Biomedical subjects
Publications and source records attributed to Baifei Shen.
An approach for producing a large quantity of neutrons is proposed. It involves compression of a fuel foil and confinement of the resulting plasma between two intense laser pulses. It is shown that two circularly polarized laser pulses of amplitude a = 7 illuminating a deuterium-tritium foil of areal density 3.3 x 10(18) cm(-2) can produce about 4.2 x 10(6) neutrons per joule of the input laser energy.
Ultrashort high-intensity electromagnetic solitons in both underdense and overdense plasmas are investigated. Comparison is made for solitons with smooth and sharp electron density profiles. It is found that subcycle relativistic solitons can propagate from low-density to high-density plasmas.
Ponderomotive force driven acceleration of an electron at the focus of a high-intensity short-pulse laser is considered. Accounting for the asymmetry of acceleration and deceleration due to the evolution of the Gaussian laser beam waist, the energized electron is extracted from the laser pulse by the longitudinal ponderomotive force. It is shown that an electron's energy gain in the range of MeV can be realized for laser intensities above 10(19) W microm(2)/cm(2). Final energy gain as a function of the scattering angle and the electron's initial position has also been discussed.
Channeling in overdense plasma by relativistic laser pulse is investigated. The critical laser power needed to maintain a plasma channel as well as the mode profiles of the electromagnetic fields in the channel cross section are obtained analytically. A scaling law showing that the critical power is proportional to the square of the background plasma density is found.
Interaction of two oppositely directed ultraintense laser pulses with two closely placed thin foils is modeled analytically and investigated by particle-in-cell simulation. It is shown that laser energy can be trapped and accumulated between the foils. The intensity could reach a 100-fold that of the pump lasers. The trapping is found to be bistable and the parameters for stable energy confinement and enhancement are given. The ultrahigh fields that can be produced have many potential applications, including that of verifying nonlinear quantum electrodynamics effects.
Electron-positron and gamma-photon production by high-intensity laser pulses is investigated for a special target geometry, in which two pulses irradiate a very thin foil (10-100 nm < skin depth) with same intensity from opposite sides. A stationary solution is derived describing foil compression between the two pulses. Circular polarization is chosen such that all electrons and positrons rotate in the plane of the foil. We discuss the laser and target parameters required in order to optimize the gamma photon and pair production rate. We find a gamma-photon intensity of 7x10(27)/sr s and a positron density of 5x10(22)/cm(3) when using two 330 fs, 7x10(21) W/cm(2) laser pulses.