Search Results

Advanced search parameters have been applied.
open access

Measurement of subpicosecond electron bunch lengths

Description: A new frequency-resolved bunch-length measuring system has been developed at the Stanford SUNSHINE facility suitable for subpicosecond electron bunches. This method utilizes a far-infrared Michelson interferometer to measure coherent transition radiation emitted from electron bunches through optical auto-correlation. A simple and systematic way has also been developed to include interference effects caused by the beam splitter, so the electron bunch length can be easily obtained from the measur… more
Date: November 1, 1995
Creator: Lihn, Hung-chi; Bocek, D.; Kung, P.; Settakorn, C. & Wiedemann, H.
Partner: UNT Libraries Government Documents Department
open access

Measurement of subpicosecond electron pulse length

Description: A new frequency-resolved bunch-length measuring system has been developed at the Stanford SUNSHINE facility to characterize subpicosecond electron pulses. Using a far-infrared Michelson interferometer, this method measures the spectrum of coherent transition radiation emitted from electron bunches through optical autocorrelation. The electron bunch length is obtained from the measurement with a simple and systematic analysis which includes interference effects caused by the beam splitter. This … more
Date: April 1, 1996
Creator: Lihn, Hung chi
Partner: UNT Libraries Government Documents Department
open access

Model-based signal processing for laser ultrasonic signal enhancement

Description: The use of laser-based electronics in the testing of materials and structures offers various advantages over more traditional ultrasonic methods, but is often less sensitive when applied to real materials. Although high energy laser pulses can generate large ultrasonic displacements, nondestructive evaluation requires that the ablation regime be avoided, thus limiting the amount of optical energy which may be used. For this reason, signal processing of laser generated ultrasonic waveforms detec… more
Date: July 1, 1996
Creator: Huber, R. D.; Chinn, D. J.; Thomas, G. H.; Candy, J. V. & Spicer, J. B.
Partner: UNT Libraries Government Documents Department
open access

Improved operation of the Michelson interferometer ECE diagnostic on DIII-D

Description: The measurement of accurate temperature profiles is critical for transport analysis and equilibrium reconstruction in the DIII-D tokamak. Recent refinements in the Michelson interferometer diagnostic have produced more precise electron temperature measurements from electron cyclotron emission and made them available for a wider range of discharge conditions. Replacement of a lens-relay with a low-loss corrugated waveguide transmission system resulted in an increase in throughput of 6 dB and red… more
Date: May 1, 1996
Creator: Austin, M. E.; Ellis, R. F.; Doane, J. L. & James, R. A.
Partner: UNT Libraries Government Documents Department
open access

Fiber optic calorimetry

Description: A twin-bridge calorimeter using optical fiber as the sensor element was constructed and tested. This system demonstrates the principle and capability of using optical fibers for heat-flow measurements of special nuclear material. This calorimeter uses piezoelectric-generated phase-carrier modulation with subsequent electronic signal processing to allow phase shifts as small as 1 {micro}rad to be measured. The sensing element consists of 21-m lengths of single-mode optical fiber wrapped around s… more
Date: December 31, 1998
Creator: Rudy, C. R.; Bayliss, S. C.; Bracken, D. S.; Bush, I. J. & Davis, P. G.
Partner: UNT Libraries Government Documents Department
open access

Measurement of sub-picosecond bunch profiles using coherent transition radiation

Description: A technique for measuring the longitudinal profile of sub-picosecond electron bunches based on autocorrelation of coherent transition radiation is reviewed. The technique uses sub-millimeter/far-infrared Michelson interferometry to obtain the autocorrelation of transition radiation emitted from a thin conducting foil placed in the beam path. The theory of coherent radiation from a charged particle beam passing through a thin conducting foil is presented for normal and oblique incidence. Michels… more
Date: May 1, 1996
Creator: Barry, W.
Partner: UNT Libraries Government Documents Department
open access

Imaging White Light VISAR

Description: An imaging white light velocimeter consisting of two imagine superimposing Michelson interferometers in series with the target interposed is demonstrated. Interferometrically measured 2-D velocity maps can be made of moving surfaces using unlimited bandwidth incoherent and extended area sources. Short pulse and broadband chirped pulse lasers can be used to provide temporal resolution not possible with monochromatic illumination. A 20 m/s per fringe imaging velociemter is demonstrated using an o… more
Date: October 1, 1996
Creator: Erskine, D. J. & Holmes, N. C.
Partner: UNT Libraries Government Documents Department
open access

An Imaging White Light Velocimeter

Description: An imaging white light velocimeter consisting of 2 image superimposing Michelson interferometers in series with the target interposed is demonstrated. Interferometrically measured 2-D velocity maps can be made of moving surfaces using unlimited bandwith incoherent and extended source-area lamps. Short pulse and broadband chirped pulse lasers can be used to provide temporal resolution not previouslypossible with monochromatic illumination. A 20 m/x per fringe imaging velocimeter is demonstrated … more
Date: October 1, 1996
Creator: Erskine, D. J. & Holmes, N. C.
Partner: UNT Libraries Government Documents Department
open access

Observation of coherent undulator radiation from sub-picosecond electron pulses

Description: The generation and observation of high power, coherent, far-infrared undulator radiation from sub-picosecond electron bunches at the SUNSHINE facility is reported. Coherent undulator radiation tunable from 50 to 200 microns wavelength is demonstrated. Measurements of the energy (up to 1.7 mJ per 1 microsecs macropulse), frequency spectrum, and spatial distribution of the radiation are reported. Apparent exponential growth of the radiated energy as a function of undulator length is observed.
Date: September 1, 1995
Creator: Bocek, D.; Hernandez, M.; Kung, P.; Lihn, Hung-chi; Settakorn, C. & Wiedemann, H.
Partner: UNT Libraries Government Documents Department
open access

Electron Power Deposition Measurements During Ion Cyclotron Range of Frequency Heating on C-Mod

Description: A 19-channel electron cyclotron emission (ECE) grating polychromator has been added to the existing ECE diagnostics on C-Mod, which include a 9-channel polychromator, heterodyne radiometer and Michelson interferometer. The new instrument can significantly improve the radial resolution of electron power deposition measurements in ICRF experiments on C-Mod. The improved resolution is important for resolving electron power deposition in off-axis mode conversion heating regimes where the mode conve… more
Date: May 1, 1999
Creator: LeBlanc, B.; Phillips, C. K.; Schilling, G.; Taylor, G.; Wilson, J. R. & al, et
Partner: UNT Libraries Government Documents Department
open access

Material characterization using a hyperspectral infrared imaging spectrometer

Description: Fourier transform spectroscopy has found application in many areas including chemometrics, biomedical and biochemical studies, and atmospheric chemistry. This paper describes an investigation into the application of the LLNL Hyperspectral Infrared Imaging Spectrometer (HIRIS) to the non-destructive evaluation of man-made and natural materials. We begin by describing the HIRIS system and the objects studied in the investigation. Next, we describe the technique used to collect the hyperspec- tral… more
Date: October 30, 1998
Creator: Aimonetti, W D; Bixler, J V & Roberts, R S
Partner: UNT Libraries Government Documents Department
open access

Performance of a Rapid-Scan Vacuum Michelson Interferometer at the NSLS

Description: A commercial Nicolet Magna series rapid-scan Michelson Fourier Transform Infrared (FTIR) was installed in a vacuum housing and integrated into the U4IR beamline at the National Synchrotron Light Source at Brookhaven National Laboratory. The frequency reference laser was mounted outside vacuum, but the moving mirror mechanism and the dynamic alignment system for the fixed mirror were in vacuum. The performance of the instrument was measured in the usual way by measuring the repeatability of data… more
Date: September 1, 2001
Creator: Brierly, P.; Dumas, P.; Smith, M. & Williams, G. P.
Partner: UNT Libraries Government Documents Department
open access

Laser Micromachining and Information Discovery Using a Dual Beam Interferometry

Description: Lasers have proven to be among the most promising tools for micromachining because they can process features down to the size of the laser wavelength (smaller than 1 micrometer) and they provide a non-contact technology for machining. The demand for incorporating in-situ diagnostics technology into the micromachining environment is driven by the increasing need for producing micro-parts of high quality and accuracy. Laser interferometry can be used as an on-line monitoring tool and it is the ai… more
Date: December 31, 2001
Creator: Theppakuttaikomaraswamy, Senthil P.
Partner: UNT Libraries Government Documents Department
open access

Novel interferometer spectrometer for sensitive stellar radial velocimetry

Description: We describe a new kind of stellar radial velocimeter based on the series combination of a wide angle Michelson interferometer and a disperser, and which we call a fringing spectrometer. The simplest instrument response of the interferometer produces smaller instrumental noise, and the low resolution requirements of the disperser allows high efficiency and creates an etendue capability which is two orders of magnitude larger than current radial velocimeters. The instrument is compact, inexpensiv… more
Date: May 20, 1999
Creator: Erskine, D & Ge, J
Partner: UNT Libraries Government Documents Department
open access

Coherent transition radiation from a laser wakefield accelerator as an electron bunch diagnostic

Description: The observation and modeling of coherent transition radiation from femtosecond laser accelerated electron bunches is discussed. The coherent transition radiation, scaling quadratically with bunch charge, is generated as the electrons transit the plasma-vacuum boundary. Due to the limited transverse radius of the plasma boundary, diffraction effects will strongly modify the angular distribution and the total energy radiated is reduced compared to an infinite transverse boundary. The multi-nC ele… more
Date: October 22, 2004
Creator: van Tilborg, J.; Geddes, C. G. R.; Toth, C.; Esarey, E.; Schroeder, C. B.; Martin, M. C. et al.
Partner: UNT Libraries Government Documents Department
open access

Terahertz Light Source and User Area at FACET

Description: FACET at SLAC provides high charge, high peak current, low emittance electron beam that is bunched at THz wavelength scale during its normal operation. A THz light source based coherent transition radiation (CTR) from this beam would potentially be the brightest short-pulse THz source ever constructed. Efforts have been put into building this photon source together with a user area, to provide a platform to utilize this unique THz radiation for novel nonlinear and ultrafast phenomena researches… more
Date: November 8, 2011
Creator: Wu, Z.; Li, S. Z.; Litos, M.; Fisher, A. D. & Hogan, M. J.
Partner: UNT Libraries Government Documents Department
open access

Sub-picosecond streak camera measurements at LLNL: From IR to x-rays

Description: An ultra fast, sub-picosecond resolution streak camera has been recently developed at the LLNL. The camera is a versatile instrument with a wide operating wavelength range. The temporal resolution of up to 300 fs can be achieved, with routine operation at 500 fs. The streak camera has been operated in a wide wavelength range from IR to x-rays up to 2 keV. In this paper we briefly review the main design features that result in the unique properties of the streak camera and present its several sc… more
Date: December 21, 2003
Creator: Kuba, J; Shepherd, R; Booth, R; Steward, R; Lee, E W; Cross, R R et al.
Partner: UNT Libraries Government Documents Department
open access

Generation of Femtosecond Electron Pulses

Description: At the Fast Neutron Research Facility (FNRF), Chiang Mai University (Thailand), the SURIYA project has been established aiming to produce femtosecond electron pulses utilizing a combination of an S-band thermionic rf gun and a magnetic bunch compressor ({alpha}-magnet). A specially designed rf-gun has been constructed to obtain optimum beam characteristics for the best bunch compression. Simulation results show that bunch lengths as short as about 50 fs rms can be expected at the experimental s… more
Date: May 9, 2005
Creator: Jinamoon, V.; Kusoljariyakul, K.; Rimjaem, S.; Saisut, J.; Thongbai, C.; Vilaithong, T. et al.
Partner: UNT Libraries Government Documents Department
open access

Bunch Length Measurements using Coherent Radiation

Description: The accelerating field that can be obtained in a beam-driven plasma wakefield accelerator depends on the current of the electron beam that excites the wake. In the E-167 experiment, a peak current above 10 kA will be delivered at a particle energy of 28 GeV. The bunch has a length of a few ten micrometers and several methods are used to measure its longitudinal profile. Among these, autocorrelation of coherent transition radiation (CTR) is employed. The beam passes a thin metallic foil, where i… more
Date: June 24, 2005
Creator: Ischebeck, Rasmus; Barnes, Christopher; Blumenfeld, Ian; Decker, Franz-Josef; Hogan, Mark; Iverson, Richard H. et al.
Partner: UNT Libraries Government Documents Department
open access

Noise Studies of Externally Dispersed Interferometry for Doppler Velocimetry

Description: Externally Dispersed Interferometry (EDI) is the series combination of a fixed-delay field-widened Michelson interferometer with a dispersive spectrograph. This combination boosts the spectrograph performance for both Doppler velocimetry and high resolution spectroscopy. The interferometer creates a periodic comb that multiplies against the input spectrum to create moire fringes, which are recorded in combination with the regular spectrum. Both regular and high-frequency spectral components can… more
Date: May 4, 2006
Creator: Erskine, D. J.; Edelstein, J.; Lloyd, J. & Muirhead, P.
Partner: UNT Libraries Government Documents Department
open access

Material Effects and Detector Response Corrections for Bunch Length Measurements

Description: A typical diagnostic used to determine the bunch length of ultra-short electron bunches is the auto-correlation of coherent transition radiation. This technique can produce artificially short bunch length results due to the attenuation of low frequency radiation if corrections for the material properties of the Michelson interferometer and detector response are not made. Measurements were taken using FTIR spectroscopy to determine the absorption spectrum of various materials and the response of… more
Date: June 28, 2007
Creator: Zacherl, W.; Blumenfeld, I.; Berry, M.; Decker, F. -J.; Hogan, M. J.; Ischebeck, R. et al.
Partner: UNT Libraries Government Documents Department
open access

Externally Dispersed Interferometry for Precision Radial Velocimetry

Description: Externally Dispersed Interferometry (EDI) is the series combination of a fixed-delay field-widened Michelson interferometer with a dispersive spectrograph. This combination boosts the spectrograph performance for both Doppler velocimetry and high resolution spectroscopy. The interferometer creates a periodic spectral comb that multiplies against the input spectrum to create moire fringes, which are recorded in combination with the regular spectrum. The moire pattern shifts in phase in response … more
Date: March 27, 2007
Creator: Erskine, D. J.; Muterspaugh, M. W.; Edelstein, J.; Lloyd, J.; Herter, T.; Feuerstein, W. M. et al.
Partner: UNT Libraries Government Documents Department
open access

An Autocorrelation Technique for Measuring Sub-Picosecond Bunch Length Using Coherent Transition Radiation

Description: A new technique for determining sub-picosecond bunch length using infrared transition radiation and interferometry is proposed. The technique makes use of an infrared Michelson interferometer for measuring the autocorrelation of transition radiation emitted from a thin conducting foil placed in the beam path. The theory of coherent radiation from a charged particle beam passing through a thin conducting foil is presented. Subsequently, the analysis of this radiation through Michelson interferom… more
Date: April 1, 1991
Creator: Barry, Walter
Partner: UNT Libraries Government Documents Department
open access

Broadband measurements of electron cyclotron emission in TFTR (Tokamak Fusion Test Reactor) using a quasi-optical light collection system and a polarizing Michelson interferometer

Description: For the past three years, a Fourier transform spectrometer diagnostic system, employing a fast-scanning polarizing Michelson interferometer, has been operating on the TFTR tokamak at Princeton Plasma Physics Laboratory. It is used to measure the electron cyclotron emission spectrum over the range 2.5 to 18 cm/sup /minus/1/ (75-540 GHz) with a resolution of 0.123 cm/sup /minus/1/(3.7 GHz), at a rate of 72 spectra per second. The quasi-optical system for collecting the light and transporting it t… more
Date: April 1, 1988
Creator: Stauffer, F. J.; Boyd, D. A.; Cutler, R. C.; Diesso, M.; McCarthy, M. P.; Montague, J. et al.
Partner: UNT Libraries Government Documents Department
Back to Top of Screen