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388 results on '"Phipps C"'

3. Pulsed Laser Interactions with Space Debris: Target Shape Effects

Author

Liedahl, D. A., Rubenchik, A., Libby, S. B., Nikolaev, S., and Phipps, C. R.

Subjects
Physics - Space Physics
Abstract

Among the approaches to the proposed mitigation and remediation of the space debris problem is the de-orbiting of objects in low Earth orbit through irradiation by ground-based high-intensity pulsed lasers. Laser ablation of a thin surface layer causes target recoil, resulting in the depletion of orbital angular momentum and accelerated atmospheric re-entry. However, both the magnitude and direction of the recoil are shape dependent, a feature of the laser-based remediation concept that has received little attention. Since the development of a predictive capability is desirable, we have investigated the dynamical response to ablation of objects comprising a variety of shapes. We derive and demonstrate a simple analytical technique for calculating the ablation-driven transfer of linear momentum, emphasizing cases for which the recoil is not exclusively parallel to the incident beam. For the purposes of comparison and contrast, we examine one case of momentum transfer in the low-intensity regime, where photon pressure is the dominant momentum transfer mechanism, showing that shape and orientation effects influence the target response in a similar, but not identical, manner. We address the related problem of target spin and, by way of a few simple examples, show how ablation can alter the spin state of a target, which often has a pronounced effect on the recoil dynamics., Comment: 51 pages, 14 figures, to appear in Advances in Space Research

Published
2013
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4. Evaluation of Bacillus clausii CSI08, Bacillus megaterium MIT411 and a Bacillus cocktail on gastrointestinal health: a randomised, double-blind, placebo-controlled pilot study

Author

Rea, K., primary, Colom, J., additional, Simon, E. A., additional, Khokhlova, E., additional, Mazhar, S., additional, Barrena, M., additional, Enrique, M., additional, Martorell, P., additional, Perez, B. Alvarez, additional, Tortajada, M., additional, Phipps, C., additional, and Deaton, J., additional

Published
2023
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11. Laser impulse coupling measurements at 400 fs and 80 ps using the LULI facility at 1057 nm wavelength.

Author

Phipps, C. R., Boustie, M., Chevalier, J.-M., Baton, S., Brambrink, E., Berthe, L., Schneider, M., Videau, L., Boyer, S. A. E., and Scharring, S.

Subjects
*PULSED lasers, *LASER ablation, *POLYOXYMETHYLENE, *SPACE debris, *DOPPLER velocimetry, *PHOTONICS
Abstract

At the École Polytechnique « LULI » facility, we have measured the impulse coupling coefficient Cm (target momentum per joule of incident laser light) with several target materials in vacuum, at 1057 nm and 400 fs and 80 ps pulse duration. A total of 64 laser shots were completed in a two-week experimental campaign, divided between the two pulse durations and among the materials. Our main purpose was to resolve wide discrepancies among reported values for Cm in the 100 ps region, where many applications exist. A secondary purpose was to compare Cm at 400 fs and 80 ps pulse duration. The 80 ps pulse was obtained by partial compression. Materials were Al, Ta, W, Au, and POM (polyoxymethylene, trade name Delrin). One application of these results is to pulsed laser ablation propulsion in space, including space debris re-entry, where narrow ranges in Cm and specific impulse Isp spell the difference between dramatic and uneconomical performance. We had difficulty measuring mass loss from single shots. Imparted momentum in single laser shots was determined using pendulum deflection and photonic Doppler velocimetry. Cm was smaller at the 400 fs pulse duration than at 80 ps. To our surprise, Cm for Al at 80 ps was at most 30 N/MW with 30 kJ/m² incident fluence. On the other extreme, polyoxymethylene (POM, trade name Delrin) demonstrated 770 N/MW under these conditions. Together, these results offer the possibility of designing a Cm value suited to an application, by mixing the materials appropriately. [ABSTRACT FROM AUTHOR]

Published
2017
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25. Rail heating analysis for multishot EM gun operation

Author

Fish, S., Phipps, C., and Tang, V.

Subjects
Weapons systems -- Evaluation, Missile launchers -- Evaluation, Business, Electronics, Electronics and electrical industries
Abstract

This paper describes a method o f analyzing potential railgun concepts for their rail heating effects in multishot mode. The method is meant to provide a quick estimate of heating effects based on the geometry of the rails and containment and the performance specifications of each shot. First, a coupled electrical-mechanical simulation is run for the railgun in which the effects of current diffusion are included to calculate the effective rail resistance and associated heating as a function of axial position and time. This analysis is then expanded with an assumed current distribution (relative amount of current on top and back of rail compared with the front) to develop a first order temperature distribution in the rail cross section at any specified axial location. This axial section is then subjected to two-dimensional finite element analysis (FEA) to determine the heat redistribution between shots. A sample set of calculations is compared with a single shot experiment incorporating temperature probes in the rails. Finally, the utility of the method for multishot analysis is shown with two simulations, one with and one without active cooling in the rails. Index Terms - cooling, heating, railguns, thermal.

Published
1999

32. Operation Wallacea - Cusuco National Park, Honduras 2016 & 2017 : end of season report

Author

Gilroy, DL, Jones, S, Vulinec, K, Thompson, P, Hoskins, H, Creedy, T, Jocque, M, Green, S, Lonsdale, G, Phipps, C, Burdekin, O, and Brown, T

Abstract

This end of season report is submitted as a review of the summer 2016-2017 seasons and the research\ud activities of the Operation Wallacea research teams in Cusuco National Park over the course of the two\ud summers. This report contains a summary of the methodologies and surveys employed, in addition to the\ud data collected during that time, and a complete analysis of that data as part of this complete report. A more\ud detailed analysis of the herpetofauana dataset, coving the period 2007-2017, is provided, as this\ud information was absent from more recent reports.

Published
2017

35. KOTTABISTAE

Author

Lyte, Henry Francis, Phipps, C. B., von Chamisso, A., Maguinness, W. S., Porter, W. H., Jones, Robert, Moore, T., Tate, R. W., Sedley, C., and Housman, A. E.

Published
1951

36. KOTTABISTAE

Author

Richepin, Jean, Maguinness, W. S., Tobias, T. C., Nash, Ogden, Johnston, J., Russell, Arthur Tozer, Phipps, C. B., and Bridge, J. J. R.

Published
1946

37. KOTTABISTAE

Author

Phipps, C. B., Harington, J., St. C. Brown, E., Tate, R. W., Campbell, T., du Bellay, Joachim, Maguinness, W. S., and Johnston, J.

Published
1946

38. KOTTABISTAE

Author

St. C. Brown, E., de la Mare, Walter, Poots, S. J., Tate, R. W., Richter, Jean Paul, Hitchock, F. R. M., How, William Walsham, and Phipps, C. B.

Published
1947

39. KOTTABISTAE

Author

Tate, R. W., Pedler, Margaret, Trench, Herbert, Phipps, C. B., and Hitchcock, F. R. M.

Published
1942

40. KOTTABISTAE

Author

Keble, J., Phipps, C. B., Neale, J. M., Hitchcock, F. R. M., Etherege, George, Jones, T. S., St. C. Brown, E., Maguinness, W. S., Spring-Rice, Cecil, Tate, R. W., and Bonar, H.

Published
1945

41. KOTTABISTAE

Author

Tate, R. W., Tobias, H. M., Chesterton, G. K., Tobias, T. C., Fletcher, John, St. C. Brown, E., Alexander, Cecil Frances, Phipps, C. B., and Bailey, P. J.

Published
1945

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