IT Accelerator Engineering Research Center ITAEC Asian Forum for Accelerators and Detectors (AFAD) 2018 An X-band Compact Electron Linac Development For A Neutron Radiography Seung-Wook Shin Department of Energy Science Sungkyunkwan University, Suwon, Korea
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An X-band Compact Electron Linac Development For A Neutron ... · WR90 Waveguide RF Window Power Supply Accelerating Section 2 E-Gun Circulator RF Window Circulator Be Target Neutron
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IT Accelerator Engineering Research Center ITAEC
Asian Forum for Accelerators and Detectors (AFAD) 2018
An X-band Compact Electron Linac Development For A Neutron Radiography
Seung-Wook ShinDepartment of Energy Science
Sungkyunkwan University, Suwon, Korea
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Asian Forum for Accelerators and Detectors (AFAD) 2018
Neutron Radiography
Typical neutron radiography images:(a) injection nozzle for diesel engines
(b) dried fish (Piranha)
“Mercure from Thalwil” statue made of Roman bronze
Image from IAEA-TECDOC-1604, Neutron Imaging: A Non-Destructive Tool for Materials Testing
(a)
(b)
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For neutron radiography 105 n/cm2/s of thermal neutron is needed. Using Photoneutron reaction tungsten target for gamma, Be target for neutron
15 MeV, ~100 uA electron linac is needed
Neutron Radiography
Reference from B J Patil, FLUKA simulation of 15 MeV linear accelerator based thermalneutron source for radiography
Neutron energy spectrum calculated at aperture and image plane
Reference from Yoon Sang Kim, Estimation of photoneutron yield in linear accelerator with different collimation systems by Geant4 and MCNPX simulation codes
Neutron yield energy beam comparison of geometry G1 and geometry G2
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Goal for the Research
High-energyX-ray
X-rayTarget
X-band, 6 MW Klystron
WR90 Waveguide
RF Window
PowerSupply
Accelerating Section 2
E-Gun
Circulator
RF Window
Circulator
BeTarget
Neutron
~60 cm
PowerDivider
Phase Shifter
AcceleratingSection 1
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Toshiba E37113 Klystron
Data from Yoshihisa Okubo, DEVELOPMENT OF AN X-BAND 6 MW PULSED KLYSTRON, Toshiba E37113 Klystron
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Parameters Value
Operating Frequency 11.9942 GHz
Input RF power (pulsed) < 5 MW
Pulse Length 4 us
Duty Factor 0.002
Output Beam Current(Pulsed Maximum) 50 mA
Average Beam Current 100 uA
Output Beam Energy 15 MeV
Effective Shunt Impedance per Unit Length 150 MΩ/m
Structure Type Side-coupled Cavity
Length of the Accelerating Structure ~ 60 cm
Requirements of the Electron Linac
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Design Process of the Electron Linac
2nd Stage 4th Stage1st Stage
Single Cell
Design
Full Cell
Design
Gathering
Information
3rd Stage
Limitations Size Thickness Length
Beam
Dynamics
SystemRequirement Beam
energy Beam
Current Beam size Frequency RF Power
Genetic algorithm adapted design
Maximize shunt
impedance
Minimize beam size
Maximize acceleration
Side-coupling
cell design
RF power coupler design
Compact Electron Linac Design
Whole cell simulation
Maximizecapture
coefficient
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Representative Cell DesignParameters to be Concerned
Fp
Accelerating Cell Optimization Total 11 parameters are controlled simultaneously in
1 cavity module during optimization process Usually optimal RF cavity design depends on designer’s
experience or can be found using parametric searching method.
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Things About Genetic AlgorithmMimicking the Nature – Biological Evolution
Mating Pool
Population
Selecting Mates
Mating Process
Offspring
New Population
Applying to Computing Algorithm
Selection
Crossover
Mutation
Generation
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Genetic AlgorithmPseudo-code of the Genetic Algorithm
Procedure of Genetic Algorithm
Set k=0;
Create an initial population P(k) – generate individuals;
Evaluate P(k);
While <the termination conditions are not met>
Set k=k+1;
Reproduce mating pool ෨𝑃(k) from P(k-1) using tournament selection;
Crossover ෨𝑃 (k) to form a tentative populationP(k);
Mutate ෨𝑃(k) to form the new population P(k);
Evaluate P(k);
End While
Output the solution;
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Genetic AlgorithmOverall Procedures of the Genetic Algorithm
Fitness Evaluation
Create Population
Selection(Reproduction)
Crossover(Recombination)
Mutation
Setting Parameters &Objective functions
Convergence Test
No
StopYes
Genetic Operations
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Genetic AlgorithmOverall Procedures of the Genetic Algorithm