IPAC2015 - List of Authors (Popov, V.)

Paper	Title	Page
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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TUPMA012	Developing an Improved Pulsed Mode Operation for Duke Storage Ring Based FEL	1860
	S.F. Mikhailov, H. Hao, V. Popov, Y.K. Wu FEL/Duke University, Durham, North Carolina, USA
	Funding: This work is supported in part by the US DoE grant # DE-FG02-97ER41033 The Duke FEL and High Intensity Gamma-ray Source (HIGS) facility is operated with an e-beam from 0.24 to 1.2 GeV and a photon beam from 190 to 1060 nm. Currently, the energy range of the gamma-ray beam is from 1 MeV to about 100 MeV, with the maximum total gamma-ray flux about 3·10¹⁰ gammas per second around 10 MeV. The FEL is typically operated in quasi-CW mode. Some HIGS user experiments can benefit tremendously from a pulsed mode of FEL operation. For that purpose, a fast steering magnet was developed years ago to modulate the FEL gain. This FEL gain modulator decouples the e-beam from the FEL beam in the interaction region for most of time, but periodically allows a brief overlap of the electron and FEL beams. This allows us to build up a high peak power FEL pulse from a well-damped electron beam. However, the use of this gain modulator at low e-beam energies can dramatically limit e-beam current due to beam instability and poor injection. To overcome these shortcomings, we have successfully tested an RF frequency modulation technique to pulse the FEL beam. In this paper, we will describe this development, and report our preliminary results of this improved pulsed FEL operation.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-TUPMA012
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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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Paper

Title

Page

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

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

TUPMA012

Developing an Improved Pulsed Mode Operation for Duke Storage Ring Based FEL

1860

S.F. Mikhailov, H. Hao, V. Popov, Y.K. Wu
FEL/Duke University, Durham, North Carolina, USA

Funding: This work is supported in part by the US DoE grant # DE-FG02-97ER41033
The Duke FEL and High Intensity Gamma-ray Source (HIGS) facility is operated with an e-beam from 0.24 to 1.2 GeV and a photon beam from 190 to 1060 nm. Currently, the energy range of the gamma-ray beam is from 1 MeV to about 100 MeV, with the maximum total gamma-ray flux about 3·10¹⁰ gammas per second around 10 MeV. The FEL is typically operated in quasi-CW mode. Some HIGS user experiments can benefit tremendously from a pulsed mode of FEL operation. For that purpose, a fast steering magnet was developed years ago to modulate the FEL gain. This FEL gain modulator decouples the e-beam from the FEL beam in the interaction region for most of time, but periodically allows a brief overlap of the electron and FEL beams. This allows us to build up a high peak power FEL pulse from a well-damped electron beam. However, the use of this gain modulator at low e-beam energies can dramatically limit e-beam current due to beam instability and poor injection. To overcome these shortcomings, we have successfully tested an RF frequency modulation technique to pulse the FEL beam. In this paper, we will describe this development, and report our preliminary results of this improved pulsed FEL operation.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-TUPMA012

Export •

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

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

Export •

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