Author: Samant, S.A.
Paper Title Page
WEPZ025 Study of Self-injection of an Electron Beam in a Laser-driven Plasma Cavity 2820
 
  • S. Krishnagopal, S.A. Samant, D. Sarkar
    BARC, Mumbai, India
  • P. Jha
    Lucknow University, Lucknow, India
  • A.K. Upadhyay
    CBS, Mumbai, India
 
  Over the last few years, remarkable advances in laser wakefield acceleration of electrons have been achieved, including quasi-monoenergetic beams and GeV energy in a few centimeters. However, it is necessary to achieve good beam quality (large current, low energy-spread and low emittance) for applications such as free-electron lasers. We study self-injection in two regimes of the laser-plasma interaction: the moderate intensity, self-guiding regime, and the low intensity, near-injection-threshold regime, both in a homogeneous plasma that completely fills the simulation volume. We find good beam quality with injection of on-axis electrons, especially at lower intensity. We also study the case when the laser has to travel through vacuum before entering the plasma. We find that injection here is completely different, from off-axis electrons, and the beam quality is poorer.  
 
THPC085 Effect of mirror-tilt on the mode-structure in an oscillator FEL 3092
 
  • S. Krishnagopal, S.A. Samant
    BARC, Mumbai, India
 
  In an oscillator free-electron laser (FEL) the power coupled out depends strongly on the mode configuration at the out-coupling mirror. This mode configuration is affected by many parameters such as the resonator configuration, FEL wavelength, etc. In addition, mirror alignment also plays an important role in determining the mode structure. In this paper we use three-dimensional simulations (GENESIS+OPC), to study the effect of mirror tilt on the out-coupled power. We find that mirror-tilt can severely distort the mode, and can introduce non-Gaussian, non-axisymmetric modes. In this regard the confocal configuration is more robust compared to the concentric.