IPAC2012 - List of Authors (Sasaki, S.)

Paper	Title	Page
MOPPP064	Challenges of Quasiperiodic APPLE Undulators	705
	J. Bahrdt HZB, Berlin, Germany S. Sasaki HSRC, Higashi-Hiroshima, Japan
	APPLE undulators have become workhorses in many synchrotron radiation facilities for the production of variably polarized light. In helical mode higher harmonics are not produced. In linear mode (horizontal, vertical, inclined) higher harmonics may contaminate the first harmonic and spoil the quality of experimental data. Planar undulators employing a quasiperiodic magnetic structure have been built and they are successfully operated at several places. The implementation of a quasiperiodic lattice in an APPLE undulator is more complicated since the device is operated in various modes of operation. The proposed APS-upgrade includes a quasiperiodic APPLE undulator which is intended to be operated in the range 2.4-27 keV. A detailed analysis of the magnetic and spectral performance of this device is presented.

MOPPP072	Performance of APPLE-II Type Quasi-Periodic Undulator at HiSOR	729
	S. Sasaki, M. Arita, K. Goto, A. Miyamoto, T. Okuda HSRC, Higashi-Hiroshima, Japan
	A 1.8-m-long 78-mm-period quasi-periodic APLPE-II undulator was installed in the 700-MeV HiSOR storage ring of Hiroshima Synchrotron Radiation Center. At 23-mm nominal minimum gap, the fundamental photon energies are 3.1 eV, 6.5 eV, and 4.8 eV for horizontal linear, vertical linear, and circular polarization, respectively. The photon energies of observed fundamental and higher harmonic radiations are in good agreement with those of model calculations using measured undulator field and the HiSOR beam parameters. Also, observed flux thorough a slit and a grating monochromator was more than twice larger than that from previously installed 100-mm-period helical undulator for the whole range of radiation spectra. The feedforward COD correction was done to avoid the intensity fluctuation of photon beam in other BM beamlines due to the gap and phase motion of undulator. No fatal effect on the stored electron beam by installing the undulator was observed though a slight beam size change was observed at the minimum gap.

TUPPP014	HiSOR-II, Compact Light Source with a Torus-knot Type Accumulator Ring	1635
	A. Miyamoto, S. Sasaki HSRC, Higashi-Hiroshima, Japan
	Funding: This work is partially supported by Cooperative and Supporting Program for Researches and Educations in University sponsored by KEK. We proposed a torus knot type synchrotron radiation ring where the beam orbit is not closed with one turn but return to the starting position after multiple turns around the ring. This ring is capable of having many straight sections and it is advantageous for installation of insertion devices. We named this architecture AMATELAS. We are designing a new ring based on the shape of a (11, 3) torus knot for our future plan HiSOR-II. This ring has eleven 3.6-m-long straight sections though the ring diameter is as compact as 15 m. The achieved emittance is 17.4 nmrad with the lattice having bending magnets with combined function. This level of emittance is as low as the conventional 3rd generation light source. On the other hand, there is a potential problem caused by that the radius of the orbit and focusing force are not constant in the bending magnets. However, we confirmed that it does not make serious influence to the beam by calculating with dividing the bending into several sections. We will compare the parameters of this new ring with the conventional ring which we have designed as the future plan of our facility and evaluate performance as the compact synchrotron light source.

TUPPC015	Local Modification of Lattice of a Long Straight Section for Installing Small Gap In-vacuum Undulators at SPring-8	1188
	K. Soutome, T. Fujita, K. Fukami, K.K. Kaneki, C. Mitsuda, H. Ohkuma, M. Oishi, Y. Okayasu, S. Sasaki, J. Schimizu, Y. Shimosaki, M. Shoji, M. Takao, Y. Taniuchi, C. Zhang JASRI/SPring-8, Hyogo-ken, Japan M. Hasegawa, K. Kajimoto, T. Nakanishi SES, Hyogo-pref., Japan
	In the SPring-8 storage ring there are four magnet-free long straight sections (LSS) of about 30m. Recently we locally modified one of these sections by installing two quadrupole-triplets and divided it into three sub-sections. The vertical beta at the middle of each sub-section was lowered to 2.5m so that small gap in-vacuum undulators with a short period (min. gap: 5.2mm, period: 19mm) can be installed to build a high performance beamline for inelastic X-ray scattering. After modifying the lattice, however, the symmetry of the ring is lowered and, in general, it becomes difficult to keep sufficient dynamic aperture (DA) and momentum acceptance (MA). We solved this problem by combining the betatron phase matching, local chromaticity correction in LSS and cancellation of non-linear kicks due to sextupoles used for this correction. We could then recover DA and MA to almost the same level for the original one. The beam commissioning of the new lattice has successfully been finished, and from September 2011 it is used in user-operation. We will report our method of realizing a storage ring lattice having a very low symmetry and review the operation performance of the modified lattice.

Paper

Title

Page

Challenges of Quasiperiodic APPLE Undulators

705

J. Bahrdt
HZB, Berlin, Germany
S. Sasaki
HSRC, Higashi-Hiroshima, Japan

APPLE undulators have become workhorses in many synchrotron radiation facilities for the production of variably polarized light. In helical mode higher harmonics are not produced. In linear mode (horizontal, vertical, inclined) higher harmonics may contaminate the first harmonic and spoil the quality of experimental data. Planar undulators employing a quasiperiodic magnetic structure have been built and they are successfully operated at several places. The implementation of a quasiperiodic lattice in an APPLE undulator is more complicated since the device is operated in various modes of operation. The proposed APS-upgrade includes a quasiperiodic APPLE undulator which is intended to be operated in the range 2.4-27 keV. A detailed analysis of the magnetic and spectral performance of this device is presented.

MOPPP072

Performance of APPLE-II Type Quasi-Periodic Undulator at HiSOR

729

S. Sasaki, M. Arita, K. Goto, A. Miyamoto, T. Okuda
HSRC, Higashi-Hiroshima, Japan

A 1.8-m-long 78-mm-period quasi-periodic APLPE-II undulator was installed in the 700-MeV HiSOR storage ring of Hiroshima Synchrotron Radiation Center. At 23-mm nominal minimum gap, the fundamental photon energies are 3.1 eV, 6.5 eV, and 4.8 eV for horizontal linear, vertical linear, and circular polarization, respectively. The photon energies of observed fundamental and higher harmonic radiations are in good agreement with those of model calculations using measured undulator field and the HiSOR beam parameters. Also, observed flux thorough a slit and a grating monochromator was more than twice larger than that from previously installed 100-mm-period helical undulator for the whole range of radiation spectra. The feedforward COD correction was done to avoid the intensity fluctuation of photon beam in other BM beamlines due to the gap and phase motion of undulator. No fatal effect on the stored electron beam by installing the undulator was observed though a slight beam size change was observed at the minimum gap.

TUPPP014

HiSOR-II, Compact Light Source with a Torus-knot Type Accumulator Ring

1635

A. Miyamoto, S. Sasaki
HSRC, Higashi-Hiroshima, Japan

Funding: This work is partially supported by Cooperative and Supporting Program for Researches and Educations in University sponsored by KEK.
We proposed a torus knot type synchrotron radiation ring where the beam orbit is not closed with one turn but return to the starting position after multiple turns around the ring. This ring is capable of having many straight sections and it is advantageous for installation of insertion devices. We named this architecture AMATELAS. We are designing a new ring based on the shape of a (11, 3) torus knot for our future plan HiSOR-II. This ring has eleven 3.6-m-long straight sections though the ring diameter is as compact as 15 m. The achieved emittance is 17.4 nmrad with the lattice having bending magnets with combined function. This level of emittance is as low as the conventional 3rd generation light source. On the other hand, there is a potential problem caused by that the radius of the orbit and focusing force are not constant in the bending magnets. However, we confirmed that it does not make serious influence to the beam by calculating with dividing the bending into several sections. We will compare the parameters of this new ring with the conventional ring which we have designed as the future plan of our facility and evaluate performance as the compact synchrotron light source.

TUPPC015

Local Modification of Lattice of a Long Straight Section for Installing Small Gap In-vacuum Undulators at SPring-8

1188

K. Soutome, T. Fujita, K. Fukami, K.K. Kaneki, C. Mitsuda, H. Ohkuma, M. Oishi, Y. Okayasu, S. Sasaki, J. Schimizu, Y. Shimosaki, M. Shoji, M. Takao, Y. Taniuchi, C. Zhang
JASRI/SPring-8, Hyogo-ken, Japan
M. Hasegawa, K. Kajimoto, T. Nakanishi
SES, Hyogo-pref., Japan

In the SPring-8 storage ring there are four magnet-free long straight sections (LSS) of about 30m. Recently we locally modified one of these sections by installing two quadrupole-triplets and divided it into three sub-sections. The vertical beta at the middle of each sub-section was lowered to 2.5m so that small gap in-vacuum undulators with a short period (min. gap: 5.2mm, period: 19mm) can be installed to build a high performance beamline for inelastic X-ray scattering. After modifying the lattice, however, the symmetry of the ring is lowered and, in general, it becomes difficult to keep sufficient dynamic aperture (DA) and momentum acceptance (MA). We solved this problem by combining the betatron phase matching, local chromaticity correction in LSS and cancellation of non-linear kicks due to sextupoles used for this correction. We could then recover DA and MA to almost the same level for the original one. The beam commissioning of the new lattice has successfully been finished, and from September 2011 it is used in user-operation. We will report our method of realizing a storage ring lattice having a very low symmetry and review the operation performance of the modified lattice.