IPAC2014 - List of Authors (Bahrdt, J.)

Paper	Title	Page
MOPRO057	Undulator Photon Beams with Orbital Angular Momentum	213
	J. Bahrdt, K. Holldack, P. Kuske, R. Müller, M. Scheer, P.O. Schmid HZB, Berlin, Germany
	Photons carrying orbital angular momentum (OAM) are present in the off-axis radiation of higher harmonics of helical undulators. Usually, the purity and visibility of OAM photons is blurred by electron beam emittance. However, high brightness OAM beams are expected in ultimate storage rings and FELs, and they may trigger a new class of experiments utilizing the variability of the topological charge, a 3rd degree of freedom besides wavelength and polarization. We report on the first detection of OAM photons in helical undulator radiation in the 3rd generation storage ring BESSY II. Measurements and simulations are compared and the impact of emittance and energy spread is discussed.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2014-MOPRO057
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TUPRO103	Novel Magnet Production Technique used for an Elliptically Polarizing Undulator	1286
	E.J. Wallén, K.I. Blomqvist MAX-lab, Lund, Sweden J. Bahrdt HZB, Berlin, Germany F.-J. Börgermann Vacuumschmelze GmbH & Co. KG, Hanau, Germany
	A common problem for elliptically polarizing undulators (EPUs) is that the magnetic forces give a mechanical deflection in the magnet holder construction when changing the undulator phase. Gluing horizontally and vertically magnetized blocks together can increase the mechanical stability of the magnet holders. The gluing process of pairs of magnetized magnet blocks is time-consuming, expensive and difficult to carry out with high positional precision. A novel magnet production technique has been developed where un-magnetized pairs of blocks are glued together before magnetization. The large number of parts, the time for assembly, and the cost of the EPU can be reduced with the novel magnet production technique. The novel magnet production method has been used for a 2.6 m long EPU of APPLE-II type, which has been built in-house at the MAX IV Laboratory. The frame for the EPU is made of cast iron in order to get a small mechanical deformation when changing phase in the inclined mode. The paper includes detailed descriptions of the novel magnet production technique, including measurements of the magnetization, and the new EPU.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2014-TUPRO103
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WEPRO029	Developing of Advanced Magnet Structures for Cryogenic in Vacuum Permanent Magnet Undulators	2004
	C. Kuhn, J. Bahrdt, A. Gaupp, M. Scheer, B. Schulz HZB, Berlin, Germany
	Cryogenic in vacuum permanent magnet undulators with periods less than 10 mm and correspondingly narrow gaps require tighter geometric and magnetic tolerances and complex pole designs from different materials to achieve the needed high field strengths. We use new mechanic designs and manufacturing technologies for magnet and pole assembly. We develop new precise and UHV-compatible joining methods which are different from the current approaches which are based on mechanical clamping or gluing. . We examine the mechanical and magnetic properties by performing tests and discuss the results.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2014-WEPRO029
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Paper

Title

Page

Undulator Photon Beams with Orbital Angular Momentum

213

J. Bahrdt, K. Holldack, P. Kuske, R. Müller, M. Scheer, P.O. Schmid
HZB, Berlin, Germany

Photons carrying orbital angular momentum (OAM) are present in the off-axis radiation of higher harmonics of helical undulators. Usually, the purity and visibility of OAM photons is blurred by electron beam emittance. However, high brightness OAM beams are expected in ultimate storage rings and FELs, and they may trigger a new class of experiments utilizing the variability of the topological charge, a 3rd degree of freedom besides wavelength and polarization. We report on the first detection of OAM photons in helical undulator radiation in the 3rd generation storage ring BESSY II. Measurements and simulations are compared and the impact of emittance and energy spread is discussed.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2014-MOPRO057

Export •

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

TUPRO103

Novel Magnet Production Technique used for an Elliptically Polarizing Undulator

1286

E.J. Wallén, K.I. Blomqvist
MAX-lab, Lund, Sweden
J. Bahrdt
HZB, Berlin, Germany
F.-J. Börgermann
Vacuumschmelze GmbH & Co. KG, Hanau, Germany

A common problem for elliptically polarizing undulators (EPUs) is that the magnetic forces give a mechanical deflection in the magnet holder construction when changing the undulator phase. Gluing horizontally and vertically magnetized blocks together can increase the mechanical stability of the magnet holders. The gluing process of pairs of magnetized magnet blocks is time-consuming, expensive and difficult to carry out with high positional precision. A novel magnet production technique has been developed where un-magnetized pairs of blocks are glued together before magnetization. The large number of parts, the time for assembly, and the cost of the EPU can be reduced with the novel magnet production technique. The novel magnet production method has been used for a 2.6 m long EPU of APPLE-II type, which has been built in-house at the MAX IV Laboratory. The frame for the EPU is made of cast iron in order to get a small mechanical deformation when changing phase in the inclined mode. The paper includes detailed descriptions of the novel magnet production technique, including measurements of the magnetization, and the new EPU.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2014-TUPRO103

Export •

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

WEPRO029

Developing of Advanced Magnet Structures for Cryogenic in Vacuum Permanent Magnet Undulators

2004

C. Kuhn, J. Bahrdt, A. Gaupp, M. Scheer, B. Schulz
HZB, Berlin, Germany

Cryogenic in vacuum permanent magnet undulators with periods less than 10 mm and correspondingly narrow gaps require tighter geometric and magnetic tolerances and complex pole designs from different materials to achieve the needed high field strengths. We use new mechanic designs and manufacturing technologies for magnet and pole assembly. We develop new precise and UHV-compatible joining methods which are different from the current approaches which are based on mechanical clamping or gluing. . We examine the mechanical and magnetic properties by performing tests and discuss the results.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2014-WEPRO029

Export •

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