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Journal Articles

Strong flux pinning by columnar defects with directionally dependent morphologies in GdBCO-coated conductors irradiated with 80 MeV Xe ions

Sueyoshi, Tetsuro*; Kotaki, Tetsuya*; Furuki, Yuichi*; Fujiyoshi, Takanori*; Semboshi, Satoshi*; Ozaki, Toshinori*; Sakane, Hitoshi*; Kudo, Masaki*; Yasuda, Kazuhiro*; Ishikawa, Norito

Japanese Journal of Applied Physics, 59(2), p.023001_1 - 023001_7, 2020/02

 Times Cited Count:1 Percentile:52.74(Physics, Applied)

We show that Xe ion irradiation with 80 MeV to GdBa$$_{2}$$Cu$$_{3}$$Oy-coated conductors creates different morphologies of columnar defects (CDs) depending on the irradiation angles relative to the c-axis: continuous CDs with a larger diameter are formed for oblique irradiation at $$theta_{rm i}$$ = 45$$^{circ}$$, whereas the same ion beam at a different angle ($$theta_{rm i}$$ = 0$$^{circ}$$) induces the formation of discontinuous CDs. The direction-dependent morphologies of CDs significantly affect the angular behavior of the critical current density $$J_{rm c}$$.

Journal Articles

Flux pinning properties in YBCO films with growth-controlled nano-dots and heavy-ion irradiation defects

Sueyoshi, Tetsuro*; Kotaki, Tetsuya*; Uraguchi, Yusei*; Suenaga, Momotaro*; Makihara, Takahiro*; Fujiyoshi, Takanori*; Ishikawa, Norito

Physica C, 530, p.72 - 75, 2016/11

 Times Cited Count:5 Percentile:65.32(Physics, Applied)

In order to clarify the influence of size and spatial distribution of three-dimensional pinning centers (3D-PCs) on hybrid flux pinning, columnar defects (CDs) were installed by using 200 MeV Xe ions along the $$c$$-axis direction into quasi-multilayered films consisting of YBa$$_{2}$$Cu$$_{3}$$Oy layers and pseudo layers of BaSnO$$_{3}$$. The positive effect of the BaSnO$$_{3}$$ doping on the hybrid flux pinning stands out for the critical current density $$J_{rm c}$$ around $$B parallel c$$ in high magnetic field and/or inclined magnetic field off the $$c$$-axis, whereas there is little difference in the $$J_{rm c}$$ at $$B parallel c$$ among the same growth temperature samples for low magnetic field. In the case of the in-plane distributed BaSnO$$_{3}$$ nano-dots, the Jc around $$B parallel ab$$ is remarkably enhanced, whereas there is a detrimental effect on the Jc around $$B parallel c$$. These imply that the tuning of 3D-PCs is one of the keys to improve the $$J_{rm c}$$ at all magnetic field orientations for the hybrid flux pinning.

Journal Articles

Revealing the second harmonic generation in a femtosecond laser-driven cluster-based plasma by analyzing shapes of Ar XVII spectral lines

Oks, E.*; Dalimier, E.*; Faenov, A.*; Pikuz, T.*; Fukuda, Yuji; Andreev, A.*; Koga, J. K.; Sakaki, Hironao; Kotaki, Hideyuki; Pirozhkov, A. S.; et al.

Optics Express (Internet), 23(25), p.31991 - 32005, 2015/12

 Times Cited Count:6 Percentile:57.32(Optics)

We present experiments dealing with a femtosecond laser-driven cluster-based plasma, where by analyzing the nonlinear phenomenon of satellites of spectral lines of Ar XVII, we revealed the nonlinear phenomenon of the generation of the second harmonic of the laser frequency. For performing this analysis we developed new results in the theory of satellites of spectral lines. From such lineshape analysis we found, in particular, that the efficiency of converting the short (40 fs) intense (3$$times$$10$$^{18}$$ W/cm$$^2$$) incident laser light into the second harmonic was 2%. This result is in the excellent agreement with the 2-Dimensional Particle-In-Cell (2D PIC) simulation that we also performed. There is also an order of magnitude agreement between the thresholds for the SHG found from the line shape analysis and from the 2D PIC simulations.

Journal Articles

Influence of discontinuous columnar defects on flux pinning properties in GdBCO coated conductors

Sueyoshi, Tetsuro*; Kotaki, Tetsuya*; Furuki, Yuichi*; Uraguchi, Yusei*; Kai, Takashi*; Fujiyoshi, Takanori*; Shimada, Yusuke*; Yasuda, Kazuhiro*; Ishikawa, Norito

IEEE Transactions on Applied Superconductivity, 25(3), p.6603004_1 - 6603004_4, 2015/06

 Times Cited Count:6 Percentile:58(Engineering, Electrical & Electronic)

To investigate the effect of discontinuity of 1-D pinning centers on the flux pinning in a wide range of magnetic field directions, discontinuous columnar defects (CDs) and continuous CDs were formed in GdBCO coated conductors using Xe-ion irradiations with 80 and 270 MeV, respectively. An overall shift upward in Jc, for the 80-MeV-irradiated sample compared to the 270-MeV-irradiated one, can be observed in every direction of magnetic field, which is more remarkable as temperature decreases. This implies a synergetic effect of the pinning interaction between the linearity and the discontinuity for the discontinuous CDs.

Journal Articles

High order harmonics from relativistic electron spikes

Pirozhkov, A. S.; Kando, Masaki; Esirkepov, T. Z.; Faenov, A. Y.*; Pikuz, T. A.*; Kawachi, Tetsuya; Sagisaka, Akito; Koga, J. K.; Mori, Michiaki; Kawase, Keigo*; et al.

RAL-TR-2015-025, P. 22, 2015/00

Journal Articles

High order harmonics from relativistic electron spikes

Pirozhkov, A. S.; Kando, Masaki; Esirkepov, T. Z.; Gallegos, P.*; Ahmed, H.*; Ragozin, E. N.*; Faenov, A. Ya.*; Pikuz, T. A.*; Kawachi, Tetsuya; Sagisaka, Akito; et al.

New Journal of Physics (Internet), 16(9), p.093003_1 - 093003_30, 2014/09

 Times Cited Count:24 Percentile:18.16(Physics, Multidisciplinary)

Journal Articles

Angular dependence of critical current density and $$n$$-values in BaZrO$$_{3}$$/YBa$$_{2}$$Cu$$_{3}$$O$$_{y}$$ quasi-multilayered films with columnar defects

Sueyoshi, Tetsuro*; Kotaki, Tetsuya*; Fujiyoshi, Takanori*; Mitsugi, Fumiaki*; Ikegami, Tomoaki*; Ishikawa, Norito

Physica C, 494, p.153 - 157, 2013/11

 Times Cited Count:5 Percentile:70.57(Physics, Applied)

BaZrO$$_{3}$$/YBa$$_{2}$$Cu$$_{3}$$Oy quasi-multilayered films, in which the size and the spatial distribution of BaZrO$$_{3}$$ nano-particles were controlled, were irradiated using 200 MeV Xe ions along the c-axis direction. Whenthe BaZrO$$_{3}$$ nano-particles were larger in size, the flux lines not captured by CDs, such as interstitial fluxlines between CDs and double kinks of flux lines, can be pinned more effectively by the BaZrO$$_{3}$$ nano-particles, so that the Jc enhances for high magnetic fields and high temperature. In addition, the inverse correlation between Jc and n-value appears at high temperature in increasing magnetic field for the film with correlated rows of the nano-particles which might be curved off the c-axis. These suggest that the hybrid flux pinning depends not only on the combination of one-dimensional (1D) and three-dimensional pinning centers (3D-PCs) but also on the size and the spatial distribution of the 3D-PCs.

Journal Articles

Relativistic high harmonic generation in gas jet targets

Pirozhkov, A. S.; Kando, Masaki; Esirkepov, T. Z.; Gallegos, P.*; Ahmed, H.*; Ragozin, E. N.*; Faenov, A. Ya.*; Pikuz, T.; Kawachi, Tetsuya; Sagisaka, Akito; et al.

AIP Conference Proceedings 1465, p.167 - 171, 2012/07

 Times Cited Count:1 Percentile:49.7

Journal Articles

High-order harmonics from bow wave caustics driven by a high-intensity laser

Esirkepov, T. Z.; Pirozhkov, A. S.; Kando, Masaki; Gallegos, P.*; Ahmed, H.*; Ragozin, E. N.*; Faenov, A.*; Pikuz, T.; Kawachi, Tetsuya; Sagisaka, Akito; et al.

AIP Conference Proceedings 1465, p.172 - 180, 2012/07

 Times Cited Count:0 Percentile:100

The bow wave induced mechanism of high-order harmonics generation was discovered using simulations and catastrophe theory. This mechanism feasibility was successfully demonstrated in 3D and 2D PIC simulations. The mechanism and the simulations explained high-order harmonics in the XUV spectral region seen in recent experiments with terawatt lasers. Development of new XUV light and X-ray source based on the high-order harmonics generation mechanism is proposed.

Journal Articles

X-ray emission from relativistically moving electron density cusps

Kando, Masaki; Pirozhkov, A. S.; Nakamura, Tatsufumi; Hayashi, Yukio; Kotaki, Hideyuki; Kawase, Keigo*; Esirkepov, T. Z.; Fukuda, Yuji; Kiriyama, Hiromitsu; Okada, Hajime; et al.

AIP Conference Proceedings 1465, p.159 - 166, 2012/07

 Times Cited Count:0 Percentile:100

Journal Articles

Soft-X-ray harmonic comb from relativistic electron spikes

Pirozhkov, A. S.; Kando, Masaki; Esirkepov, T. Z.; Gallegos, P.*; Ahmed, H.*; Ragozin, E. N.*; Faenov, A. Ya.*; Pikuz, T.; Kawachi, Tetsuya; Sagisaka, Akito; et al.

Physical Review Letters, 108(13), p.135004_1 - 135004_5, 2012/03

 Times Cited Count:62 Percentile:8.09(Physics, Multidisciplinary)

We demonstrate a new high-order harmonic generation mechanism reaching the "water window" spectral region in experiments with multi-terawatt femtosecond lasers irradiating gas jets. A few hundred harmonic orders are resolved, giving $$mu$$J/sr pulses. Harmonics are collectively emitted by an oscillating electron spike formed at the joint of the boundaries of a cavity and bow wave created by a relativistically self-focusing laser in underdense plasma. The spike sharpness and stability are explained by catastrophe theory. The mechanism is corroborated by particle-in-cell simulations.

Journal Articles

Metrology of wide field of view nano-thickness foils' homogeneity by conventional and phase contrast soft X-ray imaging

Faenov, A. Y.; Pikuz, T.*; Fukuda, Yuji; Kando, Masaki; Kotaki, Hideyuki; Homma, Takayuki; Kawase, Keigo; Skobelev, I.*; Gasilov, S.*; Kawachi, Tetsuya; et al.

Japanese Journal of Applied Physics, 49(6), p.06GK03_1 - 06GK03_5, 2010/06

 Times Cited Count:8 Percentile:62.38(Physics, Applied)

Journal Articles

Enhancement of photon number reflected by the relativistic flying mirror

Kando, Masaki; Pirozhkov, A. S.; Kawase, Keigo; Esirkepov, T. Z.; Fukuda, Yuji; Kiriyama, Hiromitsu; Okada, Hajime; Daito, Izuru; Kameshima, Takashi; Hayashi, Yukio; et al.

Physical Review Letters, 103(23), p.235003_1 - 235003_4, 2009/12

 Times Cited Count:82 Percentile:6.53(Physics, Multidisciplinary)

Journal Articles

Experimental studies of the high and low frequency electromagnetic radiation produced from nonlinear laser-plasma interactions

Kando, Masaki; Pirozhkov, A. S.; Fukuda, Yuji; Esirkepov, T. Z.; Daito, Izuru; Kawase, Keigo; Ma, J. L.*; Chen, L. M.*; Hayashi, Yukio; Mori, Michiaki; et al.

European Physical Journal D, 55(2), p.465 - 474, 2009/09

 Times Cited Count:17 Percentile:34.2(Optics)

Nonlinear interaction of intense laser beams with plasma causes a number of different regimes of generation of high energy particle beams and of strong radiation with the emitted photon energy from the X-ray to THz frequency range. The review of the first proof-of-principle experiment and the latest progress on the flying mirror is presented. A low frequency EM radiation emission has also been observed in our experiments. The interpretation invokes the relativistic electromagnetic solitons. The solitons are formed in an underdense plasma in the process of the laser pulse frequency downshift. They store a portion of EM wave energy with the polarization inherited from the laser and emit it at the plasma-vacuum interface in a form of the low frequency EM bursts. We present the results of the polarization-resolved measurements.

Journal Articles

Demonstration of flying mirror with improved efficiency

Pirozhkov, A. S.; Kando, Masaki; Esirkepov, T. Z.; Fukuda, Yuji; Chen, L.-M.*; Daito, Izuru; Ogura, Koichi; Homma, Takayuki; Hayashi, Yukio; Kotaki, Hideyuki; et al.

AIP Conference Proceedings 1153, p.274 - 284, 2009/07

Journal Articles

Soft X-ray source for nanostructure imaging using femtosecond-laser-irradiated clusters

Fukuda, Yuji; Faenov, A. Y.; Pikuz, T. A.*; Kando, Masaki; Kotaki, Hideyuki; Daito, Izuru; Ma, J.-L.; Chen, L. M.; Homma, Takayuki; Kawase, Keigo; et al.

Applied Physics Letters, 92(12), p.121110_1 - 121110_3, 2008/03

 Times Cited Count:56 Percentile:11.58(Physics, Applied)

The novel soft X-ray light source using the supersonic expansion of the mixed gas of He and CO$$_2$$, when irradiated by a femtosecond Ti:sapphire laser pulse, is observed to enhance the radiation of soft X-rays from the CO$$_2$$ clusters. Using this soft X-ray emissions, nanostructure images of 100-nm thick Mo foils in a wide field of view (mm$$^2$$ scale) with high spatial resolution (800 nm) are obtained with high dynamic range LiF crystal detectors. The local inhomogeneities of soft X-ray absorption by the nanometer-thick foils is measured with an accuracy of less than $$pm$$ 3 %.

Journal Articles

Frequency multiplication of light back-reflected from a relativistic wake wave

Pirozhkov, A. S.; Ma, J.-L.; Kando, Masaki; Esirkepov, T. Z.; Fukuda, Yuji; Chen, L. M.; Daito, Izuru; Ogura, Koichi; Homma, Takayuki; Hayashi, Yukio; et al.

Physics of Plasmas, 14(12), p.123106_1 - 123106_22, 2007/12

 Times Cited Count:84 Percentile:52.63(Physics, Fluids & Plasmas)

Journal Articles

Experimental verification of laser photocathode RF gun as an injector for a laser plasma accelerator

Uesaka, Mitsuru*; Kinoshita, Kenichi*; Watanabe, Takahiro*; Sugahara, Jun*; Ueda, Toru*; Yoshii, Koji*; Kobayashi, Tetsuya*; Halz, N.*; Nakajima, Kazuhisa; Sakai, Fumio*; et al.

IEEE Transactions on Plasma Science, 28(4), p.1133 - 1142, 2000/08

 Times Cited Count:14 Percentile:56.1(Physics, Fluids & Plasmas)

no abstracts in English

Oral presentation

Relativistic flying mirror

Pirozhkov, A. S.; Kando, Masaki; Fukuda, Yuji; Ma, J.-L.; Esirkepov, T. Z.; Daito, Izuru; Chen, L. M.; Ogura, Koichi; Homma, Takayuki; Hayashi, Yukio; et al.

no journal, , 

Oral presentation

Relativistic tennis using flying mirror

Pirozhkov, A. S.; Kando, Masaki; Esirkepov, T. Z.; Ma, J.-L.; Fukuda, Yuji; Chen, L. M.; Daito, Izuru; Ogura, Koichi; Homma, Takayuki; Hayashi, Yukio; et al.

no journal, , 

50 (Records 1-20 displayed on this page)