Science.gov

Sample records for ion chamber response

  1. Response of large cavity ion chambers to space protons

    NASA Technical Reports Server (NTRS)

    Wilson, J. W.; Khandelwal, G. S.

    1981-01-01

    The assumption that spherical-shell ion chamber rssponse is equal to the dose in the center of the cavity is found to be a poor approximation for ion chambers used for area monitoring in the space program. The dose response is calculated using the appropriate areal density distribution function. Effects of nuclear reaction are evaluated using proton buildup factors. Errors of up to 100% are found for some components of the space radiation environments.

  2. Response of air-filled ion chambers to high-intensity radiation pulses

    SciTech Connect

    Plum, M.; Brown, D.

    1993-06-01

    Ion chambers are one of the most popular types of detectors used for beam loss-monitor systems. To provide a foundation for the development of future loss-monitor systems, and to fully characterize the ion chambers in use at LAMPF, we have studied the response of air-filled cylindrical ion chambers to high-intensity, short-duration radiation pulses. The most intense pulses were about 180 rad in 250 ns (the equivalent steady-state dose rate was about 700 Mrad/h). We filled our chambers with nitrogen gas at 760 Torr and air at 600 Torr. The ion chambers were driven into extreme nonlinear response. We hope these data will be used to design loss-monitor systems based on air-filled ion chambers, thus eliminating the need for gas-flow systems and/or airtight ion chambers.

  3. Response of air-filled ion chambers to high-intensity radiation pulses

    SciTech Connect

    Plum, M.; Brown, D.

    1993-01-01

    Ion chambers are one of the most popular types of detectors used for beam loss-monitor systems. To provide a foundation for the development of future loss-monitor systems, and to fully characterize the ion chambers in use at LAMPF, we have studied the response of air-filled cylindrical ion chambers to high-intensity, short-duration radiation pulses. The most intense pulses were about 180 rad in 250 ns (the equivalent steady-state dose rate was about 700 Mrad/h). We filled our chambers with nitrogen gas at 760 Torr and air at 600 Torr. The ion chambers were driven into extreme nonlinear response. We hope these data will be used to design loss-monitor systems based on air-filled ion chambers, thus eliminating the need for gas-flow systems and/or airtight ion chambers.

  4. Three chamber negative ion source

    DOEpatents

    Leung, Ka-Ngo; Ehlers, Kenneth W.; Hiskes, John R.

    1985-01-01

    A negative ion vessel is divided into an excitation chamber, a negative ionization chamber and an extraction chamber by two magnetic filters. Input means introduces neutral molecules into a first chamber where a first electron discharge means vibrationally excites the molecules which migrate to a second chamber. In the second chamber a second electron discharge means ionizes the molecules, producing negative ions which are extracted into or by a third chamber. A first magnetic filter prevents high energy electrons from entering the negative ionization chamber from the excitation chamber. A second magnetic filter prevents high energy electrons from entering the extraction chamber from the negative ionizing chamber. An extraction grid at the end of the negative ion vessel attracts negative ions into the third chamber and accelerates them. Another grid, located adjacent to the extraction grid, carries a small positive voltage in order to inhibit positive ions from migrating into the extraction chamber and contour the plasma potential. Additional electrons can be suppressed from the output flux using ExB forces provided by magnetic field means and the extractor grid electric potential.

  5. SU-F-303-15: Ion Chamber Dose Response in Magnetic Fields as a Function of Incident Photon Energy

    SciTech Connect

    Malkov, V. N.; Rogers, D. W. O.

    2015-06-15

    Purpose: In considering the continued development of synergetic MRI-radiation therapy machines, we seek to quantify the variability of ion chamber response per unit dose in the presence of magnetic fields of varying strength as a function of incident photon beam quality and geometric configuration. Methods: To account for the effect of magnetic fields on the trajectory of charged particles a new algorithm was introduced into the EGSnrc Monte Carlo code. In the egs-chamber user code the dose to the cavity of an NE2571 ion chamber is calculated in two configurations, in 0 to 2 T magnetic fields, with an incoming parallel 10×10 cm{sup 2} photon beam with energies ranging between 0.5 MeV and 8 MeV. In the first, the photon beam is incident on the long-axis of the ion chamber (config-1), and in the second the beam is parallel to the long-axis and incident from the conical end of the chamber (config-2). For both, the magnetic field is perpendicular to the direction of the beam and the long axis of the chamber. Results: The ion chamber response per unit dose to water at the same point is determined as a function of magnetic field and is normalized to the 0T case for each of incoming photon energies. For both configurations, accurate modeling of the ion chamber yielded closer agreement with the experimental results obtained by Meijsing et. al (2009). Config-1 yields a gradual increase in response with increasing field strength to a maximum of 13.4% and 1.4% for 1 MeV and 8 MeV photon beams, respectively. Config-2 produced a decrease in response of up to 6% and 13% for 0.5 MeV and 8 MeV beams, respectively. Conclusion: These results provide further support for ion chamber calibration in MRI-radiotherapy coupled systems and demonstrates noticeable energy dependence for clinically relevant fields.

  6. Ion chamber based neutron detectors

    DOEpatents

    Derzon, Mark S; Galambos, Paul C; Renzi, Ronald F

    2014-12-16

    A neutron detector with monolithically integrated readout circuitry, including: a bonded semiconductor die; an ion chamber formed in the bonded semiconductor die; a first electrode and a second electrode formed in the ion chamber; a neutron absorbing material filling the ion chamber; and the readout circuitry which is electrically coupled to the first and second electrodes. The bonded semiconductor die includes an etched semiconductor substrate bonded to an active semiconductor substrate. The readout circuitry is formed in a portion of the active semiconductor substrate. The ion chamber has a substantially planar first surface on which the first electrode is formed and a substantially planar second surface, parallel to the first surface, on which the second electrode is formed. The distance between the first electrode and the second electrode may be equal to or less than the 50% attenuation length for neutrons in the neutron absorbing material filling the ion chamber.

  7. Measurement of surface alpha contamination using electret ion chambers.

    PubMed

    Dua, S K; Biswas, S K; Szerszen, P; Boudreaux, J; Ebadian, M A

    1999-06-01

    Electret ion chambers are inexpensive, light-weight, commercially available, passive charge-integrating devices for accurate measurement of different radiations. Performance of electret ion chambers for surface alpha contamination measurement was evaluated. Ion chambers of two types and electrets of three thicknesses were used for the study. Calibration of the electret ion chambers was performed using reference alpha standards of different energies and radioactivities. Effects of various parameters such as chamber dimensions, electret thickness, alpha particle energy, position of alpha source from the chamber centerline, source localized or uniformly distributed, level of alpha contamination, Mylar window covering the chamber, and ambient radon and gamma radiation on the response of the electret ion chambers were determined. Suitable combinations of chambers and electrets to measure surface alpha contamination were determined.

  8. Compact ion chamber based neutron detector

    DOEpatents

    Derzon, Mark S.; Galambos, Paul C.; Renzi, Ronald F.

    2015-10-27

    A directional neutron detector has an ion chamber formed in a dielectric material; a signal electrode and a ground electrode formed in the ion chamber; a neutron absorbing material filling the ion chamber; readout circuitry which is electrically coupled to the signal and ground electrodes; and a signal processor electrically coupled to the readout circuitry. The ion chamber has a pair of substantially planar electrode surfaces. The chamber pressure of the neutron absorbing material is selected such that the reaction particle ion trail length for neutrons absorbed by the neutron absorbing material is equal to or less than the distance between the electrode surfaces. The signal processor is adapted to determine a path angle for each absorbed neutron based on the rise time of the corresponding pulse in a time-varying detector signal.

  9. Fast-response cloud chamber

    NASA Technical Reports Server (NTRS)

    Fogal, G. L.

    1977-01-01

    Wall structure keeps chambers at constant, uniform temperature, yet allows them to be cooled rapidly if necessary. Wall structure, used in fast-response cloud chamber, has surface heater and coolant shell separated by foam insulation. It is lightweight and requires relatively little power.

  10. Three chamber negative ion source

    DOEpatents

    Leung, K.N.; Ehlers, K.W.; Hiskes, J.R.

    1983-11-10

    It is an object of this invention provide a negative ion source which efficiently provides a large flux of negatively ionized particles. This invention provides a volume source of negative ions which has a current density sufficient for magnetic fusion applications and has electrons suppressed from the output. It is still another object of this invention to provide a volume source of negative ions which can be electrostatically accelerated to high energies and subsequently neutralized to form a high energy neutral beam for use with a magnetically confined plasma.

  11. Chamber transport for heavy ion fusion

    NASA Astrophysics Data System (ADS)

    Olson, Craig L.

    2014-01-01

    A brief review is given of research on chamber transport for HIF (heavy ion fusion) dating from the first HIF Workshop in 1976 to the present. Chamber transport modes are categorized into ballistic transport modes and channel-like modes. Four major HIF reactor studies are summarized (HIBALL-II, HYLIFE-II, Prometheus-H, OSIRIS), with emphasis on the chamber transport environment. In general, many beams are used to provide the required symmetry and to permit focusing to the required small spots. Target parameters are then discussed, with a summary of the individual heavy ion beam parameters required for HIF. The beam parameters are then classified as to their line charge density and perveance, with special emphasis on the perveance limits for radial space charge spreading, for the space charge limiting current, and for the magnetic (Alfven) limiting current. The major experiments on ballistic transport (SFFE, Sabre beamlets, GAMBLE II, NTX, NDCX) are summarized, with specific reference to the axial electron trapping limit for charge neutralization. The major experiments on channel-like transport (GAMBLE II channel, GAMBLE II self-pinch, LBNL channels, GSI channels) are discussed. The status of current research on HIF chamber transport is summarized, and the value of future NDCX-II transport experiments for the future of HIF is noted.

  12. Recombination characteristics of therapeutic ion beams on ion chamber dosimetry

    NASA Astrophysics Data System (ADS)

    Matsufuji, Naruhiro; Matsuyama, Tetsuharu; Sato, Shinji; Kohno, Toshiyuki

    2016-09-01

    In heavy ion radiotherapy, ionization chambers are regarded as a standard for determining the absorbed dose given to patients. In ion dosimetry, it is necessary to correct the radiation quality, which depends on the initial recombination effect. This study reveals for the radiation quality dependence of the initial recombination in air in ion dosimetry. Ionization charge was measured for the beams of protons at 40-160 MeV, carbon at 21-400 MeV/n, and iron at 23.5-500 MeV/n using two identical parallel-plate ionization chambers placed in series along the beam axis. The downstream chamber was used as a monitor operated with a constant applied voltage, while the other chamber was used for recombination measurement by changing the voltage. The ratio of the ionization charge measured by the two ionization chambers showed a linear relationship with the inverse of the voltage in the high-voltage region. The initial recombination factor was estimated by extrapolating the obtained linear relationship to infinite voltage. The extent of the initial recombination was found to increase with decreasing incident energy or increasing atomic number of the beam. This behavior can be explained with an amorphous track structure model: the increase of ionization density in the core region of the track due to decreasing kinetic energy or increasing atomic number leads to denser initial ion production and results in a higher recombination probability. For therapeutic carbon ion beams, the extent of the initial recombination was not constant but changed by 0.6% even in the target region. This tendency was quantitatively well reproduced with the track-structure based on the initial recombination model; however, the transitional change in the track structure is considered to play an important role in further understanding of the characteristics of the initial recombination.

  13. Vacuum chamber for ion manipulation device

    SciTech Connect

    Chen, Tsung-Chi; Tang, Keqi; Ibrahim, Yehia M; Smith, Richard D; Anderson, Gordon A; Baker, Erin M

    2014-12-09

    An ion manipulation method and device is disclosed. The device includes a pair of substantially parallel surfaces. An array of inner electrodes is contained within, and extends substantially along the length of, each parallel surface. The device includes a first outer array of electrodes and a second outer array of electrodes. Each outer array of electrodes is positioned on either side of the inner electrodes, and is contained within and extends substantially along the length of each parallel surface. A DC voltage is applied to the first and second outer array of electrodes. A RF voltage, with a superimposed electric field, is applied to the inner electrodes by applying the DC voltages to each electrode. Ions either move between the parallel surfaces within an ion confinement area or along paths in the direction of the electric field, or can be trapped in the ion confinement area. A predetermined number of pairs of surfaces are disposed in one or more chambers, forming a multiple-layer ion mobility cyclotron device.

  14. Measurement of alpha particle energy using windowless electret ion chambers.

    PubMed

    Dua, S K; Kotrappa, P; Srivastava, R; Ebadian, M A; Stieff, L R

    2002-10-01

    Electret ion chambers are inexpensive, lightweight, robust, commercially available, passive, charge-integrating devices for accurate measurement of different ionizing radiations. In an earlier work a chamber of dimensions larger than the range of alpha particles having aluminized Mylar windows of different thickness was used for measurement of alpha radiation. Correlation between electret mid-point voltage, alpha particle energy, and response was developed and it was shown that this chamber could be used for estimating the effective energy of an unknown alpha source. In the present study, the electret ion chamber is used in the windowless mode so that the alpha particles dissipate their entire energy inside the volume, and the alpha particle energy is determined from the first principles. This requires that alpha disintegration rate be accurately known or measured by an alternate method. The measured energies were within 1 to 4% of the true values for different sources (230Th, 237Np, 239Pu, 241Am, and 224Cm). This method finds application in quantitative determination of alpha energy absorbed in thin membrane and, hence, the absorbed dose.

  15. SU-C-304-01: Investigation of Various Detector Response Functions and Their Geometry Dependence in a Novel Method to Address Ion Chamber Volume Averaging Effect

    SciTech Connect

    Barraclough, B; Lebron, S; Li, J; Fan, Qiyong; Liu, C; Yan, G

    2015-06-15

    Purpose: A novel convolution-based approach has been proposed to address ion chamber (IC) volume averaging effect (VAE) for the commissioning of commercial treatment planning systems (TPS). We investigate the use of various convolution kernels and its impact on the accuracy of beam models. Methods: Our approach simulates the VAE by iteratively convolving the calculated beam profiles with a detector response function (DRF) while optimizing the beam model. At convergence, the convolved profiles match the measured profiles, indicating the calculated profiles match the “true” beam profiles. To validate the approach, beam profiles of an Elekta LINAC were repeatedly collected with ICs of various volumes (CC04, CC13 and SNC 125) to obtain clinically acceptable beam models. The TPS-calculated profiles were convolved externally with the DRF of respective IC. The beam model parameters were reoptimized using Nelder-Mead method by forcing the convolved profiles to match the measured profiles. We evaluated three types of DRFs (Gaussian, Lorentzian, and parabolic) and the impact of kernel dependence on field geometry (depth and field size). The profiles calculated with beam models were compared with SNC EDGE diode-measured profiles. Results: The method was successfully implemented with Pinnacle Scripting and Matlab. The reoptimization converged in ∼10 minutes. For all tested ICs and DRFs, penumbra widths of the TPS-calculated profiles and diode-measured profiles were within 1.0 mm. Gaussian function had the best performance with mean penumbra width difference within 0.5 mm. The use of geometry dependent DRFs showed marginal improvement, reducing the penumbra width differences to less than 0.3 mm. Significant increase in IMRT QA passing rates was achieved with the optimized beam model. Conclusion: The proposed approach significantly improved the accuracy of the TPS beam model. Gaussian functions as the convolution kernel performed consistently better than Lorentzian and

  16. Polarity and ion recombination corrections in continuous and pulsed beams for ionization chambers with high Z chamber walls.

    PubMed

    Aldosary, Ghada; Safigholi, Habib; Song, William; Seuntjens, Jan; Sarfehnia, Arman

    2017-03-01

    In this work, the response of Farmer-type ionization chambers fitted with high atomic number (Z) walls is studied, and results of the effects of such walls on polarity and ion recombination correction factors in both continuous and pulsed beams are presented. Measurements were made in a continuous Co-60 beam and a pulsed 6MV linac beam using an Exradin-A12 ionization chamber fitted with the manufacturer's C-552 plastic wall, as well as geometrically identical walls made from aluminum, copper and molybdenum. The bias voltage was changed between 10values (range: +50 to +560V). Ion recombination was determined from Jaffé plots and by using the "two-voltage technique". The saturation charge measured with each chamber wall was extrapolated from Jaffé plots. Additionally, the effect of different wall materials on chamber response was studied using MCNP simulations. Results showed that the polarity correction factor is not significantly affected by changes in chamber wall material (within 0.1%). Furthermore, although the saturation charges greatly vary with each chamber wall material, and charge multiplication increases for higher atomic number wall materials, the standard methods of calculating ion recombination yielded results that differed by only 0.2%. Therefore, polarity and ion recombination correction factors are not greatly affected by the chamber wall material. The experimental saturation charges for all the different wall materials agreed well within the uncertainty with MCNP simulations. The breakdown of the linear relationship in Jaffé plots that was previously reported to exist for conventional chamber walls was also observed with the different wall materials.

  17. Calibration of the borated ion chamber at NIST reactor thermal column.

    PubMed

    Wang, Z; Hertel, N E; Lennox, A

    2007-01-01

    In boron neutron capture therapy and boron neutron capture enhanced fast neutron therapy, the absorbed dose of tissue due to the boron neutron capture reaction is difficult to measure directly. This dose can be computed from the measured thermal neutron fluence rate and the (10)B concentration at the site of interest. A borated tissue-equivalent (TE) ion chamber can be used to directly measure the boron dose in a phantom under irradiation by a neutron beam. Fermilab has two Exradin 0.5 cm(3) Spokas thimble TE ion chambers, one loaded with boron, available for such measurements. At the Fermilab Neutron Therapy Facility, these ion chambers are generally used with air as the filling gas. Since alpha particles and lithium ions from the (10)B(n,alpha)(7)Li reactions have very short ranges in air, the Bragg-Gray principle may not be satisfied for the borated TE ion chamber. A calibration method is described in this paper for the determination of boron capture dose using paired ion chambers. The two TE ion chambers were calibrated in the thermal column of the National Institute of Standards and Technology (NIST) research reactor. The borated TE ion chamber is loaded with 1,000 ppm of natural boron (184 ppm of (10)B). The NIST thermal column has a cadmium ratio of greater than 400 as determined by gold activation. The thermal neutron fluence rate during the calibration was determined using a NIST fission chamber to an accuracy of 5.1%. The chambers were calibrated at two different thermal neutron fluence rates: 5.11 x 10(6) and 4.46 x 10(7)n cm(-2) s(-1). The non-borated ion chamber reading was used to subtract collected charge not due to boron neutron capture reactions. An optically thick lithium slab was used to attenuate the thermal neutrons from the neutron beam port so the responses of the chambers could be corrected for fast neutrons and gamma rays in the beam. The calibration factor of the borated ion chamber was determined to be 1.83 x 10(9) +/- 5.5% (+/- 1sigma) n

  18. Chamber transport of ''foot'' pulses for heavy-ion fusion

    SciTech Connect

    Sharp, W.M.; Callahan-Miller, D.A.; Tabak, M.; Yu, S.S.; Peterson, P.F.

    2002-02-20

    Indirect-drive targets for heavy-ion fusion must initially be heated by ''foot'' pulses that precede the main heating pulses by tens of nanoseconds. These pulses typically have a lower energy and perveance than the main pulses, and the fusion-chamber environment is different from that seen by later pulses. The preliminary particle-in-cell simulations of foot pulses here examine the sensitivity of the beam focusing to ion-beam perveance, background-gas density, and pre-neutralization by a plasma near the chamber entry port.

  19. Realistic modeling of chamber transport for heavy-ion fusion

    SciTech Connect

    Sharp, W.M.; Grote, D.P.; Callahan, D.A.; Tabak, M.; Henestroza, E.; Yu, S.S.; Peterson, P.F.; Welch, D.R.; Rose, D.V.

    2003-05-01

    Transport of intense heavy-ion beams to an inertial-fusion target after final focus is simulated here using a realistic computer model. It is found that passing the beam through a rarefied plasma layer before it enters the fusion chamber can largely neutralize the beam space charge and lead to a usable focal spot for a range of ion species and input conditions.

  20. Modeling Chamber Transport for Heavy-Ion Fusion

    SciTech Connect

    Sharp, W M; Niller, D A C; Tabak, M; Yu, S S; Peterson, P F; Welch, D R; Rose, D V; Olson, C L

    2002-08-02

    In a typical thick-liquid-wall scenario for heavy-ion fusion (HIF), between seventy and two hundred high-current beams enter the target chamber through ports and propagate about three meters to the target. Since molten-salt jets are planned to protect the chamber wall, the beams move through vapor from the jets, and collisions between beam ions and this background gas both strip the ions and ionize the gas molecules. Radiation from the preheated target causes further beam stripping and gas ionization. Due to this stripping, beams for heavy-ion fusion are expected to require substantial neutralization in a target chamber. Much recent research has, therefore, focused on beam neutralization by electron sources that were neglected in earlier simulations, including emission from walls and the target, photoionization by the target radiation, and pre-neutralization by a plasma generated along the beam path. When these effects are included in simulations with practicable beam and chamber parameters, the resulting focal spot is approximately the size required by a distributed radiator target.

  1. Modeling chamber transport for heavy-ion fusion

    SciTech Connect

    Sharp, W.M.; Callahan, D.A.; Tabak, M.; Yu, S.S.; Peterson, P.F.; Welch, D.R.; Rose, D.V.; Olson, C.L.

    2002-10-01

    In a typical thick-liquid-wall scenario for heavy-ion fusion (HIF), between seventy and two hundred high-current beams enter the target chamber through ports and propagate about three meters to the target. Since molten-salt jets are planned to protect the chamber wall, the beams move through vapor from the jets, and collisions between beam ions and this background gas both strip the ions and ionize the gas molecules. Radiation from the preheated target causes further beam stripping and gas ionization. Due to this stripping, beams for heavy-ion fusion are expected to require substantial neutralization in a target chamber. Much recent research has, therefore, focused on beam neutralization by electron sources that were neglected in earlier simulations, including emission from walls and the target, photoionization by the target radiation, and pre-neutralization by a plasma generated along the beam path. When these effects are included in simulations with practicable beam and chamber parameters, the resulting focal spot is approximately the size required by a distributed radiator target.

  2. Leakage correction estimate for electret ion chamber dielectric material used for long-term environmental gamma monitoring.

    PubMed

    Jones, David F; Paulus, L R

    2008-05-01

    The Idaho Department of Environmental Quality INL Oversight Program (DEQ-INL) operates an environmental gamma radiation detection network consisting of a series of high-pressure ion chambers to provide real-time ambient radiation measurements and a series of passive environmental electret ion chambers to increase coverage area and measure cumulative dose over a calendar quarter. DEQ-INL has identified a consistent over-response of approximately 40% by the electret ion chambers with respect to co-located high-pressure ion chambers since 1998. DEQ-INL conducted a series of three investigations to quantify this over-response. The over-response is likely attributable to a number of factors, including inherent voltage loss by the electret material not due to ionization within the chamber. One aspect of the investigation verified the manufacturer's calibration factor used to convert decrease in voltage to exposure. Additional investigations were performed that identified an average electret voltage loss of 0.2 V d(-1). When this voltage correction was applied to historical environmental data, electret ion chamber response was within 10% of the co-located high-pressure ion chamber response.

  3. Charges and current induced by moving ions in multiwire chambers

    NASA Astrophysics Data System (ADS)

    Erskine, G. A.

    1982-07-01

    A method for calculating the charges induced on the grid wires, and on cathode strips parallel to the grid wires, by a point charge in a multiwire chamber is described. The method is applied to the calculation, as a function of time, of the charge and current induced by a small group of positive ions moving in accordance with the drift equation v= μE where v is the velocity. An appendix lists a number of formulae relating to the electrostatic field of a multiwire chamber.

  4. Beam loss ion chamber system upgrade for experimental halls

    SciTech Connect

    D. Dotson; D. Seidman

    2005-08-01

    The Beam loss Ion Chamber System (BLICS) was developed to protect Jefferson Labs transport lines, targets and beam dumps from a catastrophic ''burn through''. Range changes and testing was accomplished manually requiring the experiment to be shut down. The new upgraded system is based around an ''off the shelf'' Programmable Logic Controller located in a single control box supporting up to ten individual detectors. All functions that formerly required an entry into the experimental hall and manual adjustment can be accomplished from the Machine Control Center (MCC). A further innovation was the addition of a High Voltage ''Brick'' at the detector location. A single cable supplies the required voltage for the Brick and a return line for the ion chamber signal. The read back screens display range, trip point, and accumulated dose for each location. The new system is very cost effective and significantly reduces the amount of lost experimental time.

  5. Beam Loss Ion Chamber System Upgrade for Experimental Halls

    SciTech Connect

    D.W. Dotson; D.J. Seidman

    2005-05-16

    The Beam loss Ion Chamber System (BLICS) was developed to protect Jefferson Labs transport lines, targets and beam dumps from a catastrophic ''burn through''. Range changes and testing was accomplished manually requiring the experiment to be shut down. The new upgraded system is based around an ''off the shelf'' Programmable Logic Controller located in a single control box supporting up to ten individual detectors. All functions that formerly required an entry into the experimental hall and manual adjustment can be accomplished from the Machine Control Center (MCC). A further innovation was the addition of a High Voltage ''Brick'' at the detector location. A single cable supplies the required voltage for the Brick and a return line for the ion chamber signal. The read back screens display range, trip point, and accumulated dose for each location. The new system is very cost effective and significantly reduces the amount of lost experimental time.

  6. Commissioning of a large segmented ion chamber for the FMA

    SciTech Connect

    Lister, C.J.; Davids, C.N.; Blumenthal, D.J.

    1995-08-01

    A large-area sectored ion chamber was built by a Yale-Daresbury (U.K.) - ANL collaboration to allow extensions of studies of N = Z (T = 0) nuclei. The ion chamber is a conventional DE-DE-E detector which is 20-cm deep, but each anode is segmented into eight pads to allow high count-rate capability and ray-trace reconstruction. With suitable electronics, the detector can become eight close-packed ion chambers, considerably reducing the count rate in each. A position-wire plane allows further raytracing which should permit the rejection of anomalous trajectories and improve Z-separation. A brief test run was scheduled shortly after delivery. Performance appeared promising, but issues of gain matching and cross talk need further exploration. We will study these features {open_quotes}off line{close_quotes} and hope to perform a full experiment on selenium isotopes in the summer. This detector appears to have many uses and is potentially more useful than previous detectors of its type. Similar detectors are being built for the HHRF at Oak Ridge and for Texas A&M University.

  7. Monte Carlo calculations of electron beam quality conversion factors for several ion chamber types

    SciTech Connect

    Muir, B. R.; Rogers, D. W. O.

    2014-11-01

    Purpose: To provide a comprehensive investigation of electron beam reference dosimetry using Monte Carlo simulations of the response of 10 plane-parallel and 18 cylindrical ion chamber types. Specific emphasis is placed on the determination of the optimal shift of the chambers’ effective point of measurement (EPOM) and beam quality conversion factors. Methods: The EGSnrc system is used for calculations of the absorbed dose to gas in ion chamber models and the absorbed dose to water as a function of depth in a water phantom on which cobalt-60 and several electron beam source models are incident. The optimal EPOM shifts of the ion chambers are determined by comparing calculations of R{sub 50} converted from I{sub 50} (calculated using ion chamber simulations in phantom) to R{sub 50} calculated using simulations of the absorbed dose to water vs depth in water. Beam quality conversion factors are determined as the calculated ratio of the absorbed dose to water to the absorbed dose to air in the ion chamber at the reference depth in a cobalt-60 beam to that in electron beams. Results: For most plane-parallel chambers, the optimal EPOM shift is inside of the active cavity but different from the shift determined with water-equivalent scaling of the front window of the chamber. These optimal shifts for plane-parallel chambers also reduce the scatter of beam quality conversion factors, k{sub Q}, as a function of R{sub 50}. The optimal shift of cylindrical chambers is found to be less than the 0.5 r{sub cav} recommended by current dosimetry protocols. In most cases, the values of the optimal shift are close to 0.3 r{sub cav}. Values of k{sub ecal} are calculated and compared to those from the TG-51 protocol and differences are explained using accurate individual correction factors for a subset of ion chambers investigated. High-precision fits to beam quality conversion factors normalized to unity in a beam with R{sub 50} = 7.5 cm (k{sub Q}{sup ′}) are provided. These

  8. Characterization of a multi-axis ion chamber array

    SciTech Connect

    Simon, Thomas A.; Kozelka, Jakub; Simon, William E.; Kahler, Darren; Li, Jonathan; Liu, Chihray

    2010-11-15

    Purpose: The aim of this work was to characterize a multi-axis ion chamber array (IC PROFILER; Sun Nuclear Corporation, Melbourne, FL USA) that has the potential to simplify the acquisition of LINAC beam data. Methods: The IC PROFILER (or panel) measurement response was characterized with respect to radiation beam properties, including dose, dose per pulse, pulse rate frequency (PRF), and energy. Panel properties were also studied, including detector-calibration stability, power-on time, backscatter dependence, and the panel's agreement with water tank measurements [profiles, fractional depth dose (FDD), and output factors]. Results: The panel's relative deviation was typically within ({+-}) 1% of an independent (or nominal) response for all properties that were tested. Notable results were (a) a detectable relative field shape change of {approx}1% with linear accelerator PRF changes; (b) a large range in backscatter thickness had a minimal effect on the measured dose distribution (typically less than 1%); (c) the error spread in profile comparison between the panel and scanning water tank (Blue Phantom, CC13; IBA Schwarzenbruck, DE) was approximately ({+-}) 0.75%. Conclusions: The ability of the panel to accurately reproduce water tank profiles, FDDs, and output factors is an indication of its abilities as a dosimetry system. The benefits of using the panel versus a scanning water tank are less setup time and less error susceptibility. The same measurements (including device setup and breakdown) for both systems took 180 min with the water tank versus 30 min with the panel. The time-savings increase as the measurement load is increased.

  9. MEASUREMENT OF SURFACE ALPHA CONTAMINATION USING ELECTRET ION CHAMBERS

    SciTech Connect

    M.A. Ebadian, Ph.D.

    1999-01-01

    Electret ion chambers (EICs) are known to be inexpensive, reliable, passive, integrating devices used for measurement of ionizing radiation. Their application for measurement of alpha contamination on surfaces was recently realized. This two-year project deals with the evaluation of electret ion chambers with different types of electrets and chambers for measurement of surface alpha contamination, their demonstration at U.S. Department of Energy (DOE) sites, a cost-benefit comparison with the existing methods, and the potential deployment at DOE sites. During the first year (FY98) of the project, evaluation of the EICS was completed. It was observed that EICS could be used for measurement of free release level of alpha contamination for transuranics (100 dpm/100 cm{sup 2} fixed). DOE sites, where demonstration of EIC technology for surface alpha contamination measurements could be performed, were also identified. During FY99, demonstration and deployment of EICS at DOE sites are planned. A cost-benefit analysis of the EIC for surface alpha contamination measurement will also be performed.

  10. Paired Ion Chamber Constants for Fission Gamma-Neutron Fields

    DTIC Science & Technology

    1984-12-01

    energy E. For neutrons with energies distributed over a spectrum, the above theory must be extended to define a spectrum-averaged neutron W-value...733, 1979. 21. DLC-31/(DPL-1/FEWG1), 37- neutrOn , 21-gamma ray coupled, P3, multigroup library in ANISN Format. ORNL/TM-4840. Oak Ridge National...ragMD©/^ ^i[p@^¥ Paired ion chamber constants for fission gamma- neutron fields G. H.Zeman K. P. Ferlic DEFENSE NUCLEAR AGENCY ARMED FORCES

  11. Long ion chamber systems for the SLC (Stanford Linear Collider)

    SciTech Connect

    Rolfe, J.; Gearhart, R.; Jacobsen, R.; Jenkins, T.; McComick, D.; Nelson, R.; Reagan, D.; Ross, M.

    1989-03-01

    A Panofsky Long Ion Chamber (PLIC) is essentially a gas-filled coaxial cable, and has been used to protect the Stanford Linear Accelerator from damage caused by its electron beam, and as a sensitive diagnostic tool. This old technology has been updated and has found renewed use in the SLC. PLIC systems have been installed as beam steering aids in most parts of the SLC and are a part of the system that protects the SLC from damage by errant beams in several places. 5 refs., 3 figs., 1 tab.

  12. Plasma generation near an Ion thruster disharge chamber hollow cathode

    NASA Technical Reports Server (NTRS)

    Katz, Ira; Anderson, John R.; Goebel, Dan M.; Wirz, Richard; Sengupta, Anita

    2003-01-01

    In gridded electrostatic thrusters, ions are produced by electron bombardment in the discharge chamber. In most of these thrusters, a single, centrally located hollow cathode supplies the ionizing electrons. An applied magnetic field in the discharge chamber restricts the electrons leaving the hollow cathode to a very narrow channel. In this channel, the high electron current density ionizes both propellant gas flowing from the hollow cathode, and other neutrals from the main propellant flow from the plenum. The processes that occur just past the hollow cathode exit are very important. In recent engine tests, several cases of discharge cathode orifice place and keeper erosion have been reported. In this paper we present results from a new 1-D, variable area model of the plasma processes in the magnetized channel just downstream of the hollow cathode keeper. The model predicts plasma densities, and temperatures consistent with those reported in the literature for the NSTAR engine, and preliminary results from the model show a potential maximum just downstream of the cathode.

  13. Extraction characteristics of a low-energy ion beam system with a remote plasma chamber

    SciTech Connect

    Vasquez, M. R.; Wada, M.

    2016-02-15

    Low-energy argon beams were extracted from a dual-chamber ion source system. The first chamber is a quartz cylinder where dense inductively coupled plasmas were produced using 13.56 MHz radio frequency (rf) power. The discharge was driven into an adjacent chamber which acts as a reservoir for ion beam extraction using a dual-electrode extractor configuration. Extraction of ions from the second chamber with energies in the 100 eV range was achieved while minimizing fluctuations induced by the rf signal. A custom-built retarding potential analyzer was used to analyze the effectiveness of ion beam transport using the remote plasma chamber. Well-defined beams were extracted between 60 and 100 V extraction potentials at 50–100 W rf powers. An increase in rf power resulted in an increase in average ion energy, increase in ion current density while the energy spread remains constant.

  14. Development of a novel reaction chamber for ion beam analysis of large samples

    NASA Astrophysics Data System (ADS)

    Kakuee, O. R.; Fathollahi, V.; Agha-Aligol, D.; Farmahini-Farahani, M.; Oliaiy, P.; Lamehi-Rachti, M.

    2008-04-01

    A novel vacuum chamber for ion beam analysis of large-size industrial samples - whose analysis are not feasible in conventional ion beam analysis reaction chambers - has been designed, fabricated and successfully tested. Using the newly developed chamber, both PIXE and RBS analyses could be carried out at the same time and on the same point of the samples. Ion beam analysis using this novel chamber lacks the disadvantages of external beam analysis and benefits the advantages of in-vacuum analysis. This has been achieved by designing a tiny open port in the wall of the reaction chamber to be sealed with a small flat area of sample body where its analysis is of interest. As a case study, two samples of gas turbine blades, a corroded one at highly corrosive environment and a refurbished one after application of certain coatings are analysed using the novel chamber. Experimental results confirm the performance and capability of the reaction chamber.

  15. A Current Mode Ion Chamber for the n+p->D+gamma Parity Violation Experiment

    NASA Astrophysics Data System (ADS)

    Snow, William

    2001-04-01

    We have developed and tested a current-mode 3He-based ion chamber for the measurement of the neutron time-of-flight spectrum from a pulsed cold neutron source on a pulse-by-pulse basis. Such a device is required in the n+p->D+gamma experiment for general diagnostic purposes and for monitoring the ortho-para ratio in the liquid hydrogen target by neutron transmission. This detector was tested in the fall of 2000 at the LANSCE pulsed cold neutron source. The chamber operates with a mixture gas of 0.5 atm 3He and 3 atm H2 and possesses segmentation along the neutron beam. The design is similar to that of Penn et al [1] which was used for a neutron-4He parity violation experiment, but with modifications to the time response and the dynamic range in neutron energy required for operation at a pulsed neutron source. The relevant technical characteristics of the ion chamber (time response, sensitivity to Mev gammas, noise, efficiency, neutron energy dynamic range, linearity) will be described. [1] S. Penn et.al., submitted to NIM (2000)

  16. Post-flight Analysis of the Argon Filled Ion Chamber

    NASA Technical Reports Server (NTRS)

    Tai, H.; Goldhagen, P.; Jones, I. W.; Wilson, J. W.; Maiden, D. L.; Shinn, J. L.

    2003-01-01

    Atmospheric ionizing radiation is a complex mixture of primary galactic and solar cosmic rays and a multitude of secondary particles produced in collision with air nuclei. The first series of Atmospheric Ionizing Radiation (AIR) measurement flights on the NASA research aircraft ER-2 took place in June 1997. The ER-2 flight package consisted of fifteen instruments from six countries and were chosen to provide varying sensitivity to specific components. These AIR ER-2 flight measurements are to characterize the AIR environment during solar minimum to allow the continued development of environmental models of this complex mixture of ionizing radiation. This will enable scientists to study the ionizing radiation health hazard associated with the high-altitude operation of a commercial supersonic transport and to allow estimates of single event upsets for advanced avionics systems design. The argon filled ion chamber representing about 40 percent of the contributions to radiation risks are analyzed herein and model discrepancies for solar minimum environment are on the order of 5 percent and less. Other biologically significant components remain to be analyzed.

  17. Ion-chamber-based loss monitor system for the Los Alamos Meson Physics Facility

    SciTech Connect

    Plum, M.A.; Brown, D.; Browman, A.; Macek, R.J.

    1995-05-01

    A new loss monitor system has been designed and installed at the Los Alamos Meson Physics Facility (LAMPF). The detectors are ion chambers filled with N{sub 2} gas. The electronics modules have a threshold range of 1:100, and they can resolve changes in beam loss of about 2% of the threshold settings. They can generate a trip signal in 2 {mu}s if the beam loss is large enough; if the response time of the Fast Protect System is included the beam will be shut off in about 37 {mu}s.

  18. Improved diffusion chamber cultures for cytokinetic analysis of antibody response

    PubMed Central

    Nettesheim, P.; Makinodan, T.; Chadwick, Carol J.

    1966-01-01

    Diffusion chambers (3×10 mm) constructed with 0.1 μ porosity filters, but not with 0.45 μ or greater porosity filters, were found to be consistently cell impermeable, with use of acryloid as the glueing agent. The filters permit free diffusion of 19S and 7S antibodies into `empty' chambers in vivo and in vitro. Pronase treatment of the chamber dissolves the clot and frees cells attached to the inner surfaces. This permits almost complete recovery of the chamber culture cells. Chamber cultures can be readily transferred from one host to another and kept in vitro at room temperature for at least 6 hours without any loss of activity. In vivo diffusion problems arise after 1 month of culture, most probably due to excessive growth of peritoneal cells on the outer surface of the filters; this limitation can be overcome by serial in vivo transfer of the chamber and wiping the outer surface at the time of transfer. The diffusion chamber culture method as described here fulfills all the prerequisites of an assay system with which one can perform precise cytokinetic analysis of antibody response. ImagesFIG. 3 PMID:5926065

  19. An experimental and computational investigation of the standard temperature-pressure correction factor for ion chambers in kilovoltage x rays.

    PubMed

    La Russa, Daniel J; McEwen, Malcolm; Rogers, D W O

    2007-12-01

    For ion chambers with cavities open to the surrounding atmosphere, the response measured at a given temperature and pressure must be corrected using the standard temperature-pressure correction factor (P(TP)). A previous paper based solely on Monte Carlo simulations [D. J. La Russa and D. W. O. Rogers, Med. Phys. 33, 4590-4599 (2006)] pointed out the shortcomings of the P(TP) correction factor when used to correct the response of non-air-equivalent chambers for low-energy x-ray beams. This work presents the results of several experiments that corroborate these calculations for a number of ion chambers. Monte Carlo simulations of the experimental setup revealed additional insight into the various factors affecting the extent of the breakdown of P(TP), including the effect of impurities and the sensitivity to chamber dimensions. For an unfiltered 60 kV beam, the P(TP)-corrected response of an NE 2571 ion chamber measured at 0.7 atm was 2.5% below the response measured at reference conditions. In general, Monte Carlo simulations of the experimental setup using EGSnrc were within 0.5% of measured values. EGSnrc-calculated values of air kerma calibration coefficients (N(K)) at low x-ray energies are also provided as a means of estimating the level of impurities in the chambers investigated. Calculated values of N(K) normalized to the value measured for a 250 kV beam were obtained for three chambers and were within 1% of experiment with one exception, the Exradin A12 in a 50 kV beam.

  20. Dose verification with different ion chambers for SRT/SBRT plans

    NASA Astrophysics Data System (ADS)

    Durmus, I. F.; Tas, B.; Okumus, A.; Uzel, O. E.

    2017-02-01

    Verification of patient plan is very important in stereotactic treatments. VMAT plans were prepared with 6MV-FFF or 10MV-FFF energies for 25 intracranial and extracranial stereotactic patients. Absolute dose was measured for dose verification in each plans. Iba® CC01, Iba® CC04, Iba® CC13 ion chambers placed at a depth of 5cm in solid phantom (RW3). Also we scanned this phantom with ion chambers by Siemens® Biograph mCT. QA plans were prepared by transferring twenty five patient plans to phantom assemblies for three ion chambers. All plans were performed separately for three ion chambers at Elekta® Versa HD linear accelerator. Statistical analysis of results were made by Wilcoxon signed-rank test. Difference between dose values were determined %1.84±3.4 (p: 0.001) with Iba CC13 ion chamber, %1.80±3.4 (p: 0.002) with Iba CC04 ion chamber and %0.29±4.6 (p: 0.667) with Iba CC01 ion chamber. In stereotactic treatments, dosimetric uncertainty increases in small areas. We determined more accurate results with small sized detectors. Difference between TPS calculations and all measurements were founded lower than %2.

  1. High-intensity positive beams extracted from a compact double-chamber ion source

    SciTech Connect

    Huck, H.; Somacal, H.; Di Gregorio, D.E.; Fernandez Niello, J.O.; Igarzabal, M.; Di Paolo, H.; Reinoso, M.

    2005-06-15

    This work presents the design and development of a simple ion source, the associated ion extraction optics, and the beam transport of a low-energy and high-current proton accelerator. In its actual version, the ion source can deliver positive proton currents up to 100 mA. This rather high beam current is achieved by adding a small ionization chamber between the discharge chamber containing the filament and the extraction electrode of the ion source. Different parameters of the ion source and the injection beam line are evaluated by means of computer simulations to optimize the beam production and transmission.

  2. An Egsnrc investigation of the P(TP) correction factor for ion chambers in kilovoltage X rays.

    PubMed

    La Russa, Daniel J; Rogers, D W O

    2006-12-01

    As part of the standard practice for obtaining consistent ion chamber measurements with cavities open to the surrounding atmosphere, the raw measured response is corrected to the response at a reference temperature and pressure using the standard temperature-pressure correction factor (P(TP)). In this study, the EGSnrc Monte Carlo code was used to investigate the validity of the P(TP) correction factor for kilovoltage x rays incident on various geometrically distinct ion chambers. The calculated P(TP)-corrected chamber response deviated by over 2% relative to expected values for a 40 kV spectrum incident on a graphite thimble chamber at an air density typical of Mexico City. The relative deviation from the expected response was much worse for a large spherical graphite chamber, exceeding 16% at an air density of 0.6 kg/m3 (approximately 0.5 atm at 22 degrees C) for the same beam energy. The breakdown of the P(TP) correction factor was also observed for a 26 kV mammography spectrum incident on two mammography chambers. For 60Co beams, the P(TP) correction factor behaved as expected. For day-to-day variations in pressure, only a negligible of the P(TP) correction factor was observed with low x-ray energies. Factors contributing to the breakdown of the P(TP) correction factor at low x-ray energies and large pressure variations, such as the range of electrons, the material of the wall, the chamber dimensions and air-photon interactions, are discussed in depth.

  3. Determination of relative ion chamber calibration coefficients from depth-ionization measurements in clinical electron beams

    NASA Astrophysics Data System (ADS)

    Muir, B. R.; McEwen, M. R.; Rogers, D. W. O.

    2014-10-01

    A method is presented to obtain ion chamber calibration coefficients relative to secondary standard reference chambers in electron beams using depth-ionization measurements. Results are obtained as a function of depth and average electron energy at depth in 4, 8, 12 and 18 MeV electron beams from the NRC Elekta Precise linac. The PTW Roos, Scanditronix NACP-02, PTW Advanced Markus and NE 2571 ion chambers are investigated. The challenges and limitations of the method are discussed. The proposed method produces useful data at shallow depths. At depths past the reference depth, small shifts in positioning or drifts in the incident beam energy affect the results, thereby providing a built-in test of incident electron energy drifts and/or chamber set-up. Polarity corrections for ion chambers as a function of average electron energy at depth agree with literature data. The proposed method produces results consistent with those obtained using the conventional calibration procedure while gaining much more information about the behavior of the ion chamber with similar data acquisition time. Measurement uncertainties in calibration coefficients obtained with this method are estimated to be less than 0.5%. These results open up the possibility of using depth-ionization measurements to yield chamber ratios which may be suitable for primary standards-level dissemination.

  4. A method to enhance 2D ion chamber array patient specific quality assurance for IMRT.

    PubMed

    Diaz Moreno, Rogelio Manuel; Venencia, Daniel; Garrigo, Edgardo; Pipman, Yakov

    2016-11-21

    Gamma index comparison has been established as a method for patient specific quality assurance in IMRT. Detector arrays can replace radiographic film systems to record 2D dose distributions and fulfill quality assurance requirements. These electronic devices present spatial resolution disadvantages with respect to films. This handicap can be partially overcome with a multiple acquisition sequence of adjacent 2D dose distributions. The detector spatial response influence can also be taken into account through the convolution of the calculated dose with the detector spatial response. A methodology that employs both approaches could allow for enhancements of the quality assurance procedure. 35 beams from different step and shoot IMRT plans were delivered on a phantom. 2D dose distributions were recorded with a PTW-729 ion chamber array for individual beams, following the multiple acquisition methodology. 2D dose distributions were also recorded on radiographic films. Measured dose distributions with films and with the PTW-729 array were processed with the software RITv5.2 for Gamma index comparison with calculated doses. Calculated dose was also convolved with the ion chamber 2D response and the Gamma index comparisons with the 2D dose distribution measured with the PTW-729 array was repeated. 3.7 ± 2.7% of points surpassed the accepted Gamma index when using radiographic films compared with calculated dose, with a minimum of 0.67 and a maximum of 13.27. With the PTW-729 multiple acquisition methodology compared with calculated dose, 4.1 ± 1.3% of points surpassed the accepted Gamma index, with a minimum of 1.44 and a maximum of 11.26. With the PTW- multiple acquisition methodology compared with convolved calculated dose, 2.7 ± 1.3% of points surpassed the accepted Gamma index, with a minimum of 0.42 and a maximum of 5.75. The results obtained in this work suggest that the comparison of merged adjacent dose distributions with convolved calculated dose

  5. Heavy ion beam studies and imaging with a multiplane multiwire proportional chamber

    SciTech Connect

    Chu, W.T.; Alonso, J.R.; Tobias, C.A.

    1981-03-01

    A 16-plane multiwire proportional chamber is used to accurately measure intensity profiles of heavy ion beams at the Bevalac. An imaging capability has now been developed for the system, allowing for reconstruction of 3-dimensional representation of radiological objects using heavy ion beams.

  6. Imaging with a multiplane multiwire proportional chamber using heavy ion beams

    SciTech Connect

    Chu, W.T.; Alonso, J.R.; Tobias, C.A.

    1982-01-01

    A 16-plane multiwire proportional chamber has been developed to accurately map intensity profiles of heavy ion beams at the Bevalac. The imaging capability of the system has been tested for reconstruction of 3-dimensional representation of a canine thorax region using heavy ion beams.

  7. Shielding analysis for a heavy ion beam chamber with plasma channels for ion transport

    SciTech Connect

    Sawan, M.E.; Peterson, R.R.; Yu, S.

    2000-06-28

    Neutronics analysis has been performed to assess the shielding requirements for the insulators and final focusing magnets in a modified HYLIFE-II target chamber that utilizes pre-formed plasma channels for heavy ion beam transport. Using 65 cm thick Flibe jet assemblies provides adequate shielding for the electrical insulator units. Additional shielding is needed in front of the final focusing superconducting quadrupole magnets. A shield with a thickness varying between 45 and 90 cm needs to be provided in front of the quadrupole unit. The final laser mirrors located along the channel axis are in the direct line-of-sight of source neutrons. Neutronics calculations were performed to determine the constraints on the placement of these mirrors to be lifetime components.

  8. Estimation of absorbed dose in clinical radiotherapy linear accelerator beams: Effect of ion chamber calibration and long-term stability.

    PubMed

    Ravichandran, Ramamoorthy; Binukumar, Johnson Pichy; Davis, Cheriyathmanjiyil Antony

    2013-10-01

    The measured dose in water at reference point in phantom is a primary parameter for planning the treatment monitor units (MU); both in conventional and intensity modulated/image guided treatments. Traceability of dose accuracy therefore still depends mainly on the calibration factor of the ion chamber/dosimeter provided by the accredited Secondary Standard Dosimetry Laboratories (SSDLs), under International Atomic Energy Agency (IAEA) network of laboratories. The data related to Nd,water calibrations, thermoluminescent dosimetry (TLD) postal dose validation, inter-comparison of different dosimeter/electrometers, and validity of Nd,water calibrations obtained from different calibration laboratories were analyzed to find out the extent of accuracy achievable. Nd,w factors in Gray/Coulomb calibrated at IBA, GmBH, Germany showed a mean variation of about 0.2% increase per year in three Farmer chambers, in three subsequent calibrations. Another ion chamber calibrated in different accredited laboratory (PTW, Germany) showed consistent Nd,w for 9 years period. The Strontium-90 beta check source response indicated long-term stability of the ion chambers within 1% for three chambers. Results of IAEA postal TL "dose intercomparison" for three photon beams, 6 MV (two) and 15 MV (one), agreed well within our reported doses, with mean deviation of 0.03% (SD 0.87%) (n = 9). All the chamber/electrometer calibrated by a single SSDL realized absorbed doses in water within 0.13% standard deviations. However, about 1-2% differences in absorbed dose estimates observed when dosimeters calibrated from different calibration laboratories are compared in solid phantoms. Our data therefore imply that the dosimetry level maintained for clinical use of linear accelerator photon beams are within recommended levels of accuracy, and uncertainties are within reported values.

  9. Convert Ten Foot Environmental Test Chamber into an Ion Engine Test Chamber

    NASA Technical Reports Server (NTRS)

    VanVelzer, Paul

    2006-01-01

    The 10 Foot Space Simulator at the Jet Propulsion Laboratory has been used for the last 40 years to test numerous spacecraft, including the Ranger series, several Mariner class, among many others and finally, the Spirit and Opportunity Mars Rovers. The request was made to convert this facility to an Ion Engine test facility, with a possible long term life test. The Ion engine was to propel the Prometheus spacecraft to Jupiter's moons. This paper discusses the challenges that were met, both from a procedural and physical standpoint. The converted facility must operate unattended, support a 30 Kw Ion Engine, operate economically, and be easily converted back to former operation as a spacecraft test facility.

  10. Impact of beam transport method on chamber and driver design for heavy ion inertial fusion energy

    SciTech Connect

    Rose, D.V.; Welch, D.R.; Olson, C.L.; Yu, S.S.; Neff, S.; Sharp, W.M.

    2002-12-01

    In heavy ion inertial fusion energy systems, intense beams of ions must be transported from the exit of the final focus magnet system through the target chamber to hit millimeter spot sizes on the target. In this paper, we examine three different modes of beam propagation: neutralized ballistic transport, assisted pinched transport, and self-pinched transport. The status of our understanding of these three modes is summarized, and the constraints imposed by beam propagation upon the chamber environment, as well as their compatibility with various chamber and target concepts, are considered. We conclude that, on the basis of our present understanding, there is a reasonable range of parameter space where beams can propagate in thick-liquid wall, wetted-wall, and dry-wall chambers.

  11. Computational Model Tracking Primary Electrons, Secondary Electrons, and Ions in the Discharge Chamber of an Ion Engine

    NASA Technical Reports Server (NTRS)

    Mahalingam, Sudhakar; Menart, James A.

    2005-01-01

    Computational modeling of the plasma located in the discharge chamber of an ion engine is an important activity so that the development and design of the next generation of ion engines may be enhanced. In this work a computational tool called XOOPIC is used to model the primary electrons, secondary electrons, and ions inside the discharge chamber. The details of this computational tool are discussed in this paper. Preliminary results from XOOPIC are presented. The results presented include particle number density distributions for the primary electrons, the secondary electrons, and the ions. In addition the total number of a particular particle in the discharge chamber as a function of time, electric potential maps and magnetic field maps are presented. A primary electron number density plot from PRIMA is given in this paper so that the results of XOOPIC can be compared to it. PRIMA is a computer code that the present investigators have used in much of their previous work that provides results that compare well to experimental results. PRIMA only models the primary electrons in the discharge chamber. Modeling ions and secondary electrons, as well as the primary electrons, will greatly increase our ability to predict different characteristics of the plasma discharge used in an ion engine.

  12. SU-E-T-198: Comparison Between a PTW MicroDiamond Dosimeter and a Markus Chamber in a 62 MeV/n Carbon Ion Beam

    SciTech Connect

    Rossomme, S; Hopfgartner, J; Delor, A; Vynckier, S; Palmans, H

    2015-06-15

    Purpose: To investigate the linear energy transfer (LET) dependence of a PTW Freiburg microDiamond dosimeter, we compared its response to the response of a plane-parallel Markus chamber in a 62 MeV/n mono-energetic carbon ion beam. Methods: The response of both detectors has been studied as a function of depth in graphite by adding or removing graphite plates in front of the detectors. To account for fluctuations of the beam, we used two setups with different monitor chambers. The depth of the effective point of measurement of both detectors has been converted into a graphite equivalent depth using ICRU Report 73 data. As recommended by IAEA TRS-398, the response of the Markus chamber has been corrected for temperature, pressure, polarity effects and ion recombination. The latter required an additional experiment; to quantify the effect of volume recombination and initial recombination, measurements have been performed at different voltages and different dose rates. Results: As expected, the dominant process leading to ion recombination for carbon ion beam is the initial recombination. At the entrance, the ion recombination correction equals 1.1% and the value is approximately constant in the plateau region. Due to the increase of the LET in the Bragg peak region, we observe a strong increase of the ion recombination correction, up to 6.1% at the distal edge. Comparison between the microDiamond response and the Markus chamber response shows good agreement in the plateau region. However, we observe a 13.6% under response of the microDiamond in the Bragg peak. Conclusion: Increasing between 1% and 6%, the depth dependent ion recombination correction has to be applied to the Markus response. The comparison between the microDiamond and the Markus chamber indicates that there is an under-response of the microDiamond in the vicinity of the Bragg peak due to the increased LET.

  13. Distributed drift chamber design for rare particle detection in relativistic heavy ion collisions

    SciTech Connect

    Bellwied, R.; Bennett, M.J.; Bernardo, V.; Caines, H.; Christie, W.; Costa, S.; Crawford, H.J.; Cronqvist, M.; Debbe, R.; Dinnwiddie, R.; Engelage, J.; Flores, I.; Fuzesy, R.; Greiner, L.; Hallman, T.; Hoffmann, G.; Huang, H.Z.; Jensen, P.; Judd, E.G.; Kainz, K.; Kaplan, M.; Kelly, S.; Lindstrom, P.J; Llope, W.J.; LoCurto, G.; Longacre, R.; Milosevich, Z.; Mitchell, J.T.; Mitchell, J.W.; Mogavero, E.; Mutchler, G.; Paganis, S.; Platner, E.; Potenza, R.; Rotondo, F.; Russ, D.; Sakrejda, I.; Saulys, A.; Schambach, J.; Sheen, J.; Smirnoff, N.; Stokeley, C.; Tang, J.; Trattner, A.L.; Trentalange, S.; Visser, G.; Whitfield, J.P.; Witharm, F.; Witharm, R.; Wright, M.

    2001-10-02

    This report describes a multi-plane drift chamber that was designed and constructed to function as a topological detector for the BNL AGSE896 rare particle experiment. The chamber was optimized for good spatial resolution, two track separation, and a high uniform efficiency while operating in a 1.6 Tesla magnetic field and subjected to long term exposure from a 11.6 GeV/nucleon beam of 10**6 Au ions per second.

  14. Retention of Sputtered Molybdenum on Ion Engine Discharge Chamber Surfaces

    NASA Technical Reports Server (NTRS)

    Sovey, James S.; Dever, Joyce A.; Power, John L.

    2001-01-01

    Grit-blasted anode surfaces are commonly used in ion engines to ensure adherence of sputtered coatings. Next generation ion engines will require higher power levels, longer operating times, and thus there will likely be thicker sputtered coatings on their anode surfaces than observed to date on 2.3 kW-class xenon ion engines. The thickness of coatings on the anode of a 10 kW, 40-centimeter diameter thruster, for example, may be 22 micrometers or more after extended operation. Grit-blasted wire mesh, titanium, and aluminum coupons were coated with molybdenum at accelerated rates to establish coating stability after the deposition process and after thermal cycling tests. These accelerated deposition rates are roughly three orders of magnitude more rapid than the rates at which the screen grid is sputtered in a 2.3 kW-class, 30-centimeter diameter ion engine. Using both RF and DC sputtering processes, the molybdenum coating thicknesses ranged from 8 to 130 micrometers, and deposition rates from 1.8 micrometers per hour to 5.1 micrometers per hour. In all cases, the molybdenum coatings were stable after the deposition process, and there was no evidence of spalling of the coatings after 20 cycles from about -60 to +320 C. The stable, 130 micrometer molybdenum coating on wire mesh is 26 times thicker than the thickest coating found on the anode of a 2.3 kW, xenon ion engine that was tested for 8200 hr. Additionally, this coating on wire mesh coupon is estimated to be a factor of greater than 4 thicker than one would expect to obtain on the anode of the next generation ion engine which may have xenon throughputs as high as 550 kg.

  15. Efficiency improvements for ion chamber calculations in high energy photon beams

    SciTech Connect

    Wulff, J.; Zink, K.; Kawrakow, I.

    2008-04-15

    This article presents the implementation of several variance reduction techniques that dramatically improve the simulation efficiency of ion chamber dose and perturbation factor calculations. The cavity user code for the EGSnrc Monte Carlo code system is extended by photon cross-section enhancement (XCSE), an intermediate phase-space storage (IPSS) technique, and a correlated sampling (CS) scheme. XCSE increases the density of photon interaction sites inside and in the vicinity of the chamber and results - in combination with a Russian Roulette game for electrons that cannot reach the cavity volume - in an increased efficiency of up to a factor of 350 for calculating dose in a Farmer type chamber placed at 10 cm depth in a water phantom. In combination with the IPSS and CS techniques, the efficiency for the calculation of the central electrode perturbation factor P{sub cel} can be increased by up to three orders of magnitude for a single chamber location and by nearly four orders of magnitude when considering the P{sub cel} variation with depth or with distance from the central axis in a large field photon beam. The intermediate storage of the phase-space properties of particles entering a volume that contains many possible chamber locations leads to efficiency improvements by a factor larger than 500 when computing a profile of chamber doses in the field of a linear accelerator photon beam. All techniques are combined in a new EGSnrc user code egs{sub c}hamber. Optimum settings for the variance reduction parameters are investigated and are reported for a Farmer type ion chamber. A few example calculations illustrating the capabilities of the egs{sub c}hamber code are presented.

  16. Comparison of dose measurements in CT using a novel semiconductor detector and a small ion chamber

    SciTech Connect

    Paschoal, Cinthia M. M.; Ferreira, Fernanda Carla L.; Santos, Luiz A. P.; Souza, Divanizia N.

    2015-07-01

    The advance of multislice computed tomography (CT) has become inadequate the currently dosimetric protocol used in CT. Instead of dosimetry based on the measurement of CTDI using a pencil ion chamber of 100 m of length, it was proposed the use of a small ion chamber (IC) and the calculating the dose equilibrium (Deq) at the location of the chamber. The objective of this work was to compare the performance of a short IC and a commercial photodiode to measure the accumulated dose at the center of the scan length L, DL(0), and to obtain the equilibrium dose Deq using the two detectors. The result for L=100 mm was compared with the result of a pencil chamber. The results indicate that the commercial photodiode is suitable to measure the accumulated dose at the center of the scan length L as compared with the ion chambers. This methodology allows measurements of the accumulated dose for any desired scan length, allowing measuring the equilibrium dose Deq if the phantom is long enough to allow it. (authors)

  17. High-resolution ion pulse ionization chamber with air filling for the 222Rn decays detection

    NASA Astrophysics Data System (ADS)

    Gavrilyuk, Yu. M.; Gangapshev, A. M.; Gezhaev, A. M.; Etezov, R. A.; Kazalov, V. V.; Kuzminov, V. V.; Panasenko, S. I.; Ratkevich, S. S.; Tekueva, D. A.; Yakimenko, S. P.

    2015-11-01

    The construction and characteristics of the cylindrical ion pulse ionization chamber (CIPIC) with a working volume of 3.2 L are described. The chamber is intended to register α-particles from the 222Rn and its daughter's decays in the filled air sample. The detector is less sensitive to electromagnetic pick-ups and mechanical noises. The digital pulse processing method is proposed to improve the energy resolution of the ion pulse ionization chamber. An energy resolution of 1.6% has been achieved for the 5.49 MeV α-line. The dependence of the energy resolution on high voltage and working media pressure has been investigated and the results are presented.

  18. SU-E-T-172: Evaluation of the Exradin A26 Ion Chamber in Megavoltage Photon Beams as a Reference Class Instrument

    SciTech Connect

    McEwen, M

    2014-06-01

    Purpose: The Exradin A26 is a new design of micro-ionization ion chamber that externally resembles the Exradin A16 model but has significant internal changes to address measurement issues reported in the literature for the A16. This project involved the characterization of two versions of the A26 chamber in high energy x-rays with particular reference to the performance specification laid out in the imminent Addendum to TG-51. Methods: The Exradin A26 was investigated in a range of megavoltage photon beams (6–25 MV). Investigations looked at chamber settling, ion recombination and polarity. Since it has been previously shown that non-ideal performance is most easily identified through ion recombination measurements, the focus was on the determination of Pion. Results: i) Chamber settling - the chamber response stabilizes very quickly (within 3 minutes), even after a large change in the polarizing voltage.ii) The polarity correction was found to be small (within 0.2% of unity)iii) The chamber showed linear behavior for a Jaffe plot (1/reading vs 1/polarizing voltage) for applied voltages ≤ 200 V.iv) The recombination correction showed a linear variation with the doseper- pulse, was not significantly dependent on the polarity of the collecting voltage and was consistent with the chamber dimensions (i.e. agreed with Boag theory). Conclusion: An initial investigation of the Exradin A26 micro chamber suggests that although its performance exceeds the AAPM specification for a reference-class ion chamber for use in megavoltage photon beams it is a significant improvement over the previous A16 design. Further work is required to evaluate long-term stability and determine kQ factors.

  19. Plasma Emission Characteristics From a High Current Hollow Cathode in an Ion Thruster Discharge Chamber

    NASA Astrophysics Data System (ADS)

    Foster, John E.; Patterson, Michael J.

    2002-11-01

    The presence of energetic ions produced by a hollow cathodes operating at high emission currents (greater than 5A) has been documented in the literature. In order to further elucidate these findings, an investigation of a high current cathode operating in an ion thruster discharge chamber has been undertaken. Using Langmuir probes, a low energy charged particle analyzer and emission spectroscopy, the behavior of the near-cathode plasma and the emitted ion energy distribution was characterized. The presence of energetic ions was confirmed. It was observed that these ions had energies in excess of the discharge voltage and thus cannot be simply explained by ions falling out of plasma through a potential difference of this order. Additionally, evidence provided by Langmuir probes suggests the existence of a double layer essentially separating the hollow cathode plasma column from the main discharge. The radial potential difference associated with this double layer was measured to be of order the ionization potential.

  20. Plasma Emission Characteristics from a High Current Hollow Cathode in an Ion Thruster Discharge Chamber

    NASA Technical Reports Server (NTRS)

    Foster, John E.; Patterson, Michael J.

    2002-01-01

    The presence of energetic ions produced by a hollow cathodes operating at high emission currents (greater than 5A) has been documented in the literature. In order to further elucidate these findings, an investigation of a high current cathode operating in an ion thruster discharge chamber has been undertaken. Using Langmuir probes, a low energy charged particle analyzer and emission spectroscopy, the behavior of the near-cathode plasma and the emitted ion energy distribution was characterized. The presence of energetic ions was confirmed. It was observed that these ions had energies in excess of the discharge voltage and thus cannot be simply explained by ions falling out of plasma through a potential difference of this order. Additionally, evidence provided by Langmuir probes suggests the existence of a double layer essentially separating the hollow cathode plasma column from the main discharge. The radial potential difference associated with this double layer was measured to be of order the ionization potential.

  1. TH-C-19A-08: PDD Discrepancies at Opposite Biases From Very Small Volume Ion Chambers When Using Water Scanners

    SciTech Connect

    Sarkar, V; Zhao, H; Rassiah-Szegedi, P; Huang, Y; Szegedi, M; Huang, L; Salter, B; Wang, B; James, J; McCullough, K; Lynch, B

    2014-06-15

    Purpose: As more so-called micro ion chambers become commercially available, medical physicists may be inclined to use them during the linear accelerator commissioning process, in an attempt to better characterize the beam in steep dose gradient areas. The purpose of this work is to inform the medical physics community of a non-trivial, anomalous behavior observed when very small chambers are used in certain beam scanning configurations. Methods: A total of six ion chambers (0.007cc to 0.6cc) were used to scan PDDs from a 10×10cm2 field at both +300V and −300V biases. PDDs were scanned using three different water tank scanning systems to determine whether different scanners exhibit the same abnormality. Finally, PDDs were sampled using an external electrometer to bypass the internal electrometer of the scanner to determine the potential contributions of the scanner electronics to the abnormality observed. Results: We observed a reproducible, significant difference (over-response with depth) in PDDs acquired when using very small ion chambers with certain bias and watertank combinations, on the order of 3–5% at a depth of 25 cm in water. This difference was not observed when the PDDs were sampled using the ion chambers in conjunction with an external electrometer. This suggests a contribution of interference produced by the controller box and scanning system, which becomes significant for the very small signals collected by very small ion chambers, especially at depth, as the signal level is reduced even further. Conclusion: Based on the results observed here, if currently available very small ion chambers are used with specific bias and scanning water-tank combinations, erroneous PDD data may be collected. If this data is used as input to the Treatment Planning System, systematic errors on the order of 3%–5% may be introduced into the treatment planning process.

  2. Computational Study of Primary Electrons in the Cusp Region of an Ion Engine's Discharge Chamber

    NASA Technical Reports Server (NTRS)

    Stueber, Thomas J. (Technical Monitor); Deshpande, Shirin S.; Mahalingam, Sudhakar; Menart, James A.

    2004-01-01

    In this work a computer code called PRIMA is used to study the motion of primary electrons in the magnetic cusp region of the discharge chamber of an ion engine. Even though the amount of wall area covered by the cusps is very small, the cusp regions are important because prior computational analyses have indicated that most primary electrons leave the discharge chamber through the cusps. The analysis presented here focuses on the cusp region only. The affects of the shape and size of the cusp region on primary electron travel are studied as well as the angle and location at which the electron enters the cusp region. These affects are quantified using the confinement length and the number density distributions of the primary electrons. In addition to these results comparisons of the results from PRIMA are made to experimental results for a cylindrical discharge chamber with two magnetic rings. These comparisons indicate the validity of the computer code called PRIMA.

  3. Characterization and use of a 2D-array of ion chambers for brachytherapy dosimetric quality assurance

    SciTech Connect

    Yewondwossen, Mammo

    2012-10-01

    The two-dimensional (2D) ionization chamber array MatriXX Evolution is one of the 2D ionization chamber arrays developed by IBA Dosimetry (IBA Dosimetry, Germany) for megavoltage real-time absolute 2D dosimetry and verification of intensity-modulated radiation therapy (IMRT). The purpose of this study was to (1) evaluate the performance of ion chamber array for submegavoltage range brachytherapy beam dose verification and quality assurance (QA) and (2) use the end-to-end dosimetric evaluation that mimics a patient treatment procedure and confirm the primary source strength calibration agrees in both the treatment planning system (TPS) and treatment delivery console computers. The dose linearity and energy dependence of the 2D ion chamber array was studied using kilovoltage X-ray beams (100, 180 and 300 kVp). The detector calibration factor was determined using 300 kVp X-ray beams so that we can use the same calibration factor for dosimetric verification of high-dose-rate (HDR) brachytherapy. The phantom used for this measurement consists of multiple catheters, the IBA MatriXX detector, and water-equivalent slab of RW3 to provide full scattering conditions. The treatment planning system (TPS) (Oncentra brachy version 3.3, Nucletron BV, Veenendaal, the Netherlands) dose distribution was calculated on the computed tomography (CT) scan of this phantom. The measured and TPS calculated distributions were compared in IBA Dosimetry OmniPro-I'mRT software. The quality of agreement was quantified by the gamma ({gamma}) index (with 3% delta dose and distance criterion of 2 mm) for 9 sets of plans. Using a dedicated phantom capable of receiving 5 brachytherapy intralumenal catheters a QA procedure was developed for end-to-end dosimetric evaluation for routine QA checks. The 2D ion chamber array dose dependence was found to be linear for 100-300 kVp and the detector response (k{sub user}) showed strong energy dependence for 100-300 kVp energy range. For the Ir-192 brachytherapy

  4. Response to NAS Request for Information on Chamber Repetition Rate

    SciTech Connect

    Meier, Wayne R.

    2011-08-19

    This purpose of this report is to “Provide further information on the issues of repetition rates and chamber clearing issues for dry wall and liquid wall chamber concepts for IFE; namely what are the issues, possible solutions and needed R&D?”

  5. Methods and apparatus for cleaning objects in a chamber of an optical instrument by generating reactive ions using photon radiation

    DOEpatents

    Klebanoff, Leonard E.; Delgado, Gildardo R.; Hollenshead, Jeromy T.; Umstadter, Karl R.; Starodub, Elena; Zhuang, Guorong V.

    2015-10-13

    An optical instrument, including a chamber, an object exposed to an interior of the chamber, a source of low-pressure gas, the gas comprising at least one of low-pressure molecular hydrogen gas, low-pressure molecular oxygen and a low-pressure noble gas, the source of low pressure gas being fluidly coupled to the chamber, a low voltage source electrically coupled between the object and a remaining portion of the instrument that is exposed to the interior of the chamber so as to maintain the object at a low voltage relative to the remaining portion, and an EUV/VUV light source adapted to direct EUV/VUV light through the low pressure gas in the chamber onto the object. In such a system, when the EUV/VUV light source is activated ions of the low-pressure gas are formed and directed to the object. The ions may be ions of Hydrogen, Oxygen or a noble gas.

  6. Monte Carlo calculations for reference dosimetry of electron beams with the PTW Roos and NE2571 ion chambers

    SciTech Connect

    Muir, B. R. Rogers, D. W. O.

    2013-12-15

    Purpose: To investigate recommendations for reference dosimetry of electron beams and gradient effects for the NE2571 chamber and to provide beam quality conversion factors using Monte Carlo simulations of the PTW Roos and NE2571 ion chambers. Methods: The EGSnrc code system is used to calculate the absorbed dose-to-water and the dose to the gas in fully modeled ion chambers as a function of depth in water. Electron beams are modeled using realistic accelerator simulations as well as beams modeled as collimated point sources from realistic electron beam spectra or monoenergetic electrons. Beam quality conversion factors are calculated with ratios of the doses to water and to the air in the ion chamber in electron beams and a cobalt-60 reference field. The overall ion chamber correction factor is studied using calculations of water-to-air stopping power ratios. Results: The use of an effective point of measurement shift of 1.55 mm from the front face of the PTW Roos chamber, which places the point of measurement inside the chamber cavity, minimizes the difference betweenR{sub 50}, the beam quality specifier, calculated from chamber simulations compared to that obtained using depth-dose calculations in water. A similar shift minimizes the variation of the overall ion chamber correction factor with depth to the practical range and reduces the root-mean-square deviation of a fit to calculated beam quality conversion factors at the reference depth as a function of R{sub 50}. Similarly, an upstream shift of 0.34 r{sub cav} allows a more accurate determination of R{sub 50} from NE2571 chamber calculations and reduces the variation of the overall ion chamber correction factor with depth. The determination of the gradient correction using a shift of 0.22 r{sub cav} optimizes the root-mean-square deviation of a fit to calculated beam quality conversion factors if all beams investigated are considered. However, if only clinical beams are considered, a good fit to results for

  7. Heavy-ion inertial fusion: influence of target gain on accelerator parameters for vacuum-propagation regimes in reaction chambers

    SciTech Connect

    Mark, J.W.K.; Bangerter, R.O.; Barletta, W.A.; Fawley, W.M.; Judd, D.L.

    1982-03-04

    Target physics imposes requirements on the design of inertial fusion drivers. The influence of beam propagation in near vacuum fusion reaction chambers is evaluated for the relation between target gain and the phase-space requirements of heavy-ion accelerators. Initial results suggest that neutralization of the ion beam has a much greater positive effect than the deleterious one of beam stripping provided that the fusion chamber pressure is < 10/sup -3/ torr (of Li vapor or equivalent).

  8. Solutions for discharge chamber sputtering and anode deposit spalling in small mercury ion thrusters

    NASA Technical Reports Server (NTRS)

    Power, J. L.; Hiznay, D. J.

    1975-01-01

    Proposed solutions to the problems of sputter erosion and sputtered material spalling in the discharge chamber of small mercury ion thrusters are presented. The accelerated life test evaluated three such proposed solutions: (1) the use of tantalum as a single low sputter yield material for the exposed surfaces of the discharge chamber components subject to sputtering, (2) the use of a severely roughened anode surface to improve the adhesion of the sputter-deposited coating, and (3) the use of a wire cloth anode surface in order to limit the size of any coating flakes which might spall from it. Because of the promising results obtained in the accelerated life test with anode surfaces roughened by grit-blasting, experiments were carried out to optimize the grit-blasting procedure. The experimental results and an optimal grit-blasting procedure are presented.

  9. Sputtering phenomena of discharge chamber components in a 30-cm diameter Hg ion thruster

    NASA Technical Reports Server (NTRS)

    Mantenieks, M. A.; Rawlin, V. K.

    1976-01-01

    Sputtering and deposition rates were measured for discharge chamber components of a 30-cm diameter mercury ion thruster. It was found that sputtering rates of the screen grid and cathode baffle were strongly affected by geometry of the baffle holder. Sputtering rates of the baffle and screen grid were reduced to 80 and 125 A/hr, respectively, by combination of appropriate geometry and materials selections. Sputtering rates such as these are commensurate with thruster lifetimes of 15,000 hours or more. A semiempirical sputtering model showed good agreement with the measured values.

  10. An exposure chamber for studies on human perception of DC electric fields and ions

    SciTech Connect

    Nguyen, D.H.; Maruvada, P.S. )

    1994-10-01

    Direct current (DC) transmission lines are often used, for technical and economic reasons, as interconnections in modern high voltage power systems, which are essentially of the alternating current (AC) type. Significant differences exist, however, between the field effects produced in the vicinity of AC and DC transmission lines. DC electric fields induce charges, on the surface of a conducting body such as a human being and may therefore be ''perceived'' by humans due to hair stimulation and other sensations experienced by the skin. A human being exposed to the ionized field of a DC transmission line experiences not only surface charges but also the conducted ion currents. A systematic laboratory study has been undertaken by Hydro Quebec to investigate human perception, using well established psycho physical techniques, of DC electric fields and ions. The design, construction and operation of an exposure chamber for this purpose, in the high voltage laboratory of IREQ, are described in this paper.

  11. Two-chamber configuration of Bio-Nano electron cyclotron resonance ion source for fullerene modification

    SciTech Connect

    Uchida, T.; Rácz, R.; Biri, S.; Kato, Y.; Yoshida, Y.

    2016-02-15

    We report on the modification of fullerenes with iron and chlorine using two individually controllable plasmas in the Bio-Nano electron cyclotron resonance ion source (ECRIS). One of the plasmas is composed of fullerene and the other one is composed of iron and chlorine. The online ion beam analysis allows one to investigate the rate of the vapor-phase collisional modification process in the ECRIS, while the offline analyses (e.g., liquid chromatography-mass spectrometry) of the materials deposited on the plasma chamber can give information on the surface-type process. Both analytical methods show the presence of modified fullerenes such as fullerene-chlorine, fullerene-iron, and fullerene-chlorine-iron.

  12. Two-chamber configuration of Bio-Nano electron cyclotron resonance ion source for fullerene modification

    NASA Astrophysics Data System (ADS)

    Uchida, T.; Rácz, R.; Muramatsu, M.; Kato, Y.; Kitagawa, A.; Biri, S.; Yoshida, Y.

    2016-02-01

    We report on the modification of fullerenes with iron and chlorine using two individually controllable plasmas in the Bio-Nano electron cyclotron resonance ion source (ECRIS). One of the plasmas is composed of fullerene and the other one is composed of iron and chlorine. The online ion beam analysis allows one to investigate the rate of the vapor-phase collisional modification process in the ECRIS, while the offline analyses (e.g., liquid chromatography-mass spectrometry) of the materials deposited on the plasma chamber can give information on the surface-type process. Both analytical methods show the presence of modified fullerenes such as fullerene-chlorine, fullerene-iron, and fullerene-chlorine-iron.

  13. Two-chamber configuration of Bio-Nano electron cyclotron resonance ion source for fullerene modification.

    PubMed

    Uchida, T; Rácz, R; Muramatsu, M; Kato, Y; Kitagawa, A; Biri, S; Yoshida, Y

    2016-02-01

    We report on the modification of fullerenes with iron and chlorine using two individually controllable plasmas in the Bio-Nano electron cyclotron resonance ion source (ECRIS). One of the plasmas is composed of fullerene and the other one is composed of iron and chlorine. The online ion beam analysis allows one to investigate the rate of the vapor-phase collisional modification process in the ECRIS, while the offline analyses (e.g., liquid chromatography-mass spectrometry) of the materials deposited on the plasma chamber can give information on the surface-type process. Both analytical methods show the presence of modified fullerenes such as fullerene-chlorine, fullerene-iron, and fullerene-chlorine-iron.

  14. Characterization of Si distribution at the tungsten/titanium nitride interface using secondary ion mass spectrometry — an investigation of the dynamic response of a chemical vapor deposition chamber

    NASA Astrophysics Data System (ADS)

    Jones, Clive M.; Zhao, Jin; Yuan, Ting

    2000-09-01

    Secondary ion mass spectrometry (SIMS) was successfully used as an analytical method to characterize chemical vapor deposited (CVD) tungsten (W) processes. Blanket CVD tungsten film on titanium nitride (TiN) barrier layers generally begins with the deposition of a tungsten nucleation layer by silane (SiH 4) reduction of tungsten hexafluoride (WF 6), followed by hydrogen (H 2) reduction of WF 6 alone to form the bulk tungsten layer. In the present work, the tungsten nucleation layer was formed by simultaneous SiH 4 and H 2 reduction of WF 6. A two-step SiH 4 gas flow scheme was used to determine the effects of magnitude and duration of SiH 4 flow on the Si concentration at the W/TiN interface. SIMS was used to characterize the Si distribution at the CVD W/TiN interface. SIMS depth profiles indicate, with a constant SiH 4 flow time of 3 s, the Si concentration at W/TiN interface does not vary significantly with the increase of SiH 4 flow from 20 to 30 sccm. However, it increases dramatically with the increase of SiH 4 flow from 30 to 48 sccm. With a constant SiH 4 flow of 40 sccm, the Si concentration at the W/TiN interface increases linearly with the increase of the SiH 4 flow time. These results amply demonstrate that SIMS analysis can be used to evaluate the deposition process so as to meet the fill and barrier protection requirements for narrow trench or small via.

  15. Dosimetric verification of gated delivery of electron beams using a 2D ion chamber array.

    PubMed

    Yoganathan, S A; Das, K J Maria; Raj, D Gowtham; Kumar, Shaleen

    2015-01-01

    The purpose of this study was to compare the dosimetric characteristics; such as beam output, symmetry and flatness between gated and non-gated electron beams. Dosimetric verification of gated delivery was carried for all electron beams available on Varian CL 2100CD medical linear accelerator. Measurements were conducted for three dose rates (100 MU/min, 300 MU/min and 600 MU/min) and two respiratory motions (breathing period of 4s and 8s). Real-time position management (RPM) system was used for the gated deliveries. Flatness and symmetry values were measured using Imatrixx 2D ion chamber array device and the beam output was measured using plane parallel ion chamber. These detector systems were placed over QUASAR motion platform which was programmed to simulate the respiratory motion of target. The dosimetric characteristics of gated deliveries were compared with non-gated deliveries. The flatness and symmetry of all the evaluated electron energies did not differ by more than 0.7 % with respect to corresponding non-gated deliveries. The beam output variation of gated electron beam was less than 0.6 % for all electron energies except for 16 MeV (1.4 %). Based on the results of this study, it can be concluded that Varian CL2100 CD is well suitable for gated delivery of non-dynamic electron beams.

  16. Electret ion chamber radon monitors measure dissolved 222Rn in water.

    PubMed

    Kotrappa, P; Jester, W A

    1993-04-01

    This paper describes a simple and relatively inexpensive method of determining the concentration of dissolved 222Rn in water. The method involves a recently developed electret-passive environmental radon monitor, which uses an electret ion chamber. The procedure consists of sealing a known volume of a carefully collected water sample with one of these monitors in an exposure container and determining the average equilibrium 222Rn gas concentration in the air phase during the exposure time period. This average concentration can then be used to calculate the 222Rn concentration in the original water sample. Identical samples were analyzed both by this new method and by a standard liquid scintillation method, and the results were compared over a wide range of 222Rn concentrations. There was good agreement except that the electret ion chamber method gave results that were consistently lower by about 15%. This bias in the results was attributed to both 222Rn losses during sample handling and possibly to some errors in the assumptions made in the theoretical model. A correction factor is recommended to bring the results of this technique into agreement with the standard method. The procedures are simple and economical and can be easily employed by many primary 222Rn-measuring laboratories currently using these monitors for measuring indoor 222Rn.

  17. Ion response in a weakly ionized plasma with ion flow

    SciTech Connect

    Kompaneets, Roman; Tyshetskiy, Yuriy O.; Vladimirov, Sergey V.

    2013-04-15

    We study the ion response to an initial perturbation in a weakly ionized plasma with ion flow driven by a dc electric field. The analysis is made by extending the classical Landau work [J. Phys. (USSR) 10, 25 (1946)] to the ion kinetic equation including ion-neutral collisions and a dc electric field. We show, in particular, that the complex frequencies of ion waves can be directly found from a known expression for the ion susceptibility [A. V. Ivlev et al., Phys. Rev. E 71, 016405 (2005); V. A. Schweigert, Phys. Rep. 27, 997 (2001)]; this is not obvious from its original derivation, because it only aims to describe the ion response for real frequencies.

  18. Simulation of ion chamber signals in the n+3 He -> p + t experiment

    NASA Astrophysics Data System (ADS)

    Coppola, Christopher; n3He Collaboration

    2017-01-01

    The parity violating proton directional asymmetry from the capture of polarized neutrons on 3He was measured with a pulsed neutron beam at the Spallation Neutron Source at Oak Ridge National Laboratory. The target is an ion chamber with 3He at 0.476 atmosphere. Signal wires in the chamber have different sensitivities to the physics asymmetry, depdendent on their location and the configuration of the experiment. These geometry factors must be determined by simulation. In addition, simulation estimates the statistical precision of the experiment, optimizes configuration variables, and assists with systematic analysis. To achieve the most accurate simulation of the detector signals, a custom simulation was written in C++ using weighted variables and taking advantage of parallel execution. The phsyics inputs to the simulation came from measurements of the neutron phase space, ENDF cross sections, and PSTAR ionization data. A cell model was applied to combine this physics to produce an accurate simulation of the experimental data. This simulation can be used to calculate accurate and tunable geometry factors, and to produce desired quanities for use in optimization and analysis.

  19. Performance of single chamber biocatalyzed electrolysis with different types of ion exchange membranes.

    PubMed

    Rozendal, René A; Hamelers, Hubertus V M; Molenkamp, Redmar J; Buisman, Cees J N

    2007-05-01

    In this paper hydrogen production through biocatalyzed electrolysis was studied for the first time in a single chamber configuration. Single chamber biocatalyzed electrolysis was tested in two configurations: (i) with a cation exchange membrane (CEM) and (ii) with an anion exchange membrane (AEM). Both configurations performed comparably and produced over 0.3 m3 H2/m3 reactor liquid volume/day at 1.0 V applied voltage (overall hydrogen efficiencies around 23%). Analysis of the water that permeated through the membrane revealed that a large part of potential losses in the system were associated with a pH gradient across the membrane (CEM DeltapH=6.4; AEM DeltapH=4.4). These pH gradient associated potential losses were lower in the AEM configuration (CEM 0.38 V; AEM 0.26 V) as a result of its alternative ion transport properties. This benefit of the AEM, however, was counteracted by the higher cathode overpotentials occurring in the AEM configuration (CEM 0.12 V at 2.39 A/m2; AEM 0.27 V at 2.15 A/m2) as a result of a less effective electroless plating method for the AEM membrane electrode assembly (MEA).

  20. Phantom dosimetric study of nondivergent aluminum tissue compensator using ion chamber, TLD, and gafchromic film.

    PubMed

    Kinhikar, Rajesh A; Tambe, Chandrashekhar M; Upreti, Ritu R; Patkar, Sachin; Patil, Kalpana; Deshpande, Deepak D

    2008-01-01

    Anatomic contour irregularity and tissue inhomogeneity in head-and-neck radiotherapy can lead to significant dose inhomogeneity due to the presence of hot and cold spots across the treatment volumes. Missing tissue compensators (TCs) can overcome this dose inhomogeneity. The current study examines the capacity of 2-dimensional (2D) custom aluminum TCs fabricated at our hospital to improve the dose homogeneity across the treatment volume. The dosimetry of the 2D custom TCs was carried out in a specially designed head-and-neck phantom for anterior-posterior (AP) and posterior-anterior (PA) fields with an ion chamber, thermoluminscence dosimeters (TLDs), and film. The results were compared for compensated and uncompensated plans generated from the Eclipse treatment planning system. On average, open-field plans contained peak doses of 117%, optimally wedged-plans contained peak doses of 113%, and custom-compensated plans contained peak doses of 105%. The dose variation between prescribed and measured dose at midplane of the phantom was observed as high as 17%, which was reduced to 3.2% for the customized TC during ionometric measurements. It was further confirmed with TLDs, in a sagittal plane, that the high-dose region of 13.3% was reduced to 2.3%. The measurements carried out with the ion chamber, TLDs, and film were found in good agreement with each other and with Eclipse. Thus, a custom-made 2D TC is capable of reducing hot spots to improve overall dose homogeneity across the treatment volume.

  1. SU-E-T-562: Scanned Percent Depth Dose Curve Discrepancy for Photon Beams with Physical Wedge in Place (Varian IX) Using Different Sensitive Volume Ion Chambers

    SciTech Connect

    Zhao, H; Sarkar, V; Rassiah-Szegedi, P; Huang, Y; Szegedi, M; Huang, L; Salter, B

    2014-06-01

    Purpose: To investigate and report the discrepancy of scanned percent depth dose (PDD) for photon beams with physical wedge in place when using ion chambers with different sensitive volumes. Methods/Materials: PDD curves of open fields and physical wedged fields (15, 30, 45, and 60 degree wedge) were scanned for photon beams (6MV and 10MV, Varian iX) with field size of 5x5 and 10x10 cm using three common scanning chambers with different sensitive volumes - PTW30013 (0.6cm3), PTW23323 (0.1cm3) and Exradin A16 (0.007cm3). The scanning system software used was OmniPro version 6.2, and the scanning water tank was the Scanditronix Wellhoffer RFA 300.The PDD curves from the three chambers were compared. Results: Scanned PDD curves of the same energy beams for open fields were almost identical between three chambers, but the wedged fields showed non-trivial differences. The largest differences were observed between chamber PTW30013 and Exradin A16. The differences increased as physical wedge angle increased. The differences also increased with depth, and were more pronounced for 6MV beam. Similar patterns were shown for both 5x5 and 10x10 cm field sizes. For open fields, all PDD values agreed with each other within 1% at 10cm depth and within 1.62% at 20 cm depth. For wedged fields, the difference of PDD values between PTW30013 and A16 reached 4.09% at 10cm depth, and 5.97% at 20 cm depth for 6MV with 60 degree physical wedge. Conclusion: We observed a significant difference in scanned PDD curves of photon beams with physical wedge in place obtained when using different sensitive volume ion chambers. The PDD curves scanned with the smallest sensitive volume ion chamber showed significant difference from larger chamber results, beyond 10cm depth. We believe this to be caused by varying response to beam hardening by the wedges.

  2. Transplantation immunology of the anterior chamber of the eye. II. Immune response to allogeneic cells.

    PubMed

    Kaplan, H J; Streilein, J W; Stevens, T R

    1975-09-01

    The mechanism by which the anterior chamber of the eye extends immunologic privilege to allogeneic donor tissues has been studied in inbred rats. Inoculation of allogeneic lymphoid cells into the anterior chamber demonstrated that although the site lacks a lymphatic drainage, the afferent limb of the immunologic reflex arc is intact because the recipient can recognize and mount a specific immune response. In addition, host immunity was able to express itself within the anterior chamber when induced systemically, indicating that the efferent limb of the reflex arc is also intact. Therefore, it is suggested that the unique immunologic features of the anterior chamber may result from the obligate intravenous presentation of graft antigen to the host's systemic immunologic apparatus, a route that prejudices the host's response in the direction of tolerance and/or enhancement rather than cell-mediated, tissue destructive immunity.

  3. Influence of pressurized anode chamber on ion transports and power generation of UF membrane microbial fuel cells (UF-MFCs)

    NASA Astrophysics Data System (ADS)

    Kim, Kyoung-Yeol; Chae, Kyu-Jung; Yang, Euntae; Lee, Mi-Young; Kim, In S.

    2015-04-01

    Ultrafiltration membrane integrated microbial fuel cell (UF-MFC) has developed to produce high-quality effluents by integrating the membrane filtration process into the MFC system. During UF-MFC operation, however, unexpected power reductions were observed under different pressures that were applied in the anode chamber (22.0% and 25.5% at 0.7 bar and 2.1 bar, respectively). It was hypothesized that those of power reductions might occur due to the limitation of ion transport across the UF membrane- which could be caused by the pressurized anode chamber to filter the anode solution through the UF membrane. A test with a NaCl concentrated cathode solution showed few dissolved ions being transported from the cathode to anode chamber while the pressure was being applied in the anode chamber. This result clearly indicates that the limitation of ion transport from the cathode to the pressurized anode chamber is a significant factor affecting the power density of UF-MFCs, even more so than water permeation through the UF membrane.

  4. Heavy ion beam propagation through a gas-filled chamber for inertial confinement fusion

    SciTech Connect

    Barboza, Nigel Oswald

    1996-10-01

    The work presented here evaluates the dynamics of a beam of heavy ions propagating through a chamber filled with gas. The motivation for this research stems from the possibility of using heavy ion beams as a driver in inertial confinement fusion reactors for the purpose of generating electricity. Such a study is important in determining the constraints on the beam which limit its focus to the small radius necessary for the ignition of thermonuclear microexplosions which are the source of fusion energy. Nuclear fusion is the process of combining light nuclei to form heavier ones. One possible fusion reaction combines two isotopes of hydrogen, deuterium and tritium, to form an alpha particle and a neutron, with an accompanying release of ~17.6 MeV of energy. Generating electricity from fusion requires that we create such reactions in an efficient and controlled fashion, and harness the resulting energy. In the inertial confinement fusion (ICF) approach to energy production, a small spherical target, a few millimeters in radius, of deuterium and tritium fuel is compressed so that the density and temperature of the fuel are high enough, ~200 g/cm3 and ~20 keV, that a substantial number of fusion reactions occur; the pellet microexplosion typically releases ~350 MJ of energy in optimized power plant scenarios.

  5. Integration of a broad beam ion source with a high-temperature x-ray diffraction vacuum chamber

    SciTech Connect

    Manova, D.; Bergmann, A.; Maendl, S.; Neumann, H.; Rauschenbach, B.

    2012-11-15

    Here, the integration of a low energy, linearly variable ion beam current density, mechanically in situ adjustable broad beam ion source with a high-temperature x-ray diffraction (XRD) vacuum chamber is reported. This allows in situ XRD investigation of phase formation and evolution processes induced by low energy ion implantation. Special care has been taken to an independent adjustment of the ion beam for geometrical directing towards the substrate, a 15 mm small ion source exit aperture to avoid a secondary sputter process of the chamber walls, linearly variable ion current density by using a pulse length modulation (PLM) for the accelerating voltages without changing the ion beam density profile, nearly homogeneous ion beam distribution over the x-ray footprint, together with easily replaceable Kapton{sup Registered-Sign} windows for x-rays entry and exit. By combining a position sensitive x-ray detector with this PLM-modulated ion beam, a fast and efficient time resolved investigation of low energy implantation processes is obtained in a compact experimental setup.

  6. Integration of a broad beam ion source with a high-temperature x-ray diffraction vacuum chamber

    NASA Astrophysics Data System (ADS)

    Manova, D.; Bergmann, A.; Mändl, S.; Neumann, H.; Rauschenbach, B.

    2012-11-01

    Here, the integration of a low energy, linearly variable ion beam current density, mechanically in situ adjustable broad beam ion source with a high-temperature x-ray diffraction (XRD) vacuum chamber is reported. This allows in situ XRD investigation of phase formation and evolution processes induced by low energy ion implantation. Special care has been taken to an independent adjustment of the ion beam for geometrical directing towards the substrate, a 15 mm small ion source exit aperture to avoid a secondary sputter process of the chamber walls, linearly variable ion current density by using a pulse length modulation (PLM) for the accelerating voltages without changing the ion beam density profile, nearly homogeneous ion beam distribution over the x-ray footprint, together with easily replaceable Kapton® windows for x-rays entry and exit. By combining a position sensitive x-ray detector with this PLM-modulated ion beam, a fast and efficient time resolved investigation of low energy implantation processes is obtained in a compact experimental setup.

  7. Integration of a broad beam ion source with a high-temperature x-ray diffraction vacuum chamber.

    PubMed

    Manova, D; Bergmann, A; Mändl, S; Neumann, H; Rauschenbach, B

    2012-11-01

    Here, the integration of a low energy, linearly variable ion beam current density, mechanically in situ adjustable broad beam ion source with a high-temperature x-ray diffraction (XRD) vacuum chamber is reported. This allows in situ XRD investigation of phase formation and evolution processes induced by low energy ion implantation. Special care has been taken to an independent adjustment of the ion beam for geometrical directing towards the substrate, a 15 mm small ion source exit aperture to avoid a secondary sputter process of the chamber walls, linearly variable ion current density by using a pulse length modulation (PLM) for the accelerating voltages without changing the ion beam density profile, nearly homogeneous ion beam distribution over the x-ray footprint, together with easily replaceable Kapton(®) windows for x-rays entry and exit. By combining a position sensitive x-ray detector with this PLM-modulated ion beam, a fast and efficient time resolved investigation of low energy implantation processes is obtained in a compact experimental setup.

  8. Construction of a scattering chamber for ion-beam analysis of environmental materials in undergraduate physics research

    SciTech Connect

    LaBrake, Scott M.; Vineyard, Michael F.; Turley, Colin F.; Moore, Robert D.; Johnson, Christopher

    2013-04-19

    We have developed a new scattering chamber for ion-beam analysis of environmental materials with the 1.1-MV Pelletron accelerator at the Union College Ion-Beam Analysis Laboratory. The chamber was constructed from a ten-inch, Conflat, multi-port cross and includes a three-axis target manipulator and target ladder assembly, an eight-inch turbo pump, an Amptek X-ray detector, and multiple charged particle detectors. Recent projects performed by our undergraduate research team include proton induced X-ray emission (PIXE) and Rutherford backscattering (RBS) analyses of atmospheric aerosols collected with a nine-stage cascade impactor in Upstate New York. We will describe the construction of the chamber and discuss the results of some commissioning experiments.

  9. Filifactor alocis Infection and Inflammatory Responses in the Mouse Subcutaneous Chamber Model

    PubMed Central

    Wang, Qian; Jotwani, Ravi; Le, Junyi; Krauss, Jennifer L.; Potempa, Jan; Coventry, Susan C.

    2014-01-01

    Recent microbiome studies have implicated a role for Filifactor alocis in periodontal disease. In this study, we investigated the colonization and survival properties of F. alocis in a mouse subcutaneous chamber model of infection and characterized host innate immune responses. An infection of 109 F. alocis successfully colonized all chambers; however, the infection was cleared after 72 h. F. alocis elicited a local inflammatory response with neutrophils recruited into the chambers at 2 h postinfection along with an increase in levels of the proinflammatory cytokines interleukin 1β (IL-1β), IL-6, and tumor necrosis factor (TNF). F. alocis also induced apoptosis in chamber epithelial cells and neutrophils. Consistent with resolution of infection, neutrophil numbers and cytokine levels returned to baseline by 72 h. Fluorescent in situ hybridization (FISH) and quantitative PCR demonstrated that F. alocis exited the chambers and spread to the spleen, liver, lung, and kidney. Massive neutrophil infiltration was observed in the spleen and lungs, and the recruited neutrophils were in close proximity to the infecting bacteria. Significant epithelial injury was observed in the kidneys. Infection of all tissues was resolved after 7 days. This first in vivo study of the pathogenicity of F. alocis shows that in the chamber model the organism can establish a proinflammatory, proapoptotic local infection which is rapidly resolved by the host concordant with neutrophil influx. Moreover, F. alocis can spread to, and transiently infect, remote tissues where neutrophils can also be recruited. PMID:24379289

  10. Early and Late Responses to Ion Irradiation

    NASA Astrophysics Data System (ADS)

    Schulte, Reinhard; Ling, Ted

    Early and late responses to ion beam therapy (IBT) are the result of complex interactions between host, dose volume, and radiobiological factors. Our understanding of these early and late tissue responses has improved greatly with the accumulation of laboratory and clinical experience with proton and heavy ion irradiation. With photon therapy becoming increasingly conformal, many concepts developed for 3D conformal radiotherapy and intensity modulated radiation therapy with photons are also applicable to IBT. This chapter reviews basic concepts and experimental data of early and late tissue responses to protons and ions.

  11. Development of a Novel Contamination Resistant Ion Chamber for Process Tritium Measurement and Use in the JET First Trace Tritium Experiment

    SciTech Connect

    Worth, L.B.C.; Pearce, R.J.H.; Bruce, J.; Banks, J.; Scales, S.

    2005-07-15

    The accuracy of process measurements of tritium with conventional ion chambers is often affected by surface tritium contamination. The measurement of tritium in the exhaust of the JET torus is particularly difficult due to surface contamination with highly tritiated hydrocarbons. JET's first unsuccessful attempt to overcome the contamination problem was to use an ion chamber, with a heating element as the chamber wall so that it could be periodically decontaminated by baking. The newly developed ion chamber works on the principle of minimising the surface area within the boundary of the anode and cathode.This paper details the design of the ion chamber, which utilises a grid of 50-micron tungsten wire to define the ion chamber wall and the collector electrode. The effective surface area which, by contamination, is able to effect the measurement of tritium within the process gas has been reduced by a factor of {approx}200 over a conventional ion chamber. It is concluded that the new process ion chamber enables sensitive accurate tritium measurements free from contamination issues. It will be a powerful new tool for future tritium experiments both to improve tritium tracking and to help in the understanding of tritium retention issues.

  12. Experimental validation of a versatile system of CT dosimetry using a conventional ion chamber: Beyond CTDI{sub 100}

    SciTech Connect

    Dixon, Robert L.; Ballard, Adam C.

    2007-08-15

    This article is an experimental demonstration and authentication of a new method of computed tomography dosimetry [R. L. Dixon, Med. Phys. 30, 1272-1280 (2003)], which utilizes a short, conventional ion chamber rather than a pencil chamber, and which is more versatile than the latter. The value of CTDI{sub 100} correctly predicts the accumulated dose only for a total scan length L equal to 100 mm and underestimates the limiting equilibrium dose approached for longer, clinically relevant body scan lengths [R. L. Dixon, Med. Phys. 30, 1272-1280 (2003); K. D. Nakonechny, B. G. Fallone, and S. Rathee, Med. Phys. 32, 98-109 (2005); S. Mori, M. Endo, K. Nishizawa, T. Tsunoo, T. Aoyama, H. Fujiwara, and K. Murase, Med. Phys. 32, 1061-1069 (2005); R. L. Dixon, M. T. Munley, and E. Bayram, Med. Phys. 32, 3712-3728 (2005); R. L. Dixon, Med. Phys. 33, 3973-3976 (2006)]. Dixon [Med. Phys. 30, 1272-1280 (2003)] originally proposed an alternative using a short ion chamber and a helical scan acquisition to collect the same integral for any scan length L (and not limited 100 mm). The primary purpose of this work is to demonstrate experimentally the implementation, robustness, and versatility of this small ion chamber method in measuring the accumulated dose in the body phantom for any desired scan length L (up to the available phantom length) including the limiting equilibrium dose (symbolically CTDI{sub {infinity}}), and validation of the method against the pencil chamber methodology. Additionally, a simple and robust method for independently verifying the active length of a pencil chamber is described. The results of measurements made in a 400 mm long, 32 cm diameter polymethylmethacrylate body phantom using a small Farmer-type ion chamber and two pencil chambers of lengths l=100 and 150 mm confirm that the two methodologies provide the same dose values at the corresponding scan lengths L=l. The measured equilibrium doses obtained for GE MDCT scanners at 120 kVp are CTDI

  13. On-line quality assurance of rotational radiotherapy treatment delivery by means of a 2D ion chamber array and the Octavius phantom

    SciTech Connect

    Esch, Ann van; Clermont, Christian; Devillers, Magali; Iori, Mauro; Huyskens, Dominique P.

    2007-10-15

    For routine pretreatment verification of innovative treatment techniques such as (intensity modulated) dynamic arc therapy and helical TomoTherapy, an on-line and reliable method would be highly desirable. The present solution proposed by TomoTherapy, Inc. (Madison, WI) relies on film dosimetry in combination with up to two simultaneous ion chamber point dose measurements. A new method is proposed using a 2D ion chamber array (Seven29, PTW, Freiburg, Germany) inserted in a dedicated octagonal phantom, called Octavius. The octagonal shape allows easy positioning for measurements in multiple planes. The directional dependence of the response of the detector was primarily investigated on a dual energy (6 and 18 MV) Clinac 21EX (Varian Medical Systems, Palo Alto, CA) as no fixed angle incidences can be calculated in the Hi-Art TPS of TomoTherapy. The array was irradiated from different gantry angles and with different arc deliveries, and the dose distributions at the level of the detector were calculated with the AAA (Analytical Anisotropic Algorithm) photon dose calculation algorithm implemented in Eclipse (Varian). For validation on the 6 MV TomoTherapy unit, rotational treatments were generated, and dose distributions were calculated with the Hi-Art TPS. Multiple cylindrical ion chamber measurements were used to cross-check the dose calculation and dose delivery in Octavius in the absence of the 2D array. To compensate for the directional dependence of the 2D array, additional prototypes of Octavius were manufactured with built-in cylindrically symmetric compensation cavities. When using the Octavius phantom with a 2 cm compensation cavity, measurements with an accuracy comparable to that of single ion chambers can be achieved. The complete Octavius solution for quality assurance of rotational treatments consists of: The 2D array, two octagonal phantoms (with and without compensation layer), an insert for nine cylindrical ion chambers, and a set of inserts of

  14. Electret ion chamber-based passive radon-thoron discriminative monitors.

    PubMed

    Kotrappa, P; Steck, D

    2010-10-01

    Electret ion chambers (EICs), commercially available under brand name E-PERM(®), are widely used for measuring indoor and outdoor (222)Rn concentrations in air. These are designed to respond only to (222)Rn and not to (220)Rn by restricting diffusional entry area. Such radon EIC (R EIC) monitors are modified by increasing the entry area to allow (220)Rn, in addition to (222)Rn. Such modified units are called RT EIC. When a set of R and RT EICs are collocated, it is possible to discriminate and measure both radon and thoron concentrations, using appropriate calibration factors (CFs) and algorithms. The EICs come in different volumes, providing different sensitivities. The thoron CFs for 58-, 210- and 960-ml volume R and RT pairs are, respectively, 2.8-, 18.7- and 89-V drop per (kBq m(-3) d ), respectively. These provide much wider sensitivities and ranges compared to alpha track-based passive radon-thoron discriminative monitors.

  15. Radon exhalation rates from building materials using electret ion chamber radon monitors in accumulators.

    PubMed

    Kotrappa, Payasada; Stieff, Frederick

    2009-08-01

    An electret ion chamber (EIC) radon monitor in a sealed accumulator measures the integrated average radon concentration at the end of the accumulation duration. Theoretical equations have been derived to relate such radon concentrations (Bq m(-3) ) to the radon emanation rate (Bq d(-1)) from building materials enclosed in the accumulator. As an illustration, a 4-L sealable glass jar has been used as an accumulator to calculate the radon emanation rate from different granite samples. The radon emanation rate was converted into radon flux (Bq mm(-2) d(-1)) by dividing the emanation rate by surface area of the sample. Fluxes measured on typical, commercially available granites ranged from 20-30 Bq m(-2) d(-1). These results are similar to the results reported in the literature. The lower limit of detection for a 2-d measurement works out to be 7 Bq m(-2) d(-1). Equations derived can also be used for other sealable accumulators and other integrating detectors, such as alpha track detectors.

  16. Response of thermal ions to electromagnetic ion cyclotron waves

    NASA Technical Reports Server (NTRS)

    Anderson, B. J.; Fuselier, S. A.

    1994-01-01

    Electromagnetic ion cyclotron waves generated by 10 - 50 keV protons in the Earth's equatorial magnetosphere will interact with the ambient low-energy ions also found in this region. We examine H(+) and He(+) distribution functions from approx. equals 1 to 160 eV using the Hot Plasma Composition Experiment instrument on AMPTE/CCE to investigate the thermal ion response to the waves. A total of 48 intervals were chosen on the basis of electromagnetic ion cyclotron (EMIC) wave activity: 24 with prevalent EMIC waves and 24 with no EMIC waves observed on the orbit. There is a close correlation between EMIC waves and perpendicular heated ion distributions. For protons the perpendicular temperature increase is modest, about 5 eV, and is always observed at 90 deg pitch angles. This is consistent with a nonresonant interaction near the equator. By contrast, He(+) temperatures during EMIC wave events averaged 35 eV and sometimes exceeded 100 eV, indicating stronger interaction with the waves. Furthermore, heated He(+) ions have X-type distributions with maximum fluxes occurring at pitch angles intermediate between field-aligned and perpendicular directions. The X-type He(+) distributions are consistent with a gyroresonant interaction off the equator. The concentration of He(+) relative to H(+) is found to correlate with EMIC wave activity, but it is suggested that the preferential heating of He(+) accounts for the apparent increase in relative He(+) concentration by increasing the proportion of He(+) detected by the ion instrument.

  17. Response of thermal ions to electromagnetic ion cyclotron waves

    NASA Astrophysics Data System (ADS)

    Anderson, B. J.; Fuselier, S. A.

    1994-10-01

    Electromagnetic ion cyclotron waves generated by 10 - 50 keV protons in the Earth's equatorial magnetosphere will interact with the ambient low-energy ions also found in this region. We examine H(+) and He(+) distribution functions from approx. equals 1 to 160 eV using the Hot Plasma Composition Experiment instrument on AMPTE/CCE to investigate the thermal ion response to the waves. A total of 48 intervals were chosen on the basis of electromagnetic ion cyclotron (EMIC) wave activity: 24 with prevalent EMIC waves and 24 with no EMIC waves observed on the orbit. There is a close correlation between EMIC waves and perpendicular heated ion distributions. For protons the perpendicular temperature increase is modest, about 5 eV, and is always observed at 90 deg pitch angles. This is consistent with a nonresonant interaction near the equator. By contrast, He(+) temperatures during EMIC wave events averaged 35 eV and sometimes exceeded 100 eV, indicating stronger interaction with the waves. Furthermore, heated He(+) ions have X-type distributions with maximum fluxes occurring at pitch angles intermediate between field-aligned and perpendicular directions. The X-type He(+) distributions are consistent with a gyroresonant interaction off the equator. The concentration of He(+) relative to H(+) is found to correlate with EMIC wave activity, but it is suggested that the preferential heating of He(+) accounts for the apparent increase in relative He(+) concentration by increasing the proportion of He(+) detected by the ion instrument.

  18. Configuration of the electron transport algorithm of PENELOPE to simulate ion chambers.

    PubMed

    Sempau, J; Andreo, P

    2006-07-21

    The stability of the electron transport algorithm implemented in the Monte Carlo code PENELOPE with respect to variations of its step length is analysed in the context of the simulation of ion chambers used in photon and electron dosimetry. More precisely, the degree of violation of the Fano theorem is quantified (to the 0.1% level) as a function of the simulation parameters that determine the step size. To meet the premises of the theorem, we define an infinite graphite phantom with a cavity delimited by two parallel planes (i.e., a slab) and filled with a 'gas' that has the same composition as graphite but a mass density a thousand-fold smaller. The cavity walls and the gas have identical cross sections, including the density effect associated with inelastic collisions. Electrons with initial kinetic energies equal to 0.01, 0.1, 1, 10 or 20 MeV are generated in the wall and in the gas with a uniform intensity per unit mass. Two configurations, motivated by the design of pancake- and thimble-type chambers, are considered, namely, with the initial direction of emission perpendicular or parallel to the gas-wall interface. This version of the Fano test avoids the need of photon regeneration and the calculation of photon energy absorption coefficients, two ingredients that are common to some alternative definitions of equivalent tests. In order to reduce the number of variables in the analysis, a global new simulation parameter, called the speedup parameter (a), is introduced. It is shown that setting a = 0.2, corresponding to values of the usual PENELOPE parameters of C1 = C2 = 0.02 and values of WCC and WCR that depend on the initial and absorption energies, is appropriate for maximum tolerances of the order of 0.2% with respect to an analogue, i.e., interaction-by-interaction, simulation of the same problem. The precise values of WCC and WCR do not seem to be critical to achieve this level of accuracy. The step-size dependence of the absorbed dose is explained in

  19. Characterization of Downstream Ion Energy Distributions From a High Current Hollow Cathode in a Ring Cusp Discharge Chamber

    NASA Technical Reports Server (NTRS)

    Foster, John E.; Patterson, Michael J.

    2003-01-01

    The presence of energetic ions produced by a hollow cathodes operating at high emission currents (greater than 10 Angstroms) has been documented in the literature. As part of an ongoing effort to uncover the underlying physics of the formation of these ions, ion efflux from a high current hollow cathode operating in an ion thruster discharge chamber was investigated. Using a spherical sector electrostatic energy analyzer located downstream of the discharge cathode, the ion energy distribution over a 0 to 60 eV energy range was measured. The sensitivity of the ion energy distribution function to zenith angle was also assessed at 3 different positions: 0, 15, and 25 degrees. The measurements suggest that the majority of the ion current at the measuring point falls into the analyzer with an energy approximately equal to the discharge voltage. The ion distribution, however, was found to be quite broad. The high energy tail of the distribution function tended to grow with increasing discharge current. Sensitivity of the profiles to flow rate at fixed discharge current was also investigated. A simple model is presented that provides a potential mechanism for the production of ions with energies above the discharge voltage.

  20. The response of prototype plane-parallel ionization chambers in small megavoltage x-ray fields.

    PubMed

    McNiven, Andrea L; Mulligan, Matt; Kron, Tomas; Battista, Jerry J

    2006-11-01

    Accurate small-field dosimetry has become important with the use of multiple small fields in modern radiotherapy treatments such as IMRT and stereotactic radiosurgery. In this study, we investigate the response of a set of prototype plane-parallel ionization chambers, based upon the Exradin T11 chamber, with active volume diameters of 2, 4, 10, and 20 mm, exposed to 6 MV stereotactic radiotherapy x-ray fields. Our goal was to assess their usefulness for accurate small x-ray field dose measurements. The relative ionization response was measured in circular fields (0.5 to 4 cm diameter) as compared to a 10 x 10 cm2 reference field. A large discrepancy (approximately 40%) was found between the relative response in the smallest plane-parallel chamber and other small volume dosimeters (radiochromic film, micro-metal-oxide-semiconductor field-effect transistor and diode) used for comparison. Monte Carlo BEAMnrc simulations were used to simulate the experimental setup in order to investigate the cause of the under-response and to calculate appropriate correction factors that could be applied to experimental measurements. It was found that in small fields, the air cavity of these custom-made research chambers perturbed the secondary electron fluence profile significantly, resulting in decreased fluence within the active volume, which in turn produces a chamber under-response. It is demonstrated that a large correction to the p(fl) correction factor would be required to improve dosimetric accuracy in small fields, and that these factors could be derived using Monte Carlo simulations.

  1. Stability of A-150 plastic ionization chamber response over a ~30 year period

    SciTech Connect

    Kroc, Thomas K.; Lennox, Arlene J.; /Fermilab

    2007-08-01

    At the NIU Institute for Neutron Therapy at Fermilab, the clinical tissue-equivalent ionization chamber response is measured every treatment day using a cesium source that was configured to match readings obtained at the National Bureau of Standards. Daily measurements are performed in air using the air-to-tissue dose conversion factors given in AAPM Report no. 7. The measured exposure calibration factors have been tabulated and graphed as a function of time from 1978 to present. For A-150 plastic ionization chambers, these factors exhibit a sinusoidal variation with a period of approximately one year and amplitude of {+-} 1%. This variation, attributable to the hygroscopic nature of A-150 plastic, is correlated with the relative humidity of the facility, and is greater than the humidity corrections for gas described in the literature. Our data suggest that chamber calibration should be performed at least weekly to accommodate these variations.

  2. Physical and chemical analysis of lithium-ion battery cell-to-cell failure events inside custom fire chamber

    NASA Astrophysics Data System (ADS)

    Spinner, Neil S.; Field, Christopher R.; Hammond, Mark H.; Williams, Bradley A.; Myers, Kristina M.; Lubrano, Adam L.; Rose-Pehrsson, Susan L.; Tuttle, Steven G.

    2015-04-01

    A 5-cubic meter decompression chamber was re-purposed as a fire test chamber to conduct failure and abuse experiments on lithium-ion batteries. Various modifications were performed to enable remote control and monitoring of chamber functions, along with collection of data from instrumentation during tests including high speed and infrared cameras, a Fourier transform infrared spectrometer, real-time gas analyzers, and compact reconfigurable input and output devices. Single- and multi-cell packages of LiCoO2 chemistry 18650 lithium-ion batteries were constructed and data was obtained and analyzed for abuse and failure tests. Surrogate 18650 cells were designed and fabricated for multi-cell packages that mimicked the thermal behavior of real cells without using any active components, enabling internal temperature monitoring of cells adjacent to the active cell undergoing failure. Heat propagation and video recordings before, during, and after energetic failure events revealed a high degree of heterogeneity; some batteries exhibited short burst of sparks while others experienced a longer, sustained flame during failure. Carbon monoxide, carbon dioxide, methane, dimethyl carbonate, and ethylene carbonate were detected via gas analysis, and the presence of these species was consistent throughout all failure events. These results highlight the inherent danger in large format lithium-ion battery packs with regards to cell-to-cell failure, and illustrate the need for effective safety features.

  3. Monte Carlo-based correction factors for ion chamber dosimetry in heterogeneous phantoms for megavoltage photon beams.

    PubMed

    Araki, Fujio

    2012-11-21

    The purpose of this study was to investigate the perturbation correction factors and inhomogeneity correction factors (ICFs) for a thin-walled cylindrical ion chamber in a heterogeneous phantom including solid water, lung and bone plastic materials. The perturbation factors due to the replacement of the air cavity, non-water equivalence of the wall and the stem, non-air equivalence of the central electrode and the overall perturbation factor, P(Q), for a cylindrical chamber, in the heterogeneous phantom were calculated with the EGSnrc/Cavity Monte Carlo code for 6 and 15 MV photon beams. The PTW31010 (0.125 cm(3)) chamber was modeled with Monte Carlo simulations, and was used for measurements and calculations of percentage depth ionization (PDI) or percentage depth dose (PDD). ICFs were calculated from the ratio of the product of the stopping power ratios (SPRs) and P(Q) of lung or bone to solid water. Finally, the measured PDIs were converted to PDDs by using ICFs and were compared with those calculated by the Monte Carlo method. The perturbation effect for the ion chamber in lung material is insignificant at 5 × 5 and 10 × 10 cm(2) fields, but the effect needs to be considered under conditions of lateral electron disequilibrium with a 3 × 3 cm(2) field. ICFs in lung varied up to 2% and 4% depending on the field size for 6 and 15 MV, respectively. For bone material, the perturbation effects due to the chamber wall and the stem were more significant at up to 3.5% and 1.6% for 6 MV, respectively. ICFs for bone material were approximately 0.945 and 0.940 for 6 and 15 MV, respectively. The converted PDDs by using ICFs were in good agreement with Monte Carlo calculated PDDs. The chamber perturbation correction and SPRs should strictly be considered for ion chamber dosimetry in heterogeneous media. This is more important for small field dosimetry in lung and bone materials.

  4. The effect of ambient pressure on well chamber response: Monte Carlo calculated results for the HDR 1000 plus.

    PubMed

    Bohm, Tim D; Griffin, Sheridan L; DeLuca, Paul M; DeWerd, Larry A

    2005-04-01

    The determination of the air kerma strength of a brachytherapy seed is necessary for effective treatment planning. Well ionization chambers are used on site at therapy clinics to determine the air kerma strength of seeds. In this work, the response of the Standard Imaging HDR 1000 Plus well chamber to ambient pressure is examined using Monte Carlo calculations. The experimental work examining the response of this chamber as well as other chambers is presented in a companion paper. The Monte Carlo results show that for low-energy photon sources, the application of the standard temperature pressure PTP correction factor produces an over-response at the reduced air densities/pressures corresponding to high elevations. With photon sources of 20 to 40 keV, the normalized PTP corrected chamber response is as much as 10% to 20% over unity for air densities/pressures corresponding to an elevation of 3048 m (10000 ft) above sea level. At air densities corresponding to an elevation of 1524 m (5000 ft), the normalized PTP-corrected chamber response is 5% to 10% over unity for these photon sources. With higher-energy photon sources (>100 keV), the normalized PTP corrected chamber response is near unity. For low-energy beta sources of 0.25 to 0.50 MeV, the normalized PTP-corrected chamber response is as much as 4% to 12% over unity for air densities/pressures corresponding to an elevation of 3048 m (10000 ft) above sea level. Higher-energy beta sources (>0.75 MeV) have a normalized PTP corrected chamber response near unity. Comparing calculated and measured chamber responses for common 103Pd- and 125I-based brachytherapy seeds show agreement to within 2.7% and 1.9%, respectively. Comparing MCNP calculated chamber responses with EGSnrc calculated chamber responses show agreement to within 3.1% at photon energies of 20 to 40 keV. We conclude that Monte Carlo transport calculations accurately model the response of this well chamber. Further, applying the standard PTP correction

  5. Technical Note: Influence of Compton currents on profile measurements in small-volume ion chambers

    SciTech Connect

    Tanny, Sean; Sperling, Nicholas; Parsai, E. Ishmael; Holmes, Shannon

    2015-10-15

    Purpose: This work is to evaluate the effects of Compton current generation in three small-volume ionization chambers on measured beam characteristics for electron fields. Methods: Beam scans were performed using Exradin A16, A26, and PTW 31014 microchambers. Scans with varying chamber components shielded were performed. Static point measurements, output factors, and cable only irradiations were performed to determine the contribution of Compton currents to various components of the chamber. Monte Carlo simulations were performed to evaluate why one microchamber showed a significant reduction in Compton current generation. Results: Beam profiles demonstrated significant distortion for two of the three chambers when scanned parallel to the chamber axis, produced by electron deposition within the wire. Measurements of ionization produced within the cable identified Compton current generation as the cause of these distortions. The size of the central collecting wire was found to have the greatest influence on the magnitude of Compton current generation. Conclusions: Microchambers can demonstrate significant (>5%) deviations from properties as measured with larger volume chambers (0.125 cm{sup 3} and above). These deviations can be substantially reduced by averaging measurements conducted at opposite polarities.

  6. A combined segmented anode gas ionization chamber and time-of-flight detector for heavy ion elastic recoil detection analysis

    NASA Astrophysics Data System (ADS)

    Ström, Petter; Petersson, Per; Rubel, Marek; Possnert, Göran

    2016-10-01

    A dedicated detector system for heavy ion elastic recoil detection analysis at the Tandem Laboratory of Uppsala University is presented. Benefits of combining a time-of-flight measurement with a segmented anode gas ionization chamber are demonstrated. The capability of ion species identification is improved with the present system, compared to that obtained when using a single solid state silicon detector for the full ion energy signal. The system enables separation of light elements, up to Neon, based on atomic number while signals from heavy elements such as molybdenum and tungsten are separated based on mass, to a sample depth on the order of 1 μm. The performance of the system is discussed and a selection of material analysis applications is given. Plasma-facing materials from fusion experiments, in particular metal mirrors, are used as a main example for the discussion. Marker experiments using nitrogen-15 or oxygen-18 are specific cases for which the described improved species separation and sensitivity are required. Resilience to radiation damage and significantly improved energy resolution for heavy elements at low energies are additional benefits of the gas ionization chamber over a solid state detector based system.

  7. A TPC (Time Projection Chamber) detector for the study of high multiplicity heavy ion collisions

    SciTech Connect

    Rai, G.; Arthur, A.; Bieser, F.; Harnden, C.W.; Jones, R.; Klienfelder, S.; Lee, K.; Matis, H.S.; Nakamura, M.; McParland, C.; Nesbitt, D.; Odyniec, G.; Olson, D.; Pugh, H.G.; Ritter, H.G.; Symons, T.J.M.; Wieman, H.; Wright, M.; Wright, R. ); Rudge, A. )

    1990-01-01

    The design of a Time Projection Chamber (TPC) detector with complete pad coverage is presented. The TPC will allow the measurements of high multiplicity ({approx} 200 tracks) relativistic nucleus-nucleus collisions initiated with the heaviest, most energetic projectiles available at the LBL BEVALAC accelerator facility. The front end electronics, composed of over 15,000 time sampling channels, will be located on the chamber. The highly integrated, custom designed, electronics and the VME based data acquisition system are described. 10 refs., 8 figs., 1 tab.

  8. The Chamber for Studying Rice Response to Elevated Nighttime Temperature in Field

    PubMed Central

    Chen, Song; Zheng, Xi; Wang, Dangying; Xu, Chunmei; Laza, Ma. Rebecca C.; Zhang, Xiufu

    2013-01-01

    An in situ temperature-controlled field chamber was developed for studying a large population of rice plant under different nighttime temperature treatments while maintaining conditions similar to those in the field during daytime. The system consists of a pipe hoop shed-type chamber with manually removable covers manipulated to provide a natural environment at daytime and a relatively stable and accurate temperature at night. Average air temperatures of 22.4 ± 0.3°C at setting of 22°C, 27.6 ± 0.4°C at 27°C, and 23.8 ± 0.7°C ambient conditions were maintained with the system. No significant horizontal and vertical differences in temperature were found and only slight changes in water temperatures were observed between the chambers and ambient conditions at 36 days after transplanting. A slight variation in CO2 concentration was observed at the end of the treatment during the day, but the 10-μmol CO2 mol−1 difference was too small to alter plant response. The present utilitarian system, which only utilizes an air conditioner/heater, is suitable for studying the effect of nighttime temperature on plant physiological responses with minimal perturbation of other environmental factors. At the same time, it will enable in situ screening of many rice genotypes. PMID:24089603

  9. Modeling of life limiting phenomena in the discharge chamber of an electron bombardment ion thruster

    NASA Technical Reports Server (NTRS)

    Handoo, Arvind K.; Ray, Pradosh K.

    1991-01-01

    An experimental facility to study the low energy sputtering of metal surfaces with ions produced by an ion gun is described. The energy of the ions ranged from 10 to 500 eV. Cesium ions with energies from 100 to 500 eV were used initially to characterize the operation of the ion gun. Next, argon and xenon ions were used to measure the sputtering yields of cobalt (Co), Cadmium (Cd), and Chromium (Cr) at an operating temperature of 2x10(exp -5) Torr. The ion current ranged from 0.0135 micro-A at 500 eV. The targets were electroplated on a copper substrate. The surface density of the electroplated material was approx. 50 micro-g/sq cm. The sputtered atoms were collected on an aluminum foil surrounding the target. Radioactive tracers were used to measure the sputtering yields. The sputtering yields of Cr were found to be much higher than those of Co and Cd. The yields of Co and Cd were comparable, with Co providing the higher yields. Co and Cd targets were observed to sputter at energies as low as 10 eV for both argon and xenon ions. The Cr yields could not be measured below 20 eV for argon ions and 15 eV for xenon ions. On a linear scale the yield energy curves near the threshold energies exhibit a concave nature.

  10. Signal generator exciting an electromagnetic field for ion beam transport to the vacuum chamber of a mass spectrometer

    NASA Astrophysics Data System (ADS)

    Tubol'tsev, Yu. V.; Kogan, V. T.; Bogdanov, A. A.; Chichagov, Yu. V.; Antonov, A. S.

    2015-02-01

    A high-voltage high-frequency signal generator is described that excites an electric field for ion beam transport from an ion source to the vacuum chamber of a mass spectrometer. Excitation signals to the number of two are high-frequency sine-wave out-of-phase signals with the same amplitudes. The amplitude and phase of the signals vary from 20 to 100 V and from 10 kHz to 1 MHz, respectively. The generator also produces a controlled bias voltage in the interval 50-200 V. The frequency and amplitude of the signals, as well as the bias voltage, are computer-controlled via the USB interface.

  11. Direct determination of k Q for Farmer-type ionization chambers in a clinical scanned carbon ion beam using water calorimetry.

    PubMed

    Osinga-Blättermann, J-M; Brons, S; Greilich, S; Jäkel, O; Krauss, A

    2017-03-21

    Until now, the dosimetry of carbon ions with ionization chambers has not reached the same level of accuracy as that of high-energy photons. This is mainly caused by the approximately threefold larger uncertainty of the k Q factor of ionization chambers, which, due to the lack of experimental data, is still derived by calculations. Measurements of absorbed dose to water, D w, by means of water calorimetry have now been performed in the entrance channel of a scanned 6 cm  ×  6 cm radiation field of 429 MeV/u carbon ions, allowing the direct calibration of ionization chambers and thus the experimental determination of k Q. Within this work, values for k Q have been determined for the Farmer-type ionization chambers FC65-G and TM30013. A detailed investigation of the radiation field enabled the accurate determination of correction factors needed for both calorimetric and ionometric measurements. Finally, a relative standard measurement uncertainty of 0.8% (k  =  1) could be achieved for the experimental k Q values. For both chambers, the experimental k Q factors were found to be about 1% larger than those tabulated in the German DIN 6801-1 protocol, whereas compared to the theoretical values stated in the TRS-398 protocol, the experimental k Q value agrees within 0.4% for the TM30013 chamber but is about 1% lower in the case of the FC65-G chamber.

  12. Direct determination of k Q for Farmer-type ionization chambers in a clinical scanned carbon ion beam using water calorimetry

    NASA Astrophysics Data System (ADS)

    Osinga-Blättermann, J.-M.; Brons, S.; Greilich, S.; Jäkel, O.; Krauss, A.

    2017-03-01

    Until now, the dosimetry of carbon ions with ionization chambers has not reached the same level of accuracy as that of high-energy photons. This is mainly caused by the approximately threefold larger uncertainty of the k Q factor of ionization chambers, which, due to the lack of experimental data, is still derived by calculations. Measurements of absorbed dose to water, D w, by means of water calorimetry have now been performed in the entrance channel of a scanned 6 cm  ×  6 cm radiation field of 429 MeV/u carbon ions, allowing the direct calibration of ionization chambers and thus the experimental determination of k Q. Within this work, values for k Q have been determined for the Farmer-type ionization chambers FC65-G and TM30013. A detailed investigation of the radiation field enabled the accurate determination of correction factors needed for both calorimetric and ionometric measurements. Finally, a relative standard measurement uncertainty of 0.8% (k  =  1) could be achieved for the experimental k Q values. For both chambers, the experimental k Q factors were found to be about 1% larger than those tabulated in the German DIN 6801-1 protocol, whereas compared to the theoretical values stated in the TRS-398 protocol, the experimental k Q value agrees within 0.4% for the TM30013 chamber but is about 1% lower in the case of the FC65-G chamber.

  13. Sputter erosion and deposition in the discharge chamber of a small mercury ion thruster

    NASA Technical Reports Server (NTRS)

    Power, J. L.

    1973-01-01

    A 5-cm diameter mercury ion thruster similar to one tested for 9715 hours was operated approximately 400 hrs each at discharge voltages of 36.6, 39.6, and 42.6 V, with corresponding discharge propellant utilizations of 58, 68, and 70 percent. The observed sputter erosion rates of the internal thruster parts and the anode weight gain rate all rose rapidly with discharge voltage and were roughly in the ratio of 1:3:5 for the three voltages. The combined weight loss of the internal thruster parts nearly balanced the anode weight gain. Hg+2 ions apparently caused most of the observed erosion.

  14. Sputter erosion and deposition in the discharge chamber of a small mercury ion thruster

    NASA Technical Reports Server (NTRS)

    Power, J. L.

    1973-01-01

    A 5 cm diameter mercury ion thruster similar to one tested for 9715 hours was operated approximately 400 hrs each at discharge voltages of 36.6, 39.6, and 42.6 V, with corresponding discharge propellant utilizations of 58, 68, and 70 percent. The observed sputter erosion rates of the internal thruster parts and the anode weight gain rate all rose rapidly with discharge voltage and were roughly in the ratio of 1:3:5 for the three voltages. The combined weight loss of the internal thruster parts nearly balanced the anode weight gain. Hg(+2) ion apparently caused most of the observed erosion.

  15. Verification of patient-specific dose distributions in proton therapy using a commercial two-dimensional ion chamber array

    SciTech Connect

    Arjomandy, Bijan; Sahoo, Narayan; Ciangaru, George; Zhu, Ronald; Song Xiaofei; Gillin, Michael

    2010-11-15

    Purpose: The purpose of this study was to determine whether a two-dimensional (2D) ion chamber array detector quickly and accurately measures patient-specific dose distributions in treatment with passively scattered and spot scanning proton beams. Methods: The 2D ion chamber array detector MatriXX was used to measure the dose distributions in plastic water phantom from passively scattered and spot scanning proton beam fields planned for patient treatment. Planar dose distributions were measured using MatriXX, and the distributions were compared to those calculated using a treatment-planning system. The dose distributions generated by the treatment-planning system and a film dosimetry system were similarly compared. Results: For passively scattered proton beams, the gamma index for the dose-distribution comparison for treatment fields for three patients with prostate cancer and for one patient with lung cancer was less than 1.0 for 99% and 100% of pixels for a 3% dose tolerance and 3 mm distance-to-dose agreement, respectively. For spot scanning beams, the mean ({+-} standard deviation) percentages of pixels with gamma indices meeting the passing criteria were 97.1%{+-}1.4% and 98.8%{+-}1.4% for MatriXX and film dosimetry, respectively, for 20 fields used to treat patients with prostate cancer. Conclusions: Unlike film dosimetry, MatriXX provides not only 2D dose-distribution information but also absolute dosimetry in fractions of minutes with acceptable accuracy. The results of this study indicate that MatriXX can be used to verify patient-field specific dose distributions in proton therapy.

  16. SU-E-T-392: Evaluation of Ion Chamber/film and Log File Based QA to Detect Delivery Errors

    SciTech Connect

    Nelson, C; Mason, B; Kirsner, S; Ohrt, J

    2015-06-15

    Purpose: Ion chamber and film (ICAF) is a method used to verify patient dose prior to treatment. More recently, log file based QA has been shown as an alternative for measurement based QA. In this study, we delivered VMAT plans with and without errors to determine if ICAF and/or log file based QA was able to detect the errors. Methods: Using two VMAT patients, the original treatment plan plus 7 additional plans with delivery errors introduced were generated and delivered. The erroneous plans had gantry, collimator, MLC, gantry and collimator, collimator and MLC, MLC and gantry, and gantry, collimator, and MLC errors. The gantry and collimator errors were off by 4{sup 0} for one of the two arcs. The MLC error introduced was one in which the opening aperture didn’t move throughout the delivery of the field. For each delivery, an ICAF measurement was made as well as a dose comparison based upon log files. Passing criteria to evaluate the plans were ion chamber less and 5% and film 90% of pixels pass the 3mm/3% gamma analysis(GA). For log file analysis 90% of voxels pass the 3mm/3% 3D GA and beam parameters match what was in the plan. Results: Two original plans were delivered and passed both ICAF and log file base QA. Both ICAF and log file QA met the dosimetry criteria on 4 of the 12 erroneous cases analyzed (2 cases were not analyzed). For the log file analysis, all 12 erroneous plans alerted a mismatch in delivery versus what was planned. The 8 plans that didn’t meet criteria all had MLC errors. Conclusion: Our study demonstrates that log file based pre-treatment QA was able to detect small errors that may not be detected using an ICAF and both methods of were able to detect larger delivery errors.

  17. An ion thruster internal discharge chamber electrostatic probe diagnostic technique using a high-speed probe positioning system.

    PubMed

    Herman, Daniel A; Gallimore, Alec D

    2008-01-01

    Extensive resources have been allocated to diagnose and minimize lifetime-limiting factors in gridded ion thrusters. While most of this effort has focused on grid erosion, results from wear tests indicate that discharge cathode erosion may also play an important role in limiting the lifetime of ring-cusp ion thrusters proposed for future large flagship missions. The detailed characterization of the near-cathode discharge plasma is essential for mitigating discharge cathode erosion. However, severe difficulty is encountered when attempting to measure internal discharge plasma parameters during thruster operation with conventional probing techniques. These difficulties stem from the high-voltage, high-density discharge cathode plume, which is a hostile environment for probes. A method for interrogating the discharge chamber plasma of a working ion thruster over a two-dimensional grid is demonstrated. The high-speed axial reciprocating probe positioning system is used to minimize thruster perturbation during probe insertion and to reduce heating of the probe. Electrostatic probe measurements from a symmetric double Langmuir probe are presented over a two-dimensional spatial array in the near-discharge cathode assembly region of a 30-cm-diameter ring-cusp ion thruster. Electron temperatures, 2-5 eV, and number density contours, with a maximum of 8 x 10(12) cm(-3) on centerline, are measured. These data provide detailed electron temperature and number density contours which, when combined with plasma potential measurements, may shed light on discharge cathode erosion processes and the effect of thruster operating conditions on erosion rates.

  18. Design and Installation of a Field Ionization Test Chamber for Ion Thrusters

    DTIC Science & Technology

    2011-12-01

    Romano Second Reader: Oscar Biblarz THIS PAGE INTENTIONALLY LEFT BLANK i REPORT DOCUMENTATION PAGE Form Approved OMB No. 0704–0188 Public...Paul W. Camp Approved by: Sebastian Osswald Thesis Advisor Marcello Romano Thesis Co-Advisor Oscar Biblarz Second Reader Knox T...in its success. I would also like to thank Professor Oscar Biblarz, for his wealth of knowledge on ion propulsion he imparted to me. A special

  19. Thermal characteristics of air flow cooling in the lithium ion batteries experimental chamber

    SciTech Connect

    Lukhanin A.; Rohatgi U.; Belyaev, A.; Fedorchenko, D.; Khazhmuradov, M.; Lukhanin, O; Rudychev, I.

    2012-07-08

    A battery pack prototype has been designed and built to evaluate various air cooling concepts for the thermal management of Li-ion batteries. The heat generation from the Li-Ion batteries was simulated with electrical heat generation devices with the same dimensions as the Li-Ion battery (200 mm x 150 mm x 12 mm). Each battery simulator generates up to 15W of heat. There are 20 temperature probes placed uniformly on the surface of the battery simulator, which can measure temperatures in the range from -40 C to +120 C. The prototype for the pack has up to 100 battery simulators and temperature probes are recorder using a PC based DAQ system. We can measure the average surface temperature of the simulator, temperature distribution on each surface and temperature distributions in the pack. The pack which holds the battery simulators is built as a crate, with adjustable gap (varies from 2mm to 5mm) between the simulators for air flow channel studies. The total system flow rate and the inlet flow temperature are controlled during the test. The cooling channel with various heat transfer enhancing devices can be installed between the simulators to investigate the cooling performance. The prototype was designed to configure the number of cooling channels from one to hundred Li-ion battery simulators. The pack is thermally isolated which prevents heat transfer from the pack to the surroundings. The flow device can provide the air flow rate in the gap of up to 5m/s velocity and air temperature in the range from -30 C to +50 C. Test results are compared with computational modeling of the test configurations. The present test set up will be used for future tests for developing and validating new cooling concepts such as surface conditions or heat pipes.

  20. Super-resolution non-parametric deconvolution in modelling the radial response function of a parallel plate ionization chamber.

    PubMed

    Kulmala, A; Tenhunen, M

    2012-11-07

    The signal of the dosimetric detector is generally dependent on the shape and size of the sensitive volume of the detector. In order to optimize the performance of the detector and reliability of the output signal the effect of the detector size should be corrected or, at least, taken into account. The response of the detector can be modelled using the convolution theorem that connects the system input (actual dose), output (measured result) and the effect of the detector (response function) by a linear convolution operator. We have developed the super-resolution and non-parametric deconvolution method for determination of the cylinder symmetric ionization chamber radial response function. We have demonstrated that the presented deconvolution method is able to determine the radial response for the Roos parallel plate ionization chamber with a better than 0.5 mm correspondence with the physical measures of the chamber. In addition, the performance of the method was proved by the excellent agreement between the output factors of the stereotactic conical collimators (4-20 mm diameter) measured by the Roos chamber, where the detector size is larger than the measured field, and the reference detector (diode). The presented deconvolution method has a potential in providing reference data for more accurate physical models of the ionization chamber as well as for improving and enhancing the performance of the detectors in specific dosimetric problems.

  1. Ion-driver fast ignition: Reducing heavy-ion fusion driver energy and cost, simplifying chamber design, target fab, tritium fueling and power conversion

    SciTech Connect

    Logan, G.; Callahan-Miller, D.; Perkins, J.; Caporaso, G.; Tabak, M.; Moir, R.; Meier, W.; Bangerter, Roger; Lee, Ed

    1998-04-01

    Ion fast ignition, like laser fast ignition, can potentially reduce driver energy for high target gain by an order of magnitude, while reducing fuel capsule implosion velocity, convergence ratio, and required precisions in target fabrication and illumination symmetry, all of which should further improve and simplify IFE power plants. From fast-ignition target requirements, we determine requirements for ion beam acceleration, pulse-compression, and final focus for advanced accelerators that must be developed for much shorter pulses and higher voltage gradients than today's accelerators, to deliver the petawatt peak powers and small focal spots ({approx}100 {micro}m) required. Although such peak powers and small focal spots are available today with lasers, development of such advanced accelerators is motivated by the greater likely efficiency of deep ion penetration and deposition into pre-compressed 1000x liquid density DT cores. Ion ignitor beam parameters for acceleration, pulse compression, and final focus are estimated for two examples based on a Dielectric Wall Accelerator; (1) a small target with {rho}r {approx} 2 g/cm{sup 2} for a small demo/pilot plant producing {approx}40 MJ of fusion yield per target, and (2) a large target with {rho}r {approx} 10 g/cm{sup 2} producing {approx}1 GJ yield for multi-unit electricity/hydrogen plants, allowing internal T-breeding with low T/D ratios, >75 % of the total fusion yield captured for plasma direct conversion, and simple liquid-protected chambers with gravity clearing. Key enabling development needs for ion fast ignition are found to be (1) ''Close-coupled'' target designs for single-ended illumination of both compressor and ignitor beams; (2) Development of high gradient (>25 MV/m) linacs with high charge-state (q {approx} 26) ion sources for short ({approx}5 ns) accelerator output pulses; (3) Small mm-scale laser-driven plasma lens of {approx}10 MG fields to provide steep focusing angles close-in to the target

  2. Discharge Chamber Plasma Structure of a 30-cm NSTAR-Type Ion Engine

    NASA Technical Reports Server (NTRS)

    Herman, Daniel A.; Gallimore, Alec D.

    2006-01-01

    Single Langmuir probe measurements are presented over a two-dimensional array of locations in the near Discharge Cathode Assembly (DCA) region of a 30-cm diameter ring cusp ion thruster over a range of thruster operating conditions encompassing the high-power half of the NASA throttling table. The Langmuir probe data were analyzed with two separate methods. All data were analyzed initially assuming an electron population consisting of Maxwellian electrons only. The on-axis data were then analyzed assuming both Maxwellian and primary electrons. Discharge plasma data taken with beam extraction exhibit a broadening of the higher electron temperature plume boundary compared to similar discharge conditions without beam extraction. The opposite effect is evident with the electron/ion number density as the data without began, extraction appears to be more collimated than the corresponding data with beam extraction. Primary electron energy and number densities are presented for one operating condition giving an order of magnitude of their value and the error associated with this calculation.

  3. Insulated Conducting Cantilevered Nanotips and Two-Chamber Recording System for High Resolution Ion Sensing AFM

    PubMed Central

    Meckes, Brian; Arce, Fernando Teran; Connelly, Laura S.; Lal, Ratnesh

    2014-01-01

    Biological membranes contain ion channels, which are nanoscale pores allowing controlled ionic transport and mediating key biological functions underlying normal/abnormal living. Synthetic membranes with defined pores are being developed to control various processes, including filtration of pollutants, charge transport for energy storage, and separation of fluids and molecules. Although ionic transport (currents) can be measured with single channel resolution, imaging their structure and ionic currents simultaneously is difficult. Atomic force microscopy enables high resolution imaging of nanoscale structures and can be modified to measure ionic currents simultaneously. Moreover, the ionic currents can also be used to image structures. A simple method for fabricating conducting AFM cantilevers to image pore structures at high resolution is reported. Tungsten microwires with nanoscale tips are insulated except at the apex. This allows simultaneous imaging via cantilever deflections in normal AFM force feedback mode as well as measuring localized ionic currents. These novel probes measure ionic currents as small as picoampere while providing nanoscale spatial resolution surface topography and is suitable for measuring ionic currents and conductance of biological ion channels. PMID:24663394

  4. Variation of spectral response curves of GaAs photocathodes in activation chamber

    NASA Astrophysics Data System (ADS)

    Zou, Jijun; Chang, Benkang; Yang, Zhi; Wang, Hui; Gao, Pin

    2006-09-01

    The spectral response curves of reflection-mode GaAs (100) photocathodes are measured in activation chamber by multi-information measurement system at RT, and by applying quantum efficiency formula, the variation of spectral response curves have been studied. Reflection-mode GaAs photocathodes materials are grown over GaAs wafer (100) by MBE with p-type beryllium doping, doping concentration is 1×10 19 cm -3 and the active layer thickness is 1.6μm. During the high-temperature activation process, the spectral response curves varied with activation time are measured. After the low-temperature activation, the photocathode is illuminated by a white light source, and the spectral response curves varied with illumination time are measured every other hour. Experimental results of both high-temperature and low-temperature activations show that the spectral response curve shape of photocathodes is a function of time. We use traditional quantum efficiency formulas of photocathodes, in which only the Γ photoemission is considered, to fit experimental spectral response curves, and find the theoretical curves are not in agreement with the experimental curves, the reason is other valley and hot-electron yields are necessary to be included in yields of reflection-mode photocathodes. Based on the two-minima diffusion model and the fit of escape probability, we modified the quantum efficiency formula of reflection-mode photocathodes, the modified formula can be used to explain the variation of yield curves of reflection-mode photocathodes very well.

  5. A 2D ion chamber array audit of wedged and asymmetric fields in an inhomogeneous lung phantom

    SciTech Connect

    Lye, Jessica; Dunn, Leon Alves, Andrew; Kenny, John; Lehmann, Joerg; Williams, Ivan; Kron, Tomas; Cole, Andrew

    2014-10-15

    Purpose: The Australian Clinical Dosimetry Service (ACDS) has implemented a new method of a nonreference condition Level II type dosimetric audit of radiotherapy services to increase measurement accuracy and patient safety within Australia. The aim of this work is to describe the methodology, tolerances, and outcomes from the new audit. Methods: The ACDS Level II audit measures the dose delivered in 2D planes using an ionization chamber based array positioned at multiple depths. Measurements are made in rectilinear homogeneous and inhomogeneous phantoms composed of slabs of solid water and lung. Computer generated computed tomography data sets of the rectilinear phantoms are supplied to the facility prior to audit for planning of a range of cases including reference fields, asymmetric fields, and wedged fields. The audit assesses 3D planning with 6 MV photons with a static (zero degree) gantry. Scoring is performed using local dose differences between the planned and measured dose within 80% of the field width. The overall audit result is determined by the maximum dose difference over all scoring points, cases, and planes. Pass (Optimal Level) is defined as maximum dose difference ≤3.3%, Pass (Action Level) is ≤5.0%, and Fail (Out of Tolerance) is >5.0%. Results: At close of 2013, the ACDS had performed 24 Level II audits. 63% of the audits passed, 33% failed, and the remaining audit was not assessable. Of the 15 audits that passed, 3 were at Pass (Action Level). The high fail rate is largely due to a systemic issue with modeling asymmetric 60° wedges which caused a delivered overdose of 5%–8%. Conclusions: The ACDS has implemented a nonreference condition Level II type audit, based on ion chamber 2D array measurements in an inhomogeneous slab phantom. The powerful diagnostic ability of this audit has allowed the ACDS to rigorously test the treatment planning systems implemented in Australian radiotherapy facilities. Recommendations from audits have led to

  6. SU-F-BRA-08: An Investigation of Well-Chamber Responses for An Electronic Brachytherapy Source

    SciTech Connect

    Culberson, W; Micka, J

    2015-06-15

    Purpose: The aim of this study was to investigate the variation of well-type ionization chamber response between a Xoft Axxent™ electronic brachytherapy (EBT) source and a GE Oncoseed™ 6711 I-125 seed. Methods: A new EBT air-kerma standard has recently been introduced by the National Institute of Standards and Technology (NIST). Historically, the Axxent source strength has been based on a well chamber calibration from an I-125 brachytherapy source due to the lack of a primary standard. Xoft utilizes a calibration procedure that employs a GE 6711 seed calibration as a surrogate standard to represent the air-kerma strength of an Axxent source. This method is based on the premise that the energies of the two sources are similar and thus, a conversion factor would be a suitable interim solution until a NIST standard was established. For this investigation, a number of well chambers of the same model type and three different EBT sources were used to determine NIST-traceable calibration coefficients for both the GE 6711 seed and the Axxent source. The ratio of the two coefficients was analyzed for consistency and also to identify any possible correlations with chamber vintage or the sources themselves. Results: For all well chambers studied, the relative standard deviation of the ratio of calibration coefficients between the two standards is less than 1%. No specific trends were found with the well chamber vintage or between the three different EBT sources used. Conclusion: The variation of well chamber calibration coefficients between a Xoft Axxent™ EBT source versus a GE 6711 Oncoseed™ are consistent across well chamber vintage and between sources. The results of this investigation confirm the underlying assumptions and stability of the surrogate standard currently in use by Xoft, and establishes a migration path for future implementation of the new NIST air kerma standard. This research is supported in part by Xoft, a subsidiary of iCAD.

  7. Dose-response of EBT3 radiochromic films to proton and carbon ion clinical beams.

    PubMed

    Castriconi, Roberta; Ciocca, Mario; Mirandola, Alfredo; Sini, Carla; Broggi, Sara; Schwarz, Marco; Fracchiolla, Francesco; Martišíková, Mária; Aricò, Giulia; Mettivier, Giovanni; Russo, Paolo

    2017-01-21

    We investigated the dose-response of the external beam therapy 3 (EBT3) films for proton and carbon ion clinical beams, in comparison with conventional radiotherapy beams; we also measured the film response along the energy deposition-curve in water. We performed measurements at three hadrontherapy centres by delivering monoenergetic pencil beams (protons: 63-230 MeV; carbon ions: 115-400 MeV/u), at 0.4-20 Gy dose to water, in the plateau of the depth-dose curve. We also irradiated the films to clinical MV-photon and electron beams. We placed the EBT3 films in water along the whole depth-dose curve for 148.8 MeV protons and 398.9 MeV/u carbon ions, in comparison with measurements provided by a plane-parallel ionization chamber. For protons, the response of EBT3 in the plateau of the depth-dose curve is not different from that of photons, within experimental uncertainties. For carbon ions, we observed an energy dependent under-response of EBT3 film, from 16% to 29% with respect to photon beams. Moreover, we observed an under-response in the Bragg peak region of about 10% for 148.8 MeV protons and of about 42% for 398.9 MeV/u carbon ions. For proton and carbon ion clinical beams, an under-response occurs at the Bragg peak. For carbon ions, we also observed an under-response of the EBT3 in the plateau of the depth-dose curve. This effect is the highest at the lowest initial energy of the clinical beams, a phenomenon related to the corresponding higher LET in the film sensitive layer. This behavior should be properly modeled when using EBT3 films for accurate 3D dosimetry.

  8. Dose-response of EBT3 radiochromic films to proton and carbon ion clinical beams

    NASA Astrophysics Data System (ADS)

    Castriconi, Roberta; Ciocca, Mario; Mirandola, Alfredo; Sini, Carla; Broggi, Sara; Schwarz, Marco; Fracchiolla, Francesco; Martišíková, Mária; Aricò, Giulia; Mettivier, Giovanni; Russo, Paolo

    2017-01-01

    We investigated the dose-response of the external beam therapy 3 (EBT3) films for proton and carbon ion clinical beams, in comparison with conventional radiotherapy beams; we also measured the film response along the energy deposition-curve in water. We performed measurements at three hadrontherapy centres by delivering monoenergetic pencil beams (protons: 63-230 MeV; carbon ions: 115-400 MeV/u), at 0.4-20 Gy dose to water, in the plateau of the depth-dose curve. We also irradiated the films to clinical MV-photon and electron beams. We placed the EBT3 films in water along the whole depth-dose curve for 148.8 MeV protons and 398.9 MeV/u carbon ions, in comparison with measurements provided by a plane-parallel ionization chamber. For protons, the response of EBT3 in the plateau of the depth-dose curve is not different from that of photons, within experimental uncertainties. For carbon ions, we observed an energy dependent under-response of EBT3 film, from 16% to 29% with respect to photon beams. Moreover, we observed an under-response in the Bragg peak region of about 10% for 148.8 MeV protons and of about 42% for 398.9 MeV/u carbon ions. For proton and carbon ion clinical beams, an under-response occurs at the Bragg peak. For carbon ions, we also observed an under-response of the EBT3 in the plateau of the depth-dose curve. This effect is the highest at the lowest initial energy of the clinical beams, a phenomenon related to the corresponding higher LET in the film sensitive layer. This behavior should be properly modeled when using EBT3 films for accurate 3D dosimetry.

  9. Heavy ion beam degradation from stripping in near vacuum reactor chambers

    SciTech Connect

    Barletta, W.A.

    1981-07-21

    With the use of a particle simulation code we have investigated the ballistic transport of heavy ion beams through a gas-filled reactor for inertial confinement fusion. The background gas pressure has been taken to be 10/sup -4/ torr - 10/sup -3/ torr of Lithium vapor as is appropriate to the HYLIFE reactor concept. During transport to the pellet, Coulomb collisions of beam particles with the background gas will convert a fraction of the beam to charges states higher than the initial value. Collisons will also produce an associated swarm of knock-on electrons. As the beam approaches the pellet, anharmonic components of the space charges forces will lead to a distortion of the phase space of the beam and a consequent degradation of the focal properties of the beam. This degradation can be described in terms of an increase in the rms emittance of the beam. The degree of emittance growth depends sensitivity upon the initial spatial distribution of particles in the beam. For this study we have modified a single-disk particle simulation code, DESTIN (2), to follow two species of particles, the number of which varies in a prescribed fashion dependent upon reactor temperature as the beam converges toward the pellet.

  10. Dependence with air density of the response of the PTW SourceCheck ionization chamber for low energy brachytherapy sources

    SciTech Connect

    Tornero-López, Ana M.; Guirado, Damián; Ruiz-Arrebola, Samuel; Perez-Calatayud, Jose; Simancas, Fernando; Lallena, Antonio M.; Gazdic-Santic, Maja

    2013-12-15

    changes in the weather conditions may produce significant density corrections, and that effect should be taken into account. This effect is chamber-dependent, indicating that a specific calibration is necessary for each particular chamber. To our knowledge, this correction has not been considered so far for SourceCheck ionization chambers, but its magnitude cannot be neglected in clinical practice. The atmospheric pressure and temperature at which the chamber was calibrated need to be taken into account, and they should be reported in the calibration certificate. In addition, each institution should analyze the particular response of its SourceCheck ionization chamber and compute the adequate correction factors. In the absence of a suitable pressure chamber, a possibility for this assessment is to take measurements at different altitudes, spanning a wide enough air density range.

  11. SU-E-T-382: Influence of Compton Currents On Profile Measurements in Small- Volume Ion Chambers

    SciTech Connect

    Tanny, S; Parsai, E; Holmes, S

    2014-06-01

    Purpose: Ionization chambers in electron radiation fields are known to exhibit polarity effects due to Compton currents. Previously we have presented a unique manifestation of this effect observed with a microionization chamber. We have expanded that investigation to include three micro-ionization chambers commonly used in radiation therapy. The purpose of this project is to determine what factors influence this polarity effect for micro-chambers and how it might be mitigated. Methods: Three chambers were utilized: a PTW 31016, an Exradin A-16, and an Exradin A- 26. Beam profile scans were obtained on a Varian TrueBeam linear accelerator in combination with a Wellhofer water phantom for 6, 9, and 12 MeV electrons. Profiles were obtained parallel and perpendicular to the chamber's long axis, with both positive and negative collecting bias. Profiles were obtained with various chamber components shielded by 5 mm of Pb at 6 MeV to determine their relative contributions to this polarity effect. Results: The polarity effect was observed for all three chambers, and the ratio of the polarity effect for the Exradin chambers is proportional to the ratio of chamber volumes. Shielding the stem of both Exradin chambers diminished, but did not remove the polarity effect. However, they demonstrated no out-of-field effect when the cable was shielded with Pb. The PTW chamber demonstrated a significantly reduced polarity effect without any shielding despite its comparable volume with the A-26. Conclusions: The sensitive volume of these micro-chambers is relatively insensitive to collecting polarity. However, charge deposition within the cable can dramatically alter measured ionization profiles. This is demonstrated by the removal of the out-of-field ionization when the cable is shielded for the Exradin chambers. We strongly recommend analyzing any polarity dependence for small-volume chambers used in characterization of electron fields.

  12. Fusion studies with low-intensity radioactive ion beams using an active-target time projection chamber

    NASA Astrophysics Data System (ADS)

    Kolata, J. J.; Howard, A. M.; Mittig, W.; Ahn, T.; Bazin, D.; Becchetti, F. D.; Beceiro-Novo, S.; Chajecki, Z.; Febbrarro, M.; Fritsch, A.; Lynch, W. G.; Roberts, A.; Shore, A.; Torres-Isea, R. O.

    2016-09-01

    The total fusion excitation function for 10Be+40Ar has been measured over the center-of-momentum (c.m.) energy range from 12 to 24 MeV using a time-projection chamber (TPC). The main purpose of this experiment, which was carried out in a single run of duration 90 h using a ≈100 particle per second (pps) 10Be beam, was to demonstrate the capability of an active-target TPC to determine fusion excitation functions for extremely weak radioactive ion beams. Cross sections as low as 12 mb were measured with acceptable (50%) statistical accuracy. It also proved to be possible to separate events in which charged particles were emitted from the fusion residue from those in which only neutrons were evaporated. The method permits simultaneous measurement of incomplete fusion, break-up, scattering, and transfer reactions, and therefore fully exploits the opportunities presented by the very exotic beams that will be available from the new generation of radioactive beam facilities.

  13. Flow chamber

    SciTech Connect

    Morozov, Victor

    2011-01-18

    A flow chamber having a vacuum chamber and a specimen chamber. The specimen chamber may have an opening through which a fluid may be introduced and an opening through which the fluid may exit. The vacuum chamber may have an opening through which contents of the vacuum chamber may be evacuated. A portion of the flow chamber may be flexible, and a vacuum may be used to hold the components of the flow chamber together.

  14. THE PHYSIOLOGICAL RESPONSE OF PROSTATIC AND VESICULAR TRANSPLANTS IN THE ANTERIOR CHAMBER OF THE EYE

    PubMed Central

    Moore, Robert A.; Melchionna, Robert H.; Tolins, S. H.; Rosenblum, H. B.

    1937-01-01

    1. With a photographic method for the determination of the size of prostatic and vesicular transplants in the anterior chamber of the eye, it has been possible to follow continuously the response to an injection of a hormone. 2. The results may be briefly summarized as follows: (a) One injection of the gonadotropic substance of pregnancy urine produces a moderate increase in size; (b) subsequent injections of this same substance for a period of at least 3 months are without effect; (c) an alkaline extract of the whole anterior pituitary gland produces a similar increase; (d) all pituitary derivatives are ineffective in the castrated animal; (e) castration brings about a decrease in size that gradually loses velocity; (f) the male sex hormone produces a slight increase in intact, and a variable, at times conspicuous, increase in castrated animals; (g) the female sex hormone provokes a conspicuous increase in both intact and castrated animals; (h) the hormone of the corpus luteum has no effect; and (i) there is no evidence of synergism of the pituitary and male sex hormones nor of antagonism of the male and female sex hormones in adult rabbits. PMID:19870661

  15. Note: Fabrication of a fast-response and user-friendly environmental chamber for atomic force microscopes

    NASA Astrophysics Data System (ADS)

    Ji, Yanfeng; Hui, Fei; Shi, Yuanyuan; Han, Tingting; Song, Xiaoxue; Pan, Chengbin; Lanza, Mario

    2015-10-01

    The atomic force microscope is one of the most widespread tools in science, but many suppliers do not provide a competitive solution to make experiments in controlled atmospheres. Here, we provide a solution to this problem by fabricating a fast-response and user-friendly environmental chamber. We corroborate the correct functioning of the chamber by studying the formation of local anodic oxidation on a silicon sample (biased under opposite polarities), an effect that can be suppressed by measuring in a dry nitrogen atmosphere. The usefulness of this chamber goes beyond the example here presented, and it could be used in many other fields of science, including physics, mechanics, microelectronics, nanotechnology, medicine, and biology.

  16. Note: Fabrication of a fast-response and user-friendly environmental chamber for atomic force microscopes

    SciTech Connect

    Ji, Yanfeng; Hui, Fei; Shi, Yuanyuan; Han, Tingting; Song, Xiaoxue; Pan, Chengbin; Lanza, Mario

    2015-10-15

    The atomic force microscope is one of the most widespread tools in science, but many suppliers do not provide a competitive solution to make experiments in controlled atmospheres. Here, we provide a solution to this problem by fabricating a fast-response and user-friendly environmental chamber. We corroborate the correct functioning of the chamber by studying the formation of local anodic oxidation on a silicon sample (biased under opposite polarities), an effect that can be suppressed by measuring in a dry nitrogen atmosphere. The usefulness of this chamber goes beyond the example here presented, and it could be used in many other fields of science, including physics, mechanics, microelectronics, nanotechnology, medicine, and biology.

  17. Note: Fabrication of a fast-response and user-friendly environmental chamber for atomic force microscopes.

    PubMed

    Ji, Yanfeng; Hui, Fei; Shi, Yuanyuan; Han, Tingting; Song, Xiaoxue; Pan, Chengbin; Lanza, Mario

    2015-10-01

    The atomic force microscope is one of the most widespread tools in science, but many suppliers do not provide a competitive solution to make experiments in controlled atmospheres. Here, we provide a solution to this problem by fabricating a fast-response and user-friendly environmental chamber. We corroborate the correct functioning of the chamber by studying the formation of local anodic oxidation on a silicon sample (biased under opposite polarities), an effect that can be suppressed by measuring in a dry nitrogen atmosphere. The usefulness of this chamber goes beyond the example here presented, and it could be used in many other fields of science, including physics, mechanics, microelectronics, nanotechnology, medicine, and biology.

  18. Evaluation of the accuracy of 3DVH software estimates of dose to virtual ion chamber and film in composite IMRT QA

    SciTech Connect

    Olch, Arthur J.

    2012-01-15

    Purpose: A novel patient-specific intensity modulated radiation therapy (IMRT) QA system, 3DVH software and mapcheck 2, purports to be able to use diode array-measured beam doses and the patient's DICOM RT plan, structure set, and dose files to predict the delivered 3D dose distribution in the patient for comparison to the treatment planning system (TPS) calculated doses. In this study, the composite dose to an ion chamber and film in phantom predicted by the 3DVH and mapcheck 2 system is compared to the actual measured chamber and film doses. If validated in this context, then 3DVH can be used to perform an equivalent dose analysis as that obtained with film dosimetry and ion chamber-based composite IMRT QA. This is important for those losing their ability to perform film dosimetry for true composite IMRT QA and provides a measure of confidence in the accuracy of 3DVH 3D dose calculations which may replace phantom-based IMRT QA. Methods: The dosimetric results from 15 consecutive patient-specific IMRT QA tests performed by composite field irradiation of ion chamber and EDR2 film in a solid water phantom were compared to the predicted doses for those virtual detectors based on the calculated 3D dose by the 3DVH software using mapcheck 2 measured doses of each beam within each plan. For each of the 15 cases, immediately after performing the ion chamber plus film measurements, the mapcheck 2 was used to measure the dose for each beam of the plan. The dose to the volume of the virtual ion chamber and the dose distribution in the plane of the virtual film calculated by the 3DVH software was extracted. The ratio of the measured to 3DVH or eclipse-predicted ion chamber doses was calculated. The same plane in the phantom measured using film and calculated with eclipse was exported from 3DVH and the 2D gamma metric was used to compare the relationship between the film doses and the eclipse or 3DVH predicted planar doses. Also, the 3D gamma value was calculated in the 3DVH

  19. A new pressure chamber to study the biosynthetic response of articular cartilage to mechanical loading.

    PubMed

    Steinmeyer, J; Torzilli, P A; Burton-Wurster, N; Lust, G

    1993-01-01

    A prototype chamber was used to apply a precise cyclic or static load on articular cartilage explants under sterile conditions. A variable pressure, pneumatic controller was constructed to power the chamber's air cylinder, capable of applying, with a porous load platen, loads of up to 10 MPa at cycles ranging from 0 to 10 Hz. Pig articular cartilage explants were maintained successfully in this chamber for 2 days under cyclic mechanical loading of 0.5 Hz, 0.5 MPa. Explants remained sterile, viable and metabolically active. Cartilage responded to this load with a decreased synthesis of fibronectin and a small but statistically significant elevation in proteoglycan content. Similar but less extensive effects on fibronectin synthesis were observed with the small static load (0.016 MPa) inherent in the design of the chamber.

  20. Dermal exudate macrophages. Induction in dermal chambers and response to lymphokines.

    PubMed Central

    Goihman-Yahr, M; Ulrich, M; Noya-León, A; Rojas, A; Convit, J

    1975-01-01

    Chambers were implanted in the dorsum of guinea-pigs at the dermal-subcutaneous junction. Exudates were induced and harvested. Macrophages obtained were able to migrate in vitro. If procured from sensitized donors, macrophage migration was inhibited by the corresponding antigen. Dermal exudate macrophages are therefore subject to the effect of lymphokines. The chamber model may be useful for in vivo studies of cell to cell and cell-parasite interactions. PMID:1212821

  1. A study of airborne radon levels in Paarl houses (South Africa) and associated source terms, using electret ion chambers and gamma-ray spectrometry.

    PubMed

    Lindsay, R; Newman, R T; Speelman, W J

    2008-11-01

    Indoor radon ((222)Rn) concentrations were measured in Paarl homes by means of electret ion chambers. The concentrations varied between 28 and 465 Bq m(-3). The average values (Bq m(-3)) found in houses on the west and east side of the Berg River, which bisects Paarl, were 132 (+/-11) and 37 (+/-3), respectively. Radiometric analyses of soils show that the mean (226)Ra activity concentration is three times higher on the west than on the east side of the Berg River.

  2. TH-E-BRE-03: A Novel Method to Account for Ion Chamber Volume Averaging Effect in a Commercial Treatment Planning System Through Convolution

    SciTech Connect

    Barraclough, B; Li, J; Liu, C; Yan, G

    2014-06-15

    Purpose: Fourier-based deconvolution approaches used to eliminate ion chamber volume averaging effect (VAE) suffer from measurement noise. This work aims to investigate a novel method to account for ion chamber VAE through convolution in a commercial treatment planning system (TPS). Methods: Beam profiles of various field sizes and depths of an Elekta Synergy were collected with a finite size ion chamber (CC13) to derive a clinically acceptable beam model for a commercial TPS (Pinnacle{sup 3}), following the vendor-recommended modeling process. The TPS-calculated profiles were then externally convolved with a Gaussian function representing the chamber (σ = chamber radius). The agreement between the convolved profiles and measured profiles was evaluated with a one dimensional Gamma analysis (1%/1mm) as an objective function for optimization. TPS beam model parameters for focal and extra-focal sources were optimized and loaded back into the TPS for new calculation. This process was repeated until the objective function converged using a Simplex optimization method. Planar dose of 30 IMRT beams were calculated with both the clinical and the re-optimized beam models and compared with MapCHEC™ measurements to evaluate the new beam model. Results: After re-optimization, the two orthogonal source sizes for the focal source reduced from 0.20/0.16 cm to 0.01/0.01 cm, which were the minimal allowed values in Pinnacle. No significant change in the parameters for the extra-focal source was observed. With the re-optimized beam model, average Gamma passing rate for the 30 IMRT beams increased from 92.1% to 99.5% with a 3%/3mm criterion and from 82.6% to 97.2% with a 2%/2mm criterion. Conclusion: We proposed a novel method to account for ion chamber VAE in a commercial TPS through convolution. The reoptimized beam model, with VAE accounted for through a reliable and easy-to-implement convolution and optimization approach, outperforms the original beam model in standard IMRT QA

  3. SU-E-T-758: To Determine the Source Dwell Positions of HDR Brachytherapy Using 2D 729 Ion Chamber Array

    SciTech Connect

    Kumar, Syam; Sitha

    2015-06-15

    Purpose: Determination of source dwell positions of HDR brachytherapy using 2D 729 ion chamber array Methods: Nucletron microselectron HDR and PTW 2D array were used for the study. Different dwell positions were assigned in the HDR machine. Rigid interstitial needles and vaginal applicator were positioned on the 2D array. The 2D array was exposed for this programmed dwell positions. The positional accuracy of the source was analyzed after the irradiation of the 2D array. This was repeated for different dwell positions. Different test plans were transferred from the Oncentra planning system and irradiated with the same applicator position on the 2D array. The results were analyzed using the in house developed excel program. Results: Assigned dwell positions versus corresponding detector response were analyzed. The results show very good agreement with the film measurements. No significant variation found between the planned and measured dwell positions. Average dose response with 2D array between the planned and nearby dwell positions was found to be 0.0804 Gy for vaginal cylinder applicator and 0.1234 Gy for interstitial rigid needles. Standard deviation between the doses for all the measured dwell positions for interstitial rigid needle for 1 cm spaced positions were found to be 0.33 and 0.37 for 2cm spaced dwell positions. For intracavitory vaginal applicator this was found to be 0.21 for 1 cm spaced dwell positions and 0.06 for 2cm spaced dwell positions. Intracavitory test plans reproduced on the 2D array with the same applicator positions shows the ideal dose distribution with the TPS planned. Conclusion: 2D array is a good tool for determining the dwell position of HDR brachytherapy. With the in-house developed program in excel it is easy and accurate. The traditional way with film analysis can be replaced by this method, as the films will be more costly.

  4. Robotic radiosurgery system patient-specific QA for extracranial treatments using the planar ion chamber array and the cylindrical diode array.

    PubMed

    Lin, Mu-Han; Veltchev, Iavor; Koren, Sion; Ma, Charlie; Li, Jinsgeng

    2015-07-08

    Robotic radiosurgery system has been increasingly employed for extracranial treatments. This work is aimed to study the feasibility of a cylindrical diode array and a planar ion chamber array for patient-specific QA with this robotic radiosurgery system and compare their performance. Fiducial markers were implanted in both systems to enable image-based setup. An in-house program was developed to postprocess the movie file of the measurements and apply the beam-by-beam angular corrections for both systems. The impact of noncoplanar delivery was then assessed by evaluating the angles created by the incident beams with respect to the two detector arrangements and cross-comparing the planned dose distribution to the measured ones with/without the angular corrections. The sensitivity of detecting the translational (1-3 mm) and the rotational (1°-3°) delivery errors were also evaluated for both systems. Six extracranial patient plans (PTV 7-137 cm³) were measured with these two systems and compared with the calculated doses. The plan dose distributions were calculated with ray-tracing and the Monte Carlo (MC) method, respectively. With 0.8 by 0.8 mm² diodes, the output factors measured with the cylindrical diode array agree better with the commissioning data. The maximum angular correction for a given beam is 8.2% for the planar ion chamber array and 2.4% for the cylindrical diode array. The two systems demonstrate a comparable sensitivity of detecting the translational targeting errors, while the cylindrical diode array is more sensitive to the rotational targeting error. The MC method is necessary for dose calculations in the cylindrical diode array phantom because the ray-tracing algorithm fails to handle the high-Z diodes and the acrylic phantom. For all the patient plans, the cylindrical diode array/ planar ion chamber array demonstrate 100% / > 92% (3%/3 mm) and > 96% / ~ 80% (2%/2 mm) passing rates. The feasibility of using both systems for robotic

  5. Robotic radiosurgery system patient-specific QA for extracranial treatments using the planar ion chamber array and the cylindrical diode array.

    PubMed

    Lin, Mu-Han; Veltchev, Iavor; Koren, Sion; Ma, Charlie; Li, Jinsgeng

    2015-07-01

    Robotic radiosurgery system has been increasingly employed for extracranial treatments. This work is aimed to study the feasibility of a cylindrical diode array and a planar ion chamber array for patient-specific QA with this robotic radiosurgery system and compare their performance. Fiducial markers were implanted in both systems to enable image-based setup. An in-house program was developed to postprocess the movie file of the measurements and apply the beam-by-beam angular corrections for both systems. The impact of noncoplanar delivery was then assessed by evaluating the angles created by the incident beams with respect to the two detector arrangements and cross-comparing the planned dose distribution to the measured ones with/without the angular corrections. The sensitivity of detecting the translational (1-3 mm) and the rotational (1°-3°) delivery errors were also evaluated for both systems. Six extracranial patient plans (PTV 7-137 cm(3)) were measured with these two systems and compared with the calculated doses. The plan dose distributions were calculated with ray-tracing and the Monte Carlo (MC) method, respectively. With 0.8 by 0.8 mm(2) diodes, the output factors measured with the cylindrical diode array agree better with the commissioning data. The maximum angular correction for a given beam is 8.2% for the planar ion chamber array and 2.4% for the cylindrical diode array. The two systems demonstrate a comparable sensitivity of detecting the translational targeting errors, while the cylindrical diode array is more sensitive to the rotational targeting error. The MC method is necessary for dose calculations in the cylindrical diode array phantom because the ray-tracing algorithm fails to handle the high-Z diodes and the acrylic phantom. For all the patient plans, the cylindrical diode array/ planar ion chamber array demonstrate 100%/>;92%(3%/3 mm) passing rates. The feasibility of using both systems for robotic radiosurgery system patient-specific QA

  6. SU-E-T-242: Monte Carlo Simulations Used to Test the Perturbation of a Reference Ion Chamber Prototype Used for Small Fields

    SciTech Connect

    Vazquez Quino, L; Calvo, O; Huerta, C; DeWeese, M

    2014-06-01

    Purpose: To study the perturbation due to the use of a novel Reference Ion Chamber designed to measure small field dosimetry (KermaX Plus C by IBA). Methods: Using the Phase-space files for TrueBeam photon beams available by Varian in IAEA-compliant format for 6 and 15 MV. Monte Carlo simulations were performed using BEAMnrc and DOSXYZnrc to investigate the perturbation introduced by a reference chamber into the PDDs and profiles measured in water tank. Field sizes ranging from 1×1, 2×2,3×3, 5×5 cm2 were simulated for both energies with and without a 0.5 mm foil of Aluminum which is equivalent to the attenuation equivalent of the reference chamber specifications in a water phantom of 30×30×30 cm3 and a pixel resolution of 2 mm. The PDDs, profiles, and gamma analysis of the simulations were performed as well as a energy spectrum analysis of the phase-space files generated during the simulation. Results: Examination of the energy spectrum analysis performed shown a very small increment of the energy spectrum at the build-up region but no difference is appreciated after dmax. The PDD, profiles and gamma analysis had shown a very good agreement among the simulations with and without the Al foil, with a gamma analysis with a criterion of 2% and 2mm resulting in 99.9% of the points passing this criterion. Conclusion: This work indicates the potential benefits of using the KermaX Plus C as reference chamber in the measurement of PDD and Profiles for small fields since the perturbation due to in the presence of the chamber the perturbation is minimal and the chamber can be considered transparent to the photon beam.

  7. Bakeout Chamber Within Vacuum Chamber

    NASA Technical Reports Server (NTRS)

    Taylor, Daniel M.; Soules, David M.; Barengoltz, Jack B.

    1995-01-01

    Vacuum-bakeout apparatus for decontaminating and measuring outgassing from pieces of equipment constructed by mounting bakeout chamber within conventional vacuum chamber. Upgrade cost effective: fabrication and installation of bakeout chamber simple, installation performed quickly and without major changes in older vacuum chamber, and provides quantitative data on outgassing from pieces of equipment placed in bakeout chamber.

  8. A Specular Chamber for Off-Axis Response Evaluations of High-Rejection Optical Baffling System

    DTIC Science & Technology

    1976-06-01

    of the solar corona independently of a solar eclipse. However, the presence of dust or haze particles in the atmosphere scatters solar light coming...EVALUATION OF THE SPECULAR CHAMBER i CONCEPT ... *.******e...*....... ..... *.. 35 7 f Atmospberic Scattering Backgroundo ... ................ .... ... . 35...limitatlo-’ nicasuren’erts........ 6 Experimental Determination of the f ~cg’.kPrVwer Level Product-( bv Surfaev Scattering.......... .................. S

  9. Response of the first wetted wall of an IFE reactor chamber to the energy release from a direct-drive DT capsule

    NASA Astrophysics Data System (ADS)

    Medin, Stanislav A.; Basko, Mikhail M.; Orlov, Yurii N.; Suslin, Victor M.

    2012-07-01

    Radiation hydrodynamics 1D simulations were performed with two concurrent codes, DEIRA and RAMPHY. The DEIRA code was used for DT capsule implosion and burn, and the RAMPHY code was used for computation of X-ray and fast ions deposition in the first wall liquid film of the reactor chamber. The simulations were run for 740 MJ direct drive DT capsule and Pb thin liquid wall reactor chamber of 10 m diameter. Temporal profiles for DT capsule leaking power of X-rays, neutrons and fast 4He ions were obtained and spatial profiles of the liquid film flow parameter were computed and analyzed.

  10. Output current variation and polarity effect by electric field and ion-pair non-uniformity inside thimble-type ionization chamber

    NASA Astrophysics Data System (ADS)

    Kim, Jaecheon; Kim, Yong Kyun; Kim, Soon Young; Kim, Jong Kyung

    2007-09-01

    A new analytic approach considering both electric field and ion-pair non-uniformity has been proposed to accurately analyze the design characteristics of an ionization chamber and to interpret measurements. It is commonly assumed that ion-pairs are generated uniformly in the air volume, but such an assumption ignores various source and geometry conditions. The new approach was applied to angular dependence analysis and to polarity effect assessment in an ionization chamber. For the angular dependence analysis, whole, uniform, and non-uniform output currents were calculated as a function of the irradiation angle for an 241Am gamma-ray source. The non-uniform output current proposed in this paper was found to be closer to the measured one. This is because the non-uniform output current takes into account the ion-pair distribution in the air volume as well as the active volume determined by the electric field. For the polarity effect assessment, the amount of field distortion due to potential difference and actual current difference was calculated. Previous methods cannot appropriately estimate the variation of polarity effect because they ignore the influence of the ion-pair distribution. The polarity effect assessment using the non-uniform output current can be more useful for obtaining the practical current difference, because this assessment considers both the variation of active volume and the ion-pair non-uniformity according to source conditions such as the irradiation angle and the distance. It is important to precisely calculate not only the active volume, but also the variation in the ion-pair distribution.

  11. Thermal conditions in freezing chambers and prediction of the thermophysiological responses of workers

    NASA Astrophysics Data System (ADS)

    Raimundo, A. M.; Oliveira, A. V. M.; Gaspar, A. R.; Quintela, D. A.

    2015-11-01

    The present work is dedicated to the assessment of the cold thermal strain of human beings working within freezing chambers. To obtain the present results, both field measurements and a numerical procedure based on a modified version of the Stolwijk thermoregulation model were used. Eighteen freezing chambers were considered. A wide range of physical parameters of the cold stores, the workers clothing insulation, and the working and recovering periods were observed. The combination of these environmental and individual parameters lead to different levels of thermal stress, which were grouped under three categories. Some good practices were observed in the field evaluations, namely situations with appropriate level of clothing protection and limited duration of exposure to cold avoiding unacceptable level of hypothermia. However, the clothing ensembles normally used by the workers do not provide the minimum required insulation, which suggests the possibility of the whole body cooling for levels higher than admissible. The numerical predictions corroborate the main conclusions of the field survey. The results obtained with both methodologies clearly show that, for the low temperature of the freezing chambers, the clothing insulation is insufficient, the exposure periods are too long, and the recovering periods are inadequate. Thus, high levels of physiological strain can indeed be reached by human beings under such working environments.

  12. SU-E-T-137: Attenuation of Carbon Fiber IGRT Couch Top for SBRT By Using a MapCheck 2 and Ion Chamber

    SciTech Connect

    Dou, K; Li, B; Lerma, F; Sarfaraz, M; Jacobs, M; Laser, B

    2015-06-15

    Purpose: It is common to use posterior oblique beams in intensity-modulated radiation therapy (IMRT) and volumetric-modulated arc therapy (VMAT) for regular and stereotactic body radiotherapy (SBRT). Beam attenuation by the treatment couch is not negligible when the couch is in the beam portal. In this study, we have correlated relative dose versus beam angle through a MapCheck 2TM diode array and an ionization chamber measurement. Methods: A Varian TrueBeam linear accelerator equipped with the image-guided radiation therapy (IGRT) carbon fiber couch was used for delivery of radiation with different photon energies of 6MV, 15MV and 6MV FFF. A MapCHECK 2TM diode array with a MapPhan was employed for the measurement at three field sizes (3 by 3, 5 by 5, and 10 by 10 cm). The independent measurement was performed with an ionization chamber placed at the center of an acrylic cylindrical phantom at the isocenter. The measured data with the MapCHECK 2TM diode array were averaged over the central 2×2 cm diodes for each measurement. The couch attenuation was deduced from the angular dependence with and without the couch involvement. Results: For the MapCHECK 2TM with MapPhan used only the obvious attenuation was observed at the beam angle between 5 and 10 degree from the angular dependence using a 6MV photon beam. The similar Result was obtained for the MapCHECK 2TM /MapPhan with the couch involvement. The couch attenuation was then deduced from the difference of these two sets of data measurements. Maximum couch attenuation was found up to 4.2% which was verified with the ion chamber measurement. Conclusion: A maximum attenuation of 4.2% was found for the carbon fiber couch top using the MapCHECK 2TM/MapPhan, which is consistent with the ion chamber measurement.

  13. SU-E-T-82: A Study On Enhanced Dynamic Wedge (EDW) Dosimetry Using 2D Seven29 Ion Chamber Array Detector

    SciTech Connect

    Kumar, Syam; Aparna

    2015-06-15

    Purpose: To study the dosimetric properties of Enhanced Dynamic Wedge (EDW) using PTW Seven29 ion chamber array Methods: PTW Seven29 ion chamber array and Solid Water phantoms for different depths were used for the study. The study was carried out in Varian Clinac ix with photon energies, 6MV & 15MV. Primarily the solid water phantoms with the 2D array were scanned using a CT scanner (GE Optima 580) at different depths. These scanned images were used for EDW planning in an Eclipse treatment planning system (version 10). Planning was done for different wedge angles and for different depths for 6MV & 15MV. A dose of 100 CGy was delivered in each cases. For each delivery, calculated the Monitoring Unit (MU) required. Same set-up was created before delivering the plans in Varian Clinac-ix. For each clinically relevant depth and for different wedge angles, the same MU was delivered as calculated. Different wedged dose distributions where reconstructed from the measured 2D array data using the in-house developed excel program. Results: It is observed that the shoulder like region in the profile which reduces as depth increases. For the same depth and energy, the percentage difference between planned and measured dose is lesser than 3%. For smaller wedge angles, the percentage difference is found to be greater than 3% for the largest wedge angle. Standard deviation between measured doses at shoulder region for planned and measured profiles is 0.08 and 0.02 respectively. Standard deviations between planned and measured wedge factors for different depths (2.5cm, 5cm, 10cm, and 15cm) are (0.0021, 0.0007, 0.0050, 0.0001) for 6MV and (0.0024, 0.0191, 0.0013, 0.0005) for 15MV respectively. Conclusion: The 2D Seven29 ion chamber array is a good tool for the Enhanced Dynamic Wedge (EDW) dosimetry.

  14. Verifying Sensor Response to Difficult Chemicals with a New Test Chamber Concept

    SciTech Connect

    Maughan, A. D.; Birnbaum, Jerome C.; Probasco, Kathleen M.

    2004-06-01

    In this article we discuss the application of technology innovations to optimize detection of hard-to-measure (less- or semi-volatile) compounds. These chemicals are found all around us: in pesticides and herbicides, the higher boiling polyaromatic hydrocarbons in diesel exhaust, and linked polyurethane foams in products ranging from hiking boots to acoustic ceilings. They appear in low concentrations and evaporate very slowly. These heavier chemicals are rarely measured accurately because they stick to surfaces and sampling equipment and, consequently, are not reliably sampled or delivered to analytical detectors. It’s like trying to identify cold, sticky honey by getting it to flow in through a sampling tube to a detector –it will hardly move. Honey generally coats out on surfaces and sample lines to the extent that even if it is detected, the amount present is vastly underestimated. Researchers at Pacific Northwest National Laboratory (PNNL) addressed the problem by developing a chamber facility with instrumentation that can overcome the under-reporting of these ubiquitous chemical compounds. The atmospheric chemistry chamber provides a controlled environment in which to certify the accuracy of and conditions under which sensors can best respond to volatile and semi-volatile chemicals. The facility is designed to handle and measure chemicals at the levels at which they are found in nature. Test environments can be created in which atmospheric concentrations are at low part-per-trillion concentrations. These concentrations are equivalent to an herbicide off-gassing from a commercially grown apple. The chamber can be set up to simulate releases ranging from industrial vents with high concentrations to releases from surfaces, soils, and/or vegetation where the concentrations are low.

  15. Spectral differences in 6 MV beams with matched PDDs and the effect on chamber response

    NASA Astrophysics Data System (ADS)

    Lye, J. E.; Butler, D. J.; Ramanathan, G.; Franich, R. D.

    2012-11-01

    The Australian Radiation Protection and Nuclear Safety Agency (ARPANSA) has installed an Elekta Synergy platform linac to establish a direct megavoltage primary standard calibration service, instead of relying on calibrations derived from 60Co. One of the 6 MV beams of the ARPANSA linac has been approximately matched to the Varian high energy platform 6 MV photon beam. The electron beam energy was adjusted to match the percentage depth dose (PDD) curve and TPR20,10. This work calculates the error introduced when using a calibration factor from this Elekta Synergy Platform linac on a Varian high-energy platform beam at 6 MV. Monte Carlo models of the Varian and matched Elekta accelerator accurately predict the measured PDDs and profiles, but show significantly different energy spectra, resulting mainly from differences in target thickness between the two accelerators. Monte Carlo modelling of the energy correction factor kQ of a secondary standard NE2561 chamber shows a difference of 0.4% between the Varian and the Varian-matched Elekta beams. Although small, this is a significant discrepancy for primary standard calibrations. Similar variations are expected for chambers of similar construction, and additional variations may occur with other linac manufacturers. The work has also investigated the design of a custom flattening filter to precisely match the energy spectrum of the Varian beam on the Elekta platform.

  16. Detection of Amines and Ammonia with an Ambient Pressure Mass Spectrometer using a Corona Discharge Ion Source, in an Urban Atmosphere and in a Teflon Film Chamber

    NASA Astrophysics Data System (ADS)

    Alves, M.; Hanson, D. R.; Grieves, C.; Ortega, J. V.

    2015-12-01

    Amines and ammonia are an important group of molecules that can greatly affect atmospheric particle formation that can go on to impact cloud formation and their scattering of thermal and solar radiation, and as a result human health and ecosystems. In this study, an Ambient Pressure Mass Spectrometer (AmPMS) that is selective and sensitive to molecules with a high proton affinity, such as amines, was coupled with a newly built corona discharge ion source. AmPMS was used to monitor many different nitrogenous compound that are found in an urban atmosphere (July 2015, Minneapolis), down to the single digit pmol/mol level. Simultaneous to this, a proton transfer mass spectrometer also sampled the atmosphere through an inlet within 20 m of the AmPMS inlet. In another set of studies, a similar AmPMS was attached to a large Teflon film chamber at the Atmospheric Chemistry Division at NCAR (August 2015, Boulder). Exploratory studies are planned on the sticking of amines to the chamber walls as well as oxidizing the amine and monitoring products. Depending on the success of these studies, results will be presented on the reversability of amine partitioning and mass balance for these species in the chamber.

  17. A comparison of linaclotide and lubiprostone dosing regimens on ion transport responses in human colonic mucosa

    PubMed Central

    Kang, Sang Bum; Marchelletta, Ronald R; Penrose, Harrison; Docherty, Michael J; McCole, Declan F

    2015-01-01

    Linaclotide, a synthetic guanylyl cyclase C (GC-C) agonist, and the prostone analog, Lubiprostone, are approved to manage chronic idiopathic constipation and constipation-predominant irritable bowel syndrome. Lubiprostone also protects intestinal mucosal barrier function in ischemia. GC-C signaling regulates local fluid balance and other components of intestinal mucosal homeostasis including epithelial barrier function. The aim of this study was to compare if select dosing regimens differentially affect linaclotide and lubiprostone modulation of ion transport and barrier properties of normal human colonic mucosa. Normal sigmoid colon biopsies from healthy subjects were mounted in Ussing chambers. Tissues were treated with linaclotide, lubiprostone, or vehicle to determine effects on short-circuit current (Isc). Subsequent Isc responses to the cAMP agonist, forskolin, and the calcium agonist, carbachol, were also measured to assess if either drug caused desensitization. Barrier properties were assessed by measuring transepithelial electrical resistance. Isc responses to linaclotide and lubiprostone were significantly higher than vehicle control when administered bilaterally or to the mucosal side only. Single versus cumulative concentrations of linaclotide showed differences in efficacy while cumulative but not single dosing caused desensitization to forskolin. Lubiprostone reduced forskolin responses under all conditions. Linaclotide and lubiprostone exerted a positive effect on TER that was dependent on the dosing regimen. Linaclotide and lubiprostone increase ion transport responses across normal human colon but linaclotide displays increased sensitivity to the dosing regimen used. These findings may have implications for dosing protocols of these agents in patients with constipation. PMID:26038704

  18. A comparison of linaclotide and lubiprostone dosing regimens on ion transport responses in human colonic mucosa.

    PubMed

    Kang, Sang Bum; Marchelletta, Ronald R; Penrose, Harrison; Docherty, Michael J; McCole, Declan F

    2015-03-01

    Linaclotide, a synthetic guanylyl cyclase C (GC-C) agonist, and the prostone analog, Lubiprostone, are approved to manage chronic idiopathic constipation and constipation-predominant irritable bowel syndrome. Lubiprostone also protects intestinal mucosal barrier function in ischemia. GC-C signaling regulates local fluid balance and other components of intestinal mucosal homeostasis including epithelial barrier function. The aim of this study was to compare if select dosing regimens differentially affect linaclotide and lubiprostone modulation of ion transport and barrier properties of normal human colonic mucosa. Normal sigmoid colon biopsies from healthy subjects were mounted in Ussing chambers. Tissues were treated with linaclotide, lubiprostone, or vehicle to determine effects on short-circuit current (I sc). Subsequent I sc responses to the cAMP agonist, forskolin, and the calcium agonist, carbachol, were also measured to assess if either drug caused desensitization. Barrier properties were assessed by measuring transepithelial electrical resistance. I sc responses to linaclotide and lubiprostone were significantly higher than vehicle control when administered bilaterally or to the mucosal side only. Single versus cumulative concentrations of linaclotide showed differences in efficacy while cumulative but not single dosing caused desensitization to forskolin. Lubiprostone reduced forskolin responses under all conditions. Linaclotide and lubiprostone exerted a positive effect on TER that was dependent on the dosing regimen. Linaclotide and lubiprostone increase ion transport responses across normal human colon but linaclotide displays increased sensitivity to the dosing regimen used. These findings may have implications for dosing protocols of these agents in patients with constipation.

  19. Determination of PM10 and its ion composition emitted from biomass burning in the chamber for estimation of open burning emissions.

    PubMed

    Sillapapiromsuk, Sopittaporn; Chantara, Somporn; Tengjaroenkul, Urai; Prasitwattanaseree, Sukon; Prapamontol, Tippawan

    2013-11-01

    Biomass samples including agricultural waste (rice straw and maize residue) and forest leaf litter were collected from Chiang Mai Province, Thailand for the burning experiment in the self-designed stainless steel chamber to simulate the emissions of PM10. The burning of leaf litter emitted the highest PM10 (1.52±0.65 g kg(-1)). The PM10-bound ions emitted from the burning of rice straw and maize residue showed the same trend, which was K(+)>Cl(-)>SO4(2-)>NH4(+)>NO3(-). However, the emissions from maize residue burning were ~1.5-2.0 times higher than those from the rice straw burning. The ion content emitted from leaf litter burning was almost the same for all ion species. Noticeably, K(+) and Cl(-) concentrations were ~2-4 times lower than those emitted from agricultural waste burning. It can be deduced that K(+) and Cl(-) were highly emitted from agricultural waste burning due to the use of fertilizer and herbicides in the field, respectively. Based on emission values obtained from the chamber, the pollutant emission rate from open burning was calculated. Burned areas in Chiang Mai Province were 3510 and 866 km(2) in 2010 and 2011, respectively. Forest burning was 71-88%, while agricultural land burning accounted for 12-29% (rice field: crop field=1:3) of total burned area. Therefore, emissions of PM10 from open burning in Chiang Mai were 3051 ton (2010) and 705 ton (2011). Major ions emitted from agricultural waste burning were found to be K(+) and Cl(-), while those from forest burning were SO4(2-) and K(+).

  20. Exposure chamber

    DOEpatents

    Moss, Owen R.; Briant, James K.

    1983-01-01

    An exposure chamber includes an imperforate casing having a fluid inlet at the top and an outlet at the bottom. A single vertical series of imperforate trays is provided. Each tray is spaced on all sides from the chamber walls. Baffles adjacent some of the trays restrict and direct the flow to give partial flow back and forth across the chambers and downward flow past the lowermost pan adjacent a central plane of the chamber.

  1. Indirect prediction of surface ozone concentration by plant growth responses in East Asia using mini-open top chambers.

    PubMed

    Kohno, Yoshihisa; Matsumura, Hideyuki; Miwa, Makoto; Yonekura, Tetsushi; Aihara, Keiji; Umponstira, Chanin; Le, Vo Thanh; Ngoc, Nguyen Thuy; Viet, Phanm Hung; Wei, Ma

    2013-03-01

    We developed small and mobile open top chambers (mini-OTC) measuring 0.6 m (W) × 0.6 m (D) × 1.2 m (H) with an air duct of 0.6 m (W) × 0.23 m (D) × 1.2 m (H). The air duct can be filled with activated charcoal to blow charcoal filtered air (CF) into the chamber, as opposed to non-filtered ambient air (NF). Ozone sensitive radish Raphanus sativus cv. Red Chime and rosette pakchoi Brassica campestris var. rosularis cv. ATU171 were exposed to NF and CF in mini-OTCs at different locations in East Asia. A total of 29 exposure experiments were conducted at nine locations, Shanghai, China, Ha Noi, Vietnam, Lampang, Phitsanulok and Pathumtani, Thailand, and Hiratsuka, Kisai, Abiko and Akagi, Japan. Although no significant relationships between the mean concentrations of ambient O(3) during the experimental period and the growth responses were observed for either species, multiple linear regression analysis suggested a good relationship between the biomass responses in each species and the O(3) concentration, temperature, and relative humidity. The cumulative daily mean O(3) (ppb/day) could be indirectly predicted by NF/CF based on the dry weight ratio of biomass, mean air temperature, and relative air humidity.

  2. Liquid-filled ionization chamber temperature dependence

    NASA Astrophysics Data System (ADS)

    Franco, L.; Gómez, F.; Iglesias, A.; Pardo, J.; Pazos, A.; Pena, J.; Zapata, M.

    2006-05-01

    Temperature and pressure corrections of the read-out signal of ionization chambers have a crucial importance in order to perform high-precision absolute dose measurements. In the present work the temperature and pressure dependences of a sealed liquid isooctane filled ionization chamber (previously developed by the authors) for radiotherapy applications have been studied. We have analyzed the thermal response of the liquid ionization chamber in a ˜20C interval around room temperature. The temperature dependence of the signal can be considered linear, with a slope that depends on the chamber collection electric field. For example, a relative signal slope of 0.27×10-2 K-1 for an operation electric field of 1.67×106 V m-1 has been measured in our detector. On the other hand, ambient pressure dependence has been found negligible, as expected for liquid-filled chambers. The thermal dependence of the liquid ionization chamber signal can be parametrized within the Onsager theory on initial recombination. Considering that changes with temperature of the detector response are due to variations in the free ion yield, a parametrization of this dependence has been obtained. There is a good agreement between the experimental data and the theoretical model from the Onsager framework.

  3. Target chambers for gammashpere

    SciTech Connect

    Carpenter, M.P.; Falout, J.W.; Nardi, B.G.

    1995-08-01

    One of our responsibilities for Gammasphere, was designing and constructing two target chambers and associated beamlines to be used with the spectrometer. The first chamber was used with the early implementation phase of Gammasphere, and consisted of two spun-Al hemispheres welded together giving a wall thickness of 0.063 inches and a diameter of 12 inches.

  4. Development and application of a novel environmental preference chamber for assessing responses of laboratory mice to atmospheric ammonia.

    PubMed

    Green, Angela R; Wathes, Christopher M; Demmers, Theo G M; Clark, Judy MacArthur; Xin, Hongwei

    2008-03-01

    A novel environmental preference chamber (EPC) was developed and used to assess responses of laboratory mice to atmospheric ammonia. The EPC features 1) a test chamber with 4 individually ventilated, mutually accessible compartments; b) automated tracking of mouse movements by using paired infrared sensors; c) identification of individual mice by using photosensors; d) monitoring and regulation of the NH3 concentration in each compartment; and e) personal-computer-based data acquisition. In an initial preference study with the EPC, 4 groups of 4 laboratory mice (BALB/c/Bkl; body weight, 13.4 to 18.4 g) were each given a choice among 4 NH3 concentrations (mean +/- SE) of 4 +/- 2, 30 +/- 2, 56 +/- 4, and 110 +/- 6 ppm for 2 d after a 2-d familiarization period. Once trained to use the intercompartment tunnels, the mice made extensive use of the EPC, with each group making more than 2000 intercompartment movements during 48 h. Video recording verified the results of the automatic tracking system, which detected and correctly determined mouse location for 79% of the moves. The use of photosensors proved to be ineffective in recognizing individual mice. Although the EPC would benefit from refinement and further development, it simplified analysis of locomotion behavioral data. Results of the preference study indicated that the mice exhibited no clear preference for, or aversion to, any of the experimental concentrations of ammonia and that the mice clearly preferred the upper 2 compartments of the chamber over the lower 2 compartments. Further investigation should be conducted to verify these preliminary results and explore other preferences of laboratory mice for environmental conditions and resources.

  5. Smart responsive microcapsules capable of recognizing heavy metal ions.

    PubMed

    Pi, Shuo-Wei; Ju, Xiao-Jie; Wu, Han-Guang; Xie, Rui; Chu, Liang-Yin

    2010-09-15

    Smart responsive microcapsules capable of recognizing heavy metal ions are successfully prepared with oil-in-water-in-oil double emulsions as templates for polymerization in this study. The microcapsules are featured with thin poly(N-isopropylacrylamide-co-benzo-18-crown-6-acrylamide) (P(NIPAM-co-BCAm)) membranes, and they can selectively recognize special heavy metal ions such as barium(II) or lead(II) ions very well due to the "host-guest" complexation between the BCAm receptors and barium(II) or lead(II) ions. The stable BCAm/Ba(2+) or BCAm/Pb(2+) complexes in the P(NIPAM-co-BCAm) membrane cause a positive shift of the volume phase transition temperature of the crosslinked P(NIPAM-co-BCAm) hydrogel to a higher temperature, and the repulsion among the charged BCAm/Ba(2+) or BCAm/Pb(2+) complexes and the osmotic pressure within the P(NIPAM-co-BCAm) membranes result in the swelling of microcapsules. Induced by recognizing barium(II) or lead(II) ions, the prepared microcapsules with P(NIPAM-co-BCAm) membranes exhibit isothermal and significant swelling not only in outer and inner diameters but also in the membrane thickness. The proposed microcapsules in this study are highly attractive for developing smart sensors and/or carriers for detection and/or elimination of heavy metal ions.

  6. Calcium ions facilitate body heat emission response to warming.

    PubMed

    Tkachenko, E Ya; Khramova, G M; Kozyreva, T V

    2015-01-01

    Involvement of various areas of the body surface in heat emission response to warming is characterized by a certain succession. The first response preceding the deep body temperature rise is dilation of ear skin vessels. Then, an increase in deep body temperature is counterbalanced by vascular reaction in the tail region, which plays the leading role in up-regulation of heat emission. Calcium ions accelerate the vascular response to warming in both regions, although they produce no effect on the maximum level of heat emission. Our findings confirm the involvement of Ca(2+)-dependent mechanisms in activation of the processes aimed at stabilization of body temperature in warm-blooded animals. The role of heat-sensitive TRPV1 ion channels determining modality of the temperature signal and direction of effector reactions is discussed.

  7. Role of calcium ions in phytochrome responses: an update

    NASA Technical Reports Server (NTRS)

    Roux, S. J.; Wayne, R. O.; Datta, N.

    1986-01-01

    Recent findings related to the role of calcium ions in phytochrome responses are reviewed and summarized. Hypotheses tested are the activation of calmodulin by light-regulated Ca2+ transport in cells and the photoinduction of calmodulin-activated enzyme activities. Discussion focuses on evidence that Ca2+ helps to regulate phytochrome responses, calcium requirements for photoinduced spore germination in the fern Onoclea, Ca2+ fluxes and phytochrome function in the alga Mougeotia, calmodulin antagonist blocking of red-light stimulated chloroplast rotation, the role of phosphorylation in calmodulin-regulated responses, and phytochrome regulation of nuclear protein phosphorylation.

  8. Physiological, Behavioral, and Histological Responses of Male C57BL/6N Mice to Different CO2 Chamber Replacement Rates

    PubMed Central

    Boivin, Gregory P; Bottomley, Michael A; Dudley, Emily S; Schiml, Patricia A; Wyatt, Christopher N; Grobe, Nadja

    2016-01-01

    Rodent euthanasia with CO2 by using gradual displacement of 10% to 30% of the chamber volume per minute is considered acceptable by the AVMA Panel on Euthanasia. However, whether a 50% to 100% chamber replacement rate (CRR) of CO2 is more painful or distressful than 10% to 30% CRR is unclear. Therefore, we examined physiological and behavioral parameters, corticosterone and ACTH levels, and lung histology of mice euthanized at CRR of 15%, 30%, 50%, or 100%. Adult male C57BL/6N mice were euthanized at different CO2 CRR as physiological parameters were recorded telemetrically. Video recordings were reviewed to determine when the mouse first became ataxic, when it was fully recumbent (characterized by the mouse's nose resting on the cage floor), and when breathing stopped. Overall, CO2 euthanasia increased cardiovascular parameters and activity. Specific significant differences that were associated with 50% to 100% compared with 15% to 30% CO2 CRR included an increase in systolic blood pressure per second from initiation of CO2 until ataxia, a decrease in total diastolic blood pressure until ataxia, and a decrease in total heart rate until ataxia, immobility, and death. All physiological responses occurred more rapidly with higher CRR. Activity levels, behavioral responses, plasma adrenocorticotropic hormone and corticosterone levels, and lung pathology were not different between groups. We found no physiological, behavioral, or histologic evidence that 15% or 30% CO2 CRR is less painful or distressful than is 50% or 100% CO2 CRR. We conclude that 50% to 100% CO2 CRR is acceptable for euthanizing adult male C57BL/6N mice. PMID:27423153

  9. Exposure chamber

    DOEpatents

    Moss, Owen R.

    1980-01-01

    A chamber for exposing animals, plants, or materials to air containing gases or aerosols is so constructed that catch pans for animal excrement, for example, serve to aid the uniform distribution of air throughout the chamber instead of constituting obstacles as has been the case in prior animal exposure chambers. The chamber comprises the usual imperforate top, bottom and side walls. Within the chamber, cages and their associated pans are arranged in two columns. The pans are spaced horizontally from the walls of the chamber in all directions. Corresponding pans of the two columns are also spaced horizontally from each other. Preferably the pans of one column are also spaced vertically from corresponding pans of the other column. Air is introduced into the top of the chamber and withdrawn from the bottom. The general flow of air is therefore vertical. The effect of the horizontal pans is based on the fact that a gas flowing past the edge of a flat plate that is perpendicular to the flow forms a wave on the upstream side of the plate. Air flows downwardly between the chamber walls and the outer edges of the pan. It also flows downwardly between the inner edges of the pans of the two columns. It has been found that when the air carries aerosol particles, these particles are substantially uniformly distributed throughout the chamber.

  10. A smog chamber study coupling a photoionization aerosol electron/ion spectrometer to VUV synchrotron radiation: organic and inorganic-organic mixed aerosol analysis

    NASA Astrophysics Data System (ADS)

    Baeza-Romero, María Teresa; Gaie-Levrel, Francois; Mahjoub, Ahmed; López-Arza, Vicente; Garcia, Gustavo A.; Nahon, Laurent

    2016-07-01

    A reaction chamber was coupled to a photoionization aerosol time-of-flight mass spectrometer based on an electron/ion coincidence scheme and applied for on-line analysis of organic and inorganic-organic mixed aerosols using synchrotron tunable vacuum ultraviolet (VUV) photons as the ionization source. In this proof of principle study, both aerosol and gas phase were detected simultaneously but could be differentiated. Present results and perspectives for improvement for this set-up are shown in the study of ozonolysis ([O3] = 0.13-3 ppm) of α-pinene (2-3 ppm), and the uptake of glyoxal upon ammonium sulphate. In this work the ozone concentration was monitored in real time, together with the particle size distributions and chemical composition, the latter taking advantage of the coincidence spectrometer and the tuneability of the synchrotron radiation as a soft VUV ionization source.

  11. Wire chamber

    DOEpatents

    Atac, Muzaffer

    1989-01-01

    A wire chamber or proportional counter device, such as Geiger-Mueller tube or drift chamber, improved with a gas mixture providing a stable drift velocity while eliminating wire aging caused by prior art gas mixtures. The new gas mixture is comprised of equal parts argon and ethane gas and having approximately 0.25% isopropyl alcohol vapor.

  12. Inverse combustion force estimation based on response measurements outside the combustion chamber and signal processing

    NASA Astrophysics Data System (ADS)

    Hosseini Fouladi, Mohammad; Mohd. Nor, Mohd. Jailani; Kamal Ariffin, Ahmad; Abdullah, Shahrir

    2009-11-01

    Exposure to vibration has various physiological effects on vehicle passengers. Engine is one of the main sources of vehicle vibration. The major causes of engine vibration are combustion forces transmitted through the pistons and connection rods. Evaluation of sources is the first step to attenuate this vibration. Assessment of these sources is not an easy task because internal parts of machinery are not accessible. Often, instrumentation for such systems is costly, time consuming and some modifications would be necessary. Aim of the first part of this paper was to validate an inverse technique and carry out mobility analysis on a vehicle crankshaft to achieve matrix of Frequency Response Functions (FRFs). Outcomes were implemented to reconstruct the applied force for single and multiple-input systems. In the second part, the validated inverse technique and FRFs were used to estimate piston forces of an operating engine. Bearings of crankshaft were chosen as nearest accessible parts to piston connecting rods. Accelerometers were connected to the bearings for response measurement during an ideal engine operation. These responses together with FRFs, which were estimated in the previous part, were utilised in the inverse technique. Tikhonov regularization was used to solve the ill-conditioned inverse system. Two methods, namely L-curve criterion and Generalized Cross Validation (GCV), were employed to find the regularization parameter for the Tikhonov method. The inverse problem was solved and piston forces applied to crankpins were estimated. Results were validated by pressure measurement inside a cylinder and estimating the corresponding combustion force. This validation showed that inverse technique and measurement outcomes were roughly in agreement. In presence of various noise, L-curve criterion conduces to more robust results compared to the GCV method. But in the absence of high correlation between sources ( f>600 HzHz), the GCV technique leads to more accurate

  13. Performance of Current-Mode Ion Chambers as Beam Monitors in a Pulsed Cold Neutron Beam for the NPDGamma experiment

    NASA Astrophysics Data System (ADS)

    Gillis, R. Chad

    2006-10-01

    The NPDGamma collaboration has built and commissioned an apparatus to measure the parity-violating gamma asymmetry A in the low energy np capture process n+p->d+ γ. The asymmetry in question is a 10-8 correlation between the spin of the incident (polarized) neutron and the outgoing 2.2 MeV gamma ray. A set of purpose-built, 3He-filled ionization chambers read out in current mode is used to monitor the incident neutron flux, the beam polarization, and the transmission of the liquid para-hydrogen target during the NPDGamma measurements. As will be described in the talk, these beam monitors are simple, reliable, low-noise detectors that have performed excellently for NPDGamma. We have verified that the beam monitor signals can be interpreted to reproduce the known time-of-flight dependence of beam flux from the LANSCE pulsed cold neutron source, and that the neutron beam polarization can be measured at the 2% level from direct measurements of the transmission of the beam through the beam polarizer.

  14. IFE Chamber Technology - Status and Future Challenges

    SciTech Connect

    Meier, W.R.; Raffray, A.R.; Abdel-Khalik, S.I.; Kulcinski, G.L.; Latowski, J.F.; Najmabadi, F.; Olson, C.L.; Peterson, P.F.; Ying, A.; Yoda, M.

    2003-07-15

    Significant progress has been made on addressing critical issues for inertial fusion energy (IFE) chambers for heavy-ion, laser and Z-pinch drivers. A variety of chamber concepts are being investigated including drywall (currently favored for laser IFE), wetted-wall (applicable to both laser and ion drivers), and thick-liquid-wall (favored by heavy ion and z-pinch drivers). Recent progress and remaining challenges in developing IFE chambers are reviewed.

  15. IFE Chamber Technology - Status and Future Challenges

    SciTech Connect

    Meier, W R; Raffrary, A R; Abdel-Khalik, S; Kulcinski, G; Latkowski, J F; Najmabadi, F; Olson, C L; Peterson, P F; Ying, A; Yoda, M

    2002-11-15

    Significant progress has been made on addressing critical issues for inertial fusion energy (IFE) chambers for heavy-ion, laser and Z-pinch drivers. A variety of chamber concepts are being investigated including dry-wall (currently favored for laser IFE), wetted-wall (applicable to both laser and ion drivers), and thick-liquid-wall favored by heavy ion and z-pinch drivers. Recent progress and remaining challenges in developing IFE chambers are reviewed.

  16. SU-E-T-172: Characterization of TLD-100 (LiF:Mg,Ti) Microcube Energy Response in a Cylindrical Chamber Phantom

    SciTech Connect

    Desai, V; Hammer, C; Kunugi, K; Culberson, W; DeWerd, L

    2015-06-15

    Purpose: To characterize the energy response of TLD-100 microcubes inside a Virtual Water chamber phantom. Methods: Four TLD microcubes were placed inside a water-proof Virtual Water (VW) chamber phantom and irradiated to a known dose on a Varian linac in a 1D water tank. These chamber phantoms were then replaced by TLD-100 chips inside a separate VW paddle and irradiated to the same dose. Each energy response reading was calculated as light output per unit dose in nC/cGy and normalized to a calibration set irradiated to the same dose in 60Co. The differences in response between the TLD chips and microcubes were then analyzed. Results: Across all energies, the average microcube response was less sensitive to energy than the average chip response with both falling consistently within 2.8% of previously established values in the literature Conclusion: TLD microcubes showed a lower average sensitivity to energy than their TLD chip counterparts. The use of TLD-100 microcubes inside the chamber phantom was validated against TLD-100 chips inside of VW paddles.

  17. Study of timing response and charge spectra of glass based Resistive Plate Chamber detectors for INO-ICAL experiment

    NASA Astrophysics Data System (ADS)

    Gaur, A.; Kumar, A.; Naimuddin, Md.

    2017-03-01

    Resistive Plate chambers (RPCs) are robust and affordable gaseous detectors that combine low cost with excellent timing, good spatial resolution and fast response to the incoming particles. The India Based Neutrino Observatory is an approved project aimed at building a magnetised Iron Calorimeter (ICAL) detector to study Neutrino physics and related issues. The ICAL experiment will utilize about 29000 RPC's as active detector elements, sandwiched between alternate plates of thick iron. The RPC detectors will be used to detect muons produced from the atmospheric neutrinos interaction with an iron target. The spatial information of the muons will be extracted from the two dimensional readout and the hit position in the respective layers. The up going and down going directionality will be obtained using the time stamp of hits in the active detectors. The charge induced by the particle and its behaviour with respect to the applied voltage play a significant role in designing the readout electronics for the detector. In this paper, we present the timing and charge measurement of single gap glass based RPC detectors. We will also report about studies on the dependence of the timing and charge response of these RPC detectors as a function of the gas composition.

  18. [Dual chamber rate responsive pacing and chronotropic insufficiency. Comparison of double and respiratory sensors].

    PubMed

    Lascault, G; Pansard, Y; Scholl, J M; Abraham, P; Dupuis, J M; Victor, J; Copie, X; Alonso, C; Sarrazin, E

    2001-03-01

    Late responsive DDD pacemakers are the most technically advanced devices presently available. These pacemakers are particularly useful in patients with chronotropic insufficiency when the sinus node is incapable of accelerating during exercise. The latest pacemakers have two sensors to reproduce optimal physiological sinus acceleration. The aim of this study was to analyse the performances of a new rate responsive pacemaker with a double activity and respiratory sensor, the interaction of which is automatically controlled by a sophisticated algorithm, in 12 patients (8 men and 4 women) with a mean age of 75 +/- 7 years. Analysis was based on the performance of the sensors used singly or in association: during three exercise stress tests with measurement of the VO2 max; during everyday activities using the data archived by the pacemaker and the answers to a simplified questionnaire on quality of life. The results showed that during exercise stress testing with measurement of VO2 max, the best performances were obtained with the double sensor or the respiratory sensor compared with the activity sensor alone, suggesting that these two sensors are more effective in intense exercise. This tendency was also observed in the analysis of the memory bank of the pacemaker which showed that the total duration of the faster heart rates was greater with the two sensors. On the other hand, the quality of life was not significantly different, whichever sensor was studied. Longer scale trials are necessary to appreciate the real value of these new double sensor pacing devices and to identify the best indications for their usage.

  19. IONIZATION CHAMBER

    DOEpatents

    Redman, W.C.; Shonka, F.R.

    1958-02-18

    This patent describes a novel ionization chamber which is well suited to measuring the radioactivity of the various portions of a wire as the wire is moved at a uniform speed, in order to produce the neutron flux traverse pattern of a reactor in which the wire was previously exposed to neutron radiation. The ionization chamber of the present invention is characterized by the construction wherein the wire is passed through a tubular, straight electrode and radiation shielding material is disposed along the wire except at an intermediate, narrow area where the second electrode of the chamber is located.

  20. A novel fast neutron dosemeter based on fission chambers. Part I: Principles of operation and theoretical response in neutron therapy radiation fields.

    PubMed

    Porter, D; Lawson, R C; Hannan, W J

    1975-05-01

    A novel method is proposed of accurately measuring fast neutron doses of interest in radiotherapy. The technique, which utilizes calculated neutron fluence-to-kerma conversion factors, is based upon the combination of measurements with calibrated neptunium-237 and uranium-238 pulse fission chambers to obtain a response which matches the variation of kerma with neutron energy. The theoretical performance of a practical instrument has been assessed for a variety of neutron spectra to evaluate the spectrum dependence of the dosemeter. The overall systematic uncertainty using this absolute method of determining the neutron dose under charged particle equilibrium conditions is comparable to that encountered with ionization chamber techniques.

  1. Ionization chamber

    DOEpatents

    Walenta, Albert H.

    1981-01-01

    An ionization chamber has separate drift and detection regions electrically isolated from each other by a fine wire grid. A relatively weak electric field can be maintained in the drift region when the grid and another electrode in the chamber are connected to a high voltage source. A much stronger electric field can be provided in the detection region by connecting wire electrodes therein to another high voltage source. The detection region can thus be operated in a proportional mode when a suitable gas is contained in the chamber. High resolution output pulse waveforms are provided across a resistor connected to the detection region anode, after ionizing radiation enters the drift region and ionize the gas.

  2. The response of visco-elastic crust and mantle to the inflation/deflation of magma chamber

    NASA Astrophysics Data System (ADS)

    Yamasaki, T.

    2015-12-01

    It is important to quantitatively evaluate how magmatic activities at depth are reflected in geodetically (GPS and/or InSAR) observed surface deformation in order to distinguish magma-induced crustal deformation. This study employs 3-D finite element model to examine response of the linear Maxwell visco-elastic crust and mantle to a development of sill. Models with instantaneous and/or time-dependent inflation/deflation of sill at various depths in the crust have predicted geodetically detectable surface deformation, providing important constraints on spatio-temporal-scale of magmatic activities. Instantaneous inflation of sill in the crust causes the surface uplift. The amplitude and wavelength of the uplift are amplified for shallower and deeper inflations, respectively. The inflation occurred over a greater horizontal extent intensify both the amplitude and wavelength. The inflation-induced surface uplift would however abate with time by visco-elastic relaxation. Any signature of sill would disappear in ~ 50 - 100 times Maxwell relaxation time of the crust unless the inflation occurred within the uppermost layer that effectively acts as elastic layer. Time-dependent inflation accompanies with visco-elastic relaxation, and the inflation having occurred over the time-scale of ~ 50 - 100 times crustal relaxation time would provide insignificant signature at the surface, which in turn tells us that crustal deformation would reflect the development of magma chamber only if it has occurred in that time-scale. This study also has found that an ascent of magma into shallower depth may be recognised by an observation such that a horizontal extent over which the surface uplift is progressively intensified focusses into a narrower region.

  3. SU-E-T-448: On the Perturbation Factor P-cav of the Markus Parallel Plate Ion Chambers in Clinical Electron Beams, Monte Carlo Based Reintegration of An Historical Experiment

    SciTech Connect

    Voigts-Rhetz, P von; Zink, K

    2014-06-01

    Purpose: All present dosimetry protocols recommend well-guarded parallel-plate ion chambers for electron dosimetry. For the guard-less Markus chamber an energy dependent fluence perturbation correction pcav is given. This perturbation correction was experimentally determined by van der Plaetsen by comparison of the read-out of a Markus and a NACP chamber, which was assumed to be “perturbation-free”. Aim of the present study is a Monte Carlo based reiteration of this experiment. Methods: Detailed models of four parallel-plate chambers (Roos, Markus, NACP and Advanced Markus) were designed using the Monte Carlo code EGSnrc and placed in a water phantom. For all chambers the dose to the active volume filled with low density water was calculated for 13 clinical electron spectra (E{sub 0}=6-21 MeV) at the depth of maximum and at the reference depth under reference conditions. In all cases the chamber's reference point was positioned at the depth of measurement. Moreover, the dose to water DW was calculated in a small water voxel positioned at the same depth. Results: The calculated dose ratio D{sub NACP}/D{sub Markus}, which according to van der Plaetsen reflects the fluence perturbation correction of the Markus chamber, deviates less from unity than the values given by van der Plaetsen's but exhibits a similar energy dependence. The same holds for the dose ratios of the other well guarded chambers. But, in comparison to water, the Markus chamber reveals the smallest overall perturbation correction which is nearly energy independent at both investigated depths. Conclusion: The simulations principally confirm the energy dependence of the dose ratio D{sub NACP}/D{sub Markus} as published by van der Plaetsen. But, as shown by our simulations of the ratio D{sub W}/D{sub Markus}, the conclusion drawn in all dosimetry protocols is questionable: in contrast to all well-guarded chambers the guard-less Markus chamber reveals the smallest overall perturbation correction and

  4. Simulation of target response due to uranium ion beam impact

    NASA Astrophysics Data System (ADS)

    Richter, H.; Noah, E.; Aiginger, H.; Poljanc, K.

    2009-12-01

    Metal targets were irradiated at GSI with a highly focused uranium ion beam with a kinetic energy of 350MeV/u. Out of these targets two copper samples, that had been irradiated multiple times with a maximum intensity of 2.36 · 109 , were chosen for simulations. In order to characterize the behavior of the target under the load of the ion beam, FLUKA was used to generate the initial distribution of deposited energy which was in turn used as an input for ANSYS AUTODYN to calculate the dynamic response of the target. In the simulations of the first sample a good approximation of the so-called hydrodynamic tensile limit, the crucial parameter for target failure, was found to be -1.08 GPa. This acquired value was used for the simulation of the second sample which had been irradiated with two high-intensity shots. These simulations resulted in the full penetration of the sample which was in agreement with metallurgical examinations. This paper presents the performed simulations.

  5. Isotopic zonations in silicic magma chambers: conventional and ion-microprobe data from the late-Oligocene Questa caldera, northern New Mexico

    SciTech Connect

    Johnson, C.M.

    1985-01-01

    The >400km3 peralkaline high-SiO/sub 2/ rhyolite ash-flow tuff erupted form the Questa caldera is strongly zoned in trace elements and in initial 87Sr/86Sr, from 0.7082 at the top to 0.7123 at the base. This is accompanied by increasing abundance of zircons with inherited cores, as identified using the ANU SHRIMP ion-microprobe. Cores that are concordant at 1700, 100 and 1430 Ma occur within late-Oligocene zircons in the ash-flow tuff. Such inherited cores is best explained by a greater degree of assimilation of Precambrian roof rocks toward the top of the magma chamber prior to eruption. In contrast, element of Nd and delta 180 values are constant at -6 and +7, respectively. Mass-balance calculations using observed compositions of the Precambrian wall-rocks and the low Sr peralkaline magmas indicate that the amount of assimilation required is less than 15 percent. Peralkaline and metaluminous intrusions cogenetic with the ash flow tuff also have relatively constant element of Nd and delta 180 values of -6 and +7, but have initial 87Sr/86Sr between from 0.7077 to 0.7050. None of the intrusive bodies contain inherited zircons, in contrast with many other Tertiary granitic rocks in the western US. Comparison of isotopic zonations in magmas that are largely liquid with those in their solidified equivalents is important for distinguishing assimilation vs source effects, since the assimilation potential of volatile-rich, crystal-poor magmas is much different from that of the crystal-rich magmas that become plutons.

  6. SU-E-T-83: A Study On Evaluating the Directional Dependency of 2D Seven 29 Ion Chamber Array Clinically with Different IMRT Plans

    SciTech Connect

    Kumar, Syam; Aswathi, C.P.

    2015-06-15

    Purpose: To evaluate the directional dependency of 2D seven 29 ion chamber array clinically with different IMRT plans. Methods: 25 patients already treated with IMRT plans were selected for the study. Verification plans were created for each treatment plan in eclipse 10 treatment planning system using the AAA algorithm with the 2D array and the Octavius CT phantom. Verification plans were done 2 times for a single patient. First plan with real IMRT (plan-related approach) and second plan with zero degree gantry angle (field-related approach). Measurements were performed on a Varian Clinac-iX, linear accelerator equipped with a millennium 120 multileaf collimator. Fluence was measured for all the delivered plans and analyzed using the verisoft software. Comparison was done by selecting the fluence delivered in static gantry (zero degree gantry) versus IMRT with real gantry angles. Results: The gamma pass percentage is greater than 97 % for all IMRT delivered with zero gantry angle and between 95%–98% for real gantry angles. Dose difference between the TPS calculated and measured for IMRT delivered with zero gantry angle was found to be between (0.03 to 0.06Gy) and with real gantry angles between (0.02 to 0.05Gy). There is a significant difference between the gamma analysis between the zero degree and true angle with a significance of 0.002. Standard deviation of gamma pass percentage between the IMRT plans with zero gantry angle was 0.68 and for IMRT with true gantry angle was found to be 0.74. Conclusion: The gamma analysis for IMRT with zero degree gantry angles shows higher pass percentage than IMRT delivered with true gantry angles. Verification plans delivered with true gantry angles lower the verification accuracy when 2D array is used for measurement.

  7. Responses of soybeans and wheat to elevated CO2 in free-air and open top chamber systems

    Technology Transfer Automated Retrieval System (TEKTRAN)

    With increasing demand for agricultural products, more confidence is needed concerning impacts of rising atmospheric CO2 on crop yields. Despite debate about the merits of free-air CO2 enrichment (FACE) and open top chamber (OTC) systems, there has been only one reported experiment directly compari...

  8. SU-E-T-350: Effective Point of Measurement and Total Perturbation Correction P for Parallel-Plate Ion Chambers in High-Energy Photon Beams

    SciTech Connect

    Langner, N; Czarnecki, D; Voigts-Rhetz, P von; Zink, K

    2015-06-15

    Purpose: This paper aims to determine the effective point of measurement and the total perturbation correction p of parallel-plate chambers for clinical photon dosimetry. Methods: The effective point of measurement (EPOM) was calculated using the EGSnrc Monte Carlo code system with the EGSnrc user code egs- chamber. Depth dose curves of the ionization chambers were calculated in a water phantom for several high energy photon spectra (4, 6, 10, 15, 18 MV-X). Different normalization criterions (normalization to the maximum of the depth dose curve and normalization to the value in 10 cm depth) have been applied. The EPOM was determined by shifting the normalized depth dose curve of a small water voxel against the depth ionization curve until the disagreement (calculated by the root mean square deviation) reaches a minimum. In addition, the total perturbation correction p was calculated by the ratio of the dose to water and the product of the dose determined in the chamber and the water to air stopping power ratio. Results: The EPOM varied slightly depending on the chosen normalization criterion. For all chambers the necessary shift of the EPOM decreased linearly with increasing beam quality specifier TPR{sub 20/10}. For the Roos and NACP chamber, the results were positive suggesting that the chambers need to be shifted towards the focus. For the Markus chamber, the required shift was negative and for the Advanced Markus chamber partly negative and partly positive. The total perturbation correction p was almost independent of the depth. Only for regions below 1 cm the perturbation correction deviated significantly from unity. Conclusion: In the present study, the effective point of measurement and the total perturbation correction p was determined for four parallel-plate ionization chambers and five clinical relevant photon spectra. Applying the calculated EPOM, the residual perturbation correction p was mostly depth independent.

  9. Calibration and performance of a secondary emission chamber as a beam intensity monitor

    SciTech Connect

    Sivertz, M.; Chiang, I-H,; Rusek, A.

    2011-03-28

    We report on a study of the behavior of a secondary emission chamber (SEC). We show the dependence of the SEC signal on the charge and velocity of the primary beam for beams of protons, and heavy ions including Helium, Neon, Chlorine and Iron. We fill the SEC with a selection of different gases including Hydrogen, Helium, Nitrogen, Argon, and air, studying the SEC response when it is acting as an ion chamber. We also investigate the behavior of the SEC at intermediate pressures between 10{sup -8} torr and atmospheric pressure. The SEC uses thin conducting foils as the source and collector of electrons in a vacuum chamber. When charged particles traverse the vacuum chamber, they pass through a series of thin conducting foils, alternating anode and cathode. Ionization produced in the cathode foils travels across the intervening gap due to an applied high voltage and is collected on the anode foils. Electron production is very inefficient because most of the ionization in the foils remains trapped within the foil due to the short range of most delta-rays and the work function of the foil. It is this inefficiency that allows the SEC to operate at high dose rates and short pulse duration where the standard ion chambers cannot function reliably. The SEC was placed in the NSRL ion beam to receive a variety of heavy ion beams under different beam conditions. We used these ion beams to study the response of the SEC to different species of heavy ion, comparing with proton beams. We studied the response to beam of different energies, and as a function of different counting rate. We compared the behaviour of the SEC when operating under positive and negative high voltage. The SEC can operate as an ion chamber if it is filled with gas. We measured the response of the SEC when filled with a variety of gases, from Hydrogen to Helium, Nitrogen, Argon and air. The performance of the SEC as an ion chamber is compared with the standard NSRL ion chamber, QC3. By evacuating the SEC and

  10. Migration to new ampoule types for the NPL secondary standard ionisation chambers.

    PubMed

    Baker, M; Fenwick, A; Ferreira, K; Keightley, J; Johansson, L; Collins, S

    2014-05-01

    As the pre-calibrated sample containers used for activity assay in the two NPL secondary standards ionisation chambers are being phased out, suitable replacements have been identified. Characterisation checks have been carried out on the new ISO ampoules and a long-term recalibration schedule has been devised. Around 40 calibration factors have been determined so far and comparison of ion chamber responses for the two ampoule types showed variations of up to 7% for low energy photon emitting radionuclides.

  11. Liquid Wall Chambers

    SciTech Connect

    Meier, W R

    2011-02-24

    The key feature of liquid wall chambers is the use of a renewable liquid layer to protect chamber structures from target emissions. Two primary options have been proposed and studied: wetted wall chambers and thick liquid wall (TLW) chambers. With wetted wall designs, a thin layer of liquid shields the structural first wall from short ranged target emissions (x-rays, ions and debris) but not neutrons. Various schemes have been proposed to establish and renew the liquid layer between shots including flow-guiding porous fabrics (e.g., Osiris, HIBALL), porous rigid structures (Prometheus) and thin film flows (KOYO). The thin liquid layer can be the tritium breeding material (e.g., flibe, PbLi, or Li) or another liquid metal such as Pb. TLWs use liquid jets injected by stationary or oscillating nozzles to form a neutronically thick layer (typically with an effective thickness of {approx}50 cm) of liquid between the target and first structural wall. In addition to absorbing short ranged emissions, the thick liquid layer degrades the neutron flux and energy reaching the first wall, typically by {approx}10 x x, so that steel walls can survive for the life of the plant ({approx}30-60 yrs). The thick liquid serves as the primary coolant and tritium breeding material (most recent designs use flibe, but the earliest concepts used Li). In essence, the TLW places the fusion blanket inside the first wall instead of behind the first wall.

  12. Fast ionospheric response to enhanced activity in geospace: Ion feeding of the inner magnetotail

    SciTech Connect

    Daglis, I.A.; Axford, I.A.

    1996-03-01

    The authors look at the question of the ionosphere feeding ions into the magnetosphere/magnetotail, in response to magnetic storm activity, or coupling of the solar wind into the system. They are concerned with fast response, not the question of whether the ionosphere feeds ions in general. The dynamics which results in the inner magnetosphere in response to the input of cold ions from the ionosphere is of interest to the authors. They review recent and older data which has shed light on this question. They look at outflow data, and heating mechanisms for these cold ions, as well as the impact such ions may have on the dynamics of magnetic storms. They observe that fast feeding of ions out of the ionosphere may leave the inner magnetosphere heavily populated with heavy ions such as O{sup +}, which can have a definite impact on the dynamic development of the magnetosphere.

  13. Implementation of Gas Sampling Chamber and Measuring Hardware for Capnograph System Considering Thermal Noise Effect and Time Response Characteristics

    DTIC Science & Technology

    2007-11-02

    chamber, thermal background effect I. INTRODUCTION As a measuring method for a capnograph system that determines indirectly the level of pCO2 in a...The chopping frequency of an IR lamp corresponds to the sampling frequency for the continuous measurement of the CO2 gas concentration without aliasing...order MFB(multiple feedback) lowpass filter. Finally, the use of 240×64 graphic LCD makes it easy to continuously observe and measure the CO2 gas

  14. Ionization chamber dosimeter

    DOEpatents

    Renner, Tim R.; Nyman, Mark A.; Stradtner, Ronald

    1991-01-01

    A method for fabricating an ion chamber dosimeter collecting array of the type utilizing plural discrete elements formed on a uniform collecting surface which includes forming a thin insulating layer over an aperture in a frame having surfaces, forming a predetermined pattern of through holes in the layer, plating both surfaces of the layer and simultaneously tilting and rotating the frame for uniform plate-through of the holes between surfaces. Aligned masking and patterned etching of the surfaces provides interconnects between the through holes and copper leads provided to external circuitry.

  15. WE-EF-207-11: Energy and Depth Response of Thermoluminescent Dosimeters and Ionization Chambers in Water for Kilovoltage X-Ray Beams

    SciTech Connect

    Lawless, M; Palmer, B; DeWerd, L

    2015-06-15

    Purpose: To assess the effects of changes in beam quality on detector response in the kilovoltage energy range by modulating the x-ray tube voltage and the measurement depth in water. Methods: Measurements were performed with TLD-100 and TLD-100H thermoluminescent dosimeters and an A12 farmer-type ionization chamber. To assess the energy response of the detectors, irradiations were performed at a depth of 3 cm in a custom-built thin-window water phantom using the moderately filtered x-ray beams at the UWADCL (20 kVp-250 kVp) and a Co-60 beam.The x-ray beams and detectors were modeled using the EGSnrc Monte Carlo code. The model was validated by simulating dose to the collecting volume of an A12 farmer chamber and comparing it with measured A12 signal as a function of depth. Dose was tallied to each detector and to water for comparison with measurements. Simulations were used to calculate the predicted energy response, which was compared to the measured response of each detector. Dose to each detector and dose to water as a function of depth were also simulated. Results: Detector output per dose to water was found to deviate by up to 15%, 20% and 30% as a function of energy relative to Co-60 for the A12, TLD-100H and TLD-100, respectively. The EGSnrc simulations produced results similar to the measurements for ionization chambers, but discrepancies of up to 30% were observed for TLD-100H. Simulated detector response as a function of depth was found to vary by up to 3%. Conclusion: These results suggest that changes in beam quality in kilovoltage x-ray beams can have a significant impact on detector response. In-water detector response was found to differ from the previously investigated in-air response. Deviations in detector response as a function of depth were less significant, but could potentially cause dosimetric errors if ignored.

  16. Chamber Clearing First Principles Modeling

    SciTech Connect

    Loosmore, G

    2009-06-09

    LIFE fusion is designed to generate 37.5 MJ of energy per shot, at 13.3 Hz, for a total average fusion power of 500 MW. The energy from each shot is partitioned among neutrons ({approx}78%), x-rays ({approx}12%), and ions ({approx}10%). First wall heating is dominated by x-rays and debris because the neutron mean free path is much longer than the wall thickness. Ion implantation in the first wall also causes damage such as blistering if not prevented. To moderate the peak-pulse heating, the LIFE fusion chamber is filled with a gas (such as xenon) to reduce the peak-pulse heat load. The debris ions and majority of the x-rays stop in the gas, which re-radiates this energy over a longer timescale (allowing time for heat conduction to cool the first wall sufficiently to avoid damage). After a shot, because of the x-ray and ion deposition, the chamber fill gas is hot and turbulent and contains debris ions. The debris needs to be removed. The ions increase the gas density, may cluster or form aerosols, and can interfere with the propagation of the laser beams to the target for the next shot. Moreover, the tritium and high-Z hohlraum debris needs to be recovered for reuse. Additionally, the cryogenic target needs to survive transport through the gas mixture to the chamber center. Hence, it will be necessary to clear the chamber of the hot contaminated gas mixture and refill it with a cool, clean gas between shots. The refilling process may create density gradients that could interfere with beam propagation, so the fluid dynamics must be studied carefully. This paper describes an analytic modeling effort to study the clearing and refilling process for the LIFE fusion chamber. The models used here are derived from first principles and balances of mass and energy, with the intent of providing a first estimate of clearing rates, clearing times, fractional removal of ions, equilibrated chamber temperatures, and equilibrated ion concentrations for the chamber. These can be used

  17. Ion Trapping with Fast-Response Ion-Selective Microelectrodes Enhances Detection of Extracellular Ion Channel Gradients

    PubMed Central

    Messerli, Mark A.; Collis, Leon P.; Smith, Peter J.S.

    2009-01-01

    Previously, functional mapping of channels has been achieved by measuring the passage of net charge and of specific ions with electrophysiological and intracellular fluorescence imaging techniques. However, functional mapping of ion channels using extracellular ion-selective microelectrodes has distinct advantages over the former methods. We have developed this method through measurement of extracellular K+ gradients caused by efflux through Ca2+-activated K+ channels expressed in Chinese hamster ovary cells. We report that electrodes constructed with short columns of a mechanically stable K+-selective liquid membrane respond quickly and measure changes in local [K+] consistent with a diffusion model. When used in close proximity to the plasma membrane (<4 μm), the ISMs pose a barrier to simple diffusion, creating an ion trap. The ion trap amplifies the local change in [K+] without dramatically changing the rise or fall time of the [K+] profile. Measurement of extracellular K+ gradients from activated rSlo channels shows that rapid events, 10–55 ms, can be characterized. This method provides a noninvasive means for functional mapping of channel location and density as well as for characterizing the properties of ion channels in the plasma membrane. PMID:19217875

  18. ION SOURCE FOR A CALUTRON

    DOEpatents

    Lofgren, E.J.

    1959-04-14

    This patcnt relates to calutron devices and deals particularly with the mechanism used to produce the beam of ions wherein a charge material which is a vapor at room temperature is used. A charge container located outside the tank is connected through several conduits to various points along the arc chamber of the ion source. In addition, the rate of flow of the vapor to the arc chamber is controlled by a throttle valve in each conduit. By this arrangement the arc can be regulated accurately and without appreciable time lag, inasmuch as the rate of vapor flow is immediately responsive to the manipulation of the throttle valves.

  19. Transgenic Bacillus thuringiensis (Bt) cotton (Gossypium hirsutum) allomone response to cotton aphid, Aphis gossypii, in a closed-dynamics CO(2) chamber (CDCC).

    PubMed

    Wu, Gang; Chen, Fa Jun; Ge, Feng; Sun, Yu-Cheng

    2007-11-01

    Allocation of allomones of transgenic Bacillus thuringiensis Gossypium hirsutum (Bt cotton) (cv. GK-12) and non-Bt-transgenic cotton (cv. Simian-3) grown in elevated CO(2) in response to infestation by cotton aphid, Aphis gossypii Glover, was studied in a closed-dynamics CO(2) chamber. Significant increases in foliar condensed tannin and carbon/nitrogen ratio for GK-12 and Simian-3 were observed in elevated CO(2) relative to ambient CO(2,) as partially supported by the carbon nutrient balance hypothesis, owing to limiting nitrogen and excess carbon in cotton plants in response to elevated CO(2). The CO(2) level significantly influenced the foliar nutrients and allomones in the cotton plants. Aphid infestation significantly affected foliar nitrogen and allomone compounds in the cotton plants. Allomone allocation patterns in transgenic Bt cotton infested by A. gossypii may have broader implications across a range of plant and herbivorous insects as CO(2) continues to rise.

  20. Non-Targeted Effects and the Dose Response for Heavy Ion Tumorigenesis

    NASA Technical Reports Server (NTRS)

    Chappell, Lori J.; Cucinotta, Francis A.

    2010-01-01

    There is no human epidemiology data available to estimate the heavy ion cancer risks experienced by astronauts in space. Studies of tumor induction in mice are a necessary step to estimate risks to astronauts. Previous experimental data can be better utilized to model dose response for heavy ion tumorigenesis and plan future low dose studies.

  1. Identification of a calcineurin-independent pathway required for sodium ion stress response in Saccharomyces cerevisiae.

    PubMed Central

    Ganster, R W; McCartney, R R; Schmidt, M C

    1998-01-01

    The calcium-dependent protein phosphatase calcineurin plays an essential role in ion homeostasis in yeast. In this study, we identify a parallel ion stress response pathway that is independent of the calcineurin signaling pathway. Cells with null alleles in both STD1 and its homologue, MTH1, manifest numerous phenotypes observed in calcineurin mutants, including sodium, lithium, manganese, and hydroxyl ion sensitivity, as well as alpha factor toxicity. Furthermore, increased gene dosage of STD1 suppresses the ion stress phenotypes in calcineurin mutants and confers halotolerance in wild-type cells. However, Std1p functions in a calcineurin-independent ion stress response pathway, since a std1 mth1 mutant is FK506 sensitive under conditions of ion stress. Mutations in other genes known to regulate gene expression in response to changes in glucose concentration, including SNF3, RGT2, and SNF5, also affect cell growth under ion stress conditions. Gene expression studies indicate that the regulation of HAL1 and PMR2 expression is affected by STD1 gene dosage. Taken together, our data demonstrate that response to ion stress requires the participation of both calcineurin-dependent and -independent pathways. PMID:9725828

  2. Ionospheric Plasma Outflow in Response to Transverse Ion Heating: Self-Consistent Macroscopic Treatment

    NASA Technical Reports Server (NTRS)

    Singh, Nagendra

    1995-01-01

    During the grant period starting July 1, 1994, our major effort has been on the following two problems: (1) Temporal behavior of heavy Oxygen ion outflow in response to a transverse heating event; and (2) Continued effort on ion heating by lower hybrid waves. We briefly describe here the research performed under these topics.

  3. Effect of nebulizer/spray chamber interfaces on simultaneous, axial view inductively coupled plasma optical emission spectrometry for the direct determination of As and Se species separated by ion exchange high-performance liquid chromatography

    NASA Astrophysics Data System (ADS)

    Gettar, Raquel T.; Smichowski, Patricia; Garavaglia, Ricardo N.; Farías, Silvia; Batistoni, Daniel A.

    2005-06-01

    Different nebulizer/expansion chamber combinations were evaluated to assess their performance for sample introduction in the direct coupling with an axial view inductively coupled plasma multielement spectrometer for on-line determination of As and Se species previously separated by ion exchange-high performance liquid chromatography. The column effluents were injected into the plasma without prior derivatization. The instrument operation software was adapted for data acquisition and processing to allow multi-wavelength recording of the transient chromatographic peaks. After optimization of the chromatographic operating conditions, separation of mixtures of inorganic As and Se species, and of inorganic and two organic As species (monomethylarsonic and dimethylarsinic acids), was achieved with excellent resolution. Species discrimination from mixtures of As and Se oxyanions was further improved by the simultaneous element detection at specific analytical wavelengths. Three nebulizers and three spray chambers, employed in seven combinations, were tested as interfaces. Concentric nebulizers associated to a glass cyclonic chamber appear most suitable regarding sensitivity and signal to noise ratio. Measured element detection limits (3 σ) were around 10 ng ml - 1 for all the species considered, making the method a viable alternative to similar procedures that employ volatile hydride generation previous to sample injection into the plasma. Analytical recoveries both for inorganic and organic species ranged between 92 and 107%. The method was demonstrated to be apt for the analysis of surface waters potentially subjected to natural contamination with arsenic.

  4. Evaluation of physiological and biochemical responses of two rice (Oryza sativa L.) cultivars to ambient air pollution using open top chambers at a rural site in India.

    PubMed

    Rai, Richa; Agrawal, Madhoolika

    2008-12-15

    Air pollutant concentrations are rising in India, causing potential threats to crop production. As air pollutants are known to interfere with physiological processes, this study was conducted to assess the relative responses of physiological and biochemical characteristics of two cultivars of rice (Oryza sativa L. cv. Saurabh 950 and NDR 97) leading to variable yield responses. Twelve hour monitoring of ambient concentrations of SO2, NO2 and O3 in filtered chambers (FCs), non-filtered chambers (NFCs) and open plots (OPs) showed that O3 was the main pollutant at the experimental site. Ozone concentrations often exceeded 40 ppb during anthesis but not during the vegetative growth period. Photosynthetic rate (Ps), stomatal conductance (g(s)) and Fv/Fm ratio, superoxide dismutase (SOD) and peroxidase (POD) activities and photosynthetic pigments, ascorbic acid, total phenolics and protein contents were assessed at different developmental stages and yield of grains were quantified. Lipid peroxidation, SOD and POD activities, ascorbic acid and total phenolics were higher, whereas Ps, g(s), Fv/Fm ratio and contents of protein and photosynthetic pigment were lower in plants of NFCs as compared to FCs. Yield decreased significantly in both cultivars grown in NFCs. NDR 97 showed less reductions in physiological characteristics, photosynthetic pigments and protein, but a greater increase in the antioxidative defense system as compared to Saurabh 950. Yield reduction was higher in NDR 97 than in Saurabh 950. This suggested that NDR 97 utilized more photosynthate in maintaining the metabolic machinery against O3 stress leading to lower translocation of photosynthate to reproductive parts. The study concluded that under natural field conditions, physiological and biochemical responses of plants varied with pollutant concentrations leading to different translocation strategies in plants, modifying their yield responses. NDR 97, a fast growing and high yielding cultivar was more

  5. Neutron detection via bubble chambers.

    PubMed

    Jordan, D V; Ely, J H; Peurrung, A J; Bond, L J; Collar, J I; Flake, M; Knopf, M A; Pitts, W K; Shaver, M; Sonnenschein, A; Smart, J E; Todd, L C

    2005-01-01

    Research investigating the application of pressure-cycled bubble chambers to fast neutron detection is described. Experiments with a Halon-filled chamber showed clear sensitivity to an AmBe neutron source and insensitivity to a (137)Cs gamma source. Bubble formation was documented using high-speed photography, and a ceramic piezo-electric transducer element registered the acoustic signature of bubble formation. In a second set of experiments, the bubble nucleation response of a Freon-134a chamber to an AmBe neutron source was documented with high-speed photography.

  6. Leakage of K+ ions from Staphylococcus aureus in response to tea tree oil.

    PubMed

    Hada, Toshiko; Inoue, Yoshihiro; Shiraishi, Akiko; Hamashima, Hajime

    2003-06-01

    The leakage of K(+) ions from Staphylococcus aureus in response to tea tree oil (TTO) was investigated with an ion-selective electrode. The amount of leaked K(+) ions and the rate of leakage of K(+) ions induced by TTO were dependent on the concentration of TTO. Measurements of initial rates required less time than measurements of total amounts and provided an index of the interaction between TTO and the cell membrane. Thus, the initial rate of leakage might be a more useful measure of the antibacterial activity of TTO than the total amount.

  7. Modeling and validation of single-chamber microbial fuel cell cathode biofilm growth and response to oxidant gas composition

    SciTech Connect

    Ou, Shiqi; Zhao, Yi; Aaron, Douglas S.; Regan, John M.; Mench, Matthew M.

    2016-08-15

    This work describes experiments and computational simulations to analyze single-chamber, air-cathode microbial fuel cell (MFC) performance and cathodic limitations in terms of current generation, power output, mass transport, biomass competition, and biofilm growth. Steady-state and transient cathode models were developed and experimentally validated. Two cathode gas mixtures were used to explore oxygen transport in the cathode: the MFCs exposed to a helium-oxygen mixture (heliox) produced higher current and power output than the group of MFCs exposed to air or a nitrogen-oxygen mixture (nitrox), indicating a dependence on gas-phase transport in the cathode. Multi-substance transport, biological reactions, and electrochemical reactions in a multi-layer and multi-biomass cathode biofilm were also simulated in a transient model. The transient model described biofilm growth over 15 days while providing insight into mass transport and cathodic dissolved species concentration profiles during biofilm growth. Lastly, simulation results predict that the dissolved oxygen content and diffusion in the cathode are key parameters affecting the power output of the air-cathode MFC system, with greater oxygen content in the cathode resulting in increased power output and fully-matured biomass.

  8. Modeling and validation of single-chamber microbial fuel cell cathode biofilm growth and response to oxidant gas composition

    DOE PAGES

    Ou, Shiqi; Zhao, Yi; Aaron, Douglas S.; ...

    2016-08-15

    This work describes experiments and computational simulations to analyze single-chamber, air-cathode microbial fuel cell (MFC) performance and cathodic limitations in terms of current generation, power output, mass transport, biomass competition, and biofilm growth. Steady-state and transient cathode models were developed and experimentally validated. Two cathode gas mixtures were used to explore oxygen transport in the cathode: the MFCs exposed to a helium-oxygen mixture (heliox) produced higher current and power output than the group of MFCs exposed to air or a nitrogen-oxygen mixture (nitrox), indicating a dependence on gas-phase transport in the cathode. Multi-substance transport, biological reactions, and electrochemical reactions inmore » a multi-layer and multi-biomass cathode biofilm were also simulated in a transient model. The transient model described biofilm growth over 15 days while providing insight into mass transport and cathodic dissolved species concentration profiles during biofilm growth. Lastly, simulation results predict that the dissolved oxygen content and diffusion in the cathode are key parameters affecting the power output of the air-cathode MFC system, with greater oxygen content in the cathode resulting in increased power output and fully-matured biomass.« less

  9. Modeling and validation of single-chamber microbial fuel cell cathode biofilm growth and response to oxidant gas composition

    NASA Astrophysics Data System (ADS)

    Ou, Shiqi; Zhao, Yi; Aaron, Douglas S.; Regan, John M.; Mench, Matthew M.

    2016-10-01

    This work describes experiments and computational simulations to analyze single-chamber, air-cathode microbial fuel cell (MFC) performance and cathodic limitations in terms of current generation, power output, mass transport, biomass competition, and biofilm growth. Steady-state and transient cathode models were developed and experimentally validated. Two cathode gas mixtures were used to explore oxygen transport in the cathode: the MFCs exposed to a helium-oxygen mixture (heliox) produced higher current and power output than the group of MFCs exposed to air or a nitrogen-oxygen mixture (nitrox), indicating a dependence on gas-phase transport in the cathode. Multi-substance transport, biological reactions, and electrochemical reactions in a multi-layer and multi-biomass cathode biofilm were also simulated in a transient model. The transient model described biofilm growth over 15 days while providing insight into mass transport and cathodic dissolved species concentration profiles during biofilm growth. Simulation results predict that the dissolved oxygen content and diffusion in the cathode are key parameters affecting the power output of the air-cathode MFC system, with greater oxygen content in the cathode resulting in increased power output and fully-matured biomass.

  10. Portable Hyperbaric Chamber

    NASA Technical Reports Server (NTRS)

    Schneider, William C. (Inventor); Locke, James P. (Inventor); DeLaFuente, Horacio (Inventor)

    2001-01-01

    A portable, collapsible hyperbaric chamber was developed. A toroidal inflatable skeleton provides initial structural support for the chamber, allowing the attendant and/or patient to enter the chamber. Oval hatches mate against bulkhead rings, and the hyperbaric chamber is pressurized. The hatches seal against an o-ring, and the internal pressure of the chamber provides the required pressure against the hatch to maintain an airtight seal. In the preferred embodiment, the hyperbaric chamber has an airlock to allow the attendant to enter and exit the patient chamber during treatment. Visual communication is provided through portholes in the patient and/or airlock chamber. Life monitoring and support systems are in communication with the interior of the hyperbaric chamber and/or airlock chamber through conduits and/or sealed feed-through connectors into the hyperbaric chamber.

  11. Interaction of (12)C ions with the mouse retinal response to light.

    PubMed

    Carozzo, Simone; Ball, Sherry L; Narici, Livio; Schardt, Dieter; Sannita, Walter G

    2015-06-26

    Astronauts in orbit reported phosphenes varying in shape and orientation across the visual field; incidence was correlated with the radiation flux. Patients with skull tumors treated by (12)C ions and volunteers whose posterior portion of the eye was exposed to highly ionizing particles in early studies reported comparable percepts. An origin in radiation activating the visual system is suggested. Bursts (∼ 4 ms) of (12)C ions evoked electrophysiological mass responses comparable to those to light in the retina of anesthetized wild-type mice at threshold flux intensities consistent with the incidence observed in humans. The retinal response amplitude increased in mice with ion intensity to a maximum at ∼ 2000 ions/burst, to decline at higher intensities; the inverted-U relationship suggests complex effects on retinal structures. Here, we show that bursts of (12)C ions presented simultaneously to white light stimuli reduced the presynaptic mass response to light in the mouse retina, while increasing the postsynaptic retinal and cortical responses amplitude and the phase-locking to stimulus of cortical low frequency and gamma (∼ 25-45 Hz) responses. These findings suggest (12)C ions to interfere with, rather than mimicking the light action on photoreceptors; a parallel action on other retinal structures/mechanisms resulting in cortical activation is conceivable. Electrophysiological visual testing appears applicable to monitor the radiation effects and in designing countermeasures to prevent functional visual impairment during operations in space.

  12. ION SOURCE

    DOEpatents

    Bell, W.A. Jr.; Love, L.O.; Prater, W.K.

    1958-01-28

    An ion source is presented capable of producing ions of elements which vaporize only at exceedingly high temperatures, i.e.,--1500 degrees to 3000 deg C. The ion source utilizes beams of electrons focused into a first chamber housing the material to be ionized to heat the material and thereby cause it to vaporize. An adjacent second chamber receives the vaporized material through an interconnecting passage, and ionization of the vaporized material occurs in this chamber. The ionization action is produced by an arc discharge sustained between a second clectron emitting filament and the walls of the chamber which are at different potentials. The resultant ionized material egresses from a passageway in the second chamber. Using this device, materials which in the past could not be processed in mass spectometers may be satisfactorily ionized for such applications.

  13. Diogene pictorial drift chamber

    SciTech Connect

    Gosset, J.

    1984-01-01

    A pictorial drift chamber, called DIOGENE, has been installed at Saturne in order to study central collisions of high energy heavy ions. It has been adapted from the JADE internal detector, with two major differences to be taken into account. First, the center-of-mass of these collisions is not identical to the laboratory reference frame. Second, the energy loss and the momentum ranges of the particles to be detected are different from the ones in JADE. It was also tried to keep the cost as small as possible, hence the choice of minimum size and minimum number of sensitive wires. Moreover the wire planes are shifted from the beam axis: this trick helps very much to quickly reject the bad tracks caused by the ambiguity of measuring drift distances (positive or negative) through times (always positive).

  14. Soil and ecosystem respiration responses to grazing, watering and experimental warming chamber treatments across topographical gradients in northern Mongolia

    PubMed Central

    Sharkhuu, Anarmaa; Plante, Alain F.; Enkhmandal, Orsoo; Gonneau, Cédric; Casper, Brenda B.; Boldgiv, Bazartseren; Petraitis, Peter S.

    2017-01-01

    Globally, soil respiration is one of the largest fluxes of carbon to the atmosphere and is known to be sensitive to climate change, representing a potential positive feedback. We conducted a number of field experiments to study independent and combined impacts of topography, watering, grazing and climate manipulations on bare soil and vegetated soil (i.e., ecosystem) respiration in northern Mongolia, an area known to be highly vulnerable to climate change and overgrazing. Our results indicated that soil moisture is the most important driving factor for carbon fluxes in this semi-arid ecosystem, based on smaller carbon fluxes under drier conditions. Warmer conditions did not result in increased respiration. Although the system has local topographical gradients in terms of nutrient, moisture availability and plant species, soil respiration responses to OTC treatments were similar on the upper and lower slopes, implying that local heterogeneity may not be important for scaling up the results. In contrast, ecosystem respiration responses to OTCs differed between the upper and the lower slopes, implying that the response of vegetation to climate change may override microbial responses. Our results also showed that light grazing may actually enhance soil respiration while decreasing ecosystem respiration, and grazing impact may not depend on climate change. Overall, our results indicate that soil and ecosystem respiration in this semi-arid steppe are more sensitive to precipitation fluctuation and grazing pressure than to temperature change. PMID:28239190

  15. Soil and ecosystem respiration responses to grazing, watering and experimental warming chamber treatments across topographical gradients in northern Mongolia.

    PubMed

    Sharkhuu, Anarmaa; Plante, Alain F; Enkhmandal, Orsoo; Gonneau, Cédric; Casper, Brenda B; Boldgiv, Bazartseren; Petraitis, Peter S

    2016-05-01

    Globally, soil respiration is one of the largest fluxes of carbon to the atmosphere and is known to be sensitive to climate change, representing a potential positive feedback. We conducted a number of field experiments to study independent and combined impacts of topography, watering, grazing and climate manipulations on bare soil and vegetated soil (i.e., ecosystem) respiration in northern Mongolia, an area known to be highly vulnerable to climate change and overgrazing. Our results indicated that soil moisture is the most important driving factor for carbon fluxes in this semi-arid ecosystem, based on smaller carbon fluxes under drier conditions. Warmer conditions did not result in increased respiration. Although the system has local topographical gradients in terms of nutrient, moisture availability and plant species, soil respiration responses to OTC treatments were similar on the upper and lower slopes, implying that local heterogeneity may not be important for scaling up the results. In contrast, ecosystem respiration responses to OTCs differed between the upper and the lower slopes, implying that the response of vegetation to climate change may override microbial responses. Our results also showed that light grazing may actually enhance soil respiration while decreasing ecosystem respiration, and grazing impact may not depend on climate change. Overall, our results indicate that soil and ecosystem respiration in this semi-arid steppe are more sensitive to precipitation fluctuation and grazing pressure than to temperature change.

  16. Interferometric pump-probe characterization of the nonlocal response of optically transparent ion implanted polymers

    NASA Astrophysics Data System (ADS)

    Stefanov, Ivan L.; Hadjichristov, Georgi B.

    2012-03-01

    Optical interferometric technique is applied to characterize the nonlocal response of optically transparent ion implanted polymers. The thermal nonlinearity of the ion-modified material in the near-surface region is induced by continuous wave (cw) laser irradiation at a relatively low intensity. The interferometry approach is demonstrated for a subsurface layer of a thickness of about 100 nm formed in bulk polymethylmethacrylate (PMMA) by implantation with silicon ions at an energy of 50 keV and fluence in the range 1014-1017 cm-2. The laser-induced thermooptic effect in this layer is finely probed by interferometric imaging. The interference phase distribution in the plane of the ion implanted layer is indicative for the thermal nonlinearity of the near-surface region of ion implanted optically transparent polymeric materials.

  17. Protein-responsive assemblies from catechol-metal ion supramolecular coordination.

    PubMed

    Yuan, C; Chen, J; Yu, S; Chang, Y; Mao, J; Xu, Y; Luo, W; Zeng, B; Dai, L

    2015-03-21

    Supramolecular self-assembly driven by catechol-metal ion coordination has gained great success in the fabrication of functional materials including adhesives, capsules, coatings and hydrogels. However, this route has encountered a great challenge in the construction of nanoarchitectures in the absence of removable templates, because of the uncontrollable crosslinking of catechol-metal ion coordination. Herein, we show that a supramolecular approach, combining both catechol-metal ion coordination and polymer self-assembly together, can organize polymers into hybrid nanoassemblies ranging from solid particles, homogeneous vesicles to Janus vesicles. Without the introduction of a specific binding ligand or complicated molecular design, these assemblies can totally disassemble in response to proteins. UV/vis absorption, fluorescence quenching and recovery investigations have confirmed that proteins can seize metal ions from the hybrid nanoassemblies, thus causing the degradation of catechol-metal ion coordination networks.

  18. Charge exchange molecular ion source

    DOEpatents

    Vella, Michael C.

    2003-06-03

    Ions, particularly molecular ions with multiple dopant nucleons per ion, are produced by charge exchange. An ion source contains a minimum of two regions separated by a physical barrier and utilizes charge exchange to enhance production of a desired ion species. The essential elements are a plasma chamber for production of ions of a first species, a physical separator, and a charge transfer chamber where ions of the first species from the plasma chamber undergo charge exchange or transfer with the reactant atom or molecules to produce ions of a second species. Molecular ions may be produced which are useful for ion implantation.

  19. Thickness dependence of surface plasmon resonance sensor response for metal ion detection

    NASA Astrophysics Data System (ADS)

    Jung, Seung-A.; Lee, Taek-Sung; Kim, Won Mok; Lee, Kyeong-Seok; Jeong, Doo Seok; Lee, Wook Seong; Kim, Inho

    2013-08-01

    Surface plasmon resonance (SPR) sensor is one of the most viable technologies for portable and highly sensitive sensing in clinical and environmental applications. A lot of research on SPR sensors based on plasticized polyvinyl chloride (PVC) sensing layers for detection of various metal ions has been well reported, but a study on their correlation between sensing layer thickness and sensor response has been rarely done. The purpose of this study is to investigate thickness dependence of sensing layers on the response time and the sensitivity of SPR sensors based on plasticized PVC. Calcium ionophore was incorporated in the sensing layers for calcium ion detection. Our experimental results showed that thicker sensing layers exhibited higher sensitivity and wider detection range but longer response time. We discussed metal ion diffusion in plasticized sensing layers by correlating numerical calculations with experimental ones in order to understand temporal response of our SPR sensor. The response time also relied on the flow rate of calcium ion solutions, indicating that metal ion diffusion in bulk media is one of the limiting factors.

  20. Control Effect of a Large Geological Discontinuity on the Seismic Response and Stability of Underground Rock Caverns: A Case Study of the Baihetan #1 Surge Chamber

    NASA Astrophysics Data System (ADS)

    Cui, Zhen; Sheng, Qian; Leng, Xianlun

    2016-06-01

    In this paper, the seismic stability of the #1 surge chamber of the Baihetan hydropower plant, which is influenced by a large dominating geological discontinuity [the interlayer shear weakness zone (ISWZ) C2)], is studied. An advanced, nonlinear, continuously yielding (CY) model was adopted to describe the complex mechanical properties of ISWZ C2. This model considers a power function type, normal stress dependent behavior and the progressive damage that occurred during shear tests. The applicability of the CY model is proved via a comparison with field test results and the theoretical solution. Verification work was conducted in 3DEC code to show that the 3DEC software is suitable for implementing this model. Three ground motion waveforms were utilized to conduct a seismic analysis of the #1 surge chamber after a special response spectrum matching process. The seismic analysis confirmed the control effect of ISWZ C2 on the seismic stability of the cavern. The majority of the cavern's seismic displacement consists of elastic body movement, while the plastic deformation is relatively limited. Further, most of the deformations were caused by the contact deformation of C2. For the contact deformation of C2, the magnitude of permanent shear deformation is larger than that of the normal deformation. The magnitude of permanent shear deformation is more notable along the strike direction of C2, and the permanent normal displacement n of C2 mainly occurs along the dip direction of C2. Finally, the seismic stability of the cavern is assessed via the overload method. The seismic safety factor of the cavern is approximately 2-3.

  1. A numerical model of initial recombination for high-LET irradiation: Application to liquid-filled ionization chambers

    NASA Astrophysics Data System (ADS)

    Aguiar, P.; Pardo-Montero, J.

    2016-02-01

    In this paper we present a numerical model of initial recombination in media irradiated with high linear energy transfer (LET) ions, which relies on an amorphous track model of ionization of high LET particles, and diffusion, drift and recombination of ionized charge carriers. The model has fundamental applications for the study of recombination in non-polar liquids, as well as practical ones, like in modelling hadrontherapy dosimetry with ionization chambers. We have used it to study the response of liquid-filled ionization chambers to hadrontherapy beams: dependence of initial recombination on ion species, energy and applied external electric field.

  2. Calibration of BAS-TR image plate response to high energy (3-300 MeV) carbon ions

    NASA Astrophysics Data System (ADS)

    Doria, D.; Kar, S.; Ahmed, H.; Alejo, A.; Fernandez, J.; Cerchez, M.; Gray, R. J.; Hanton, F.; MacLellan, D. A.; McKenna, P.; Najmudin, Z.; Neely, D.; Romagnani, L.; Ruiz, J. A.; Sarri, G.; Scullion, C.; Streeter, M.; Swantusch, M.; Willi, O.; Zepf, M.; Borghesi, M.

    2015-12-01

    The paper presents the calibration of Fuji BAS-TR image plate (IP) response to high energy carbon ions of different charge states by employing an intense laser-driven ion source, which allowed access to carbon energies up to 270 MeV. The calibration method consists of employing a Thomson parabola spectrometer to separate and spectrally resolve different ion species, and a slotted CR-39 solid state detector overlayed onto an image plate for an absolute calibration of the IP signal. An empirical response function was obtained which can be reasonably extrapolated to higher ion energies. The experimental data also show that the IP response is independent of ion charge states.

  3. Intrinsic slow charge response in the perovskite solar cells: Electron and ion transport

    SciTech Connect

    Shi, Jiangjian; Xu, Xin; Zhang, Huiyin; Luo, Yanhong; Li, Dongmei; Meng, Qingbo

    2015-10-19

    The intrinsic charge response and hysteresis characteristic in the perovskite solar cell has been investigated by an electrically modulated transient photocurrent technology. An ultraslow charge response process in the timescale of seconds is observed, which can be well explained by the ion migration in the perovskite CH{sub 3}NH{sub 3}PbI{sub 3} film driven by multiple electric fields derived from the heterojunction depletion charge, the external modulation, and the accumulated ion charge. Furthermore, theoretical calculation of charge transport reveals that the hysteresis behavior is also significantly influenced by the interfacial charge extraction velocity and the carrier transport properties inside the cell.

  4. Sensitive detection of copper ions via ion-responsive fluorescence quenching of engineered porous silicon nanoparticles

    NASA Astrophysics Data System (ADS)

    Hwang, Jangsun; Hwang, Mintai P.; Choi, Moonhyun; Seo, Youngmin; Jo, Yeonho; Son, Jaewoo; Hong, Jinkee; Choi, Jonghoon

    2016-10-01

    Heavy metal pollution has been a problem since the advent of modern transportation, which despite efforts to curb emissions, continues to play a critical role in environmental pollution. Copper ions (Cu2+), in particular, are one of the more prevalent metals that have widespread detrimental ramifications. From this perspective, a simple and inexpensive method of detecting Cu2+ at the micromolar level would be highly desirable. In this study, we use porous silicon nanoparticles (NPs), obtained via anodic etching of Si wafers, as a basis for undecylenic acid (UDA)- or acrylic acid (AA)-mediated hydrosilylation. The resulting alkyl-terminated porous silicon nanoparticles (APS NPs) have enhanced fluorescence stability and intensity, and importantly, exhibit [Cu2+]-dependent quenching of fluorescence. After determining various aqueous sensing conditions for Cu2+, we demonstrate the use of APS NPs in two separate applications – a standard well-based paper kit and a portable layer-by-layer stick kit. Collectively, we demonstrate the potential of APS NPs in sensors for the effective detection of Cu2+.

  5. Sensitive detection of copper ions via ion-responsive fluorescence quenching of engineered porous silicon nanoparticles

    PubMed Central

    Hwang, Jangsun; Hwang, Mintai P.; Choi, Moonhyun; Seo, Youngmin; Jo, Yeonho; Son, Jaewoo; Hong, Jinkee; Choi, Jonghoon

    2016-01-01

    Heavy metal pollution has been a problem since the advent of modern transportation, which despite efforts to curb emissions, continues to play a critical role in environmental pollution. Copper ions (Cu2+), in particular, are one of the more prevalent metals that have widespread detrimental ramifications. From this perspective, a simple and inexpensive method of detecting Cu2+ at the micromolar level would be highly desirable. In this study, we use porous silicon nanoparticles (NPs), obtained via anodic etching of Si wafers, as a basis for undecylenic acid (UDA)- or acrylic acid (AA)-mediated hydrosilylation. The resulting alkyl-terminated porous silicon nanoparticles (APS NPs) have enhanced fluorescence stability and intensity, and importantly, exhibit [Cu2+]-dependent quenching of fluorescence. After determining various aqueous sensing conditions for Cu2+, we demonstrate the use of APS NPs in two separate applications – a standard well-based paper kit and a portable layer-by-layer stick kit. Collectively, we demonstrate the potential of APS NPs in sensors for the effective detection of Cu2+. PMID:27752120

  6. Species- and chamber-specific responses of 12 kDa FK506-binding protein to temperature in fish heart.

    PubMed

    Korajoki, Hanna; Vornanen, Matti

    2014-04-01

    The sarcoplasmic reticulum (SR) Ca(2+) release channel or ryanodine receptor (RyR) of the vertebrate heart is regulated by the FK506-binding proteins, FKBP12 and FKBP12.6. This study examines whether temperature-related changes in the SR function of fish hearts are associated with changes in FKBP12 expression. For this purpose, a polyclonal antibody against trout FKBP12 was used to compare FKPB12 expression in cold-acclimated (4 °C, CA) and warm-acclimated (18 °C, WA) rainbow trout (Oncorhynchus mykiss), burbot (Lota lota) and crucian carp (Carassius carassius) hearts. FKBP12 expression was modulated in a species- and tissue-specific manner. Temperature acclimation affected FKBP12 expression only in atrial tissue. Changes in the ventricular FKBP12 expression were not detected in any of the fish species. In the atria of rainbow trout and crucian carp, temperature acclimation produced opposite thermal responses: FKBP12 increased in the trout atrium and decreased in the crucian carp atrium under cold acclimation. In the burbot heart, chronic temperature changes did not affect cardiac FKBP12 levels. Expression of FKBP12 mRNA in rainbow trout and crucian carp hearts suggests that the transcript levels are higher in the ventricle than in the atrium and are elevated by cold acclimation in trout, but not in crucian carp. Since FKBP12 is known to increase the Ca(2+) sensitivity of cardiac RyRs and thereby the opening frequency of the Ca(2+) release channels, temperature-related changes in FKBP12 expression may modify the SR function in excitation-contraction coupling. The cold-induced increase in FKBP12 in the trout atrium and decrease in the crucian carp atrium are consistent with the previously noted increase and decrease, respectively, of SR Ca(2+) stores in cardiac contraction in these species.

  7. Utilizing Chamber Data for Developing and Validating Climate Change Models

    NASA Technical Reports Server (NTRS)

    Monje, Oscar

    2012-01-01

    Controlled environment chambers (e.g. growth chambers, SPAR chambers, or open-top chambers) are useful for measuring plant ecosystem responses to climatic variables and CO2 that affect plant water relations. However, data from chambers was found to overestimate responses of C fluxes to CO2 enrichment. Chamber data may be confounded by numerous artifacts (e.g. sidelighting, edge effects, increased temperature and VPD, etc) and this limits what can be measured accurately. Chambers can be used to measure canopy level energy balance under controlled conditions and plant transpiration responses to CO2 concentration can be elucidated. However, these measurements cannot be used directly in model development or validation. The response of stomatal conductance to CO2 will be the same as in the field, but the measured response must be recalculated in such a manner to account for differences in aerodynamic conductance, temperature and VPD between the chamber and the field.

  8. The responses of Petunia to simulated pollutants in chamber conditions and its uses as bioindicator of pollution

    NASA Astrophysics Data System (ADS)

    Oguntimehin, I. I.; Kondo, H.; Sakugawa, H. H.

    2010-12-01

    Plants damage that results from air pollution are often confused with plant diseases, nutritional deficiency or natural senescence. Bio-indicating plants are used to obtain the direct identification of air pollutants on plants and determine the geographical distribution of pollutants. The responses of two varieties of Petunia (purple and white) to ten treatments including fumigated ozone (‘O’AOT40 28.2 ppm h), 10 µM fluoranthene ‘F’ and H2SO4 (‘A’ pH 3) mist, MQ water sprayed on plants as control ‘C’ with other mixtures were investigated in 30 d under controlled conditions. Also, a 1:1 mixture of Na2S2O3 and 1mM NaOOCCC6H5 form part of the treatments and was used as scavenging solution ‘S’ against Reactive Oxygen Species (ROS). Eco-physiological traits are leaf chlorophyll, carotenoids contents and chlorophyll fluorescence. Metal analysis was by ICP-AES, Histochemical analysis using 3’3-diaminobenzidine (DAB)-HCl, combined with Evans blue staining procedure for hydrogen peroxide deposition and dead cell portion of leaves. Plants health determined as SPAD chlorophyll values at 7, 14, 21 and 28 d of treatments (DOT) were significantly reduced after 28 DOT for the petunia . Chlorophyll depreciation ‘CD’ was > 40% in purple petunia for the ‘O’ containing treatments, < 25% for other treatments and ≈ 10% for ‘C’ whereas it ranged from 25-28% in ‘O’ containing treatments, < 20% for other treatments and 10% for ‘C’. A derivative to assess plant health status by the variation of the ratio (total chlorophyll content: carotenoids) against CD was obtained. Higher R2 value for this derivative in the white petunia suggested that though the leaf of purple petunia indicated higher sensitivity to ozone than the white, white petunia is a better bio-indicator of the stresses examined from the present study. Also, the leaf chlorophyll fluorescence showed higher significant values in the ‘O’ containing and the other treatments in the

  9. RADIATION MONITOR CONTAINING TWO CONCENTRIC IONIZATION CHAMBERS AND MEANS FOR INSULATING THE SEPARATE CHAMBERS

    DOEpatents

    Braestrup, C.B.; Mooney, R.T.

    1964-01-21

    This invention relates to a portable radiation monitor containing two concentric ionization chambers which permit the use of standard charging and reading devices. It is particularly adapted as a personnel x-ray dosimeter and to this end comprises a small thin walled, cylindrical conductor forming an inner energy dependent chamber, a small thin walled, cylindrical conductor forming an outer energy independent chamber, and polymeric insulation means which insulates said chambers from each other and holds the chambers together with exposed connections in a simple, trouble-free, and compact assembly substantially without variation in directional response. (AEC)

  10. CONTINUOUS ROTATION SCATTERING CHAMBER

    DOEpatents

    Verba, J.W.; Hawrylak, R.A.

    1963-08-01

    An evacuated scattering chamber for use in observing nuclear reaction products produced therein over a wide range of scattering angles from an incoming horizontal beam that bombards a target in the chamber is described. A helically moving member that couples the chamber to a detector permits a rapid and broad change of observation angles without breaching the vacuum in the chamber. Also, small inlet and outlet openings are provided whose size remains substantially constant. (auth)

  11. Construction of a fast ionization chamber for high-rate particle identification

    NASA Astrophysics Data System (ADS)

    Chae, K. Y.; Ahn, S.; Bardayan, D. W.; Chipps, K. A.; Manning, B.; Pain, S. D.; Peters, W. A.; Schmitt, K. T.; Smith, M. S.; Strauss, S. Y.

    2014-07-01

    A new gas-filled ionization chamber for high count rate particle identification has been constructed and commissioned at the Holifield Radioactive Ion Beam Facility (HRIBF) at Oak Ridge National Laboratory (ORNL). To enhance the response time of the ionization chamber, a design utilizing a tilted entrance window and tilted electrodes was adopted, which is modified from an original design by Kimura et al. [1]. A maximum counting rate of 700 , 000 particles per second has been achieved. The detector has been used for several radioactive beam measurements performed at the HRIBF.

  12. Two chamber reaction furnace

    DOEpatents

    Blaugher, Richard D.

    1998-05-05

    A vertical two chamber reaction furnace. The furnace comprises a lower chamber having an independently operable first heating means for heating the lower chamber and a gas inlet means for admitting a gas to create an ambient atmosphere, and an upper chamber disposed above the lower chamber and having an independently operable second heating means for heating the upper chamber. Disposed between the lower chamber and the upper chamber is a vapor permeable diffusion partition. The upper chamber has a conveyor means for conveying a reactant there through. Of particular importance is the thallinating of long-length thallium-barium-calcium-copper oxide (TBCCO) or barium-calcium-copper oxide (BCCO) precursor tapes or wires conveyed through the upper chamber to thereby effectuate the deposition of vaporized thallium (being so vaporized as the first reactant in the lower chamber at a temperature between about 700.degree. and 800.degree. C.) on TBCCO or BCCO tape or wire (the second reactant) at its simultaneous annealing temperature in the upper chamber of about 800.degree. to 950.degree. C. to thereby replace thallium oxide lost from TBCCO tape or wire because of the high annealing temperature or to deposit thallium on BCCO tape or wire. Continuously moving the tape or wire provides a single-step process that effectuates production of long-length TBCCO superconducting product.

  13. Two chamber reaction furnace

    DOEpatents

    Blaugher, R.D.

    1998-05-05

    A vertical two chamber reaction furnace is described. The furnace comprises a lower chamber having an independently operable first heating means for heating the lower chamber and a gas inlet means for admitting a gas to create an ambient atmosphere, and an upper chamber disposed above the lower chamber and having an independently operable second heating means for heating the upper chamber. Disposed between the lower chamber and the upper chamber is a vapor permeable diffusion partition. The upper chamber has a conveyor means for conveying a reactant there through. Of particular importance is the thallinating of long-length thallium-barium-calcium-copper oxide (TBCCO) or barium-calcium-copper oxide (BCCO) precursor tapes or wires conveyed through the upper chamber to thereby effectuate the deposition of vaporized thallium (being so vaporized as the first reactant in the lower chamber at a temperature between about 700 C and 800 C) on TBCCO or BCCO tape or wire (the second reactant) at its simultaneous annealing temperature in the upper chamber of about 800 to 950 C to thereby replace thallium oxide lost from TBCCO tape or wire because of the high annealing temperature or to deposit thallium on BCCO tape or wire. Continuously moving the tape or wire provides a single-step process that effectuates production of long-length TBCCO superconducting product. 2 figs.

  14. Dual chamber rate responsive pacing system driven by contractility: final assessment after 1-year follow-up. The European PEA Clinical Investigation Group.

    PubMed

    Clémenty, J

    1998-11-01

    The aim of this study was to assess the long-term performance of a new dual chamber rate responsive pacing system based on the dynamic measurement of the peak endocardial acceleration (PEA) index of cardiac contractility. Seventy patients who participated in the Multicenter European Clinical Evaluation were studied 1 year after implantation by continuously recording the PEA and the heart rate (HR) during exercise stress testing and during 24 hours of usual activities. A complete examination of standard parameters was also performed to assess the pacing/sensing lead characteristics. Statistical comparisons were performed with the data recorded with the same protocol at 1 month after implant for each patient. A linear correlation coefficient was calculated between PEA and sinus rate when the patient showed predominant atrial tracked rhythm. There were no significant differences between PEA values measured at 1 month and 1 year (PEA = 0.41 +/- 0.26 g vs 0.45 +/- 0.29 g at rest and PEA = 1.63 +/- 0.77 g vs 1.72 +/- 0.83 g during peak exercise). The correlation coefficient remained stable (0.67 +/- 0.15 vs 0.65 +/- 0.14 during daily life and 0.74 +/- 0.14 vs 0.77 +/- 0.11 during exercise). The PEA signal detected by the sensor was reliable and stable. No long-term complications or adverse effects were observed, and the lead performance was comparable to that of a standard lead.

  15. Mesocosm Community Response Sensitivities to Specific Conductivity Comprised of Different Major Ions

    EPA Science Inventory

    Traditional toxicity test assays have been used to evaluate the relative sensitivity to different major ion mixtures as a proxy for understanding what the response of aquatic species growing in their natural environment would be during exposure to specific conductivity stress ema...

  16. Stream mesocosm response sensitivities to simulated ion stress in produced waters from resource extraction activities

    EPA Science Inventory

    To increase the ecological relevance of laboratory exposures intent on determining species sensitivity to ion stress from resource extraction activities we have conducted several stream mesocosm dosing studies that pair single-species and community-level responses in-situ and all...

  17. SU-D-19A-01: Can Farmer-Type Ionization Chambers Be Used to Improve the Accuracy of Low-Energy Electron Beam Reference Dosimetry?

    SciTech Connect

    Muir, B R; McEwen, M R

    2014-06-01

    Purpose: To investigate the use of cylindrical Farmer-type ionization chambers to improve the accuracy of low-energy electron beam calibration. Historically, these chamber types have not been used in beams with incident energies less than 10 MeV (R{sub 5} {sub 0} < 4.3 cm) because early investigations suggested large (up to 5 %) fluence perturbation factors in these beams, implying that a significant component of uncertainty would be introduced if used for calibration. More recently, the assumptions used to determine perturbation corrections for cylindrical chambers have been questioned. Methods: Measurements are made with cylindrical chambers in Elekta Precise 4, 8 and 18 MeV electron beams. Several chamber types are investigated that employ graphite walls and aluminum electrodes with very similar specifications (NE2571, NE2505/3, FC65-G). Depth-ionization scans are measured in water in the 8 and 18 MeV beams. To reduce uncertainty from chamber positioning, measurements in the 4 MeV beam are made at the reference depth in Virtual Water™. The variability of perturbation factors is quantified by comparing normalized response of various chambers. Results: Normalized ion chamber response varies by less than 0.7 % for similar chambers at average electron energies corresponding to that at the reference depth from 4 or 6 MeV beams. Similarly, normalized measurements made with similar chambers at the reference depth in the 4 MeV beam vary by less than 0.4 %. Absorbed dose calibration coefficients derived from these results are stable within 0.1 % on average over a period of 6 years. Conclusion: These results indicate that the uncertainty associated with differences in fluence perturbations for cylindrical chambers with similar specifications is only 0.2 %. The excellent long-term stability of these chambers in both photon and electron beams suggests that these chambers might offer the best performance for all reference dosimetry applications.

  18. The effect of a compression paddle on energy response, calibration and measurement with mammographic dosimeters using ionization chambers and solid-state detectors.

    PubMed

    Hourdakis, C J; Boziari, A; Koumbouli, E

    2009-02-21

    A compression paddle is always used in mammography x-ray examinations, in order to improve image quality and reduce patient doses. Although clinical dose measurements should be performed with the paddle to interfere with the x-ray beam, calibration of mammography dosimeters is performed free in air without the presence of the paddle. The paddle hardens the x-ray beam, which has an impact on a dosimeter performance, particularly on high-energy-dependent detectors. Due to the paddle, clinical mammography x-ray systems may exhibit beams with HVL values exceeding those of the IEC 61267 RQR-M series qualities at which dosimeters are usually calibrated. In this study, the influence of the paddle in mammography dosimetry is examined, in Mo/Mo anode/filter x-ray qualities. PMMA slabs of 1, 2 and 3 mm thickness and Al foils of 0.05, 0.10 and 0.15 mm thicknesses were used to simulate the paddles, producing beams with HVL values from 0.28 up to 0.43 mmAl. In these qualities, four solid-state (ST) detectors and three ionizations chambers (IC) were calibrated in terms of Kair and N(K) and k(Q) were deduced. The results showed that all IC and two modern-type ST dosimeters have a flat energy response in the above HVL range (less than 3%), so their calibration factor at RQR-M2 quality could be safely used for clinical measurements. Two other ST dosimeters exhibit up to 20% energy response, so differences up to 15% in dose measurement may be observed if the effect of paddle on their performance is ignored. Finally, the need of additional mammographic calibration qualities to the existing IEC 61267 RQR-M series is examined and discussed.

  19. Neutron Detection via Bubble Chambers

    SciTech Connect

    Jordan, David V.; Ely, James H.; Peurrung, Anthony J.; Bond, Leonard J.; Collar, J. I.; Flake, Matthew; Knopf, Michael A.; Pitts, W. K.; Shaver, Mark W.; Sonnenschein, Andrew; Smart, John E.; Todd, Lindsay C.

    2005-10-06

    The results of a Pacific Northwest National Laboratory (PNNL) exploratory research project investigating the feasibility of fast neutron detection using a suitably prepared and operated, pressure-cycled bubble chamber are described. The research was conducted along two parallel paths. Experiments with a slow pressure-release Halon chamber at the Enrico Fermi Institute at the University of Chicago showed clear bubble nucleation sensitivity to an AmBe neutron source and insensitivity to the 662 keV gammas from a 137Cs source. Bubble formation was documented via high-speed (1000 frames/sec) photography, and the acoustic signature of bubble formation was detected using a piezo-electric transducer element mounted on the base of the chamber. The chamber’s neutron sensitivity as a function of working fluid temperature was mapped out. The second research path consisted of the design, fabrication, and testing of a fast pressure-release Freon-134a chamber at PNNL. The project concluded with successful demonstrations of the PNNL chamber’s AmBe neutron source sensitivity and 137Cs gamma insensitivity. The source response tests of the PNNL chamber were documented with high-speed photography.

  20. Subcellular Spatial Correlation of Particle Traversal and Biological Response in Clinical Ion Beams

    SciTech Connect

    Niklas, Martin; Abdollahi, Amir; Akselrod, Mark S.; Debus, Jürgen; Jäkel, Oliver; and others

    2013-12-01

    Purpose: To report on the spatial correlation of physical track information (fluorescent nuclear track detectors, FNTDs) and cellular DNA damage response by using a novel hybrid detector (Cell-Fit-HD). Methods and Materials: The FNTDs were coated with a monolayer of human non-small cell lung carcinoma (A549) cells and irradiated with carbon ions (270.55 MeV u{sup −1}, rising flank of the Bragg peak). Phosphorylated histone variant H2AX accumulating at the irradiation-induced double-strand break site was labeled (RIF). The position and direction of ion tracks in the FNTD were registered with the location of the RIF sequence as an ion track surrogate in the cell layer. Results: All RIF sequences could be related to their corresponding ion tracks, with mean deviations of 1.09 μm and −1.72 μm in position and of 2.38° in slope. The mean perpendicular between ion track and RIF sequence was 1.58 μm. The mean spacing of neighboring RIFs exhibited a regular rather than random spacing. Conclusions: Cell-Fit-HD allows for unambiguous spatial correlation studies of cell damage with respect to the intracellular ion traversal under therapeutic beam conditions.

  1. ION-1 technical manual

    SciTech Connect

    Halbig, J.K.; Caine, J.C.

    1985-07-01

    The portable gamma-ray and neutron detector electronics (ION-1) gives a digital readout of the current-mode response produced by gamma rays in an ion chamber and of amplification and scaling of pulses received from a neutron detector. The primary application is the measurement of gamma-ray and neutron activity of irradiated reactor fuels stored at a reactor or at a storage pond away from a reactor. ION-1 is the first such instrument to use a design that allows communication of procedures, response, and results between instrument and inspector. It prompts the inspector through procedures, carries out programmed measurement steps, calculates results and error estimates, and performs internal diagnostic checks. This Technical Manual describes adjustment procedures and limited technical information that enable the inspector to troubleshoot at the board level. 5 figs., 10 tabs.

  2. Detection of Large Ions in Time-of-Flight Mass Spectrometry: Effects of Ion Mass and Acceleration Voltage on Microchannel Plate Detector Response

    NASA Astrophysics Data System (ADS)

    Liu, Ranran; Li, Qiyao; Smith, Lloyd M.

    2014-08-01

    In time-of-flight mass spectrometry (TOF-MS), ion detection is typically accomplished by the generation and amplification of secondary electrons produced by ions colliding with a microchannel plate (MCP) detector. Here, the response of an MCP detector as a function of ion mass and acceleration voltage is characterized, for singly charged peptide/protein ions ranging from 1 to 290 kDa in mass, and for acceleration voltages from 5 to 25 kV. A nondestructive inductive charge detector (ICD) employed in parallel with MCP detection provides a reliable reference signal to allow accurate calibration of the MCP response. MCP detection efficiencies were very close to unity for smaller ions at high acceleration voltages (e.g., angiotensin, 1046.5 Da, at 25 kV acceleration voltage), but decreased to ~11% for the largest ions examined (immunoglobulin G (IgG) dimer, 290 kDa) even at the highest acceleration voltage employed (25 kV). The secondary electron yield γ (average number of electrons produced per ion collision) is found to be proportional to mv3.1 (m: ion mass, v: ion velocity) over the entire mass range examined, and inversely proportional to the square root of m in TOF-MS analysis. The results indicate that although MCP detectors indeed offer superlative performance in the detection of smaller peptide/protein species, their performance does fall off substantially for larger proteins, particularly under conditions of low acceleration voltage.

  3. Detection of large ions in time-of-flight mass spectrometry: effects of ion mass and acceleration voltage on microchannel plate detector response.

    PubMed

    Liu, Ranran; Li, Qiyao; Smith, Lloyd M

    2014-08-01

    In time-of-flight mass spectrometry (TOF-MS), ion detection is typically accomplished by the generation and amplification of secondary electrons produced by ions colliding with a microchannel plate (MCP) detector. Here, the response of an MCP detector as a function of ion mass and acceleration voltage is characterized, for singly charged peptide/protein ions ranging from 1 to 290 kDa in mass, and for acceleration voltages from 5 to 25 kV. A nondestructive inductive charge detector (ICD) employed in parallel with MCP detection provides a reliable reference signal to allow accurate calibration of the MCP response. MCP detection efficiencies were very close to unity for smaller ions at high acceleration voltages (e.g., angiotensin, 1046.5 Da, at 25 kV acceleration voltage), but decreased to ~11% for the largest ions examined (immunoglobulin G (IgG) dimer, 290 kDa) even at the highest acceleration voltage employed (25 kV). The secondary electron yield γ (average number of electrons produced per ion collision) is found to be proportional to mv(3.1) (m: ion mass, v: ion velocity) over the entire mass range examined, and inversely proportional to the square root of m in TOF-MS analysis. The results indicate that although MCP detectors indeed offer superlative performance in the detection of smaller peptide/protein species, their performance does fall off substantially for larger proteins, particularly under conditions of low acceleration voltage.

  4. ION SOURCE

    DOEpatents

    Leland, W.T.

    1960-01-01

    The ion source described essentially eliminater the problem of deposits of nonconducting materials forming on parts of the ion source by certain corrosive gases. This problem is met by removing both filament and trap from the ion chamber, spacing them apart and outside the chamber end walls, placing a focusing cylinder about the filament tip to form a thin collimated electron stream, aligning the cylinder, slits in the walls, and trap so that the electron stream does not bombard any part in the source, and heating the trap, which is bombarded by electrons, to a temperature hotter than that in the ion chamber, so that the tendency to build up a deposit caused by electron bombardment is offset by the extra heating supplied only to the trap.

  5. Influence of nonionic surfactants on the potentiometric response of hydrogen ion-selective polymeric membrane electrodes.

    PubMed

    Espadas-Torre, C; Bakker, E; Barker, S; Meyerhoff, M E

    1996-05-01

    The influence of poly(ethylene oxide)-based nonionic surfactants (i.e., Triton X-100 and Brij 35) in the sample phase on the response properties of hydrogen ion-selective polymeric membrane electrodes containing mobile (lipophilic amines) or covalently bound (aminated-poly-(vinyl chloride)) hydrogen ion carriers is reported. In the presence of these nonionic surfactants, membrane electrode response toward interfering cation activity (e.g., Na+) in the sample phase is increased substantially and the pH measuring range shortened. The degree of cation interference for pH measurements is shown to correlate with the basicity of the hydrogen ion carrier doped within the membrane phase. The observed deterioration in selectivity arises from the partitioning of the surfactant into the membrane and concomitant extraction of metal cations by the surfactants in the organic phase. The effect of nonionic surfactants on pH electrodes prepared with aminated-PVC membranes is shown to be more complex, with additional large shifts in EMF values apparently arising from multidentate interactions between the surfactant molecules and the polymeric amine in the membrane, leading to a change in the apparent pKa values for the amine sites. The effects induced by nonionic surfactants on the EMF response function of hydrogen ion-selective polymeric membrane electrodes are modeled, and experimental results are shown to correlate well with theoretical predictions.

  6. Quantised transistor response to ion channels revealed by nonstationary noise analysis

    NASA Astrophysics Data System (ADS)

    Becker-Freyseng, C.; Fromherz, P.

    2011-11-01

    We report on the quantised response of a field-effect transistor to molecular ion channels in a biomembrane. HEK293-type cells overexpressing the Shaker B potassium channel were cultured on a silicon chip. An enhanced noise of the transistor is observed when the ion channels are activated. The analysis of the fluctuations in terms of binomial statistics identifies voltage quanta of about 1 μV on the gate. They are attributed to the channel currents that affect the gate voltage according to the Green's function of the cell-chip junction.

  7. Dual mode ion mobility spectrometer and method for ion mobility spectrometry

    DOEpatents

    Scott, Jill R [Idaho Falls, ID; Dahl, David A [Idaho Falls, ID; Miller, Carla J [Idaho Falls, ID; Tremblay, Paul L [Idaho Falls, ID; McJunkin, Timothy R [Idaho Falls, ID

    2007-08-21

    Ion mobility spectrometer apparatus may include an ion interface that is operable to hold positive and negative ions and to simultaneously release positive and negative ions through respective positive and negative ion ports. A first drift chamber is operatively associated with the positive ion port of the ion interface and encloses an electric field therein. A first ion detector operatively associated with the first drift chamber detects positive ions from the first drift chamber. A second drift chamber is operatively associated with the negative ion port of the ion interface and encloses an electric field therein. A second ion detector operatively associated with the second drift chamber detects negative ions from said second drift chamber.

  8. [Open-top Chamber for in situ Research on Response of Mercury Enrichment in Rice to the Rising Gaseous Elemental Mercury in the Atmosphere].

    PubMed

    Chen, Jian; Wang, Zhang-wei; Zhang, Xiao-shan; Qin, Pu-feng; Lu, Hai-jun

    2015-08-01

    In situ research was conducted on the response of mercury enrichment in rice organs to elevated gaseous elemental mercury (GEM) with open-top chambers (OTCs) fumigation experiment and soil Hg enriched experiment. The results showed that Hg concentrations in roots were generally correlated with soil Hg concentrations (R = 0.9988, P < 0.05) but insignificantly correlated with air Hg concentrations (P > 0.05), indicating that Hg in rice roots was mainly from soil. Hg concentrations in stems increased linearly (R(B) = 0.9646, R(U) = 0.9831, P < 0.05) with elevated GEM, and Hg concentrations in upper stems were usually higher than those in bottom stems in OTCs experiment. Hg concentrations in bottom stems were generally correlated with soil Hg concentrations (R = 0.9901, P < 0.05) and second-order polynomial (R = 0.9989, P < 0.05) was fitted for Hg concentrations in upper stems to soil Hg concentrations, and Hg concentrations in bottom stems were usually higher than those in upper stems in soil Hg enriched experiment, indicating the combining impact of Hg from air and soil on the accumulation of mercury in stems. Hg concentrations in foliage were significantly correlated (P < 0.05) with air Hg and linearly correlated with soil Hg (R = 0.9983, P = 0.0585), implying that mercury in foliage was mainly from air and some of Hg in root from soil was transferred to foliage through stem. Based on the function in these filed experiments, it was estimated that at least 60%-94% and 56%-77% of mercury in foliage and upper-stem of rice was from the atmosphere respectively, and yet only 8%-56% of mercury in bottom-stem was attributed to air. Therefore, mercury in rice aboveground biomass was mainly from the atmosphere, and these results will provide theoretical basis for the regional atmospheric mercury budgets and the model of mercury cycling.

  9. SU-E-T-156: Can Sr-90 Check Sources Replace Co-60 Measurements for Monitoring of Reference Chamber Stability?

    SciTech Connect

    McEwen, M; Niven, D; Miksys, N

    2015-06-15

    Purpose: To determine the ultimate precision of a system for monitoring reference-class ion chamber stability using a commercial Sr-90 check source. Methods: A detailed investigation of a commercial Sr-90 check source (PTW48002) was carried out using a series of Farmer-type ionization chambers. Investigations included: positioning repeatability (angular variation as chamber is rotated in source, variation in ionization current with vertical alignment); chamber settling; short and long term repeatability Results: i) Measurement precision – the ionization current was typically 10 pA, and therefore a high-precision electrometer is required to prevent electrometer noise/resolution/leakage biaising the results. ii) Chamber settling - the chamber response stabilizes after approximately 10 minutes, which is longer than reported for linac beams and is likely due to the low doserate of the source.iii) The measured response depended at the 1 % level on the orientation of the chamber with respect to the source. However, consistent positioning resulted in repeatability at the 0.05 % level. Care was also required to ensure that the chamber was consistently positioned vertically with respect to the source. The sensitivity to vertical position was found to be > 1 % per mm.iv)With a uniform procedure the long-term (> 6 month) repeatability was found to be better than 0.1 % for multiple chamber types and potentially a precision of 0.05 % is achievable. Conclusion: A Sr-90 check source is easy to use and is a viable alternative to Co-60 for monitoring reference chamber stability.

  10. Morphological and biochemical responses of Oryza sativa L. (cultivar MR219) to ion beam irradiation*

    PubMed Central

    Ling, Anna Pick Kiong; Ung, Ying Chian; Hussein, Sobri; Harun, Abdul Rahim; Tanaka, Atsushi; Yoshihiro, Hase

    2013-01-01

    Objective: Heavy ion beam, which has emerged as a new mutagen in the mutation breeding of crops and ornamental plants, is expected to result in the induction of novel mutations. This study investigates the morphological and biochemical responses of Oryza sativa toward different doses of carbon ion beam irradiation. Methods: In this study, the dry seeds of O. sativa were irradiated at 0, 20, 40, 60, 80, 100, and 120 Gy, followed by in-vitro germination under controlled conditions. Morphological and biochemical studies were conducted to investigate the morphological and physiological responses of O. sativa towards ion beam irradiation. Results: The study demonstrated that low doses (10 Gy) of ion beam have a stimulating effect on the height, root length, and fresh weight of the plantlets but not on the number of leaves. Meanwhile, doses higher than 10 Gy caused reductions in all the morphological parameters studied as compared to the control samples. The highest total soluble protein content [(2.11±0.47) mg/g FW] was observed in plantlets irradiated at 20 Gy. All irradiated plantlets were found to have 0.85% to 58.32% higher specific activity of peroxidase as compared to the control samples. The present study also revealed that low doses of ion beam (10 and 20 Gy) had negligible effect on the total chlorophyll content of O. sativa plantlets while 40 Gy had a stimulating effect on the chlorophyll content. Plantlets irradiated between 40 to 120 Gy were shown to be 0.38% to 9.98% higher in total soluble nitrogen content which, however, was not significantly different from the control samples. Conclusions: Carbon ion beam irradiation administered at low to moderate doses of 10 to 40 Gy may induce O. sativa mutants with superior characteristics. PMID:24302713

  11. Fibroblast Response to Lanthanoid Metal Ion Stimulation: Potential Contribution to Fibrotic Tissue Injury

    PubMed Central

    Jenkins, William; Perone, Patricia; Walker, Kyle; Bhagavathula, Narasimharao; Aslam, Muhammad Nadeem; DaSilva, Marissa; Dame, Michael K.; Varani, James

    2011-01-01

    The purpose of this study was to compare each of the 14 naturally occurring lanthanoid metal ions for ability to stimulate pro-fibrotic responses in human dermal fibroblasts. When fibroblasts were exposed to individual lanthanoids over the concentration range of 1–100 μM, increased proliferation was observed with each of the agents as compared with control cells that were already proliferating rapidly in a growth factor-enriched culture medium. Dose-response differences were observed among the individual metal ions. Matrix metalloproteinase-1 (MMP-1) and tissue inhibitor of metalloproteinase-1 levels were also increased in response to lanthanoid exposure but type I procollagen production was not. A dose–response relationship between induction of proliferation and increased MMP-1 was observed. Non-lanthanoid transition metal ions (aluminum, copper, cobalt, iron, magnesium, manganese, nickel, and zinc) were examined in the same assays; there was little stimulation with any of these metals. When epidermal keratinocytes were examined in place of dermal fibroblasts, there was no growth stimulation with any of the lanthanoids. Several of the lanthanoid metals inhibited keratinocyte proliferation at higher concentrations (50–100 μM). PMID:21484406

  12. Inorganic backbone ionomers: Design and dielectric response of single-ion conducting polymers

    NASA Astrophysics Data System (ADS)

    Bartels, Joshua

    analysis of the static dielectric constant and show excellent agreement with x-ray scattering and DFT calculations, each ionomer strongly favoring the formation of quadrupoles. Finally a polysiloxane ionomer was considered and was mixed with three anion and/or cation solvating additives, tetraglyme, tetraethylene glycol, and branched poly(ethylenimine). The EP model of the dielectric response gives the conducting ion concentration and the mobility of conducting ions and shows an increase in conducting ion concentration with both anion solvating and cation solvating additives. The static dielectric constant indicates an increased preference for ion pairs when anion receptors are present. Most interestingly, the additive that best decreased the glass transition temperature and increased the static dielectric constant did not result in the best dc conductivity. The best dc conductivity resulted from tetraglyme because it solvated cations without interacting with the polymer. High ion conductivities have not been observed in polymer systems that decouple charge transport from polymer motion, and therefore low Tg ionomers are the natural path forward for commercially viable ionomers. Inorganic backbone polymers impart a low Tg without bringing any strong disadvantage to ionomers. These materials are very important for developing superior ion conductors and should be pursued in future ionomer research.

  13. Growth, Yield, and Nutritional Responses of Chamber-Grown Sweet Potato to Elevated Carbon Dioxide Levels Expected Across the Next 200 Years

    NASA Astrophysics Data System (ADS)

    Czeck, B. C.; Jahren, H.; Deenik, J. L.; Crow, S. E.; Schubert, B.; Stewart, M.

    2012-12-01

    Understanding the effects of increasing atmospheric carbon dioxide (CO2) concentrations on crops will be critical to assuring that sufficient food is available to the world's growing population. Previous work has shown that slightly elevated CO2 levels (CO2 = 550-700 ppm) increase the economic yield of most crops by ~33%, on average. The majority of these studies have focused on rice, wheat, and soybean; however, climate change is expected to have greatest impact on regions of the world that rely heavily on root crops, such as sweet potato (Ipomoea batatas). Sweet potato is cultivated in more than 100 developing countries; it is ranked seventh in world crop statistics and can produce more edible energy per hectare and per day than wheat, rice or cassava. In order to quantify the effect that rising CO2 levels will have on sweet potato, we grew a total of 64 sweet potato plants to maturity in large controlled growth chambers at ambient, 760, 1,140, and 1,520-ppm CO2 levels. At planting, initial measurements (of mass, length, and number of nodes) for each plant were recorded. Throughout the duration of the experiment (90 days) measurements (of stem length, and number of leaves) were recorded every 7 to 14 days. To ensure optimum growing conditions moisture content was monitored using soil tensiometers; temperature, relative humidity and CO2 concentrations were recorded every ten minutes. Half the plants were supplemented with an inorganic fertilizer and the other half with an organic fertilizer to test the effect of nutrient availability on biomass production under elevated CO2 levels. After 3 months of growth, we measured fresh and dry biomass of all above- and below-ground tissues. Results showed a substantial increase in both above- and below-ground biomass at elevated levels of CO2. For the organic treatment, a 43% increase in aboveground dry biomass at the highest CO2 concentration (1520ppm) was found; the inorganic treatment showed a 31% increase. The

  14. Media ion composition controls regulatory and virulence response of Salmonella in spaceflight.

    PubMed

    Wilson, James W; Ott, C Mark; Quick, Laura; Davis, Richard; Höner zu Bentrup, Kerstin; Crabbé, Aurélie; Richter, Emily; Sarker, Shameema; Barrila, Jennifer; Porwollik, Steffen; Cheng, Pui; McClelland, Michael; Tsaprailis, George; Radabaugh, Timothy; Hunt, Andrea; Shah, Miti; Nelman-Gonzalez, Mayra; Hing, Steve; Parra, Macarena; Dumars, Paula; Norwood, Kelly; Bober, Ramona; Devich, Jennifer; Ruggles, Ashleigh; CdeBaca, Autumn; Narayan, Satro; Benjamin, Joseph; Goulart, Carla; Rupert, Mark; Catella, Luke; Schurr, Michael J; Buchanan, Kent; Morici, Lisa; McCracken, James; Porter, Marc D; Pierson, Duane L; Smith, Scott M; Mergeay, Max; Leys, Natalie; Stefanyshyn-Piper, Heidemarie M; Gorie, Dominic; Nickerson, Cheryl A

    2008-01-01

    The spaceflight environment is relevant to conditions encountered by pathogens during the course of infection and induces novel changes in microbial pathogenesis not observed using conventional methods. It is unclear how microbial cells sense spaceflight-associated changes to their growth environment and orchestrate corresponding changes in molecular and physiological phenotypes relevant to the infection process. Here we report that spaceflight-induced increases in Salmonella virulence are regulated by media ion composition, and that phosphate ion is sufficient to alter related pathogenesis responses in a spaceflight analogue model. Using whole genome microarray and proteomic analyses from two independent Space Shuttle missions, we identified evolutionarily conserved molecular pathways in Salmonella that respond to spaceflight under all media compositions tested. Identification of conserved regulatory paradigms opens new avenues to control microbial responses during the infection process and holds promise to provide an improved understanding of human health and disease on Earth.

  15. High accuracy position response calibration method for a micro-channel plate ion detector

    NASA Astrophysics Data System (ADS)

    Hong, R.; Leredde, A.; Bagdasarova, Y.; Fléchard, X.; García, A.; Müller, P.; Knecht, A.; Liénard, E.; Kossin, M.; Sternberg, M. G.; Swanson, H. E.; Zumwalt, D. W.

    2016-11-01

    We have developed a position response calibration method for a micro-channel plate (MCP) detector with a delay-line anode position readout scheme. Using an in situ calibration mask, an accuracy of 8 μm and a resolution of 85 μm (FWHM) have been achieved for MeV-scale α particles and ions with energies of ∼10 keV. At this level of accuracy, the difference between the MCP position responses to high-energy α particles and low-energy ions is significant. The improved performance of the MCP detector can find applications in many fields of AMO and nuclear physics. In our case, it helps reducing systematic uncertainties in a high-precision nuclear β-decay experiment.

  16. The effects of depth-dependent crustal viscosity variation on visco-elastic response to inflation/deflation of magma chamber

    NASA Astrophysics Data System (ADS)

    Yamasaki, Tadashi

    2016-04-01

    Development of the satellite observations (GPS and/or InSAR) has allowed us to precisely measure surface deformation. However any geodetic observation by itself does not tell us a mechanism of the deformation. All we can do the most is to compare such an observation to some quantitative predictions, only from which we can deduce a possible deformation mechanism. We therefore need to understand characteristic deformation pattern for a given source mechanism. This study particularly pays attention to magmatic activity in depth as the source, aiming to distinguish magma-induced crustal deformation by better knowing how the activity can be reflected in geodetically observable surface deformation. A parallelized 3-D finite element code, OREGANO_VE [e.g., Yamasaki and Houseman, 2015, J. Geodyn., 88, 80-89], is used to solve the linear Maxwell visco-elastic response to an applied internal inflation/deflation of magma chamber. The rectangular finite element model is composed with a visco-elastic layer overlaid by an elastic layer with thickness of H, and the visco-elastic layer extends over the rest of crust and the uppermost mantle. The visco-elastic crust has a depth-dependent viscosity (DDV) as an exponential function of depth due to temperature-dependent viscosity: hc = h0 exp[c(1 - z/L0)], where h0 is the viscosity at the bottom of the crust, c is a constant; c > 0 for DDV model and c = 0 for uniform viscosity (UNV) model, z is the depth, and L0 is a reference length-scale. The visco-elastic mantle has a spatially uniform viscosity hm. The inflation and/or deflation of sill-like magma chamber is implemented by using the split node method developed by Melosh and Raefsky [1981, Bull. Seism. Soc. Am., 71, 1391-1400]. UNV model with c = 0 employed in this study shows that the inflation-induced surface uplift would abate with time by visco-elastic relaxation. The post-inflation subsidence would erase the uplift in ~ 50 - 100 times Maxwell relaxation time of the crust

  17. Ion electric propulsion unit

    DOEpatents

    Light, Max E; Colestock, Patrick L

    2014-01-28

    An electron cyclotron resonance (ECR) thruster is disclosed having a plasma chamber which is electrically biased with a positive voltage. The chamber bias serves to efficiently accelerate and expel the positive ions from the chamber. Electrons follow the exiting ions, serving to provide an electrically neutral exhaust plume. In a further embodiment, a downstream shaping magnetic field serves to further accelerate and/or shape the exhaust plume.

  18. The response of the pyrochlore structure-type to ion-beam irradiation

    NASA Astrophysics Data System (ADS)

    Lian, Jie

    Pyrochlore with the general formula of A3+2B4+2O7 (Fd3m; Z = 8) has been proposed as the candidate waste form for the immobilization of actinides, particularly plutonium from dismantled nuclear weapons. Because actinides decay by alpha-decay events, radiation effects on the waste form are a concern. The effects of radiation on different pyrochlore compositions, A2B2O7 (A = La ˜ Lu, and Y; B = Ti, Sn, and Zr), have been investigated by 50 KeV He+, 600 KeV Ar+, 1.0 MeV Kr+, and 1.5 MeV Xe+ ion irradiations. Titanate pyrochlores are generally sensitive to ion beam damage and can be amorphized at a low damage level (˜0.2 dpa). The critical amorphization temperature, Tc, increases from ˜480 to ˜1120 K with increasing A-site cation size. A dramatically increasing radiation "resistance" to ion beam induced-amorphization has been observed with increasing Zr-content in the Gd2Ti2-xZrxO7 system. The pure end-member, Gd2Zr2O7, cannot be amorphized, even at doses as high as ˜100 dpa. Although zirconate pyrochlores are generally considered to be radiation "resistant", ion beam-induced amorphization occurs for La2Zr2O7 at a dose of ˜5.5 dpa at room temperature. Stannate pyrochlores A2Sn 2O7 (A = La, Nd, Gd) are readily amorphized by ion beam damage at a relatively low dose (˜1 dpa) at room temperature; while no evidence of amorphization has been observed in A2Sn2O7 (A = Er, Y, Lu) irradiated with 1 MeV Kr+ ions at a dose of ˜6 dpa at 25 K. The factors that influence the response of different pyrochlore compositions to ion irradiation-induced amorphization are discussed in terms of cation radius ratio, defect formation energies, and the tendency of the pyrochlore structure-type to undergo an order-disorder transition to the defect-fluorite structure. The "resistance" of the pyrochlore structure to ion beam-induced amorphization is not only affected by the relative sizes of the A- and B-site cations, but also the cation electronic configurations. Pyrochlore compositions

  19. Effects of separator breakdown on abuse response of 18650 Li-ion cells

    NASA Astrophysics Data System (ADS)

    Roth, E. P.; Doughty, D. H.; Pile, D. L.

    The thermal abuse tolerance of Li-ion cells depends not only on the stability of the active materials in the anode and cathode but also on the stability of the separator which prevents direct interaction between these electrodes. Separator response has been measured as a function of temperature and high voltage both for isolated materials and in full 18650 cells. Separators with different compositions and properties were measured to determine the effect of separator melt integrity on cell response under abusive conditions. These studies were performed as part of the U.S. Department of Energy (DOE) Advanced Technology Development (ATD) Program.

  20. Note: Small anaerobic chamber for optical spectroscopy

    PubMed Central

    Chauvet, Adrien A. P.; Agarwal, Rachna; Cramer, William A.; Chergui, Majed

    2015-01-01

    The study of oxygen-sensitive biological samples requires an effective control of the atmosphere in which they are housed. In this aim however, no commercial anaerobic chamber is adequate to solely enclose the sample and small enough to fit in a compact spectroscopic system with which analysis can be performed. Furthermore, spectroscopic analysis requires the probe beam to pass through the whole chamber, introducing a requirement for adequate windows. In response to these challenges, we present a 1 l anaerobic chamber that is suitable for broad-band spectroscopic analysis. This chamber has the advantage of (1) providing access, via a septum, to the sample and (2) allows the sample position to be adjusted while keeping the chamber fixed and hermetic during the experiment. PMID:26520998

  1. Note: Small anaerobic chamber for optical spectroscopy

    SciTech Connect

    Chauvet, Adrien A. P. Chergui, Majed; Agarwal, Rachna; Cramer, William A.

    2015-10-15

    The study of oxygen-sensitive biological samples requires an effective control of the atmosphere in which they are housed. In this aim however, no commercial anaerobic chamber is adequate to solely enclose the sample and small enough to fit in a compact spectroscopic system with which analysis can be performed. Furthermore, spectroscopic analysis requires the probe beam to pass through the whole chamber, introducing a requirement for adequate windows. In response to these challenges, we present a 1 l anaerobic chamber that is suitable for broad-band spectroscopic analysis. This chamber has the advantage of (1) providing access, via a septum, to the sample and (2) allows the sample position to be adjusted while keeping the chamber fixed and hermetic during the experiment.

  2. Note: Small anaerobic chamber for optical spectroscopy.

    PubMed

    Chauvet, Adrien A P; Agarwal, Rachna; Cramer, William A; Chergui, Majed

    2015-10-01

    The study of oxygen-sensitive biological samples requires an effective control of the atmosphere in which they are housed. In this aim however, no commercial anaerobic chamber is adequate to solely enclose the sample and small enough to fit in a compact spectroscopic system with which analysis can be performed. Furthermore, spectroscopic analysis requires the probe beam to pass through the whole chamber, introducing a requirement for adequate windows. In response to these challenges, we present a 1 l anaerobic chamber that is suitable for broad-band spectroscopic analysis. This chamber has the advantage of (1) providing access, via a septum, to the sample and (2) allows the sample position to be adjusted while keeping the chamber fixed and hermetic during the experiment.

  3. The Mobile Chamber

    NASA Technical Reports Server (NTRS)

    Scharfstein, Gregory; Cox, Russell

    2012-01-01

    A document discusses a simulation chamber that represents a shift from the thermal-vacuum chamber stereotype. This innovation, currently in development, combines the capabilities of space simulation chambers, the user-friendliness of modern-day electronics, and the modularity of plug-and-play computing. The Mobile Chamber is a customized test chamber that can be deployed with great ease, and is capable of bringing payloads at temperatures down to 20 K, in high vacuum, and with the desired metrology instruments integrated to the systems control. Flexure plans to lease Mobile Chambers, making them affordable for smaller budgets and available to a larger customer base. A key feature of this design will be an Apple iPad-like user interface that allows someone with minimal training to control the environment inside the chamber, and to simulate the required extreme environments. The feedback of thermal, pressure, and other measurements is delivered in a 3D CAD model of the chamber's payload and support hardware. This GUI will provide the user with a better understanding of the payload than any existing thermal-vacuum system.

  4. High resolution drift chambers

    SciTech Connect

    Va'vra, J.

    1985-07-01

    High precision drift chambers capable of achieving less than or equal to 50 ..mu..m resolutions are discussed. In particular, we compare so called cool and hot gases, various charge collection geometries, several timing techniques and we also discuss some systematic problems. We also present what we would consider an ''ultimate'' design of the vertex chamber. 50 refs., 36 figs., 6 tabs.

  5. A soundproof pressure chamber.

    PubMed

    Kitahara, M; Kodama, A; Ozawa, H; Inoue, S

    1994-01-01

    For neurotological research we designed a soundproof pressure chamber in which pressure can be adjusted +/- 1000 mmH2O at the rate of less than 100 mmH2O per second. Noise in the chamber can be maintained under 30-35 dB while pressure is kept at a given level.

  6. Static diffusion cloud chambers

    NASA Technical Reports Server (NTRS)

    Ayers, G.

    1981-01-01

    The chamber geometry and optical arrangement are described. The supersaturation range is given and consists of readings taken at five fixed points: 0.25%, 0.5%, 0.75%, 1.0%, and 1.25%. The detection system is described including light source, cameras, and photocell detectors. The temperature control and the calibration of the chamber are discussed.

  7. Ion transport mechanisms responsible for K+ secretion and the transepithelial voltage across marginal cells of stria vascularis in vitro.

    PubMed

    Wangemann, P; Liu, J; Marcus, D C

    1995-04-01

    It has long been accepted that marginal cells of stria vascularis are involved in the generation of the endocochlear potential and the secretion of K+. The present study was designed to provide evidence for this hypothesis and for a cell model proposed to explain K+ secretion and the generation of the endocochlear potential. Stria vascularis from the cochlea of the gerbil was isolated and mounted into a micro-Ussing chamber such that the apical and basolateral membrane of marginal cells could be perfused independently. In this preparation, the transepithelial voltage (Vt) and resistance (Rt) were measured across marginal cells and the resulting equivalent short circuit current (Isc) was calculated (Isc = Vt/Rt). Further, K+ secretion (JK+,probe) was measured with a K(+)-selective vibrating probe in the vicinity of the apical membrane. In the absence of extrinsic chemical driving forces, when both sides of the marginal cell epithelium were bathed with a perilymph-like solution, Vt was 8 mV (apical side positive), Rt was 10 ohm-cm2 and Isc was 850 microA/cm2 (N = 27). JK+,probe was outwardly directed from the apical membrane and reversibly inhibited by basolateral bumetanide, a blocker of the Na+/Cl-/K+ cotransporter. On the basolateral but not apical side, oubain and bumetanide each caused a decline of Vt and an increase of Rt suggesting the presence of the Na,K-ATPase and the Na+/Cl-/K+ cotransporter in the basolateral membrane. The responses to [Cl-] steps demonstrated a significant Cl- conductance in the basolateral membrane and a small Cl- conductance in the paracellular pathway or the apical membrane. The responses to [Na+] steps demonstrated no significant Na+ conductance in the basolateral membrane and a small Na+ or nonselective cation conductance in the apical membrane or paracellular pathway. The responses to [K+] steps demonstrated a large K+ conductance in the apical membrane. Apical application of 4,4'-diisothiocyanatostilbene-2,2'-disulfonic acid (DIDS

  8. [Study of the response characteristics of PVC membrane ion-associate type electrodes for organic base cations].

    PubMed

    Kang, X J; Wang, C Y

    1990-01-01

    A new type of ISEs which only uses alkaloid precipitants in place of ion pairs as active materials in polyvinyl chloride was recommended. The characteristics of the electrodes sensing over ten kinds of organic bases have been studied in comparison with those based on ion pairs. It can be concluded that the response characteristics of ion-associate type ISEs depend on the strength of the association between ion-exchange site and principal ions. Visual turbidimetry was used to select active materials for ISEs in advance. Among six alkaloid precipitants (silicotungstic acid, tetraphenyl borate, dipicrylamine, picric acid, picrolonic acid and Reineckate), silicotungstic acid is the most active material for ion-associate type organic base cation ISEs. With it, the sensor has wider Nernst linearity and lower detection limit than some ion pair based ones in literature.

  9. Effects of CO2 enrichment and drought pretreatment on metabolite responses to water stress and subsequent rehydration using potato tubers from plants grown in sunlit SPAR chambers

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Experiments were performed using naturally sunlit Soil–Plant–Atmosphere-Research chambers that provided ambient or elevated CO2. Potato plants were grown in pots that were water sufficient (W), water insufficient for 12 to 18 days during both vegetative and tuber development stages (VR), or water i...

  10. Altered ion-responsive gene expression in Mmp20 null mice.

    PubMed

    Tye, C E; Sharma, R; Smith, C E; Bartlett, J D

    2010-12-01

    During enamel maturation, hydroxyapatite crystallites expand in volume, releasing protons that acidify the developing enamel. This acidity is neutralized by the buffering activity of carbonic anhydrases and ion transporters. Less hydroxyapatite forms in matrix metalloproteinase-20 null (Mmp20(-/-)) mouse incisors, because enamel thickness is reduced by approximately 50%. We therefore asked if ion regulation was altered in Mmp20(-/-) mouse enamel. Staining of wild-type and Mmp20(-/-) incisors with pH indicators demonstrated that wild-type mice had pronounced changes in enamel pH as development progressed. These pH changes were greatly attenuated in Mmp20(-/-) mice. Expression of 4 ion-regulatory genes (Atp2b4, Slc4a2, Car6, Cftr) was significantly decreased in enamel organs from Mmp20(-/-) mice. Notably, expression of secreted carbonic anhydrase (Car6) was reduced to almost undetectable levels in the null enamel organ. In contrast, Odam and Klk4 expression was unaffected. We concluded that a feedback mechanism regulates ion-responsive gene expression during enamel development.

  11. Physical response of gold nanoparticles to single self-ion bombardment

    DOE PAGES

    Bufford, Daniel C.; Hattar, Khalid

    2014-09-23

    The reliability of nanomaterials depends on maintaining their specific sizes and structures. However, the stability of many nanomaterials in radiation environments remains uncertain due to the lack of a fully developed fundamental understanding of the radiation response on the nanoscale. To provide an insight into the dynamic aspects of single ion effects in nanomaterials, gold nanoparticles (NPs) with nominal diameters of 5, 20, and 60 nm were subjected to self-ion irradiation at energies of 46 keV, 2.8 MeV, and 10 MeV in situ inside of a transmission electron microscope. Ion interactions created a variety of far-from-equilibrium structures including small (~1more » nm) sputtered nanoclusters from the parent NPs of all sizes. Single ions created surface bumps and elongated nanofilaments in the 60 nm NPs. As a result, similar shape changes were observed in the 20 nm nanoparticles, while the 5 nm nanoparticles were transiently melted or explosively broken apart.« less

  12. Physical response of gold nanoparticles to single self-ion bombardment

    SciTech Connect

    Bufford, Daniel C.; Hattar, Khalid

    2014-09-23

    The reliability of nanomaterials depends on maintaining their specific sizes and structures. However, the stability of many nanomaterials in radiation environments remains uncertain due to the lack of a fully developed fundamental understanding of the radiation response on the nanoscale. To provide an insight into the dynamic aspects of single ion effects in nanomaterials, gold nanoparticles (NPs) with nominal diameters of 5, 20, and 60 nm were subjected to self-ion irradiation at energies of 46 keV, 2.8 MeV, and 10 MeV in situ inside of a transmission electron microscope. Ion interactions created a variety of far-from-equilibrium structures including small (~1 nm) sputtered nanoclusters from the parent NPs of all sizes. Single ions created surface bumps and elongated nanofilaments in the 60 nm NPs. As a result, similar shape changes were observed in the 20 nm nanoparticles, while the 5 nm nanoparticles were transiently melted or explosively broken apart.

  13. The Light Response of the XENON100 Time Projection Chamber and the Measurements of the Optical Parameters with the Xenon Scintillation Light

    NASA Astrophysics Data System (ADS)

    Choi, Bin

    The XENON program is a phased project using liquid xenon as a sensitive detector medium in search for weakly interacting massive particles (WIMPs). These particles are the leading candidates to explain the non-baryonic, cold dark matter in our Universe. XENON100, the successor experiment of XENON10, has increased the target liquid xenon mass to 61 kg with a 100 times reduction in background rate enabling a large increase in sensitivity to WIMP-nucleon interaction cross-section. To-date, the most stringent limit on this cross-section over a wide range of WIMP masses have been obtained with XENON100. XENON100 is a detector responding to the scintillation of xenon and the work of this thesis will mainly focus on the light response of the detector. Chapter 1 describes the evidences for dark matter and some of the detection methods, roughly divided by the indirect and the direct detection. In the section 1.2.2 for direct detection, a treatment of interaction rate of WIMPs is introduced. Chapter 2 is a description of the XENON100 detector, some of the main characteristics of liquid xenon, followed by the detector design. In Chapter 3, the light response of the XENON100 time projection chamber (TPC) is explained, including the Monte Carlo simulation work that was carried out prior to the main data taking. The Monte Carlo provided the basic idea of understanding the detector in the early stage of design and calibration, but the actual corrections of the light signals were determined later with the real data. Several optical parameters are critical in explaining the light response, such as the quantum efficiency (QE) of the photomultipliers (PMTs) used in the detector and the reflectivity of the teflon (Polytetrafluoroethylene, PTFE) material that surrounds the liquid xenon target volume and defines the TPC. Since the few existing measurements of reflectivity of PTFE in liquid xenon were performed in different conditions and thus could not be applied, the XENON

  14. Biphasic responses of human vascular smooth muscle cells to magnesium ion

    PubMed Central

    Ma, Jun; Zhao, Nan; Zhu, Donghui

    2016-01-01

    Magnesium-based alloys are promising in biodegradable cardiovascular stent applications. The degradation products of magnesium stents may have significant impacts on the surrounding vascular cells. However, knowledge on the interactions between magnesium ion and vascular cells at the molecular and cellular levels is still largely missing. Vascular smooth muscle cell (SMC) plays an important role in the pathogenesis of restenosis and wound healing after stent implantation. This study evaluated the short-term effects of extracellular magnesium ion (Mg2+) on the cellular behaviors of SMCs. Cellular responses to Mg2+ were biphasic and in a concentration-dependent manner. Low concentrations (10 mM) of Mg2+ increased cell viability, cell proliferation rate, cell adhesion, cell spreading, cell migration rate, and actin expression. In contrast, higher concentrations (40–60 mM) of Mg2+ had deleterious effects on cells. Gene expression analysis revealed that Mg2+ altered the expressions of genes mostly related to cell adhesion, cell injury, angiogenesis, inflammation, coagulation, and cell growth. Finding from this study provides some valuable information on SMC responses toward magnesium ions at the cellular and molecular levels, and guidance for future controlled release of magnesium from the stent material. PMID:26402437

  15. Biphasic responses of human vascular smooth muscle cells to magnesium ion.

    PubMed

    Ma, Jun; Zhao, Nan; Zhu, Donghui

    2016-02-01

    Magnesium-based alloys are promising in biodegradable cardiovascular stent applications. The degradation products of magnesium stents may have significant impacts on the surrounding vascular cells. However, knowledge on the interactions between magnesium ion and vascular cells at the molecular and cellular levels is still largely missing. Vascular smooth muscle cell (SMC) plays an important role in the pathogenesis of restenosis and wound healing after stent implantation. This study evaluated the short-term effects of extracellular magnesium ion (Mg(2+)) on the cellular behaviors of SMCs. Cellular responses to Mg(2+) were biphasic and in a concentration-dependent manner. Low concentrations (10 mM) of Mg(2+) increased cell viability, cell proliferation rate, cell adhesion, cell spreading, cell migration rate, and actin expression. In contrast, higher concentrations (40-60 mM) of Mg(2+) had deleterious effects on cells. Gene expression analysis revealed that Mg(2+) altered the expressions of genes mostly related to cell adhesion, cell injury, angiogenesis, inflammation, coagulation, and cell growth. Finding from this study provides some valuable information on SMC responses toward magnesium ions at the cellular and molecular levels, and guidance for future controlled release of magnesium from the stent material.

  16. The response of tissue-equivalent proportional counters to heavy ions

    NASA Technical Reports Server (NTRS)

    Nikjoo, Hooshang; Khvostunov, Igor K.; Cucinotta, Francis A.

    2002-01-01

    The paper presents a theoretical model for the response of a tissue-equivalent proportional counter (TEPC) irradiated with charged particles. Heavy ions and iron ions in particular constitute a significant part of radiation in space. TEPCs are used for all space shuttle and International Space Station (ISS) missions to estimate the dose and radiation quality (in terms of lineal energy) inside spacecraft. The response of the tissue-equivalent proportional counters shows distortions at the wall/cavity interface. In this paper, we present microdosimetric investigation using Monte Carlo track structure calculations to simulate the response of a TEPC to charged particles of various LET (1 MeV protons, 2.4 MeV alpha particles, 46 MeV/nucleon 20Ne, 55 MeV/nucleon 20Ne, 45 MeV/nucleon 40Ar, and 1.05 GeV/nucleon 56Fe). Data are presented for energy lost and energy absorbed in the counter cavity and wall. The model calculations are in good agreement with the results of Rademacher et al. (Radiat. Res. 149, 387-389, 1998), including the study of the interface between the wall and the sensitive region of the counter. It is shown that the anomalous response observed at large event sizes in the experiment is due to an enhanced entry of secondary electrons from the wall into the gas cavity.

  17. Deciphering the acute cellular phosphoproteome response to irradiation with X-rays, protons and carbon ions.

    PubMed

    Winter, Martin; Dokic, Ivana; Schlegel, Julian; Warnken, Uwe; Debus, Jürgen; Abdollahi, Amir; Schnölzer, Martina

    2017-03-16

    Radiotherapy is a cornerstone of cancer therapy. The recently established particle therapy with raster-scanning protons and carbon ions landmarks a new era in the field of high-precision cancer medicine. However, molecular mechanisms governing radiation induced intracellular signaling remain elusive. Here, we present the first comprehensive proteomic and phosphoproteomic study applying stable isotope labeling by amino acids in cell culture (SILAC) in combination with high-resolution mass spectrometry to decipher cellular response to irradiation with X-rays, protons and carbon ions. At protein expression level limited alterations were observed 2h post irradiation of human lung adenocarcinoma cells. In contrast, 181 phosphorylation sites were found to be differentially regulated out of which 151 sites were not hitherto attributed to radiation response as revealed by crosscheck with the PhosphoSitePlus database. Radiation-induced phosphorylation of the p(S/T)Q motif was the prevailing regulation pattern affecting proteins involved in DNA damage response signaling. Since radiation doses were selected to produce same level of cell kill and DNA double-strand breakage for each radiation quality, DNA damage responsive phosphorylation sites were regulated to same extent. However, differential phosphorylation between radiation qualities was observed for 55 phosphorylation sites indicating the existence of distinct signaling circuitries induced by X-ray versus particle (proton/carbon) irradiation beyond the canonical DNA damage response. This unexpected finding was confirmed in targeted spike-in experiments using synthetic isotope labeled phosphopeptides. Herewith, we successfully validated uniform DNA damage response signaling coexisting with altered signaling involved in apoptosis and metabolic processes induced by X-ray and particle based treatments. In summary, the comprehensive insight into the radiation-induced phosphoproteome landscape is instructive for the design of

  18. Radiation damage to tetramethylsilane and tetramethylgermanium ionization chambers

    SciTech Connect

    Hoshi, Y.; Higuchi, M.; Oyama, K. . Dept. of Applied Physics)

    1994-08-01

    Two detector media suitable for a warm liquid, ionization chamber filled with tetramethylsilane (TMS) and tetramethylgermanium (TMG) were exposed to [gamma] radiation form a [sup 60]Co source up to dose 579 Gray and 902 Gray, respectively. The electron lifetimes and the free ion yields were measured as a function of accumulated radiation dose. A similar behavior of the electron lifetimes and the free ion yields with increasing radiation does was observed between the TMS and TMG ionization chambers.

  19. Abrupt onset of tongue deformation and phase space response of ions in magnetically-confined plasmas

    PubMed Central

    Ida, K.; Kobayashi, T.; Itoh, K.; Yoshinuma, M.; Tokuzawa, T.; Akiyama, T.; Moon, C.; Tsuchiya, H.; Inagaki, S.; Itoh, S.-I.

    2016-01-01

    An abrupt onset of the new tongue-shaped deformation of magnetic surface in magnetized plasmas, which was conjectured in since the 1960s but has not been observed, is experimentally identified just before an abrupt onset of a large-scale collapse event. Two novel properties of the event are identified. First, the transition of symmetry of perturbation (rather than a growth of linearly unstable MHD modes) was found to be a key for the onset of abrupt collapse, i.e., the transition of symmetry gives a new route to the collapse from stable state. Second, as a phase-space response of ions, the distortion from Maxwell-Boltzmann distribution of epithermal ions was observed for the first time. PMID:27796370

  20. Abrupt onset of tongue deformation and phase space response of ions in magnetically-confined plasmas

    NASA Astrophysics Data System (ADS)

    Ida, K.; Kobayashi, T.; Itoh, K.; Yoshinuma, M.; Tokuzawa, T.; Akiyama, T.; Moon, C.; Tsuchiya, H.; Inagaki, S.; Itoh, S.-I.

    2016-10-01

    An abrupt onset of the new tongue-shaped deformation of magnetic surface in magnetized plasmas, which was conjectured in since the 1960s but has not been observed, is experimentally identified just before an abrupt onset of a large-scale collapse event. Two novel properties of the event are identified. First, the transition of symmetry of perturbation (rather than a growth of linearly unstable MHD modes) was found to be a key for the onset of abrupt collapse, i.e., the transition of symmetry gives a new route to the collapse from stable state. Second, as a phase-space response of ions, the distortion from Maxwell-Boltzmann distribution of epithermal ions was observed for the first time.

  1. The Japanese Radon and Thoron Reference Chambers

    SciTech Connect

    Tokonami, Shinji; Ishikawa, Tetsuo; Sorimachi, Atsuyuki; Takahashi, Hiroyuki; Miyahara, Nobuyuki

    2008-08-07

    Passive detectors used for large-scale and long-term surveys are generally calibrated in a well-controlled environment such as a radon chamber. It has been also pointed out that some of them are sensitive to thoron. Thus it is necessary to check the thoron contribution to the detector response with the proposed or similar test before practical use. The NIRS accommodates radon/aerosol and thoron chambers for quality assurance and quality control of radon measurements. Thus both chambers work so well that they can supply us with the calibration technique and consequently, a good level of knowledge of the radon and thoron issue.

  2. Ion beam generating apparatus

    DOEpatents

    Brown, Ian G.; Galvin, James

    1987-01-01

    An ion generating apparatus utilizing a vacuum chamber, a cathode and an anode in the chamber. A source of electrical power produces an arc or discharge between the cathode and anode. The arc is sufficient to vaporize a portion of the cathode to form a plasma. The plasma is directed to an extractor which separates the electrons from the plasma, and accelerates the ions to produce an ion beam.

  3. The Mars Chamber

    NASA Video Gallery

    The Mars chamber is a box about the size of a refrigerator that re-creates the temperatures, pressures, and atmosphere of the Martian surface, essentially creating a Mars environment on Earth! Scie...

  4. Studies on the application of temperature-responsive ion exchange polymers with whey proteins.

    PubMed

    Maharjan, Pankaj; Campi, Eva M; De Silva, Kirthi; Woonton, Brad W; Jackson, W Roy; Hearn, Milton T W

    2016-03-18

    Several new types of temperature-responsive ion exchange resins of different polymer composition have been prepared by grafting the products from the co-polymerisation of N-phenylacrylamide, N-iso-propylacrylamide and acrylic acid derivatives onto cross-linked agarose. Analysis of the binding isotherms for these different resins obtained under batch adsorption conditions indicated that the resin based on N-iso-propylacrylamide containing 5% (w/w) N-phenylacrylamide and 5% (w/w) acrylic acid resulted in the highest adsorption capacity, Bmax, for the whey protein, bovine lactoferrin, e.g. 14 mg bovine lactoferrin/mL resin at 4 °C and 62 mg bovine lactoferrin/mL resin at 40 °C, respectively. Under dynamic loading conditions at 40 °C, 94% of the loaded bovine lactoferrin on a normalised mg protein per mL resin basis was adsorbed by this new temperature-responsive ion-exchanger, and 76% was eluted by a single cycle temperature shift to 4 °C without varying the composition of the 10mM sodium dihydrogen phosphate buffer, pH 6.5, or the flow rate. The binding characteristics of these different ion exchange resins with bovine lactoferrin were also compared to results obtained using other resins based on N-isopropylacrylamide but contained N-tert-butylacrylamide rather than N-phenylacrylamide, where the corresponding dynamic capture and release properties for bovine lactoferrin required different temperature conditions of 20 °C and 50 °C, respectively for optimal desorption/adsorption. The cationic protein, bovine lactoperoxidase, was also adsorbed and desorbed with these temperature-responsive resins under similar conditions of changing temperature, whereas the anionic protein, bovine β-lactoglobulin, was not adsorbed under this regime of temperature conditions but instead eluted in the flow-through.

  5. Sleeve reaction chamber system

    DOEpatents

    Northrup, M. Allen; Beeman, Barton V.; Benett, William J.; Hadley, Dean R.; Landre, Phoebe; Lehew, Stacy L.; Krulevitch, Peter A.

    2009-08-25

    A chemical reaction chamber system that combines devices such as doped polysilicon for heating, bulk silicon for convective cooling, and thermoelectric (TE) coolers to augment the heating and cooling rates of the reaction chamber or chambers. In addition the system includes non-silicon-based reaction chambers such as any high thermal conductivity material used in combination with a thermoelectric cooling mechanism (i.e., Peltier device). The heat contained in the thermally conductive part of the system can be used/reused to heat the device, thereby conserving energy and expediting the heating/cooling rates. The system combines a micromachined silicon reaction chamber, for example, with an additional module/device for augmented heating/cooling using the Peltier effect. This additional module is particularly useful in extreme environments (very hot or extremely cold) where augmented heating/cooling would be useful to speed up the thermal cycling rates. The chemical reaction chamber system has various applications for synthesis or processing of organic, inorganic, or biochemical reactions, including the polymerase chain reaction (PCR) and/or other DNA reactions, such as the ligase chain reaction.

  6. Infrared responsivity enhancement for silicon detectors by non-mask reactive ion etching

    NASA Astrophysics Data System (ADS)

    Liao, Naiman; Kou, Linlai; Luo, Chunlin; Li, Renhao

    2016-10-01

    Near Infrared responsivity of silicon-based detectors is low for weak light absorption in the wavelengths exceeding 1000nm. For 1064nm wavelength applications, it is necessary to use thick Si wafers to manufacturing devices for higher NIR responsivity performance. However, this leads to high applied voltage, long response time, imposing limitations on device characteristics and applications. Black silicon (BS) appears very high absorptance of light from the near-ultraviolet (250nm) to the near-infrared (2500nm) wavelength region. And the black silicon detectors are many times more responsivity than conventional silicon detectors in the near infrared. In this article, BS is prepared using non-mask reactive ion etching technique and PIN BS detectors are fabricated. It is indicated that there is a disordered layer that is 2.0μm -3.5μm thick and made up of pillars with 90nm-400nm in diameter and 200nm-600nm in spacing interval. The reflectance of BS is less than 7% in the wavelength from 400nm to 1100nm, and rises from 1040nm. The absorptance of BS sample prepared by non-mask reactive ion etching remains more than 93% from 400nm to 1040nm, and the absorptance of 60% is observed at the wavelengths longer than 1500nm. High temperature annealing does not deteriorate its light absorption performance. The front-illuminated and back-illuminated BS PIN detectors are structured. At the wavelength of 1064nm, the responsivities of front-illuminated and back-illuminated BS PIN detectors are improved from 0.30A/W to 0.43A/W and 0.58A/W respectively.

  7. Thin-film silica sol-gels doped with ion-responsive fluorescent lipid bilayers

    NASA Astrophysics Data System (ADS)

    Sasaki, Darryl Y.; Shea, Lauren E.; Sinclair, Michael B.

    1999-05-01

    A metal ion sensitive, fluorescent lipid-bilayer material (5% PSIDA/DSPC) was successfully immobilized in a silica matrix using a tetramethoxysilane (TMOS) sol-gel procedure. The sol- gel immobilization method was quantitative in the entrapment of self-assembled lipid-bilayers and yielded thin films for facile configuration to optical fiber platforms. The silica matrix was compatible with the solvent sensitive lipid bilayers and provided physical stabilization as well as biological protection. Immobilization in the silica sol-gel produced an added benefit of improving the bilayer's metal ion sensitivity by up to two orders of magnitude. This enhanced performance was attributed to a preconcentrator effect from the anionic surface of the silica matrix. Thin gels (193 micron thickness) were coupled to a bifurcated fiber optic bundle to produce a metal ion sensor probe. Response times of 10 - 15 minutes to 0.1 M CuCl2 were realized with complete regeneration of the sensor using an ethylenediaminetetraacetic acid (EDTA) solution.

  8. Thin-film silica sol-gels doped with ion responsive fluorescent lipid bilayers

    SciTech Connect

    Sasaki, D.Y.; Shea, L.E.; Sinclair, M.B.

    1999-01-12

    A metal ion sensitive, fluorescent lipid-b i layer material (5oA PSIDA/DSPC) was successfully immobilized in a silica matrix using a tetramethoxysilane (TMOS) sol-gel procedure. The sol-gel immobilization method was quantitative in the entrapment of seif-assembled Iipid-bilayers and yielded thin films for facile configuration to optical fiber piatforms. The silica matrix was compatible with the solvent sensitive lipid bilayers and provided physical stabilization as well as biological protection. Immobilization in the silica sol-gel produced an added benefit of improving the bilayer's metal ion sensitivity by up to two orders of magnitude. This enhanced performance was attributed to a preconcentrator effect from the anionic surface of the silica matrix. Thin gels (193 micron thickness) were coupled to a bifurcated fiber optic bundle to produce a metal ion sensor probe. Response times of 10 - 15 minutes to 0.1 M CUCIZ were realized with complete regeneration of the sensor using an ethylenediarninetetraacetic acid (EDTA) solution.

  9. Synergistic effect of nanotopography and bioactive ions on peri-implant bone response

    PubMed Central

    Su, Yingmin; Komasa, Satoshi; Li, Peiqi; Nishizaki, Mariko; Chen, Luyuan; Terada, Chisato; Yoshimine, Shigeki; Nishizaki, Hiroshi; Okazaki, Joji

    2017-01-01

    Both bioactive ion chemistry and nanoscale surface modifications are beneficial for enhanced osseointegration of endosseous implants. In this study, a facile synthesis approach to the incorporation of bioactive Ca2+ ions into the interlayers of nanoporous structures (Ca-nano) formed on a Ti6Al4V alloy surface was developed by sequential chemical and heat treatments. Samples with a machined surface and an Na+ ion-incorporated nanoporous surface (Na-nano) fabricated by concentrated alkali and heat treatment were used in parallel for comparison. The bone response was investigated by microcomputed tomography assessment, sequential fluorescent labeling analysis, and histological and histomorphometric evaluation after 8 weeks of implantation in rat femurs. No significant differences were found in the nanotopography, surface roughness, or crystalline properties of the Ca-nano and Na-nano surfaces. Bone–implant contact was better in the Ca-nano and Na-nano implants than in the machined implant. The Ca-nano implant was superior to the Na-nano implant in terms of enhancing the volume of new bone formation. The bone formation activity consistently increased for the Ca-nano implant but ceased for the Na-nano implant in the late healing stage. These results suggest that Ca-nano implants have promising potential for application in dentistry and orthopedics. PMID:28184162

  10. Discharge Chamber Primary Electron Modeling Activities in Three-Dimensions

    NASA Technical Reports Server (NTRS)

    Steuber, Thomas J.

    2004-01-01

    Designing discharge chambers for ion thrusters involves many geometric configuration decisions. Various decisions will impact discharge chamber performance with respect to propellant utilization efficiency, ion production costs, and grid lifetime. These hardware design decisions can benefit from the assistance of computational modeling. Computational modeling for discharge chambers has been limited to two-dimensional codes that leveraged symmetry for interpretation into three-dimensional analysis. This paper presents model development activities towards a three-dimensional discharge chamber simulation to aid discharge chamber design decisions. Specifically, of the many geometric configuration decisions toward attainment of a worthy discharge chamber, this paper focuses on addressing magnetic circuit considerations with a three-dimensional discharge chamber simulation as a tool. With this tool, candidate discharge chamber magnetic circuit designs can be analyzed computationally to gain insight into factors that may influence discharge chamber performance such as: primary electron loss width in magnetic cusps, cathode tip position with respect to the low magnetic field volume, definition of a low magnetic field region, and maintenance of a low magnetic field region across the grid span. Corroborating experimental data will be obtained from mockup hardware tests. Initially, simulated candidate magnetic circuit designs will resemble previous successful thruster designs. To provide opportunity to improve beyond previous performance benchmarks, off-design modifications will be simulated and experimentally tested.

  11. The NF-kB pathway: LET dependence of the biological response to heavy ion beams

    NASA Astrophysics Data System (ADS)

    Hellweg, Christine; Baumstark-Khan, Christa; Arenz, Andrea; Reitz, Guenther; Schmitz, Claudia; Spitta, Luis F.; Ruscher, Roland; Lau, Patrick; Meier, Matthias M.; Testard, Isabelle

    Radiation is an acknowledged primary concern for manned spaceflight and is a potentially limiting factor for long term orbital and interplanetary missions. A solar flare can threaten the astronauts' life, and long-term exposure to galactic cosmic rays may shorten the healthy life-span after return to Earth due to cancer induction. Understanding of the cellular and molecular processes underlying these phenomena may allow better risk estimation and development of appropriate countermeasures. A central factor in the cellular stress response is the transcription factor nuclear factor κB (NF-κB). As an antiapoptotic factor, if activated in human cells by ion beam exposure, it could influence the cancer risk of astronauts exposed to cosmic radiation and improve cellular survival after exposure to high radiation doses. In previous studies using a screening assay for the detection of NF-κB-dependent gene induction (HEK-pNF-κB-d2EGFP/Neo cells), the activation of this transcription factor by heavy ions was shown (Radiat. Res. 164: 527-530, 2005). In this work, the dependency of NF-κB activation on LET was examined. Accelerated argon ions (36 Ar, 95 MeV/u, LET 232 keV/` ım) activate the NF-κB pathway already at low particle densities (1-2 particle hits per nucleus), which result in as less as 5-50 induced double strand breaks per cell. Accelerated carbon ions (13 C, 75 MeV/u, LET 30 keV/µm) induce NF-κB-dependent gene expression at higher particle densities (50-500 particle hits per nucleus), but to a lower extent than the argon ions. Intermediate NF-κB activation is initiated by exposure of human cells with carbon ions with an LET of 70 keV/µm. Sparsely ionizing radiation such as X-rays activates the NF-κB pathway at high doses (> 4 Gy), neutrons at doses > 3 Gy. These results suggest a LET dependency of NF-κB activation: high LET radiation activates NF-κB - dependent on initial nuclear DNA damage followed by cytoplasmic signalling events - more efficiently

  12. Examination of the Ion Beam Response of III-V Semiconductor Substrates

    NASA Astrophysics Data System (ADS)

    Grossklaus, Kevin A.

    This work examines the response of the III-V materials to ion beam irradiation in a series of four experimental studies and describes the observed results in terms of the fundamental materials processes and properties that control ion-induced change in those compounds. Two studies investigate the use of Ga+ focused ion beam (FIB) irradiation of III-V substrate materials to create nanostructures. In the first, the creation of FIB induced group III nanodots on GaAs, InP, InAs, and AlAs is studied. The analysis of those results in terms of basic material properties and a simple nanodot growth model represents the first unified investigation of the fundamental processes that drive the nanodot forming behavior of the III-V compounds. The second nanostructure formation study reports the discovery and characterization of unique spike-like InAs nanostructures, termed "nanospikes," which may be useful for nanoscale electronic or thermoelectric applications. A novel method for controlling nanospike formation using InAs/InP heterostructures and film pre-patterning is developed, and the electrical properties of these ion erosion created nanostructures are characterized by in-situ TEM nanoprobe testing in a first-of-its-kind examination. The two remaining studies examine methods for using ion beam modification of III-V substrates to accommodate lattice-mismatched film growth with improved film properties. The first examines the effects of film growth on a wide range of different FIB created 3-D substrate patterns, and finds that 3-D surface features and patterns significantly alter film morphology and that growth on or near FIB irradiated regions does not improve film threading defect density. The second substrate modification study examines broad beam ion pre-implantation of GaAs wafers before InGaAs film growth, and is the first reported study of III-V substrate pre-implantation. Ar + pre-implantation was found to enhance the formation of threading defects in InGaAs films and

  13. Ectoenzyme activity in coastal marine waters: response to temperature and metal ion availability

    NASA Astrophysics Data System (ADS)

    Wiedenbeck, J. K.; Neino, V.; Allison, S. D.; Martiny, A.

    2009-12-01

    Ectoenzymes in the ocean are vital for the breakdown of complex organic substrates and for the uptake of nutrients by marine organisms. The activity levels of these enzymes affect the turnover rate of nutrient pools within the ocean, and thus have a significant impact on global biogeochemical nutrient cycles. This study measured the activity of extracellular enzymes from seawater samples under different environmental conditions. Samples were collected daily from coastal waters in the subtropical North Pacific (Lat.: 33°). Ambient seawater temperatures were between 18° and 20° C for the duration of the study. The activity response of four enzymes (alkaline phosphatase, β-glucosidase, β-N-acetyl glucosaminidase, and leucine aminopeptidase) was measured over a range of temperatures (4° to 40° C). The optimal temperatures of all four enzymes were above the ambient seawater temperature of the samples: optimal temperatures of β-glucosidase, β-N-acetyl glucosaminidase, and leucine aminopeptidase in the seawater samples were between 28° and 34° C, while alkaline phosphatase activity increased with the temperature over the range tested. Enzymatic activity of alkaline phosphatase was further investigated under several metal ion conditions. Activity was highest in the presence of Co2+ ions, while the availability of other ions (Ca2+ and Mg2+/Zn2+) had a lesser effect. The influence of Co2+ on alkaline phosphatase activity indicates the presence of a Co2+-dependent alkaline phosphatase in coastal marine waters. These results suggest that variations in environmental conditions (such as temperature and ion concentration) have discernable effects on enzyme activity, and thus affect turnover rates of nutrient pools in the ocean.

  14. Exchangeable Ions Are Responsible for the In Vitro Antibacterial Properties of Natural Clay Mixtures

    PubMed Central

    Otto, Caitlin C.; Haydel, Shelley E.

    2013-01-01

    We have identified a natural clay mixture that exhibits in vitro antibacterial activity against a broad spectrum of bacterial pathogens. We collected four samples from the same source and demonstrated through antibacterial susceptibility testing that these clay mixtures have markedly different antibacterial activity against Escherichia coli and methicillin-resistant Staphylococcus aureus (MRSA). Here, we used X-ray diffraction (XRD) and inductively coupled plasma – optical emission spectroscopy (ICP-OES) and – mass spectrometry (ICP-MS) to characterize the mineralogical and chemical features of the four clay mixture samples. XRD analyses of the clay mixtures revealed minor mineralogical differences between the four samples. However, ICP analyses demonstrated that the concentrations of many elements, Fe, Co, Cu, Ni, and Zn, in particular, vary greatly across the four clay mixture leachates. Supplementation of a non-antibacterial leachate containing lower concentrations of Fe, Co, Ni, Cu, and Zn to final ion concentrations and a pH equivalent to that of the antibacterial leachate generated antibacterial activity against E. coli and MRSA, confirming the role of these ions in the antibacterial clay mixture leachates. Speciation modeling revealed increased concentrations of soluble Cu2+ and Fe2+ in the antibacterial leachates, compared to the non-antibacterial leachates, suggesting these ionic species specifically are modulating the antibacterial activity of the leachates. Finally, linear regression analyses comparing the log10 reduction in bacterial viability to the concentration of individual ion species revealed positive correlations with Zn2+ and Cu2+ and antibacterial activity, a negative correlation with Fe3+, and no correlation with pH. Together, these analyses further indicate that the ion concentration of specific species (Fe2+, Cu2+, and Zn2+) are responsible for antibacterial activity and that killing activity is not solely attributed to pH. PMID:23691149

  15. The LIFE Dynamic Chamber System

    NASA Astrophysics Data System (ADS)

    Rhodes, Mark; Kane, Jave; Latkowski, Jeffery; Cook, Andrew; Divol, Laurent; Loosmore, Gwendolen; Scott, Howard; Scullard, Christian; Tabak, Max; Wilks, Scott; Moses, Gregory; Heltemes, Thad; Sacks, Ryan; Pantano, Carlos; Kramer, Richard

    2011-10-01

    Dry-wall IFE designs such as LIFE utilize Xe fill gas to protect the target chamber first wall from x-ray heating and ionic debris. A key question is how cool, settled and clean the Xe must be to permit beam propagation and target transport, and how to reach this state at a 10+ Hz shot repetition rate. Xe is at low density in the target chamber, and purified Xe is reinjected at higher density and lower temperature into the larger outer chamber. Maintenance of this density difference due to blast waves generated by implosion of the target capsules is being assessed with HYDRA and 3D VTF, and possible validation experiments are being investigated. Detailed gas response near the wall is being studied using 3D Miranda. A laboratory-scale theta pinch experiment will study cooling and beam propagation in Xe. This work performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under Contract DE-AC52-07NA27344.

  16. Chamber B Thermal/Vacuum Chamber: User Test Planning Guide

    NASA Technical Reports Server (NTRS)

    Montz, Mike E.

    2012-01-01

    Test process, milestones and inputs are unknowns to first-time users of Chamber B. The User Test Planning Guide aids in establishing expectations for both NASA and non-NASA facility customers. The potential audience for this guide includes both internal and commercial spaceflight hardware/software developers. It is intended to assist their test engineering personnel in test planning and execution. Material covered includes a roadmap of the test process, roles and responsibilities of facility and user, major milestones, facility capabilities, and inputs required by the facility. Samples of deliverables, test article interfaces, and inputs necessary to define test scope, cost, and schedule are included as an appendix to the guide.

  17. Sputtering erosion in ion and plasma thrusters

    NASA Technical Reports Server (NTRS)

    Ray, Pradosh K.

    1995-01-01

    An experimental set-up to measure low-energy (below 1 keV) sputtering of materials is described. The materials to be bombarded represent ion thruster components as well as insulators used in the stationary plasma thruster. The sputtering takes place in a 9 inch diameter spherical vacuum chamber. Ions of argon, krypton and xenon are used to bombard the target materials. The sputtered neutral atoms are detected by a secondary neutral mass spectrometer (SNMS). Samples of copper, nickel, aluminum, silver and molybdenum are being sputtered initially to calibrate the spectrometer. The base pressure of the chamber is approximately 2 x 10(exp -9) Torr. the primary ion beam is generated by an ion gun which is capable of delivering ion currents in the range of 20 to 500 nA. The ion beam can be focused to a size approximately 1 mm in diameter. The mass spectrometer is positioned 10 mm from the target and at 90 deg angle to the primary ion beam direction. The ion beam impinges on the target at 45 deg. For sputtering of insulators, charge neutralization is performed by flooding the sample with electrons generated from an electron gun. Preliminary sputtering results, methods of calculating the instrument response function of the spectrometer and the relative sensitivity factors of the sputtered elements will be discussed.

  18. Non-Targeted Effects and the Dose Response for Heavy Ion Tumorigenesis

    NASA Technical Reports Server (NTRS)

    Chappelli, Lori J.; Cucinotta, Francis A.

    2010-01-01

    BACKGROUND: There is no human epidemiology data available to estimate the heavy ion cancer risks experienced by astronauts in space. Studies of tumor induction in mice are a necessary step to estimate risks to astronauts. Previous experimental data can be better utilized to model dose response for heavy ion tumorigenesis and plan future low dose studies. DOSE RESPONSE MODELS: The Harderian Gland data of Alpen et al.[1-3] was re-analyzed [4] using non-linear least square regression. The data set measured the induction of Harderian gland tumors in mice by high-energy protons, helium, neon, iron, niobium and lanthanum with LET s ranging from 0.4 to 950 keV/micron. We were able to strengthen the individual ion models by combining data for all ions into a model that relates both radiation dose and LET for the ion to tumor prevalence. We compared models based on Targeted Effects (TE) to one motivated by Non-targeted Effects (NTE) that included a bystander term that increased tumor induction at low doses non-linearly. When comparing fitted models to the experimental data, we considered the adjusted R2, the Akaike Information Criteria (AIC), and the Bayesian Information Criteria (BIC) to test for Goodness of fit.In the adjusted R2test, the model with the highest R2values provides a better fit to the available data. In the AIC and BIC tests, the model with the smaller values of the summary value provides the better fit. The non-linear NTE models fit the combined data better than the TE models that are linear at low doses. We evaluated the differences in the relative biological effectiveness (RBE) and found the NTE model provides a higher RBE at low dose compared to the TE model. POWER ANALYSIS: The final NTE model estimates were used to simulate example data to consider the design of new experiments to detect NTE at low dose for validation. Power and sample sizes were calculated for a variety of radiation qualities including some not considered in the Harderian Gland data

  19. Target Chamber Manipulator

    NASA Astrophysics Data System (ADS)

    Tantillo, Anthony; Watson, Matthew

    2015-11-01

    A system has been developed to allow remote actuation of sensors in a high vacuum target chamber used with a particle accelerator. Typically, sensors of various types are placed into the target chamber at specific radial and angular positions relative to the beam line and target. The chamber is then evacuated and the experiments are performed for those sensor positions. Then, the chamber is opened, the sensors are repositioned to new angles or radii, and the process is repeated, with a separate pump-down cycle for each set of sensor positions. The new sensor positioning system allows scientists to pre-set the radii of up to a dozen sensors, and then remotely actuate their angular positions without breaking the vacuum of the target chamber. This reduces the time required to reposition sensors from 6 hours to 1 minute. The sensors are placed into one of two tracks that are separately actuated using vacuum-grade stepping motors. The positions of the sensors are verified using absolute optical rotary encoders, and the positions are accurate to 0.5 degrees. The positions of the sensors are electronically recorded and time-stamped after every change. User control is through a GUI using LabVIEW.

  20. Thrust chamber life prediction

    NASA Technical Reports Server (NTRS)

    Kasper, H. J.

    1985-01-01

    The reusable life of the Space Shuttle main engine (SSME) is influenced by the cyclic life of the regeneratively liquid cooled main combustion chamber (MCC). During an operational duty cycle the MCC liner is subjected to a large transient thermal gradient that imparts a high thermal cyclic strain to the liner hot gas wall. Life predictions of such chambers have usually been based on low cycle fatigue (LCF) evaluations. Hot-fire testing, however, has shown significant mid-channel wall deformation and thinning during accrued cyclic testing. This phenomenon is termed cyclic creep and appears to be significantly accelerated at elevated temperatures. An analytical method that models the cyclic creep phenomenon and its application to thrust chamber life prediction is presented. The chamber finite element geometry is updated periodically to account for accrued wall thinning and distortion. Failure is based on the tensile instability failure criterion. Cyclic life results for several chamber life enhancing coolant channel designs are compared to the typically used LCF analysis that neglects cyclic creep. The results show that the usable cyclic creep life is approximately 30 to 50% of the commonly used LCF life.

  1. Improved Rhenium Thrust Chambers

    NASA Technical Reports Server (NTRS)

    O'Dell, John Scott

    2015-01-01

    Radiation-cooled bipropellant thrust chambers are being considered for ascent/ descent engines and reaction control systems on various NASA missions and spacecraft, such as the Mars Sample Return and Orion Multi-Purpose Crew Vehicle (MPCV). Currently, iridium (Ir)-lined rhenium (Re) combustion chambers are the state of the art for in-space engines. NASA's Advanced Materials Bipropellant Rocket (AMBR) engine, a 150-lbf Ir-Re chamber produced by Plasma Processes and Aerojet Rocketdyne, recently set a hydrazine specific impulse record of 333.5 seconds. To withstand the high loads during terrestrial launch, Re chambers with improved mechanical properties are needed. Recent electrochemical forming (EL-Form"TM") results have shown considerable promise for improving Re's mechanical properties by producing a multilayered deposit composed of a tailored microstructure (i.e., Engineered Re). The Engineered Re processing techniques were optimized, and detailed characterization and mechanical properties tests were performed. The most promising techniques were selected and used to produce an Engineered Re AMBR-sized combustion chamber for testing at Aerojet Rocketdyne.

  2. Selective ion source

    DOEpatents

    Leung, K.N.

    1996-05-14

    A ion source is described wherein selected ions maybe extracted to the exclusion of unwanted ion species of higher ionization potential. Also described is a method of producing selected ions from a compound, such as P{sup +} from PH{sub 3}. The invention comprises a plasma chamber, an electron source, a means for introducing a gas to be ionized by electrons from the electron source, means for limiting electron energy from the electron source to a value between the ionization energy of the selected ion species and the greater ionization energy of an unwanted ion specie, and means for extracting the target ion specie from the plasma chamber. In one embodiment, the electrons are generated in a plasma cathode chamber immediately adjacent to the plasma chamber. A small extractor draws the electrons from the plasma cathode chamber into the relatively positive plasma chamber. The energy of the electrons extracted in this manner is easily controlled. The invention is particularly useful for doping silicon with P{sup +}, As{sup +}, and B{sup +} without the problematic presence of hydrogen, helium, water, or carbon oxide ions. Doped silicon is important for manufacture of semiconductors and semiconductor devices. 6 figs.

  3. Selective ion source

    DOEpatents

    Leung, Ka-Ngo

    1996-01-01

    A ion source is described wherein selected ions maybe extracted to the exclusion of unwanted ion species of higher ionization potential. Also described is a method of producing selected ions from a compound, such as P.sup.+ from PH.sub.3. The invention comprises a plasma chamber, an electron source, a means for introducing a gas to be ionized by electrons from the electron source, means for limiting electron energy from the electron source to a value between the ionization energy of the selected ion species and the greater ionization energy of an unwanted ion specie, and means for extracting the target ion specie from the plasma chamber. In one embodiment, the electrons are generated in a plasma cathode chamber immediately adjacent to the plasma chamber. A small extractor draws the electrons from the plasma cathode chamber into the relatively positive plasma chamber. The energy of the electrons extracted in this manner is easily controlled. The invention is particularly useful for doping silicon with P.sup.+, AS.sup.+, and B.sup.+ without the problematic presence of hydrogen, helium, water, or carbon oxide ions. Doped silicon is important for manufacture of semiconductors and semiconductor devices.

  4. Segmented ion thruster

    NASA Technical Reports Server (NTRS)

    Brophy, John R. (Inventor)

    1993-01-01

    Apparatus and methods for large-area, high-power ion engines comprise dividing a single engine into a combination of smaller discharge chambers (or segments) configured to operate as a single large-area engine. This segmented ion thruster (SIT) approach enables the development of 100-kW class argon ion engines for operation at a specific impulse of 10,000 s. A combination of six 30-cm diameter ion chambers operating as a single engine can process over 100 kW. Such a segmented ion engine can be operated from a single power processor unit.

  5. Automated Electrostatics Environmental Chamber

    NASA Technical Reports Server (NTRS)

    Calle, Carlos; Lewis, Dean C.; Buchanan, Randy K.; Buchanan, Aubri

    2005-01-01

    The Mars Electrostatics Chamber (MEC) is an environmental chamber designed primarily to create atmospheric conditions like those at the surface of Mars to support experiments on electrostatic effects in the Martian environment. The chamber is equipped with a vacuum system, a cryogenic cooling system, an atmospheric-gas replenishing and analysis system, and a computerized control system that can be programmed by the user and that provides both automation and options for manual control. The control system can be set to maintain steady Mars-like conditions or to impose temperature and pressure variations of a Mars diurnal cycle at any given season and latitude. In addition, the MEC can be used in other areas of research because it can create steady or varying atmospheric conditions anywhere within the wide temperature, pressure, and composition ranges between the extremes of Mars-like and Earth-like conditions.

  6. Antipollution combustion chamber

    SciTech Connect

    Caruel, J.E.; Gastebois, P.M.

    1981-01-27

    The invention concerns a combustion chamber for turbojet engines. The combustion chamber is of the annular type and consists of two coaxial flame tubes opening into a common dilution and mixing zone. The inner tube is designed for low operating ratings of the engine, the outer tube for high ratings. Air is injected as far upstream as possible into the dilution zone, to enhance the homogenization of the gaseous flow issuing from the two tubes prior to their passage into the turbine and to assure the optimum radial distribution of temperatures. The combustion chamber according to the invention finds application in a particularly advantageous manner in turbojet engines used in aircraft propulsion because of the reduced emission of pollutants it affords.

  7. Pharmacological Blockade of TRPM8 Ion Channels Alters Cold and Cold Pain Responses in Mice

    PubMed Central

    McCoy, Daniel D.; McKemy, David D.

    2011-01-01

    TRPM8 (Transient Receptor Potential Melastatin-8) is a cold- and menthol-gated ion channel necessary for the detection of cold temperatures in the mammalian peripheral nervous system. Functioning TRPM8 channels are required for behavioral responses to innocuous cool, noxious cold, injury-evoked cold hypersensitivity, cooling-mediated analgesia, and thermoregulation. Because of these various roles, the ability to pharmacologically manipulate TRPM8 function to alter the excitability of cold-sensing neurons may have broad impact clinically. Here we examined a novel compound, PBMC (1-phenylethyl-4-(benzyloxy)-3-methoxybenzyl(2-aminoethyl)carbamate) which robustly and selectively inhibited TRPM8 channels in vitro with sub-nanomolar affinity, as determined by calcium microfluorimetry and electrophysiology. The actions of PBMC were selective for TRPM8, with no functional effects observed for the sensory ion channels TRPV1 and TRPA1. PBMC altered TRPM8 gating by shifting the voltage-dependence of menthol-evoked currents towards positive membrane potentials. When administered systemically to mice, PBMC treatment produced a dose-dependent hypothermia in wildtype animals while TRPM8-knockout mice remained unaffected. This hypothermic response was reduced at lower doses, whereas responses to evaporative cooling were still significantly attenuated. Lastly, systemic PBMC also diminished cold hypersensitivity in inflammatory and nerve-injury pain models, but was ineffective against oxaliplatin-induced neuropathic cold hypersensitivity, despite our findings that TRPM8 is required for the cold-related symptoms of this pathology. Thus PBMC is an attractive compound that serves as a template for the formulation of highly specific and potent TRPM8 antagonists that will have utility both in vitro and in vivo. PMID:21984952

  8. Chamber, Target and Final Focus Integrated Design

    SciTech Connect

    Moir, R.W.

    2000-03-03

    Liquid wall protection, which challenges chamber clearing, has such advantages it's Heavy Ion Fusion's (HIF) main line chamber design. Thin liquid protection from x rays is necessary to avoid erosion of structural surfaces and thick liquid makes structures behind 0.5 m of Flibe (7 mean free paths for 14 MeV neutrons), last the life of the plant. Liquid wall protection holds the promise of greatly increased economic competitiveness. Driver designers require {approx}200 beams to illuminate recent target designs from two sides. The illumination must be compatible with liquid wall protection. The ''best'' values for driver energy, gain, yield and pulse rate comes out of well-known trade-off studies. The chamber design is based on several key assumptions, which are to be proven before HIF can be shown to be feasible. The chamber R&D needed to reduce the unknowns and risks depend on resolving a few technical issues such as jet surface smoothness and rapid chamber clearing.

  9. Filament wound rocket motor chambers

    NASA Technical Reports Server (NTRS)

    1976-01-01

    The design, analysis, fabrication and testing of a Kevlar-49/HBRF-55A filament wound chamber is reported. The chamber was fabricated and successfully tested to 80% of the design burst pressure. Results of the data reduction and analysis from the hydrotest indicate that the chamber design and fabrication techniques used for the chamber were adequate and the chamber should perform adequately in a static test.

  10. Automated soil gas monitoring chamber

    DOEpatents

    Edwards, Nelson T.; Riggs, Jeffery S.

    2003-07-29

    A chamber for trapping soil gases as they evolve from the soil without disturbance to the soil and to the natural microclimate within the chamber has been invented. The chamber opens between measurements and therefore does not alter the metabolic processes that influence soil gas efflux rates. A multiple chamber system provides for repetitive multi-point sampling, undisturbed metabolic soil processes between sampling, and an essentially airtight sampling chamber operating at ambient pressure.

  11. Electrostatic Levitator Vacuum Chamber

    NASA Technical Reports Server (NTRS)

    1998-01-01

    Optical ports ring the Electrostatic Levitator (ESL) vacuum chamber to admit light from the heating laser (beam passes through the window at left), positioning lasers (one port is at center), and lamps to allow diagnostic instruments to view the sample. The ESL uses static electricity to suspend an object (about 2-3 mm in diameter) inside a vacuum chamber while a laser heats the sample until it melts. This lets scientists record a wide range of physical properties without the sample contacting the container or any instruments, conditions that would alter the readings. The Electrostatic Levitator is one of several tools used in NASA's microgravity materials science program.

  12. [Double action potentials in the command neurons of Helix pomatia in response to the action of cobalt ions].

    PubMed

    Palikhova, T A; Khludova, L K; Sokolov, E N

    1987-01-01

    Cobalt chloride (20 mmol/l) in physiological solution results in generation of doublets of spikes in Helix pomatia command neurons in response to intracellularly injected depolarizing current. The extraspikes arise in arborizations of neuron and are determined by influx sodium ions. It is supposed that facilitation of extraspikes in apparently due to long-lasting blockade of calcium-dependent potassium current by Co2+ ions.

  13. Assessing plant response to ambient ozone: growth of young apple trees in open-top chambers and corresponding ambient air plots.

    PubMed

    Manning, W J; Cooley, D R; Tuttle, A F; Frenkel, M A; Bergweiler, C J

    2004-12-01

    Open-top chambers (OTCs) and corresponding ambient air plots (AA) were used to assess the impact of ambient ozone on growth of newly planted apple trees at the Montague Field research center in Amherst, MA. Two-year-old apple trees (Malus domestica Borkh 'Rogers Red McIntosh') were planted in the ground in circular plots. Four of the plots were enclosed with OTCs where incoming air was charcoal-filtered (CF); four were enclosed with OTCs where incoming air was not charcoal-filtered (NF) and four were not enclosed, allowing access to ambient air conditions (AA). Conditions in both CF and NF OTCs resulted in increased tree growth and changed incidence of disease and arthropod pests, compared to trees in AA. As a result, we were not able to use the OTC method to assess the impact of ambient ozone on growth of young apple trees in Amherst, MA.

  14. Response of sensitive human ataxia and resistant T-1 cell lines to accelerated heavy ions

    SciTech Connect

    Tobias, C.A.; Blakely, E.A.; Chang, P.Y.; Lommel, L.; Roots, R.

    1983-07-01

    The radiation dose responses of fibroblast from a patient with Ataxia telangiectasis (AT-2SF) and an established line of human T-1 cells were studied. Nearly monoenergetic accelerated neon and argon ions were used at the Berkeley Bevalac with various residual range values. The LET of the particles varied from 30 keV/..mu..m to over 1000 keV/..mu..m. All Ataxia survival curves were exponential functions of the dose. Their radiosensitivity reached peak values at 100 to 200 keV/..mu..m. Human T-1 cells have effective sublethal damage repair as has been evidenced by split dose experiments, and they are much more resistant to low LET than to high LET radiation. The repair-misrepair model has been used to interpret these results. We have obtained mathematical expressions that describe the cross sections and inactivation coefficients for both human cell lines as a function of the LET and the type of particle used. The results suggest either that high-LET particles induce a greater number of radiolesions per track or that heavy-ions at high LET induce lesions that kill cells more effectively and that are different from those produced at low LET. We assume that the lesions induced in T-1 and Ataxia cells are qualitatively similar and that each cell line attempts to repair these lesions. The result in most irradiated Ataxia cells, however, is either lethal misrepair or incomplete repair leading to cell death. 63 references, 10 figures, 1 table.

  15. Energy loss of ions in a magnetized plasma: conformity between linear response and binary collision treatments.

    PubMed

    Nersisyan, H B; Zwicknagel, G; Toepffer, C

    2003-02-01

    The energy loss of a heavy ion moving in a magnetized electron plasma is considered within the linear response (LR) and binary collision (BC) treatments with the purpose to look for a connection between these two models. These two complementary approaches yield close results if no magnetic field is present, but there develop discrepancies with growing magnetic field at ion velocities that are lower than, or comparable with, the thermal velocity of the electrons. We show that this is a peculiarity of the Coulomb interaction which requires cutoff procedures to account for its singularity at the origin and its infinite range. The cutoff procedures in the LR and BC treatments are different as the order of integrations in velocity and in ordinary (Fourier) spaces is reversed in both treatments. While BC involves a velocity average of Coulomb logarithms, there appear in LR Coulomb logarithms of velocity averaged cutoffs. The discrepancies between LR and BC vanish, except for small contributions of collective modes, for smoothened potentials that require no cutoffs. This is shown explicitly with the help of an improved BC in which the velocity transfer is treated up to second order in the interaction in Fourier space.

  16. Nonequilibrium response of a voltage gated sodium ion channel and biophysical characterization of dynamic hysteresis.

    PubMed

    Pal, Krishnendu; Das, Biswajit; Gangopadhyay, Gautam

    2017-02-21

    Here we have studied the dynamic as well as the non-equilibrium thermodynamic response properties of voltage-gated Na-ion channel. Using sinusoidally oscillating external voltage protocol we have both kinetically and energetically studied the non-equilibrium steady state properties of dynamic hysteresis in details. We have introduced a method of estimating the work done associated with the dynamic memory due to a cycle of oscillating voltage. We have quantitatively characterised the loop area of ionic current which gives information about the work done to sustain the dynamic memory only for ion conduction, while the loop area of total entropy production rate gives the estimate of work done for overall gating dynamics. The maximum dynamic memory of Na-channel not only depends on the frequency and amplitude but it also depends sensitively on the mean of the oscillating voltage and here we have shown how the system optimize the dynamic memory itself in the biophysical range of field parameters. The relation between the average ionic current with increasing frequency corresponds to the nature of the average dissipative work done at steady state. It is also important to understand that the utilization of the energy from the external field can not be directly obtained only from the measurement of ionic current but also requires nonequilibrium thermodynamic study.

  17. Metabolic simulation chamber

    NASA Technical Reports Server (NTRS)

    Bartlett, R. G.; Hendricks, C. M.

    1972-01-01

    Metabolic simulation combustion chamber was developed as subsystem for breathing metabolic simulator. Entire system is used for evaluation of life support and resuscitation equipment. Metabolism subsystem simulates a human by consuming oxygen and producing carbon dioxide. Basic function is to simulate human metabolic range from rest to hard work.

  18. Improved wire chamber

    DOEpatents

    Atac, M.

    1987-05-12

    An improved gas mixture for use with proportional counter devices, such as Geiger-Mueller tubes and drift chambers. The improved gas mixture provides a stable drift velocity while eliminating wire aging caused by prior art gas mixtures. The new gas mixture is comprised of equal parts argon and ethane gas and having approximately 0.25% isopropyl alcohol vapor. 2 figs.

  19. Coxsackievirus B3 VLPs purified by ion exchange chromatography elicit strong immune responses in mice.

    PubMed

    Koho, Tiia; Koivunen, Minni R L; Oikarinen, Sami; Kummola, Laura; Mäkinen, Selina; Mähönen, Anssi J; Sioofy-Khojine, Amirbabak; Marjomäki, Varpu; Kazmertsuk, Artur; Junttila, Ilkka; Kulomaa, Markku S; Hyöty, Heikki; Hytönen, Vesa P; Laitinen, Olli H

    2014-04-01

    Coxsackievirus B3 (CVB3) is an important cause of acute and chronic viral myocarditis, and dilated cardiomyopathy (DCM). Although vaccination against CVB3 could significantly reduce the incidence of serious or fatal viral myocarditis and various other diseases associated with CVB3 infection, there is currently no vaccine or therapeutic reagent in clinical use. In this study, we contributed towards the development of a CVB3 vaccine by establishing an efficient and scalable ion exchange chromatography-based purification method for CVB3 virus and baculovirus-insect cell-expressed CVB3 virus-like particles (VLPs). This purification system is especially relevant for vaccine development and production on an industrial scale. The produced VLPs were characterized using a number of biophysical methods and exhibited excellent quality and high purity. Immunization of mice with VLPs elicited a strong immune response, demonstrating the excellent vaccine potential of these VLPs.

  20. Assessment of Early Toxicity and Response in Patients Treated With Proton and Carbon Ion Therapy at the Heidelberg Ion Therapy Center Using the Raster Scanning Technique

    SciTech Connect

    Rieken, Stefan; Habermehl, Daniel; Nikoghosyan, Anna; Jensen, Alexandra; Haberer, Thomas; Jaekel, Oliver; Muenter, Marc W.; Welzel, Thomas; Debus, Juergen; Combs, Stephanie E.

    2011-12-01

    Puropose: To asses early toxicity and response in 118 patients treated with scanned ion beams to validate the safety of intensity-controlled raster scanning at the Heidelberg Ion Therapy Center. Patients and Methods: Between November 2009 and June 2010, we treated 118 patients with proton and carbon ion radiotherapy (RT) using active beam delivery. The main indications included skull base chordomas and chondrosarcomas, salivary gland tumors, and gliomas. We evaluated early toxicity within 6 weeks after RT and the initial clinical and radiologic response for quality assurance in our new facility. Results: In all 118 patients, few side effects were observed, in particular, no high numbers of severe acute toxicity were found. In general, the patients treated with particle therapy alone showed only a few single side effects, mainly Radiation Therapy Oncology Group/Common Terminology Criteria grade 1. The most frequent side effects and cumulative incidence of single side effects were observed in the head-and-neck patients treated with particle therapy as a boost and photon intensity-modulated RT. The toxicities included common radiation-attributed reactions known from photon RT, including mucositis, dysphagia, and skin erythema. The most predominant imaging responses were observed in patients with high-grade gliomas and those with salivary gland tumors. For skull base tumors, imaging showed a stable tumor outline in most patients. Thirteen patients showed improvement of pre-existing clinical symptoms. Conclusions: Side effects related to particle treatment were rare, and the overall tolerability of the treatment was shown. The initial response was promising. The data have confirmed the safe delivery of carbon ions and protons at the newly opened Heidelberg facility.

  1. Nonlinear luminescence response of CaF2:Eu and YAlO3:Ce to single-ion excitation

    SciTech Connect

    Liu, Peng; Zhang, Yanwen; Xiao, Haiyan; Xiang, Xia; Wang, Xuelin; Weber, William J.

    2014-01-21

    Pulse-height of CaF2:Eu and YAlO3:Ce scintillators to single H+, He+ and O3+ ions are measured over a continuous energy range using a time-of-flight (TOF) - scintillator - photoelectric multiplier tube (PMT) apparatus. A nonlinear response of the scintillators under ionizing ion irradiation is quantitatively evaluated by considering energy partitioning process. The results show that, in a differential energy deposition region with negligible displacement damage, the low, medium and high excitation energy deposition density (Dexci) produced by H+, He+ and O3+ ions irradiation, respectively, have significantly different impacts on the response characteristics of these two benchmark scintillators. For CaF2:Eu, the scintillation efficiency under ion irradiation monotonically decreases with increasing excitation-energy density. In contrast, the response efficiency of YAlO3:Ce scintillation initially increases with excitation-energy density at low excitation-energy densities, goes through a maximum, and then decreases with further increasing excitation-energy density. The fundamental mechanism causing these different response behaviours in the scintillators is based on the competition between the scintillation response and the nonradiative quenching process under different excitation densities, which is also the main origin of the nonlinear response of scintillators to irradiation.

  2. TL response of Eu activated LiF nanocubes irradiated by 85 MeV carbon ions

    NASA Astrophysics Data System (ADS)

    Salah, Numan; Alharbi, Najlaa D.; Habib, Sami S.; Lochab, S. P.

    2015-09-01

    Carbon ions were found to be effective for cancer treatment. These heavy ions have a high relative biological effectiveness compared to those of photons. They have higher linear energy transfer and sharper Bragg peak with a very excellent local tumor control. However, the dose of these swift heavy ions needs to be measured with great accuracy. Lithium fluoride (LiF) is a highly sensitive phosphor widely used for radiation dosimetry. In this work Eu activated LiF nanocubes were exposed to 85 MeV C6+ ion beam and evaluated for their thermoluminescence (TL) response. Pellet forms of this nanomaterial were exposed to these ions in the fluence range 109-1013 ions/cm2. The obtained result shows a prominent TL glow peak at around 320 °C, which is different than that induced by gamma rays. This glow peak exhibits a linear response in the range 109-1012 ions/cm2, corresponding to the equivalent absorbed doses 0.273-273 kGy. The absorbed doses, penetration depths and main energy loss were calculated using TRIM code based on the Monte Carlo simulation. The supralinearity function and stopping power in this nanomaterial were also studied. The modification induced in the glow curve structure as a result of changing irradiation type might be utilized to use LiF:Eu nanocubes as a dosimeter for mixed filed radiations. Moreover, the wide linear response of LiF:Eu nanocubes along with the low fading are another imperative results suggesting that this nanomaterial might be a good candidate for carbon ions dosimetry.

  3. Combustor with fuel preparation chambers

    NASA Technical Reports Server (NTRS)

    Zelina, Joseph (Inventor); Myers, Geoffrey D. (Inventor); Srinivasan, Ram (Inventor); Reynolds, Robert S. (Inventor)

    2001-01-01

    An annular combustor having fuel preparation chambers mounted in the dome of the combustor. The fuel preparation chamber comprises an annular wall extending axially from an inlet to an exit that defines a mixing chamber. Mounted to the inlet are an air swirler and a fuel atomizer. The air swirler provides swirled air to the mixing chamber while the atomizer provides a fuel spray. On the downstream side of the exit, the fuel preparation chamber has an inwardly extending conical wall that compresses the swirling mixture of fuel and air exiting the mixing chamber.

  4. Multi-chamber deposition system

    DOEpatents

    Jacobson, Richard L.; Jeffrey, Frank R.; Westerberg, Roger K.

    1989-10-17

    A system for the simultaneous deposition of different coatings onto a thin web within a large volume vacuum chamber is disclosed which chamber is provided with a plurality of deposition chambers in which the different layers are deposited onto the film as its moves from a supply roll to a finished take-up roll of coated web. The deposition chambers provided within the large vacuum chamber are provided with separate seals which minimize back diffusion of any dopant gas from adjacent deposition chambers.

  5. Multi-chamber deposition system

    DOEpatents

    Jacobson, Richard L.; Jeffrey, Frank R.; Westerberg, Roger K.

    1989-06-27

    A system for the simultaneous deposition of different coatings onto a thin web within a large volume vacuum chamber is disclosed which chamber is provided with a plurality of deposition chambers in which the different layers are deposited onto the film as its moves from a supply roll to a finished take-up roll of coated web. The deposition chambers provided within the large vacuum chamber are provided with separate seals which minimize back diffusion of any dopant gas from adjacent deposition chambers.

  6. 72. VISITOR'S CENTER, MODEL OF BOILER CHAMBER, AUXILIARY CHAMBER, REACTOR ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    72. VISITOR'S CENTER, MODEL OF BOILER CHAMBER, AUXILIARY CHAMBER, REACTOR AND CANAL (LOCATION T) - Shippingport Atomic Power Station, On Ohio River, 25 miles Northwest of Pittsburgh, Shippingport, Beaver County, PA

  7. A Customizable Chamber for Measuring Cell Migration.

    PubMed

    Chowdhury, Aniqa N; Vo, Huu Tri; Olang, Sharon; Mappus, Elliott; Peterson, Brian; Hlavac, Nora; Harvey, Tyler; Dean, Delphine

    2017-03-12

    Cell migration is a vital part of immune responses, growth, and wound healing. Cell migration is a complex process that involves interactions between cells, the extracellular matrix, and soluble and non-soluble chemical factors (e.g., chemoattractants). Standard methods for measuring the migration of cells, such as the Boyden chamber assay, work by counting cells on either side of a divider. These techniques are easy to use; however, they offer little geometric modification for different applications. In contrast, microfluidic devices can be used to observe cell migration with customizable concentration gradients of soluble factors(1)(,)(2). However, methods for making microfluidics based assays can be difficult to learn. Here, we describe an easy method for creating cell culture chambers to measure cell migration in response to chemical concentration gradients. Our cell migration chamber method can create different linear concentration gradients in order to study cell migration for a variety of applications. This method is relatively easy to use and is typically performed by undergraduate students. The microchannel chamber was created by placing an acrylic insert in the shape of the final microchannel chamber well into a Petri dish. After this, poly(dimethylsiloxane) (PDMS) was poured on top of the insert. The PDMS was allowed to harden and then the insert was removed. This allowed for the creation of wells in any desired shape or size. Cells may be subsequently added to the microchannel chamber, and soluble agents can be added to one of the wells by soaking an agarose block in the desired agent. The agarose block is added to one of the wells, and time-lapse images can be taken of the microchannel chamber in order to quantify cell migration. Variations to this method can be made for a given application, making this method highly customizable.

  8. Modulation of gene expression in endothelial cells in response to high LET nickel ion irradiation.

    PubMed

    Beck, Michaël; Rombouts, Charlotte; Moreels, Marjan; Aerts, An; Quintens, Roel; Tabury, Kevin; Michaux, Arlette; Janssen, Ann; Neefs, Mieke; Ernst, Eric; Dieriks, Birger; Lee, Ryonfa; De Vos, Winnok H; Lambert, Charles; Van Oostveldt, Patrick; Baatout, Sarah

    2014-10-01

    Ionizing radiation can elicit harmful effects on the cardiovascular system at high doses. Endothelial cells are critical targets in radiation-induced cardiovascular damage. Astronauts performing a long-term deep space mission are exposed to consistently higher fluences of ionizing radiation that may accumulate to reach high effective doses. In addition, cosmic radiation contains high linear energy transfer (LET) radiation that is known to produce high values of relative biological effectiveness (RBE). The aim of this study was to broaden the understanding of the molecular response to high LET radiation by investigating the changes in gene expression in endothelial cells. For this purpose, a human endothelial cell line (EA.hy926) was irradiated with accelerated nickel ions (Ni) (LET, 183 keV/µm) at doses of 0.5, 2 and 5 Gy. DNA damage was measured 2 and 24 h following irradiation by γ-H2AX foci detection by fluorescence microscopy and gene expression changes were measured by microarrays at 8 and 24 h following irradiation. We found that exposure to accelerated nickel particles induced a persistent DNA damage response up to 24 h after treatment. This was accompanied by a downregulation in the expression of a multitude of genes involved in the regulation of the cell cycle and an upregulation in the expression of genes involved in cell cycle checkpoints. In addition, genes involved in DNA damage response, oxidative stress, apoptosis and cell-cell signaling (cytokines) were found to be upregulated. An in silico analysis of the involved genes suggested that the transcription factors, E2F and nuclear factor (NF)-κB, may be involved in these cellular responses.

  9. Electro-responsive asymmetric nanopores in polyimide with stable ion-current signal

    NASA Astrophysics Data System (ADS)

    Siwy, Z.; Dobrev, D.; Neumann, R.; Trautmann, C.; Voss, K.

    For the preparation of a single asymmetrically shaped nanopore in a polyimide membrane, Kapton foils were irradiated with single heavy ions and subsequently etched from one side in sodium hypochlorite (NaOCl). The other side of the membrane was protected from etching by a stopping medium containing a reducing agent for hypochlorite ions (OCl-). The resulting conical nanopore rectified ion current and exhibited a stable ion-current flow.

  10. A smart temperature and magnetic-responsive gating carbon nanotube membrane for ion and protein transportation

    NASA Astrophysics Data System (ADS)

    Cong, Hailin; Xu, Xiaodan; Yu, Bing; Yang, Zhaohui; Zhang, Xiaoyan

    2016-08-01

    Carbon nanotube (CNT) nanoporous membranes based on pre-aligned CNTs have superior nano-transportation properties in biological science. Herein, we report a smart temperature- and temperature-magnetic-responsive CNT nanoporous membrane (CNM) by grafting thermal-sensitive poly(N-isopropylacrylamide) (PNIPAM) and Fe3O4 nanoparticles (Fe3O4-NPs) on the open ends of pre-aligned CNTs with a diameter around 15 nm via surface-initiated atom transfer radical polymerization (SI-ATRP) method. The inner cavity of the modified CNTs in the membrane is designed to be the only path for ion and protein transportation, and its effective diameter with a variation from ~5.7 nm to ~12.4 nm can be reversible tuned by temperature and magnetic field. The PNIPAM modified CNM (PNIPAM-CNM) and PNIPAM magnetic nanoparticles modified CNM (PNIPAM-MAG-CNM) exhibit excellent temperature- or temperature-magnetic-responsive gating property to separate proteins of different sizes. The PNIPAM-CNMs and PNIPAM-MAG-CNMs have potential applications in making artificial cells, biosensors, bioseparation and purification filters.

  11. A smart temperature and magnetic-responsive gating carbon nanotube membrane for ion and protein transportation

    PubMed Central

    Cong, Hailin; Xu, Xiaodan; Yu, Bing; Yang, Zhaohui; Zhang, Xiaoyan

    2016-01-01

    Carbon nanotube (CNT) nanoporous membranes based on pre-aligned CNTs have superior nano-transportation properties in biological science. Herein, we report a smart temperature- and temperature-magnetic-responsive CNT nanoporous membrane (CNM) by grafting thermal-sensitive poly(N-isopropylacrylamide) (PNIPAM) and Fe3O4 nanoparticles (Fe3O4-NPs) on the open ends of pre-aligned CNTs with a diameter around 15 nm via surface-initiated atom transfer radical polymerization (SI-ATRP) method. The inner cavity of the modified CNTs in the membrane is designed to be the only path for ion and protein transportation, and its effective diameter with a variation from ~5.7 nm to ~12.4 nm can be reversible tuned by temperature and magnetic field. The PNIPAM modified CNM (PNIPAM-CNM) and PNIPAM magnetic nanoparticles modified CNM (PNIPAM-MAG-CNM) exhibit excellent temperature- or temperature-magnetic-responsive gating property to separate proteins of different sizes. The PNIPAM-CNMs and PNIPAM-MAG-CNMs have potential applications in making artificial cells, biosensors, bioseparation and purification filters. PMID:27535103

  12. Hierarchical Bayesian inference for ion channel screening dose-response data

    PubMed Central

    2016-01-01

    Dose-response (or ‘concentration-effect’) relationships commonly occur in biological and pharmacological systems and are well characterised by Hill curves. These curves are described by an equation with two parameters: the inhibitory concentration 50% (IC50); and the Hill coefficient. Typically just the ‘best fit’ parameter values are reported in the literature. Here we introduce a Python-based software tool, PyHillFit, and describe the underlying Bayesian inference methods that it uses, to infer probability distributions for these parameters as well as the level of experimental observation noise. The tool also allows for hierarchical fitting, characterising the effect of inter-experiment variability. We demonstrate the use of the tool on a recently published dataset on multiple ion channel inhibition by multiple drug compounds. We compare the maximum likelihood, Bayesian and hierarchical Bayesian approaches. We then show how uncertainty in dose-response inputs can be characterised and propagated into a cardiac action potential simulation to give a probability distribution on model outputs. PMID:27918599

  13. Hierarchical Bayesian inference for ion channel screening dose-response data.

    PubMed

    Johnstone, Ross H; Bardenet, Rémi; Gavaghan, David J; Mirams, Gary R

    2016-01-01

    Dose-response (or 'concentration-effect') relationships commonly occur in biological and pharmacological systems and are well characterised by Hill curves. These curves are described by an equation with two parameters: the inhibitory concentration 50% (IC50); and the Hill coefficient. Typically just the 'best fit' parameter values are reported in the literature. Here we introduce a Python-based software tool, PyHillFit , and describe the underlying Bayesian inference methods that it uses, to infer probability distributions for these parameters as well as the level of experimental observation noise. The tool also allows for hierarchical fitting, characterising the effect of inter-experiment variability. We demonstrate the use of the tool on a recently published dataset on multiple ion channel inhibition by multiple drug compounds. We compare the maximum likelihood, Bayesian and hierarchical Bayesian approaches. We then show how uncertainty in dose-response inputs can be characterised and propagated into a cardiac action potential simulation to give a probability distribution on model outputs.

  14. One cubic metre NIST traceable radon test chamber.

    PubMed

    Kotrappa, P; Stieff, F

    2008-01-01

    With the availability of the National Institute of Standards and Technology (NIST) Radon Emanation Standard with a content of approximately 5000 Bq of 226Ra, it is possible to build a flow through a practical radon test chamber. A standard glove box with four gloves and a transfer port is used. Air is pumped through a flow integrator, water jar for humidification and NIST source holder, and into the glove box through a manifold. A derived theoretical expression provides the calculated radon concentration inside the chamber. The calculation includes a derived decay correction due to the large volume and low flow rate of the system. Several calibrated continuous radon monitors and passive integrating electret ion chambers tested in the chamber agreed fairly well with the calculated radon concentrations. The chamber is suitable for handling the calibration of several detectors at the same time.

  15. Multiwire proportional chamber development

    NASA Technical Reports Server (NTRS)

    Doolittle, R. F.; Pollvogt, U.; Eskovitz, A. J.

    1973-01-01

    The development of large area multiwire proportional chambers, to be used as high resolution spatial detectors in cosmic ray experiments is described. A readout system was developed which uses a directly coupled, lumped element delay-line whose characteristics are independent of the MWPC design. A complete analysis of the delay-line and the readout electronic system shows that a spatial resolution of about 0.1 mm can be reached with the MWPC operating in the strictly proportional region. This was confirmed by measurements with a small MWPC and Fe-55 X-rays. A simplified analysis was carried out to estimate the theoretical limit of spatial resolution due to delta-rays, spread of the discharge along the anode wire, and inclined trajectories. To calculate the gas gain of MWPC's of different geometrical configurations a method was developed which is based on the knowledge of the first Townsend coefficient of the chamber gas.

  16. Crystals in magma chambers

    NASA Astrophysics Data System (ADS)

    Higgins, M.

    2011-12-01

    Differentiation processes in igneous systems are one way in which the diversity of igneous rocks is produced. Traditionally, magmatic diversity is considered as variations in the overall chemical composition, such as basalt and rhyolite, but I want to extend this definition to include textural diversity. Such textural variations can be manifested as differences in the amount of crystalline (and immiscible liquid) phases and in the origin and identity of such phases. One important differentiation process is crystal-liquid separation by floatation or decantation, which clearly necessitates crystals in the magma. Hence, it is important to determine if magmas in chambers (sensu lato) have crystals. The following discussion is framed in generalities - many exceptions occur. Diabase (dolerite) dykes are a common, widespread result of regional mafic magmatism. The rims of most diabase dykes have few or no phenocrysts and crystals in the cores are commonly thought to have crystallized in place. Hence, this major mafic magmatic source did not have crystals, although compositional diversity of these dykes is commonly explained by crystal-liquid separation. This can be resolved if crystallisation was on the walls on the magma chamber. Similarly, most flood basalts are low in crystals and separation of those that are present cannot always explain the observed compositional diversity. Crystal-rich flows do occur, for example the 'Giant Plagioclase Basalts' of the Deccan series, but the crystals are thought to form or accumulate in a crystal-rich zone beneath the roof of the chamber - the rest of the chamber probably has few crystals. Some magmas from Hawaii contain significant amounts of olivine crystals, but most of these are deformed and cannot have crystallised in the chamber. In this case the crystals are thought to grow as the magma passes through a decollement zone. They may have grown on the walls or been trapped by filters. Basaltic andesite ignimbrites generally have

  17. Combustion chamber noise suppressor

    SciTech Connect

    Livingston, A.M.

    1986-08-19

    A combustion chamber is described for a hot fog generating machine comprising a hollow cylindrical combustion chamber shell having a closure plate at one end and outlet means at the opposite end for directing hot combustion gasses to a fogging nozzle, air inlet means disposed adjacent the outlet means, fuel inlet means and ignition means mounted in the closure plate and liner means disposed concentrically within the cylindrical combustion chamber for controlling the flow of air and combustion gasses within the shell. The liner means includes a liner base having a frustroconical configuration with the smaller diameter end thereof disposed in communication with the outlet means and with the larger diameter end thereof disposed in spaced relation to the shell, circumferentially spaced, longitudinally extending fins extending outwardly from the liner base intermediate the liner base and the shell, a cylindrical liner midsection having circumferentially spaced fins extending outwardly therefrom between the midsection and the shell with the fins supporting the midsection on the larger diameter end of the liner base.

  18. Segmented ionization chambers for beam monitoring in hadrontherapy

    NASA Astrophysics Data System (ADS)

    Braccini, Saverio; Cirio, Roberto; Donetti, Marco; Marchetto, Flavio; Pittà, Giuseppe; Lavagno, Marco; La Rosa, Vanessa

    2015-05-01

    Segmented ionization chambers represent a good solution to monitor the position, the intensity and the shape of ion beams in hadrontherapy. Pixel and strip chambers have been developed for both passive scattering and active scanning dose delivery systems. In particular, strip chambers are optimal for pencil beam scanning, allowing for spatial and time resolutions below 0.1 mm and 1 ms, respectively. The MATRIX pixel and the Strip Accurate Monitor for Beam Applications (SAMBA) detectors are described in this paper together with the results of several beam tests and industrial developments based on these prototypes.

  19. Microstrip gas chamber on thin-film Pestov glass and micro gap chamber

    SciTech Connect

    Gong, W.G.; Harris, J.W.; Wieman, H.

    1994-07-01

    The authors report developments of the Microstrip Gas Chamber on thin-film Pestov glass and the Micro Gap Chamber. By coating a thin-layer of low-resistive, electronically-conductive glass on various substrates (including quartz and ceramics), they built MSGCs of high gain stability and low leakage current. They were tested in Ar-CH{sub 4} (10%) and He-C{sub 2}H{sub 6} (50%) gas mixtures. Energy resolutions of 17-20% were measured for 6keV x-rays. This design can make the choice of substrate less important, save the cost of ion-implantation, and use less glass material. Micro Gap Chamber was successfully tested in He-C{sub 2}H{sub 6} (50%) and Ar-C{sub 2}H{sub 6}(50%) gas mixtures. Energy resolutions of about 20% were obtained. Both detectors are expected to have high rate capability.

  20. Near-LTE linear response calculations with a collisional-radiative model for He-like Al ions

    SciTech Connect

    More, R.M.; Kato, T.

    1998-01-06

    We investigate the non-equilibrium atomic kinetics using a collisional-radiative (CR) model modified to include line absorption. Steady-state emission is calculated for He-like aluminum ions immersed in a specified radiation field having fixed deviations from a Planck spectrum. The net emission is interpreted in terms of NLTE population changes. The calculation provides an NLTE response matrix, and in agreement with a general relation of non-equilibrium thermodynamics, the response matrix is symmetric. We compute the response matrix for 1% and 50% changes in the photon temperature and find linear response over a surprisingly large range.

  1. Vertical two chamber reaction furnace

    DOEpatents

    Blaugher, R.D.

    1999-03-16

    A vertical two chamber reaction furnace is disclosed. The furnace comprises a lower chamber having an independently operable first heating means for heating the lower chamber and a gas inlet means for admitting a gas to create an ambient atmosphere, and an upper chamber disposed above the lower chamber and having an independently operable second heating means for heating the upper chamber. Disposed between the lower chamber and the upper chamber is a vapor permeable diffusion partition. The upper chamber has a conveyor means for conveying a reactant there through. Of particular importance is the thallinating of long-length thallium-barium-calcium copper oxide (TBCCO) or barium-calcium-copper oxide (BCCO) precursor tapes or wires conveyed through the upper chamber to thereby effectuate the deposition of vaporized thallium (being so vaporized as the first reactant in the lower chamber at a temperature between about 700 and 800 C) on TBCCO or BCCO tape or wire (the second reactant) at its simultaneous annealing temperature in the upper chamber of about 800 to 950 C to thereby replace thallium oxide lost from TBCCO tape or wire because of the high annealing temperature or to deposit thallium on BCCO tape or wire. Continuously moving the tape or wire provides a single-step process that effectuates production of long-length TBCCO superconducting product. 2 figs.

  2. Vertical two chamber reaction furnace

    DOEpatents

    Blaugher, Richard D.

    1999-03-16

    A vertical two chamber reaction furnace. The furnace comprises a lower chamber having an independently operable first heating means for heating the lower chamber and a gas inlet means for admitting a gas to create an ambient atmosphere, and an upper chamber disposed above the lower chamber and having an independently operable second heating means for heating the upper chamber. Disposed between the lower chamber and the upper chamber is a vapor permeable diffusion partition. The upper chamber has a conveyor means for conveying a reactant there through. Of particular importance is the thallinating of long-length thallium-barium-calcium-copper oxide (TBCCO) or barium-calcium-copper oxide (BCCO) precursor tapes or wires conveyed through the upper chamber to thereby effectuate the deposition of vaporized thallium (being so vaporized as the first reactant in the lower chamber at a temperature between about 700.degree. and 800.degree. C.) on TBCCO or BCCO tape or wire (the second reactant) at its simultaneous annealing temperature in the upper chamber of about 800.degree. to 950.degree. C. to thereby replace thallium oxide lost from TBCCO tape or wire because of the high annealing temperature or to deposit thallium on BCCO tape or wire. Continuously moving the tape or wire provides a single-step process that effectuates production of long-length TBCCO superconducting product.

  3. WE-E-BRE-06: High-Dose Microbeam Radiation Induces Different Responses in Tumor Microenvironment Compared to Conventional Seamless Radiation in Window Chamber Tumor Models

    SciTech Connect

    Chang, S; Zhang, J; Hadsell, M; Fontanella, A; Schroeder, T; Palmer, G; Dewhirst, M; Boss, M; Berman, K

    2014-06-15

    Purpose: Microbeam radiation therapy and GRID therapy are different forms of Spatially-Fractioned Radiation Therapy (SFRT) that is fundamentally different from the conventional seamless and temporally fractionated radiation therapy. SFRT is characterized by a ultra-high dose (10s –100s Gy) dose single treatment with drastic inhomogeneity pattern of given spatial frequencies. Preclinical and limited clinical studies have shown that the SFRT treatments may offer significant improvements in reducing treatment toxicity, especially for those patients who have not benefited from the state-of-the-art radiation therapy approaches. This preliminary study aims to elucidate the underlying working mechanisms of SFRT, which currently remains poorly understood. Methods: A genetically engineered 4T1 murine mammary carcinoma cell line and nude mice skin fold window chamber were used. A nanotechnology-based 160kV x-ray irradiator delivered 50Gy (entrance dose) single treatments of microbeam or seamless radiation. Animals were in 3 groups: mock, seamless radiation, and 300μm microbeam radiation. The windows were imaged using a hyperspectral system to capture total hemoglobin/saturation, GFP fluorescence emission, RFP fluorescence emission, and vessel density at 9 time points up to 7 days post radiation. Results: We found unique physiologic changes in different tumor/normal tissue regions and differential effects between seamless and microbeam treatments. They include 1) compared to microbeam and mock radiation seamless radiation damaged more microvasculature in tumor-surrounding normal tissue, 2) a pronounced angiogenic effect was observed with vascular proliferation in the microbeam irradiated portion of the tumor days post treatment (no such effect observed in seamless and mock groups), and 3) a notable change in tumor vascular orientation was observed where vessels initially oriented parallel to the beam length were replaced by vessels running perpendicular to the irradiation

  4. Comparing Single species Toxicity Tests to Mesocosm Community-Level Responses to Total Dissolved Solids Comprised of Different Major Ions

    EPA Science Inventory

    Total Dissolved Solids (TDS) dosing studies representing different sources of ions were conducted from 2011-2015. Emergence responses in stream mesocosms were compared to single-species exposures using a whole effluent testing (WET) format and an ex-situ method (single species te...

  5. Stream periphyton responses to mesocosm treatments of equal specific conductance but different major ion contents measured with in situ fluorometry

    EPA Science Inventory

    A stream mesocosm experiment was designed to compare biotic responses among streams exposed to an equal excess specific conductivity target of 850 µS/cm relative to a control that was set for 200 µS/cm and three treatments comprised of different major ion contents. Each treatment...

  6. Global response of the upper thermospheric winds to large ion drifts in the Jovian ovals

    NASA Astrophysics Data System (ADS)

    Majeed, T.; Bougher, S. W.; Ridley, A. J.; Waite, J. H.; Gladstone, G. R.; Bell, J. M.

    2016-05-01

    We use our fully coupled 3-D Jupiter Thermosphere General Circulation Model (JTGCM) to quantify processes which are responsible for generating neutral winds in Jupiter's oval thermosphere from 20 µbar to 10-4 nbar self-consistently with the thermal structure and composition. The heat sources in the JTGCM that drive the global circulation of neutral flow are substantial Joule heating produced in the Jovian ovals by imposing high-speed anticorotational ion drifts (~3.5 km s-1) and charged particle heating from auroral processes responsible for bright oval emissions. We find that the zonal flow of neutral winds in the auroral ovals of both hemispheres is primarily driven by competition between accelerations resulting from Coriolis forcing and ion drag processes near the ionospheric peak. However, above the ionospheric peak (<0.01 µbar), the acceleration of neutral flow due to pressure gradients is found to be the most effective parameter impacting zonal winds, competing mainly with acceleration due to advection with minor contributions from curvature and Coriolis forces in the southern oval, while in the northern oval it competes alone with considerable Coriolis forcing. The meridional flow of neutral winds in both ovals in the JTGCM is determined by competition between meridional accelerations due to Coriolis forcing and pressure gradients. We find that meridional flow in the lower thermosphere, near the peak of the auroral ionosphere, is poleward, with peak wind speeds of ~0.6 km s-1 and ~0.1 km s-1 in the southern and northern oval, respectively. The corresponding subsiding flow of neutral motion is ~5 m s-1 in the southern oval, while this flow is rising in the northern oval with reduced speed of ~2 m s-1. We also find that the strength of meridional flow in both auroral ovals is gradually weakened and turned equatorward near 0.08 µbar with wind speeds up to ~250 m s-1 (southern oval) and ~75 m s-1 (northern oval). The corresponding neutral motion in this

  7. The Other Shoe: An Early Operant Conditioning Chamber for Pigeons.

    PubMed

    Sakagami, Takayuki; Lattal, Kennon A

    2016-05-01

    We describe an early operant conditioning chamber fabricated by Harvard University instrument maker Ralph Gerbrands and shipped to Japan in 1952 in response to a request of Professor B. F. Skinner by Japanese psychologists. It is a rare example, perhaps the earliest still physically existing, of such a chamber for use with pigeons. Although the overall structure and many of the components are similar to contemporary pigeon chambers, several differences are noted and contrasted to evolutionary changes in this most important laboratory tool in the experimental analysis of behavior. The chamber also is testimony to the early internationalization of behavior analysis.

  8. Air ion exposure system for plants.

    PubMed

    Morrow, R C; Tibbitts, T W

    1987-02-01

    A system was developed for subjecting plants to elevated air ion levels. This system consisted of a rectangular Plexiglas chamber lined with a Faraday cage. Air ions were generated by corona discharge from frayed stainless steel fibers placed at one end of the chamber. This source was capable of producing varying levels of either positive or negative air ions. During plant exposures, environmental conditions were controlled by operating the unit in a growth chamber.

  9. Air ion exposure system for plants

    NASA Technical Reports Server (NTRS)

    Morrow, R. C.; Tibbitts, T. W.

    1987-01-01

    A system was developed for subjecting plants to elevated air ion levels. This system consisted of a rectangular Plexiglas chamber lined with a Faraday cage. Air ions were generated by corona discharge from frayed stainless steel fibers placed at one end of the chamber. This source was capable of producing varying levels of either positive or negative air ions. During plant exposures, environmental conditions were controlled by operating the unit in a growth chamber.

  10. Ion mobility sensor system

    DOEpatents

    Xu, Jun; Watson, David B.; Whitten, William B.

    2013-01-22

    An ion mobility sensor system including an ion mobility spectrometer and a differential mobility spectrometer coupled to the ion mobility spectrometer. The ion mobility spectrometer has a first chamber having first end and a second end extending along a first direction, and a first electrode system that generates a constant electric field parallel to the first direction. The differential mobility spectrometer includes a second chamber having a third end and a fourth end configured such that a fluid may flow in a second direction from the third end to the fourth end, and a second electrode system that generates an asymmetric electric field within an interior of the second chamber. Additionally, the ion mobility spectrometer and the differential mobility spectrometer form an interface region. Also, the first end and the third end are positioned facing one another so that the constant electric field enters the third end and overlaps the fluid flowing in the second direction.

  11. Focal-surface detector for heavy ions

    DOEpatents

    Erskine, John R.; Braid, Thomas H.; Stoltzfus, Joseph C.

    1979-01-01

    A detector of the properties of individual charged particles in a beam includes a gridded ionization chamber, a cathode, a plurality of resistive-wire proportional counters, a plurality of anode sections, and means for controlling the composition and pressure of gas in the chamber. Signals generated in response to the passage of charged particles can be processed to identify the energy of the particles, their loss of energy per unit distance in an absorber, and their angle of incidence. In conjunction with a magnetic spectrograph, the signals can be used to identify particles and their state of charge. The detector is especially useful for analyzing beams of heavy ions, defined as ions of atomic mass greater than 10 atomic mass units.

  12. Intracellular accumulation of indium ions released from nanoparticles induces oxidative stress, proinflammatory response and DNA damage.

    PubMed

    Tabei, Yosuke; Sonoda, Akinari; Nakajima, Yoshihiro; Biju, Vasudevanpillai; Makita, Yoji; Yoshida, Yasukazu; Horie, Masanori

    2016-02-01

    Due to the widespread use of indium tin oxide (ITO), it is important to investigate its effect on human health. In this study, we evaluated the cellular effects of ITO nanoparticles (NPs), indium chloride (InCl3) and tin chloride (SnCl3) using human lung epithelial A549 cells. Transmission electron microscopy and inductively coupled plasma mass spectrometry were employed to study cellular ITO NP uptake. Interestingly, greater uptake of ITO NPs was observed, as compared with soluble salts. ITO NP species released could be divided into two types: 'indium release ITO' or 'tin release ITO'. We incubated A549 cells with indium release ITO, tin release ITO, InCl3 or SnCl2 and investigated oxidative stress, proinflammatory response, cytotoxicity and DNA damage. We found that intracellular reactive oxygen species were increased in cells incubated with indium release ITO, but not tin release ITO, InCl3 or SnCl2. Messenger RNA and protein levels of the inflammatory marker, interleukin-8, also increased following exposure to indium release ITO. Furthermore, the alkaline comet assay revealed that intracellular accumulation of indium ions induced DNA damage. Our results demonstrate that the accumulation of ionic indium, but not ionic tin, from ITO NPs in the intracellular matrix has extensive cellular effects.

  13. Ion-responsive liquid crystals of cellulose nanowhiskers grafted with acrylamide.

    PubMed

    Ye, Daiyong; Yang, Jie

    2015-12-10

    In order to develop a novel application for cellulose nanowhiskers (CNW) produced from the sulfuric acid hydrolysis of cotton, acrylamide (AM) was grafted onto the CNW. The graft reaction of the acrylamide-grafted CNW (AM-g-CNW) was confirmed by Fourier transform infrared spectroscopy (FTIR) and UV-vis spectroscopy. The carbon and nitrogen contents of the AM-g-CNW were measured by elemental analysis and X-ray photoelectron spectroscopy (XPS). The grafting ratios and average degrees of β-1,4-linked anhydro-D-glucose unit substitution were measured. The thermochemical properties of the AM-g-CNW were characterized using thermogravimetric analysis (TG). The glass transition temperatures were determined by differential scanning calorimetry (DSC). The degrees of crystallinity were measured by X-ray diffraction (XRD). The liquid crystalline properties of AM-g-CNW were observed by polarizing optical microscopy (POM). AM-g-CNW had the best grafting ratio, 12.77%, when the AM/CNW molar ratio was 3, c(K2S2O8)/n(CNW) was 0.15, the reaction temperature was 70 °C, and the reaction time was 60 min. The birefringence of AM-g-CNW was responsive to hydroxide ions, which might be useful in applications that benefit from sensitivity towards different ionic species.

  14. Enhanced osteoblast responses to poly ether ether ketone surface modified by water plasma immersion ion implantation.

    PubMed

    Wang, Heying; Lu, Tao; Meng, Fanhao; Zhu, Hongqin; Liu, Xuanyong

    2014-05-01

    Poly ether ether ketone (PEEK) offers a set of characteristics superior for human implants; however, its application is limited by the bio-inert surface property. In this work, PEEK surface was modified using single step plasma immersion ion implantation (PIII) treatment with a gas mixture of water vapor as a plasma resource and argon as an ionization assistant. Field emission scanning electron microscopy, atomic force microscopy and X-ray photoelectron spectroscopy were used to investigate the microstructure and composition of the modified PEEK surface. The water contact angle and zeta-potential of the surfaces were also measured. Osteoblast precursor cells MC3T3-E1 and rat bone mesenchymal stem cells were cultured on the PEEK samples to evaluate their cytocompatibility. The obtained results show that the hydroxyl groups as well as a "ravined structure" are constructed on water PIII modified PEEK. Compared with pristine PEEK, the water PIII treated PEEK is more favorable for osteoblast adhesion, spreading and proliferation, besides, early osteogenic differentiation indicated by the alkaline phosphatase activity is also up-regulated. Our study illustrates enhanced osteoblast responses to the PEEK surface modified by water PIII, which gives positive information in terms of future biomedical applications.

  15. Intracellular accumulation of indium ions released from nanoparticles induces oxidative stress, proinflammatory response and DNA damage

    PubMed Central

    Tabei, Yosuke; Sonoda, Akinari; Nakajima, Yoshihiro; Biju, Vasudevanpillai; Makita, Yoji; Yoshida, Yasukazu; Horie, Masanori

    2016-01-01

    Due to the widespread use of indium tin oxide (ITO), it is important to investigate its effect on human health. In this study, we evaluated the cellular effects of ITO nanoparticles (NPs), indium chloride (InCl3) and tin chloride (SnCl3) using human lung epithelial A549 cells. Transmission electron microscopy and inductively coupled plasma mass spectrometry were employed to study cellular ITO NP uptake. Interestingly, greater uptake of ITO NPs was observed, as compared with soluble salts. ITO NP species released could be divided into two types: ‘indium release ITO’ or ‘tin release ITO’. We incubated A549 cells with indium release ITO, tin release ITO, InCl3 or SnCl2 and investigated oxidative stress, proinflammatory response, cytotoxicity and DNA damage. We found that intracellular reactive oxygen species were increased in cells incubated with indium release ITO, but not tin release ITO, InCl3 or SnCl2. Messenger RNA and protein levels of the inflammatory marker, interleukin-8, also increased following exposure to indium release ITO. Furthermore, the alkaline comet assay revealed that intracellular accumulation of indium ions induced DNA damage. Our results demonstrate that the accumulation of ionic indium, but not ionic tin, from ITO NPs in the intracellular matrix has extensive cellular effects. PMID:26378248

  16. Bioabsorbable zinc ion induced biphasic cellular responses in vascular smooth muscle cells

    PubMed Central

    Ma, Jun; Zhao, Nan; Zhu, Donghui

    2016-01-01

    Bioabsorbable metal zinc (Zn) is a promising new generation of implantable scaffold for cardiovascular and orthopedic applications. In cardiovascular stent applications, zinc ion (Zn2+) will be gradually released into the surrounding vascular tissues from such Zn-containing scaffolds after implantation. However, the interactions between vascular cells and Zn2+ are still largely unknown. We explored the short-term effects of extracellular Zn2+ on human smooth muscle cells (SMCs) up to 24 h, and an interesting biphasic effect of Zn2+ was observed. Lower concentrations (<80 μM) of Zn2+ had no adverse effects on cell viability but promoted cell adhesion, cell spreading, cell proliferation, cell migration, and enhanced the expression of F-actin and vinculin. Cells treated with such lower concentrations of Zn2+ displayed an elongated shape compared to controls without any treatment. In contrast, cells treated with higher Zn2+ concentrations (80–120 μM) had opposite cellular responses and behaviors. Gene expression profiles revealed that the most affected functional genes were related to angiogenesis, inflammation, cell adhesion, vessel tone, and platelet aggregation. Results indicated that Zn has interesting concentration-dependent biphasic effects on SMCs with low concentrations being beneficial to cellular functions. PMID:27248371

  17. A comprehensive secondary ion mass spectrometry analysis of ZnO nanowalls: Correlation to photocatalytic responses

    SciTech Connect

    Bayan, Sayan Satpati, Biswarup; Chakraborty, Purushottam

    2015-03-07

    We report on the visible light induced photocatalytic responses of zinc oxide (ZnO) nanostructures in the form of nanowires and nanowalls grown on aluminum substrates. Morphological and microstructural characteristics of these nanostructures have been analyzed using scanning electron microscopy (SEM) and high resolution electron microscopy (HRTEM). The presence of surface-adsorbed H{sup +}, O{sub 2}{sup −}, and OH{sup −} species on ZnO nanostructures has been established through secondary ion mass spectrometry (SIMS). The relative change in substrate coverage under varying reaction time has also been evidenced through SIMS and is in agreement with SEM observation. Compared to nanowires, oxygen adsorption on ZnO surfaces and subsequent oxygen in-diffusion are found to be prominent for the nanowall-like structures and are seen to be highest for nanowalls grown in lower reaction time. In contrast to nanowires, nanowalls are found to exhibit higher photocatalytic activity and this can be attributed to higher adsorption of oxygen. The photocatalytic activity of the samples under visible light is originated from the native defect-states and the photocatalytic efficiency is largely influenced by the surface-adsorbants. Control of surface adsorption characteristics of the nanowalls upon tuning wall thicknesses can lead to the development of futuristic efficient photocatalytic devices.

  18. The APS ceramic chambers

    SciTech Connect

    Milton, S.; Warner, D.

    1994-07-01

    Ceramics chambers are used in the Advanced Photon Source (APS) machines at the locations of the pulsed kicker and bumper magnets. The ceramic will be coated internally with a resistive paste. The resistance is chosen to allow the low frequency pulsed magnet field to penetrate but not the high frequency components of the circulating beam. Another design goal was to keep the power density experienced by the resistive coating to a minimum. These ceramics, their associated hardware, the coating process, and our recent experiences with them are described.

  19. Inert gas ion thruster

    NASA Technical Reports Server (NTRS)

    Ramsey, W. D.

    1980-01-01

    Inert gas performance with three types of 12 cm diameter magnetoelectrostatic containment (MESC) ion thrusters was tested. The types tested included: (1) a hemispherical shaped discharge chamber with platinum cobalt magnets; (2) three different lengths of the hemispherical chambers with samarium cobalt magnets; and (3) three lengths of the conical shaped chambers with aluminum nickel cobalt magnets. The best argon performance was produced by a 8.0 cm long conical chamber with alnico magnets. The best xenon high mass utilization performance was obtained with the same 8.0 cm long conical thruster. The hemispherical thruster obtained 75 to 87% mass utilization at 185 to 205 eV/ion of singly charged ion equivalent beam.

  20. Li-ion battery shut-off at high temperature caused by polymer phase separation in responsive electrolytes.

    PubMed

    Kelly, Jesse C; Degrood, Nicholas L; Roberts, Mark E

    2015-03-28

    For the purpose of realizing inherently safe high-power Li-ion batteries, a model Li4Ti5O12/LiFePO4 rechargeable battery is investigated using the thermally responsive polymer, poly(benzyl methacrylate), in an ionic liquid. At high temperature, battery operation is inhibited as a result of increased internal resistance caused by polymer and ionic liquid phase separation. Li-ion concentration is shown to affect the phase transition temperature and the extent to which batteries are deactivated.

  1. Ion transfer across a liquid membrane. General solution for the current-potential response of any voltammetric technique.

    PubMed

    Molina, A; Serna, C; Gonzalez, J; Ortuño, J A; Torralba, E

    2009-02-28

    An explicit analytical equation applicable to the study of reversible ion transfer at systems with two liquid/liquid polarizable interfaces is presented. This expression is valid for any multipotential step technique, which are all very adequate for the determination of standard transfer potentials and transport parameters of ions. The expression of the I/E response for linear sweep voltammetry and cyclic voltammetry can also be deduced as a particular case of this equation. The general solution given here is formally similar to that obtained for the application of any multipotential step sequence to a system with a single polarizable interface, since the method followed here is based on the same premises.

  2. Influence of ion bombardment on the photoluminescence response of embedded CdS nanoparticles

    NASA Astrophysics Data System (ADS)

    Mohanta, Dambarudhar; Singh, Fouran; Avasthi, D.; Choudhury, Amarjyoti

    2006-06-01

    Semiconductor nanoparticles (CdS) were fabricated by an inexpensive chemical route using polyvinyl alcohol (PVA) as the dielectric host matrix. Nano-CdS in PVA were subjected to ion irradiation (using oxygen, chlorine and gold) in the medium energy range (80-100 MeV) and under fluence variation of 1011-1013 ions/cm2. The nature of light emission was found to be drastically different in each of the three cases. Photoluminescence spectra of oxygen irradiated samples exhibit band edge emission (2.8 eV) as well as trap related emission (1.76 eV) whereas band edge emission is found to be bleached out for chlorine ion irradiated nano-CdS. The intense broad PL peaks, noticeable in the case of gold ion irradiated samples suggest superposition of the two peaks — namely, band edge emission and trap related emission. Furthermore, in the case of gold ion irradiated nano-CdS, energy shift in the PL spectra reveals variation in size distribution caused by the extra pressure effect of heavy gold ion beams. The mechanism of such a difference as a result of ion irradiation-type and ion-fluence is discussed in detail.

  3. Influence of ion bombardment on the photoluminescence response of embedded CdS nanoparticles

    NASA Astrophysics Data System (ADS)

    Mohanta, Dambarudhar; Singh, Fouran; Avasthi, D. K.; Choudhury, Amarjyoti

    2006-06-01

    Semiconductor nanoparticles (CdS) were fabricated by an inexpensive chemical route using polyvinyl alcohol (PVA) as the dielectric host matrix. Nano-CdS in PVA were subjected to ion irradiation (using oxygen, chlorine and gold) in the medium energy range (80 100 MeV) and under fluence variation of 1011 1013 ions/cm2. The nature of light emission was found to be drastically different in each of the three cases. Photoluminescence spectra of oxygen irradiated samples exhibit band edge emission (2.8 eV) as well as trap related emission (1.76 eV) whereas band edge emission is found to be bleached out for chlorine ion irradiated nano-CdS. The intense broad PL peaks, noticeable in the case of gold ion irradiated samples suggest superposition of the two peaks — namely, band edge emission and trap related emission. Furthermore, in the case of gold ion irradiated nano-CdS, energy shift in the PL spectra reveals variation in size distribution caused by the extra pressure effect of heavy gold ion beams. The mechanism of such a difference as a result of ion irradiation-type and ion-fluence is discussed in detail.

  4. Production of N[sup +] ions from a multicusp ion beam apparatus

    DOEpatents

    Kango Leung; Kunkel, W.B.; Walther, S.R.

    1993-03-30

    A method of generating a high purity (at least 98%) N[sup +] ion beam using a multicusp ion source having a chamber formed by a cylindrical chamber wall surrounded by a plurality of magnets, a filament centrally disposed in said chamber, a plasma electrode having an extraction orifice at one end of the chamber, a magnetic filter having two parallel magnets spaced from said plasma electrode and dividing the chamber into arc discharge and extraction regions. The method includes ionizing nitrogen gas in the arc discharge region of the chamber, maintaining the chamber wall at a positive voltage relative to the filament and at a magnitude for an optimum percentage of N[sup +] ions in the extracted ion beams, disposing a hot liner within the chamber and near the chamber wall to limit recombination of N[sup +] ions into the N[sub 2][sup +] ions, spacing the magnets of the magnetic filter from each other for optimum percentage of N[sup 3] ions in the extracted ion beams, and maintaining a relatively low pressure downstream of the extraction orifice and of a magnitude (preferably within the range of 3-8[times]10[sup [minus]4] torr) for an optimum percentage of N[sup +] ions in the extracted ion beam.

  5. Production of N.sup.+ ions from a multicusp ion beam apparatus

    DOEpatents

    Leung, Ka-Ngo; Kunkel, Wulf B.; Walther, Steven R.

    1993-01-01

    A method of generating a high purity (at least 98%) N.sup.+ ion beam using a multicusp ion source (10) having a chamber (11) formed by a cylindrical chamber wall (12) surrounded by a plurality of magnets (13), a filament (57) centrally disposed in said chamber, a plasma electrode (36) having an extraction orifice (41) at one end of the chamber, a magnetic filter having two parallel magnets (21, 22) spaced from said plasma electrode (36) and dividing the chamber (11) into arc discharge and extraction regions. The method includes ionizing nitrogen gas in the arc discharge region of the chamber (11), maintaining the chamber wall (12) at a positive voltage relative to the filament (57) and at a magnitude for an optimum percentage of N.sup.+ ions in the extracted ion beams, disposing a hot liner (45) within the chamber and near the chamber wall (12) to limit recombination of N.sup.+ ions into the N.sub.2.sup.+ ions, spacing the magnets (21, 22) of the magnetic filter from each other for optimum percentage of N.sup.3 ions in the extracted ion beams, and maintaining a relatively low pressure downstream of the extraction orifice and of a magnitude (preferably within the range of 3-8.times.10.sup.-4 torr) for an optimum percentage of N.sup.+ ions in the extracted ion beam.

  6. Light-induced transient ion flux responses from maize leaves and their association with leaf growth and photosynthesis.

    PubMed

    Zivanović, B D; Pang, J; Shabala, S

    2005-03-01

    Net fluxes of H+, K+ and Ca2+ ions from maize (Zea mays L.) isolated leaf segments were measured non-invasively using ion-selective vibrating microelectrodes (the MIFE technique). Leaf segments were isolated from the blade base, containing actively elongating cells (basal segments), and from non-growing tip regions (tip segments). Ion fluxes were measured in response to bright white light (2600 micromoles m-2 s-1) from either the leaf segments or the underlying mesophyll (after stripping the epidermis). Fluxes measured from the mesophyll showed no significant difference between basal and tip regions. In leaf segments (epidermis attached), light-induced flux kinetics of all ions measured (H+, Ca2+ and K+) were strikingly different between the two regions. It appears that epidermal K+ fluxes are required to drive leaf expansion growth, whereas in the mesophyll light-induced K+ flux changes are likely to play a charge balancing role. Light-stimulated Ca2+ influx was not directly attributable either to leaf photosynthetic performance or to leaf expansion growth. It is concluded that light-induced ion flux changes are associated with both leaf growth and photosynthesis.

  7. A guide to Ussing chamber studies of mouse intestine

    PubMed Central

    Clarke, Lane L.

    2009-01-01

    The Ussing chamber provides a physiological system to measure the transport of ions, nutrients, and drugs across various epithelial tissues. One of the most studied epithelia is the intestine, which has provided several landmark discoveries regarding the mechanisms of ion transport processes. Adaptation of this method to mouse intestine adds the dimension of investigating genetic loss or gain of function as a means to identify proteins or processes affecting transepithelial transport. In this review, the principles underlying the use of Ussing chambers are outlined including limitations and advantages of the technique. With an emphasis on mouse intestinal preparations, the review covers chamber design, commercial equipment sources, tissue preparation, step-by-step instruction for operation, troubleshooting, and examples of interpretation difficulties. Specialized uses of the Ussing chamber such as the pH stat technique to measure transepithelial bicarbonate secretion and isotopic flux methods to measure net secretion or absorption of substrates are discussed in detail, and examples are given for the adaptation of Ussing chamber principles to other measurement systems. The purpose of the review is to provide a practical guide for investigators who are new to the Ussing chamber method. PMID:19342508

  8. Development of a microwave ion source for ion implantations

    SciTech Connect

    Takahashi, N. Murata, H.; Kitami, H.; Mitsubori, H.; Sakuraba, J.; Soga, T.; Aoki, Y.; Katoh, T.

    2016-02-15

    A microwave ion source is expected to have a long lifetime, as it has fewer consumables. Thus, we are in the process of developing a microwave ion source for ion implantation applications. In this paper, we report on a newly developed plasma chamber and the extracted P{sup +} beam currents. The volume of the plasma chamber is optimized by varying the length of a boron nitride block installed within the chamber. The extracted P{sup +} beam current is more than 30 mA, at a 25 kV acceleration voltage, using PH{sub 3} gas.

  9. Development of a microwave ion source for ion implantations

    NASA Astrophysics Data System (ADS)

    Takahashi, N.; Murata, H.; Kitami, H.; Mitsubori, H.; Sakuraba, J.; Soga, T.; Aoki, Y.; Katoh, T.

    2016-02-01

    A microwave ion source is expected to have a long lifetime, as it has fewer consumables. Thus, we are in the process of developing a microwave ion source for ion implantation applications. In this paper, we report on a newly developed plasma chamber and the extracted P+ beam currents. The volume of the plasma chamber is optimized by varying the length of a boron nitride block installed within the chamber. The extracted P+ beam current is more than 30 mA, at a 25 kV acceleration voltage, using PH3 gas.

  10. Is the storm time response of the inner magnetospheric hot ions universally similar or driver dependent?

    NASA Astrophysics Data System (ADS)

    Liemohn, Michael W.; Katus, Roxanne

    2012-04-01

    The Hot Electron and Ion Drift Integrator (HEIDI) model was used to simulate all of the intense storms (Dstmin < -100 nT) from solar cycle 23 (1996-2005). These storms were classified according to their heliospheric driving structure, namely, either an interplanetary coronal mass ejection (ICME) or a corotating interaction region and its trailing high-speed stream (CIR/HSS). Five different HEIDI input combinations were used to create a large collection of numerical results, varying the plasma outer boundary condition and electric field description in the model. Statistical data-model analyses were conducted on the total energy content, yielding error estimates on the correlation coefficients and root-mean-square error values for each run set. The accuracy of each run set depends on the method of comparison and classification of the driver. For the correlation coefficients, the simulations using a local-time-dependent outer boundary condition were consistently better than those using a local-time-averaged (but high-time-resolution) nightside boundary condition, with the simplistic electric field being better than the self-consistent field description. For the root-mean-square error, the results are less conclusive. For the CIR/HSS-driven storms, those with the high-time-resolution boundary condition were systematically better than those with the local-time-dependent (but lower-time-resolution) boundary condition. For the ICME-driven storms, those run sets employing the self-consistent electric field calculation were systematically better than those using the simplistic electric field. The implication, therefore, is that the inner magnetospheric physical response to strong driving is, at least to some degree, fundamentally different depending on the heliospheric structure impacting geospace. Specifically, for an accurate SYMH* comparison, it is found that CIR/HSS events respond strongly to transient spikes in the plasma outer boundary condition, while ICME passages

  11. Mush Column Magma Chambers

    NASA Astrophysics Data System (ADS)

    Marsh, B. D.

    2002-12-01

    Magma chambers are a necessary concept in understanding the chemical and physical evolution of magma. The concept may well be similar to a transfer function in circuit or time series analysis. It does what needs to be done to transform source magma into eruptible magma. In gravity and geodetic interpretations the causative body is (usually of necessity) geometrically simple and of limited vertical extent; it is clearly difficult to `see' through the uppermost manifestation of the concentrated magma. The presence of plutons in the upper crust has reinforced the view that magma chambers are large pots of magma, but as in the physical representation of a transfer function, actual magma chambers are clearly distinct from virtual magma chambers. Two key features to understanding magmatic systems are that they are vertically integrated over large distances (e.g., 30-100 km), and that all local magmatic processes are controlled by solidification fronts. Heat transfer considerations show that any viable volcanic system must be supported by a vertically extensive plumbing system. Field and geophysical studies point to a common theme of an interconnected stack of sill-like structures extending to great depth. This is a magmatic Mush Column. The large-scale (10s of km) structure resembles the vertical structure inferred at large volcanic centers like Hawaii (e.g., Ryan et al.), and the fine scale (10s to 100s of m) structure is exemplified by ophiolites and deeply eroded sill complexes like the Ferrar dolerites of the McMurdo Dry Valleys, Antarctica. The local length scales of the sill reservoirs and interconnecting conduits produce a rich spectrum of crystallization environments with distinct solidification time scales. Extensive horizontal and vertical mushy walls provide conditions conducive to specific processes of differentiation from solidification front instability to sidewall porous flow and wall rock slumping. The size, strength, and time series of eruptive behavior

  12. Kinetic response of ionospheric ions to onset of auroral electric fields

    NASA Technical Reports Server (NTRS)

    Chiu, Y. T.; Kan, J. R.

    1981-01-01

    By examining the exact analytic solution of a kinetic model of collisional interaction of ionospheric ions with atmospheric neutrals in the Bhatnagar-Gross-Krook approximation, we show that the onset of intense auroral electric fields in the topside ionosphere can produce the following kinetic effects: (1) heat the bulk ionospheric ions to approximately 2 eV, thus driving them up to higher altitudes where they can be subjected to collisionless plasma processes; (2) produce a non-Maxwellian superthermal tail in the distribution function; and (3) cause the ion distribution function to be anisotropic with respect to the magnetic field with the perpendicular average thermal energy exceeding the parallel thermal energy.

  13. Optimisation of process parameters for adsorption of metal ions on straw carbon by using response surface methodology.

    PubMed

    Kannan, N; Rajakumar, A; Rengasamy, G

    2004-05-01

    Optimisation of process parameters for adsorption of metal ions viz., Cu2+, Cd2+ and Ni2+ ions on Straw Carbon (SC) was carried out by using Box-Behnken statistics and analysis of variance methods. Response surface methodology with three levels of initial pH (4, 5, 6), dose (8, 10, 12 gl(-1)) and particle size (0.075, 0.090, 0.106m micron) were used in the identification of significance of the effects and interactions in adsorption studies. Response surface methodology requires no assumption and identifies the principal experimental variables and their interactions which have the greatest effect on adsorption. The optimum process parameters for maximum adsorption of Ni2+, Cu2+ and Cd2+ were obtained by this procedure.

  14. HATCH CONNECTING TEMPERED AIR CHAMBER AND HOT AIR CHAMBER OF ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    HATCH CONNECTING TEMPERED AIR CHAMBER AND HOT AIR CHAMBER OF PLENUM WITH ATTACHED DRAFT REGULATOR. - Hot Springs National Park, Bathhouse Row, Superior Bathhouse: Mechanical & Piping Systems, State Highway 7, 1 mile north of U.S. Highway 70, Hot Springs, Garland County, AR

  15. Effect of silver nanoparticles and silver ions on growth and adaptive response mechanisms of Pseudomonas putida mt-2.

    PubMed

    Hachicho, Nancy; Hoffmann, Philipp; Ahlert, Kristin; Heipieper, Hermann J

    2014-06-01

    The distribution and use of nanoparticles increased rapidly during the last years, while the knowledge about mode of action, ecological tolerance and biodegradability of these chemicals is still insufficient. The effect of silver nanoparticles (AgNP) and free silver ions (Ag(+) , AgNO3 ) on Pseudomonas putida mt-2 as one of the best described bacterial strains for stress response were investigated. The effective concentration (EC50) causing 50% growth inhibition for AgNP was about 250 mg L(-1) , whereas this was only 0.175 mg L(-1) for AgNO3 . However, when calculating the amount of free silver ions released from AgNP both tested compounds showed very similar results. Therefore, the antibacterial activity of AgNP can be explained and reduced, respectively, to the amount of silver ions released from the nanoparticles. Both tested compounds showed a strong activation of the unique membrane adaptive response of Pseudomonas strains, the cis-trans isomerization of unsaturated fatty acids, whereas another important adaptive response of these bacteria, changes in cell surface hydrophobicity, measured as water contact angle, was not activated. These results are important informations for the estimation of environmental tolerance of newly developed, active ingredients like silver nanoparticles.

  16. The Mechanism Responsible for Extraordinary Cs-ion Selectivity in Crystalline Silicotitanate

    SciTech Connect

    Celestian,A.; Kubicki, J.; Hanson, J.; Clearfield, A.; Parise, J.

    2008-01-01

    Combining information from time-resolved X-ray and neutron scattering with theoretical calculations has revealed the elegant mechanism whereby hydrogen crystalline silicotitanate (H-CST; H2Ti2SiO7{center_dot}1.5H2O) achieves its remarkable ion-exchange selectivity for cesium. Rather than a simple ion-for-ion displacement reaction into favorable sites, which has been suggested by static structural studies of ion-exchanged variants of CST, Cs+ exchange proceeds via a two-step process mediated by conformational changes in the framework. Similar to the case of ion channels in proteins, occupancy of the most favorable site does not occur until the first lever, cooperative repulsive interactions between water and the initial Cs-exchange site, repels a hydrogen lever on the silicotitanate framework. Here we show that these interactions induce a subtle conformational rearrangement in CST that unlocks the preferred Cs site and increases the overall capacity and selectivity for ion exchange.

  17. Response of Cloud Condensation Nuclei (> 50 nm) to changes in ion-nucleation

    NASA Astrophysics Data System (ADS)

    Pedersen, J. O.; Enghoff, M. B.; Svensmark, H.

    2012-12-01

    The role of ionization in the formation of clouds and aerosols has been debated for many years. A body of evidence exists that correlates cloud properties to galactic cosmic ray ionization; however these results are still contested. In recent years experimental evidence has also been produced showing that ionization can promote the nucleation of small aerosols at atmospheric conditions. The experiments showed that an increase in ionization leads to an increase in the formation of ultrafine aerosols (~3 nm), but in the real atmosphere such small particles have to grow by coagulation and condensation to become cloud condensation nuclei (CCN) in order to have an effect on clouds. However, numerical studies predict that variations in the count of ultra-fine aerosols will lead only to an insignificant change in the count of CCN. This is due to 1) the competition between the additional ultra-fine aerosols for the limited supply of condensable gases leading to a slower growth and 2) the increased loss rates of the additional particles during the longer growth-time. We investigated the growth of aerosols to CCN sizes using an 8 m3 reaction chamber made from electro-polished stainless steel. One side was fitted with a Teflon foil to allow ultraviolet light to illuminate the chamber, which was continuously flushed with dry purified air. Variable concentrations of water vapor, ozone, and sulfur dioxide could be added to the chamber. UV-lamps initiated photochemistry producing sulfuric acid. Ionization could be enhanced with two Cs-137 gamma sources (30 MBq), mounted on each side of the chamber. Figure 1 shows the evolution of the aerosols, following a nucleation event induced by the gamma sources. Previous to the event the aerosols were in steady state. Each curve represents a size bin: 3-10 nm (dark purple), 10-20 nm (purple), 20-30 nm (blue), 30-40 nm (light blue), 40-50 nm (green), 50-60 nm (yellow), and 60-68 nm (red). Black curves show a ~1 hour smoothing. The initial

  18. Dose--response of initial G2-chromatid breaks induced in normal human fibroblasts by heavy ions

    NASA Technical Reports Server (NTRS)

    Kawata, T.; Durante, M.; Furusawa, Y.; George, K.; Takai, N.; Wu, H.; Cucinotta, F. A.; Dicello, J. F. (Principal Investigator)

    2001-01-01

    PURPOSE: To investigate initial chromatid breaks in prematurely condensed G2 chromosomes following exposure to heavy ions of different LET. MATERIAL AND METHODS: Exponentially growing human fibroblast cells AG1522 were irradiated with gamma-rays, energetic carbon (13 keV/ microm, 80 keV/microm), silicon (55 keV/microm) and iron (140 keV/microm, 185keV/microm, 440keV/microm) ions. Chromosomes were prematurely condensed using calyculin-A. Initial chromatid-type and isochromatid breaks in G2 cells were scored. RESULTS: The dose response curves for total chromatid breaks were linear regardless of radiation type. The relative biological effectiveness (RBE) showed a LET-dependent increase, peaking around 2.7 at 55-80keV/microm and decreasing at higher LET. The dose response curves for isochromatid-type breaks were linear for high-LET radiations, but linear-quadratic for gamma-rays and 13 keV/microm carbon ions. The RBE for the induction of isochromatid breaks obtained from linear components increased rapidly between 13keV/microm (about 7) and 80keV/microm carbon (about 71), and decreased gradually until 440 keV/microm iron ions (about 66). CONCLUSIONS: High-LET radiations are more effective at inducing isochromatid breaks, while low-LET radiations are more effective at inducing chromatid-type breaks. The densely ionizing track structures of heavy ions and the proximity of sister chromatids in G2 cells result in an increase in isochromatid breaks.

  19. Ion thruster performance model

    NASA Technical Reports Server (NTRS)

    Brophy, J. R.

    1984-01-01

    A model of ion thruster performance is developed for high flux density, cusped magnetic field thruster designs. This model is formulated in terms of the average energy required to produce an ion in the discharge chamber plasma and the fraction of these ions that are extracted to form the beam. The direct loss of high energy (primary) electrons from the plasma to the anode is shown to have a major effect on thruster performance. The model provides simple algebraic equations enabling one to calculate the beam ion energy cost, the average discharge chamber plasma ion energy cost, the primary electron density, the primary-to-Maxwellian electron density ratio and the Maxwellian electron temperature. Experiments indicate that the model correctly predicts the variation in plasma ion energy cost for changes in propellant gas (Ar, Kr and Xe), grid transparency to neutral atoms, beam extraction area, discharge voltage, and discharge chamber wall temperature. The model and experiments indicate that thruster performance may be described in terms of only four thruster configuration dependent parameters and two operating parameters. The model also suggests that improved performance should be exhibited by thruster designs which extract a large fraction of the ions produced in the discharge chamber, which have good primary electron and neutral atom containment and which operate at high propellant flow rates.

  20. CFD Code Survey for Thrust Chamber Application

    NASA Technical Reports Server (NTRS)

    Gross, Klaus W.

    1990-01-01

    In the quest fo find analytical reference codes, responses from a questionnaire are presented which portray the current computational fluid dynamics (CFD) program status and capability at various organizations, characterizing liquid rocket thrust chamber flow fields. Sample cases are identified to examine the ability, operational condition, and accuracy of the codes. To select the best suited programs for accelerated improvements, evaluation criteria are being proposed.

  1. ION ACCELERATION SYSTEM

    DOEpatents

    Luce, J.S.; Martin, J.A.

    1960-02-23

    Well focused, intense ion beams are obtained by providing a multi- apertured source grid in front of an ion source chamber and an accelerating multi- apertured grid closely spaced from and in alignment with the source grid. The longest dimensions of the elongated apertures in the grids are normal to the direction of the magnetic field used with the device. Large ion currents may be withdrawn from the source, since they do not pass through any small focal region between the grids.

  2. Calibration of PICO Bubble Chamber Dark Matter Detectors

    NASA Astrophysics Data System (ADS)

    Jin, Miaotianzi; PICO Collaboration

    2016-03-01

    The PICO Collaboration builds bubble chambers for the direct detection of WIMP dark matter. I will present the suite of calibration experiments performed to measure the sensitivity of these chambers to nuclear recoils (the expected WIMP signal) and to gamma rays (a common background to the WIMP signal). These calibrations include measurements with a 10-ml C3F8 bubble chamber at Northwestern University and with a 30-ml C3F8 bubble chamber deployed in the University of Montreal's tandem Van de Graaf facility, giving the bubble chamber response to a variety of gamma rays, broad-spectrum neutron sources, and mono-energetic low energy neutrons. I will compare our measured sensitivities to those predicted by a simple thermodynamic model and will show how the results impact our ability to detect dark matter, with a focus on light WIMP searches. Supported by DOE Grant: DE-SC0012161.

  3. LRL 25-inch Bubble Chamber

    DOE R&D Accomplishments Database

    Alvarez, L. W.; Gow, J. D.; Barrera, F.; Eckman, G.; Shand, J.; Watt, R.; Norgren, D.; Hernandez, H. P.

    1964-07-08

    The recently completed 25-inch hydrogen bubble chamber combines excellent picture quality with a fast operating cycle. The chamber has a unique optical system and is designed to take several pictures each Bevatron pulse, in conjunction with the Bevatron rapid beam ejection system.

  4. Characterization of a Reverberation Chamber

    DTIC Science & Technology

    2015-10-01

    electromagnetic susceptibility and immunity of a device under test because of its repeatability and measurement speed. A reverberation chamber is...devices or unmanned aircraft systems has led to a baseline characterization of the reverberation chamber at the US Army Research Laboratory (ARL). A...

  5. Small rocket flowfield diagnostic chambers

    NASA Technical Reports Server (NTRS)

    Morren, Sybil; Reed, Brian

    1993-01-01

    Instrumented and optically-accessible rocket chambers are being developed to be used for diagnostics of small rocket (less than 440 N thrust level) flowfields. These chambers are being tested to gather local fluid dynamic and thermodynamic flowfield data over a range of test conditions. This flowfield database is being used to better understand mixing and heat transfer phenomena in small rockets, influence the numerical modeling of small rocket flowfields, and characterize small rocket components. The diagnostic chamber designs include: a chamber design for gathering wall temperature profiles to be used as boundary conditions in a finite element heat flux model; a chamber design for gathering inner wall temperature and static pressure profiles; and optically-accessible chamber designs, to be used with a suite of laser-based diagnostics for gathering local species concentration, temperature, density, and velocity profiles. These chambers were run with gaseous hydrogen/gaseous oxygen (GH2/GO2) propellants, while subsequent versions will be run on liquid oxygen/hydrocarbon (LOX/HC) propellants. The purpose, design, and initial test results of these small rocket flowfield diagnostic chambers are summarized.

  6. Anisotonic media and glutamate-induced ion transport and volume responses in primary astrocyte cultures.

    PubMed

    Kimelberg, H K

    1987-01-01

    1. The responses of primary monolayer astrocyte cultures prepared from neonatal rat brains to hyper- and hypotonic media and to the addition of L-glutamic acid were examined as part of a systematic approach to use these cultures to obtain information on the mechanisms of the volume changes seen in astroglial cells in situ. 2. Addition of 200 mM mannitol to the medium to make it hypertonic caused cell shrinkage as measured with [14C]3-O-methyl-D-glucose, and also activated K+ and Cl- uptake measured with 86Rb+ and 36Cl- respectively. The increased ion uptake was completely inhibited by 0.1 mM bumetanide, showing that the Na+ + K+ + 2 Cl- co-transport system was being activated by cell shrinkage. 3. Studies of 86Rb+ uptake as a function of external K+ and hypertonic media showed a complex pattern. Increased bumetanide-sensitive, hypertonic-stimulated uptake of 86Rb+ was seen up to 20 mM K+0, with maximum stimulation being first reached at around 2 to 5 mM K+. At concentrations greater than 20 mM K+0 there was a further increase in bumetanide-sensitive 86Rb+ uptake, but there was no stimulation of this uptake by hypertonicity. There were also increases in bumetanide-insensitive 86Rb+ fluxes at [K+]0 higher than 20 mM that may have been due to opening of voltage-dependent K+ channels; this increased 86Rb+ flux was decreased in hypertonic medium. 4. When primary astrocyte cultures were swollen in hypotonic medium there was a rapid increase in volume as measured with [14C] 3-O-methyl-D-glucose, which then decreased in the continued presence of hypotonic medium. Thus, these cells exhibit volume regulatory decrease or RVD, as described for other cells. The possible ionic bases of this phenomenon have not yet been fully examined but the initial RVD did not appear to stimulate a furosemide-sensitive cotransport system. 5. Glutamate has been implicated as a possible endogenous effector of volume change in astrocytes. In the presence of ouabain, L-glutamate led to swelling of

  7. Differential response of olfactory sensory neuron populations to copper ion exposure in zebrafish.

    PubMed

    Lazzari, Maurizio; Bettini, Simone; Milani, Liliana; Maurizii, Maria Gabriella; Franceschini, Valeria

    2017-02-01

    The peripheral olfactory system of fish is in direct contact with the external aqueous environment, so dissolved contaminants can easily impair sensory functions and cause neurobehavioral injuries. The olfactory epithelium of fish is arranged in lamellae forming a rosette in the olfactory cavity and contains three main types of olfactory sensory neurons (OSNs): ciliated (cOSNs) and microvillous olfactory sensory neurons (mOSNs), common to all vertebrates, and a third minor group of olfactory neurons, crypt cells, absent in tetrapods. Since copper is a ubiquitously diffusing olfactory toxicant and a spreading contaminant in urban runoff, we investigated the effect of low copper concentration on the three different OSNs in the olfactory epithelium of zebrafish, a model system widely used in biological research. Image analysis was applied for morphometry and quantification of immunohistochemically detected OSNs. Copper exposure resulted in an evident decrease in olfactory epithelium thickness. Moreover, after exposure, the lamellae of the dorsal and ventral halves of the olfactory rosettes showed a different increase in their sensory areas, suggesting a lateral migration of new cells into non-sensory regions. The results of the present study provide clear evidence of a differential response of the three neural cell populations of zebrafish olfactory mucosa after 96h of exposure to copper ions at the sublethal concentration of 30μgL(-1). Densitometric values of cONS, immunostained with anti-G αolf, decreased of about 60% compared to the control. When the fish were transferred to water without copper addition and examined after 3, 10 and 30days, we observed a partial restoration of anti-G αolf staining intensity to normal condition. The recovery of cOSNs appeared sustained by neuronal proliferation, quantified with anti-PCNA immunostaining, in particular in the early days after exposure. The densitometric analysis applied to mOSNs, immunostained with anti-TRPC2

  8. DUAL HEATED ION SOURCE STRUCTURE HAVING ARC SHIFTING MEANS

    DOEpatents

    Lawrence, E.O.

    1959-04-14

    An ion source is presented for calutrons, particularly an electrode arrangement for the ion generator of a calutron ion source. The ion source arc chamber is heated and an exit opening with thermally conductive plates defines the margins of the opening. These plates are electrically insulated from the body of the ion source and are connected to a suitable source of voltage to serve as electrodes for shaping the ion beam egressing from the arc chamber.

  9. National Ignition Facility Target Chamber

    SciTech Connect

    Wavrik, R W; Cox, J R; Fleming, P J

    2000-10-05

    On June 11, 1999 the Department of Energy dedicated the single largest piece of the National Ignition Facility (NIF) at Lawrence Livermore National Laboratory (LLNL) in Livermore, California. The ten (10) meter diameter aluminum target high vacuum chamber will serve as the working end of the largest laser in the world. The output of 192 laser beams will converge at the precise center of the chamber. The laser beams will enter the chamber in two by two arrays to illuminate 10 millimeter long gold cylinders called hohlraums enclosing 2 millimeter capsule containing deuterium, tritium and isotopes of hydrogen. The two isotopes will fuse, thereby creating temperatures and pressures resembling those found only inside stars and in detonated nuclear weapons, but on a minute scale. The NIF Project will serve as an essential facility to insure safety and reliability of our nation's nuclear arsenal as well as demonstrating inertial fusion's contribution to creating electrical power. The paper will discuss the requirements that had to be addressed during the design, fabrication and testing of the target chamber. A team from Sandia National Laboratories (SNL) and LLNL with input from industry performed the configuration and basic design of the target chamber. The method of fabrication and construction of the aluminum target chamber was devised by Pitt-Des Moines, Inc. (PDM). PDM also participated in the design of the chamber in areas such as the Target Chamber Realignment and Adjustment System, which would allow realignment of the sphere laser beams in the event of earth settlement or movement from a seismic event. During the fabrication of the target chamber the sphericity tolerances had to be addressed for the individual plates. Procedures were developed for forming, edge preparation and welding of individual plates. Construction plans were developed to allow the field construction of the target chamber to occur parallel to other NIF construction activities. This was

  10. Multiple ionization of neon atoms in collisions with bare and dressed ions: A mean-field description considering target response

    NASA Astrophysics Data System (ADS)

    Schenk, Gerald; Kirchner, Tom

    2015-05-01

    We investigate projectile-charge-state-differential electron removal from neon atoms by impact of He2+, Li3+, B2+, and C3+ ions at intermediate projectile energies (25 keV/u to 1 MeV/u ). The many-electron problem is described with an independent electron model in which active electrons at both collision centers are propagated in a common mean-field potential. Response to electron removal is taken into account in terms of a time-dependent screening potential, and a Slater-determinant-based method is used for the final-state analysis. Total cross sections for net recoil ion production, multiple ionization, and capture channels are mostly in good agreement with published experimental data. Results from equicharged bare and dressed ions are compared and the net recoil ion production cross section is broken down into contributions associated with different final projectile charge states in order to shed light on the role of the projectile electrons.

  11. Microstructural response of InGaN to swift heavy ion irradiation

    SciTech Connect

    Zhang, L. M.; Jiang, W.; Fadanelli, R. C.; Ai, W. S.; Peng, J. X.; Wang, T. S.; Zhang, C. H.

    2016-12-01

    A monocrystalline In0.18Ga0.82N film of ~275 nm in thickness grown on a GaN/Al2O3 substrate was irradiated with 290 MeV 238U32+ ions to a fluence of 1.2 x 12 cm-2 at room temperature. The irradiated sample was characterized using helium ion microscopy (HIM), Rutherford backscattering spectrometry under ion-channeling conditions (RBS/C), and high-resolution x-ray diffraction (HRXRD). The irradiation leads to formation of ion tracks throughout the thin In0.18Ga0.82N film and the 3.0 µm thick GaN buffer layer. The mean diameter of the tracks in In0.18Ga0.82N is ~9 nm, as determined by HIM examination. Combination of the HIM and RBS/C data suggests that the material in the track is likely to be highly disordered or fully amorphized, in contrast to a crystalline structure within the ion track in GaN. Lattice relaxation in In0.18Ga0.82N and a distribution of d-spacing of the (0002) planes in GaN with lattice expansion are observed after irradiation.

  12. Dose response and mutation induction by ion beam irradiation in buckwheat

    NASA Astrophysics Data System (ADS)

    Morishita, T.; Yamaguchi, H.; Degi, K.; Shikazono, N.; Hase, Y.; Tanaka, A.; Abe, T.

    2003-05-01

    The biological effects of ion beams were investigated to pursue the development of a method for breeding by mutation in buckwheat. Common buckwheat (Botansoba, Bot) and tartary buckwheat (Rotundatiem, Rot) seeds were exposed to various ions in linear energy transfer (LET) at 9-630 keV/μm. The lethal dose 50 (LD 50) of ion beams were 10-300 Gy (Bot) and 30-500 Gy (Rot). It was indicated that a penetrating depth in excess of 1.7 mm is necessary to thoroughly saturate the target, and ions with a penetrating depth of less than 2.2 mm were affected by the presence of hulls. The maximum values of the relative biological effectiveness were 17.7 (Rot) and 22.5 (Bot) at 305 keV/μm. The effective cross sections increased with the LET, and the maximum values were 2.7 (Rot) and 3.0 μm 2 (Bot). The mutation induction effects of He and C ions were higher than those of gamma rays.

  13. Comparison of the Effects of Carbon Ion and Photon Irradiation on the Angiogenic Response in Human Lung Adenocarcinoma Cells

    SciTech Connect

    Kamlah, Florentine; Haenze, Joerg; Arenz, Andrea; Seay, Ulrike; Hasan, Diya; Gottschald, Oana R.; Seeger, Werner; Rose, Frank

    2011-08-01

    Purpose: Radiotherapy resistance is a commonly encountered problem in cancer treatment. In this regard, stabilization of endothelial cells and release of angiogenic factors by cancer cells contribute to this problem. In this study, we used human lung adenocarcinoma (A549) cells to compare the effects of carbon ion and X-ray irradiation on the cells' angiogenic response. Methods and Materials: A549 cells were irradiated with biologically equivalent doses for cell survival of either carbon ions (linear energy transfer, 170 keV/{mu}m; energy of 9.8 MeV/u on target) or X-rays and injected with basement membrane matrix into BALB/c nu/nu mice to generate a plug, allowing quantification of angiogenesis by blood vessel enumeration. The expression of angiogenic factors (VEGF, PlGF, SDF-1, and SCF) was assessed at the mRNA and secreted protein levels by using real-time reverse transcription-PCR and enzyme-linked immunosorbent assay. Signal transduction mediated by stem cell factor (SCF) was assessed by phosphorylation of its receptor c-Kit. For inhibition of SCF/c-Kit signaling, a specific SCF/c-Kit inhibitor (ISCK03) was used. Results: Irradiation of A549 cells with X-rays (6 Gy) but not carbon ions (2 Gy) resulted in a significant increase in blood vessel density (control, 20.71 {+-} 1.55; X-ray, 36.44 {+-} 3.44; carbon ion, 16.33 {+-} 1.03; number per microscopic field). Concordantly, irradiation with X-rays but not with carbon ions increased the expression of SCF and subsequently caused phosphorylation of c-Kit in endothelial cells. ISCK03 treatment of A549 cells irradiated with X-rays (6 Gy) resulted in a significant decrease in blood vessel density (X-ray, 36.44 {+-} 3.44; X-ray and ISCK03, 4.33 {+-} 0.71; number of microscopic field). These data indicate that irradiation of A549 cells with X-rays but not with carbon ions promotes angiogenesis. Conclusions: The present study provides evidence that SCF is an X-ray-induced mediator of angiogenesis in A549 cells, a

  14. Transparent aluminium nanowire electrodes with optical and electrical anisotropic response fabricated by defocused ion beam sputtering

    NASA Astrophysics Data System (ADS)

    Repetto, Diego; Giordano, Maria Caterina; Martella, Christian; Buatier de Mongeot, Francesco

    2015-02-01

    Self-organized Al nanowire (NW) electrodes have been obtained by defocused Ion Beam Sputtering (IBS) of polycrystalline Al films grown by sputter deposition. The electrical sheet resistance of the electrode has been acquired in situ during ion bombardment of the samples, evidencing an increase of the electronic transport anisotropy as a function of ion fluence between the two directions parallel and orthogonal to the NWs axis. Optical spectra in transmission also show a large dichroism between the two directions, suggesting the role of localized plasmons in the UV spectral range. The results show that Al NW electrodes, prepared under experimental conditions which are compatible with those of conventional industrial coaters and implanters, could represent a low cost alternative to the transparent conductive oxides employed in optoelectronic devices.

  15. Modified agricultural waste biomass with enhanced responsive properties for metal-ion remediation: a green approach

    NASA Astrophysics Data System (ADS)

    Mahajan, Garima; Sud, Dhiraj

    2012-12-01

    Dalbergia sissoo pods, a lignocellulosic nitrogenous waste biomass, was evaluated for sequestering of Cr(VI) from synthetic wastewater. Dalbergia sissoo pods (DSP) were used in three different forms, viz. natural (DSPN), impregnated in the form of hydrated beads (DSPB), and in carbonized form (DSPC) for comparative studies. Batch experiments were performed for the removal of hexavalent chromium. Effects of pH adsorbent dose, initial metal-ion concentration, stirring speed, and contact time were investigated. The removal of metal ions was dependent on the physico-chemical characteristics of the adsorbent, adsorbate concentration, and other studied process parameters. Maximum metal removal for Cr(VI) was observed at pH 2.0. The experimental data were analyzed based on Freundlich and Langmuir adsorption isotherms. Kinetic studies indicated that the adsorption of metal ions followed a pseudo-second-order equation.

  16. ION PRODUCING MECHANISM

    DOEpatents

    Backus, J.G.

    1958-08-19

    A novel ion source is described for use in a calutron which has the prime adwantage of reducing the nunnber of unwanted ions in the ion generating mechamism.An important feature of the invention resides In an arc chamber having a lining of the polyisotopic material to be treated In the calutron and bombardment of the linirg with positive ions of a light gas to induce sputtering and ionization of the lining. With the reduction of unwanted ions in the source beam provided by the described source, the calutron operation may be more accurately controlled.

  17. PULSED ION SOURCE

    DOEpatents

    Anderson, C.E.; Ehlers, K.W.

    1958-06-17

    An ion source is described for producing very short high density pulses of ions without bcam scattering. The ions are created by an oscillating electron discharge within a magnetic field. After the ions are drawn from the ionization chamber by an accelerating electrode the ion beam is under the influence of the magnetic field for separation of the ions according to mass and, at the same time, passes between two neutralizing plntes maintained nt equal negative potentials. As the plates are formed of a material having a high ratio of secondary electrons to impinging ions, the ion bombardment of the plntes emits electrons which neutralize the frirge space-charge of the beam and tend to prevent widening of the beam cross section due to the mutual repulsion of the ions.

  18. Roos and NACP-02 ion chamber perturbations and water-air stopping-power ratios for clinical electron beams for energies from 4 to 22 MeV

    NASA Astrophysics Data System (ADS)

    Bailey, M.; Shipley, D. R.; Manning, J. W.

    2015-02-01

    Empirical fits are developed for depth-compensated wall- and cavity-replacement perturbations in the PTW Roos 34001 and IBA / Scanditronix NACP-02 parallel-plate ionisation chambers, for electron beam qualities from 4 to 22 MeV for depths up to approximately 1.1 × R50,D. These are based on calculations using the Monte Carlo radiation transport code EGSnrc and its user codes with a full simulation of the linac treatment head modelled using BEAMnrc. These fits are used with calculated restricted stopping-power ratios between air and water to match measured depth-dose distributions in water from an Elekta Synergy clinical linear accelerator at the UK National Physical Laboratory. Results compare well with those from recent publications and from the IPEM 2003 electron beam radiotherapy Code of Practice.

  19. Kinetic response of ionospheric ions to onset of auroral electric fields

    NASA Technical Reports Server (NTRS)

    Chiu, Y. T.; Kan, J. R.

    1981-01-01

    Examination of the exact analytic solution of a kinetic model of collisional interaction of ionospheric fions with atmospheric neutrals in the Bhatnagar-Gross-Krook approximation, shows that the onset of intense auroral electric fields in the topside ionosphere can produce the following kinetic effects: (1) heat the bulk ionospheric ions to approximately 2 eV, thus driving them up to higher altitudes where they can be subjected to collisionless plasma processes; (2) produce a nonMaxwellian superthermal tail in the distribution function; and (3) cause the ion distribution function to be anisotropic with respect to the magnetic field with the perpendicular average thermal energy exceeding the parallel thermal energy.

  20. Experimental investigation of the effect of polymer matrices on polymer fibre optic oxygen sensors and their time response characteristics using a vacuum testing chamber and a liquid flow apparatus.

    PubMed

    Chen, Rongsheng; Formenti, Federico; McPeak, Hanne; Obeid, Andrew N; Hahn, Clive; Farmery, Andrew

    2016-01-01

    Very fast sensors that are able to track rapid changes in oxygen partial pressure (PO2) in the gas and liquid phases are increasingly required in scientific research - particularly in the life sciences. Recent interest in monitoring very fast changes in the PO2 of arterial blood in some respiratory failure conditions is one such example. Previous attempts to design fast intravascular electrochemical oxygen sensors for use in physiology and medicine have failed to meet the criteria that are now required in modern investigations. However, miniature photonic devices are capable of meeting this need. In this article, we present an inexpensive polymer type fibre-optic, oxygen sensor that is two orders of magnitude faster than conventional electrochemical oxygen sensors. It is constructed with biologically inert polymer materials and is both sufficiently small and robust for direct insertion in to a human artery. The sensors were tested and evaluated in both a gas testing chamber and in a flowing liquid test system. The results showed a very fast T90 response time, typically circa 20 ms when tested in the gas phase, and circa 100 ms in flowing liquid.

  1. Experimental investigation of the effect of polymer matrices on polymer fibre optic oxygen sensors and their time response characteristics using a vacuum testing chamber and a liquid flow apparatus

    PubMed Central

    Chen, Rongsheng; Formenti, Federico; McPeak, Hanne; Obeid, Andrew N.; Hahn, Clive; Farmery, Andrew

    2016-01-01

    Very fast sensors that are able to track rapid changes in oxygen partial pressure (PO2) in the gas and liquid phases are increasingly required in scientific research – particularly in the life sciences. Recent interest in monitoring very fast changes in the PO2 of arterial blood in some respiratory failure conditions is one such example. Previous attempts to design fast intravascular electrochemical oxygen sensors for use in physiology and medicine have failed to meet the criteria that are now required in modern investigations. However, miniature photonic devices are capable of meeting this need. In this article, we present an inexpensive polymer type fibre-optic, oxygen sensor that is two orders of magnitude faster than conventional electrochemical oxygen sensors. It is constructed with biologically inert polymer materials and is both sufficiently small and robust for direct insertion in to a human artery. The sensors were tested and evaluated in both a gas testing chamber and in a flowing liquid test system. The results showed a very fast T90 response time, typically circa 20 ms when tested in the gas phase, and circa 100 ms in flowing liquid. PMID:26726286

  2. The high momentum spectrometer drift chambers

    NASA Astrophysics Data System (ADS)

    Abbott, D.; Baker, O. K.; Beaufait, J.; Bennett, C.; Bryant, E.; Carlini, R.; Kross, B.; McCauley, A.; Naing, W.; Shin, T.; Vulcan, W.

    1992-12-01

    The High Momentum Spectrometer in Hall C will use planar drift chambers for charged particle track reconstruction. The chambers are constructed using well understood technology and a conventional gas mixture. Two (plus one spare) drift chambers will be constructed for this spectrometers. Each chamber will contain 6 planes of readout channels. This paper describes the chamber design and gas handling system used.

  3. Modeling, Calibration, and Verification of a Fission Chamber for ACRR Experimentersa

    NASA Astrophysics Data System (ADS)

    Coburn, Jonathan; Luker, S. Michael; Parma, Edward J.; DePriest, K. Russell

    2016-02-01

    When performing research at a reactor facility, experimenters often need to determine the neutron fluence achieved during an operation. Facilities typically provide guidance in the form of neutron fluence per megajoule (MJ) or through passive dosimetry results. After experiment completion, there is sometimes a delay of several days (or weeks) before the passive dosimetry results are available. In the interim, an experimenter does not have confirmation that the desired irradiation levels were reached. Active dosimetry may provide an estimate of neutron fluxes, but few active detectors are available that have been calibrated to measure neutron fluxes obtained inside the Annular Core Research Reactor (ACRR) central cavity environment. For past experiments at the ACRR, the neutron fluence was calculated by integrating the response of a fission chamber rate detection signal and then normalizing this integral to fluence determined from passive dosimetry. An alternative method of directly measuring neutron flux is desired; the new methodology described provides a complete neutron flux profile after a reactor pulse, utilizing fission chamber physics in combination with a compensating ion chamber to extract and convert a current signal to neutron flux as a function of time. Work supported by the United States Department of Energy at Sandia National Laboratories. Sandia National Laboratories is a multi-program laboratory managed and operated by Sandia Corporation, a wholly owned subsidiary of Lockheed Martin Corporation, for the U.S. Department of Energy's National Nuclear Security Administration under contract DE-AC04-94AL85000.

  4. Microstructural response of InGaN to swift heavy ion irradiation

    NASA Astrophysics Data System (ADS)

    Zhang, L. M.; Jiang, W.; Fadanelli, R. C.; Ai, W. S.; Peng, J. X.; Wang, T. S.; Zhang, C. H.

    2016-12-01

    A monocrystalline In0.18Ga0.82N film of ∼275 nm in thickness grown on a GaN/Al2O3 substrate was irradiated with 290 MeV 238U32+ ions to a fluence of 1.2 × 1012 cm-2 at room temperature. The irradiated sample was characterized using helium ion microscopy (HIM), Rutherford backscattering spectrometry under ion-channeling conditions (RBS/C), and high-resolution X-ray diffraction (HRXRD). The irradiation leads to formation of ion tracks throughout the thin In0.18Ga0.82N film and the 3.0 μm thick GaN buffer layer. The mean diameter of the tracks in In0.18Ga0.82N is ∼9 nm, as determined by HIM examination. Combination of the HIM and RBS/C data suggests that the In0.18Ga0.82N material in the track is likely to be highly disordered or fully amorphized. The irradiation induced lattice relaxation in In0.18Ga0.82N and a distribution of d-spacing of the (0 0 0 2) planes in GaN with lattice expansion are observed by HRXRD.

  5. A metal–ion-responsive adhesive material via switching of molecular recognition properties

    PubMed Central

    Nakamura, Takashi; Takashima, Yoshinori; Hashidzume, Akihito; Yamaguchi, Hiroyasu; Harada, Akira

    2014-01-01

    Common adhesives stick to a wide range of materials immediately after they are applied to the surfaces. To prevent indiscriminate sticking, smart adhesive materials that adhere to a specific target surface only under particular conditions are desired. Here we report a polymer hydrogel modified with both β-cyclodextrin (βCD) and 2,2′-bipyridyl (bpy) moieties (βCD–bpy gel) as a functional adhesive material responding to metal ions as chemical stimuli. The adhesive property of βCD–bpy gel based on interfacial molecular recognition is expressed by complexation of metal ions to bpy that controlled dissociation of supramolecular cross-linking of βCD–bpy. Moreover, adhesion of βCD–bpy gel exhibits selectivity on the kinds of metal ions, depending on the efficiency of metal–bpy complexes in cross-linking. Transduction of two independent chemical signals (metal ions and host–guest interactions) is achieved in this adhesion system, which leads to the development of highly orthogonal macroscopic joining of multiple objects. PMID:25099995

  6. ECR ion source with electron gun

    DOEpatents

    Xie, Z.Q.; Lyneis, C.M.

    1993-10-26

    An Advanced Electron Cyclotron Resonance ion source having an electron gun for introducing electrons into the plasma chamber of the ion source is described. The ion source has a injection enclosure and a plasma chamber tank. The plasma chamber is defined by a plurality of longitudinal magnets. The electron gun injects electrons axially into the plasma chamber such that ionization within the plasma chamber occurs in the presence of the additional electrons produced by the electron gun. The electron gun has a cathode for emitting electrons therefrom which is heated by current supplied from an AC power supply while bias potential is provided by a bias power supply. A concentric inner conductor and outer conductor carry heating current to a carbon chuck and carbon pusher which hold the cathode in place and also heat the cathode. In the Advanced Electron Cyclotron Resonance ion source, the electron gun replaces the conventional first stage used in prior electron cyclotron resonance ion generators. 5 figures.

  7. A high rate proportional chamber

    SciTech Connect

    Henderson, R.; Fraszer, W.; Openshaw, R.; Sheffer, G.; Salomon, M.; Dew, S.; Marans, J.; Wilson, P.

    1987-02-01

    Gas mixtures with high specific ionization allow the use of small interelectrode distances while still maintaining full efficiency. With the short electron drift distances the timing resolution is also improved. The authors have built and operated two 25 cm/sup 2/ chambers with small interelectrode distances. Also single wire detector cells have been built to test gas mixture lifetimes. Various admixtures of CF/sub 4/, DME, Isobutane, Ethane and Argon have been tested. Possible applications of such chambers are as beam profile monitors, position tagging of rare events and front end chambers in spectrometers.

  8. Study of the PTW microLion chamber temperature dependence

    NASA Astrophysics Data System (ADS)

    Gómez, F.; González-Castaño, D.; Díaz-Botana, P.; Pardo-Montero, J.

    2014-06-01

    The use of liquid ionization chambers in radiotherapy has grown during the past few years. While for air ionization chambers the kTP correction for air mass density due to pressure and temperature variations is well known, less work has been done on the case of liquid ionization chambers, where there is still the need to take into account the influence of temperature in the free ion yield. We have measured the PTW microLion isooctane-filled ionization chamber temperature dependence in a ˜ ±10 °C interval around the standard 20 °C room temperature for three operation voltages, including the manufacturer recommended voltage, and two beam qualities, 60Co and 50 kV x-rays. Within the measured temperature range, the microLion signal exhibits a positive linear dependence, which is around 0.24% K-1 at 800 V with 60Co irradiation. This effect is of the same order of magnitude as the T dependence found in air ionization chambers, but its nature is completely different and its sign opposite to that of an air chamber. Onsager theory has been used to model the results and is consistent with this linear behaviour. However, some inconsistencies in the modelling of the 50 kV x-ray results have been found that are attributed to the failure of Onsager's isolated pair assumption for such radiation quality.

  9. Advanced ion thruster research

    NASA Technical Reports Server (NTRS)

    Wilbur, P. J.

    1984-01-01

    A simple model describing the discharge chamber performance of high strength, cusped magnetic field ion thrusters is developed. The model is formulated in terms of the energy cost of producing ions in the discharge chamber and the fraction of ions produced in the discharge chamber that are extracted to form the ion beam. The accuracy of the model is verified experimentally in a series of tests wherein the discharge voltage, propellant, grid transparency to neutral atoms, beam diameter and discharge chamber wall temperature are varied. The model is exercised to demonstrate what variations in performance might be expected by varying discharge chamber parameters. The results of a study of xenon and argon orificed hollow cathodes are reported. These results suggest that a hollow cathode model developed from research conducted on mercury cathodes can also be applied to xenon and argon. Primary electron mean free paths observed in argon and xenon cathodes that are larger than those found in mercury cathodes are identified as a cause of performance differences between mercury and inert gas cathodes. Data required as inputs to the inert gas cathode model are presented so it can be used as an aid in cathode design.

  10. Subscale LOX/hydrogen testing with a modular chamber and a swirl coaxial injector

    NASA Technical Reports Server (NTRS)

    Elam, Sandra K.

    1991-01-01

    To support basic injector and chamber technology, the response of a modular calorimeter chamber to an injector with swirl coaxial elements was investigated. The tests supported both the Advanced Launch System (ALS) and the Space Shuttle Main Engine programs. Original test plans included chamber pressures up to 2250 psia, the current ALS engine criteria, but hardware limitations forced conditions to be reduced. With four different chamber configurations, a variety of data was obtained with chamber pressures ranging from 1483 psia to 1679 psia and mixture ratios from 5.24 to 6.90. The swirl coaxial injector showed good chamber wall compatibility, despite misaligned elements, and its high performance was independent of fuel. Heating rates and wall temperatures were acceptable and close to predict profiles, and after scaling to a chamber pressure of 2250 psia, heating rates remained acceptable. In addition, a chamber spool made with the vacuum plasma spray process survived hot-fire testing with no detrimental effects.

  11. Ionization chamber gradient effects in nonstandard beam configurations

    SciTech Connect

    Bouchard, Hugo; Seuntjens, Jan; Carrier, Jean-Francois; Kawrakow, Iwan

    2009-10-15

    Purpose: For the purpose of nonstandard beam reference dosimetry, the current concept of reporting absorbed dose at a point in water located at a representative position in the chamber volume is investigated in detail. As new nonstandard beam reference dosimetry protocols are under development, an evaluation of the role played by the definition of point of measurement could lead to conceptual improvements prior to establishing measurement procedures. Methods: The present study uses the current definition of reporting absorbed dose to calculate ionization chamber perturbation factors for two cylindrical chamber models (Exradin A12 and A14) using the Monte Carlo method. The EGSnrc based user-code EGS lowbar chamber is used to calculate chamber dose responses of 14 IMRT beams chosen to cause considerable dose gradients over the chamber volume as previously used by Bouchard and Seuntjens [''Ionization chamber-based reference dosimetry of intensity modulated radiation beams,'' Med. Phys. 31(9), 2454-5465 (2004)]. Results: The study shows conclusively the relative importance of each physical effect involved in the nonstandard beam correction factors of 14 IMRT beams. Of all correction factors involved in the dosimetry of the beams studied, the gradient perturbation correction factor has the highest magnitude, on average, 11% higher compared to reference conditions for the Exradin A12 chamber and about 5% higher for the Extradin A14 chamber. Other perturbation correction factors (i.e., P{sub wall}, P{sub stem}, and P{sub cel}) are, on average, less than 0.8% different from reference conditions for the chambers and beams studied. The current approach of reporting measured absorbed dose at a point in water coinciding with the location of the centroid of the chamber is the main factor responsible for large correction factors in nonstandard beam deliveries (e.g., intensity modulated radiation therapy) reported in literature. Conclusions: To reduce or eliminate the magnitude

  12. Characterization of hollow cathode, ring cusp discharge chambers. M.S. Thesis

    NASA Technical Reports Server (NTRS)

    Vaughn, Jason A.

    1989-01-01

    An experimental study into the effects of changes in such physical design parameters as hollow cathode position, anode position and ring cusp magnetic field configuration and strength on discharge chamber performance, is described. The results are presented in terms of comparative plasma ion energy cost, extracted ion fraction and ion beam profile data. Such comparisons are used to demonstrate specific means by which changes in these design parameters induce changes in performance, i.e., through changes in the loss rates of primary electrons to the anode, of ions to discharge chamber walls or of ions to cathode and anode surfaces. Results show: (1) the rate of primary electron loss to the anode decreases as the anode is moved downstream of the ring cusp toward the screen grid, (2) the loss rate of ions to hollow cathode surfaces are excessive if the cathode is located upstream of a point of peak magnetic flux density on the discharge chamber centerline, and (3) the fraction of the ions produced that are lost to discharge chamber walls and ring magnet surfaces is reduced by positioning the magnet rings so the plasma density is uniform over the grid surface and so there are no steep magnetic flux density gradients near the walls through which ions can be lost by Bohm diffusion. The uniformity of the plasma density at the grids can also be improved by moving the point of primary electron injection into the discharge chamber off of the chamber centerline. Other results show the discharge chamber losses decrease when a filament cathode is substituted for a hollow cathode to the extent of the hollow cathode operating power. When plasma ion energy cost is determined in such a way that the cost of operating the hollow cathode is subtracted out, the performance using either electron source is similar.

  13. Ionospheric plasma outflow in response to transverse ion heating: Self-consistent macroscopic treatment

    NASA Technical Reports Server (NTRS)

    Singh, N.

    1994-01-01

    We examined the various likely processes for creating the cavities and found that the mirror force acting on the transversely heated ions is the most likely mechanism. The pondermotive force causing the wave collapse was found to be a much weaker force than the mirror force on the transversely heated ions observed inside the cavities along with the lower hybrid waves. Using a hydrodynamic model for the polar wind we modeled the cavity formation and found that for the heating rate obtained from the observed waves, the mirror force does create cavities with depletions as observed. Some initial results from this study were published in a recent Geophysical Research Letters and were reported in the Fall AGU meeting in San Francisco. We have continued this investigation using a large-scale semikinetic model.

  14. Optimization of magneto-resistive response of ion-irradiated exchange biased films through zigzag arrangement of magnetization

    SciTech Connect

    Trützschler, Julia; Sentosun, Kadir; McCord, Jeffrey; Langer, Manuel; Fassbender, Jürgen; Mönch, Ingolf; Mattheis, Roland

    2014-03-14

    Exchange coupled ferromagnetic-antiferromagnetic Ni{sub 81}Fe{sub 19}/Ir{sub 23}Mn{sub 77} films with a zigzag alignment of magnetization are prepared by local ion irradiation. The anisotropic magneto-resistive behavior of the magnetic thin film structures is correlated to the magnetic structure and modeled. A unique uniaxial field sensitivity along the net magnetization alignment is obtained through the orthogonally modulated and magnetic domain wall stabilized magnetic ground state. Controlling local thin film magnetization distributions and, thus, the overall magnetization response opens unique ways to tailor the magneto-resistive sensitivity of functional magnetic thin film devices.

  15. A micro-gap, air-filled ionisation chamber as a detector for criticality accident dosimetry.

    PubMed

    Murawski, Ł; Zielczyński, M; Golnik, N; Gryziński, M A

    2014-10-01

    A micro-gap air-filled ionisation chamber was designed for criticality dosimetry. The special feature of the chamber is its very small gap between electrodes of only 0.3 mm. This prevents ion recombination at high dose rates and minimises the influence of gas on secondary particles spectrum. The electrodes are made of polypropylene because of higher content of hydrogen in this material, when compared with soft tissue. The difference between neutron and gamma sensitivity in such chamber becomes practically negligible. The chamber's envelope contains two specially connected capacitors, one for polarising the electrodes and the other for collecting the ionisation charge.

  16. IRIS Leaves Thermal Vacuum Chamber

    NASA Video Gallery

    This video shows the transportation of the IRIS observatory from the thermal vacuum chamber back to the clean tent for final testing and preparations for delivery to the launch site at Vandenberg A...

  17. Vaporization chambers and associated methods

    DOEpatents

    Turner, Terry D.; Wilding, Bruce M.; McKellar, Michael G.; Shunn, Lee P.

    2017-02-21

    A vaporization chamber may include at least one conduit and a shell. The at least one conduit may have an inlet at a first end, an outlet at a second end and a flow path therebetween. The shell may surround a portion of each conduit and define a chamber surrounding the portion of each conduit. Additionally, a plurality of discrete apertures may be positioned at longitudinal intervals in a wall of each conduit, each discrete aperture of the plurality of discrete apertures sized and configured to direct a jet of fluid into each conduit from the chamber. A liquid may be vaporized by directing a first fluid comprising a liquid into the inlet at the first end of each conduit, directing jets of a second fluid into each conduit from the chamber through discrete apertures in a wall of each conduit and transferring heat from the second fluid to the first fluid.

  18. The multigap resistive plate chamber

    SciTech Connect

    Zeballos, E. Cerron; Crotty, I.; Hatzifotiadou, D.; Valverde, J. Lamas; Neupane, S.; Williams, M. C. S.; Zichichi, A.

    2015-02-03

    The paper describes the multigap resistive plate chamber (RPC). This is a variant of the wide gap RPC. However it has much improved time resolution, while keeping all the other advantages of the wide gap RPC design.

  19. Cyclically controlled welding purge chamber

    NASA Technical Reports Server (NTRS)

    Gallagher, Robert L. (Inventor)

    1996-01-01

    An arrangement for butt-welding cylindrical sections of large, thin-wall tanks includes a rotatable mandrel with side-by-side sets of radial position adjusters. Each set of adjusters bears on one of the tank sections adjacent the seam, to prevent the sections from sagging out-of-round. The mandrel rotates relative to the welder, so that a continuous seam is formed. A purge chamber is fixed in position behind the seam at the weld head, and is flushed with inert gas. The purge chamber includes a two-sided structure which is contiguous with the cylindrical sections and a circumferential vane to form an open-ended tube-like structure, through which the radial position adjusters pass as the mandrel and cylindrical workpiece sections rotate. The tube-like structure is formed into a chamber by a plurality of movable gates which are controlled to maintain a seal while allowing adjusters to progress through the purge chamber.

  20. Light diffusing fiber optic chamber

    DOEpatents

    Maitland, Duncan J.

    2002-01-01

    A light diffusion system for transmitting light to a target area. The light is transmitted in a direction from a proximal end to a distal end by an optical fiber. A diffusing chamber is operatively connected to the optical fiber for transmitting the light from the proximal end to the distal end and transmitting said light to said target area. A plug is operatively connected to the diffusing chamber for increasing the light that is transmitted to the target area.

  1. CALUTRON ION SOURCE

    DOEpatents

    Lofgren, E.J.

    1959-02-17

    An improvement is described in ion source mechanisms whereby the source structure is better adapted to withstanid the ravages of heat, erosion, and deterioration concomitant with operation of an ion source of the calutron type. A pair of molybdenum plates define the exit opening of the arc chamber and are in thermal contact with the walls of the chamber. These plates are maintained at a reduced temperature by a pair of copper blocks in thermal conducting contact therewith to form subsequent diverging margins for the exit opening.

  2. Advanced penning ion source

    DOEpatents

    Schenkel, Thomas; Ji, Qing; Persaud, Arun; Sy, Amy V.

    2016-11-01

    This disclosure provides systems, methods, and apparatus for ion generation. In one aspect, an apparatus includes an anode, a first cathode, a second cathode, and a plurality of cusp magnets. The anode has a first open end and a second open end. The first cathode is associated with the first open end of the anode. The second cathode is associated with the second open end of the anode. The anode, the first cathode, and the second cathode define a chamber. The second cathode has an open region configured for the passage of ions from the chamber. Each cusp magnet of the plurality of cusp magnets is disposed along a length of the anode.

  3. ION PRODUCING MECHANISM

    DOEpatents

    Backus, J.G.

    1958-09-01

    This patent relates to improvements in calutron devices and particularly describes a novel ion source. The unique feature of this source lies in the shaping of the ionizing electron stream to conform to the arc plasma boundary at the exit slit of the ionization chamber, thereby increasing the ion density produced at the plasma boundary. The particular structure consists of an electron source disposed at onc end of an elongated ionization chambcr and a coilimating electrode positioned to trim the electron stream to a crescent shape before entering the ionization chamber.

  4. Modeling of thorium (IV) ions adsorption onto a novel adsorbent material silicon dioxide nano-balls using response surface methodology.

    PubMed

    Kaynar, Ümit H; Şabikoğlu, Israfil; Kaynar, Sermin Çam; Eral, Meral

    2016-09-01

    The silicon dioxide nano-balls (nano-SiO2) were prepared for the adsorption of thorium (IV) ions from aqueous solution. The synthesized silicon dioxide nano-balls were characterized by Scanning Electron Microscopy/Energy Dispersive X-ray, X-ray Diffraction, Fourier Transform Infrared and BET surface area measurement spectroscopy. The effects of pH, concentration, temperature and the solid-liquid ratio on the adsorption of thorium by nano-balls were optimized using central composite design of response surface methodology. The interaction between four variables was studied and modelled. Furthermore, the statistical analysis of the results was done. Analysis of variance revealed that all of the single effects found statistically significant on the sorption of Th(IV). Probability F-values (F=4.64-14) and correlation coefficients (R(2)=0.99 for Th(IV)) indicate that model fit the experimental data well. The ability of this material to remove Th(IV) from aqueous solution was characterized by Langmuir, Freunlinch and Temkin adsorption isotherms. The adsorption capacity of thorium (IV) achieved 188.2mgg(-1). Thermodynamic parameters were determined and discussed. The batch adsorption condition with respect to interfering ions was tested. The results indicated that silicon dioxide nano-balls were suitable as sorbent material for adsorption and recovery of Th(IV) ions from aqueous solutions.

  5. Effect of structure and thermodynamic stability on the response of lanthanide stannate pyrochlores to ion beam irradiation.

    PubMed

    Lian, J; Helean, K B; Kennedy, B J; Wang, L M; Navrotsky, A; Ewing, R C

    2006-02-09

    The lanthanide stannates, Ln2Sn2O7, Ln=La-Lu and Y, have the isometric pyrochlore structure, A2B2O7, and their structural properties have been refined by Rietveld analysis of powder neutron and synchrotron X-ray diffraction data. In this study, the enthalpies of formation of selected stannate pyrochlores, Ln=La, Nd, Sm, Eu, Dy, and Yb, were measured by high-temperature oxide melt solution calorimetry. Their radiation response was determined by 1 MeV Kr2+ ion irradiation combined with in situ TEM observation over the temperature range of 25 to 1000 K. The enthalpy of formation from binary oxides of stannate pyrochlores became more endothermic (from -145 to -40 kJ/mol) as the size of the lanthanide in the A-site decreases. A more exothermic trend of the enthalpy of formation was observed in stannate pyrochlores with larger lanthanide ions, particularly La, possibly as a result of increased covalency in the Sn-O bond. In contrast to lanthanide titanate pyrochlores, Ln2Ti2O7, that are generally susceptible to radiation-induced amorphization and zirconate pyrochlores, Ln2Zr2O7, that are generally resistant to radiation-induced amorphization, the lanthanide stannate pyrochlores show a much greater variation in their response to ion irradiation. La, Nd, and Gd stannates experience the radiation-induced transformation to the aperiodic state, and the critical amorphization temperatures are approximately 960, 700, and 350 K, respectively. Y and Er stannate pyrochlores cannot be amorphized by ion beam irradiation, even at 25 K, and instead disorder to a defect fluorite structure. Comparison of the calorimetric and ion irradiation data for titanate, zirconate, and stannate pyrochlores reveals a strong correlation among subtle changes in crystal structure with changing composition, the energetics of the disordering process, and the temperature above which the material can no longer be amorphized. In summary, as the structure approaches the ideal, ordered pyrochlore structure

  6. Low frequency noise and radiation response in the partially depleted SOI MOSFETs with ion implanted buried oxide

    NASA Astrophysics Data System (ADS)

    Liu, Yuan; Chen, Hai-Bo; Liu, Yu-Rong; Wang, Xin; En, Yun-Fei; Li, Bin; Lu, Yu-Dong

    2015-08-01

    Low frequency noise behaviors of partially depleted silicon-on-insulator (PDSOI) n-channel metal-oxide semiconductors (MOS) transistors with and without ion implantation into the buried oxide are investigated in this paper. Owing to ion implantation-induced electron traps in the buried oxide and back interface states, back gate threshold voltage increases from 44.48 V to 51.47 V and sub-threshold swing increases from 2.47 V/dec to 3.37 V/dec, while electron field effect mobility decreases from 475.44 cm2/V·s to 363.65 cm2/V·s. In addition, the magnitude of normalized low frequency noise also greatly increases, which indicates that the intrinsic electronic performances are degenerated after ion implantation processing. According to carrier number fluctuation theory, the extracted flat-band voltage noise power spectral densities in the PDSOI devices with and without ion implantation are equal to 7×10-10 V2·Hz-1 and 2.7×10-8 V2·Hz-1, respectively, while the extracted average trap density in the buried oxide increases from 1.42×1017 cm-3·eV-1 to 6.16×1018 cm-3·eV-1. Based on carrier mobility fluctuation theory, the extracted average Hooge’s parameter in these devices increases from 3.92×10-5 to 1.34×10-2 after ion implantation processing. Finally, radiation responses in the PDSOI devices are investigated. Owing to radiation-induced positive buried oxide trapped charges, back gate threshold voltage decreases with the increase of the total dose. After radiation reaches up to a total dose of 1 M·rad(si), the shifts of back gate threshold voltage in the SOI devices with and without ion implantation are -10.82 V and -31.84 V, respectively. The low frequency noise behaviors in these devices before and after radiation are also compared and discussed. Project supported by the National Natural Science Foundation of China (Grant Nos. 61204112 and 61204116).

  7. The effect of ambient humidity on the electrical response of ion-migration-based polymer sensor with various cations

    NASA Astrophysics Data System (ADS)

    Zhu, Zicai; Horiuchi, Tetsuya; Kruusamäe, Karl; Chang, Longfei; Asaka, Kinji

    2016-05-01

    A water-based ionic polymer-metal composite (IPMC) sensor, induced by ion migration, is a promising alternative to natural sensing systems. Focusing on water effects, this paper investigated the voltage responses of Au-Nafion IPMC at multiple fixed levels of ambient humidity under a small step bending deformation. The voltage includes two processes: a fast rising and a subsequent slow decay. As the relative ambient humidity decreases, the peak voltage first increases and then decreases because the mass storage capacity of IPMC, related to the compressed state of a polymer network, reaches the optimum at a moderate water content (30 ˜ 90%RH), whereas the proportion of decay related to hydration effect decreases as the level of relative humidity is decreased. The detailed physics has been revealed qualitatively based on transport theory, and a fitting equation has been proposed to approximate the general electrical response.

  8. Analysis of cellular responses of macrophages to zinc ions and zinc oxide nanoparticles: a combined targeted and proteomic approach

    NASA Astrophysics Data System (ADS)

    Triboulet, Sarah; Aude-Garcia, Catherine; Armand, Lucie; Gerdil, Adèle; Diemer, Hélène; Proamer, Fabienne; Collin-Faure, Véronique; Habert, Aurélie; Strub, Jean-Marc; Hanau, Daniel; Herlin, Nathalie; Carrière, Marie; van Dorsselaer, Alain; Rabilloud, Thierry

    2014-05-01

    Two different zinc oxide nanoparticles, as well as zinc ions, are used to study the cellular responses of the RAW 264 macrophage cell line. A proteomic screen is used to provide a wide view of the molecular effects of zinc, and the most prominent results are cross-validated by targeted studies. Furthermore, the alteration of important macrophage functions (e.g. phagocytosis) by zinc is also investigated. The intracellular dissolution/uptake of zinc is also studied to further characterize zinc toxicity. Zinc oxide nanoparticles dissolve readily in the cells, leading to high intracellular zinc concentrations, mostly as protein-bound zinc. The proteomic screen reveals a rather weak response in the oxidative stress response pathway, but a strong response both in the central metabolism and in the proteasomal protein degradation pathway. Targeted experiments confirm that carbohydrate catabolism and proteasome are critical determinants of sensitivity to zinc, which also induces DNA damage. Conversely, glutathione levels and phagocytosis appear unaffected at moderately toxic zinc concentrations.Two different zinc oxide nanoparticles, as well as zinc ions, are used to study the cellular responses of the RAW 264 macrophage cell line. A proteomic screen is used to provide a wide view of the molecular effects of zinc, and the most prominent results are cross-validated by targeted studies. Furthermore, the alteration of important macrophage functions (e.g. phagocytosis) by zinc is also investigated. The intracellular dissolution/uptake of zinc is also studied to further characterize zinc toxicity. Zinc oxide nanoparticles dissolve readily in the cells, leading to high intracellular zinc concentrations, mostly as protein-bound zinc. The proteomic screen reveals a rather weak response in the oxidative stress response pathway, but a strong response both in the central metabolism and in the proteasomal protein degradation pathway. Targeted experiments confirm that carbohydrate

  9. Ion Outflow Response to the ICME on 29 October-03 November 2004 and the ICME on 07-13 November 2004

    NASA Astrophysics Data System (ADS)

    Elliott, H. A.; Jahn, J.

    2005-05-01

    We examine the flux of ions outflowing from the polar ionosphere into the magnetosphere in response to two different Interplanetary Coronal Mass Ejections (ICMEs). We discuss differences in the solar wind conditions and then compare and contrast different outflow responses. We examine the outflowing thermal ions that flow away from the Earth along magnetic field lines. Previous simulation studies indicate that such outflowing ions can travel to the plasma sheet and ring current. Most of the field-aligned outward moving ions we observe during these storms appears to be O+. The flux of O+ outflowing ions has been shown to increase linearly with increasing solar wind pressure. However, much of the previous work was done over a limited range of solar wind dynamic pressures. We look at these ICMEs, which have large solar wind pressures, to determine if the outflow response is linear at higher pressures. We use ion measurements from the Thermal Ion Dynamics Experiment (TIDE) on the Polar spacecraft and solar wind measurements from the Solar Wind Electron Proton Alpha Monitor (SWEPAM) on the ACE spacecraft.

  10. Effects of coating rectangular microscopic electrophoresis chamber with methylcellulose

    NASA Technical Reports Server (NTRS)

    Plank, L. D.

    1985-01-01

    One of the biggest problems in obtaining high accuracy in microscopic electrophoresis is the parabolic flow of liquid in the chamber due to electroosmotic backflow during application of the electric field. In chambers with glass walls the source of polarization leading to electroosmosis is the negative charge of the silicare and other ions that form the wall structure. It was found by Hjerten, who used a rotating 3.0 mm capillary tube for free zone electrophoresis, that precisely neutralizing this charge was extremely difficult, but if a neutral polymer matrix (formaldehyde fixed methylcellulose) was formed over the glass (quartz) wall the double layer was displaced and the viscosity at the shear plane increased so that electroosmotic flow could be eliminated. Experiments were designed to determine the reliability with which methylcellulose coating of the Zeiss Cytopherometer chamber reduced electroosmotic backflow and the effect of coating on the accuracy of cell electrophoretic mobility (EPN) determinations. Fixed rat erythrocytes (RBC) were used as test particles.

  11. The PEP-II Lower Pressure HER Vacuum Chamber

    SciTech Connect

    DeBarger, S.; Metcalfe, S.; Seeman, J.; Sullivan, M.; Wienands, U.; Wright, D.; /SLAC

    2006-03-13

    This new vacuum chamber has been installed from 12 to 21 meters upstream of the BaBar detector in the PEP-II High Energy Ring (HER) to reduce lost particle backgrounds. The backgrounds from HER now dominate the backgrounds in the BaBar detector and the present vacuum pressure is 1 x 10{sup -9} Torr. The new chamber will increase the pumping significantly by adding 18 x 2000 l/s titanium sublimation pumps to the existing 5 x 440 l/s ion pumps, and is expected to reduce the pressure by about a factor of five. Features of the chamber include improved water cooling, improved vacuum conductance through copper RF screens featuring over 15,000 small square holes and the ability to sublimate titanium while the beam is still on.

  12. Chamber Design for the Laser Inertial Fusion Energy (LIFE) Engine

    SciTech Connect

    Latkowski, J F; Abbott, R P; Aceves, S; Anklam, T; Badders, D; Cook, A W; DeMuth, J; Divol, L; El-Dasher, B; Farmer, J C; Flowers, D; Fratoni, M; ONeil, R G; Heltemes, T; Kane, J; Kramer, K J; Kramer, R; Lafuente, A; Loosmore, G A; Morris, K R; Moses, G A; Olson, B; Pantano, C; Reyes, S; Rhodes, M; Roe, K; Sawicki, R; Scott, H; Spaeth, M; Tabak, M; Wilks, S

    2010-11-30

    The Laser Inertial Fusion Energy (LIFE) concept is being designed to operate as either a pure fusion or hybrid fusion-fission system. The present work focuses on the pure fusion option. A key component of a LIFE engine is the fusion chamber subsystem. It must absorb the fusion energy, produce fusion fuel to replace that burned in previous targets, and enable both target and laser beam transport to the ignition point. The chamber system also must mitigate target emissions, including ions, x-rays and neutrons and reset itself to enable operation at 10-15 Hz. Finally, the chamber must offer a high level of availability, which implies both a reasonable lifetime and the ability to rapidly replace damaged components. An integrated design that meets all of these requirements is described herein.

  13. Response of nanostructured ferritic alloys to high-dose heavy ion irradiation

    SciTech Connect

    Parish, Chad M.; White, Ryan M.; LeBeau, James M.; Miller, Michael K.

    2014-02-01

    A latest-generation aberration-corrected scanning/transmission electron microscope (STEM) is used to study heavy-ion-irradiated nanostructured ferritic alloys (NFAs). Results are presented for STEM X-ray mapping of NFA 14YWT irradiated with 10 MeV Pt to 16 or 160 dpa at -100°C and 750°C, as well as pre-irradiation reference material. Irradiation at -100°C results in ballistic destruction of the beneficial microstructural features present in the pre-irradiated reference material, such as Ti-Y-O nanoclusters (NCs) and grain boundary (GB) segregation. Irradiation at 750°C retains these beneficial features, but indicates some coarsening of the NCs, diffusion of Al to the NCs, and a reduction of the Cr-W GB segregation (or solute excess) content. Ion irradiation combined with the latest-generation STEM hardware allows for rapid screening of fusion candidate materials and improved understanding of irradiation-induced microstructural changes in NFAs.

  14. In situ study of heavy ion irradiation response of immiscible Cu/Fe multilayers

    DOE PAGES

    Chen, Youxing; Li, Nan; Bufford, Daniel Charles; ...

    2016-04-09

    By providing active defect sinks that capture and annihilate radiation induced defect clusters immiscible metallic multilayers with incoherent interfaces can effectively reduce defect density in ion irradiated metals. Although it is anticipated that defect density within the layers should vary as a function of distance to the layer interface, there is, to date, little in situ TEM evidence to validate this hypothesis. In our study monolithic Cu films and Cu/Fe multilayers with individual layer thickness, h, of 100 and 5 nm were subjected to in situ Cu ion irradiation at room temperature to nominally 1 displacement-per-atom inside a transmission electronmore » microscope. Rapid formation and propagation of defect clusters were observed in monolithic Cu, whereas fewer defects with smaller dimensions were generated in Cu/Fe multilayers with smaller h. Moreover, in situ video shows that the cumulative defect density in Cu/Fe 100 nm multilayers indeed varies, as a function of distance to the layer interfaces, supporting a long postulated hypothesis.« less

  15. In situ study of heavy ion irradiation response of immiscible Cu/Fe multilayers

    SciTech Connect

    Chen, Youxing; Li, Nan; Bufford, Daniel Charles; Li, Jin; Hattar, Khalid Mikhiel; Wang, Haiyan; Zhang, Xinghang

    2016-04-09

    By providing active defect sinks that capture and annihilate radiation induced defect clusters immiscible metallic multilayers with incoherent interfaces can effectively reduce defect density in ion irradiated metals. Although it is anticipated that defect density within the layers should vary as a function of distance to the layer interface, there is, to date, little in situ TEM evidence to validate this hypothesis. In our study monolithic Cu films and Cu/Fe multilayers with individual layer thickness, h, of 100 and 5 nm were subjected to in situ Cu ion irradiation at room temperature to nominally 1 displacement-per-atom inside a transmission electron microscope. Rapid formation and propagation of defect clusters were observed in monolithic Cu, whereas fewer defects with smaller dimensions were generated in Cu/Fe multilayers with smaller h. Moreover, in situ video shows that the cumulative defect density in Cu/Fe 100 nm multilayers indeed varies, as a function of distance to the layer interfaces, supporting a long postulated hypothesis.

  16. ION SOURCE (R.F. INDUCTION TYPE)

    DOEpatents

    Mills, C.B.

    1963-04-01

    A method is given for producing energetic ions by ionizing a gas with an oscillating electric field which is parallel to a confining magnetic field, then reorienting the fields perpendicular to each other to accelerate the ions to higher energies. An ion source is described wherein a secondary coil threads the bottom of a rectangular ionization chamber and induces an oscillating field parallel to a fixed intense magnetic field through the chamber. (AEC)

  17. Surface Response of Lithium Coatings on High Z Refractory Metal under Deuterium And Helium Ion Bombardment

    NASA Astrophysics Data System (ADS)

    Neff, Anton L.

    Lithium has proven to be a very interesting plasma facing component (PFC) material. It has been used as a wall coating in multiple research tokamaks, and at many of these facilities, lithium has improved confinement time by reducing hydrogen recycling from the walls of the reactor. Tungsten is also being considered as a durable PFC for fusion environments. The International Tokamak Experimental Reactor (ITER) will use a full tungsten divertor. Many operating tokamaks are using ITER like walls for testing ITER designs. From these tests and from controlled experiments, tungsten has shown some detrimental material changes under low energy deuterium and helium ion irradiation. Some of these material defects are holes, bubbles, voids, and fuzz. Because of the use of lithium in a number of tokamaks and the use of tungsten in many test reactors as well, studies have begun to study the behavior of lithium on the refractory metal tungsten. These studies deposited 100 and 500 nm of lithium on commercial tungsten discs and irradiated them with 100 eV deuterium, 1 keV helium, and deuterium and helium from two separate ion guns. The thicknesses of the lithium layers were determined by the temperature of the evaporator, over time, entered into a model using the Knudsen equation combined with an effusion model. This model was verified using AFM scans and SEM cross section micrographs of lithium layers on silicon substrates. Irradiations were carried out to a medium deuterium fluence of (1-3)x1017 D+/cm2. The surface chemistry of the samples before, after, and during irradiation was characterized using x-ray electron spectroscopy (XPS) in situ. These studies show that lithium on tungsten retains deuterium in a similar manner as does lithium on carbon; however, when helium is a secondary ion during irradiation, it can inhibit the deuterium retention in the lithium. In addition, the lithium is not eroded from the surface of the tungsten at the fluences that were achieved is this

  18. Expression of NF-kappaB dependent genes in human cells in response to heavy ion beams

    NASA Astrophysics Data System (ADS)

    Hellweg, Christine; Baumstark-Khan, Christa; Ruland, Rebecca; Schmitz, Claudia; Lau, Patrick; Testard, Isabelle; Reitz, Guenther

    Space radiation is a primary concern for manned spaceflight and is a potentially limiting factor for long term orbital and interplanetary missions. Understanding of the cellular and molecular processes underlying cell death and transformation related events by space radiation may allow better risk estimation and development of appropriate countermeasures. The pathway leading to activation of the transcription factor nuclear factor κB (NF-κB) and increased transcription of its target gene might modulate cellular radiation response. Previous studies suggest a linear energy transfer (LET) dependency of transcription factor nuclear factor κB (NF-κB) activation: high LET radiation activates NF-κB more efficiently than low LET radiation. In this work, the relative expressions of several NF-κB regulated genes (Gadd45β, NFKBIA encoding the NF-κB inhibitor IκBα, and the anti-apoptotic genes XIAP, bcl-2, and bcl-xL) were examined by quantitative real-time Reverse Transcriptase Polymerase Chain Reaction (qRT-PCR). Human embryonic cells with neuronal differentiation potential (HEK/293) were exposed to accelerated heavy ions or to X-rays (200 kV) or incubated in presence of the strong NF-κB activator tumor necrosis factor α (TNF-α). Target gene expression data were normalized to the expression index of several unregulated reference genes (B2M, GAPDH, PBGD, HPRT). NFKBIA expression is enhanced for 24 h after TNF-α treatment, while Gadd45β expression was only temporarily up-regulated. High doses of X-rays (8 and 16 Gy) and of 13 C ions (75 MeV/n, LET 33 keV/µm, 4.7 Gy) up-regulate NFKBIA and Gadd45β expression temporarily. 13 C ion with higher LET (35 MeV/n, 73 keV/µm) enhance NFKBIA expression already after 1 Gy, and a passing up-regulation of Bcl-2, bcl-xL and XIAP expression was observed 2 h after 0.5 Gy. 20 Ne (95 MeV/A, 80 keV/µm) and 36 Ar ions (95 MeV/A, 271 keV/µm) were the strongest inducers of Gadd45β, NFKBIA, and XIAP with doses from 0.5 to 3.8 Gy

  19. Pulsed discharge ionization source for miniature ion mobility spectrometers

    DOEpatents

    Xu, Jun; Ramsey, J. Michael; Whitten, William B.

    2004-11-23

    A method and apparatus is disclosed for flowing a sample gas and a reactant gas (38, 43) past a corona discharge electrode (26) situated at a first location in an ion drift chamber (24), applying a pulsed voltage waveform comprising a varying pulse component and a dc bias component to the corona discharge electrode (26) to cause a corona which in turn produces ions from the sample gas and the reactant gas, applying a dc bias to the ion drift chamber (24) to cause the ions to drift to a second location (25) in the ion drift chamber (24), detecting the ions at the second location (25) in the drift chamber (24), and timing the period for the ions to drift from the corona discharge electrode to the selected location in the drift chamber.

  20. 63. Interior view, kitchen chamber, north elevation. The kitchen chamber ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    63. Interior view, kitchen chamber, north elevation. The kitchen chamber was completed in the first stages of phase III construction. The paneled wall to the fireplace's right displays a phase III molding profile. The mark between the cabinet doors and on the large lower panel indicates the former position of a partition wall. The chimney-breast paneling bears a phase I profile and might have been moved to the room when the fireplace mass in the hall was reduced. - John Bartram House & Garden, House, 54th Street & Lindbergh Boulevard, Philadelphia, Philadelphia County, PA

  1. Plasma chemistry in wire chambers

    SciTech Connect

    Wise, J.

    1990-05-01

    The phenomenology of wire chamber aging is discussed and fundamentals of proportional counters are presented. Free-radical polymerization and plasma polymerization are discussed. The chemistry of wire aging is reviewed. Similarities between wire chamber plasma (>1 atm dc-discharge) and low-pressure rf-discharge plasmas, which have been more widely studied, are suggested. Construction and use of a system to allow study of the plasma reactions occurring in wire chambers is reported. A proportional tube irradiated by an {sup 55}Fe source is used as a model wire chamber. Condensable species in the proportional tube effluent are concentrated in a cryotrap and analyzed by gas chromatography/mass spectrometry. Several different wire chamber gases (methane, argon/methane, ethane, argon/ethane, propane, argon/isobutane) are tested and their reaction products qualitatively identified. For all gases tested except those containing methane, use of hygroscopic filters to remove trace water and oxygen contaminants from the gas resulted in an increase in the average molecular weight of the products, consistent with results from low-pressure rf-discharge plasmas. It is suggested that because water and oxygen inhibit polymer growth in the gas phase that they may also reduce polymer deposition in proportional tubes and therefore retard wire aging processes. Mechanistic implications of the plasma reactions of hydrocarbons with oxygen are suggested. Unresolved issues in this work and proposals for further study are discussed.

  2. Emulsion Chamber Technology Experiment (ECT)

    NASA Technical Reports Server (NTRS)

    Gregory, John C.; Takahashi, Yoshiyuki

    1996-01-01

    The experimental objective of Emulsion Chamber Technology (ECT) was to develop space-borne emulsion chamber technology so that cosmic rays and nuclear interactions may subsequently be studied at extremely high energies with long exposures in space. A small emulsion chamber was built and flown on flight STS-62 of the Columbia in March 1994. Analysis of the several hundred layers of radiation-sensitive material has shown excellent post-flight condition and suitability for cosmic ray physics analysis at much longer exposures. Temperature control of the stack was 20 +/-1 C throughout the active control period and no significant deviations of temperature or pressure in the chamber were observed over the entire mission operations period. The unfortunate flight attitude of the orbiter (almost 90% Earth viewing) prevented any significant number of heavy particles (Z greater than or equal to 10) reaching the stack and the inverted flow of shower particles in the calorimeter has not allowed evaluation of absolute primary cosmic ray-detection efficiency nor of the practical time limits of useful exposure of these calorimeters in space to the level of detail originally planned. Nevertheless, analysis of the observed backgrounds and quality of the processed photographic and plastic materials after the flight show that productive exposures of emulsion chambers are feasible in low orbit for periods of up to one year or longer. The engineering approaches taken in the ECT program were proven effective and no major environmental obstacles to prolonged flight are evident.

  3. Plant growth chamber M design

    NASA Technical Reports Server (NTRS)

    Prince, R. P.; Knott, W. M.

    1986-01-01

    Crop production is just one of the many processes involved in establishing long term survival of man in space. The benefits of integrating higher plants into the overall plan was recognized early by NASA through the Closed Ecological Life Support System (CELSS) program. The first step is to design, construct, and operate a sealed (gas, liquid, and solid) plant growth chamber. A 3.6 m diameter by 6.7 m high closed cylinder (previously used as a hypobaric vessel during the Mercury program) is being modified for this purpose. The chamber is mounted on legs with the central axis vertical. Entrance to the chamber is through an airlock. This chamber will be devoted entirely to higher plant experimentation. Any waste treatment, food processing or product storage studies will be carried on outside of this chamber. Its primary purpose is to provide input and output data on solids, liquids, and gases for single crop species and multiple species production using different nutrient delivery systems.

  4. Iridium-Coated Rhenium Combustion Chamber

    NASA Technical Reports Server (NTRS)

    Schneider, Steven J.; Tuffias, Robert H.; Rosenberg, Sanders D.

    1994-01-01

    Iridium-coated rhenium combustion chamber withstands operating temperatures up to 2,200 degrees C. Chamber designed to replace older silicide-coated combustion chamber in small rocket engine. Modified versions of newer chamber could be designed for use on Earth in gas turbines, ramjets, and scramjets.

  5. Nonlinear luminescence response of CaF{sub 2}:Eu and YAlO{sub 3}:Ce to single-ion excitation

    SciTech Connect

    Liu, Peng; Zhang, Yanwen Weber, William J.; Xiao, Haiyan; Xiang, Xia; Wang, Xuelin

    2014-01-21

    Understanding scintillation physics and nonproportionality is essential to accelerate materials discovery that has been restricted due to the difficulties inherent to large crystal growth and complex nature of gamma-solid interaction. Taking advantage of less restrictive growth and deposition techniques for smaller crystal sizes or thin films and better fundamental understanding of ion-solid interactions, a unique ion approach is demonstrated to effectively screen candidate scintillators with relatively small size and evaluate their nonlinear scintillation response. Response of CaF{sub 2}:Eu and YAlO{sub 3}:Ce scintillators to single ions of H{sup +}, He{sup +}, and O{sup 3+} are measured by the corresponding pulse height over a continuous energy range using a time-of-flight–scintillator–photoelectric multiplier tube apparatus. Nonlinear response of the scintillators under ionizing ion irradiation is quantitatively evaluated by considering the energy partitioning process. In a differential energy deposition region with negligible displacement damage, the low, medium and high excitation energy deposition density (D{sub exci}) can be produced by energetic H{sup +}, He{sup +} and O{sup 3+} ions, respectively, and significantly different impacts on the response characteristics of these two benchmark scintillators are observed. For CaF{sub 2}:Eu, the scintillation efficiency under ion irradiation monotonically decreases with increasing excitation-energy density. In contrast, the response efficiency of YAlO{sub 3}:Ce scintillation initially increases with excitation-energy density at low excitation-energy densities, goes through a maximum, and then decreases with further increasing excitation-energy density. The fundamental mechanism causing these different response behaviours in the scintillators is based on the competition between the scintillation response and the nonradiative quenching process under different excitation densities, which is also the main origin of

  6. Nonlinear Luminescence Response of CaF2:Eu and YAlO3:Ce to Single-Ion Excitation

    SciTech Connect

    Liu, Peng; Zhang, Yanwen; Xiao, Haiyan Y.; Xiang, Xia; Wang, Xuelin; Weber, William J.

    2014-01-17

    Understanding scintillation physics and nonproportionality is essential to accelerate materials discovery that has been restricted due to the difficulties inherent to large crystal growth and complex nature of gamma-solid interaction. Taking advantage of less restrictive growth and deposition techniques for smaller crystal sizes or thin films and better fundamental understanding of ion-solid interactions, a unique ion approach is demonstrated to effectively screen candidate scintillators with relatively small size and evaluate their nonlinear scintillation response. Response of CaF2:Eu and YAlO3:Ce scintillators to single ions of Hþ, Heþ, and O3þ are measured by the corresponding pulse height over a continuous energy range using a time-of-flight–scintillator–photoelectric multiplier tube apparatus. Nonlinear response of the scintillators under ionizing ion irradiation is quantitatively evaluated by considering the energy partitioning process. In a differential energy deposition region with negligible displacement damage, the low, medium and high excitation energy deposition density (Dexci) can be produced by energetic Hþ, Heþ and O3þ ions, respectively, and significantly different impacts on the response characteristics of these two benchmark scintillators are observed. For CaF2:Eu, the scintillation efficiency under ion irradiation monotonically decreases with increasing excitation-energy density. In contrast, the response efficiency of YAlO3:Ce scintillation initially increases with excitation-energy density at low excitation-energy densities, goes through a maximum, and then decreases with further increasing excitation-energy density. The fundamental mechanism causing these different response behaviours in the scintillators is based on the competition between the scintillation response and the nonradiative quenching process under different excitation densities, which is also the main

  7. Novel indole based dual responsive 'turn-on' chemosensor for fluoride ion detection

    NASA Astrophysics Data System (ADS)

    Jeyanthi, Dharmaraj; Iniya, Murugan; Krishnaveni, Karuppiah; Chellappa, Duraisamy

    2015-02-01

    An efficient new dual channel chemosensor 2,3-bis((E)-(1H-indole-3-yl)methyleneamino)maleonitrile (DN) which exhibits selective sensing of F- ions in DMSO, was synthesized by a facile one step condensation reaction of indole-3-carboxaldehyde with diaminomaleonitrile. The probe DN was characterized by elemental analysis, 1H, 13C-NMR, ESI-MS and IR spectral techniques. Upon addition of F-, DN induces remarkable changes in both absorption and fluorescence spectra on the basis of charge transfer mechanism. The receptor DN serves for highly selective, sensitive detection of F- without the interference of other relevant anions. The Job's plot analysis indicates the binding stoichiometry to be 1:1 (host/guest).

  8. Response of polyatomic molecules to ultrastrong laser- and ion-induced fields.

    PubMed

    Schlathölter, T; Hoekstra, R; Zamith, S; Ni, Y; Muller, H G; Vrakking, M J J

    2005-06-17

    The exposure of molecules to short, ultrastrong electric fields leads to multiple ionization and a subsequent Coulomb explosion. We present a comparative study where uracil molecules are exposed to fields generated by high-power laser pulses (tau approximately 75 fs, I > 10(16) W/cm2) or swift highly charged ions (0.5 MeV Xe25+) representing a half-cycle pulse of less than 10 fs duration. Molecular dynamics and structural information contained in the fragmentation pathways can be assessed separately. Despite the similar field strengths large differences in fragment kinetic energies are found which are related to field shape and duration with the aid of molecular dynamics simulations.

  9. High current ion source

    DOEpatents

    Brown, Ian G.; MacGill, Robert A.; Galvin, James E.

    1990-01-01

    An ion source utilizing a cathode and anode for producing an electric arc therebetween. The arc is sufficient to vaporize a portion of the cathode to form a plasma. The plasma leaves the generation region and expands through another regon. The density profile of the plasma may be flattened using a magnetic field formed within a vacuum chamber. Ions are extracted from the plasma to produce a high current broad on beam.

  10. Characterization and testing of a new environmental chamber

    NASA Astrophysics Data System (ADS)

    Leskinen, A.; Yli-Pirilä, P.; Kuuspalo, K.; Sippula, O.; Jalava, P.; Hirvonen, M.-R.; Jokiniemi, J.; Virtanen, A.; Komppula, M.; Lehtinen, K. E. J.

    2015-06-01

    A 29 m3 Teflon chamber, designed for studies on the aging of combustion aerosols, at the University of Eastern Finland is described and characterized. The chamber is part of a research facility, called Ilmari, where small-scale combustion devices, a dynamometer for vehicle exhaust studies, dilution systems, the chamber, and cell and animal exposure devices are located side by side under the same roof. The small surface-to-volume ratio of the chamber enables reasonably long experiment times, with particle wall loss rate constants of 0.088, 0.080, 0.045, and 0.040 h-1 for polydisperse, 50, 100, and 200 nm monodisperse aerosols, respectively. The NO2 photolysis rate can be adjusted from 0 to 0.62 min-1. The irradiance spectrum is centered at either 350 or 365 nm, and the maximum irradiance, produced by up to 160 blacklight lamps, is 29.7 W m-2, which corresponds to the ultraviolet (UV) irradiance in Central Finland at noon on a sunny day in the midsummer. The temperature inside the chamber is uniform and can be kept at 25±1 °C. The chamber is kept in an overpressure with a moving top frame, which reduces sample dilution and entrance of contamination during an experiment. The functionality of the chamber was tested with oxidation experiments of toluene, resulting in secondary organic aerosol (SOA) yields of 12-42%, depending on the initial conditions, such as NOx concentration and UV irradiation. The highest gaseous oxidation product yields of 12.4-19.5% and 5.8-19.5% were detected with ions corresponding to methyl glyoxal (m/z 73.029) and 4-oxo-2-pentenal (m/z 99.044), respectively. Overall, reasonable yields of SOA and gaseous reaction products, comparable to those obtained in other laboratories, were obtained.

  11. Hydrostatic Hyperbaric Chamber Ventilation System

    NASA Technical Reports Server (NTRS)

    Sargusingh, Miriam M.

    2011-01-01

    The hydrostatic hyperbaric chamber (HHC) represents the merger of several technologies in development for NASA aerospace applications, harnessed to directly benefit global health. NASA has significant experience developing composite hyperbaric chambers for a variety of applications, including the treatment of medical conditions. NASA also has researched the application of water-filled vessels to increase tolerance of acceleration forces. The combination of these two applications has resulted in the hydrostatic chamber, which has been conceived as a safe, affordable means of making hyperbaric oxygen therapy available in the developing world for the treatment of a variety of medical conditions. Specifically, hyperbaric oxygen therapy is highly-desired as a possibly curative treatment for Buruli Ulcer, an infectious condition that afflicts children in sub-Saharan Africa. Hyperbaric oxygen therapy is simply too expensive and too dangerous to implement in the developing world using standard equipment. The hydrostatic hyperbaric chamber technology changes the paradigm. The HHC differs from standard hyperbaric chambers in that the majority of its volume is filled with water which is pressurized by oxygen being supplied in the portion of the chamber containing the patient s head. This greatly reduces the amount of oxygen required to sustain a hyperbaric atmosphere, thereby making the system more safe and economical to operate. An effort was taken to develop an HHC system to apply HBOT to children that is simple and robust enough to support transport, assembly, maintenance and operation in developing countries. This paper details the concept for an HHC ventilation and pressurization system that will provide controlled pressurization of the system, and provide adequate washout of carbon dioxide while the subject is enclosed in the confined space during the administration of the medical treatment. The concept took into consideration operational complexity, safety to the

  12. Annular-Cross-Section CFE Chamber

    NASA Technical Reports Server (NTRS)

    Sharnez, Rizwan; Sammons, David W.

    1994-01-01

    Proposed continuous-flow-electrophoresis (CFE) chamber of annular cross section offers advantages over conventional CFE chamber, and wedge-cross-section chamber described in "Increasing Sensitivity in Continuous-Flow Electrophoresis" (MFS-26176). In comparison with wedge-shaped chamber, chamber of annular cross section virtually eliminates such wall effects as electro-osmosis and transverse gradients of velocity. Sensitivity enhanced by incorporating gradient maker and radial (collateral) flow.

  13. CHAMBERS FERRY ROADLESS AREA, TEXAS.

    USGS Publications Warehouse

    Houser, B.B.; Ryan, George S.

    1984-01-01

    A geologic and geochemical investigation of the Chambers Ferry Roadless Area, Texas was conducted. The area has probable mineral-resource potential for oil and gas and for lignite. No metallic or additional energy resources were identified in the investigation. Detailed analyses of well logs from the vicinity of the Chambers Ferry Roadless Area, in conjunction with seismic data, are necessary to determine if the subsurface stratigraphy and structure are favorable for the accumulation of oil and gas. A shallow drilling program involving coring on a close-space grid is necessary for determination of the rank and continuity of seams of lignitic sediments in the area.

  14. Test chamber for alpha spectrometry

    DOEpatents

    Larsen, Robert P.

    1977-01-01

    Alpha emitters for low-level radiochemical analysis by measurement of alpha spectra are positioned precisely with respect to the location of a surface-barrier detector by means of a chamber having a removable threaded planchet holder. A pedestal on the planchet holder holds a specimen in fixed engagement close to the detector. Insertion of the planchet holder establishes an O-ring seal that permits the chamber to be pumped to a desired vacuum. The detector is protected against accidental contact and resulting damage.

  15. SU-E-T-228: Liquid Ionisation Chamber Array and MicroDiamond Measurements with the CyberKnife System

    SciTech Connect

    Poppinga, D; Looe, H; Stelljes, T; Poppe, B; Blanck, O; Harder, D

    2014-06-01

    Purpose: The aim of this study was to measure the dose profile and output factors with a CyberKnife accelerator using a TM60019 microDiamond detector and a 1000SRS liquid chamber array (both PTW Freiburg, Germany). Methods: An MP3 water phantom (PTW, Freiburg) was positioned along the robotic world coordinate system. The TM60019 detector was adjusted to the center of the according fields and the semiconductor axis was aligned with the beam direction. Profiles at 5cm water depth and SSD = 80 cm were measured along the robotic x axis and y axis for the cylindrical collimators of the CyberKnife (diameter 60, 50, 40, 30, 20, 15, 12.5, 10, 7.5 and 5mm). To determine the output factors the dose profile was measured at 0.1 mm steps around the field center to find the maximum dose value. The liquid chamber array (1000SRS) measurement was performed with the same setup, but with RW3 buildup. Results: The 1000SRS measurements closely conform with the TM60019 profile measurement in all profile regions and for all collimator sizes. The profile measurement is influenced by the almost equal spatial resolution of the TM60019 detector (radius of the sensitive area 1.1mm) and of the 1000SRS liquid chamber array (single chamber width 2.3mm). The measured dose profiles have not been corrected for this limited spatial resolution. Rather we purpose to consider that spatial dose averaging over 2 mm wide regions might be justified in view of patient positioning inaccuracies and of the spaces in tissue participating in the biological radiation responses. Conclusion: The 1000SRS data points conform with the TM60019 profile measurements at all profile regions showing the applicability of liquid ion chamber arrays with the CyberKnife system.

  16. Using sputter coated glass to stabilize microstrip gas chambers

    DOEpatents

    Gong, Wen G.

    1997-01-01

    By sputter coating a thin-layer of low-resistive, electronically-conductive glass on various substrates (including quartz and ceramics, thin-film Pestov glass), microstrip gas chambers (MSGC) of high gain stability, low leakage current, and a high rate capability can be fabricated. This design can make the choice of substrate less important, save the cost of ion-implantation, and use less glass material.

  17. Rational design of heat-set and specific-ion-responsive supramolecular hydrogels based on the Hofmeister effect.

    PubMed

    Nebot, Vicent J; Ojeda-Flores, Juan J; Smets, Johan; Fernández-Prieto, Susana; Escuder, Beatriu; Miravet, Juan F

    2014-10-27

    Smart supramolecular hydrogels have been prepared from a bolaamphiphilic L-valine derivative in aqueous solutions of different salts. The hydrogels respond selectively to different ions and are either reinforced or weakened. In one case, in contrast to conventional systems, the hydrogels are formed upon heating of the system. The use of the hydrogels in the controlled release of an entrapped dye is described as a proof of the potential applications of these systems. The responsive hydrogels were rationally designed by taking into account the noticeable effect of different ions from the Hofmeister series in the solubility of the hydrogelator, which was assessed by using NMR experiments. On the one hand, kosmotropic anions such as sulfate produce a remarkable solubility decrease in the gelator, which is associated with gel reinforcement, as measured by rheological experiments. On the other hand, chaotropic species such as perchlorate weaken the gel. A dramatic effect was observed in the presence of guanidinium chloride, which boosted the solubility of the gelator, in accordance with its chaotropic behaviour reported in protein science. In this case, a direct interaction of the guanidinium species with the carbonyl groups of the hydrogelator is detected by (13) C NMR spectroscopy. The weakening of this interaction upon a temperature increase allows for the preparation of heat-set hydrogelating systems.

  18. Intracellular Calcium Mobilization in Response to Ion Channel Regulators via a Calcium-Induced Calcium Release Mechanism

    PubMed Central

    Petrou, Terry; Olsen, Hervør L.; Thrasivoulou, Christopher; Masters, John R.; Ashmore, Jonathan F.

    2017-01-01

    Free intracellular calcium ([Ca2+]i), in addition to being an important second messenger, is a key regulator of many cellular processes including cell membrane potential, proliferation, and apoptosis. In many cases, the mobilization of [Ca2+]i is controlled by intracellular store activation and calcium influx. We have investigated the effect of several ion channel modulators, which have been used to treat a range of human diseases, on [Ca2+]i release, by ratiometric calcium imaging. We show that six such modulators [amiodarone (Ami), dofetilide, furosemide (Fur), minoxidil (Min), loxapine (Lox), and Nicorandil] initiate release of [Ca2+]i in prostate and breast cancer cell lines, PC3 and MCF7, respectively. Whole-cell currents in PC3 cells were inhibited by the compounds tested in patch-clamp experiments in a concentration-dependent manner. In all cases [Ca2+]i was increased by modulator concentrations comparable to those used clinically. The increase in [Ca2+]i in response to Ami, Fur, Lox, and Min was reduced significantly (P < 0.01) when the external calcium was reduced to nM concentration by chelation with EGTA. The data suggest that many ion channel regulators mobilize [Ca2+]i. We suggest a mechanism whereby calcium-induced calcium release is implicated; such a mechanism may be important for understanding the action of these compounds. PMID:27980039

  19. Lightweight Chambers for Thrust Assemblies

    NASA Technical Reports Server (NTRS)

    Elam, Sandra K.; Lee, Jonathan; Holmes, Richard; Zimmerman, Frank; Effinger, Mike; Turner, James E. (Technical Monitor)

    2001-01-01

    The Marshall Space Flight Center (MSFC) of the National Aeronautics and Space Administration (NASA) has successfully applied new materials and fabrication techniques to create actively cooled thrust chambers that operate 200-400 degrees hotter and weigh 50% lighter than conventional designs. In some vehicles, thrust assemblies account for as much as 20% of the engine weight. So, reducing the weight of these components and increasing their operating range will benefit many engines and vehicle designs, including Reusable Launch Vehicle (RLV) concepts. Obviously, copper and steel alloys have been used successfully for many years in the chamber components of thrust assemblies. Yet, by replacing the steel alloys with Polymer Matrix Composite (PMC) and/or Metal Matrix Composite (MMC) materials, design weights can be drastically reduced. In addition, replacing the traditional copper alloys with a Ceramic Matrix Composite (CMC) or an advanced copper alloy (Cu-8Cr-4Nb, also known as GRCop-84) significantly increases allowable operating temperatures. Several small MMC and PMC demonstration chambers have recently been fabricated with promising results. Each of these designs included GRCop-84 for the cooled chamber liner. These units successfully verified that designs over 50% lighter are feasible. New fabrication processes, including advanced casting technology and a low cost vacuum plasma spray (VPS) process, were also demonstrated with these units. Hot-fire testing at MSFC is currently being conducted on the chambers to verify increased operating temperatures available with the GRCop-84 liner. Unique CMC chamber liners were also successfully fabricated and prepared for hot-fire testing. Yet, early results indicate these CMC liners need significantly more development in order to use them in required chamber designs. Based on the successful efforts with the MMC and PMC concepts, two full size "lightweight" chambers are currently being designed and fabricated for hot

  20. Detection of Chamber Conditioning Through Optical Emission and Impedance Measurements

    NASA Technical Reports Server (NTRS)

    Cruden, Brett A.; Rao, M. V. V. S.; Sharma, Surendra P.; Meyyappan, Meyya

    2001-01-01

    During oxide etch processes, buildup of fluorocarbon residues on reactor sidewalls can cause run-to-run drift and will necessitate some time for conditioning and seasoning of the reactor. Though diagnostics can be applied to study and understand these phenomena, many of them are not practical for use in an industrial reactor. For instance, measurements of ion fluxes and energy by mass spectrometry show that the buildup of insulating fluorocarbon films on the reactor surface will cause a shift in both ion energy and current in an argon plasma. However, such a device cannot be easily integrated into a processing system. The shift in ion energy and flux will be accompanied by an increase in the capacitance of the plasma sheath. The shift in sheath capacitance can be easily measured by a common commercially available impedance probe placed on the inductive coil. A buildup of film on the chamber wall is expected to affect the production of fluorocarbon radicals, and thus the presence of such species in the optical emission spectrum of the plasma can be monitored as well. These two techniques are employed on a GEC (Gaseous Electronics Conference) Reference Cell to assess the validity of optical emission and impedance monitoring as a metric of chamber conditioning. These techniques are applied to experimental runs with CHF3 and CHF3/O2/Ar plasmas, with intermediate monitoring of pure argon plasmas as a reference case for chamber conditions.

  1. Statistics of initial density perturbations in heavy ion collisions and their fluid dynamic response

    NASA Astrophysics Data System (ADS)

    Floerchinger, Stefan; Wiedemann, Urs Achim

    2014-08-01

    An interesting opportunity to determine thermodynamic and transport properties in more detail is to identify generic statistical properties of initial density perturbations. Here we study event-by-event fluctuations in terms of correlation functions for two models that can be solved analytically. The first assumes Gaussian fluctuations around a distribution that is fixed by the collision geometry but leads to non-Gaussian features after averaging over the reaction plane orientation at non-zero impact parameter. In this context, we derive a three-parameter extension of the commonly used Bessel-Gaussian event-by-event distribution of harmonic flow coefficients. Secondly, we study a model of N independent point sources for which connected n-point correlation functions of initial perturbations scale like 1 /N n-1. This scaling is violated for non-central collisions in a way that can be characterized by its impact parameter dependence. We discuss to what extent these are generic properties that can be expected to hold for any model of initial conditions, and how this can improve the fluid dynamical analysis of heavy ion collisions.

  2. Method to calibrate fission chambers in Campbelling mode

    SciTech Connect

    Benoit Geslot; Troy C. Unruh; Philippe Filliatre; Christian Jammes; Jacques Di Salvo; Stéphane Bréaud; Jean-François Villard

    2011-06-01

    Fission chambers are neutron detectors which are widely used to instrument experimental reactors such as material testing reactors or zero power reactors. In the presence of a high level mixed gamma and neutron flux, fission chambers can be operated in Campbelling mode (also known as 'fluctuation mode' or 'mean square voltage mode') to provide reliable and precise neutron related measurements. Fission chamber calibration in Campbelling mode (in terms of neutron flux) is usually done empirically using a calibrated reference detector. A major drawback of this method is that calibration measurements have to be performed in a neutron environment very similar to the one in which the calibrated detector will be used afterwards. What we propose here is a different approach based on characterizing the fission chamber response in terms of fission rate. This way, the detector calibration coefficient is independent from the neutron spectrum and can be determined prior to the experiment. The fissile deposit response to the neutron spectrum can then be assessed independently by other means (experimental or numerical). In this paper, the response of CEA made miniature fission chambers in Campbelling mode is studied. We use a theoretical model of the signal to calculate the calibration coefficient. Input parameters of the model come from statistical distribution of individual pulses. Supporting measurements have been made in the CEA Cadarache zero power reactor MINERVE. Results are compared to an empirical Campbelling mode calibration.

  3. Mini RF-driven ion source for focused ion beam system

    SciTech Connect

    Jiang, X.; Ji, Q.; Chang, A.; Leung, K.N.

    2002-08-02

    Mini RF-driven ion sources with 1.2 cm and 1.5 cm inner chamber diameter have been developed at Lawrence Berkeley National Laboratory. Several gas species have been tested including argon, krypton and hydrogen. These mini ion sources operate in inductively coupled mode and are capable of generating high current density ion beams at tens of watts. Since the plasma potential is relatively low in the plasma chamber, these mini ion sources can function reliably without any perceptible sputtering damage. The mini RF-driven ion sources will be combined with electrostatic focusing columns, and are capable of producing nano focused ion beams for micro machining and semiconductor fabrications.

  4. Simulation of Layered Magma Chambers.

    ERIC Educational Resources Information Center

    Cawthorn, Richard Grant

    1991-01-01

    The principles of magma addition and liquid layering in magma chambers can be demonstrated by dissolving colored crystals. The concepts of density stratification and apparent lack of mixing of miscible liquids is convincingly illustrated with hydrous solutions at room temperature. The behavior of interstitial liquids in "cumulus" piles…

  5. Nondestructive test of regenerative chambers

    NASA Technical Reports Server (NTRS)

    Malone, G. A.; Stauffis, R.; Wood, R.

    1972-01-01

    Flat panels simulating internally cooled regenerative thrust chamber walls were fabricated by electroforming, brazing and diffusion bonding to evaluate the feasibility of nondestructive evaluation techniques to detect bonds of various strength integrities. Ultrasonics, holography, and acoustic emission were investigated and found to yield useful and informative data regarding the presence of bond defects in these structures.

  6. Chamber and target technology development for inertial fusion energy

    SciTech Connect

    Abdou, M; Besenbruch, G; Duke, J; Forman, L; Goodin, D; Gulec, K; Hoffer, J; Khater, H; Kulcinsky, G; Latkowski, J F; Logan, B G; Margevicious, B; Meier, W R; Moir, R W; Morley, N; Nobile, A; Payne, S; Peterson, P F; Peterson, R; Petzoldt, R; Schultz, K; Steckle, W; Sviatoslavsky, L; Tillack, M; Ying, A

    1999-04-07

    Fusion chambers and high pulse-rate target systems for inertial fusion energy (IFE) must: regenerate chamber conditions suitable for target injection, laser propagation, and ignition at rates of 5 to 10 Hz; extract fusion energy at temperatures high enough for efficient conversion to electricity; breed tritium and fuel targets with minimum tritium inventory; manufacture targets at low cost; inject those targets with sufficient accuracy for high energy gain; assure adequate lifetime of the chamber and beam interface (final optics); minimize radioactive waste levels and annual volumes; and minimize radiation releases under normal operating and accident conditions. The primary goal of the US IFE program over the next four years (Phase I) is to develop the basis for a Proof-of-Performance-level driver and target chamber called the Integrated Research Experiment (IRE). The IRE will explore beam transport and focusing through prototypical chamber environment and will intercept surrogate targets at high pulse rep-rate. The IRE will not have enough driver energy to ignite targets, and it will be a non-nuclear facility. IRE options are being developed for both heavy ion and laser driven IFE. Fig. 1 shows that Phase I is prerequisite to an IRE, and the IRE plus NIF (Phase II) is prerequisite to a high-pulse rate. Engineering Test Facility and DEMO for IFE, leading to an attractive fusion power plant. This report deals with the Phase-I R&D needs for the chamber, driver/chamber interface (i.e., magnets for accelerators and optics for lasers), target fabrication, and target injection; it is meant to be part of a more comprehensive IFE development plan which will include driver technology and target design R&D. Because of limited R&D funds, especially in Phase I, it is not possible to address the critical issues for all possible chamber and target technology options for heavy ion or laser fusion. On the other hand, there is risk in addressing only one approach to each technology

  7. The response of a fast scintillator screen (YAP:Ce) to low energy ions (0-40 keV) and its use to detect fast-ion-loss in stellarator TJ-II.

    PubMed

    Martínez, M; Zurro, B; Baciero, A; Jiménez-Rey, D; Tribaldos, V; Malo, M; Crespo, M T; Muñoz, D

    2016-11-01

    A systematic study of scintillation materials was undertaken to improve the time resolution of the fast ion diagnostic currently installed at TJ-II stellarator. It was found that YAP:Ce (formula YAlO3:Ce, Yttrium Aluminum Perovskite doped with Cerium) ionoluminescence offers better sensitivity and time response compared to the standard detector material, SrGa2S4:Eu (TG-Green), currently used in TJ-II. A comparison between both materials was carried out by irradiating them with H(+) ions of up to 40 keV using a dedicated laboratory setup. It is found that for the low energy ions of interest at TJ-II, YAP:Ce offers 20 times higher sensitivity than TG-Green and much faster decay time, 27 ns versus 540 ns. It is expected that the use of YAP:Ce in combination with a faster data acquisition and an ion counting software as part of the TJ-II ion luminescent probe will provide 20 times faster data on ion loss.

  8. Hydrostatic Hyperbaric Chamber Ventilation System

    NASA Technical Reports Server (NTRS)

    Sarguisingh, Miriam J.

    2012-01-01

    The hydrostatic hyperbaric chamber (HHC) represents the merger of several technologies in development for NASA aerospace applications, harnessed to directly benefit global health. NASA has significant experience developing composite hyperbaric chambers for a variety of applications. NASA also has researched the application of water-filled vessels to increase tolerance of acceleration forces. The combination of these two applications has resulted in the hydrostatic chamber, which has been conceived as a safe, affordable means of making hyperbaric oxygen therapy (HBOT) available in the developing world for the treatment of a variety of medical conditions. Specifically, HBOT is highly-desired as a possibly curative treatment for Buruli Ulcer, an infectious condition that afflicts children in sub-Saharan Africa. HBOT is simply too expensive and too dangerous to implement in the developing world using standard equipment. The HHC technology changes the paradigm. The HHC differs from standard hyperbaric chambers in that the majority of its volume is filled with water which is pressurized by oxygen being supplied in the portion of the chamber containing the patient s head. This greatly reduces the amount of oxygen required to sustain a hyperbaric atmosphere, thereby making the system more safe and economical to operate. An effort was taken to develop an HHC system to apply HBOT to children that is simple and robust enough to support transport, assembly, maintenance and operation in developing countries. This paper details the concept for an HHC ventilation and pressurization system to provide controlled pressurization and adequate washout of carbon dioxide while the subject is enclosed in the confined space during the administration of the medical treatment. The concept took into consideration operational complexity, safety to the patient and operating personnel, and physiological considerations. The simple schematic, comprised of easily acquired commercial hardware

  9. An ion-responsive motif in the second transmembrane segment of rhodopsin-like receptors.

    PubMed

    Parker, M S; Wong, Y Y; Parker, S L

    2008-06-01

    A L(M)xxxD(N, E) motif (x=a non-ionic amino acid residue, most frequently A, S, L or F; small capitals indicating a minor representation) is found in the second transmembrane (tm2) segment of most G-protein coupling metazoan receptors of the rhodopsin family (Rh-GPCRs). Changes in signal transduction, agonist binding and receptor cycling are known for numerous receptors bearing evolved or experimentally introduced mutations in this tm2 motif, especially of its aspartate residue. The [Na(+)] sensitivity of the receptor-agonist interaction relates to this aspartate in a number of Rh-GPCRs. Native non-conservative mutations in the tm2 motif only rarely coincide with significant changes in two other ubiquitous features of the rhodopsin family, the seventh transmembrane N(D)PxxY(F) motif and the D(E)RY(W,F) or analogous sequence at the border of the third transmembrane helix and the second intracellular loop. Native tm2 mutations with Rh-GPCRs frequently result in constitutive signaling, and with visual opsins also in shifts to short-wavelength sensitivity. Substitution of a strongly basic residue for the tm2 aspartate in Taste-2 receptors could be connected to a lack of sodium sensing by these receptors. These properties could be consistent with ionic interactions, and even of ion transfer, that involve the tm2 motif. A decrease in cation sensing by this motif is usually connected to an enhanced constitutive interaction of the mutated receptors with cognate G- proteins, and also relates to both the constitutive and the overall activity of the short-wavelength opsins.

  10. Quantification of static magnetic field effects on radiotherapy ionization chambers

    NASA Astrophysics Data System (ADS)

    Agnew, J.; O’Grady, F.; Young, R.; Duane, S.; Budgell, G. J.

    2017-03-01

    Integrated magnetic resonance (MR) imaging and radiotherapy (RT) delivery machines are currently being developed, with some already in clinical use. It is anticipated that the strong magnetic field used in some MR-RT designs will have a significant impact on routine measurements of dose in the MR-linac performed using ionization chambers, which provide traceability back to a primary standard definition of dose. In particular, the presence of small air gaps around ionization chambers may introduce unacceptably high uncertainty into these measurements. In this study, we investigate and quantify the variation attributable to air gaps for several routinely-used cylindrical ionization chambers in a magnetic field, as well as the effect of the magnetic field alone on the response of the chambers. The measurements were performed in a Co-60 beam, while the ionization chambers were positioned in custom-made Perspex phantoms between the poles of an electromagnet, which was capable of generating magnetic fields of up to 2 T field strength, although measurements were focused around 1.5 T. When an asymmetric air gap was rotated at cardinal angles around the ionization chambers investigated here, variation of up to 8.5  ±  0.2 percentage points (PTW 31006 chamber) was observed in an applied magnetic field of 1.5 T. The minimum peak-to-peak variation was 1.1  ±  0.1% (Exradin A1SL). When the same experiment was performed with a well-defined air gap of known position using the PTW 30013 chamber, a variation of 3.8  ±  0.2% was observed. When water was added to the phantom cavity to eliminate all air gaps, the variation for the PTW 30013 was reduced to 0.2  ±  0.01%.

  11. Quantification of static magnetic field effects on radiotherapy ionization chambers.

    PubMed

    Agnew, J; O'Grady, F; Young, R; Duane, S; Budgell, G J

    2017-03-07

    Integrated magnetic resonance (MR) imaging and radiotherapy (RT) delivery machines are currently being developed, with some already in clinical use. It is anticipated that the strong magnetic field used in some MR-RT designs will have a significant impact on routine measurements of dose in the MR-linac performed using ionization chambers, which provide traceability back to a primary standard definition of dose. In particular, the presence of small air gaps around ionization chambers may introduce unacceptably high uncertainty into these measurements. In this study, we investigate and quantify the variation attributable to air gaps for several routinely-used cylindrical ionization chambers in a magnetic field, as well as the effect of the magnetic field alone on the response of the chambers. The measurements were performed in a Co-60 beam, while the ionization chambers were positioned in custom-made Perspex phantoms between the poles of an electromagnet, which was capable of generating magnetic fields of up to 2 T field strength, although measurements were focused around 1.5 T. When an asymmetric air gap was rotated at cardinal angles around the ionization chambers investigated here, variation of up to 8.5  ±  0.2 percentage points (PTW 31006 chamber) was observed in an applied magnetic field of 1.5 T. The minimum peak-to-peak variation was 1.1  ±  0.1% (Exradin A1SL). When the same experiment was performed with a well-defined air gap of known position using the PTW 30013 chamber, a variation of 3.8  ±  0.2% was observed. When water was added to the phantom cavity to eliminate all air gaps, the variation for the PTW 30013 was reduced to 0.2  ±  0.01%.

  12. SU-E-T-460: Impact of the LINAC Repetition Rate On a High-Resolution Liquid Ionization Chamber Array for Patient-Specific QA

    SciTech Connect

    Wang, S; Driewer, J; Zheng, D; Lei, Y; Zhang, Q; Zhu, X; Li, S; Enke, C; Zhou, S; Xu, B

    2015-06-15

    Purpose: The purpose of this study is to investigate the LINAC repetition-rate (dose-rate) dependence of OCTAVIUS 1000SRS liquid ionization chamber (LIC) array for patient specific QA of SRT plans delivered with flattening-filter-free (FFF) beams. Methods: 1) The repetition-rate dependence of 1000SRS was measured in a phantom constructed with 5-cm solid water above and below the array for build-up and backscatter. A 0.3cc calibrated ion chamber was also placed along the central axis 2.3cm below the center chamber of the array for normalizing LINAC output fluctuation. The signals from the center chamber of the array under different repetition rates in the range of 400–2400 MU/min for 6xFFF and 10xFFF beams on a Varian TrueBeamSTx LINAC, normalized by the independent chamber readings, were analyzed for the array response dependence on repetition rates. 2) Twelve Step-and-shoot IMRS QA plans (6xFFF and 10xFFF) were delivered to the array under different repetition rates for analysis and comparison. 3) The absolute doses measured by the center chamber were compared to measurements using an independent ionization chamber with the identical setup, taken as the gold standard. 4) The correction factors based on the actual delivery repetition rate were applied to the measurements, and the results were compared again to the gold standard. Results: 1) The 1000SRS array exhibited repetition-rate dependence for FFF beams, up to 5% for 6xFFF and 10% for 10xFFF; 2) The array showed clinically-acceptable repetition-rate dependence for regular flattened beams; 3) This repetition-rate dependence significantly affected the measurement accuracy, thereby affecting IMRS QA results; 4) By applying an empirical repetition-rate correction, the corrected measurements agreed better with the gold standard ion chamber measurements. Conclusion: OCTAVIUS 1000SRS LIC array exhibited considerable repetition-rate dependence for FFF beams, which will affect the accuracy of the absolute QA

  13. Ionisation chamber containing boron as a neutron detector in medical accelerator fields.

    PubMed

    Zielczynski, M; Gryzinski, M A; Golnik, N; Tulik, P

    2007-01-01

    A combination of the recombination principle of H(10) measurements with the use of the ionisation chambers containing boron has been presented, in order to increase the relative sensitivity of the chamber to neutrons by a factor close to the radiation quality factor of photoneutrons. Three types of the chambers were investigated. Two of them were filled with BF(3) and the third one contained electrodes covered with B(4)C. All the chambers were placed in paraffin moderators. The response of the chambers was investigated, depending on gas pressure and polarising voltage. The results showed that it was possible to obtain nearly the same response of the chamber to H(10) for photons and neutrons in a restricted energy range; however, further investigations are needed to make an optimum design.

  14. Identifying the Ion Channels Responsible for Signaling Gastro-Intestinal Based Pain

    PubMed Central

    Brierley, Stuart M.; Hughes, Patrick A.; Harrington, Andrea M.; Rychkov, Grigori Y.; Blackshaw, L. Ashley

    2010-01-01

    We are normally unaware of the complex signalling events which continuously occur within our internal organs. Most of us only become cognisant when sensations of hunger, fullness, urgency or gas arise. However, for patients with organic and functional bowel disorders pain is an unpleasant and often debilitating reminder. Furthermore, chronic pain still represents a large unmet need for clinical treatment. Consequently, chronic pain has a considerable economic impact on health care systems and the afflicted individuals. In order to address this need we must understand how symptoms are generated within the gut, the molecular pathways responsible for generating these signals and how this process changes in disease states. PMID:27713376

  15. A mercury flow meter for ion thruster testing. [response time, thermal sensitivity

    NASA Technical Reports Server (NTRS)

    Wilbur, P. J.

    1973-01-01

    The theory of operation of the thermal flow meter is presented, and a theoretical model is used to determine design parameters for a device capable of measuring mercury flows in the range of 0 to 5 gm/hr. Flow meter construction is described. Tests performed using a positive displacement mercury pump as well as those performed with the device in the feed line of an operating thruster are discussed. A flow meter response time of about a minute and a sensitivity of about 10 mv/gm/hr are demonstrated. Additional work to relieve a sensitivity of the device to variations in ambient temperature is indicated to improve its quantitative performance.

  16. Negative Ion Density Fronts

    SciTech Connect

    Igor Kaganovich

    2000-12-18

    Negative ions tend to stratify in electronegative plasmas with hot electrons (electron temperature Te much larger than ion temperature Ti, Te > Ti ). The boundary separating a plasma containing negative ions, and a plasma, without negative ions, is usually thin, so that the negative ion density falls rapidly to zero-forming a negative ion density front. We review theoretical, experimental and numerical results giving the spatio-temporal evolution of negative ion density fronts during plasma ignition, the steady state, and extinction (afterglow). During plasma ignition, negative ion fronts are the result of the break of smooth plasma density profiles during nonlinear convection. In a steady-state plasma, the fronts are boundary layers with steepening of ion density profiles due to nonlinear convection also. But during plasma extinction, the ion fronts are of a completely different nature. Negative ions diffuse freely in the plasma core (no convection), whereas the negative ion front propagates towards the chamber walls with a nearly constant velocity. The concept of fronts turns out to be very effective in analysis of plasma density profile evolution in strongly non-isothermal plasmas.

  17. Proteomic Analysis Implicates Dominant Alterations of RNA Metabolism and the Proteasome Pathway in the Cellular Response to Carbon-Ion Irradiation

    PubMed Central

    Xie, Da-Fei; Xie, Yi; Liu, Xiao-Dan; Wang, Qi; Sui, Li; Song, Man; Zhang, Hong; Zhou, Jianhua; Zhou, Ping-Kun

    2016-01-01

    Radiotherapy with heavy ions is considered advantageous compared to irradiation with photons due to the characteristics of the Braggs peak and the high linear energy transfer (LET) value. To understand the mechanisms of cellular responses to different LET values and dosages of heavy ion radiation, we analyzed the proteomic profiles of mouse embryo fibroblast MEF cells exposed to two doses from different LET values of heavy ion 12C. Total proteins were extracted from these cells and examined by Q Exactive with Liquid Chromatography (LC)—Electrospray Ionization (ESI) Tandem MS (MS/MS). Using bioinformatics approaches, differentially expressed proteins with 1.5 or 2.0-fold changes between different dosages of exposure were compared. With the higher the dosage and/or LET of ion irradiation, the worse response the cells were in terms of protein expression. For instance, compared to the control (0 Gy), 771 (20.2%) proteins in cells irradiated at 0.2 Gy of carbon-ion radiation with 12.6 keV/μm, 313 proteins (8.2%) in cells irradiated at 2 Gy of carbon-ion radiation with 12.6 keV/μm, and 243 proteins (6.4%) in cells irradiated at 2 Gy of carbon-ion radiation with 31.5 keV/μm exhibited changes of 1.5-fold or greater. Gene ontology (GO) analysis, Kyoto Encyclopedia of Genes and Genomes (KEGG) analysis, Munich Information Center for Protein Sequences (MIPS) analysis, and BioCarta analysis all indicated that RNA metabolic processes (RNA splicing, destabilization and deadenylation) and proteasome pathways may play key roles in the cellular response to heavy-ion irradiation. Proteasome pathways ranked highest among all biological processes associated with heavy carbon-ion irradiation. In addition, network analysis revealed that cellular pathways involving proteins such as Col1a1 and Fn1 continued to respond to high dosages of heavy-ion irradiation, suggesting that these pathways still protect cells against damage. However, pathways such as those involving Ikbkg1 responded

  18. Membrane Modulates Affinity for Calcium Ion to Create an Apparent Cooperative Binding Response by Annexin a5

    PubMed Central

    Gauer, Jacob W.; Knutson, Kristofer J.; Jaworski, Samantha R.; Rice, Anne M.; Rannikko, Anika M.; Lentz, Barry R.; Hinderliter, Anne

    2013-01-01

    Isothermal titration calorimetry was used to characterize the binding of calcium ion (Ca2+) and phospholipid to the peripheral membrane-binding protein annexin a5. The phospholipid was a binary mixture of a neutral and an acidic phospholipid, specifically phosphatidylcholine and phosphatidylserine in the form of large unilamellar vesicles. To stringently define the mode of binding, a global fit of data collected in the presence and absence of membrane concentrations exceeding protein saturation was performed. A partition function defined the contribution of all heat-evolving or heat-absorbing binding states. We find that annexin a5 binds Ca2+ in solution according to a simple independent-site model (solution-state affinity). In the presence of phosphatidylserine-containing liposomes, binding of Ca2+ differentiates into two classes of sites, both of which have higher affinity compared with the solution-state affinity. As in the solution-state scenario, the sites within each class were described with an independent-site model. Transitioning from a solution state with lower Ca2+ affinity to a membrane-associated, higher Ca2+ affinity state, results in cooperative binding. We discuss how weak membrane association of annexin a5 prior to Ca2+ influx is the basis for the cooperative response of annexin a5 toward Ca2+, and the role of membrane organization in this response. PMID:23746516

  19. ION PRODUCING MECHANISMS

    DOEpatents

    Brobeck, W.M.

    1959-02-10

    Ion generating means and means for producing ions of material for isotopic separation are discussed. One feature of the invention resides in providing a heater means located in the source block approximately equidistant from a charge reservoir and an arc chamber, whereby the heat distribution in the block is such as to avoid overheating and to maintain the temperature of the various critical localities of the unit at their optimum values. Another feature consists of a pair of plates disposed on either side of the arc chamber exit opening to define a narrow slit for the egression of the ion beam. When the adjacent edges of the plates have become worn, the plates may be detached and reversed to use the opposite edges thereof to define the exit opening.

  20. Multiple Osmotic Stress Responses in Acidihalobacter prosperus Result in Tolerance to Chloride Ions.

    PubMed

    Dopson, Mark; Holmes, David S; Lazcano, Marcelo; McCredden, Timothy J; Bryan, Christopher G; Mulroney, Kieran T; Steuart, Robert; Jackaman, Connie; Watkin, Elizabeth L J

    2016-01-01

    Extremely acidophilic microorganisms (pH optima for growth of ≤3) are utilized for the extraction of metals from sulfide minerals in the industrial biotechnology of "biomining." A long term goal for biomining has been development of microbial consortia able to withstand increased chloride concentrations for use in regions where freshwater is scarce. However, when challenged by elevated salt, acidophiles experience both osmotic stress and an acidification of the cytoplasm due to a collapse of the inside positive membrane potential, leading to an influx of protons. In this study, we tested the ability of the halotolerant acidophile Acidihalobacter prosperus to grow and catalyze sulfide mineral dissolution in elevated concentrations of salt and identified chloride tolerance mechanisms in Ac. prosperus as well as the chloride susceptible species, Acidithiobacillus ferrooxidans. Ac. prosperus had optimum iron oxidation at 20 g L(-1) NaCl while At. ferrooxidans iron oxidation was inhibited in the presence of 6 g L(-1) NaCl. The tolerance to chloride in Ac. prosperus was consistent with electron microscopy, determination of cell viability, and bioleaching capability. The Ac. prosperus proteomic response to elevated chloride concentrations included the production of osmotic stress regulators that potentially induced production of the compatible solute, ectoine uptake protein, and increased iron oxidation resulting in heightened electron flow to drive proton export by the F0F1 ATPase. In contrast, At. ferrooxidans responded to low levels of Cl(-) with a generalized stress response, decreased iron oxidation, and an increase in central carbon metabolism. One potential adaptation to high chloride in the Ac. prosperus Rus protein involved in ferrous iron oxidation was an increase in the negativity of the surface potential of Rus Form I (and Form II) that could help explain how it can be active under elevated chloride concentrations. These data have been used to create a model

  1. Multiple Osmotic Stress Responses in Acidihalobacter prosperus Result in Tolerance to Chloride Ions

    PubMed Central

    Dopson, Mark; Holmes, David S.; Lazcano, Marcelo; McCredden, Timothy J.; Bryan, Christopher G.; Mulroney, Kieran T.; Steuart, Robert; Jackaman, Connie; Watkin, Elizabeth L. J.

    2017-01-01

    Extremely acidophilic microorganisms (pH optima for growth of ≤3) are utilized for the extraction of metals from sulfide minerals in the industrial biotechnology of “biomining.” A long term goal for biomining has been development of microbial consortia able to withstand increased chloride concentrations for use in regions where freshwater is scarce. However, when challenged by elevated salt, acidophiles experience both osmotic stress and an acidification of the cytoplasm due to a collapse of the inside positive membrane potential, leading to an influx of protons. In this study, we tested the ability of the halotolerant acidophile Acidihalobacter prosperus to grow and catalyze sulfide mineral dissolution in elevated concentrations of salt and identified chloride tolerance mechanisms in Ac. prosperus as well as the chloride susceptible species, Acidithiobacillus ferrooxidans. Ac. prosperus had optimum iron oxidation at 20 g L−1 NaCl while At. ferrooxidans iron oxidation was inhibited in the presence of 6 g L−1 NaCl. The tolerance to chloride in Ac. prosperus was consistent with electron microscopy, determination of cell viability, and bioleaching capability. The Ac. prosperus proteomic response to elevated chloride concentrations included the production of osmotic stress regulators that potentially induced production of the compatible solute, ectoine uptake protein, and increased iron oxidation resulting in heightened electron flow to drive proton export by the F0F1 ATPase. In contrast, At. ferrooxidans responded to low levels of Cl− with a generalized stress response, decreased iron oxidation, and an increase in central carbon metabolism. One potential adaptation to high chloride in the Ac. prosperus Rus protein involved in ferrous iron oxidation was an increase in the negativity of the surface potential of Rus Form I (and Form II) that could help explain how it can be active under elevated chloride concentrations. These data have been used to create a

  2. Integrated Chamber Design for the Laser Inertial Fusion Energy (LIFE) Engine

    SciTech Connect

    Latkowski, J F; Kramer, K J; Abbott, R P; Morris, K R; DeMuth, J; Divol, L; El-Dasher, B; Lafuente, A; Loosmore, G; Reyes, S; Moses, G A; Fratoni, M; Flowers, D; Aceves, S; Rhodes, M; Kane, J; Scott, H; Kramer, R; Pantano, C; Scullard, C; Sawicki, R; Wilks, S; Mehl, M

    2010-12-07

    The Laser Inertial Fusion Energy (LIFE) concept is being designed to operate as either a pure fusion or hybrid fusion-fission system. A key component of a LIFE engine is the fusion chamber subsystem. The present work details the chamber design for the pure fusion option. The fusion chamber consists of the first wall and blanket. This integrated system must absorb the fusion energy, produce fusion fuel to replace that burned in previous targets, and enable both target and laser beam transport to the ignition point. The chamber system also must mitigate target emissions, including ions, x-rays and neutrons and reset itself to enable operation at 10-15 Hz. Finally, the chamber must offer a high level of availability, which implies both a reasonable lifetime and the ability to rapidly replace damaged components. An integrated LIFE design that meets all of these requirements is described herein.

  3. Hydrogen hollow cathode ion source

    NASA Technical Reports Server (NTRS)

    Mirtich, M. J., Jr.; Sovey, J. S.; Roman, R. F. (Inventor)

    1980-01-01

    A source of hydrogen ions is disclosed and includes a chamber having at one end a cathode which provides electrons and through which hydrogen gas flows into the chamber. Screen and accelerator grids are provided at the other end of the chamber. A baffle plate is disposed between the cathode and the grids and a cylindrical baffle is disposed coaxially with the cathode at the one end of the chamber. The cylindrical baffle is of greater diameter than the baffle plate to provide discharge impedance and also to protect the cathode from ion flux. An anode electrode draws the electrons away from the cathode. The hollow cathode includes a tubular insert of tungsten impregnated with a low work function material to provide ample electrons. A heater is provided around the hollow cathode to initiate electron emission from the low work function material.

  4. Zymosan-induced immune challenge modifies the stress response of hypoxic air-breathing fish (Anabas testudineus Bloch): Evidence for reversed patterns of cortisol and thyroid hormone interaction, differential ion transporter functions and non-specific immune response.

    PubMed

    Simi, S; Peter, Valsa S; Peter, M C Subhash

    2016-11-18

    Fishes have evolved physiological mechanisms to exhibit stress response, where hormonal signals interact with an array of ion transporters and regulate homeostasis. As major ion transport regulators in fish, cortisol and thyroid hormones have been shown to interact and fine-tune the stress response. Likewise, in fishes many interactions have been identified between stress and immune components, but the physiological basis of such interaction has not yet delineated particularly in air-breathing fish. We, therefore, investigated the responses of thyroid hormones and cortisol, ion transporter functions and non-specific immune response of an obligate air-breathing fish Anabas testudineus Bloch to zymosan treatment or hypoxia stress or both, to understand how immune challenge modifies the pattern of stress response in this fish. Induction of experimental peritonitis in these fish by zymosan treatment (200ngg(-1)) for 24h produced rise in respiratory burst and lysozomal activities in head kidney phagocytes. In contrast, hypoxia stress for 30min in immune-challenged fish reversed these non-specific responses of head kidney phagocytes. The decline in plasma cortisol in zymosan-treated fish and its further suppression by hypoxia stress indicate that immune challenge suppresses the cortisol-driven stress response of this fish. Likewise, the decline in plasma T3 and T4 after zymosan-treatment and the rise in plasma T4 after hypoxia stress in immune-challenged fish indicate a critical role for thyroid hormone in immune-stress response due to its differential sensitivity to both immune and stress challenges. Further, analysis of the activity pattern of ion-dependent ATPases viz. Na(+)/K(+)-ATPase, H(+)/K(+)-ATPase and Na(+)/NH4(+)-ATPase indicates a functional interaction of ion transport system with the immune response as evident in its differential and spatial modifications after hypoxia stress in immune-challenged fish. The immune-challenge that produced differential pattern

  5. Single wire drift chamber design

    SciTech Connect

    Krider, J.

    1987-03-30

    This report summarizes the design and prototype tests of single wire drift chambers to be used in Fermilab test beam lines. The goal is to build simple, reliable detectors which require a minimum of electronics. Spatial resolution should match the 300 ..mu..m rms resolution of the 1 mm proportional chambers that they will replace. The detectors will be used in beams with particle rates up to 20 KHz. Single track efficiency should be at least 99%. The first application will be in the MT beamline, which has been designed for calibration of CDF detectors. A set of four x-y modules will be used to track and measure the momentum of beam particles.

  6. A pixel chamber to monitor the beam performances in hadron therapy

    NASA Astrophysics Data System (ADS)

    Bonin, R.; Boriano, A.; Bourhaleb, F.; Cirio, R.; Donetti, M.; Garelli, E.; Giordanengo, S.; Marchetto, F.; Peroni, C.; Sanz Freire, C. J.; Simonetti, L.

    2004-03-01

    In this paper we describe the design, construction, and tests of a parallel plate ionization chamber with the anode segmented in (32×32) square pixels. The performance of the read out and data acquisition systems is also discussed. The design of the chamber has been finalized to be used as a beam monitor for therapeutical treatments. Position and flux resolution obtained with a carbon ion beam are presented.

  7. 21 CFR 868.5470 - Hyperbaric chamber.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... than atmospheric pressure. This device does not include topical oxygen chambers for extremities (§ 878... hyperbaric chamber is a device that is intended to increase the environmental oxygen pressure to promote...

  8. Space Chambers for Crop Treatment

    NASA Technical Reports Server (NTRS)

    1985-01-01

    Vacuum chambers, operated by McDonnell Douglas Corporation to test spacecraft, can also be used to dry water-soaked records. The drying temperature is low enough to allow paper to dry without curling or charging. Agricultural crops may also be dried using a spinoff system called MIVAC, which has proven effective in drying rice, wheat, soybeans, corn, etc. The system is energy efficient and can incorporate a sanitation process for destroying insects without contamination.

  9. Intermingled modulatory and neurotoxic effects of thimerosal and mercuric ions on electrophysiological responses to GABA and NMDA in hippocampal neurons.

    PubMed

    Wyrembek, P; Szczuraszek, K; Majewska, M D; Mozrzymas, J W

    2010-12-01

    The organomercurial, thimerosal, is at the center of medical controversy as a suspected factor contributing to neurodevelopmental disorders in children. Many neurotoxic effects of thimerosal have been described, but its interaction with principal excitatory and inhibitory neurotransmiter systems is not known. We examined, using electrophysiological recordings, thimerosal effects on GABA and NMDA-evoked currents in cultured hippocampal neurons. After brief (3 to 10 min) exposure to thimerosal at concentrations up to 100 μM, there was no significant effect on GABA or NMDA-evoked currents. However, following exposure for 60-90 min to 1 or 10 μM thimerosal, there was a significant decrease in NMDA-induced currents (p<0.05) and GABAergic currents (p<0.05). Thimerosal was also neurotoxic, damaging a significant proportion of neurons after 60-90 min exposure; recordings were always conducted in the healthiest looking neurons. Mercuric chloride, at concentrations 1 μM and above, was even more toxic, killing a large proportion of cells after just a few minutes of exposure. Recordings from a few sturdy cells revealed that micromolar mercuric chloride markedly potentiated the GABAergic currents (p<0.05), but reduced NMDA-evoked currents (p<0.05). The results reveal complex interactions of thimerosal and mercuric ions with the GABA(A) and NMDA receptors. Mercuric chloride act rapidly, decreasing electrophysiological responses to NMDA but enhancing responses to GABA, while thimerosal works slowly, reducing both NMDA and GABA responses. The neurotoxic effects of both mercurials are interwoven with their modulatory actions on GABA(A) and NMDA receptors, which most likely involve binding to these macromolecules.

  10. Responsive Hydrogels and Ion Gels by Self-Assembly of ABA and ABC Triblock Polymers

    NASA Astrophysics Data System (ADS)

    Lodge, Timothy

    2014-03-01

    Gels - polymeric networks swollen with a substantial amount of solvent - represent a fascinating class of soft materials, with wide-ranging applications in fields as diverse as biomedicine, pharmaceutics, personal care products, foods, sensors, actuators, flexible electronics, oil recovery, and adhesives. Physical gels are held together by non-covalent interactions, which may be as specific as hydrogen bonds, or as general as solvophobic association of insoluble blocks. Among the attractive features of physical gels are reversibility, stimuli-responsiveness, and tunability of macroscopic properties. In this talk two classes of physical gels will be highlighted. In one, the ability of ABC block terpolymers to form novel structures will be demonstrated, where blocks A and C are mutually immiscible and solvophobic, while B is solvophilic. In particular, the formation of gels by sequential association (first A, then C) leads to a remarkably sharp gelation transition, at a relatively low polymer concentration, compared to analogous gels formed from ABA systems. In the second class, gels formed by self-assembly of a variety of ABA systems in ionic liquids will be described, and in particular how gelation can be controlled through factors such as block chemistry, temperature, choice of ionic liquid, and application of light.

  11. The crop growth research chamber

    NASA Technical Reports Server (NTRS)

    Wagenbach, Kimberly

    1993-01-01

    The Crop Growth Research Chamber (CGRC) has been defined by CELSS principle investigators and science advisory panels as a necessary ground-based tool in the development of a regenerative life support system. The focus of CGRC research will be on the biomass production component of the CELSS system. The ground-based Crop Growth Research Chamber is for the study of plant growth and development under stringently controlled environments isolated from the external environment. The chamber has importance in three areas of CELSS activities: (1) crop research; (2) system control and integration, and (3) flight hardware design and experimentation. The laboratory size of the CGRC will be small enough to allow duplication of the unit, the conducting of controlled experiments, and replication of experiments, but large enough to provide information representative of larger plant communities. Experiments will focus on plant growth in a wide variety of environments and the effects of those environments on plant production of food, water, oxygen, toxins, and microbes. To study these effects in a closed system, tight control of the environment is necessary.

  12. Rocket Engine Thrust Chamber Assembly

    NASA Technical Reports Server (NTRS)

    Cornelius, Charles S. (Inventor); Counts, Richard H. (Inventor); Myers, W. Neill (Inventor); Lackey, Jeffrey D. (Inventor); Peters, Warren (Inventor); Shadoan, Michael (Inventor); Sparks, David L. (Inventor); Lawrence, Timothy W. (Inventor)

    2001-01-01

    A thrust chamber assembly for liquid fueled rocket engines and the method of making it wherein a two-piece mandrel having the configuration of an assembly having a combustion chamber portion connected to a nozzle portion through a throat portion is wrapped with a silica tape saturated with a phenolic resin, the tape extending along the mandrel and covering the combustion chamber portion of the mandrel to the throat portion. The width of the tape is positioned at an angle of 30 to 50 deg. to the axis of the mandrel such that one edge of the tape contacts the mandrel while the other edge is spaced from the mandrel. The phenolic in the tape is cured and the end of the wrap is machined to provide a frusto-conical surface extending at an angle of 15 to 30 deg. with respect to the axis of the mandrel for starting a second wrap on the mandrel to cover the throat portion. The remainder of the mandrel is wrapped with a third silica tape having its width positioned at a angle of 5 to 20 deg. from the axis of the mandrel. The resin in the third tape is cured and the assembly is machined to provide a smooth outer surface. The entire assembly is then wrapped with a tow of graphite fibers wetted with an epoxy resin and, after the epoxy resin is cured, the graphite is machined to final dimensions.

  13. Designing an oscillating CO2 concentration experiment for fild chambers

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Questions have arisen about photosynthetic response to fluctuating carbon dioxide (CO2), which might affect yield in free-air CO2 enrichment (FACE) systems and in open top chambers. A few studies have been conducted based on CO2 controlled to cycles of fixed time-periods and fixed, large amplitude....

  14. Designing an oscillating CO2 concentration experiment for field chambers

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Questions have arisen about photosynthetic response to fluctuating carbon dioxide (CO2), which might affect yield in free-air CO2 enrichment (FACE) systems and in open top chambers. A few studies have been conducted based on CO2 controlled to cycles of fixed time-periods and fixed, large amplitude....

  15. IMPROVED ION-PRODUCING MECHANISM FOR CALUTRONS

    DOEpatents

    Bell, W.A. Jr.; Prater, W.K.

    1963-12-24

    An ion source for electromagnetically operated equipment for the separation of isotopes, such as the Calutron, wherein a unitized construction is employed to house both the arc chamber and the oven chamber to facilitate assembly and maintenance and to improve operation. ( LAMBDA EC)

  16. Ion cyclotron resonance cell

    DOEpatents

    Weller, Robert R.

    1995-01-01

    An ion cyclotron resonance cell having two adjacent sections separated by a center trapping plate. The first section is defined by the center trapping plate, a first end trapping plate, and excitation and detector electrodes. The second section includes a second end trapping plate spaced apart from the center plate, a mirror, and an analyzer. The analyzer includes a wavelength-selective light detector, such as a detector incorporating an acousto-optical device (AOD) and a photodetector. One or more ion guides, grounded plates with holes for the ion beam, are positioned within the vacuum chamber of the mass spectrometer between the ion source and the cell. After ions are trapped and analyzed by ion cyclotron resonance techniques in the first section, the ions of interest are selected according to their mass and passed into the second section for optical spectroscopic studies. The trapped ions are excited by light from a laser and caused thereby to fluoresce. The fluorescent light emitted by the excited ions is reflected by the mirror and directed onto the detector. The AOD is scanned, and the photodetector output is recorded and analyzed. The ions remain in the second section for an extended period, enabling multiple studies to be carried out on the same ensemble of ions.

  17. Ion cyclotron resonance cell

    DOEpatents

    Weller, R.R.

    1995-02-14

    An ion cyclotron resonance cell is disclosed having two adjacent sections separated by a center trapping plate. The first section is defined by the center trapping plate, a first end trapping plate, and excitation and detector electrodes. The second section includes a second end trapping plate spaced apart from the center plate, a mirror, and an analyzer. The analyzer includes a wavelength-selective light detector, such as a detector incorporating an acousto-optical device (AOD) and a photodetector. One or more ion guides, grounded plates with holes for the ion beam, are positioned within the vacuum chamber of the mass spectrometer between the ion source and the cell. After ions are trapped and analyzed by ion cyclotron resonance techniques in the first section, the ions of interest are selected according to their mass and passed into the second section for optical spectroscopic studies. The trapped ions are excited by light from a laser and caused thereby to fluoresce. The fluorescent light emitted by the excited ions is reflected by the mirror and directed onto the detector. The AOD is scanned, and the photodetector output is recorded and analyzed. The ions remain in the second section for an extended period, enabling multiple studies to be carried out on the same ensemble of ions. 5 figs.

  18. NSTAR Extended Life Test Discharge Chamber Flake Analysis

    NASA Technical Reports Server (NTRS)

    deGroh, Kim K.; Banks, Bruce A.; Karniotis, Christina A.

    2005-01-01

    The Extended Life Test (ELT) of the NASA Solar Electric Propulsion Technology Readiness (NSTAR) ion thruster was concluded after 30,352 hours of operation. The ELT was conducted using the Deep Space 1 (DS1) back-up flight engine, a 30 cm diameter xenon ion thruster. Post-test inspection of the ELT engine revealed numerous contaminant flakes distributed over the bottom of the cylindrical section of the anode within the discharge chamber (DC). Extensive analyses were conducted to determine the source of the particles, which is critical to the understanding of degradation mechanisms of long life ion thruster operation. Analyses included: optical microscopy (OM) and particle length histograms, field emission scanning electron microscopy (FESEM) combined with energy dispersive spectroscopy (EDS), and atomic oxygen plasma exposure tests. Analyses of the particles indicate that the majority of the DC flakes consist of a layered structure, typically with either two or three layers. The flakes comprising two layers were typically found to have a molybdenum-rich (Mo-rich) layer on one side and a carbon-rich (C-rich) layer on the other side. The flakes comprising three layers were found to be sandwich-like structures with Mo-rich exterior layers and a C-rich interior layer. The presence of the C-rich layers indicates that these particles were produced by sputter deposition build-up on a surface external to the discharge chamber from ion sputter erosion of the graphite target in the test chamber. This contaminant layer became thick enough that particles spalled off, and then were electro-statically attracted into the ion thruster interior, where they were coated with Mo from internal sputter erosion of the screen grid and cathode components. Atomic oxygen tests provided evidence that the DC chamber flakes are composed of a significant fraction of carbon. Particle size histograms further indicated that the source of the particles was spalling of carbon flakes from downstream

  19. Influence of chamber dimensions on the performance of a conduction micropump

    NASA Astrophysics Data System (ADS)

    Feng, Junyuan; Wan, Zhenping; Wen, Wanyu; Li, Yaochao; Tang, Yong

    2016-05-01

    An electrohydrodynamic (EHD) conduction micropump with symmetric planar electrodes is developed to investigate the effect of micropump chamber dimensions on static pressure and flow rate. The interdigitated electrodes are created on an FR-4 CCL (copper clad laminate) using photolithography. The micropump consists of an electrode plate, chamber plate, top and bottom end cover. A 2D numerical simulation study is conducted to provide details about the ion distribution and fluid flow behaviors within a local domain of micropumps with different chamber height. Experimental results show that, by increasing chamber height, the static pressure and flow rate rise with a big slope under a chamber height of 0.2 mm, and henceforth decrease dramatically. The variation trends of static pressure and flow rate with an increase in chamber height are determined by the combination of ion concentration distribution and fluidic circulation formed between the two electrodes. Additionally, the effect of the chamber width and length is experimentally analyzed for optimum pressure and output flow rate.

  20. Simulation of RF power and multi-cusp magnetic field requirement for H- ion sources

    NASA Astrophysics Data System (ADS)

    Pathak, Manish; Senecha, V. K.; Kumar, Rajnish; Ghodke, Dharmraj. V.

    2016-12-01

    A computer simulation study for multi-cusp RF based H- ion source has been carried out using energy and particle balance equation for inductively coupled uniformly dense plasma considering sheath formation near the boundary wall of the plasma chamber for RF ion source used as high current injector for 1 Gev H- Linac project for SNS applications. The average reaction rates for different reactions responsible for H- ion production and destruction have been considered in the simulation model. The RF power requirement for the caesium free H- ion source for a maximum possible H- ion beam current has been derived by evaluating the required current and RF voltage fed to the coil antenna using transformer model for Inductively Coupled Plasma (ICP). Different parameters of RF based H- ion source like excited hydrogen molecular density, H- ion density, RF voltage and current of RF antenna have been calculated through simulations in the presence and absence of multicusp magnetic field to distinctly observe the effect of multicusp field. The RF power evaluated for different H- ion current values have been compared with the experimental reported results showing reasonably good agreement considering the fact that some RF power will be reflected from the plasma medium. The results obtained have helped in understanding the optimum field strength and field free regions suitable for volume emission based H- ion sources. The compact RF ion source exhibits nearly 6 times better efficiency compare to large diameter ion source.