Experimental study of fs electron bunch generation by laser plasma cathode

Plasmas irradiated by intense short laser pulses can be an efficient, compact, and flexible source of multi-MeV electrons constituting a bunchwith its duration in the femtosecond range. So we have studied a laser plasma cathode based on Laser Wake Field Acceleration (LWFA) with electron injection by wave-breaking, which is driven by a femtosecond intense laser pulse (Ti:Sapphire, max 12TW, lambda = 800nm , 50fs, 10Hz) tightly focused in supersonic helium gas-jet. The wave-breaking is the simplest way to inject energetic electrons into the wakes produced by an intense laser pulse. However, the wave-breaking requires a steep density plasmainterface with order of the plasma wavelength. According to our previous experiment, this condition can be produced via generation of a shock-wave in the gas jet by proper laser prepulse irradiation. It shows ejection of a narrow-cone MeV electron beam from a gas jet depend strongly on the prepulse contrast ratio. Furthermore, in case of higher gas density, the effect of laser prepulse become more sophisticate.The laser pulse is refracted at the edge of the cavity produced by the prepulse and thiseffect limit the narrow-cone MeV electron beam production of LWFA. In addition, I will also mention a narrow energy spread e-spectrum obtained in our recent experiment, development of a shockwave-free supersonic gas jet and gas filled capillary discharge wave-guide.11th Advanced Accelerator Concept 200

Particle-in-cell simulation on the mechanism and scalability of Terahertz Generation from atmosphere plasma ionized by two-color fs laser

大規模計算機システム利用者研究報

Facilities in Asia for future accelerator development

© 2022 IOP Publishing Ltd and Sissa Medialab.We introduce and review available and active research facilities that involve novel acceleration concepts in Asia. Most of the facilities equip with high-peak-power (>10 TW) lasers with tens of femtosecond duration for laser wakefield acceleration. The activities in Asia are growing and several problems on the realization of high energy frontier accelerators would be accessed through the existing facilities.11Nsciescopu

Experimental demonstration of 7-femtosecond electron timing fluctuation in laser wakefield acceleration

We report on an experimental investigation of the jitter of electrons from laser wakefield acceleration. The relative arrival timings of the generatedelectron bunches were detected via electro-optic spatial decoding on the coherent transition radiation emitted when the electrons pass through a100 μm thick stainless steel foil. The standard deviation of electron timing was measured to be 7 fs at a position outside the plasma. Preliminaryanalysis suggested that the electron bunches might have durations of a few tens of femtoseconds. This research demonstrated the potential oflaser wakefield acceleration for femtosecond pump–probe studies

Possibility for observing Hawking-like effects via the interaction of multi-PW class laser pulses with plasmas

The interaction of multi-PW laser pulses with underdense plasma, in the regime of strong relativistic wave-breaking, is investigated via fully relativistic 3D particle-in-cell simulations including ion motion and radiation reaction. The effect of a transverse cylindrical plasma wave in laser pulse wakes on the formation of regular electron bunches under extremely high acceleration suitable for detection of the Hawking-Unruh temperature is shown and analyzed.3rd Asia-Pacific Conference on Plasma Physic

Effects of Laser Peening with a Pulse Energy of 1.7 mJ on the Residual Stress and Fatigue Properties of A7075 Aluminum Alloy

Laser peening without coating (LPwC) using a palmtop-sized microchip laser has improved the residual stresses (RSs) and fatigue properties of A7075 aluminum alloy. Laser pulses with a wavelength of 1.06 μm and duration of 1.3 ns from a Q-switched Nd:YAG microchip laser were focused onto A7075 aluminum alloy samples covered with water. X-ray diffraction revealed compressive RSs on the surface after irradiation using laser pulses with an energy of 1.7 mJ, spot diameter of 0.3 mm, and density of 100–1600 pulse/mm2. The effects were evident to depths of a few hundred micrometers and the maximum compressive RS was close to the yield strength. Rotation-bending fatigue experiments revealed that LPwC with a pulse energy of 1.7 mJ significantly prolonged the fatigue life and increased the fatigue strength by about 100 MPa with 107 fatigue cycles. The microchip laser used in this study is small enough to fit in the hand or be mounted on a robot arm. The results may lead to the development of tools that extend the service life of various metal parts and structures, especially outdoors where conventional lasers are difficult to apply