With the stat-of-the-art laser technique, the quality of electron beam generated from LPA （laser-plasma accelerator） is now becoming much better. The natural merits of electron beam from LPA, e.g., high peak current...With the stat-of-the-art laser technique, the quality of electron beam generated from LPA （laser-plasma accelerator） is now becoming much better. The natural merits of electron beam from LPA, e.g., high peak current, ultra-low emittance and ultra-short bunch length, etc., pave the way to the novel light sources, especially in the realm of developing much more compact x-ray light sources, e.g., table-top XFEL （x-ray free-electron laser）. However, the radiation power is limited by the rather larger energy spread than conventional radio-frequency electron LINAC （linear accelerator）. Luckily, much more power could be extracted by using the undulator with transverse gradient when energy spread effect could be compensated. In this paper, we introduce a novel soit x-ray light source driven by LPA together with TGU （transverse gradient undulator） technique, meanwhile we present a simple idea on how to achieve much higher rep-rate （e.g., -100 kHz） FELs （free-electron lasers） boosted by TGU based on storage rings.展开更多
A new type of compact terahertz (THz) radiation source using free electron laser (FEL) is discussed in this paper.The concept machine consists of an independently tunable cell thermionic RF gun (ITC-RF Gun),an acceler...A new type of compact terahertz (THz) radiation source using free electron laser (FEL) is discussed in this paper.The concept machine consists of an independently tunable cell thermionic RF gun (ITC-RF Gun),an accelerating structure with symmetry RF-incoupler and a coaxial load RF-outcoupler,an undulator combined with an optical resonance cavity of hole-coupling mode.Withoutα-magnet and other bunch compressors,the size of this machine is decreased.The conceptual design and numerical simulation are presented.展开更多
In the solar system, our Sun is Nature's most efficient particle accelerator. In large solar flares and fast coronal mass ejections(CMEs), protons and heavy ions can be accelerated to over ~GeV/nucleon. Large flar...In the solar system, our Sun is Nature's most efficient particle accelerator. In large solar flares and fast coronal mass ejections(CMEs), protons and heavy ions can be accelerated to over ~GeV/nucleon. Large flares and fast CMEs often occur together. However there are clues that different acceleration mechanisms exist in these two processes. In solar flares, particles are accelerated at magnetic reconnection sites and stochastic acceleration likely dominates. In comparison, at CME-driven shocks,diffusive shock acceleration dominates. Besides solar flares and CMEs, which are transient events, acceleration of particles has also been observed in other places in the solar system, including the solar wind termination shock, planetary bow shocks, and shocks bounding the Corotation Interaction Regions(CIRs). Understanding how particles are accelerated in these places has been a central topic of space physics. However, because observations of energetic particles are often made at spacecraft near the Earth,propagation of energetic particles in the solar wind smears out many distinct features of the acceleration process. The propagation of a charged particle in the solar wind closely relates to the turbulent electric field and magnetic field of the solar wind through particle-wave interaction. A correct interpretation of the observations therefore requires a thorough understanding of the solar wind turbulence. Conversely, one can deduce properties of the solar wind turbulence from energetic particle observations. In this article I briefly review some of the current state of knowledge of particle acceleration and transport in the inner heliosphere and discuss a few topics which may bear the key features to further understand the problem of particle acceleration and transport.展开更多
基金The authors would like to thank Huang, Z., and Ding, Y. from SLAC and Feng, C., Deng, H., Lan, T., Shen, L., Wang, X. and Liu, B. from SINAP for helpful discussions. The authors are grateful for the support of Major State Basic Research Development Program of China （No. 2011CB808300）, and Natural Science Foundation of China （No. 11075199）.
文摘With the stat-of-the-art laser technique, the quality of electron beam generated from LPA （laser-plasma accelerator） is now becoming much better. The natural merits of electron beam from LPA, e.g., high peak current, ultra-low emittance and ultra-short bunch length, etc., pave the way to the novel light sources, especially in the realm of developing much more compact x-ray light sources, e.g., table-top XFEL （x-ray free-electron laser）. However, the radiation power is limited by the rather larger energy spread than conventional radio-frequency electron LINAC （linear accelerator）. Luckily, much more power could be extracted by using the undulator with transverse gradient when energy spread effect could be compensated. In this paper, we introduce a novel soit x-ray light source driven by LPA together with TGU （transverse gradient undulator） technique, meanwhile we present a simple idea on how to achieve much higher rep-rate （e.g., -100 kHz） FELs （free-electron lasers） boosted by TGU based on storage rings.
文摘A new type of compact terahertz (THz) radiation source using free electron laser (FEL) is discussed in this paper.The concept machine consists of an independently tunable cell thermionic RF gun (ITC-RF Gun),an accelerating structure with symmetry RF-incoupler and a coaxial load RF-outcoupler,an undulator combined with an optical resonance cavity of hole-coupling mode.Withoutα-magnet and other bunch compressors,the size of this machine is decreased.The conceptual design and numerical simulation are presented.
基金supported in part by a guest professorship grant from the School of Geophysics and Information Technology, China University of Geosciences (Beijing)
文摘In the solar system, our Sun is Nature's most efficient particle accelerator. In large solar flares and fast coronal mass ejections(CMEs), protons and heavy ions can be accelerated to over ~GeV/nucleon. Large flares and fast CMEs often occur together. However there are clues that different acceleration mechanisms exist in these two processes. In solar flares, particles are accelerated at magnetic reconnection sites and stochastic acceleration likely dominates. In comparison, at CME-driven shocks,diffusive shock acceleration dominates. Besides solar flares and CMEs, which are transient events, acceleration of particles has also been observed in other places in the solar system, including the solar wind termination shock, planetary bow shocks, and shocks bounding the Corotation Interaction Regions(CIRs). Understanding how particles are accelerated in these places has been a central topic of space physics. However, because observations of energetic particles are often made at spacecraft near the Earth,propagation of energetic particles in the solar wind smears out many distinct features of the acceleration process. The propagation of a charged particle in the solar wind closely relates to the turbulent electric field and magnetic field of the solar wind through particle-wave interaction. A correct interpretation of the observations therefore requires a thorough understanding of the solar wind turbulence. Conversely, one can deduce properties of the solar wind turbulence from energetic particle observations. In this article I briefly review some of the current state of knowledge of particle acceleration and transport in the inner heliosphere and discuss a few topics which may bear the key features to further understand the problem of particle acceleration and transport.
