Transcript No Slide Title

Started 1 May 99
October 1999
An X-Band Photoinjector for Intense
MM-Wave and Tunable X-Ray Generation
E.C. Landahl, H. A. Baldis, J.E. Boggan, D. Gibson, F.V. Hartemann, J.P. Heritage,
C.H. Ho(a), K. Li, E. Schamiloglu(b), A.L. Troha, N.C. Luhmann, Jr.
University of California, Davis, CA 95616
Lawrence Livermore National Laboratory, Livermore, CA 94550
(a) Synchrotron Radiation Research Center, Hsinchu, Taiwan
(b) Department of Electrical and Computer Engineering, University of New Mexico
MVE MURI 99 Kick-off Meeting
R. Barker, Technical Monitor
Chirped-Pulse Free-Electron Maser
Started 1 May 99
Bunch Energy
Bunch Charge
Bunch Length
Wiggler Period
Wiggler Strength
Number of Wiggler Periods
Waveguide Cutoff
Peak Power
Instantaneous Bandwidth
MVE MURI 99 Kick-off Meeting
October 1999
5 MeV
1.4 nC
0.3 mm
30 mm
8.5 kG
10
40 GHz
> 2 MW
100 – 200 GHz
Smith-Purcell Maser (in collaboration with UNM)
Seed
Pulse
Amplified Output Pulse
Pre-bunched
Electron
Beam
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Diffraction Grating
UC Davis X-Band Photoinjector
Started 1 May 99
October 1999
Beam Energy
5.7 MeV
Coupled RF Power
16 MW
Bunch Duration
0.9 ps FWHM Gaussian
Bunch Charge
0.1 nC / 1.0 nC
Normalized Emittance
0.7  mm-mrad / 2.5  mm-mrad
Energy Spread
0.25 %
Laser Spot Size
0.67 mm HWHM Gaussian
MVE MURI 99 Kick-off Meeting
R. Barker, Technical Monitor
15 MW X-Band RF System
Started 1 May 99
October 1999
Pulse Amplitude
Tuning Curve
MVE MURI 99 Kick-off Meeting
R. Barker, Technical Monitor
Recent X-Band RF Gun Results
Started 1 May 99
October 1999
1
0.3
0.8
0.25
0.2
0.6
0.15
0.4
0.1
Full Cell
0.05
0.2
1/2 Cell
0
8.535
8.54
8.545 8.55 8.555
Frequency (GHz)
150
Mixer Signal (mV)
0
8.56
In Phase
100
8552
Normalized Coupled Power
Reflected Power (a.u.)
0.35

50
0
-50
Resonant Frequency (MHz)
-100
8551
Gun Probes Signal
8550
-150
8549
0
8548
8547
20
25
30
35
40
45
Temperature (C)
50
55
MVE MURI 99 Kick-off Meeting
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100
200
Phase (degrees)
300
400
Compact Tunable X-Ray Source for Biomedical
Applications is a Spin-Off of MURI Funded Research
Started 1 May 99
October 1999
The photoinjector parameters are
also optimal for x-ray generation
N N
N x rays  f e L  c
Area
Bx rays ~
I
6
Facilities developed for FEL research are currently being upgraded
MVE MURI 99 Kick-off Meeting
R. Barker, Technical Monitor
High Brightness X-Rays for Medicine
Started 1 May 99
October 1999
“Brightness” is the Figure Of Merit for electromagnetic radiation sources in many applications
The brightness of a light source determines how much spectral power can be delivered to a particular volume
Brightness = Photons/second/area/solid-angle/bandwidth
Blackbody Radiation
Bremsstrahlung
Spontaneous Emission
(Low Brightness Sources)
Lasers
(High Brightness Sources)
The Compton scattering x-ray
source uses relativistic electrons
moving in response to applied
EM fields in a manner similar to
synchrotrons except that lasers
rather than magnets provide the
“wiggler” field to create discrete
x-ray energies
Existing medical x-ray sources
combine bremsstrahlung
(radiation by electrons as they
slow down while passing through
material) with K-shell emission
lines and result in a wide x-ray
energy spectrum
MVE MURI 99 Kick-off Meeting
Synchrotron Radiation
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High Brightness X-Rays for Medicine
Started 1 May 99
October 1999
•The utility of high brightness x-rays for medical imaging has been demonstrated at synchrotron radiation facilities
Breast tissue biopsy study
(Reproduced from Radiology
1995; 195:239-244;
permission courtesy of M.
Gambaccini)
X-ray imaging using a conventional x-ray source (left); the same
sample examined using synchrotron radiation showing considerably
more detail (right)
•Early detection of small cancers enhances significantly the probability for successful treatment and recovery
•Additional advanced imaging and treatment methods may be developed with high brightness x-rays, including
subtraction imaging with Contrast Enhancing Media, chemical tagging (via monoclonal antibodies or other
chemical markers), phase-contrast imaging, x-ray phototherapy, and gamma-ray “scalpels”
MVE MURI 99 Kick-off Meeting
R. Barker, Technical Monitor
Started 1 May 99
Development of a Compact
Compton Scattering X-Ray Source
October 1999
Existing high-brightness x-ray sources either do not
provide the required x-ray energies and average
powers for medical applications (e.g. plasma x-ray
lasers) or are too large and expensive for use in a
clinical environment (synchrotrons, shown at left)
1/2 mile
High brightness x-rays are also critical to advances
in surface science and protein crystallography,
among other fields.
30 feet
Developments in high-gradient, high-frequency
electron accelerators and synchronized state-of-the-art
high peak power ultrashort lasers are being combined
to create a clinically feasible high brightness x-ray
source in our laboratory at LLNL.
10 feet
Advanced Photon Source, Argonne, IL
The emphasis on compact systems in the MURI
program (efficient lasers, high gradient accelerators) is
a feature of our x-ray effort which is important to the
medical community.
MVE MURI 99 Kick-off Meeting
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