1NCKU, Oct. 13, 2008
Department of Electrical Engineering/Institute of Photonics
Technologies/ Department of Physics 1National Tsinghua University,
Hsinchu, Taiwan
2National Synchrotron Radiation Research Center Hsinchu,
Taiwan
We gratefully acknowledge financial supports from NSRRC, CSIST,
NSC, and NTHU.
• Facility Overview
HOPE Laboratory Building
• Proposed in Spring, 1998, commissioned in Spring, 2008 • a
4-story building with a total area of 13,000 ft2. (3501,155 m2) •
Dedicated to advanced particle acceleration and radiation.
Low & Intermediate-energy Laser Lab Others under planning
High-energy Laser Lab Nano-, μ-Fab Cleanroom
Accelerator/FEL Facility
Collaboration Network
Russia Academic of Science (High power microwave)
Luo
Liang
Wiedemann
Pantell
Byer
(Halloween photo)
(Gwo-Huei Luo, NSRRC) (Wai-Keung Lau, NSRRC) (Tai-Ching Fan, NSRRC)
(Kung LinLiu, NSRRC)
(Yen-Chieh Huang, NTHU) (Fan-Yi Lin, NTHU) (Yen-Yin Lin,NTHU)
(Sidney S. Yang, NTHU)
(Yen-Hung Chen, NCU) (Ming Chen, NTHU/CSIST)
NSRRCNTHU/CSIST/NCU
Liang Mezzanine
Shu Mezzanine
Fourth Floor
Advanced Teaching Lab
Sketch of On-going Programs
1. S-band THz-pulse-train Photoinjector (collaborating with of
NSRRC)
2. TW-power, THz-pulse-train laser (collaborating with of
NSRRC)
3. Superradiance Free-electron Laser (FEL) (1) MW Desktop
superradiance THz FEL
(collaborating with of NSRRC) (2) mW miniature superradiance THz
Smith-Purcell FEL
(collaborating with of NSRRC)
4. GW X-band relativistic backward-wave oscillator (collaborating
with CSIST)
Photocathode gun
High-power test
THz-pulse-train Photoinjector
loading
TW-power, THz- pulse train laser
TW-Power, THz-pulse-train Laser System (10 Hz and GHz pulse-train
are also available)
1-0.1 ps
15 ps
1
ωd dWRadiation spectral energy
W : radiation energy ω: radiation frequency μ0: vacuum permeability
q: charge t: time variable Ω: solid angle
Tutorial on Electron Radiation
For undulator with period Nu
1
2
2
θcosgΛ
) 22
θ γ
λ + Λ
m g
λ: wavelength Λg : grating period c: vacuum wave velocity ve :
electron velocity m: integer
t = 0
t = τ
t = τ
ωω rr
ri : position of ith electron k = 2π/λr: wave number λr: radiation
wavelength N: number of electrons
View at a constant location
View at a constant time
superradiance
N N
Superradiance from an electron bunch train
Radiation Spectrum
Desktop THz Superradiance FEL (space-charge force making a THz SASE
FEL difficult)
6-MeV Photocathode gun FEL
Laser
MW power at THz
Comparison: PEGASUS FEL (P ~300 kW @ 2 m with gamma = 35, λ = 13
μm, Ipeak= 134 A…) UCLA - under construction Infrared Free-Electron
Laser. The space charge forces prevents saturation within the 2m
undulator length.
Solenoid
Stanford superconducting solenoid wiggler
4
FEL Output PowerGENESIS Simulation
Beam Parameters Mean Energy 6.3 MeV rms Energy spread 0.3% Initial
Beam radius 0.15 mm Beam emittance 5.3πmm mrad peak current 100 A
Initial bunching factor 0.2 Helical Undulator Parameters Undulator
period 1.5 cm Undulator type helical Undulator parameter 0.82
Section length 1 m Resonant wavelength 76μm (3.94 THz)
0 0.2 0.4 0.6 0.8 1 1.2 1.4
0.2
0.25
0.3
0.35
0.4
0.45
0.5
0.55
0.6
0.65
Miniature THz Smith-Purcell FEL
THz radiation THz radiation
Power enhancement factor ~104-6 (!) from the pre-bunched beam
Lithographically fabricated by et al. of NSRRC
Smith-Purcell Gratings
Λ = 120 μm
For ne = 1018/cm3, Ez ~100 GV/m or 1 GeV/cm!
Ee− e− e−
laser
Hard x-ray @ 1 Å
N
S
Relativistic Nonlinear Optics Group RENO Group
Classic Nonlinear Optics Group CASINO Group
Openings for postdocs and PhD students Contact info:
[email protected]
E e− e− e−e− e−
τp
E~100 GV/m!
HUANG LAB, NTHU
http://www.hope.nthu.edu.tw LAB OF EXCELLENCE
