    2003-01-01

    Cathodic vacuum arcs are well established as a method for producing thin films for coatings and as a source of metal ions. Research into DC vacuum arcs has been going on for over ten years in the School of Physics at the University of Sydney. Recently a project was undertaken in the school to design and build a pulsed CVA for use in the investigation of plasma sheaths and plasma immersion ion implantation. Pulsed cathodic vacuum arcs generally have a higher current and plasma density and also provide a more stable and reproducible plasma density than their DC counterparts. Additionally it has been shown that if a high repetition frequency can be established the deposition rate of pulsed arcs is equal to or greater than that of DC arcs with a concomitant reduction in the rate of macro-particle formation. We present here results of our investigations into the building of a center-triggered pulsed cathodic vacuum arc. The design of the power supply and trigger mechanism and the geometry of the anode and cathode are examined. Observations of type I and II arc spots using a CCD camera, and cathode spot velocity dependence on arc current will be presented. The role of retrograde motion in a high current pulsed arc is discussed

  15. Broadband high-resolution multi-species CARS in gas-filled hollow-core photonic crystal fiber.

    Science.gov (United States)

    Trabold, Barbara M; Hupfer, Robert J R; Abdolvand, Amir; St J Russell, Philip

    2017-09-01

    We report the use of coherent anti-Stokes Raman spectroscopy (CARS) in gas-filled hollow-core photonic crystal fiber (HC-PCF) for trace gas detection. The long optical path-lengths yield a 60 dB increase in the signal level compared with free-space arrangements. This enables a relatively weak supercontinuum (SC) to be used as Stokes seed, along with a ns pump pulse, paving the way for broadband (>4000  cm -1 ) single-shot CARS with an unprecedented resolution of ∼100  MHz. A kagomé-style HC-PCF provides broadband guidance, and, by operating close to the pressure-tunable zero dispersion wavelength, we can ensure simultaneous phase-matching of all gas species. We demonstrate simultaneous measurement of the concentrations of multiple trace gases in a gas sample introduced into the core of the HC-PCF.

  16. The influence of cathode excavation of cathodic arc evaporator on thickness uniformity and erosion products angle distribution

    Directory of Open Access Journals (Sweden)

    D. V. Duhopel'nikov

    2014-01-01

    Full Text Available Cathodic arc evaporators are used for coating with functional films. Prolonged or buttend evaporators may be used for this purposes. In butt-end evaporator the cathode spots move continuously on the cathode work surface and evaporate cathode material. High depth excavation profile forms on the cathode work surface while the thick coating precipitation (tens or hundreds of microns. The cathode excavation profile is shaped like a “cup” with high walls for electrostatic discharge stabilization systems with axial magnetic fields. Cathode spots move on the bottom of the “cup”. It is very likely that high “cup” walls are formed as a result of lasting work time influence on the uniformity of precipitated films.In the present work the influence of excavation profile walls height on the uniformity of precipitated coating was carried out. The high profile walls are formed due to lasting work of DC vacuum arc evaporator. The cathode material used for tests was 3003 aluminum alloy. The extended substrate was placed parallel to the cathode work surface. Thickness distribution along the substrate length with the new cathode was obtained after 6 hours and after 12 hours of continuous operation.The thickness distribution of precipitated coating showed that the cathode excavation has an influence on the angular distribution of the matter escaping the cathode. It can be clearly seen from the normalized dependence coating thickness vs the distance from the substrate center. Also the angular distribution of the matter flow from the cathode depending on the cathode working time was obtained. It was shown that matter flow from the cathode differs from the LambertKnudsen law. The more the cathode excavation the more this difference.So, cathode excavation profile has an influence on the uniformity of precipitated coating and it is necessary to take in account the cathode excavation profile while coating the thick films.

  17. Sea urchin-like mesoporous carbon material grown with carbon nanotubes as a cathode catalyst support for fuel cells

    Energy Technology Data Exchange (ETDEWEB)

    Kuo, Ping-Lin; Hsu, Chun-Han; Li, Wan-Ting; Jhan, Jing-Yi; Chen, Wei-Fu [Department of Chemical Engineering, National Cheng Kung University, Tainan 70101 (China)

    2010-12-15

    A sea urchin-like carbon (UC) material with high surface area (416 m{sup 2} g{sup -1}), adequate electrical conductivity (59.6 S cm{sup -1}) and good chemical stability was prepared by growing carbon nanotubes onto mesoporous carbon hollow spheres. A uniform dispersion of Pt nanoparticles was then anchored on the UC, where the Pt nanoparticles were prepared using benzylamine as the stabilizer. For this Pt loaded carbon, cyclic voltammogram measurements showed an exceptionally high electrochemically active surface area (EAS) (114.8 m{sup 2} g{sup -1}) compared to the commonly used commercial E-TEK catalyst (65.2 m{sup 2} g{sup -1}). The durability test demonstrates that the carbon used as a support exhibited minor loss in EAS of Pt. Compared to the E-TEK (20 wt%) cathode catalyst, this Pt loaded UC catalyst has greatly enhanced catalytic activity toward the oxygen reduction reaction, less cathode flooding and considerably improved performance, resulting in an enhancement of ca. 37% in power density compared with that of E-TEK. Based on the results obtained, the UC is an excellent support for Pt nanoparticles used as cathode catalysts in proton exchange membrane fuel cells. (author)

  18. Fabrication of polypyrrole/vanadium oxide nanotube composite with enhanced electrochemical performance as cathode in rechargeable batteries

    International Nuclear Information System (INIS)

    Zhou, Xiaowei; Chen, Xu; He, Taoling; Bi, Qinsong; Sun, Li; Liu, Zhu

    2017-01-01

    Highlights: • VO_xNTs were hydrothermally prepared using C_1_2H_2_7N as soft template with scalability. • Polypyrrole/VO_xNTs with less C_1_2H_2_7N template and higher conductivity were obtained. • Polypyrrole/VO_xNTs exhibit better performance as cathode for LIBs compared to VO_xNTs. • Further modification to VO_xNTs with desired electrochemical property can be expected. - Abstract: Vanadium oxide nanotubes (VO_xNTs) with hollow as well as multi-walled features were fabricated under hydrothermal condition by soft-template method. This novel VO_xNTs can be used as cathode material for lithium ion batteries (LIBs), but displaying low specific capacity and poor cycling performance owing to the residual of a mass of soft-template (C_1_2H_2_7N) and intrinsic low conductivity of VO_x. Cation exchange technique and oxidative polymerization process of pyrrole monomers were conducted to wipe off partial soft-template without electrochemical activity within VO_xNTs and simultaneously form polypyrrole coating on VO_xNTs, respectively. The resulting polypyrrole/VO_xNTs nanocomposite delivers much improved capacity and cyclic stability. Further optimizations, such as complete elimination of organic template and enhancing the crystallinity, can make this unique nanostructure a promising cathode for LIBs.

  19. Hollow fiber membranes and methods for forming same

    Science.gov (United States)

    Bhandari, Dhaval Ajit; McCloskey, Patrick Joseph; Howson, Paul Edward; Narang, Kristi Jean; Koros, William

    2016-03-22

    The invention provides improved hollow fiber membranes having at least two layers, and methods for forming the same. The methods include co-extruding a first composition, a second composition, and a third composition to form a dual layer hollow fiber membrane. The first composition includes a glassy polymer; the second composition includes a polysiloxane; and the third composition includes a bore fluid. The dual layer hollow fiber membranes include a first layer and a second layer, the first layer being a porous layer which includes the glassy polymer of the first composition, and the second layer being a polysiloxane layer which includes the polysiloxane of the second composition.

  20. Axisymmetric Vibration of Piezo-Lemv Composite Hollow Multilayer Cylinder

    Directory of Open Access Journals (Sweden)

    E. S. Nehru

    2012-01-01

    Full Text Available Axisymmetric vibration of an infinite piezolaminated multilayer hollow cylinder made of piezoelectric layers of 6 mm class and an isotropic LEMV (Linear Elastic Materials with Voids layers is studied. The frequency equations are obtained for the traction free outer surface with continuity conditions at the interfaces. Numerical results are carried out for the inner, middle, and outer hollow piezoelectric layers bonded by LEMV (It is hypothetical material layers and the dispersion curves are compared with that of a similar 3-layer model and of 3 and 5 layer models with inner, middle, and outer hollow piezoelectric layers bonded by CFRP (Carbon fiber reinforced plastics.

  1. Recovery of uranium from seawater using amidoxime hollow fibers

    International Nuclear Information System (INIS)

    Saito, K.; Uezu, K.; Hori, T.; Furusaki, S.; Sugo, T.; Okamoto, J.

    1988-01-01

    A novel amidoxime-group-containing adsorbent of hollow-fiber form (AO-H fiber) was prepared by radiation-induced graft polymerization of acrylonitrile onto a polyethylene hollow fiber, followed by chemical conversion of the produced cyano group to an amidoxime group. Distribution of the amidoxime group was uniform throughout hollow-fiber membrane. The fixed-bed adsorption column, 30 cm in length and charged with the bundle of AO-H fibers, was found to adsorb uranium from natural seawater at a sufficiently high rate: 0.66 mg uranium per g of adsorbent in 25 days

  2. Development of hollow electron beams for proton and ion collimation

    CERN Document Server

    Stancari, G; Kuznetsov, G; Shiltsev, V; Still, D A; Valishev, A; Vorobiev, L G; Assmann, R; Kabantsev, A

    2012-01-01

    Magnetically confined hollow electron beams for controlled halo removal in high-energy colliders such as the Tevatron or the LHC may extend traditional collimation systems beyond the intensity limits imposed by tolerable material damage. They may also improve collimation performance by suppressing loss spikes due to beam jitter and by increasing capture efficiency. A hollow electron gun was designed and built. Its performance and stability were measured at the Fermilab test stand. The gun will be installed in one of the existing Tevatron electron lenses for preliminary tests of the hollow-beam collimator concept, addressing critical issues such as alignment and instabilities of the overlapping proton and electron beams.

  3. Development of hollow electron beams for proton and ion collimation

    CERN Document Server

    Stancari, G.; Kuznetsov, G.; Shiltsev, V.; Still, D.A.; Valishev, A.; Vorobiev, L.G.; Assmann, R.; Kabantsev, A.

    2010-01-01

    Magnetically confined hollow electron beams for controlled halo removal in high-energy colliders such as the Tevatron or the LHC may extend traditional collimation systems beyond the intensity limits imposed by tolerable material damage. They may also improve collimation performance by suppressing loss spikes due to beam jitter and by increasing capture efficiency. A hollow electron gun was designed and built. Its performance and stability were measured at the Fermilab test stand. The gun will be installed in one of the existing Tevatron electron lenses for preliminary tests of the hollow-beam collimator concept, addressing critical issues such as alignment and instabilities of the overlapping proton and electron beams

  4. Generation and propagation characteristics of a localized hollow beam

    Science.gov (United States)

    Xia, Meng; Wang, Zhizhang; Yin, Yaling; Zhou, Qi; Xia, Yong; Yin, Jianping

    2018-05-01

    A succinct experimental scheme is demonstrated to generate a localized hollow beam by using a π-phase binary bitmap and a convergent thin lens. The experimental results show that the aspect ratio of the dark-spot size of the hollow beam can be effectively controlled by the focal length of the lens. The measured beam profiles in free space also agree with the theoretical modeling. The studies hold great promise that such a hollow beam can be used to cool trapped atoms (or molecules) by Sisyphus cooling and to achieve an optically-trapped Bose–Einstein condensate by optical-potential evaporative cooling.

  5. Two-piece hollow bulb obturator

    Directory of Open Access Journals (Sweden)

    Subramaniam Elangovan

    2011-01-01

    Full Text Available There are various types of obturator fabrication achievable by prosthodontist. Maxillectomy, which is a term used by head and neck surgeons and prosthodontists to describe the partial or total removal of the maxilla in patients suffering from benign or malignant neoplasms is a defect for which to provide an effective obturator is a difficult task for the maxillofacial prosthodontist. Multidisciplinary treatment planning is essential to achieve adequate retention and function for the prosthesis. Speech is often unintelligible as a result of the marked defects in articulation and nasal resonance. This paper describes how to achieve the goal for esthetics and phonetics and also describes the fabrication of a hollow obturator by two piece method, which is simple and maybe used as definitive obturator for maximum comfort of the patient.

  6. Oxide cathodes produced by plasma deposition

    International Nuclear Information System (INIS)

    Scheitrum, G.; Caryotakis, G.; Pi, T.; Umstattd, R.; Brown, I.; Montiero, O.

    1997-01-01

    These are two distinct applications for high-current-density, long-life thermionic cathodes. The first application is as a substitute for explosive emission cathodes used in high-power microwave (HPM) devices being developed for Air Force programs. The second application is in SLAC's X-band klystrons for the Next Linear Collider (NLC). SLAC, UCD, and LBL are developing a plasma deposition process that eliminates the problems with binders, carbonate reduction, peeling, and porosity. The emission layer is deposited using plasma deposition of metallic barium in vacuum with an oxygen background gas. An applied bias voltage drives the oxide plasma into the nickel surface. Since the oxide is deposited directly, it does not have problems with poisoning from a hydrocarbon binder. The density of the oxide layer is increased from the 40--50% for standard oxide cathodes to nearly 100% for plasma deposition

  7. Synchrotron Investigations of SOFC Cathode Degradation

    Energy Technology Data Exchange (ETDEWEB)

    Idzerda, Yves

    2013-09-30

    The atomic variations occurring in cathode/electrolyte interface regions of La{sub 1-x}Sr{sub x}Co{sub y}Fe{sub 1-y}O{sub 3-δ} (LSCF) cathodes and other SOFC related materials have been investigated and characterized using soft X-ray Absorption Spectroscopy (XAS) and diffuse soft X-ray Resonant Scattering (XRS). X-ray Absorption Spectroscopy in the soft X-ray region (soft XAS) is shown to be a sensitive technique to quantify the disruption that occurs and can be used to suggest a concrete mechanism for the degradation. For LSC, LSF, and LSCF films, a significant degradation mechanism is shown to be Sr out-diffusion. By using the XAS spectra of hexavalent Cr in SrCrO4 and trivalent Cr in Cr2O3, the driving factor for Sr segregation was identified to be the oxygen vacancy concentration at the anode and cathode side of of symmetric LSCF/GDC/LSCF heterostructures. This is direct evidence of vacancy induced cation diffusion and is shown to be a significant indicator of cathode/electrolyte interfacial degradation. X-ray absorption spectroscopy is used to identify the occupation of the A-sites and B-sites for LSC, LSF, and LSCF cathodes doped with other transition metals, including doping induced migration of Sr to the anti-site for Sr, a significant cathode degradation indicator. By using spatially resolved valence mapping of Co, a complete picture of the surface electrochemistry can be determined. This is especially important in identifying degradation phenomena where the degradation is spatially localized to the extremities of the electrochemistry and not the average. For samples that have electrochemical parameters that are measured to be spatially uniform, the Co valence modifications were correlated to the effects of current density, overpotential, and humidity.

  8. High-power circulator test results at 350 and 700 MHz

    International Nuclear Information System (INIS)

    Roybal, W.; Bradley, J.T.; Rees, D.E.

    2000-01-01

    The high-power RF systems for the Accelerator Production of Tritium (APT) program require high-power circulators at 350 MHz and 700 MHz to protect 1 MW Continuous Wave (CW) klystrons from reflected power. The 350 MHz circulator is based on the CERN, EXF, and APS designs and has performed very well. The 700 MHz circulator is a new design. Prototype 700 MHz circulators have been high-power tested at Los Alamos National Laboratory (LANL). The first of these circulators has satisfied performance requirements. The circulator requirements, results from the testing, and lessons learned from this development are presented and discussed

  9. Two-dimensional 220 MHz Fourier transform EPR imaging

    International Nuclear Information System (INIS)

    Placidi, Giuseppe; Brivati, John A.; Alecci, Marcello; Testa, Luca; Sotgiu, Antonello

    1998-01-01

    In the last decade radiofrequency continuous-wave EPR spectrometers have been developed to detect and localize free radicals in vivo. Only recently, pulsed radiofrequency EPR spectrometers have been described for imaging applications with small samples. In the present work, we show the first two-dimensional image obtained at 220 MHz on a large phantom (40 ml) that simulates typical conditions of in vivo EPR imaging. This pulsed EPR apparatus has the potential to make the time required for three-dimensional imaging compatible with the biological half-life of normally used paramagnetic probes. (author)

  10. Operation of a 473 MHz four-rod cavity RFQ

    International Nuclear Information System (INIS)

    Kazimi, R.; Huson, F.R.; Mackay, W.W.; Meitzler, C.R.

    1992-01-01

    We have constructed a new type of four-rod Radio Frequency Quadrupole to operate at 473 MHz. Four-rod structures have not previously been built for such a high frequency. The RFQ is designed to accelerate 10 mA of H - ions from 30 keV to 0.5 MeV. The rf measurements and beam test of the RFQ have been performed successfully. Here we present operational results of the RFQ system including measurements of the beam current, the required rf power, energy, energy spread, and emittance. (Author) 8 refs., 6 figs., 2 tabs

  11. LAMPF 201.25-MHz linac field distribution

    International Nuclear Information System (INIS)

    Jameson, R.A.; Halbig, J.K.

    1978-01-01

    Returning of the 201.25-MHz accelerator structure field distributions after the 1975 shutdown is described, and final data are given for use in beam dynamics studies. Several improvements made in procedures included a different method for stopband closure check and a positive method for postcoupler clamping. To obtain accurate results for the first tank a rigorous data reduction technique that included the removal of a ''signature'' due to the bead-pull string itself was used. Other special studies are reported, including the effects of vacuum, bead size, slug tuners, and a bead-pull method for measuring the cavity quality factor Q

  12. BNL 56 MHz HOM Damper Prototype Fabrication at JLab

    Energy Technology Data Exchange (ETDEWEB)

    Huque, Naeem A. [Jefferson Lab., Newport News, VA (United States); Daly, Edward F. [Jefferson Lab., Newport News, VA (United States); Clemens, William A. [Jefferson Lab., Newport News, VA (United States); McIntyre, Gary T. [Brookhaven National Lab. (BNL), Upton, NY (United States); Wu, Qiong [Brookhaven National Lab. (BNL), Upton, NY (United States); Seberg, Scott [Brookhaven National Lab. (BNL), Upton, NY (United States); Bellavia, Steve [Brookhaven National Lab. (BNL), Upton, NY (United States)

    2015-09-01

    A prototype Higher-Order Mode (HOM) Damper was fabricated at JLab for the Relativistic Heavy-Ion Collider's (RHIC) 56 MHz cavity at Brookhaven National Laboratory (BNL). Primarily constructed from high RRR Niobium and Sapphire, the coaxial damper presented significant challenges in electron-beam welding (EBW), brazing and machining via acid etching. The results of the prototype operation brought about changes in the damper design, due to overheating braze alloys and possible multi-pacting. Five production HOM dampers are currently being fabricated at JLab. This paper outlines the challenges faced in the fabrication process, and the solutions put in place.

  13. Effects of 415 MHz frequency on human lymphocyte genome

    International Nuclear Information System (INIS)

    Garaj-Vrhovac, V.; Fucic, A.; Kubelka, D.; Vojvodic, S.

    1996-01-01

    The continuously increasing use of artificial sources of electromagnetic radiation in industry and medicine has been accompanied in everyday life with telecommunication systems which is followed with great interest in possible hazardous effects of this type of radiation. The interesting applications of mobile telecommunications and the use of cellular phones are of topic interest. Numerous cytogenetic investigations are focused on the effects of microwave radiation from mobile communications frequency of 450 and 950 MHz on isolated cells in vitro. The aim of this work was to investigate the effects of microwaves from mobile telephone frequencies on human peripheral blood lymphocytes cultured in vitro. (author)

  14. Measure of enzymatic activity coincident with 2450 MHz microwave exposure

    Energy Technology Data Exchange (ETDEWEB)

    Ward, T R; Allis, J W; Elder, J A

    1975-09-01

    Enzyme preparations were exposed to microwave radiation at 2450 MHz and enzymatic activity was simultaneously monitored spectrophotometrically with a crossed-beam exposure detection system. Enzymes studied were glucose 6-phosphate dehydrogenase from human red blood cells and yeast, adenylate kinase from rat liver mitochondria and rabbit muscle, and rat liver microsomal NADPH cytochrome c reductase. No difference was found between the specific activity at 25/sup 0/C of unirradiated controls and enzyme preparations irradiated at an absorbed dose rate of 42 W/kg.

  15. Controls and interlocks for a prototype 1MHz beam chopper

    International Nuclear Information System (INIS)

    Waters, G.; Bishop, D.; Barnes, M.J.; Wait, G.D.

    1991-05-01

    A prototype 1 MHz beam chopper for the proposed KAON Factory at TRIUMF has been constructed. The chopper is an electric field device, driven by a tetrode based pulser, for deflecting a charged particle beam. Associated with the tetrode used in the prototype design are high voltage power supplies for the electrodes. We use an FET based grid pulser and a sequencer capable of accurate digital control of pulse timing to 0.4 ns. A safety interlock and control system using a programmable controller with fibre optic links has been built. This has given us the versatility required in a prototype system. (Author) 4 refs., 5 figs

  16. MHz gravitational waves from short-term anisotropic inflation

    International Nuclear Information System (INIS)

    Ito, Asuka; Soda, Jiro

    2016-01-01

    We reveal the universality of short-term anisotropic inflation. As a demonstration, we study inflation with an exponential type gauge kinetic function which is ubiquitous in models obtained by dimensional reduction from higher dimensional fundamental theory. It turns out that an anisotropic inflation universally takes place in the later stage of conventional inflation. Remarkably, we find that primordial gravitational waves with a peak amplitude around 10 −26 ∼10 −27 are copiously produced in high-frequency bands 10 MHz∼100 MHz. If we could detect such gravitational waves in future, we would be able to probe higher dimensional fundamental theory.

  17. Brightness distribution data on 2918 radio sources at 365 MHz

    International Nuclear Information System (INIS)

    Cotton, W.D.; Owen, F.N.; Ghigo, F.D.

    1975-01-01

    This paper is the second in a series describing the results of a program attempting to fit models of the brightness distribution to radio sources observed at 365 MHz with the Bandwidth Synthesis Interferometer (BSI) operated by the University of Texas Radio Astronomy Observatory. Results for a further 2918 radio sources are given. An unresolved model and three symmetric extended models with angular sizes in the range 10--70 arcsec were attempted for each radio source. In addition, for 348 sources for which other observations of brightness distribution are published, the reference to the observations and a brief description are included

  18. Ferroelectric Cathodes in Transverse Magnetic Fields

    International Nuclear Information System (INIS)

    Alexander Dunaevsky; Yevgeny Raitses; Nathaniel J. Fisch

    2002-01-01

    Experimental investigations of a planar ferroelectric cathode in a transverse magnetic field up to 3 kGs are presented. It is shown that the transverse magnetic field affects differently the operation of ferroelectric plasma cathodes in ''bright'' and ''dark'' modes in vacuum. In the ''bright'' mode, when the surface plasma is formed, the application of the transverse magnetic field leads to an increase of the surface plasma density. In the ''dark'' mode, the magnetic field inhibits the development of electron avalanches along the surface, as it does similarly in other kinds of surface discharges in the pre-breakdown mode

  19. Cathode architectures for alkali metal / oxygen batteries

    Science.gov (United States)

    Visco, Steven J; Nimon, Vitaliy; De Jonghe, Lutgard C; Volfkovich, Yury; Bograchev, Daniil

    2015-01-13

    Electrochemical energy storage devices, such as alkali metal-oxygen battery cells (e.g., non-aqueous lithium-air cells), have a cathode architecture with a porous structure and pore composition that is tailored to improve cell performance, especially as it pertains to one or more of the discharge/charge rate, cycle life, and delivered ampere-hour capacity. A porous cathode architecture having a pore volume that is derived from pores of varying radii wherein the pore size distribution is tailored as a function of the architecture thickness is one way to achieve one or more of the aforementioned cell performance improvements.

  20. DARHT 2 kA Cathode Development

    Energy Technology Data Exchange (ETDEWEB)

    Henestroza, E.; Houck, T.; Kwan, J.W.; Leitner, M.; Miram, G.; Prichard, B.; Roy, P.K.; Waldron, W.; Westenskow, G.; Yu, S.; Bieniosek, F.M.

    2009-03-09

    In the campaign to achieve 2 kA of electron beam current, we have made several changes to the DARHT-II injector during 2006-2007. These changes resulted in a significant increase in the beam current, achieving the 2 kA milestone. Until recently (before 2007), the maximum beam current that was produced from the 6.5-inch diameter (612M) cathode was about 1300 A when the cathode was operating at a maximum temperature of 1140 C. At this temperature level, the heat loss was dominated by radiation which is proportional to temperature to the fourth power. The maximum operating temperature was limited by the damage threshold of the potted filament and the capacity of the filament heater power supply, as well as the shortening of the cathode life time. There were also signs of overheating at other components in the cathode assembly. Thus it was clear that our approach to increase beam current could not be simply trying to run at a higher temperature and the preferred way was to operate with a cathode that has a lower work function. The dispenser cathode initially used was the type 612M made by SpectraMat. According to the manufacturer's bulletin, this cathode should be able to produce more than 10 A/cm{sup 2} of current density (corresponding to 2 kA of total beam current) at our operating conditions. Instead the measured emission (space charge limited) was 6 A/cm{sup 2}. The result was similar even after we had revised the activation and handling procedures to adhere more closely to the recommend steps (taking longer time and nonstop to do the out-gassing). Vacuum was a major concern in considering the cathode's performance. Although the vacuum gauges at the injector vessel indicated 10{sup -8} Torr, the actual vacuum condition near the cathode in the central region of the vessel, where there might be significant out-gassing from the heater region, was never determined. Poor vacuum at the surface of the cathode degraded the emission (by raising the work function

  1. DARHT 2 kA Cathode Development

    International Nuclear Information System (INIS)

    Henestroza, E.; Houck, T.; Kwan, J.W.; Leitner, M.; Miram, G.; Prichard, B.; Roy, P.K.; Waldron, W.; Westenskow, G.; Yu, S.; Bieniosek, F.M.

    2009-01-01

    In the campaign to achieve 2 kA of electron beam current, we have made several changes to the DARHT-II injector during 2006-2007. These changes resulted in a significant increase in the beam current, achieving the 2 kA milestone. Until recently (before 2007), the maximum beam current that was produced from the 6.5-inch diameter (612M) cathode was about 1300 A when the cathode was operating at a maximum temperature of 1140 C. At this temperature level, the heat loss was dominated by radiation which is proportional to temperature to the fourth power. The maximum operating temperature was limited by the damage threshold of the potted filament and the capacity of the filament heater power supply, as well as the shortening of the cathode life time. There were also signs of overheating at other components in the cathode assembly. Thus it was clear that our approach to increase beam current could not be simply trying to run at a higher temperature and the preferred way was to operate with a cathode that has a lower work function. The dispenser cathode initially used was the type 612M made by SpectraMat. According to the manufacturer's bulletin, this cathode should be able to produce more than 10 A/cm 2 of current density (corresponding to 2 kA of total beam current) at our operating conditions. Instead the measured emission (space charge limited) was 6 A/cm 2 . The result was similar even after we had revised the activation and handling procedures to adhere more closely to the recommend steps (taking longer time and nonstop to do the out-gassing). Vacuum was a major concern in considering the cathode's performance. Although the vacuum gauges at the injector vessel indicated 10 -8 Torr, the actual vacuum condition near the cathode in the central region of the vessel, where there might be significant out-gassing from the heater region, was never determined. Poor vacuum at the surface of the cathode degraded the emission (by raising the work function value). We reexamined

  2. Cathode characterization system: preliminary results with (Ba,Sr,Ca) O coated cathodes

    International Nuclear Information System (INIS)

    Nono, M.C.A.; Goncalves, J.A.N.; Barroso, J.J.; Dallaqua, R.S.; Spassovsky, I.

    1993-01-01

    The performance of a cathode characterization system for studying the emission parameters of thermal electron emitters is reported. The system consists of vacuum chamber, power supplies and equipment for measuring and control. Measurements have been taken of the emission current as function of cathode temperature and anode voltage. Several (Ba, Sr) O coated cathodes were tested and the results have shown good agreement with Child's and Richardson's laws. The experimental work function is between 1.0 and 2.0 e V. All emission parameters measured are consistent with international literature data. (author)

  3. A Novel Cathode Material for Cathodic Dehalogenation of 1,1-Dibromo Cyclopropane Derivatives.

    Science.gov (United States)

    Gütz, Christoph; Selt, Maximilian; Bänziger, Markus; Bucher, Christoph; Römelt, Christina; Hecken, Nadine; Gallou, Fabrice; Galvão, Tomás R; Waldvogel, Siegfried R

    2015-09-28

    Leaded bronze turned out to be an excellent cathode material for the dehalogenation reaction of cyclopropanes without affecting the strained molecular entity. With this particular alloy, beneficial properties of lead cathodes are conserved, whereas the corrosion of cathode is efficiently suppressed. The solvent in the electrolyte determines whether a complete debromination reaction is achieved or if the process can be selectively stopped at the monobromo cyclopropane intermediate. The electroorganic conversion tolerates a variety of functional groups and can be conducted at rather complex substrates like cyclosporine A. This approach allows the sustainable preparation of cyclopropane derivatives. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  4. Li- and Mn-Rich Cathode Materials: Challenges to Commercialization

    Energy Technology Data Exchange (ETDEWEB)

    Zheng, Jianming [Energy and Environmental Directorate, Pacific Northwest National Laboratory, 902 Battelle Boulevard Richland WA 99354 USA; Myeong, Seungjun [School of Energy and Chemical Engineering, Green Energy Materials Development Center, Ulsan National Institute of Science and Technology (UNIST), Korea 689-798; Cho, Woongrae [School of Energy and Chemical Engineering, Green Energy Materials Development Center, Ulsan National Institute of Science and Technology (UNIST), Korea 689-798; Yan, Pengfei [Environmental Molecular Sciences Laboratory, Pacific Northwest National Laboratory, 902 Battelle Boulevard Richland WA 99354 USA; Xiao, Jie [Energy and Environmental Directorate, Pacific Northwest National Laboratory, 902 Battelle Boulevard Richland WA 99354 USA; Wang, Chongmin [Environmental Molecular Sciences Laboratory, Pacific Northwest National Laboratory, 902 Battelle Boulevard Richland WA 99354 USA; Cho, Jaephil [School of Energy and Chemical Engineering, Green Energy Materials Development Center, Ulsan National Institute of Science and Technology (UNIST), Korea 689-798; Zhang, Ji-Guang [Energy and Environmental Directorate, Pacific Northwest National Laboratory, 902 Battelle Boulevard Richland WA 99354 USA

    2016-12-14

    The lithium- and manganese-rich (LMR) layered structure cathode exhibit one of the highest specific energy (~900 Wh kg-1) among all the cathode materials. However, the practical applications of LMR cathodes are still hindered by several significant challenges including voltage fade, large initial capacity loss, poor rate capability and limited cycle life. Herein, we review the recent progresses and understandings on the application of LMR cathode materials from practical point of view. Several key parameters of LMR cathodes that affect the LMR/graphite full cell operation are systematically analysed. These factors include the first cycle capacity loss, voltage fade, powder tap density, electrode density of LMR based cathode etc. New approaches to minimize the detrimental effect of these factors are highlighted in this work. We also provided the perspectives for the future research on LMR cathode materials, focusing on addressing the fundamental problems of LMR cathodes while always keeping practical considerations in mind.

  5. Impressed current cathodic protection of deep water structures

    Digital Repository Service at National Institute of Oceanography (India)

    Venkatesan, R.

    that the cathodic protection design approaches for shallow water may not be adequate for deeper water. This paper discusses on environmental factors encountered in deep water and their effect on cathodic protection behaviour of steel. Further, current CP design...

  6. Long Life Cold Cathodes for Hall effect Thrusters, Phase I

    Data.gov (United States)

    National Aeronautics and Space Administration — An electron source incorporating long life, high current density cold cathodes inside a microchannel plate for use with ion thrusters is proposed. Cathode lifetime...

  7. Preparation of hollow microspheres of Ce{sup 3+} doped NiCo ferrite with high microwave absorbing performance

    Energy Technology Data Exchange (ETDEWEB)

    Duan, Hong-zhen, E-mail: duanhz2000@163.com; Zhou, Fang-ling; Cheng, Xia; Chen, Guo-hong; Li, Qiao-ling

    2017-02-15

    Hollow microspheres of Ce{sup 3+} doped NiCo-ferrites were synthesized by template-based-deposition and surface reaction method with carbon sphere as the template. The phase structure, morphology, magnetic properties and wave absorbing properties of the sample were characterized by X-ray powder diffraction(XRD), Scanning electronic microscopy(SEM), Vibration sample magnetometer (VSM) and a network vector analyzer (NVA), respectively. The results indicated that the particle size of the carbon sphere sample prepared by hydrothermal method was about 0.5 µm and the particle size of the Ni{sub 0.5}Co{sub 0.5}Fe{sub 2}O{sub 4} sample prepared by template-based method was about 300 nm. The influence of the amount of rare earth element on the magnetic and absorbing properties of sample was studied. The saturation magnetization and coercivity decreased gradually with the increase of the content of Ce. When the content of Ce was 0.02, the maximal saturation magnetization value and coercivity was 75.72 emu• g{sup −1} and 789.88 Oe, respectively. The associated ferrite hollow spheres have good absorbing performance, and the return loss value was −18.8 dB at 5500 MHz. - Highlights: • Hollow microspheres of Ce{sup 3+} doped NiCo-ferrites were synthesized by template-based-deposition and surface reaction method. • The influence of rare earth Ce{sup 3+} on the magnetic and absorbing properties of sample was studied. • When the content of Ce was 0.02, the maximal saturation magnetization value and coercivity was 75.72 emu• g{sup −1} and 789.88 Oe, respectively.

  8. Frequency stabilization of a 2.05 μm laser using hollow-core fiber CO2 frequency reference cell

    Science.gov (United States)

    Meras, Patrick; Poberezhskiy, Ilya Y.; Chang, Daniel H.; Spiers, Gary D.

    2010-04-01

    We have designed and built a hollow-core fiber frequency reference cell, filled it with CO2, and used it to demonstrate frequency stabilization of a 2.05 μm Tm:Ho:YLF laser using frequency modulation (FM) spectroscopy technique. The frequency reference cell is housed in a compact and robust hermetic package that contains a several meter long hollow-core photonic crystal fiber optically coupled to index-guiding fibers with a fusion splice on one end and a mechanical splice on the other end. The package has connectorized fiber pigtails and a valve used to evacuate, refill it, or adjust the gas pressure. We have demonstrated laser frequency standard deviation decreasing from >450MHz (free-running) to laser wavelength is of particular interest for spectroscopic instruments due to the presence of many CO2 and H20 absorption lines in its vicinity. To our knowledge, this is the first reported demonstration of laser frequency stabilization at this wavelength using a hollow-core fiber reference cell. This approach enables all-fiber implementation of the optical portion of laser frequency stabilization system, thus making it dramatically more lightweight, compact, and robust than the traditional free-space version that utilizes glass or metal gas cells. It can also provide much longer interaction length of light with gas and does not require any alignment. The demonstrated frequency reference cell is particularly attractive for use in aircraft and space coherent lidar instruments for measuring atmospheric CO2 profile.

  9. Polyazole hollow fiber membranes for direct contact membrane distillation

    KAUST Repository

    Maab, Husnul; Alsaadi, Ahmad Salem; Francis, Lijo; Livazovic, Sara; Ghaffour, NorEddine; Amy, Gary L.; Nunes, Suzana Pereira

    2013-01-01

    Porous hollow fiber membranes were fabricated from fluorinated polyoxadiazole and polytriazole by a dry-wet spinning method for application in desalination of Red Sea water by direct contact membrane distillation (DCMD). The data were compared with commercially available hollow fiber MD membranes prepared from poly(vinylidene fluoride). The membranes were characterized by electron microscopy, liquid entry pressure (LEP), and pore diameter measurements. Finally, the hollow fiber membranes were tested for DCMD. Salt selectivity as high as 99.95% and water fluxes as high as 35 and 41 L m -2 h-1 were demonstrated, respectively, for polyoxadiazole and polytriazole hollow fiber membranes, operating at 80 C feed temperature and 20 C permeate. © 2013 American Chemical Society.

  10. Hollow porous-wall glass microspheres for hydrogen storage

    Science.gov (United States)

    Heung, Leung K.; Schumacher, Ray F.; Wicks, George G.

    2010-02-23

    A porous wall hollow glass microsphere is provided having a diameter range of between 1 to 200 microns, a density of between 1.0 to 2.0 gm/cc, a porous-wall structure having wall openings defining an average pore size of between 10 to 1000 angstroms, and which contains therein a hydrogen storage material. The porous-wall structure facilitates the introduction of a hydrogen storage material into the interior of the porous wall hollow glass microsphere. In this manner, the resulting hollow glass microsphere can provide a membrane for the selective transport of hydrogen through the porous walls of the microsphere, the small pore size preventing gaseous or liquid contaminants from entering the interior of the hollow glass microsphere.

  11. Fundamental investigation on the impact strength of hollow fan blades

    Energy Technology Data Exchange (ETDEWEB)

    Ikeda, T; Miyachi, T; Sofue, Y

    1985-01-01

    Models of hollow fan blades were made and tested to prove that their strength is sufficient for use in real engines. The hollow blades were fabricated by diffusion bonding of two titanium alloy (6Al-4V-Ti) plates, one of which had three spanwise stiffners and the other being flat plate. The model as a nontwisted tapered blade. Impact tests were carried out on the hollow fan blade models in which the ingestion of a 1.5 pounds bird was simulated. Solid blades with the same external form were also tested by similar methods for comparison. The results of these tests show that properly designed hollow blades have sufficient stiffness and strength for use as fan blades in the turbo-fan engine.

  12. Coprecipitation-assisted hydrothermal synthesis of PLZT hollow nanospheres

    International Nuclear Information System (INIS)

    Zhu, Renqiang; Zhu, Kongjun; Qiu, Jinhao; Bai, Lin; Ji, Hongli

    2010-01-01

    Lanthanum-modified lead zirconate titanate Pb 1-x La x (Zr 1-y Ti y )O 3 (PLZT) hollow nanospheres have been successfully prepared via a template-free hydrothermal method using the well-mixed coprecipitated precursors and the KOH mineralizer. The structure, composition, and morphology of the PLZT hollow nanospheres were characterized by XRD (X-ray diffraction), ICP (inductive coupled plasma emission spectrometer), FTIR (Fourier transform infrared spectra), TG/DTA (thermogravimetric analysis and differential thermal analysis), TEM (transmission electron microscopy) and SEAD (selected area diffraction). The results show that the composition and the morphology control of the PLZT products are determined by the KOH concentration. The PLZT hollow nanospheres with uniform size of about 4 nm were synthesized in the presence of 5 M KOH. The crystalline nanoparticles can be prepared at dilute KOH, in contrast to the amorphous powders prepared at concentrated KOH. Formation mechanisms of the PLZT hollow nanospheres are also discussed.

  13. Spray Modeling for Outwardly-Opening Hollow-Cone Injector

    KAUST Repository

    Sim, Jaeheon; Badra, Jihad; Elwardani, Ahmed Elsaid; Im, Hong G.

    2016-01-01

    linear instability sheet atomization (LISA) model was originally developed for pressure swirl hollow-cone injectors with moderate spray angle and toroidal ligament breakups. Therefore, it is not appropriate for the outwardly-opening injectors having wide

  14. Polyazole hollow fiber membranes for direct contact membrane distillation

    KAUST Repository

    Maab, Husnul

    2013-08-07

    Porous hollow fiber membranes were fabricated from fluorinated polyoxadiazole and polytriazole by a dry-wet spinning method for application in desalination of Red Sea water by direct contact membrane distillation (DCMD). The data were compared with commercially available hollow fiber MD membranes prepared from poly(vinylidene fluoride). The membranes were characterized by electron microscopy, liquid entry pressure (LEP), and pore diameter measurements. Finally, the hollow fiber membranes were tested for DCMD. Salt selectivity as high as 99.95% and water fluxes as high as 35 and 41 L m -2 h-1 were demonstrated, respectively, for polyoxadiazole and polytriazole hollow fiber membranes, operating at 80 C feed temperature and 20 C permeate. © 2013 American Chemical Society.

  15. Investigation of concrete mixtures incorporating hollow plastic microspheres.

    Science.gov (United States)

    1981-01-01

    This study investigated the potential of hollow plastic microspheres, HPM, for providing non-air-entrained portland cement concrete resistance to damage from cycles of freezing and thawing. In the study, a mixture with an air-entraining agent (vinsol...

  16. Block copolymer/homopolymer dual-layer hollow fiber membranes

    KAUST Repository

    Hilke, Roland; Neelakanda, Pradeep; Behzad, Ali Reza; Nunes, Suzana Pereira; Peinemann, Klaus-Viktor

    2014-01-01

    We manufactured the first time block copolymer dual-layer hollow fiber membranes and dual layer flat sheet membranes manufactured by double solution casting and phase inversion in water. The support porous layer was based on polystyrene

  17. LOW TEMPERATURE CATHODE SUPPORTED ELECTROLYTES

    Energy Technology Data Exchange (ETDEWEB)

    Harlan U. Anderson

    2000-03-31

    . However, they have the potential of being useful as an interface on the anode side of the electrolyte. NexTech has focused much of its effort during the past few months on establishing tape casting methods for porous LSM substrates. This work, performed under a separate DOE-funded program, involved tape casting formulations comprising LSM powders with bi-modal particle size distributions and fugitive pore forming additives. Sintered LSM substrates with porosities in the 30 to 40 vol% range, and pore sizes of 10 {approx} 20 microns have been prepared. In addition, tape casting formulations involving composite mixtures of LSM and Sm-doped ceria (SDC) have been evaluated. The LSM/SDC cathode substrates are expected to provide better performance at low temperatures. Characterization of these materials is currently underway.

  18. LOW TEMPERATURE CATHODE SUPPORTED ELECTROLYTES

    Energy Technology Data Exchange (ETDEWEB)

    Harlan U. Anderson; Wayne Huebner; Igor Kosacki

    2001-09-30

    This project has three main goals: Thin Films Studies, Preparation of Graded Porous Substrates and Basic Electrical Characterization and testing of Planar Single Cells. In this portion of study we have focused on producing YSZ films on porous LSM substrates. When using the polymer precursor there are a number of obstacles to overcome in order to form dense electrolyte layers on porous substrates (cathode or anode). Probably the most difficult problems are: (1) Extreme penetration of the polymer into the substrate must be prevented. (2) Shrinkage cracking must be avoided. (3) Film thickness in the 1 to 5{micro}m range must be achieved. We have demonstrated that cracking due to shrinkage involved during the elimination of solvents and organic matter and densification of the remaining oxide is not a problem as long as the resulting oxide film is < {approx} 0.15 {micro}m in thickness. We have also shown that we can make thicker films by making multiple depositions if the substrate is smooth (roughness {le} 0.1 {micro}m) and contains no surface pores > 0.2 {micro}m. The penetration of the polymer into the porous substrate can be minimized by increasing the viscosity of the polymer and reducing the largest pore at the surface of the substrate to {le} 0.2 {micro}m. We have shown that this can be done, but we have also shown that it is difficult to make dense films that are defect free with areas > 1 cm{sup 2}. This is because of the roughness of the substrate and the difficulty in making a substrate which does not have surface voids > 0.2 {micro}m. Thus the process works well for dense, smooth substrates for films < 1 {micro}m thick, but is difficult to apply to rough, porous surfaces and to make film thickness > 1 {micro}m. As a result of these problems, we have been addressing the issue of how to make dense films in the thickness range of 1 to 5 {micro}m on sintered porous substrates without introducing cracks and holes due to shrinkage and surface voids? These

  19. 47 CFR 90.259 - Assignment and use of frequencies in the bands 216-220 MHz and 1427-1432 MHz.

    Science.gov (United States)

    2010-10-01

    ... MHz band are secondary to the Wireless Medical Telemetry Service except in the locations specified in... operations are secondary to the Wireless Medical Telemetry Service in the 1429-1431.5 MHz band. (3) All... 47 Telecommunication 5 2010-10-01 2010-10-01 false Assignment and use of frequencies in the bands...

  20. 47 CFR 101.82 - Reimbursement and relocation expenses in the 2110-2150 MHz and 2160-2200 MHz bands.

    Science.gov (United States)

    2010-10-01

    ... 47 Telecommunication 5 2010-10-01 2010-10-01 false Reimbursement and relocation expenses in the... License Transfers, Modifications, Conditions and Forfeitures § 101.82 Reimbursement and relocation expenses in the 2110-2150 MHz and 2160-2200 MHz bands. (a) Reimbursement and relocation expenses for the...

  1. 3D hollow nanostructures as building blocks for multifunctional plasmonics

    KAUST Repository

    De Angelis, Francesco De; Malerba, Mario; Patrini, Maddalena; Miele, Ermanno; Das, Gobind; Toma, Andrea; Proietti Zaccaria, Remo; Di Fabrizio, Enzo M.

    2013-01-01

    We present an advanced and robust technology to realize 3D hollow plasmonic nanostructures which are tunable in size, shape, and layout. The presented architectures offer new and unconventional properties such as the realization of 3D plasmonic hollow nanocavities with high electric field confinement and enhancement, finely structured extinction profiles, and broad band optical absorption. The 3D nature of the devices can overcome intrinsic difficulties related to conventional architectures in a wide range of multidisciplinary applications. © 2013 American Chemical Society.

  2. 3D hollow nanostructures as building blocks for multifunctional plasmonics

    KAUST Repository

    De Angelis, Francesco De

    2013-08-14

    We present an advanced and robust technology to realize 3D hollow plasmonic nanostructures which are tunable in size, shape, and layout. The presented architectures offer new and unconventional properties such as the realization of 3D plasmonic hollow nanocavities with high electric field confinement and enhancement, finely structured extinction profiles, and broad band optical absorption. The 3D nature of the devices can overcome intrinsic difficulties related to conventional architectures in a wide range of multidisciplinary applications. © 2013 American Chemical Society.

  3. Preparation and Application of Hollow Silica/magnetic Nanocomposite Particle

    Science.gov (United States)

    Wang, Cheng-Chien; Lin, Jing-Mo; Lin, Chun-Rong; Wang, Sheng-Chang

    The hollow silica/cobalt ferrite (CoFe2O4) magnetic microsphere with amino-groups were successfully prepared via several steps, including preparing the chelating copolymer microparticles as template by soap-free emulsion polymerization, manufacturing the hollow cobalt ferrite magnetic microsphere by in-situ chemical co-precipitation following calcinations, and surface modifying of the hollow magnetic microsphere by 3-aminopropyltrime- thoxysilane via the sol-gel method. The average diameter of polymer microspheres was ca. 200 nm from transmission electron microscope (TEM) measurement. The structure of the hollow magnetic microsphere was characterized by using TEM and scanning electron microscope (SEM). The spinel-type lattice of CoFe2O4 shell layer was identified by using XRD measurement. The diameter of CoFe2O4 crystalline grains ranged from 54.1 nm to 8.5 nm which was estimated by Scherrer's equation. Additionally, the hollow silica/cobalt ferrite microsphere possesses superparamagnetic property after VSM measurement. The result of BET measurement reveals the hollow magnetic microsphere which has large surface areas (123.4m2/g). After glutaraldehyde modified, the maximum value of BSA immobilization capacity of the hollow magnetic microsphere was 33.8 mg/g at pH 5.0 buffer solution. For microwave absorption, when the hollow magnetic microsphere was compounded within epoxy resin, the maximum reflection loss of epoxy resins could reach -35dB at 5.4 GHz with 1.9 mm thickness.

  4. Monodisperse Hollow Tricolor Pigment Particles for Electronic Paper

    Directory of Open Access Journals (Sweden)

    Meng Xianwei

    2009-01-01

    Full Text Available Abstract A general approach has been designed to blue, green, and red pigments by metal ions doping hollow TiO 2. The reaction involves initial formation of PS at TiO2 core–shell nanoparticles via a mixed-solvent method, and then mixing with metal ions solution containing PEG, followed calcining in the atmosphere. The as-prepared hollow pigments exhibit uniform size, bright color, and tunable density, which are fit for electronic paper display.

  5. Control of Dispersion in Hollow Core Photonic Crystal Fibers

    DEFF Research Database (Denmark)

    Roberts, John

    2007-01-01

    The dispersion of hollow core photonic crystal fibers can be tailored by modifying a single ring of holes in the cladding. The dispersion can be lowered and flattened, or alternatively greatly increased, in a controlled manner.......The dispersion of hollow core photonic crystal fibers can be tailored by modifying a single ring of holes in the cladding. The dispersion can be lowered and flattened, or alternatively greatly increased, in a controlled manner....

  6. Thin-walled reinforcement lattice structure for hollow CMC buckets

    Science.gov (United States)

    de Diego, Peter

    2017-06-27

    A hollow ceramic matrix composite (CMC) turbine bucket with an internal reinforcement lattice structure has improved vibration properties and stiffness. The lattice structure is formed of thin-walled plies made of CMC. The wall structures are arranged and located according to high stress areas within the hollow bucket. After the melt infiltration process, the mandrels melt away, leaving the wall structure to become the internal lattice reinforcement structure of the bucket.

  7. Highly efficient fluorescence sensing with hollow core photonic crystal fibers

    DEFF Research Database (Denmark)

    Smolka, Stephan; Barth, Michael; Benson, Oliver

    2008-01-01

    We investigate hollow core photonic crystal fibers for ultra-sensitive fluorescence detection by selectively infiltrating the central hole with fluorophores. Dye concentrations down to 10(-9) M can be detected using only nanoliter sample volumes.......We investigate hollow core photonic crystal fibers for ultra-sensitive fluorescence detection by selectively infiltrating the central hole with fluorophores. Dye concentrations down to 10(-9) M can be detected using only nanoliter sample volumes....

  8. A High Current Proton Linac with 352 MHz SC Cavities

    CERN Document Server

    Pagani, C; Pierini, P

    1996-01-01

    A proposal for a 10-120 mA proton linac employing superconducting beta-graded, CERN type, four cell cavities at 352 MHz is presented. The high energy part (100 MeV-1 GeV) of the machine is split in three beta-graded sections, and transverse focusing is provided via a periodic doublet array. All the parameters, like power in the couplers and accelerating fields in the cavities, are within the state of the art, achieved in operating machines. A first stage of operation at 30 mA beam current is proposed, while the upgrade of the machine to 120 mA operation can be obtained increasing the number of klystrons and couplers per cavity. The additional coupler ports, up to four, will be integrated in the cavity design. Preliminary calculations indicate that beam transport is feasible, given the wide aperture of the 352 MHz structures. A capital cost of less than 100 M$ at 10 mA, reaching up to 280 M$ for the 120 mA extension, has been estimated for the superconducting high energy section (100 MeV-1 GeV). The high effic...

  9. Design Considerations for the LHC 200 MHz RF System

    CERN Document Server

    Boussard, Daniel; Kindermann, H P; Linnecar, Trevor Paul R; Marque, S; Tückmantel, Joachim

    2000-01-01

    The longitudinal beam transfer from the SPS into the LHC 400 MHz buckets will not be free of losses without a lower frequency capture system and a fast longitudinal damping system in LHC. We present a complete study of a combined system using four identical copper cavities at 200 MHz delivering 3 MV total CW voltage and having still enough bandwidth to achieve fast longitudinal damping. The shape of a cavity was designed according to the accelerating mode performance, its tuning and the higher order mode spectrum with respect to the LHC beam lines and their possible attenuation. The possibility to park the cavities during coast was included. The local heat load and the corresponding cooling water distribution as well as deformations were studied and techniques to build the cavity with all ports at low cost are proposed. The parameters of the RF generators, couplers and detuning are determined. Simulations of the total LHC RF system incorporating real delays, generator bandwidth and the control loops confirm t...

  10. Mechanical design and fabrication of a 425-MHz H- buncher

    International Nuclear Information System (INIS)

    Wilson, N.G.; Precechtel, D.

    1987-01-01

    A beam buncher has been designed, fabricated, and installed on the accelerator test stand (ATS) to match the 2-MeV output beam of a 425-MHz H - radio-frequency quadrupole (RFQ) into a 425-MHz drift-tube linac (DTL). The buncher configuration provides integral-matching permanent-magnet quadrupoles (PMQ) at the exit of the RFQ and one βλ across the buncher accelerating gap; a third PMQ is the first DTL half-cell magnet. Located between the second and third PMQs is a 50-Ω, capacitively coupled, beam-sensing pickup loop. Cooling channels are provided in each of the brazed OFHC copper wall sections. Vacuum pumping of the buncher is provided by a cryogenic refrigerator vacuum pump through an array of small-diameter holes in the buncher cavity wall. Mechanical features of the buncher, the brazing and electron-beam welding of the solid-copper buncher structure, and the beam pickup loop are described in this paper. The buncher has been tuned, installed, and operated at full power on the ATS

  11. Experimental Limits on Gravitational Waves in the MHz frequency Range

    Energy Technology Data Exchange (ETDEWEB)

    Lanza, Robert Jr. [Univ. of Chicago, IL (United States)

    2015-03-01

    This thesis presents the results of a search for gravitational waves in the 1-11MHz frequency range using dual power-recycled Michelson laser interferometers at Fermi National Accelerator Laboratory. An unprecedented level of sensitivity to gravitational waves in this frequency range has been achieved by cross-correlating the output fluctuations of two identical and colocated 40m long interferometers. This technique produces sensitivities better than two orders of magnitude below the quantum shot-noise limit, within integration times of less than 1 hour. 95% confidence level upper limits are placed on the strain amplitude of MHz frequency gravitational waves at the 10-21 Hz-1/2 level, constituting the best direct limits to date at these frequencies. For gravitational wave power distributed over this frequency range, a broadband upper limit of 2.4 x 10-21Hz-1/2 at 95% confidence level is also obtained. This thesis covers the detector technology, the commissioning and calibration of the instrument, the statistical data analysis, and the gravitational wave limit results. Particular attention is paid to the end-to-end calibration of the instrument’s sensitivity to differential arm length motion, and so to gravitational wave strain. A detailed statistical analysis of the data is presented as well.

  12. VLA observations of NGC 1265 at 4886 MHz

    International Nuclear Information System (INIS)

    Owen, F.N.; Burns, J.O.; Rudnick, L.

    1978-01-01

    Observations are presented of the head-tail radio galaxy NGC 1265, made with the VLA at 4886 MHz. The total intensity brightness distribution has a resolution of 1' x 1'.5 and an rms noise of approx.150 μJy/beam area. These observations, combined with data at 2695 and 8085 MHz on a 35 km baseline in Green Bank, show that the nuclear component is less than 0'.1 and has a slightly inverted spectrum.The VLA map reveals a narrow continuous stream of emission leading away from the nucleus and out into the lower-surface brightness tail. Several small knots are superposed on the stream. This brightness distribution is compared with the independent-blob model of Jaffe and Perola. We find that the brightness distribution predicted by this model does not agree well with the observed brightness distribution. We suggest that a hot interstellar medium in the galaxy may be necessary to explain the complex structure

  13. Very high frequency (beyond 100 MHz) PZT kerfless linear arrays.

    Science.gov (United States)

    Wu, Da-Wei; Zhou, Qifa; Geng, Xuecang; Liu, Chang-Geng; Djuth, Frank; Shung, K Kirk

    2009-10-01

    This paper presents the design, fabrication, and measurements of very high frequency kerfless linear arrays prepared from PZT film and PZT bulk material. A 12-microm PZT thick film fabricated from PZT-5H powder/solution composite and a piece of 15-microm PZT-5H sheet were used to fabricate 32-element kerfless high-frequency linear arrays with photolithography. The PZT thick film was prepared by spin-coating of PZT sol-gel composite solution. The thin PZT-5H sheet sample was prepared by lapping a PZT-5H ceramic with a precision lapping machine. The measured results of the 2 arrays were compared. The PZT film array had a center frequency of 120 MHz, a bandwidth of 60% with a parylene matching layer, and an insertion loss of 41 dB. The PZT ceramic sheet array was found to have a center frequency of 128 MHz with a poorer bandwidth (40% with a parylene matching layer) but a better sensitivity (28 dB insertion loss).

  14. Resonance Frequency Readout Circuit for a 900 MHz SAW Device.

    Science.gov (United States)

    Liu, Heng; Zhang, Chun; Weng, Zhaoyang; Guo, Yanshu; Wang, Zhihua

    2017-09-15

    A monolithic resonance frequency readout circuit with high resolution and short measurement time is presented for a 900 MHz RF surface acoustic wave (SAW) sensor. The readout circuit is composed of a fractional-N phase-locked loop (PLL) as the stimulus source to the SAW device and a phase-based resonance frequency detecting circuit using successive approximation (SAR). A new resonance frequency searching strategy has been proposed based on the fact that the SAW device phase-frequency response crosses zero monotonically around the resonance frequency. A dedicated instant phase difference detecting circuit is adopted to facilitate the fast SAR operation for resonance frequency searching. The readout circuit has been implemented in 180 nm CMOS technology with a core area of 3.24 mm². In the experiment, it works with a 900 MHz SAW resonator with a quality factor of Q = 130. Experimental results show that the readout circuit consumes 7 mW power from 1.6 V supply. The frequency resolution is 733 Hz, and the relative accuracy is 0.82 ppm, and it takes 0.48 ms to complete one measurement. Compared to the previous results in the literature, this work has achieved the shortest measurement time with a trade-off between measurement accuracy and measurement time.

  15. Polymer coatings as separator layers for microbial fuel cell cathodes

    KAUST Repository

    Watson, Valerie J.; Saito, Tomonori; Hickner, Michael A.; Logan, Bruce E.

    2011-01-01

    and increased coulombic efficiency (CE = 56-64%) relative to an uncoated cathode (29 ± 8%), but decreased power production (255-574 mW m-2). Electrochemical characterization of the cathodes ex situ to the MFC showed that the cathodes with the lowest charge

  16. Coating for lithium anode, thionyl chloride active cathode electrochemical cell

    Energy Technology Data Exchange (ETDEWEB)

    Catanzarite, V.O.

    1983-01-04

    Electrochemical power cells having a cathode current collector, a combination liquid active cathode depolarizer electrolyte solvent and an anode that forms surface compounds when in intimate contact with the liquid cathode are enhanced by the addition of a passivation limiting film contiguous to said anode. The passivating film is a member of the cyanoacrilate family of organic compounds.

  17. Coating for lithium anode, thionyl chloride active cathode electrochemical cell

    Energy Technology Data Exchange (ETDEWEB)

    Catanzarite, V.O.

    1981-10-20

    Electrochemical power cells having a cathode current collector, a combination liquid active cathode depolarizer electrolyte solvent and an anode that forms surface compounds when in intimate contact with the liquid cathode are enhanced by the addition of a passivation limiting film contiguous to said anode. The passivating film is a member of the cyanoacrilate family of organic compounds.

  18. Cold cathodes on ultra-dispersed diamond base

    International Nuclear Information System (INIS)

    Alimova, A.N.; Zhirnov, V.V.; Chubun, N.N.; Belobrov, P.I.

    1998-01-01

    Prospects of application of nano diamond powders for fabrication of cold cathodes are discussed.Cold cathodes based on silicon pointed structures with nano diamond coatings were prepared.The deposition technique of diamond coating was dielectrophoresis from suspension of nano diamond powder in organic liquids.The cathodes were tested in sealed prototypes of vacuum electronic devices

  19. Explosive-emission cathode fabricated using track method

    International Nuclear Information System (INIS)

    Akap'ev, G.N.; Korenev, S.A.

    1989-01-01

    Fabrication technique for large area multipoint cathodes is described. The technique is based on channels filling with metal in the ion-irradiated dielectric film producted after channel etching. It is shown, that cathode may be used under explosive emission conditions. Characteristics of diode with the mentioned type cathodes are measured

  20. Q0 Degradation of LANL 700-MHZ β = 0.64 Elliptical Cavities and ANL 340 MHZ Spoke Cavities

    International Nuclear Information System (INIS)

    Tajima, Tsuyoshi; Chan, Kwok-Chi D.; Edwards, Randall L.; Gentzlinger, Robert C.; Kelley, John Patrick; Krawczyk, Frank L.; Madrid, Michael A.; Montoya, Debbie I.; Schrage, Dale L.; Shapiro, Alan H.

    2002-01-01

    The quality factor (Q 0 ) of most of the six LANL β = 0.64 700-MHz 5-cell elliptical cavities starts to drop at E acc = 8-10 MV/m, which may be related to multipacting. Residual resistances of these cavities were measured to be 5.0-7.6 n(Omega). The sensitivity of surface resistance to the external magnetic field was measured to be 0.22 n(Omega)/mG. Q disease tests have shown no significant Q 0 degradation for both elliptical cavities and a spoke cavity with our 100 (micro)m BCP.