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Title: Femtosecond Electron and Photon Pulses Facility in Thailand

Abstract

Femtosecond electron and photon pulses facility has been established as SURIYA project at the Fast Neutron Research Facility (FNRF). Femtosecond electron bunches can be generated from a system consisting of an RF gun with a thermionic cathode, an alpha magnet as an magnetic bunch compressor, and a linear accelerator as a post acceleration section. Femtosecond electron pulses can be used directly or used as a source to produce equally short electromagnetic (EM) radiation pulses via certain kind of radiation production processes. At SURIYA project, we are interested especially in production of radiation in Far-infrared (FIR) regime. At these wavelengths, the radiation from femtosecond electron pulses is emitted coherently resulting in high intensity radiation. Overview of the facility, the generation of femtosecond electron bunches, the theoretical background of coherent transition radiation and the recent experimental results will be presented and discussed in this paper.

Authors:
; ; ; ; ; ;  [1]; ;  [2]
  1. Fast Neutron Research Facility (FNRF), Physics Department, Chiang Mai University, Chiang Mai 50200 (Thailand)
  2. Institute for Science Technology Research and Development, Chiang Mai University, Chiang Mai 50200 (Thailand)
Publication Date:
OSTI Identifier:
21043425
Resource Type:
Journal Article
Resource Relation:
Journal Name: AIP Conference Proceedings; Journal Volume: 879; Journal Issue: 1; Conference: 9. international conference on synchrotron radiation instrumentation, Daegu (Korea, Republic of), 28 May - 2 Jun 2006; Other Information: DOI: 10.1063/1.2436052; (c) 2007 American Institute of Physics; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
43 PARTICLE ACCELERATORS; ACCELERATION; BEAM BUNCHING; CATHODES; ELECTRON BEAMS; ELECTRONS; FAST NEUTRONS; LINEAR ACCELERATORS; MAGNETS; PHOTON EMISSION; PHOTONS; PULSES; THAILAND; TRANSITION RADIATION; WAVELENGTHS

Citation Formats

Rimjaem, S., Thongbai, C., Jinamoon, V., Kangrang, N., Kusoljariyakul, K., Saisut, J., Vilaithong, T., Rhodes, M. W., and Wichaisirimongkol, P. Femtosecond Electron and Photon Pulses Facility in Thailand. United States: N. p., 2007. Web. doi:10.1063/1.2436052.
Rimjaem, S., Thongbai, C., Jinamoon, V., Kangrang, N., Kusoljariyakul, K., Saisut, J., Vilaithong, T., Rhodes, M. W., & Wichaisirimongkol, P. Femtosecond Electron and Photon Pulses Facility in Thailand. United States. doi:10.1063/1.2436052.
Rimjaem, S., Thongbai, C., Jinamoon, V., Kangrang, N., Kusoljariyakul, K., Saisut, J., Vilaithong, T., Rhodes, M. W., and Wichaisirimongkol, P. Fri . "Femtosecond Electron and Photon Pulses Facility in Thailand". United States. doi:10.1063/1.2436052.
@article{osti_21043425,
title = {Femtosecond Electron and Photon Pulses Facility in Thailand},
author = {Rimjaem, S. and Thongbai, C. and Jinamoon, V. and Kangrang, N. and Kusoljariyakul, K. and Saisut, J. and Vilaithong, T. and Rhodes, M. W. and Wichaisirimongkol, P.},
abstractNote = {Femtosecond electron and photon pulses facility has been established as SURIYA project at the Fast Neutron Research Facility (FNRF). Femtosecond electron bunches can be generated from a system consisting of an RF gun with a thermionic cathode, an alpha magnet as an magnetic bunch compressor, and a linear accelerator as a post acceleration section. Femtosecond electron pulses can be used directly or used as a source to produce equally short electromagnetic (EM) radiation pulses via certain kind of radiation production processes. At SURIYA project, we are interested especially in production of radiation in Far-infrared (FIR) regime. At these wavelengths, the radiation from femtosecond electron pulses is emitted coherently resulting in high intensity radiation. Overview of the facility, the generation of femtosecond electron bunches, the theoretical background of coherent transition radiation and the recent experimental results will be presented and discussed in this paper.},
doi = {10.1063/1.2436052},
journal = {AIP Conference Proceedings},
number = 1,
volume = 879,
place = {United States},
year = {Fri Jan 19 00:00:00 EST 2007},
month = {Fri Jan 19 00:00:00 EST 2007}
}
  • Abstract is not available
  • We report the results of experimental and theoretical investigations of the two-color, two-photon ionization of Ar atoms, using femtosecond pulses of infrared laser radiation in combination with its extreme-ultraviolet harmonics. It is shown that the intensities of the photoelectron lines resulting from the absorption of photons from both fields strongly depend both on the respective phases of the fields and on atomic quantities such as the asymmetry parameter. These phases, which are notoriously difficult to measure, can be estimated by changing the polarization state of the laser radiation.
  • We extend the powerful frequency-domain analysis of femtosecond two-photon absorption to the intermediate-field regime of considerable absorption yields, where additionally to the weak-field nonresonant two-photon transitions also four-photon transitions play a role. Consequently, we rationally find that the absorption is enhanced over the transform-limited pulse by any shaped pulse having a spectral phase that is antisymmetric around one-half of the transition frequency and a spectrum that is asymmetric around it (red or blue detuned according to the system). The enhancement increases as the field strength increases. The theoretical results for Na are verified experimentally.
  • Two-photon double ionization (TPDI) of D{sub 2} is studied for 38-eV photons at the Free Electron Laser in Hamburg (FLASH). Based on model calculations, instantaneous and sequential absorption pathways are identified as separated peaks in the measured D{sup +}+D{sup +} fragment kinetic energy release (KER) spectra. The instantaneous process appears at high KER, corresponding to ionization at the molecule's equilibrium distance, in contrast to sequential ionization mainly leading to low-KER contributions. Measured fragment angular distributions are in good agreement with theory.
  • We study in detail the coherent interference mechanism leading to the intermediate-field two-photon absorption enhancement recently found for shaped femtosecond pulses with spectral phases that are antisymmetric around one-half of the transition frequency. We particularly investigate the tolerance of the phenomenon to the phase deviation from perfect antisymmetry. We theoretically and experimentally find that this tolerance increases as the field strength increases. For the present Na excitation, the enhancement occurs even when {approx}30% of the phase pattern is not antisymmetric. Our findings are of particular importance for multichannel coherent control scenarios.