Author: Ryu, W.J.
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TUP079 Laser Wakefield Acceleration by using a Laser Produced Aluminium Plasma 543
  • J. Kim, Y.H. Hwangbo, S.G. Jeon
    KERI, Changwon, Republic of Korea
  • K.N. Kim, S. H. Park, W.J. Ryu, N. Vinokurov
    KAERI, Daejon, Republic of Korea
  In laser wakefield accelerator, usually a gas target is used to generate plasma medium. With this gas target, the pressure of the system cannot be keep as low as possible for electron beam application such as seeding the storage ring. To reduce this vacuum problem in LWFA, a plasma generated from solid Al target was used as plasma medium. A fundamental beam from the Q-switched ns pump laser in the Ti:sapphire power amplifier was used to generate a plasma from solid Al target. The plasma density was controlled by changing the distance between the main laser pulse for electron acceleration and the solid target. The plasma density was measured by the interferometer. The measured density indicates that the average charge of the ion in pre-plasma was 4.4. The main pulse ionized the Al plasma up to Al XII which means that the ionization injection could be used as an injection scheme. A 28 TW fs laser was used to accelerate the electron. A quasi-monochromatic electron was generated. The peak energy was 70 MeV and energy spread was 15 %. The divergence of the beam was 12 mrad in horizontal direction and 6 mrad in vertical direction.  
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WEP082 High-Power Ultrashort Terahertz Pulses generated by a Multi-foil Radiator with Laser-Accelerated Electron Pulses 739
  • J.S. Jo, B.A. Gudkov, Y.U. Jeong, H.N. Kim, K.N. Kim, K. Lee, S.V. Miginsky, S. H. Park, W.J. Ryu, N. Vinokurov
    KAERI, Daejon, Republic of Korea
  • B.A. Gudkov, S.V. Miginsky, N. Vinokurov
    BINP SB RAS, Novosibirsk, Russia
  Terahertz (THz) wave is an attractive source for a variety of research including imaging, spectroscopy, security, etc. We proposed a new scheme of high-power and ultrashort THz generation by using the coherent transition radiation from a cone-shaped multi-foil radiator [*] and a rectangle-shaped multi-foil radiator. To perform the proof-of-principle of the multi-foil THz radiator, we used 80~100 MeV electron bunches from laser-plasma acceleration. While a cone-shaped multi-foil radiator has a circular polarization with a conic wave, we made a rectangle-shaped multi-foil radiator that has a linear polarization in a plane-like wave, which can be used more widely for various applications. We can easily control the power of multi-foil radiator by adjusting the number of foils. We compare the THz power ratio between 1 sheet and multi sheets using cooled bolometer. We will measure the pulse duration and bandwidth of the THz wave from the multi-foil radiators in a single-shot by using electro-optic sampling and cross-correlation method.
* Phys. Rev. Lett. 110, 064805.
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