We demonstrate a new high-order harmonic generation mechanism reaching the "water window" spectral region in experiments with multiterawatt femtosecond lasers irradiating gas jets. A few hundred ...harmonic orders are resolved, giving μJ/sr pulses. Harmonics are collectively emitted by an oscillating electron spike formed at the joint of the boundaries of a cavity and bow wave created by a relativistically self-focusing laser in underdense plasma. The spike sharpness and stability are explained by catastrophe theory. The mechanism is corroborated by particle-in-cell simulations.
Non-destructive detection and assay of nuclear materials is one of the most critical issues for both the management of nuclear waste and the non-proliferation of nuclear materials. We use laser ...Compton scattered (LCS)
γ
-ray beams and the nuclear resonance fluorescence (NRF) for the non-destructive detection of radioactive materials. Quasi-monochromatic and energy-tunable LCS
γ
-ray beams help improve the signal-to-noise ratio during NRF measurements. We developed the conceptual design of a high-flux
γ
-ray source with an energy-recovery linac, which produces a
γ
-ray beam at the flux of
10
13
photons
/
s
.
In this paper, we discuss the execution of simulation studies using a Monte Carlo code, results of a proof-of-principle experiment for isotope detection, and the status of the development of LCS X-ray and
γ
-ray facilities.
Generation of energy-tunable gamma-rays via Laser Compton Scattering is of great interest for scientific studies and applications of “MeV” photons which interact with nuclei. One of the promising ...applications of such energy-tunable gamma-rays is the nondestructive detection and assay of nuclides which are necessary for nuclear security and safeguards. We are developing technologies relevant to gamma-ray nondestructive detection and assay, which include a high-brightness gamma-ray source based on modern laser and accelerator technologies, and gamma-ray measurement methods optimized for highly radioactive samples.
The JLab high power ERL light source Neil, G.R.; Behre, C.; Benson, S.V. ...
Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment,
02/2006, Volume:
557, Issue:
1
Journal Article
Peer reviewed
Open access
A new THz/IR/UV photon source at Jefferson Lab is the first of a new generation of light sources based on an Energy-Recovered, (superconducting) Linac (ERL). The machine has a 160
MeV electron beam ...and an average current of 10
mA in 75
MHz repetition rate hundred femtosecond bunches.
These electron bunches pass through a magnetic chicane and therefore emit synchrotron radiation. For wavelengths longer than the electron bunch the electrons radiate coherently a broadband THz ∼ half cycle pulse whose average brightness is >5 orders of magnitude higher than synchrotron IR sources. Previous measurements showed 20
W of average power extracted Carr, et al., Nature 420 (2002) 153. The new facility offers simultaneous synchrotron light from the visible through the FIR along with broadband THz production of 100
fs pulses with >200
W of average power.
The FELs also provide record-breaking laser power Neil, et al., Phys. Rev. Lett. 84 (2000) 662: up to 10
kW of average power in the IR from 1 to 14
μm in 400
fs pulses at up to 74.85
MHz repetition rates and soon will produce similar pulses of 300–1000
nm light at up to 3
kW of average power from the UV FEL. These ultrashort pulses are ideal for maximizing the interaction with material surfaces. The optical beams are Gaussian with nearly perfect beam quality. See
www.jlab.org/FEL for details of the operating characteristics; a wide variety of pulse train configurations are feasible from 10
ms long at high repetition rates to continuous operation.
The THz and IR system has been commissioned. The UV system is to follow in 2005. The light is transported to user laboratories for basic and applied research. Additional lasers synchronized to the FEL are also available. Past activities have included production of carbon nanotubes, studies of vibrational relaxation of interstitial hydrogen in silicon, pulsed laser deposition and ablation, nitriding of metals, and energy flow in proteins. This paper will present the status of the system and discuss some of the discoveries we have made concerning the physics performance, design optimization, and operational limitations of such a first generation high power ERL light source.
We have developed a 500-kV, 10-mA photocathode DC gun for energy recovery linac (ERL) light sources. A segmented ceramic insulator with guard rings is employed to improve robustness at high voltage ...operation, because this structure can prevent field emission electrons from directly striking the ceramic surface. We have recently succeeded in applying 500 kV on the ceramics for eight hours without any discharge. This high voltage testing was performed with a simple configuration without NEG pumps, cathode and anode electrodes to mainly study the field emission from a tube supporting the cathode electrode. The same high voltage testing with a full configuration necessary for beam generation was carried out up to 380 kV where some increase of radiation was observed. Up-to-date status of our gun development is presented in detail.
An energy-recovery linac (ERL) for a high-power free-electron laser (FEL) has been designed and constructed at Japan Atomic Energy Research Institute (JAERI). The construction of the ERL was ...completed and first energy-recovery operation and first FEL lasing have been demonstrated. We present the design overview and the performance of the JAERI-ERL. Future plans towards a 10-kW FEL are also described.
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