IPAC2013 - List of Authors (Nosochkov, Y.)

Paper	Title	Page
TUPEA085	Optics Tuning and Compensation in LCLS-II	1313
	Y. Nosochkov, T.O. Raubenheimer, M. Woodley SLAC, Menlo Park, California, USA
	Funding: Work supported by the US Department of Energy contract DE-AC02-76SF00515. The LCLS-II is a future upgrade of the Linear Coherent Light Source (LCLS) at SLAC. It will include two new Free Electron Lasers (FELs) to generate soft and hard X-ray radiation. The 2.9 km LCLS-II lattice will include 1/3 of the SLC linac located just before the existing LCLS, the 1.2 km bypass line, the bend section, the beam separation and diagnostic regions, and the FEL undulators and dump. The LCLS operation showed that occasionally the beam phase space may be significantly mismatched due to various errors in the beamline. This requires correction to ensure good beam quality in the undulators. Similarly, the LCLS-II must have lattice correction system with a large tuning range to cancel such errors. Since the various LCLS-II regions are connected using matching sections, the latter naturally can be used for correction of the mismatched lattice functions. In addition, the large tuning capability is required to provide a wide range of focusing conditions at the FEL undulators. The compensation and tuning abilities of the LCLS-II lattice have been studied for incoming beam errors equivalent to 160% of beta beat and for a factor of 5 in the range of undulator quadrupole strengths.

TUPFI016	Optimization of Triplet Quadrupoles Field Quality for the LHC High Luminosity Lattice at Collision Energy	1364
	Y. Nosochkov, Y. Cai, M.-H. Wang SLAC, Menlo Park, California, USA R. De Maria, S.D. Fartoukh, M. Giovannozzi, E. McIntosh CERN, Geneva, Switzerland
	Funding: Work supported by the European Commission within the Framework Programme 7 Capacities Specific Programme, Grant Agreement 284404; and by the US DOE contract DE-AC02-76SF00515. For the high luminosity upgrade of the LHC (HL-LHC), the beta functions at two interaction points (IP) will be significantly reduced compared to the nominal LHC lattice. This will result in much higher peak beta functions in the inner triplet (IT) quadrupoles adjacent to these IPs. The consequences are a larger beam size in these quadrupoles, higher IT chromaticity, and stronger effects of the IT field errors on dynamic aperture (DA). The IT chromaticity will be compensated using the Achromatic Telescopic Squeezing scheme. The increased IT beam size will be accommodated by installing large aperture Nb3Sn superconducting quadrupoles with 150 mm coil diameter. The field error tolerances in these magnets must satisfy the required acceptable DA while being reasonably close to realistically achievable field quality. Evaluation of the IT field errors was performed for the LHC upgrade layout version SLHCV3.01 with IT gradient of 123 T/m and IP collision beta functions of 15 cm in both planes. Dynamic aperture calculations were performed using SixTrack. Details of the optimization of the IT field errors are presented along with corrections to achieve the field quality specifications. S. Fartoukh, “An Achromatic Telescopic Squeezing (ATS) Scheme for LHC Upgrade’’, in proceedings of IPAC11, p. 2088.

TUPFI017	Evaluation of Field Quality for Separation Dipoles and Matching Section Quadrupoles for the LHC High Luminosity Lattice at Collision Energy	1367
	Y. Nosochkov, Y. Cai, M.-H. Wang SLAC, Menlo Park, California, USA R. De Maria, S.D. Fartoukh, M. Giovannozzi, E. McIntosh CERN, Geneva, Switzerland
	Funding: Work supported by the European Commission within the Framework Programme 7 Capacities Specific Programme, Grant Agreement 284404; and by the US DOE contract DE-AC02-76SF00515. The high luminosity upgrade of the LHC (HL-LHC) lattice requires new larger aperture magnets to be installed in the low-beta interaction regions (IRs). These include Nb3Sn superconducting (SC) triplet quadrupoles, Nb-Ti SC separation dipoles D1 and D2, and SC Q4 quadrupoles. The upgrade significantly reduces the beta functions at these IRs, producing higher beta functions and larger beam size in these magnets, and requiring a larger aperture. The high beta functions also increase the impact of high order field errors in these new magnets on dynamic aperture (DA). Therefore, to maintain an acceptable DA, new specifications for the magnet field quality are required. Since the IR error effects at collision are dominated by the triplets, their field quality has been studied and specified first. As a next step, the field errors were added to the D1 and D2 dipoles and Q4 quadrupoles while maintaining the triplet errors to specifications. The impact of the errors on DA has been determined in long term tracking simulations using SixTrack. The optimized field error specifications for the D1, D2 and Q4 magnets are presented. Y. Nosochkov, Y. Cai, M-H. Wang, S. Fartoukh, M. Giovannozzi, R. de Maria, E. McIntosh, “Optimization of Triplet Field Quality for the LHC High Luminosity Lattice at Collision Energy”, IPAC 2013.

TUPWO068	Performance Improvements of the SLAC Linac for the FACET Beam	2021
	F.-J. Decker, N. Lipkowitz, E. Marín, Y. Nosochkov, J. Sheppard, M.K. Sullivan, Y. Sun, M.-H. Wang, G.R. White, U. Wienands, M. Woodley, G. Yocky SLAC, Menlo Park, California, USA
	Funding: Work supported by U.S.Department of Energy, Contract DE-AC02-76SF00515. Two thirds of the SLAC Linac is used to generate a short, intense electron beam for the FACET experiments. The emittance growth along the Linac is a major concern to finally get small spot sizes for these experiments. There are two different approaches to get the required small emittances: a) lengthy iterative global tuning technique, and b) trying to identify locations of the main sources of the emittance growth and reducing their effect locally. How these approaches help to get good beam performances is discussed.

TUPWO069	Optimization of FACET Optics	2024
	M.-H. Wang, F.-J. Decker, N. Lipkowitz, Y. Nosochkov, G.R. White, U. Wienands, M. Woodley, G. Yocky SLAC, Menlo Park, California, USA
	Funding: supported by the US Department of Energy contract DE-AC02-76SF00515. The FACET accelerator facility is designed to provide short and intense e^- or e⁺ bunches with small spot size for plasma wakefield accelerator research and other experiments. It is based on the SLAC linac with a compressor chicane in sector-10, and a second compressor chicane and final focus in sector-20 (S20). Originally, the S20 chicane was designed to be compatible with an upgrade to include a second S20 chicane for simultaneous transport of e^- and e⁺ bunches. This placed additional optics constraints which lead to strong focusing in the S20 chicane. The latter increases the effects of errors causing emittance growth. Lately, it has been decided not to proceed with the upgrade option. Therefore, there is a potential for improving the optics by relaxing the constraints. In this study, we explore alternative optics designs where beta functions in the S20 chicane and final focus are reduced in order to minimize the error effects. The optics and non-linear aberrations are evaluated, and the chromatic correction is optimized for each design. Beam tracking simulations are performed using Elegant and Lucretia. The most optimal designs are identified based on these simulations.

Paper

Title

Page

Optics Tuning and Compensation in LCLS-II

1313

Y. Nosochkov, T.O. Raubenheimer, M. Woodley
SLAC, Menlo Park, California, USA

Funding: Work supported by the US Department of Energy contract DE-AC02-76SF00515.
The LCLS-II is a future upgrade of the Linear Coherent Light Source (LCLS) at SLAC. It will include two new Free Electron Lasers (FELs) to generate soft and hard X-ray radiation. The 2.9 km LCLS-II lattice will include 1/3 of the SLC linac located just before the existing LCLS, the 1.2 km bypass line, the bend section, the beam separation and diagnostic regions, and the FEL undulators and dump. The LCLS operation showed that occasionally the beam phase space may be significantly mismatched due to various errors in the beamline. This requires correction to ensure good beam quality in the undulators. Similarly, the LCLS-II must have lattice correction system with a large tuning range to cancel such errors. Since the various LCLS-II regions are connected using matching sections, the latter naturally can be used for correction of the mismatched lattice functions. In addition, the large tuning capability is required to provide a wide range of focusing conditions at the FEL undulators. The compensation and tuning abilities of the LCLS-II lattice have been studied for incoming beam errors equivalent to 160% of beta beat and for a factor of 5 in the range of undulator quadrupole strengths.

TUPFI016

Optimization of Triplet Quadrupoles Field Quality for the LHC High Luminosity Lattice at Collision Energy

1364

Y. Nosochkov, Y. Cai, M.-H. Wang
SLAC, Menlo Park, California, USA
R. De Maria, S.D. Fartoukh, M. Giovannozzi, E. McIntosh
CERN, Geneva, Switzerland

Funding: Work supported by the European Commission within the Framework Programme 7 Capacities Specific Programme, Grant Agreement 284404; and by the US DOE contract DE-AC02-76SF00515.
For the high luminosity upgrade of the LHC (HL-LHC), the beta functions at two interaction points (IP) will be significantly reduced compared to the nominal LHC lattice. This will result in much higher peak beta functions in the inner triplet (IT) quadrupoles adjacent to these IPs. The consequences are a larger beam size in these quadrupoles, higher IT chromaticity, and stronger effects of the IT field errors on dynamic aperture (DA). The IT chromaticity will be compensated using the Achromatic Telescopic Squeezing scheme*. The increased IT beam size will be accommodated by installing large aperture Nb3Sn superconducting quadrupoles with 150 mm coil diameter. The field error tolerances in these magnets must satisfy the required acceptable DA while being reasonably close to realistically achievable field quality. Evaluation of the IT field errors was performed for the LHC upgrade layout version SLHCV3.01 with IT gradient of 123 T/m and IP collision beta functions of 15 cm in both planes. Dynamic aperture calculations were performed using SixTrack. Details of the optimization of the IT field errors are presented along with corrections to achieve the field quality specifications.
* S. Fartoukh, “An Achromatic Telescopic Squeezing (ATS) Scheme for LHC Upgrade’’, in proceedings of IPAC11, p. 2088.

TUPFI017

Evaluation of Field Quality for Separation Dipoles and Matching Section Quadrupoles for the LHC High Luminosity Lattice at Collision Energy

1367

Y. Nosochkov, Y. Cai, M.-H. Wang
SLAC, Menlo Park, California, USA
R. De Maria, S.D. Fartoukh, M. Giovannozzi, E. McIntosh
CERN, Geneva, Switzerland

Funding: Work supported by the European Commission within the Framework Programme 7 Capacities Specific Programme, Grant Agreement 284404; and by the US DOE contract DE-AC02-76SF00515.
The high luminosity upgrade of the LHC (HL-LHC) lattice requires new larger aperture magnets to be installed in the low-beta interaction regions (IRs). These include Nb3Sn superconducting (SC) triplet quadrupoles, Nb-Ti SC separation dipoles D1 and D2, and SC Q4 quadrupoles. The upgrade significantly reduces the beta functions at these IRs, producing higher beta functions and larger beam size in these magnets, and requiring a larger aperture. The high beta functions also increase the impact of high order field errors in these new magnets on dynamic aperture (DA). Therefore, to maintain an acceptable DA, new specifications for the magnet field quality are required. Since the IR error effects at collision are dominated by the triplets, their field quality has been studied and specified first*. As a next step, the field errors were added to the D1 and D2 dipoles and Q4 quadrupoles while maintaining the triplet errors to specifications. The impact of the errors on DA has been determined in long term tracking simulations using SixTrack. The optimized field error specifications for the D1, D2 and Q4 magnets are presented.
* Y. Nosochkov, Y. Cai, M-H. Wang, S. Fartoukh, M. Giovannozzi, R. de Maria, E. McIntosh, “Optimization of Triplet Field Quality for the LHC High Luminosity Lattice at Collision Energy”, IPAC 2013.

TUPWO068

Performance Improvements of the SLAC Linac for the FACET Beam

2021

F.-J. Decker, N. Lipkowitz, E. Marín, Y. Nosochkov, J. Sheppard, M.K. Sullivan, Y. Sun, M.-H. Wang, G.R. White, U. Wienands, M. Woodley, G. Yocky
SLAC, Menlo Park, California, USA

Funding: Work supported by U.S.Department of Energy, Contract DE-AC02-76SF00515.
Two thirds of the SLAC Linac is used to generate a short, intense electron beam for the FACET experiments. The emittance growth along the Linac is a major concern to finally get small spot sizes for these experiments. There are two different approaches to get the required small emittances: a) lengthy iterative global tuning technique, and b) trying to identify locations of the main sources of the emittance growth and reducing their effect locally. How these approaches help to get good beam performances is discussed.

TUPWO069

Optimization of FACET Optics

2024

M.-H. Wang, F.-J. Decker, N. Lipkowitz, Y. Nosochkov, G.R. White, U. Wienands, M. Woodley, G. Yocky
SLAC, Menlo Park, California, USA

Funding: supported by the US Department of Energy contract DE-AC02-76SF00515.
The FACET accelerator facility is designed to provide short and intense e^- or e⁺ bunches with small spot size for plasma wakefield accelerator research and other experiments. It is based on the SLAC linac with a compressor chicane in sector-10, and a second compressor chicane and final focus in sector-20 (S20). Originally, the S20 chicane was designed to be compatible with an upgrade to include a second S20 chicane for simultaneous transport of e^- and e⁺ bunches. This placed additional optics constraints which lead to strong focusing in the S20 chicane. The latter increases the effects of errors causing emittance growth. Lately, it has been decided not to proceed with the upgrade option. Therefore, there is a potential for improving the optics by relaxing the constraints. In this study, we explore alternative optics designs where beta functions in the S20 chicane and final focus are reduced in order to minimize the error effects. The optics and non-linear aberrations are evaluated, and the chromatic correction is optimized for each design. Beam tracking simulations are performed using Elegant and Lucretia. The most optimal designs are identified based on these simulations.