This is because typical materials contain impurities, whose f-center can initiate sparks under a couple of orders of magnitude lower fields. But this happens more typically even under much lower field limit.
#View only tajima pulse free
Metallic electrons may be subject to hop out of the metallic chemical potential into a free (with breakdown) state typically the surface field on the order of MeV/cm. The single particle interaction with the externally imposed voltage on the metallic boundary suffers from the surface materials breakdown by sparks and arching. In this review we concentrate on the latter only. Here we contrast the nature of the individual force and acceleration based on this (and thus linear force and the conventional accelerators) with that of the collective force and acceleration based on the collective force. We summarize the cardinal differences between the individual and collective forces. Thus, collective fields (as opposed to the single particle interaction) are nonlinear. Collective accelerators based on the collective interaction involved a large number ( N) of particles, which give rise to fields that are collectively composed by these particles and those particles themselves interact with each other. Veksler suggested the idea of collective field acceleration in plasma (Veksler 1956), which triggered research in collective accelerators (Rostoker and Reiser 1979).
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The dynamics is determined foremost by each charge particle interacting with the external fields and this is the single particle dynamics. Meanwhile, we find evidence that the Mother Nature spontaneously created wakefields that accelerate electrons and ions to very high energies.Ĭonventional accelerators are by and large based on the single particle interaction of charged particles with the externally imposed accelerating fields (Chao et al. A new avenue of LWFA using nanomaterials is also emerging, adopting X-ray laser using the above TFC and RC. Applications such as ion acceleration, X-ray free electron laser, electron and ion cancer therapy are discussed. These in turn have created a conglomerate of novel science and technology with LWFA to form a new genre of high field science with many parameters of merit in this field increasing exponentially lately. The strong interest in this has driven novel laser technologies, including the Chirped Pulse Amplification, the Thin Film Compression (TFC), the Coherent Amplification Network, and the Relativistic Compression (RC). A large number of world-wide experiments show a rapid progress of this concept realization toward both the high energy accelerator prospect and broad applications. When we deploy laser ion acceleration or high density LWFA in which the phase velocity of plasma excitation is low, we encounter the sheath dynamics.
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When the phase velocity gets smaller, wakefields turn into sheaths. While the large amplitude of wakefields involves collective resonant oscillations of the eigenmode of the entire plasma electrons, the wake phase velocity ~ c and ultrafastness of the laser pulse introduce the wake stability and rigidity.
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The structures of wakes and sheaths in plasma are contrasted. An ultrafast intense laser pulse drives coherent wakefields of relativistic amplitude with the high phase velocity robustly supported by the plasma. The fundamental idea of Laser Wakefield Acceleration (LWFA) is reviewed.