Limits...
Design and performance of the APPLE-Knot undulator.

Ji F, Chang R, Zhou Q, Zhang W, Ye M, Sasaki S, Qiao S - J Synchrotron Radiat (2015)

Bottom Line: Along with the development of accelerator technology, synchrotron emittance has continuously decreased.This results in increased brightness, but also causes a heavy heat load on beamline optics.Here, APPLE-Knot undulators which can generate photons with arbitrary polarization, with low on-axis heat load, are reported.

View Article: PubMed Central - HTML - PubMed

Affiliation: Department of Physics, State Key Laboratory of Surface Physics, and Laboratory of Advanced Materials, Fudan University, 2005 Songhu Road, Shanghai 200438, People's Republic of China.

ABSTRACT
Along with the development of accelerator technology, synchrotron emittance has continuously decreased. This results in increased brightness, but also causes a heavy heat load on beamline optics. Recently, optical surfaces with 0.1 nm micro-roughness and 0.05 µrad slope error (r.m.s.) have become commercially available and surface distortions due to heat load have become a key factor in determining beamline performance, and heat load has become a serious problem at modern synchrotron radiation facilities. Here, APPLE-Knot undulators which can generate photons with arbitrary polarization, with low on-axis heat load, are reported.

No MeSH data available.


Related in: MedlinePlus

Performance of combined magnets shown in Fig. 2(d) ▸ in horizontal (red), circular (green) and vertical (blue) modes. (a) Vertical (solid line) and horizontal (broken line) magnetic fields. (b) Fluxes (left axis, solid line) and linear or circular polarizations (right axis, broken line) at different photon energies. (c), (d), (e) Electron orbits and (f), (g), (h) electron velocities in horizontal, circular and vertical modes, respectively.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
getmorefigures.php?uid=PMC4489533&req=5

fig9: Performance of combined magnets shown in Fig. 2(d) ▸ in horizontal (red), circular (green) and vertical (blue) modes. (a) Vertical (solid line) and horizontal (broken line) magnetic fields. (b) Fluxes (left axis, solid line) and linear or circular polarizations (right axis, broken line) at different photon energies. (c), (d), (e) Electron orbits and (f), (g), (h) electron velocities in horizontal, circular and vertical modes, respectively.

Mentions: Another way to resolve the problem of the weak Knot fields is to superimpose the APPLE and Knot rows as shown in Fig. 2(e) ▸; that is, by vector addition of the magnetization and normalization of the final amplitude to the saturated value of the magnet material. Then the APPLE-Knot undulator recovers the standard APPLE four-row structure (Fig. 2d ▸) and the change is only the rotations of magnetic orientation. The ratio of the main (APPLE) and auxiliary (Knot) magnetic fields can be adjusted by the rotation angles, enabling the adjustment of the electron beam orbit to generate bright photons with acceptable heat load. A simple policy is that the electron beam should be deflected by more than half the divergence of the photons; then most of the heat load can be blocked by the white-light aperture in the beamline. The geometry parameters of magnets in Fig. 2(d) ▸ are a = b = 35 mm and e = 18.75 mm. The clearances are 3.5 mm and 2 mm between adjacent magnets along the x and z directions. The ratio of magnetization of APPLE and Knot magnets is chosen as 1.96 which corresponds to a typical rotation angle of 27°. The magnetic fields, electron beam orbits, photon fluxes and polarizations of the APPLE-Knot undulator with combined magnets in different modes are shown in Fig. 9 ▸. The horizontal, circular and vertical polarizations are 99%, 99% and 96% with corresponding heat loads of 13.2 W, 25.4 W and 233 W, respectively. Because of the stronger magnetic field, the period of combined magnets is shorter and more periods can be included in the straight section, resulting in higher flux and corresponding higher heat load compared with the structure of Fig. 2(c) ▸.


Design and performance of the APPLE-Knot undulator.

Ji F, Chang R, Zhou Q, Zhang W, Ye M, Sasaki S, Qiao S - J Synchrotron Radiat (2015)

Performance of combined magnets shown in Fig. 2(d) ▸ in horizontal (red), circular (green) and vertical (blue) modes. (a) Vertical (solid line) and horizontal (broken line) magnetic fields. (b) Fluxes (left axis, solid line) and linear or circular polarizations (right axis, broken line) at different photon energies. (c), (d), (e) Electron orbits and (f), (g), (h) electron velocities in horizontal, circular and vertical modes, respectively.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4489533&req=5

fig9: Performance of combined magnets shown in Fig. 2(d) ▸ in horizontal (red), circular (green) and vertical (blue) modes. (a) Vertical (solid line) and horizontal (broken line) magnetic fields. (b) Fluxes (left axis, solid line) and linear or circular polarizations (right axis, broken line) at different photon energies. (c), (d), (e) Electron orbits and (f), (g), (h) electron velocities in horizontal, circular and vertical modes, respectively.
Mentions: Another way to resolve the problem of the weak Knot fields is to superimpose the APPLE and Knot rows as shown in Fig. 2(e) ▸; that is, by vector addition of the magnetization and normalization of the final amplitude to the saturated value of the magnet material. Then the APPLE-Knot undulator recovers the standard APPLE four-row structure (Fig. 2d ▸) and the change is only the rotations of magnetic orientation. The ratio of the main (APPLE) and auxiliary (Knot) magnetic fields can be adjusted by the rotation angles, enabling the adjustment of the electron beam orbit to generate bright photons with acceptable heat load. A simple policy is that the electron beam should be deflected by more than half the divergence of the photons; then most of the heat load can be blocked by the white-light aperture in the beamline. The geometry parameters of magnets in Fig. 2(d) ▸ are a = b = 35 mm and e = 18.75 mm. The clearances are 3.5 mm and 2 mm between adjacent magnets along the x and z directions. The ratio of magnetization of APPLE and Knot magnets is chosen as 1.96 which corresponds to a typical rotation angle of 27°. The magnetic fields, electron beam orbits, photon fluxes and polarizations of the APPLE-Knot undulator with combined magnets in different modes are shown in Fig. 9 ▸. The horizontal, circular and vertical polarizations are 99%, 99% and 96% with corresponding heat loads of 13.2 W, 25.4 W and 233 W, respectively. Because of the stronger magnetic field, the period of combined magnets is shorter and more periods can be included in the straight section, resulting in higher flux and corresponding higher heat load compared with the structure of Fig. 2(c) ▸.

Bottom Line: Along with the development of accelerator technology, synchrotron emittance has continuously decreased.This results in increased brightness, but also causes a heavy heat load on beamline optics.Here, APPLE-Knot undulators which can generate photons with arbitrary polarization, with low on-axis heat load, are reported.

View Article: PubMed Central - HTML - PubMed

Affiliation: Department of Physics, State Key Laboratory of Surface Physics, and Laboratory of Advanced Materials, Fudan University, 2005 Songhu Road, Shanghai 200438, People's Republic of China.

ABSTRACT
Along with the development of accelerator technology, synchrotron emittance has continuously decreased. This results in increased brightness, but also causes a heavy heat load on beamline optics. Recently, optical surfaces with 0.1 nm micro-roughness and 0.05 µrad slope error (r.m.s.) have become commercially available and surface distortions due to heat load have become a key factor in determining beamline performance, and heat load has become a serious problem at modern synchrotron radiation facilities. Here, APPLE-Knot undulators which can generate photons with arbitrary polarization, with low on-axis heat load, are reported.

No MeSH data available.


Related in: MedlinePlus