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7,032 results on '"Morita, T"'

204. Collective Thomson scattering in non-equilibrium laser produced two-stream plasmas

Author

Sakai, K., primary, Isayama, S., additional, Bolouki, N., additional, Habibi, M. S., additional, Liu, Y. L., additional, Hsieh, Y. H., additional, Chu, H. H., additional, Wang, J., additional, Chen, S. H., additional, Morita, T., additional, Tomita, K., additional, Yamazaki, R., additional, Sakawa, Y., additional, Matsukiyo, S., additional, and Kuramitsu, Y., additional

Published
2020
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211. Transverse-junction-stripe GaAs-AlGaAs lasers for squeezed light generation

Author

Lathi, S., Tanaka, K., Morita, T., Inoue, S., Kan, H., and Yamamoto, Y.

Subjects
Semiconductor lasers -- Research, Gallium arsenide semiconductors -- Optical properties, Business, Computers, Electronics, Electronics and electrical industries
Abstract

An enhanced metal-organic chemical vapor deposition (MOCVD) and double Zn diffusion procedure were employed to construct 850-nm GaAs transverse-junction-stripe lasers. The high V/III ratio utilized during the MOCVD growth substantially decreased the intermixing of GaAs active layer and AlGaAs cladding layers. The modified procedure afforded good confinement for both carriers and photons, and smaller saturable loss.

Published
1999

222. Maser radiation from collisionless shocks

Author

Speirs, D. C., Ronald, K., Phelps, A. D. R., Koepke, M. E., Cairns, Robert Alan, Rigby, A., Cruz, F., Trines, R. M. G. M., Bamford, R., Kellet, B. J., Albertazzi, B., Cross, J. E., Fraschetti, F., Graham, P., Kozlowski, P. M., Kuramitsu, Y., Miniati, F., Morita, T., Oliver, M., Reville, B., Sakawa, Y., Sarkar, S., Spindloe, C., Koenig, M., Silva, L. O., Lamb, D. Q., Tzeferacos, P., Lebedev, S., Gregori, G., Bingham, R., EPSRC, and University of St Andrews. Applied Mathematics

Subjects
Laboratory astrophysics, QC Physics, Plasma-wave instabilities, Physics::Space Physics, Particle acceleration, T-NDAS, QB Astronomy, T Technology, QC, Plasma physics, QB
Abstract

Funding: UK Engineering and Physical Sciences Research Council (grant Nos. EP/N014472/1, EP/R004773/1 and EP/N013298/1) and the Science and Technologies Facilities Council of the United Kingdom. F.C. and L.O.S. acknowledge support from the European Research Council (InPairs ERC-2015-AdG 695088) and FCT Portugal (grant No. PD/BD/114307/2016). This paper describes a model of electron energization and cyclotron-maser emission applicable to astrophysical magnetized collisionless shocks. It is motivated by the work of Begelman, Ergun and Rees [Astrophys. J. 625 , 51 (2005)] who argued that the cyclotron-maser instability occurs in localized magnetized collisionless shocks such as those expected in blazar jets. We report on recent research carried out to investigate electron acceleration at collisionless shocks and maser radiation associated with the accelerated electrons. We describe how electrons accelerated by lower-hybrid,waves at collisionless shocks generate cyclotron-maser radiation when the accelerated electrons move into regions of stronger magnetic fields. The electrons are accelerated along the magnetic field and magnetically compressed leading to the formation of an electron velocity distribution having a horseshoe shape due to conservation of the electron magnetic moment. Under certain conditions the horseshoe electron velocity distribution function is unstable to the cyclotron-maser instability [Bingham and Cairns, Phys. Plasmas 7, 3089 (2000); Melrose, Rev. Mod. Plasma Phys. 1 , 5 (2017)]. Publisher PDF

Published
2019

227. A hybrid photodetector (HPD) with a III-V Photocathode

Author

Suyama, M., Hirano, K., Kawai, Y., Nagai, T., Kibune, A., Saito, T., Negi, Y., Asakura, N., Muramatsu, S., and Morita, T.

Subjects
Photodetectors -- Design and construction, Photoelectric devices -- Design and construction, Electron tubes -- Usage, Business, Electronics, Electronics and electrical industries
Abstract

A hybrid photodetector (HPD) combined with a III-V photocathode is considered to be an ideal photodetector, because the quantum efficiency (QE) is high, the collection efficiency is 100%, and the excess noise factor is negligible. An HPD combined with a GaAs photocathode or a blue enhanced GaAs (BE-GaAs) photocathode has been developed. Presently, the QE is approximately 20% from 550nm to 850nm, which is much higher than that of a conventional multi-alkali (S-20) photocathode. The 100% collection efficiency calculated by the computer simulation is supported by the test result of the flat uniformity. Considering the application in high energy physics using a wavelength shifter, energy resolutions of both the BE-GaAs-HPD and the conventional S20-HPD were measured using a 650nm LED light pulse. The BE-GaAs-HPD shows a resolution of 17%, as against 34% for the S20-HPD. The experimental results are consistent with the theoretical estimation. The QE of the HPD is especially important, because the electron multiplication process is noiseless.

Published
1998

231. Abstracts

Author

Rosemberg, S., Telxelra, M. J., Alves, V. A. F., Perry J. R., Ang L. C., Bilbao J. M., Muller P. J., Min, Kyung -Whan, Cashman, Robert, Brumback, Roger A., Rao, C., Deloso, D., Anderson, V., Seymour, A., Wrzolek, M., Abdu, A., Swanson, R., Honavar, M., Waters, K. B., Wise, S. M., Kubota, T., Sato, K., Kabuto, M., Nakagawa, T., Kitai, R., Nitta, H., Yamashita, J., Vital, C., Rivel, J., Sangalli, F., Benjelloun, B., Vital, A., Leger, F., Riemens, V., Epardeau, B., Guerin, J., Coindre, J. M., Ruchoux, M. M., Dhellemmes, P., Hamon, M., Lecomte, M., Hassoun, J., Yagishita, Saburo, Kawano, Nobuyuki, Kameya, Toru, Bowman, R., Liwnicz, B. H., Peckham, N., Barbosa-Coutinho, L. M., Hilbig, L. M., Hilbig, A., Loiseau, H., Mouton, L., Delisle, H. B., Rummens, C., Akai, F., Taneda, M., Iwasaki, H., Suzuki, Y., Tsanaclis, A. M. C., Aguiar, P. H. P., Logullo, A. F., Matamores, M. R., Yacubian, A., Komatsu, H., Oka, H., Suwa, T., Stoltenburg-Didinger, G., Gotzia, C., Benndorf, G., Kepes, J. J., Baba-Ahmed, R., Wong, K., Raisanen, J., Taylor, S. L., McDermott, M. W., Gutin, P., Havlioglu, Necat, Manepalli, Anantha, Galindo, Lorenzo, Sotelo-Avila, Cirilo, Grosso, Leonard, Kavavattathayyil, S., Chen, P., Wrzolek, M. A., Cook, J., Woodward, D. E., Tracqui, P., Cruywagen, G. C., Murray, J. D., Bartoo, G. T., Alvord, Jr., E. C., Szymas, Janusz, Jelonek, Jacek, Krawiec, Krzysztof, Slowinski, Roman, Coons, S. W., Johnson, P. C., Uro, E., Bousquet, P. H., Delisle, M. B., Rangueil, C. H. U., Torp, S. H., Johannesen, E., Lindboe, C. F., Beil, Michael, Kato, S., Morita, T., Kato, M., Herz, F., Hirano, A., Ohama, E., Albuquerque, L., Pimentel, J., Távora, L., Antunes, N. L., Weis, S., Protopapa, D., Mäerz, U., Winkler, P. A., Reulen, H. J., Mehraein, P., Di, Xiao, Reifenberger, Julia, Reifenberger, Guido, Liu, Lu, James, C. David, Wechsler, Wolfgang, Collins, V. Peter, McLendon, R. E., Batra, S. K., Friedman, H. S., Rasheed, B. K. A., Bigner, D. D., Bigner, S. K., Patt, S., Thiel, G., Labrousse, F., de Néchaud, B., Gomès, D., Daumas-Duport, C., Allarmargot, C., Dupouey, P., Vrionis, F., Qi, P., Cherington, V., Cano, G., Wu, J., Lampson, L. A., Chen, A., Vortmeyer, A. O., Slack, R. S., Skerjanc, I. S., Lach, B., Craig, J., Jardine, K., McBurney, M. W., Macaulay, R. J. B., Dimitroulakos, J., Becker, L. E., Yeger, H., Rhodes, C. Harker, Honsinger, Charles, Sorenson, George D., Goumnerova L. C., Segal R. A., Kwon Y. K., Stiles C. D., Pomeroy S. L., Guha, A., Lau, N., Pawson, A., Engel, Ute, Gutowski, Nick J., Bevan, Karen, Noble, Mark, Gladson, C. L., Pijuan, V., Olman, M. A., Gillespie, G. Y., Yacoub, I., Yamasaki, T., Enomoto, K., Moritake, K., Akiyama, Y., Kawahara, M., Maeno, T., Merzak, A., Parker, C., Koocheckpour, S., Sherbet, G. V., Pilkington, G. J., Martin, K., Akinwunmi, J., Rooprai, H. K., Kennedy, A., Linke, A., Ognjenovic, N., Fujiwara, T., Matsumoto, Y., Miyake, K., Shin, M., Nagao, S., Pulido-Cejudo, G., Jamison, K., Hugenholtz, H., Campione-Piccardo, J., Maidment, S. L., Lins, C., Takyia, C. M., Garcia-Abreu, J., Rodrigues, F. F., Duarte, F., Chagas, C., Chneiweiss, H., and Neto, V. Moura

Published
1995
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236. Experimental and fracture mechanics study of the pit formation mechanism under repeated lubricated rolling-sliding contact: effects of reversal of rotation and change of the driving roller

Author

Murakami, Y., Sakae, C., Ichimaru, K., and Morita, T.

Subjects
Fracture mechanics -- Analysis, Lubrication and lubricants -- Analysis, Rolling contact -- Analysis, Science and technology
Abstract

Five rolling contact fatigue tests, Tests {1}-{5} have been conducted. In Tests {1}{3}, when a fatigue crack was initiated on the surface of a follower, the test was halted. Then, in Test {1} the rotating direction was reversed. In Test {2} the follower and driver were interchanged, and in Test {3} the test was continued unchanged. In Test {3} the original crack grew to a pit. In Tests {1} and {2} the original crack immediately stopped propagating. In Tests {4} and {5}, mating with a harder roller, a softer roller was used as the follower in Test {4} and as the driver in Test {5}. A typical pit occurred in Test {4}. In Test {5}, surface damage substantially different from a typical pit was generated. Based on these experimental results, a 3-D crack analysis including the effect of frictional force on the contact surface and oil hydraulic pressure on crack surfaces, was conducted to elucidate the mechanisms of pit formation and surface damage in contact fatigue.

Published
1997

237. High Mach-number collisionless shock driven by a laser with an external magnetic field

Author

Morita T., Sakawa Y., Kuramitsu Y., Ide T., Nishio K., Kuwada M., Ide H., Tsubouchi K., Yoneda H., Nishida A., Namiki T., Norimatsu T., Tomita K., Nakayama K., Inoue K., Uchino K., Nakatsutsumi M., Pelka A., Koenig M., Dong Q., Yuan D., Gregori G., and Takabe H.

Subjects
Physics, QC1-999
Abstract

Collisionless shocks are produced in counter-streaming plasmas with an external magnetic field. The shocks are generated due to an electrostatic field generated in counter-streaming laser-irradiated plasmas, as reported previously in a series of experiments without an external magnetic field [T. Morita et al., Phys. Plasmas, 17, 122702 (2010), Kuramitsu et al., Phys. Rev. Lett., 106, 175002 (2011)] via laser-irradiation of a double-CH-foil target. A magnetic field is applied to the region between two foils by putting an electro-magnet (∼10 T) perpendicular to the direction of plasma expansion. The generated shocks show different characteristics later in time (t > 20ns).

Published
2013
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238. High-power laser experiments to study collisionless shock generation

Author

Sakawa Y., Kuramitsu Y., Morita T., Kato T., Tanji H., Ide T., Nishio K., Kuwada M., Tsubouchi T., Ide H., Norimatsu T., Gregory C., Woolsey N., Schaar K., Murphy C., Gregori G., Diziere A., Pelka A., Koenig M., Wang S., Dong Q., Li Y., Park H.-S., Ross S., Kugland N., Ryutov D., Remington B., Spitkovsky A., Froula D., and Takabe H.

Subjects
Physics, QC1-999
Abstract

A collisionless Weibel-instability mediated shock in a self-generated magnetic field is studied using two-dimensional particle-in-cell simulation [Kato and Takabe, Astophys. J. Lett. 681, L93 (2008)]. It is predicted that the generation of the Weibel shock requires to use NIF-class high-power laser system. Collisionless electrostatic shocks are produced in counter-streaming plasmas using Gekko XII laser system [Kuramitsu et al., Phys. Rev. Lett. 106, 175002 (2011)]. A NIF facility time proposal is approved to study the formation of the collisionless Weibel shock. OMEGA and OMEGA EP experiments have been started to study the plasma conditions of counter-streaming plasmas required for the NIF experiment using Thomson scattering and to develop proton radiography diagnostics.

Published
2013
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239. Laboratory experiments on plasma jets in a magnetic field using high-power lasers

Author

Nishio K., Sakawa Y., Kuramitsu Y., Morita T., Ide T., Kuwada M., Koga M., Kato T., Norimatsu T., Gregory C., Woolsey N., Murphy C., Gregori G., Schaar K., Diziere A., Koenig M., Pelka A., Wang S., Dong Q., Li Y., and Takabe H.

Subjects
Physics, QC1-999
Abstract

The experiments to simulate astrophysical jet generation are performed using Gekko XII (GXII) HIPER laser system at the Institute of Laser Engineering. In the experiments a fast plasma flow generated by shooting a CH plane (10 μm thickness) is observed at the rear side of the plane. By separating the focal spot of the main beams, a non-uniform plasma is generated. The non-uniform plasma flow in an external magnetic field (0.2∼0.3 T) perpendicular to the plasma is more collimated than that without the external magnetic field. The plasma β, the ratio between the plasma and magnetic pressure, is ≫ 1, and the magnetic Reynolds number is ∼150 in the collimated plasma. It is considered that the magnetic field is distorted by the plasma flow and enhances the jet collimation.

Published
2013
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240. Formation of counterstreaming plasmas for collisionless shock experiment

Author

Ide T., Sakawa Y., Kuramitsu Y., Morita T., Tanji H., Nishio K., Kuwada M., Ide H., Tsubouchi K., Shimazaki S., Taguchi T., Gregory C., Diziere A., Nakatsutsumi M., Koenig M., Ohnishi N., and Takabe H.

Subjects
Physics, QC1-999
Abstract

Process of counterstreaming plasma generation for laser irradiation of the innner-surface of the first plane of a double-plane target is investigated. The image taken by streaked self-emission optical pyrometer and radiation hydrodynamic simulation show the plasma from the second plane is ablated by radiation almost at the laser timing. After ∼5ns, increase in brightness and the generation of a plasma on the second plane are observed. According to the contemporary measurement of streaked interferometry, this is caused by the ablation of the second plane by the first plane plasma.

Published
2013
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241. A compact hybrid photodetector (HPD)

Author

Suyama, M., Kawai, Y., Kimura, S., Asakura, N., Hirano, K., Hasegawa, Y., Saito, T., Morita, T., Muramatsu, M., and Yamamoto, Kenichi

Subjects
Photodetectors -- Design and construction, Business, Electronics, Electronics and electrical industries
Abstract

In order to be utilized in such application fields as high energy physics or medical imaging, where a huge number of photodetectors are assembled in designated small area, the world's smallest hybrid photodetector (HPD), the compact HPD, has been developed. The overall diameter and the length of the tube are 16mm and 15mm, respectively. The effective photocathode area is 8mm in diameter. At applied voltage of -8kV to the photocathode, the electron multiplication gain of a PD incorporated HPD (PD-HPD) is 1,600, and that of an APD (APD-HPD) is 65,000. In the pulse height distribution measurement, photoelectron peaks up to 6 photoelectrons are clearly distinguishable with the APD-HPD. Experiments established that there was no degradation of gain in magnetic fields up to 1.5T, an important performance characteristic of the compact HPD for application in high energy physics.

Published
1997

249. The K2K SciBar detector

Author

Nitta, K., Aliu, E., Andringa, S., Aoki, S., Choi, S., Dore, U., Espinal, X., Gomez-Cadenas, J.J., Gran, R., Hasegawa, M., Hayashi, K., Hayato, Y., Hiraide, K., Ichikawa, A.K., Iinuma, M., Jang, J.S., Jeon, E.J., Joo, K.K., Jung, C.K., Kato, I., Kerr, D., Kim, J.Y., Kim, S.B., Kobayashi, K., Kohara, A., Kubota, J., Kudenko, Yu., Kuno, Y., Lee, M.J., Lessac-Chenin, E., Lim, I.T., Loverre, P.F., Ludovici, L., Maesaka, H., Mariani, C., McGrew, C., Mineev, O., Morita, T., Murakami, T., Nakanishi, Y., Nakaya, T., Nawang, S., Nishikawa, K., Pac, M.Y., Rhee, E.J., Rodríguez, A., Sanchez, F., Sasaki, T., Shiraishi, K.K., Suzuki, A., Takahashi, T., Takubo, Y., Tanaka, M., Terri, R., Tornero-Lopez, A., Ueda, S., Wilkes, R.J., Yamamoto, S., Yokoyama, M., and Yoshida, M.

Published
2004
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