Coherent Radiation from High- Current Electron Beams of a Linear Accelerator and Its Applications S. Okuda 1987-2002 ISIR, Osaka Univ. 2002- Research Institute for Advanced Science and Technology (RIAST), Osaka Prefecture Univ. Coworkers: Osaka Pref. Univ. R. Taniguchi, T. Kojima Osaka Univ. M. Nakamura, M. Takanaka, R. Kato Kyoto Univ. T. Takahashi Kangwon Univ. S. Nam
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Coherent Radiation from High-Current Electron Beams of a Linear Accelerator and Its Applications S. Okuda 1987-2002 ISIR, Osaka Univ. 2002- Research Institute.
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Coherent Radiation from High-Current
Electron Beams of a Linear Accelerator
and Its Applications
S. Okuda
1987-2002 ISIR, Osaka Univ. 2002- Research Institute for Advanced Science and Technology (RIAST), Osaka Prefecture Univ. Coworkers: Osaka Pref. Univ. R. Taniguchi, T. Kojima Osaka Univ. M. Nakamura, M. Takanaka, R. Kato Kyoto Univ. T. Takahashi Kangwon Univ. S. Nam
Features of FELs Tunability Subpicosecond short pulse High peak power (MW)
Single passage (no cavity mirror)High gainX-ray FEL
SASE (Self-amplified spontaneous emission) FEL
First lasing: 1991
Oscillation FEL
Output power of FEL light
Wavelength: 40 mOutput power: 800 J/macropulse
First lasing: 1994
FEL facility at Osaka Univ.
FEL facilities
IR-FIR user facilities
Visible-UV Storage ring FELs
High power IR FELs
Superconducting linacs
X-ray SASE projects
×N (~ 1011)
Coherent radiation from an electron bunch
Phys. Rev. Lett. 1991
Our observation of coherent radiation
High intensity in a submillimeter to millimeter range (THz – 100 GHz)Continuous spectrumCoherencePico-second short pulseSynchronization with the electron bunch
Absorption spectroscopyAnalysis of transient phenomenaImagingCoherent excitationPump and probe analysis
Characteristics of CR
Applications of CR
Applications of the radiation
Electron bunch shape monitor
Far-infrared light source
for absorption spectroscopy
Bunch form factors for various bunch shapes
Gaussian
RectangularIsosceles triangular
Wavelength is normalized by the FWHM bunch length.
Bunch sape monitoring system
Coherenttransition radiation
L-band LINAC
QQ
Bunch compressorAl foil
Al Mirror
Interferometer
Detector
Streak camera
Shielding wall
Detector
Electron beam
Cherenkov radiation
Streak measurement Time resolution 0.9 psMeasurement of the coherent transition radiation Wavelength range 0.4-2 mm Wavenumber resolution 0.2 cm-1 Interferometer: Martin-Pupplet type Detector: Liquid-He-cooled Si bolometer
Experimental setup for absorption spectroscopy using CTR
Detector
Detector
Monochromator
Splitter
Shielding wall
Sample
Plane mirror
L-band linac
Transition radiation
Al plate
Quadrupole magnets
Electron beam
Window Concave mirror
Detector
Detector
Monochromator
Splitter
Shielding wall
Sample
Plane mirror
L-band linac
Transition radiation
Al plate
Quadrupole magnets
Electron beam
Window Concave mirror
Absorption spectroscopy for water
Incident LightQuartz
Water
Incident LightQuartz
Water
Temperature: 22 ℃Thickness of the sample: 186 m
(a)
(b)
1.5
2
2.5
3
9 10 11 12 13 14 15
0
50
100
150
200
9 10 11 12 13 14 15
Wavenumber (cm -¹)
Ab
sorp
tion
Co
effi
cie
nt
Re
fra
ctiv
e In
de
x(
Np
cm
-1)
Wavenumber (cm -¹)
(a)
(b)
1.5
2
2.5
3
9 10 11 12 13 14 15
0
50
100
150
200
9 10 11 12 13 14 15
Wavenumber (cm -¹)
Ab
sorp
tion
Co
effi
cie
nt
Re
fra
ctiv
e In
de
x(
Np
cm
-1)
Wavenumber (cm -¹)
Resolution: 1%
Setup for imaging
X-Y Stage
Collimator
Sample
Sample
Collimator (Al plate)
CTR
CTR
X-Y Stage
Collimator
Sample
X-Y Stage
Collimator
Sample
Sample
Collimator (Al plate)
CTR
CTR
MonochromatorDetector
Detector
SampleBeam Splitter
X-Y Stage
Collimator
Oscilloscope X-Y Stage Controller
CTR
MonochromatorDetector
Detector
SampleBeam Splitter
X-Y Stage
Collimator
Oscilloscope X-Y Stage Controller
CTR
Dried
1 cm 1 cm
Dried
1 cm 1 cm
Imaging with CTR
PrintPeak wavenumber : 11.1 cm-1
Wavenumber width: 0.2 cm-
1
Resolution: 0.8 mm
8 mm8 mm
Transmission (%) 0 25 50 75 100
Transmission (%) 0 25 50 75 100
LeafPeak wavenumber : 10.7 cm-1
Wavenumber width: 3.5 cm-
1
Resolution: 0.8 mm
Other application
Summary
High-current electron linac
91 nC/bunch (kA peak current)
Coherent radiation from electron beams
FELs
Coherent radiation
Applications of the coherent radiation
Electron bunch shape monitor
Absorption spectroscopy
Other applications
Research Center for Radiation and RadioisotopesRIAST, Osaka Prefecture Univ. Electron accelerators 18 MeV Linac 600 keV Cockcroft-Walton accelerator Ion accelerators 3 MeV Tandem accelerator Cobalt-60 gamma ray sources 4 x 1015 Bq (105 Ci ) 4 irradiation rooms and a water pool facility Radioisotope facilities
Water pool for 60Co -ray sources
Cherenkov radiation from 60Co -ray sources installed