MC3: Novel Particle Sources and Acceleration Techniques
A15 New Acceleration Techniques
Paper Title Page
Overview of Low Energy Spread Laser Proton Accelerators  
  • X.Q. Yan
    PKU, Beijing, People’s Republic of China
  Laser-driven ion acceleration is a frontier of laser plasma physics which has been developed in recent decades. Energetic ion beam generation in the interaction of laser and matter has unique properties such as high brilliance, compact size, ultrashort duration, and low emittance. These advantages are particularly suitable for many potential applications. The ion acceleration methods like TNSA, RPA and shock acceleration are discussed here. The theories and experiments for monoenergetic proton/ion beams are reviewed in this talk. If laser acceleration is combined with a fully functional beam line, realizing precise manipulation of the proton beams, availability, maintainability and inspectability (RAMI), which paves the way for applications, such as proton therapy, diagnosis of plasma magnetic field (LITP), proton imaging, warm dense matter and so on.  
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Toward High Power Efficiency and High Gradient Dielectric Assist Accelerating Structures  
  • D. Satoh, R. Kuroda, H. Toyokawa
    AIST, Tsukuba, Ibaraki, Japan
  • S. Mori, M. Yoshida
    KEK, Ibaraki, Japan
  A dielectric assist accelerating (DAA) structure, a type of dielectric loaded accelerating structures, is greatly superior in power efficiency compared with the conventional disk-loaded copper structures. The advantage of DAA structure is that it has an extremely high quality (Q0 > 105) factor and a high shunt impedance (Zsh > 600 MOhm/m) at room temperature since the electromagnetic field distribution of the accelerating mode can be controlled by the geometry of its structure to reduce the wall loss on metallic surface. However, in a prototype of a DAA structure, multipactor discharge occurred between the ceramic cells, and high gradient operation has not been achieved. In order to solve this issue while maintaining the high-power efficiency of DAA structure, we have been studying ceramic materials and the surface coating so as to reduce the secondary electron emission coefficient. The structural optimization of the DAA structure for high gradient operation is examined by the cavity simulations. In this conference, the latest results of the simulation study and the experiments of DAA structure are reported.  
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Terahertz-Driven Acceleration of a Relativistic Electron Beam  
  • M.T. Hibberd, V. Georgiadis, D.M. Graham
    The University of Manchester, The Photon Science Institute, Manchester, United Kingdom
  • R.B. Appleby, E.J.H. Smith
    UMAN, Manchester, United Kingdom
  • G. Burt, O.J. Finlay, A.L. Healy, S.P. Jamison, D. Lake
    Cockcroft Institute, Lancaster University, Lancaster, United Kingdom
  • J.K. Jones, T.H. Pacey, Y.M. Saveliev, E.W. Snedden, D.A. Walsh
    STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom
  Funding: Science and Technology Facilities Council (STFC)
Terahertz (THz) pulses are emerging as unique driving sources for next-generation particle accelerators, offering unprecedented control over the energy-time phase-space of a particle bunch compared with conventional radio-frequency technology. Acceleration, compression and streaking have all been demonstrated with low energy electrons* but operation at relativistic energies remains limited. Here, we report on the first demonstration of phase-velocity matched acceleration of a relativistic electron beam in a THz-driven linear accelerator**, confirmed through frequency-tuning of the THz source. Operating in the highest beam energy (35 MeV) and charge (60 pC) regimes reported to date, we use narrowband THz pulses centered at 0.4 THz to drive collinear THz-electron interaction in a dielectric-lined waveguide. We exploit multi-cycle energy modulation of a chirped 6 ps electron bunch to extract the often-inaccessible longitudinal phase-space distribution, highlighting the potential for THz-driven bunch diagnostics. We also show injection-time-dependent preferential energy gain/loss for 2 ps bunches, demonstrating a route to whole-bunch acceleration of sub-ps relativistic electron beams.
*D. Zhang et al. Nat. Photonics 12, 336 (2018).
**M.T. Hibberd et al. arXiv:1908.04055.
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