FEL2014 - List of Keywords (lattice)

Paper	Title	Other Keywords	Page
MOP001	Particle Tracking Simulations for EXFEL Complex shape Collimators	electron, radiation, simulation, photon	22
	V.G. Khachatryan, V.H. Petrosyan, T.L. Vardanyan CANDLE SRI, Yerevan, Armenia
	The study sets the objective to investigate through numerical simulation the produced secondary radiation properties when the electron beam particles hit collimator walls. Using particle tracking simulation code FLUKA, the European XFEL electron beam as well as beam halo interaction with the collimator were simulated. The complex geometrical shape and material composition of the collimator have been taken into account. Absorbed dose spatial distribution in the material of the collimators and particle fluencies from the downstream surface of the collimator were simulated for the total secondary radiation and its main components.

TUP019	Update on the FEL Code Genesis 1.3	electron, undulator, radiation, FEL	403
	S. Reiche PSI, Villigen PSI, Switzerland
	The widely used time-dependent code Genesis 1.3 has been modified to address new needs of users worldwide. The existing limitation of tracking isolated slices of the FEL beam has been overcome by keeping the entire electron beam in memory, which is tracked as a whole through the undulator. This modification allows for additional features such as allowing particles to migrate into other slices or applying self-consistent wakefield and space charge models.

THP012	Error Analysis for Linac Lattice of Hard X-ray FEL Line in PAL-XFEL*	emittance, linac, simulation, alignment	703
	H. Yang, J.H. Han, H.-S. Kang, I.S. Ko PAL, Pohang, Kyungbuk, Republic of Korea
	Funding: *This work was supported by MSIP, Korea. PAL-XFEL consists of the hard x-ray line for 0.06 – 1-nm FEL and the soft x-ray line for 1 – 10-nm FEL. The linac of hard x-ray line is designed to generate 10-GeV, 200-pC, and 3-kA electron beam. It consists of S-band accelerating columns, an X-band linearizer, three bunch compressors (BC). We conduct error simulation in order to evaluate the tolerances of machine parameters and alignments. First, the machine tolerances and beam jitter levels are calculated in the simulations with dynamic errors and we find out the optimized lattice to satisfy the target tolerance of machine. Second, we conduct simulations with misalignment. We quantify the emittance dilution by misalignments, especially those of BCs. In order to compensate the misalignments, the methods of beam correction like Beam Based Alignment (BBA) are presented and the effects of emittance improvements are calculated.
	Poster THP012 [0.736 MB]

THP016	Optimization of FEL Performanceby Dispersion-based Beam-tilt Correction	FEL, simulation, electron, radiation	714
	M.W. Guetg, S. Reiche PSI, Villigen PSI, Switzerland
	In Free Electron Lasers (FEL) the beam quality is of crucial importance for the radiation power. A transverse centroid misalignment of longitudinal slices in an electron bunch reduces the effective overlap between radiation field and electron bunch. This leads to a reduced bunching and decreased FEL performance. The dominant sources of slice misalignments in FELs are the coherent synchrotron radiation within bunch compressors as well as transverse wake fields in the accelerating cavities. This is of particular importance for over-compression, which is required for one of the key operation modes for the SwissFEL under construction at the Paul Scherrer Institute in Switzerland. The slice centroid shift can be corrected using multi-pole magnets in dispersive sections, e.g. the bunch compressors. First and second order corrections are achieved by pairs of sextupole and quadrupole magnets in the horizontal plane while skew quadrupoles correct to first order in the vertical plane.

THP022	Theoretical Investigation of Coherent Synchrotron Radiation Induced Microbunching Instability in Transport and Recirculation Arcs	emittance, recirculation, damping, electron	730
	C.-Y. Tsai Virginia Polytechnic Institute and State University, Blacksburg, Virginia, USA D. Douglas, R. Li, C. Tennant JLab, Newport News, Virginia, USA
	Funding: This work is supported by Jefferson Science Associates, LLC under U.S. DOE Contract No. DE-AC05-06OR23177. The coherent synchrotron radiation (CSR) of a high brightness electron beam traversing a series of dipoles, such as recirculation or transport arcs, may lead to the microbunching instability. We extend and develop a semi-analytical approach of the CSR-induced microbunching instability for a general lattice, based on the previous formulation with 1-D CSR model [Phys. Rev. ST Accel. Beams 5, 064401 (2002)] and apply it to investigate the physical processes of microbunching amplification for two example transport arc lattices. We find that the microbunching instability in transport arcs has a distinguishing feature of multistage amplification (e.g, up to 6th stage for our example arcs in contrast to two stage amplification for a 3-dipole chicane). By further extending the concept of stage gain as proposed by Huang and Kim [Phys. Rev. ST Accel. Beams 5, 074401 (2002)], we developed a method to quantitatively characterize the microbunching amplification in terms of iterative or staged orders that allows the comparison of optics impacts on microbunching gain for different lattices. The parametric dependencies and Landau damping for our example lattices are also studied. Excellent agreement of the gain functions and spectra from Vlasov analysis with results from ELEGANT is achieved which helps to validate our analyses.
	Poster THP022 [1.316 MB]

Paper

Title

Other Keywords

Page

MOP001

Particle Tracking Simulations for EXFEL Complex shape Collimators

electron, radiation, simulation, photon

22

V.G. Khachatryan, V.H. Petrosyan, T.L. Vardanyan
CANDLE SRI, Yerevan, Armenia

The study sets the objective to investigate through numerical simulation the produced secondary radiation properties when the electron beam particles hit collimator walls. Using particle tracking simulation code FLUKA, the European XFEL electron beam as well as beam halo interaction with the collimator were simulated. The complex geometrical shape and material composition of the collimator have been taken into account. Absorbed dose spatial distribution in the material of the collimators and particle fluencies from the downstream surface of the collimator were simulated for the total secondary radiation and its main components.

TUP019

Update on the FEL Code Genesis 1.3

electron, undulator, radiation, FEL

403

S. Reiche
PSI, Villigen PSI, Switzerland

The widely used time-dependent code Genesis 1.3 has been modified to address new needs of users worldwide. The existing limitation of tracking isolated slices of the FEL beam has been overcome by keeping the entire electron beam in memory, which is tracked as a whole through the undulator. This modification allows for additional features such as allowing particles to migrate into other slices or applying self-consistent wakefield and space charge models.

THP012

Error Analysis for Linac Lattice of Hard X-ray FEL Line in PAL-XFEL*

emittance, linac, simulation, alignment

703

H. Yang, J.H. Han, H.-S. Kang, I.S. Ko
PAL, Pohang, Kyungbuk, Republic of Korea

Funding: *This work was supported by MSIP, Korea.
PAL-XFEL consists of the hard x-ray line for 0.06 – 1-nm FEL and the soft x-ray line for 1 – 10-nm FEL. The linac of hard x-ray line is designed to generate 10-GeV, 200-pC, and 3-kA electron beam. It consists of S-band accelerating columns, an X-band linearizer, three bunch compressors (BC). We conduct error simulation in order to evaluate the tolerances of machine parameters and alignments. First, the machine tolerances and beam jitter levels are calculated in the simulations with dynamic errors and we find out the optimized lattice to satisfy the target tolerance of machine. Second, we conduct simulations with misalignment. We quantify the emittance dilution by misalignments, especially those of BCs. In order to compensate the misalignments, the methods of beam correction like Beam Based Alignment (BBA) are presented and the effects of emittance improvements are calculated.

Poster THP012 [0.736 MB]

THP016

Optimization of FEL Performanceby Dispersion-based Beam-tilt Correction

FEL, simulation, electron, radiation

714

M.W. Guetg, S. Reiche
PSI, Villigen PSI, Switzerland

In Free Electron Lasers (FEL) the beam quality is of crucial importance for the radiation power. A transverse centroid misalignment of longitudinal slices in an electron bunch reduces the effective overlap between radiation field and electron bunch. This leads to a reduced bunching and decreased FEL performance. The dominant sources of slice misalignments in FELs are the coherent synchrotron radiation within bunch compressors as well as transverse wake fields in the accelerating cavities. This is of particular importance for over-compression, which is required for one of the key operation modes for the SwissFEL under construction at the Paul Scherrer Institute in Switzerland. The slice centroid shift can be corrected using multi-pole magnets in dispersive sections, e.g. the bunch compressors. First and second order corrections are achieved by pairs of sextupole and quadrupole magnets in the horizontal plane while skew quadrupoles correct to first order in the vertical plane.

THP022

Theoretical Investigation of Coherent Synchrotron Radiation Induced Microbunching Instability in Transport and Recirculation Arcs

emittance, recirculation, damping, electron

730

C.-Y. Tsai
Virginia Polytechnic Institute and State University, Blacksburg, Virginia, USA
D. Douglas, R. Li, C. Tennant
JLab, Newport News, Virginia, USA

Funding: This work is supported by Jefferson Science Associates, LLC under U.S. DOE Contract No. DE-AC05-06OR23177.
The coherent synchrotron radiation (CSR) of a high brightness electron beam traversing a series of dipoles, such as recirculation or transport arcs, may lead to the microbunching instability. We extend and develop a semi-analytical approach of the CSR-induced microbunching instability for a general lattice, based on the previous formulation with 1-D CSR model [Phys. Rev. ST Accel. Beams 5, 064401 (2002)] and apply it to investigate the physical processes of microbunching amplification for two example transport arc lattices. We find that the microbunching instability in transport arcs has a distinguishing feature of multistage amplification (e.g, up to 6th stage for our example arcs in contrast to two stage amplification for a 3-dipole chicane). By further extending the concept of stage gain as proposed by Huang and Kim [Phys. Rev. ST Accel. Beams 5, 074401 (2002)], we developed a method to quantitatively characterize the microbunching amplification in terms of iterative or staged orders that allows the comparison of optics impacts on microbunching gain for different lattices. The parametric dependencies and Landau damping for our example lattices are also studied. Excellent agreement of the gain functions and spectra from Vlasov analysis with results from ELEGANT is achieved which helps to validate our analyses.

Poster THP022 [1.316 MB]