Design, Modeling, and Control of Laser Beam Optics, 1992
The optical cavity of the Boeing visible free electron laser was reconfigured from a concentric c... more The optical cavity of the Boeing visible free electron laser was reconfigured from a concentric cavity to a glancing incidence ring resonator in late 1989 and was operated until December 1990. the crucial requirement for the optical cavity of an FEL is to provide an optical mode which is spatially and temporally matched to the electron beam as it moves through the wiggler. Several new optical diagnostics were developed to determine when the above requirement was satisfied. This paper will discuss those diagnostics which achieved and maintained the alignment of the ring resonator within tolerance to lase and measured the quality of lasing. The new diagnostics included measurements of the focus position and Rayleigh range of the ring resonator optics to determine the spatial match of the optical mode through the wiggler, and a measurement of the position of the optical axis for multiple passes around the ring resonator to determine the stability of the resonator alignment. Accelerator performance was determined by measuring the electron beam pulse width and charge, which indicated electron beam brightness, and by measuring the width of the spontaneous emission spectrum, which gave an indication of the alignment between the electron beam and the optical axis. Temporal overlap of electron and optical pulses was assured by measuring the optical cavity length. In addition, several other diagnostics which indicated FEL performance will be described: optical energy per micropulse, small signal gain, ringdown loss, laser pulse width, laser wavelength, and time resolved spectroscopy.
Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment, 1997
This paper describes pulse compression and energy recovery experiments using an RF photocathode g... more This paper describes pulse compression and energy recovery experiments using an RF photocathode gun and injector accelerator at a fundamental RF of 433 MHz (1f) and a third-harmonic RF accelerator section operating at 1300 MHz (3f). For pulse compression, the 3f section is used both to program the energy slew and correct for RF-induced curvature in the electron beam micropulse
The π mode or accelerating mode in a 1.6 cell rf gun is normally the only mode considered in rf g... more The π mode or accelerating mode in a 1.6 cell rf gun is normally the only mode considered in rf gun simulations. However, due to the finite Q there is a small but measurable 0 mode present even at steady state. The π mode by definition has a 180° phase shift between cells but this phase shift for the total field is several degrees different. This results in a correlated energy spread exiting the gun. A comparison of simulation and experiment will be shown.
... QE X: 4.438 Y: 7.016e-006 X: 4.299 Y: 5.053e-006 4 Comparison of Expt. and Theory for the Int... more ... QE X: 4.438 Y: 7.016e-006 X: 4.299 Y: 5.053e-006 4 Comparison of Expt. and Theory for the Intrinsic Emittance CP Hauri et al., PRL 104,234802(2010) QE of Copper vs. Effective Work Function 2 3mc eff x n ϕ ω ... lN Q 2 2 0 16 π ρ = = Leap of faith: Assume 4 2 2 r x p p ≈ mc p x ...
We have measured the angular asymmetry in the (γ, n) reaction on natural lead, cadmium, and calci... more We have measured the angular asymmetry in the (γ, n) reaction on natural lead, cadmium, and calcium in the energy region of the isovector quadrupole resonance (20–40 MeV). The asymmetry increases from low values, about 0.2, to high values, 0.6–0.8, where this resonance is expected. This increasing asymmetry is interpreted as resulting from the interference between the E1 and E2 isovector amplitudes. We have fitted direct−semidirect calculations for lead and cadmium and have obtained resonance energies of 23.5 ± 1.5 and 26.5 ± 1.5 MeV for these elements, respectively. For calcium, preliminary results indicate a resonance energy of 34 ± 2 MeV. The widths are found to be considerably larger than those of the E1 resonance.
Design, Modeling, and Control of Laser Beam Optics, 1992
The optical cavity of the Boeing visible free electron laser was reconfigured from a concentric c... more The optical cavity of the Boeing visible free electron laser was reconfigured from a concentric cavity to a glancing incidence ring resonator in late 1989 and was operated until December 1990. the crucial requirement for the optical cavity of an FEL is to provide an optical mode which is spatially and temporally matched to the electron beam as it moves through the wiggler. Several new optical diagnostics were developed to determine when the above requirement was satisfied. This paper will discuss those diagnostics which achieved and maintained the alignment of the ring resonator within tolerance to lase and measured the quality of lasing. The new diagnostics included measurements of the focus position and Rayleigh range of the ring resonator optics to determine the spatial match of the optical mode through the wiggler, and a measurement of the position of the optical axis for multiple passes around the ring resonator to determine the stability of the resonator alignment. Accelerator performance was determined by measuring the electron beam pulse width and charge, which indicated electron beam brightness, and by measuring the width of the spontaneous emission spectrum, which gave an indication of the alignment between the electron beam and the optical axis. Temporal overlap of electron and optical pulses was assured by measuring the optical cavity length. In addition, several other diagnostics which indicated FEL performance will be described: optical energy per micropulse, small signal gain, ringdown loss, laser pulse width, laser wavelength, and time resolved spectroscopy.
Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment, 1997
This paper describes pulse compression and energy recovery experiments using an RF photocathode g... more This paper describes pulse compression and energy recovery experiments using an RF photocathode gun and injector accelerator at a fundamental RF of 433 MHz (1f) and a third-harmonic RF accelerator section operating at 1300 MHz (3f). For pulse compression, the 3f section is used both to program the energy slew and correct for RF-induced curvature in the electron beam micropulse
The π mode or accelerating mode in a 1.6 cell rf gun is normally the only mode considered in rf g... more The π mode or accelerating mode in a 1.6 cell rf gun is normally the only mode considered in rf gun simulations. However, due to the finite Q there is a small but measurable 0 mode present even at steady state. The π mode by definition has a 180° phase shift between cells but this phase shift for the total field is several degrees different. This results in a correlated energy spread exiting the gun. A comparison of simulation and experiment will be shown.
... QE X: 4.438 Y: 7.016e-006 X: 4.299 Y: 5.053e-006 4 Comparison of Expt. and Theory for the Int... more ... QE X: 4.438 Y: 7.016e-006 X: 4.299 Y: 5.053e-006 4 Comparison of Expt. and Theory for the Intrinsic Emittance CP Hauri et al., PRL 104,234802(2010) QE of Copper vs. Effective Work Function 2 3mc eff x n ϕ ω ... lN Q 2 2 0 16 π ρ = = Leap of faith: Assume 4 2 2 r x p p ≈ mc p x ...
We have measured the angular asymmetry in the (γ, n) reaction on natural lead, cadmium, and calci... more We have measured the angular asymmetry in the (γ, n) reaction on natural lead, cadmium, and calcium in the energy region of the isovector quadrupole resonance (20–40 MeV). The asymmetry increases from low values, about 0.2, to high values, 0.6–0.8, where this resonance is expected. This increasing asymmetry is interpreted as resulting from the interference between the E1 and E2 isovector amplitudes. We have fitted direct−semidirect calculations for lead and cadmium and have obtained resonance energies of 23.5 ± 1.5 and 26.5 ± 1.5 MeV for these elements, respectively. For calcium, preliminary results indicate a resonance energy of 34 ± 2 MeV. The widths are found to be considerably larger than those of the E1 resonance.
Uploads
Papers