Proposal for EUV
Proposal for EUV - - VUV pulse generation with VUV pulse generation with controlled carrier
controlled carrier - - envelope phase envelope phase
Zoltán Tibai *
1, György Tóth
1, Mátyás I. Mechler
2, József A. Fülöp
2, János Hebling
1,21. Institute of Physics, University of Pécs, Ifjúság ú. 6, 7624 Pécs, Hungary
2. HAS-PTE High Field Terahertz Research Group, Ifjúság ú. 6, 7624 Pécs, Hungary
* tibai@fizika.ttk.pte.hu
References
[1] F. Reiter et al., Phys. Rev. Lett. 105, 243902 (2010) [2] http://www.pulsar.nl/gpt/
[3] W.D. Kimura et al., Phys. Rev. Lett. 92, 054801 (2004)
[4] J. D. Jackson: Classical Electrodynamics 3rd ed., Wiley, ISBN 0-471-30932-X
Acknowledgement
This work was carried out with the financial support of the Hungarian Scientific Research Fund (OTKA) grant numbers 101846, the SROP-4.2.2/B-10/2/2010- 0029, and hELIos ELI_09-01-2010-0013 projects.
Institute of Physics
Deptartment of Experimental Phyisics http://physics.ttk.pte.hu
Conclusion
• A robust method for producing CEP-controlled half-cycle –few-cycle pulses in the EUV–VUV spectral range was proposed
• Shorter than 10 nm microbunch length can be achieved by using a single period undulator with an undulator period shorter than resonant one, and small undulator parameter
• Since up to tens of nJ pulse energy can be achieved, these CEP stable pulse can be used as pump in pump – probe measurements
• Generation of attosecond pulses as short as 100 as pulse is possible by the proposed method
• These pulses can be used as seed in SESA FEL
Introduction
• Generation of waveform-controlled single- or few-cycle electromagnetic pulses down to the extreme ultraviolet (EUV) wavelengths is of
considerable interest [1].
• Generation of carrier-envelope phase (CEP) stabilized fs pulses in the VIS- NIR wavelength range is well established, however there are no reliable techniques available for CEP control of attosecond pulses.
• We propose a robust method for producing CEP-controlled half-cycle – few-cycle pulses in the EUV–VUV spectral range.
The proposed setup
• The scheme of the proposed setup is shown in the figure below.
• Method based on
- ultrathin electron layer generation, - coherent undulator radiation.
• We used the General Particle Tracer (GPT) [2] numerical code for simulation of microbunching by inverse free electron laser (buncher undulator).
• We calculated the temporal shape of the electric field of the radiation generated in a second undulator (radiator undulator).
Production of ultrathin electron layers
The shortest microbunch length parameters
• Thus far the shortest microbunch length was about 800 nm [3].
• This was obtained with the following parameters:
- undulator parameter: K=3, - undulator period number: 10,
- the undulator period length satisfies the resonant condition:
Simulation results of microbunching
• In order to produce shorter microbunch length we used - smaller undulator parameter: K=0.25,
- only 1 undulator period,
- shorter than resonant undulator period (see the figure on the right).
• We used the formula of synchrotron radiation [4] to calculate the temporal shape of the electric field of the radiation generated in the radiator
undulator:
• During the radiation process the acceleration, velocity and position of the macroparticles were followed numerically by taking into account the Lorentz-force equation:
2 2 / K 1
l 2 2
u +
λ
⋅
= γ λ
( )
( )
ret R 3
R
. R
R R
4 ) q
t , r (
E 0
β
−
β
× β
−
× π
= µ
r r
r r r
r r
r
( )
z(t)B v dt q
) v m (
d r
r r
×
⋅ γ =
Scheme of the proposed setup
Our parameters
THz Thomson-scattering
• Advantages:
- lower needed electron energy - easier CEP adjustment
• Disadvantages:
- lower attosecond pulse energy - High THz pulse energy needed
Results for resonant and optimal undulator period
Comparison of radiation generated by a single-electron and an electron-bunch in the radiator undulator
Examples for pulses generated by undulator radiation (brown) and THz Thomson-scattering (green)
Generated attosecond pulse shapes with different CEP
Single-cycle attosecond pulse generation 80 nm
1 µm 600 nm
62 nm 34 nm 67 nm
λr
1.2 nJ 3.5 fs
0.5 T 16 mm
100
0.1 nJ 120 as
14 MV/cm 3 mm
100
40 nJ 1.4 fs
8 mT 54 cm
700
22 nJ 140 as
10 mT 43 cm
1960
95 as 260 as
∆t
3.5 nJ 0.2 T
39 mm 900
1.0 nJ 0.5 T
16 mm 400
Eas BU, ETHz
λu, λTHz γ
Calculation method of the electric field and results
0.72 mm Laser beam size inside buncher u.
3.89 TW Laser power
linear Laser polarization
516 nm Laser wavelength
81 cm / 41 cm Undulator period length
80 µm E-beam radius
3.2 mm mrad E-beam normalized emittance
≈ 1.8 ps E-beam pulse length (1σ)
5.04 nC E-beam charge (total pulse)
0.04 % E-beam intrinsic energy spread (1σ)
460 MeV E-beam energy
Value Parameter
