tags:
view citation format
11 papers
| title: | Production of High Harmonic X-ray Radiation from Non-linear Thomson Scattering at LLNL PLEIADES |
| format: | conference procceeding |
| conference: | 2005 Particle Accelerator Conference |
| year: | 2005 |
| 11 authors: | | | | | | | | | | | |
| abstract: | We describe an experiment for production of high harmonic x-ray radiation from Thomson backscattering of an ultra-short high power density laser by a relativistic electron beam at the PLEIADES facility at LLNL. In this scenario, electrons execute a ``figure-8'' motion under the influence of the high-intensity laser field, where the constant characterizing the field strength is expected to exceed unity: $a_{L}=eE_{L}/m_{e}c\omega_{L}\geq1$. With large $a_{L}$ this motion produces high harmonic x-ray radiation and significant broadening of the spectral peaks. This paper is intended to give a layout of the PLEIADES experiment, along with progress towards experimental goals. |
| keywords: | |
| Download | View | Details | edit | delete | |
| title: | High Energy Gain of Trapped Electrons in a Tapered, Diffraction-Dominated Inverse-Free-Electron Laser |
| format: | preprint |
| year: | 2005 |
| 17 authors: | | | | | | | | | | | | | | | | | |
| abstract: | Energy gain of trapped electrons in excess of 20 MeV has been demonstrated in an Inverse-Free- Electron-Laser (IFEL) accelerator experiment. A 14.5 MeV electron beam is copropagated with a 400 GW CO2 laser beam in a 50 cm long undulator strongly tapered in period and ¯eld amplitude. The Rayleigh range of the laser, » 1.8 cm, is much shorter than the undulator length yielding a di®raction-dominated interaction. Experimental results on the dependence of the acceleration on injection energy, laser focus position, and laser power are discussed. Simulations, in good agreement with the experimental data, show that most of the energy gain occurs in the ¯rst half of the undulator at a gradient of 70 MeV/m and that the structure in the measured energy spectrum arises because of higher harmonic IFEL interaction in the second half of the undulator. |
| keywords: | |
| Download | View | Details | edit | delete | |
| title: | Pulsed-laser nonlinear Thomson scattering for general scattering geometries |
| format: | journal article |
| year: | 2005 |
| 3 authors: | | | |
| abstract: | In a recent paper it has been shown that single electron Thomson backscatter calculations can be performed including the effects of pulsed high intensity lasers. In this paper we present a more detailed treatment of the problem and present results for more general scattering geometries. In particular, we present new results for 90 |
| keywords: | |
| Download | View | Details | edit | delete | |
| title: | Photon beam diagnostics for VISA FEL |
| format: | conference procceeding |
| conference: | 1999 Particle Accelerator Conference |
| year: | 1999 |
| 17 authors: | | | | | | | | | | | | | | | | | |
| abstract: | The VISA (Visible to Infrared SASE Amplifier) project is designed to be a SASE-FEL driven to saturation in the sub-micron wavelength region. Its goal is to test various aspects of the existing theory of self-amplified spontaneous emission, as well as numerical codes. Measurements include: angular and spectral distribution of the FEL light at the exit and inside of the undulator; electron beam micro-bunching using CTR; single-shot time resolved measurements of the pulse profile, using an auto-correlation technique and FROG algorithm. The diagnostics are designed to provide maximum information on the physics of the SASE-FEL process, to ensure a close comparison of the experimental results with theory and simulations. (9 References). |
| keywords: | |
| Download | View | Details | edit | delete | |
| title: | Very High Energy Gain at the Neptune Inverse Free Electron Laser Experiment |
| format: | journal article |
| year: | Dec 2004 |
| 16 authors: | | | | | | | | | | | | | | | | |
| abstract: | We report the observation of energy gain in excess of 20 MeV at the Inverse Free Electron Laser Accelerator experiment at the Neptune Laboratory at UCLA. A 14.5 MeV electron beam is injected in an undulator strongly tapered in period and field amplitude. The IFEL driver is a CO2 10.6 µm laser with power larger than 400 GW. The Rayleigh range of the laser, ~ 1.8 cm, is much shorter than the undulator length so that the interaction is diffraction dominated. A few per cent of the injected particles are trapped in a stable accelerating bucket. Electrons with energies up to 35 MeV are measured by a magnetic spectrometer. Three-dimensional simulations, in good agreement with the measured electron energy spectrum, indicate that most of the acceleration occurs in the first 25 cm of the undulator, corresponding to an energy gradient larger than 70 MeV/m. The measured energy spectrum also indicates that higher harmonic Inverse Free Electron Laser interaction takes place in the second section of the undulator. |
| keywords: | pbpl |
| Download | View | Details | edit | delete | |
| title: | Investigation of X-Ray Harmonics in the Polarized Nonlinear Inverse Compton Scattering Experiment at UCLA |
| format: | conference procceeding |
| conference: | Proceedings of the 27th International Free Electron Laser Conference |
| year: | 2005 |
| 8 authors: | | | | | | | | |
| abstract: | An Inverse Compton Scattering (ICS) experiment, which will investigate nonlinear properties of scattering utilizing a terawatt CO2 laser system with various polarizations, is ongoing at the UCLA Neptune Laboratory. When the normalized amplitude of the incident laser's vector potential ao is larger than unity the scattering occurs in the nonlinear region; therefore, higher harmonics are also produced. ICS can be used, e.g., for a polarized positron source by striking a thin target (such as tungsten) with the polarized X-rays. As such, it is critical to demonstrate the production of polarized scattered photons and to investigate the ICS process as it enters the nonlinear regime. We present the description of the experimental set up and equipment utilized, including diagnostics for electron and photon beam detection. We present the current status of the experiment. electron beam focusing and recollimating systems consist of 5 equal strength and length PMQs each, set up as a modified FF-DD-F triplet. The high power CO2 laser is focused by an off-axis parabolic mirror with a 12.7 cm diameter and 17 cm focal length. Since the divergence of the scattered photons is quite large (-I/, where 28) it is necessary to place the detector (soft X-ray camera and/or micro-channel plate) very close to the IP. This requires bending the electron beam immediately after the recollimating PMQ system, in a very short bending radius. To this end, we have designed and built a permanent magnet dipole (PMD) with a -60 mm bending radius for this purpose. Table 1: Electron and Laser Beam Parameters |
| keywords: | pbpl |
| Download | View | Details | edit | delete | |
| title: | UCLA Neptune Ramped Electron Bunch Experiment |
| format: | journal article |
| year: | 2004 |
| 5 authors: | | | | | |
| abstract: | A ramped electron bunch (i.e. one having a current density which rises linearly from the head to the tail and then drops sharply to zero) has been predicted to be an ideal drive beam for the plasma wake field accelerator due to the large transformer ratio it is capable of generating. A scheme was recently proposed for the creation of a relativistic electron bunch that approximates a ramped current profile [England, et al., AIP Conf. Proc. 647, p.884 (2002)], using a dogleg or dispersionless translating section as a bunch compressor. An experiment is underway at the Neptune laboratory using this scheme to create such a beam. The diagnostic being developed for measuring the temporal profile of the beam is an X-Band transverse deflecting mode cavity. ©2004 American Institute of Physics |
| keywords: | pbpl |
| Download | View | Details | edit | delete | |
| title: | Study of X-ray Harmonics of the Polarized Inverse Compton Scattering Experiment at UCLA |
| format: | journal article |
| year: | 2004 |
| 8 authors: | | | | | | | | |
| abstract: | We propose an Inverse Compton Scattering (ICS) experiment, which will investigate nonlinear properties of the scattering utilizing the terawatt CO2 laser system with various polarizations in Neptune Laboratory at UCLA. When the normalized amplitude of the vector potential a0 is larger than unity the scattering occurs in the nonlinear region; therefore, higher harmonics are also produced. We present a calculation tool for the Double Differential Spectrum (DDS) distribution and total number of photons produced for both head-on and 90° scattering. We decided to do the experiment at 90° to avoid complications due to strong diffraction of the incoming laser. We discuss the electron and laser beam parameters for the experiment. ©2004 American Institute of Physics |
| keywords: | pbpl |
| Download | View | Details | edit | delete | |
| title: | Acceleration of electrons in a diffraction-dominated IFEL |
| format: | journal article |
| year: | 2004 |
| 16 authors: | | | | | | | | | | | | | | | | |
| abstract: | We report on the observation of energy gain in excess of 20 MeV at the Inverse Free Electron Laser Accelerator ex- periment at the Neptune Laboratory at UCLA. A 14.5 MeV electron beam is injected in a 50 cm long undulator strongly tapered both in period and field amplitude. A CO2 10.6 μm laser with power > 300 GW is used as the IFEL driver. The Rayleigh range of the laser ( ∼ 1.8 cm) is shorter than the undulator length so that the interaction is diffraction dom- inated. Few per cent of the injected particles are trapped in stable accelerating buckets and electrons with energies up to 35 MeV are detected on the magnetic spectrometer. Three dimensional simulations are in good agreement with the electron energy spectrums observed in the experiment and indicate that substantial energy exchange between laser and electron beam only occurs in the first 25-30 cm of the undulator. An energy gradient of > 70 MeV is inferred. In the second section of the undulator higher harmonic IFEL interaction is observed. |
| keywords: | pbpl |
| Download | View | Details | edit | delete | |
| title: | High Energy Gain of Trapped Electrons in a Tapered, Diffraction-Dominated Inverse-Free-Electron Laser |
| format: | journal article |
| year: | |
| 17 authors: | | | | | | | | | | | | | | | | | |
| abstract: | Energy gain of trapped electrons in excess of 20 MeV has been demonstrated in an inverse-freeelectron-laser (IFEL) accelerator experiment. A 14.5 MeVelectron beam is copropagated with a 400 GW CO2 laser beam in a 50 cm long undulator strongly tapered in period and field amplitude. The Rayleigh range of the laser, 1:8 cm, is much shorter than the undulator length yielding a diffraction-dominated interaction. Experimental results on the dependence of the acceleration on injection energy, laser focus position, and laser power are discussed. Simulations, in good agreement with the experimental data, show that most of the energy gain occurs in the first half of the undulator at a gradient of 70 MeV=m and that the structure in the measured energy spectrum arises because of higher harmonic IFEL interaction in the second half of the undulator. |
| keywords: | |
| Download | View | Details | edit | delete | |
| title: | High Energy gain IFEL at the UCLA Neptune Laboratory |
| format: | journal article |
| year: | |
| 16 authors: | | | | | | | | | | | | | | | | |
| abstract: | We report on the observation of energy gain in excess of 20MeV at the Inverse Free Electron Laser Accelerator experiment at the Neptune Laboratory at UCLA. A 14.5MeV electron beam is injected in a 50cm longundulator strongly tapered both in period and field amplitude. A CO210.6μm laser with power > 400GW is used as the IFEL driver. The Rayleigh range of the laser(∼1.8cm)is shorter than the undulator length so that the interaction is diffraction dominated. Few per cent of the injected particles are trapped instable accelerating buckets and electrons with energies up to 35 MeV are detected on the magnetic spectrometer. Three dimensional simulations are in good agreement with the electron energy spectrums observed in the experiment and indicate that substantial energy exchange between laser and electron beam only occurs in the first 25-30 cm of the undulator. Anenergygradientof>70MeVisinferred. In these cond section of the undulator higher harmonic IFEL interaction is observed. |
| keywords: | |
| Download | View | Details | edit | delete | |