### Abstract

Original language | English |
---|---|

Pages (from-to) | 070701-1 |

Number of pages | 70700 |

Journal | Physical Review Special Topics: Accelerators and Beams |

Volume | 6 |

Issue number | 7 |

DOIs | |

Publication status | Published - Jul 2003 |

### Fingerprint

### Keywords

- electron beam shot noise
- free electron lasers
- lasers
- electrons
- self-amplified spontaneous emission regime
- x-rays
- algorithms
- optics

### Cite this

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**Unified model of electron beam shot noise and coherent spontaneous emission in the helical wiggler free electron laser.** / McNeil, B.W.J.; Poole, M.W.; Robb, G.R.M.

Research output: Contribution to journal › Article

TY - JOUR

T1 - Unified model of electron beam shot noise and coherent spontaneous emission in the helical wiggler free electron laser

AU - McNeil, B.W.J.

AU - Poole, M.W.

AU - Robb, G.R.M.

PY - 2003/7

Y1 - 2003/7

N2 - A numerical algorithm for simulating electron beam shot noise in free electron lasers (FELs) is presented. Shot noise is a source of spontaneous emission that may be amplified in the self-amplified spontaneous emission regime of operation. This regime is of great importance to XUV and x-ray FELs where the spontaneous emission is currently the only effective source available for amplification. The algorithm uses a quasiuniform phase-space distribution of appropriately charge weighted macroparticles. The statistical properties of the macroparticles are derived directly from the temporal Poisson statistical properties of the real electron distribution. Unlike previous algorithms, ours does not rely upon any averaging over a resonant radiation period time scale and so more correctly describes the underlying physics. The algorithm also allows shot noise to be modeled self-consistently in unaveraged FEL models which are able to describe subwavelength phenomena such as coherent spontaneous emission (CSE). The algorithm is used in the unaveraged 1D FEL numerical simulation code FemFel and demonstrates spontaneous emission due to shot noise and CSE in both rectangular and Gaussian electron pulse current profiles. The preliminary results show good qualitative and quantitative agreement with theory.

AB - A numerical algorithm for simulating electron beam shot noise in free electron lasers (FELs) is presented. Shot noise is a source of spontaneous emission that may be amplified in the self-amplified spontaneous emission regime of operation. This regime is of great importance to XUV and x-ray FELs where the spontaneous emission is currently the only effective source available for amplification. The algorithm uses a quasiuniform phase-space distribution of appropriately charge weighted macroparticles. The statistical properties of the macroparticles are derived directly from the temporal Poisson statistical properties of the real electron distribution. Unlike previous algorithms, ours does not rely upon any averaging over a resonant radiation period time scale and so more correctly describes the underlying physics. The algorithm also allows shot noise to be modeled self-consistently in unaveraged FEL models which are able to describe subwavelength phenomena such as coherent spontaneous emission (CSE). The algorithm is used in the unaveraged 1D FEL numerical simulation code FemFel and demonstrates spontaneous emission due to shot noise and CSE in both rectangular and Gaussian electron pulse current profiles. The preliminary results show good qualitative and quantitative agreement with theory.

KW - electron beam shot noise

KW - free electron lasers

KW - lasers

KW - electrons

KW - self-amplified spontaneous emission regime

KW - x-rays

KW - algorithms

KW - optics

UR - http://dx.doi.org/10.1103/PhysRevSTAB.6.070701

U2 - 10.1103/PhysRevSTAB.6.070701

DO - 10.1103/PhysRevSTAB.6.070701

M3 - Article

VL - 6

SP - 70701

EP - 70701

JO - Physical Review Special Topics: Accelerators and Beams

JF - Physical Review Special Topics: Accelerators and Beams

SN - 1098-4402

IS - 7

ER -