IPAC2015 - List of Authors (Li, J.Y.)

Paper	Title	Page
TUPMA014	Extending OK5 Wiggler Operational Limit at Duke FEL/HIGS Facility	1863
	P.W. Wallace, M. Emamian, H. Hao, J.Y. Li, S.F. Mikhailov, V. Popov, Y.K. Wu FEL/Duke University, Durham, North Carolina, USA J.Y. Li USTC/NSRL, Hefei, Anhui, People's Republic of China
	Funding: This work is supported in part by the US DOE grant no. DE-FG02-97ER41033 Since 2007 the HIGS facility has been operated to produce both linearly and circularly polarized gamma-ray beams using two FELs, the planar OK-4 FEL and helical OK-5 FEL. Presently, with the OK-5 FEL operating at 192 nm, we can produce circularly-polarized gamma-ray beams between 1 and 100 MeV for user applications. Gamma-ray production between 80 and 100 MeV required an extension of the OK-5 wiggler operation beyond the designed current limit of 3.0 kA. In 2009, we upgraded cooling and machine protection systems to successfully extend OK-5 operation to 3.5 kA. To realize HIGS gamma-ray operation beyond 100 MeV and ultimately toward 150 MeV (the pion-threshold energy), with various limitations of the VUV mirror technology, the OK-5 wigglers will need to be operated at an even higher current, between 3.6 and 4.0 kA. In this paper we present our technical solution to further extend the operation range of the OK-5 wigglers, and report our preliminary results with high-current wiggler operation.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-TUPMA014
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MOPJE003	Measuring Duke Storage Ring Lattice Using Tune Based Technique	293
	W. Li, J.Y. Li USTC/NSRL, Hefei, Anhui, People's Republic of China H. Hao, W. Li, S.F. Mikhailov, V. Popov, Y.K. Wu FEL/Duke University, Durham, North Carolina, USA
	Funding: This work is supported in part by the US DOE grant no. DE-FG02-97ER41033. The Duke electron storage ring is a dedicated driver for oscillator Free-Electron Lasers (FELs). A 34 m long straight section of the storage ring is used to host up to four FEL wigglers in several different configurations. A total of six wigglers, two planar OK-4 wigglers and four helical OK-5 wigglers, are available for FEL research. The storage ring magnetic lattice has to be designed with great flexibility to enable the storage ring operation with different FEL wigglers, at various wiggler settings, and for different electron beam energies. Since 2012, the storage ring has demonstrated all designed characteristics in terms of lattice flexibility and tuning. This work is aimed at gaining better understanding of the real storage ring lattice by performing a series of measurements of the beta-functions along the storage ring. Unlike the LOCO technique, the beta-functions in the quadrupoles are directly measured with good accuracy using a tune meassurement system. We will describe our experimental design and techniques, and measurement procedures. We will also report our preliminary results for the lattice characterization.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-MOPJE003
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MOPMA053	Characterizing Betatron Tune Knobs on Duke Storage Ring	672
	H. Hao, S.F. Mikhailov, V. Popov, Y.K. Wu FEL/Duke University, Durham, North Carolina, USA J.Y. Li USTC/NSRL, Hefei, Anhui, People's Republic of China
	Funding: This work is supported in part by the US DOE grant no. DE-FG02-97ER41033. The Duke electron storage ring is a dedicated driver for oscillator Free-Electron Lasers (FELs). A 34-m long straight section of the storage ring can host up to four FEL wigglers in several different configurations. The storage ring magnetic lattice has designed with great flexibility to enable the operation with different wiggler configurations and at different electron beam energies. To realize smooth storage ring operation with various electron beam and wiggler parameters, a sophisticated lattice feedforward compensation scheme and a set of betatron tune knobs have been designed, developed and implemented in the controls system. The built-in compensation and tune knobs have demonstrated to be highly useful to allow transparent operation of the storage ring. To fully understand the effectiveness of the lattice tuning scheme, experiments have been carried to characterize the betatron tune knobs. In this paper, we will outline the measurement techniques and procedures, report experimental results, and make important observations on the usefulness of developing an advanced light source storage ring using accurate knowledge of individual magnets with high-quality measured fields.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-MOPMA053
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MOPWI022	Experimental Study of a Two-Color Storage Ring FEL	1198
	J. Yan, H. Hao, S.F. Mikhailov, V. Popov, Y.K. Wu FEL/Duke University, Durham, North Carolina, USA S. Huang PKU, Beijing, People's Republic of China J.Y. Li USTC/NSRL, Hefei, Anhui, People's Republic of China N. Vinokurov BINP SB RAS, Novosibirsk, Russia J. Wu SLAC, Menlo Park, California, USA
	Funding: This work is supported in part by the US DOE grant no. DE-FG02-97ER41033. Multi-color Free-electron Lasers (FELs) have been developed on linac based FELs over the past two decades. On the storage ring, the optical klystron (OK) FEL in its early days was demonstrated to produce lasing at two adjacent wavelengths with their spectral separation limited by the bandwidth of single wiggler radiation. Here, we report a systematic experimental study on the two-color operation at the Duke FEL facility, the first experimental demonstration of a tunable two-color harmonic FEL operation of a storage ring based FEL. We demonstrate a simultaneous generation of two FEL wavelengths, one in infrared (IR) and the other in ultraviolet (UV) with a harmonic relationship. The experimental results show a good performance of the two-color FEL operation in terms of two-color wavelength tunability, power tunability and power stability.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-MOPWI022
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TUPJE015	Beta Function Matching and Tune Compensation for HLS-II Insertion Devices	1647
	B. Li, J.Y. Li, W. Xu, K. Xuan USTC/NSRL, Hefei, Anhui, People's Republic of China
	In order to increase its brightness and improve the performance, the Hefei Light Source (HLS) was completely renovated from 2010 to the end of 2014. The magnet lattice of the new storage ring consists of four double bend achromatic (DBA) cells. There are eight straight sections which can be used to install up to 6 insertion devices (IDs). Currently, five insertion devices have been installed in the storage ring. It is known that the dynamics of the electron beam motion in the storage ring would be influenced by the insertion device, depending on its physical properties. In order to keep high performance operation of the storage ring and make the insertion device transparent to the rest of the storage ring, a complex compensation scheme is developed to match the beta functions at both ends of a ID and perform transverse tune compensation. This scheme has been integrated into the EPICS based control system of the HLS-II. The result indicates that the scheme is very effective to compensate the impact of the insertion devices.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-TUPJE015
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Paper

Title

Page

Extending OK5 Wiggler Operational Limit at Duke FEL/HIGS Facility

1863

P.W. Wallace, M. Emamian, H. Hao, J.Y. Li, S.F. Mikhailov, V. Popov, Y.K. Wu
FEL/Duke University, Durham, North Carolina, USA
J.Y. Li
USTC/NSRL, Hefei, Anhui, People's Republic of China

Funding: This work is supported in part by the US DOE grant no. DE-FG02-97ER41033
Since 2007 the HIGS facility has been operated to produce both linearly and circularly polarized gamma-ray beams using two FELs, the planar OK-4 FEL and helical OK-5 FEL. Presently, with the OK-5 FEL operating at 192 nm, we can produce circularly-polarized gamma-ray beams between 1 and 100 MeV for user applications. Gamma-ray production between 80 and 100 MeV required an extension of the OK-5 wiggler operation beyond the designed current limit of 3.0 kA. In 2009, we upgraded cooling and machine protection systems to successfully extend OK-5 operation to 3.5 kA. To realize HIGS gamma-ray operation beyond 100 MeV and ultimately toward 150 MeV (the pion-threshold energy), with various limitations of the VUV mirror technology, the OK-5 wigglers will need to be operated at an even higher current, between 3.6 and 4.0 kA. In this paper we present our technical solution to further extend the operation range of the OK-5 wigglers, and report our preliminary results with high-current wiggler operation.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-TUPMA014

Export •

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

MOPJE003

Measuring Duke Storage Ring Lattice Using Tune Based Technique

293

W. Li, J.Y. Li
USTC/NSRL, Hefei, Anhui, People's Republic of China
H. Hao, W. Li, S.F. Mikhailov, V. Popov, Y.K. Wu
FEL/Duke University, Durham, North Carolina, USA

Funding: This work is supported in part by the US DOE grant no. DE-FG02-97ER41033.
The Duke electron storage ring is a dedicated driver for oscillator Free-Electron Lasers (FELs). A 34 m long straight section of the storage ring is used to host up to four FEL wigglers in several different configurations. A total of six wigglers, two planar OK-4 wigglers and four helical OK-5 wigglers, are available for FEL research. The storage ring magnetic lattice has to be designed with great flexibility to enable the storage ring operation with different FEL wigglers, at various wiggler settings, and for different electron beam energies. Since 2012, the storage ring has demonstrated all designed characteristics in terms of lattice flexibility and tuning. This work is aimed at gaining better understanding of the real storage ring lattice by performing a series of measurements of the beta-functions along the storage ring. Unlike the LOCO technique, the beta-functions in the quadrupoles are directly measured with good accuracy using a tune meassurement system. We will describe our experimental design and techniques, and measurement procedures. We will also report our preliminary results for the lattice characterization.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-MOPJE003

Export •

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

MOPMA053

Characterizing Betatron Tune Knobs on Duke Storage Ring

672

H. Hao, S.F. Mikhailov, V. Popov, Y.K. Wu
FEL/Duke University, Durham, North Carolina, USA
J.Y. Li
USTC/NSRL, Hefei, Anhui, People's Republic of China

Funding: This work is supported in part by the US DOE grant no. DE-FG02-97ER41033.
The Duke electron storage ring is a dedicated driver for oscillator Free-Electron Lasers (FELs). A 34-m long straight section of the storage ring can host up to four FEL wigglers in several different configurations. The storage ring magnetic lattice has designed with great flexibility to enable the operation with different wiggler configurations and at different electron beam energies. To realize smooth storage ring operation with various electron beam and wiggler parameters, a sophisticated lattice feedforward compensation scheme and a set of betatron tune knobs have been designed, developed and implemented in the controls system. The built-in compensation and tune knobs have demonstrated to be highly useful to allow transparent operation of the storage ring. To fully understand the effectiveness of the lattice tuning scheme, experiments have been carried to characterize the betatron tune knobs. In this paper, we will outline the measurement techniques and procedures, report experimental results, and make important observations on the usefulness of developing an advanced light source storage ring using accurate knowledge of individual magnets with high-quality measured fields.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-MOPMA053

Export •

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

MOPWI022

Experimental Study of a Two-Color Storage Ring FEL

1198

J. Yan, H. Hao, S.F. Mikhailov, V. Popov, Y.K. Wu
FEL/Duke University, Durham, North Carolina, USA
S. Huang
PKU, Beijing, People's Republic of China
J.Y. Li
USTC/NSRL, Hefei, Anhui, People's Republic of China
N. Vinokurov
BINP SB RAS, Novosibirsk, Russia
J. Wu
SLAC, Menlo Park, California, USA

Funding: This work is supported in part by the US DOE grant no. DE-FG02-97ER41033.
Multi-color Free-electron Lasers (FELs) have been developed on linac based FELs over the past two decades. On the storage ring, the optical klystron (OK) FEL in its early days was demonstrated to produce lasing at two adjacent wavelengths with their spectral separation limited by the bandwidth of single wiggler radiation. Here, we report a systematic experimental study on the two-color operation at the Duke FEL facility, the first experimental demonstration of a tunable two-color harmonic FEL operation of a storage ring based FEL. We demonstrate a simultaneous generation of two FEL wavelengths, one in infrared (IR) and the other in ultraviolet (UV) with a harmonic relationship. The experimental results show a good performance of the two-color FEL operation in terms of two-color wavelength tunability, power tunability and power stability.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-MOPWI022

Export •

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

TUPJE015

Beta Function Matching and Tune Compensation for HLS-II Insertion Devices

1647

B. Li, J.Y. Li, W. Xu, K. Xuan
USTC/NSRL, Hefei, Anhui, People's Republic of China

In order to increase its brightness and improve the performance, the Hefei Light Source (HLS) was completely renovated from 2010 to the end of 2014. The magnet lattice of the new storage ring consists of four double bend achromatic (DBA) cells. There are eight straight sections which can be used to install up to 6 insertion devices (IDs). Currently, five insertion devices have been installed in the storage ring. It is known that the dynamics of the electron beam motion in the storage ring would be influenced by the insertion device, depending on its physical properties. In order to keep high performance operation of the storage ring and make the insertion device transparent to the rest of the storage ring, a complex compensation scheme is developed to match the beta functions at both ends of a ID and perform transverse tune compensation. This scheme has been integrated into the EPICS based control system of the HLS-II. The result indicates that the scheme is very effective to compensate the impact of the insertion devices.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-TUPJE015

Export •

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