Introduction of Bisecting GlcNAc into Integrin α5β1 Reduces Ligand Binding and Down-regulates Cell Adhesion and Cell Migration

This research was originally published in the Journal of Biological Chemistry. Tomoya Isaji, Jianguo Gu, Ryoko Nishiuchi, Yanyang Zhao, Motoko Takahashi, Eiji Miyoshi, Koichi Honke, Kiyotoshi Sekiguchi and Naoyuki Taniguchi. Introduction of Bisecting GlcNAc into Integrin α5β1 Reduces Ligand Binding and Down-regulates Cell Adhesion and Cell Migration. J. Biol. Chem. 2004; 279: 19747-19754 © the American Society for Biochemistry and Molecular Biolog

Experimental investigation on temporal contrast of pre-pulses by post-pulses in a petawatt laser facility

We experimentally explore the generation of pre-pulses by post-pulses, created through internal reflection in the optical components, by the non-linear process associated with the B-integral in the laser chain of the petawatt facility J-KAREN-P. At large time delay between the main and the post-pulses, we have found that the pre-pulses are not generated from their counterpart post-pulses at an identical time difference before the main pulse and the temporal shapes of the pre-pulses are greatly distorted asymmetrically. We have also observed the peak intensities of the pre-pulses are drastically suppressed compared to the expected value at small time delay. We briefly describe the origins of the pre-pulses generated by the post-pulses and demonstrate the removal of the pre-pulses by switching to optical components with a small wedge angle at our petawatt laser facility

Enhancement of pre-pulse and picosecond pedestal contrast of the petawatt J-KAREN-P laser

We have experimentally improved the temporal contrast of the petawatt J-KAREN-P laser facility. We have investigated how the generation of pre-pulses by post-pulses changes due to the temporal overlap between the stretched pulse and the post-pulse in a chirped-pulse amplification system. We have shown that the time at which the pre-pulse by the post-pulse generates and its shape are related to the time difference between the stretched main-pulse and the post-pulse. With this investigation, we have found and identified the origins of the pre-pulses and have demonstrated removal of most pre-pulses by eliminating the post-pulse with wedged optics. We have also demonstrated the impact of stretcher optics on the picosecond pedestal. We have realized orders of magnitude enhancement of the pedestal by improving the optical quality of a key component in the stretcher

UV Harmonic Generation and Laser-Driven Proton Acceleration from Thin-Foil Target

UV harmonics and protons are observed with a high-intensity Ti:sapphire laser. High-energy protons are generated with an aluminum thin-foil target. Simultaneously with the high-energy protons the generation of third- and fourth- order harmonics are observed in the reflection direction by using a high-intensity high-contrast laser

Vieraea. Vol. 35

State-of-the-art high power laser facilities present numerous potential applications, including the generation of ultra-short and low emittance ion beams. Understanding the underlying laser-plasma interaction physics and resulting scaling to ultra-high intensities is of great importance for optimising such sources. We therefore present experimental data of proton acceleration in a sheath field using the ultra-high intensity J-KAREN-P laser (10 J, 40 fs, 5x1021 W/cm2), allowing investigation at the high-intensity frontier.A repetitive tape target was used to generate proton beams at a 0.1 Hz repetition rate limited only by the laser, allowing a systematic and comprehensive scan over laser parameters. Our laser-target system is able to regularly produce protons in excess of 40 MeV at the full repetition rate. We will demonstrate a slower than expected increase in proton energy with decreasing focal spot size, show that this is due to a reduced sheath lifetime for tight focal spots, and propose a new model which successfully predicts proton energies over a large range of focal spot sizes.We demonstrate that the laser accelerated electron temperature depends not only on laser intensity but also on focal-spot size, in which the restriction of the transverse acceleration distance causes saturation of the electron temperature at increasingly small foci. However, the accelerated electron beam profile becomes more collimated and asymmetric with small focal spots. Measurements of the proton beam show only limited benefit to using increasingly small focal spot sizes, and the best scaling for achieving higher maximum proton energies from sheath acceleration is achieved with increasing the pulse energy, rather than reducing the spot size or pulse length.Optics & Photonics International Congress 2019 (HEDS2019

Electron heating and ion acceleration in sheaths from ultra-high intensity laser-solid interactions

The behaviour of high power laser-plasma interaction from solid targets, and the resultant ion generation, at the extreme intensities available at state-of-the-art laser facilities is an important topic for realising potential applications. We will present experimental data investigating electron heating and proton acceleration in a sheath field using the ultra-high intensity, high contrast J- KAREN-P laser. Using a 10 J, 40 fs pulse focused to an intensity ~5x1021 Wcm-2 resulted in generation of protons up to 40 MeV at 0.1 Hz from a 5 μm steel tape target. The high repetition rate of the tape target allowed large statistically relevant investigations into the scaling of the electron and proton beam with laser energy, pulse length and spot size.We demonstrate that the laser accelerated electron temperature depends not only on laser intensity but also on focal-spot size, in which the restriction of the transverse acceleration distance causes saturation of the electron temperature at increasingly small foci. However, the accelerated electron beam profile becomes more collimated and asymmetric with small focal spots. Measurements of the proton beam show only limited benefit to using increasingly small focal spot sizes, and the best scaling for achieving higher maximum proton energies from sheath acceleration is achieved with increasing the pulse energy, rather than reducing the spot size or pulse length.Imperial College London Plasma Physics Group Semina

Experimental investigation of sheath- driven proton acceleration scaling to the ultra-short pulse, ultra-high intensity regime

The behaviour of high power laser-plasma interaction from solid targets, and the resultant ion generation, at the extreme intensities available at state-of-the-art laser facilities is an important topic for realising potential applications. We will present experimental data investigating electron heating and proton acceleration in a sheath field using the ultra-high intensity, high contrast J- KAREN-P laser. Using a 10 J, 40 fs pulse focused to an intensity ~5x1021 Wcm-2 resulted in generation of protons up to 40 MeV at 0.1 Hz from a 5 μm steel tape target. The high repetition rate of the tape target allowed large statistically relevant investigations into the scaling of the electron and proton beam with laser energy, pulse length and spot size.We demonstrate that the laser accelerated electron temperature depends not only on laser intensity but also on focal-spot size, in which the restriction of the transverse acceleration distance causes saturation of the electron temperature at increasingly small foci. However, the accelerated electron beam profile becomes more collimated and asymmetric with small focal spots. Measurements of the proton beam show only limited benefit to using increasingly small focal spot sizes, and the best scaling for achieving higher maximum proton energies from sheath acceleration is achieved with increasing the pulse energy, rather than reducing the spot size or pulse length.JPS butsuri gakka