| My thesis is mainly related to the collective behavior of the relativistic electrons in the hot plasma. We study the feasibility for the relativistic electron beam (REB) realizing fast ignition in the hot plasma produced by multi-path lasers focusing on the target. In addition, in order to attain table-top controllable nuclear fusion, we show theoretically that the feasibility for applying femto-second intense laser pulse realizing fast ignition to the pre-compressed hot bubble in an acoustic field.The thesis is organized as follows:(1) The collective behavior of the relativistic electrons in the hot plasma. At present, the collective behavior of the electrons in the plasma done by Pines and Bohm (1952) is generally accepted. They mainly studied the behavior of the electrons in a dense electron gas. Here, we develop it to the case of the hot (high-temperature) plasma, and study the collective behavior of the relativistic electrons in the hot plasma, (a) By introducing the Lienard-Weichert potential for the relativistic electrons and splitting the electron density fluctuations into the individual part and the collective part, we study the collective oscillation of the relativistic electrons resulting from the Coulomb interactions. Consequently, we derive the oscillation frequency of the hot plasma and the "Debye length" with the relativistic modification. We show that the increase of the plasma temperature, as well as that of the velocity of the electrons, leads to the decrease of the plasma frequency p and the increase of the "Debye length". Moreover, thistrend becomes more obvious when the plasma temperature is higher, (b) We study the energy loss of a fast-electron beam due to the excitation of the collective oscillation in the hot plasma. It is shown that the energy loss based on the relativistic modified collective excitation is smaller than that based on the conventional collective mode, and with the increase in the hot plasma temperature the difference becomes more obvious. In a dense electron gas, we know that for phenomena involving distances greater than the Debye length, the system behaves collectively; for distances shorter than this length, it may be treated as a collection of approximately free individual particles. For the hot plasma with the same electron density, the increase of the "Debye length" causes the decrease in the number of the electrons participating in the collective oscillation, while the increase in the number of the electrons participating in the random thermal motion. Therefore, in the hot plasma, the energy loss based on the relativistic modified collective excitation becomes smaller than that based on the conventional one.(2) Basing on the above theoretical results, we further study the interactions between the relativistic electron beams (REB) with 0.5MeV ~ 1.5MeV energies produced by ultra-short and ultra-intense lasers and the super-compressed DT core atdensities 300g/cm3 ~ 1000g/cm3 and temperatures 5keV ~ lOOkeV. The REB continuously loses energies when passing through the DT core because of experiencing two main energy-loss-mechanics such as the collective excitation and the two-body collision with relativistic modification. We show that with the increase of the plasma temperature, the energy loss caused by the collective excitation gradually decreases while that caused by the two-body collision opposes it. Then, by calculating three important physical parameters: the continuous winded range R , the maximum penetration depth l0 and the stopping time tstop, we re-examine the possibility for theREB efficiently igniting the hot spots in a DT target, and modify some theoretical results obtained by Deutsch et al. (Phys. Rev. Lett., 1996, and 2000).(3) We analyze and study the dynamic behavior for the high-temperature single bubble sonoluminescence (SBSL). (a) We introduce the characters, and the significances of SBSL, and according to its dynamic character, we briefly review the existent light-emitting mechanism, (b) Basing on the experiment... |
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