NAPAC2016 - List of Authors (Di Mitri, S.)

Paper	Title	Page
TUB1CO02	Operating Synchrotron Light Sources with a High Gain Free Electron Laser	259
	S. Di Mitri, M. Cornacchia Elettra-Sincrotrone Trieste S.C.p.A., Basovizza, Italy
	The peak current required by a high gain free electron laser (FEL) is not deemed to be compatible with the multi-bunch filling pattern of synchrotrons. We show that this problem can be overcome by virtue of magnetic bunch length compression in a ring section and that, after lasing, the beam returns to equilibrium conditions without beam quality disruption. As a consequence of bunch length compression, the peak current stimulates a high gain FEL emission, while the large energy spread makes the beam less sensitive to the FEL heating and to the microwave instability. The beam large energy spread is matched to the FEL energy bandwidth through a transverse gradient undulator. Feasibility of lasing at 25 nm is shown for the Elettra synchrotron light source (SLS) at 1 GeV. Viable scenarios for the upgrade of existing or planned SLSs to the new hybrid insertion devices-plus-FEL operational mode are discussed, while ensuring little impact on the standard beamlines functionality. S. Di Mitri and M. Cornacchia, NJP 17 (2015) 113006
	Slides TUB1CO02 [2.353 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-NAPAC2016-TUB1CO02
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THPOA04	Maximum Brightness of Linac-Driven Electron Beams in the Presence of Collective Effects	1101
	S. Di Mitri Elettra-Sincrotrone Trieste S.C.p.A., Basovizza, Italy
	Linear accelerators capable of delivering high brightness electron beams are essential components of a number of research tools, such as free electron lasers (FELs) and elementary particle colliders. In these facilities the charge density is high enough to drive undesirable collective effects (wakefields) that may increase the beam emittance relative to the injection level, eventually degrading the nominal brightness. We formulate a limit on the final electron beam brightness, imposed by the interplay of geometric transverse wakefield in accelerating structures and coherent synchrotron radiation in energy dispersive regions. Numerous experimental data of VUV and X-ray FEL drivers validate our model. This is then used to show that a normalized brightness of 10¹⁶ A/m², promised so far by ultra-low charge beams (1-10 pC), can in fact be reached with a 100 pC charge beam in the Italian FERMI FEL linac, with the existing machine configuration.* Physical Review Special Topics - Accelerators And Beams 17, 110702 (2014) *Physical Review Special Topics - Accelerators And Beams 16, 050701 (2013)
	Poster THPOA04 [0.828 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-NAPAC2016-THPOA04
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THPOA05	Intrabeam Scattering in High Brightness Electron Linacs	1104
	S. Di Mitri Elettra-Sincrotrone Trieste S.C.p.A., Basovizza, Italy
	The role played by Intra-Beam Scattering (IBS) in high brightness electron linacs, like those driving free electron lasers, is studied analytically and with particle tracking. We found that IBS typically plays no significant role in the microbunching instability that develops in such accelerators. A partial damping of the instability through IBS is envisaged, however, with dedicated magnetic insertions. The feasibility of linear and circular lattice designs to cumulate relevant IBS-induced energy spread, and the interplay with microbunching instability, are discussed theoretically, and with the help of tracking codes. S. Di Mitri, PRST-AB 17, 074401 (2014)
	Poster THPOA05 [0.547 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-NAPAC2016-THPOA05
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THPOA06	CSR-Immune Arc Compressors for Recirculating Accelerators Driving High Brightness Electron Beams	1108
	S. Di Mitri, M. Cornacchia Elettra-Sincrotrone Trieste S.C.p.A., Basovizza, Italy
	The advent of short electron bunches in high brightness linear accelerators has raised the awareness of the accelerator community to the degradation of the beam transverse emittance by coherent synchrotron radiation (CSR) emitted in magnetic bunch length compressors, transfer lines and turnaround arcs. We reformulate the concept of CSR-driven beam optics balance, and apply it to the general case of varying bunch length in an achromatic cell. The dependence of the CSR-perturbed emittance to beam optics, mean energy, and bunch charge is shown. The analytical findings are compared with particle tracking results. Practical considerations on CSR-induced energy loss and nonlinear particle dynamics are included. As a result, we identify the range of parameters that allows feasibility of an arc compressor in a recirculating accelerator driving, for example, a free electron laser or a linear collider. S. Di Mitri and M. Cornacchia, EPL, 109 (2015) 62002 **S. Di Mitri, NIM A 806 (2016) 184'192
	Poster THPOA06 [0.616 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-NAPAC2016-THPOA06
Export •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

Paper

Title

Page

Operating Synchrotron Light Sources with a High Gain Free Electron Laser

259

S. Di Mitri, M. Cornacchia
Elettra-Sincrotrone Trieste S.C.p.A., Basovizza, Italy

The peak current required by a high gain free electron laser (FEL) is not deemed to be compatible with the multi-bunch filling pattern of synchrotrons. We show that this problem can be overcome by virtue of magnetic bunch length compression in a ring section and that, after lasing, the beam returns to equilibrium conditions without beam quality disruption*. As a consequence of bunch length compression, the peak current stimulates a high gain FEL emission, while the large energy spread makes the beam less sensitive to the FEL heating and to the microwave instability. The beam large energy spread is matched to the FEL energy bandwidth through a transverse gradient undulator. Feasibility of lasing at 25 nm is shown for the Elettra synchrotron light source (SLS) at 1 GeV. Viable scenarios for the upgrade of existing or planned SLSs to the new hybrid insertion devices-plus-FEL operational mode are discussed, while ensuring little impact on the standard beamlines functionality.
* S. Di Mitri and M. Cornacchia, NJP 17 (2015) 113006

Slides TUB1CO02 [2.353 MB]

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-NAPAC2016-TUB1CO02

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

THPOA04

Maximum Brightness of Linac-Driven Electron Beams in the Presence of Collective Effects

1101

S. Di Mitri
Elettra-Sincrotrone Trieste S.C.p.A., Basovizza, Italy

Linear accelerators capable of delivering high brightness electron beams are essential components of a number of research tools, such as free electron lasers (FELs) and elementary particle colliders. In these facilities the charge density is high enough to drive undesirable collective effects (wakefields) that may increase the beam emittance relative to the injection level, eventually degrading the nominal brightness. We formulate a limit on the final electron beam brightness, imposed by the interplay of geometric transverse wakefield in accelerating structures and coherent synchrotron radiation in energy dispersive regions*. Numerous experimental data of VUV and X-ray FEL drivers validate our model. This is then used to show that a normalized brightness of 10¹⁶ A/m², promised so far by ultra-low charge beams (1-10 pC), can in fact be reached with a 100 pC charge beam in the Italian FERMI FEL linac, with the existing machine configuration.**
*Physical Review Special Topics - Accelerators And Beams 17, 110702 (2014)
**Physical Review Special Topics - Accelerators And Beams 16, 050701 (2013)

Poster THPOA04 [0.828 MB]

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-NAPAC2016-THPOA04

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

THPOA05

Intrabeam Scattering in High Brightness Electron Linacs

1104

S. Di Mitri
Elettra-Sincrotrone Trieste S.C.p.A., Basovizza, Italy

The role played by Intra-Beam Scattering (IBS) in high brightness electron linacs, like those driving free electron lasers, is studied analytically and with particle tracking. We found that IBS typically plays no significant role in the microbunching instability that develops in such accelerators*. A partial damping of the instability through IBS is envisaged, however, with dedicated magnetic insertions. The feasibility of linear and circular lattice designs to cumulate relevant IBS-induced energy spread, and the interplay with microbunching instability, are discussed theoretically, and with the help of tracking codes.
* S. Di Mitri, PRST-AB 17, 074401 (2014)

Poster THPOA05 [0.547 MB]

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-NAPAC2016-THPOA05

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

THPOA06

CSR-Immune Arc Compressors for Recirculating Accelerators Driving High Brightness Electron Beams

1108

S. Di Mitri, M. Cornacchia
Elettra-Sincrotrone Trieste S.C.p.A., Basovizza, Italy

The advent of short electron bunches in high brightness linear accelerators has raised the awareness of the accelerator community to the degradation of the beam transverse emittance by coherent synchrotron radiation (CSR) emitted in magnetic bunch length compressors, transfer lines and turnaround arcs. We reformulate the concept of CSR-driven beam optics balance, and apply it to the general case of varying bunch length in an achromatic cell*. The dependence of the CSR-perturbed emittance to beam optics, mean energy, and bunch charge is shown. The analytical findings are compared with particle tracking results**. Practical considerations on CSR-induced energy loss and nonlinear particle dynamics are included. As a result, we identify the range of parameters that allows feasibility of an arc compressor in a recirculating accelerator driving, for example, a free electron laser or a linear collider.
*S. Di Mitri and M. Cornacchia, EPL, 109 (2015) 62002
**S. Di Mitri, NIM A 806 (2016) 184'192

Poster THPOA06 [0.616 MB]

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-NAPAC2016-THPOA06

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)