IPAC2011 - List of Authors (Wuestefeld, G.)

Paper

Title

Page

Simultaneous Long and Short Bunch Operation in an Electron Storage Ring - a Hybrid Mode based on Nonlinear Momentum Compaction

945

M. Ries, J. Feikes, A. Jankowiak, P.O. Schmid, G. Wüstefeld
HZB, Berlin, Germany

The generation of short pulses in electron storage rings is driven by different user groups like time resolved x-ray spectroscopy users or users of coherent synchrotron radiation. The required optics and operation conditions to generate this short bunches are worsening the experimental conditions, e.g. strongly reducing the average photon flux, for the regular user. Therefore short bunch operation is usually limited to dedicated user shifts. By controlling higher orders of the momentum compaction factor by higher multipoles it is possible to introduce a hybrid mode and simultaneously supplying long and short bunches*. The Metrology Light Source (MLS) has the means to control these higher orders**, therefore it is an ideal machine to investiate the feasibility of such a hybrid mode. Tracking results and first measurements will be shown.
* D. Robin et al., Proc. of EPAC08, p. 2100-2102, Genoa, Italy (2008).
** J. Feikes et al., Phys. Rev. ST Accel. Beams 14, 030705 (2011).

Slides TUOAB02 [7.817 MB]

TUPC072

Accurate Electron Beam Size Measurement at the Metrology Light Source

1165

R. Klein, G. Brandt, R. Thornagel
PTB, Berlin, Germany
J. Feikes, M. Ries, G. Wüstefeld
HZB, Berlin, Germany

For the operation of the Metrology Light Source (MLS)*, the dedicated electron storage ring of the Physikalisch-Technische Bundesanstalt (PTB), as the national primary radiation source standard from the near infrared to the vacuum ultraviolet spectral region, all storage ring parameters which are relevant for the calculation of the radiant intensity by the Schwinger equation have to be known absolutely with small uncertainties. For the measurement of the effective vertical electron beam size a Bragg polarimeter, operating at a photon energy of 1103 eV, has been designed and put into operation. This system also serves as a detection system for the image of the electron beam through a set of narrow slits. The results obtained with the new device are compared to those measured by an optical beam imaging system**.
* R. Klein et al., Phys. Rev. ST-AB 11, 110701 (2008).
** C. Koschitzki et al., Proc. IPAC10, 894-896 (2010).

THPC012

Mitigating the Pertubations Caused by U 180 at the Metrology Light Source

2930

P.O. Schmid, D.B. Engel, J. Feikes, M. Ries, G. Wüstefeld
HZB, Berlin, Germany

The Metrology Light Source is equipped with an electromagnetic undulator with a period length of 180 mm. User requests demand operation of this undulator in a wide energy range from 100 MeV through 629 MeV for user and dedicated low alpha modes. Mitigating the pertubations caused by the undulator to an acceptable level for all user requests, requires each quadrupole in the lattice to be powered individually. To what extend this recently implemented capability allows the restoration of the main properties of the machine optics for various settings of the undulator is presented in this document.

THPC013

THz Studies at a Dedicated Beamline at the MLS

2933

R. Müller, A. Hoehl, A. Serdyukov, G. Ulm
PTB, Berlin, Germany
J. Feikes, M. Ries, G. Wüstefeld
HZB, Berlin, Germany

The Physikalisch-Technische Bundesanstalt (PTB), the German national metrology institute is operating the low-energy electron storage ring Metrology Light Source (MLS) in Berlin-Adlershof in close cooperation with the Helmholtz-Zentrum Berlin. The MLS is designed and prepared for a special machine optics mode (low-alpha operation mode) based on a sextupole and octupole correction scheme, for the production of coherent synchrotron radiation in the THz region*. At the MLS two bending magnet beamlines dedicated to the use of IR and THz synchrotron radiation are in operation: the MLS-IR beamline optimized for the NIR to FIR, and a dedicated THz beamline optimized for the FIR/THz spectral range**. Low-alpha operation optic modes for different ring energies, 250 MeV, 350 MeV, 450 MeV and 630 MeV are available. We compare the THz spectra taken in the different low-alpha modes and discuss the results.
* J. Feikes et al., Phys. Rev. ST Accel. Beams 14, 030705 (2011).
** R. Müller et al., J. Infrared Milli Terahz Waves, in press (2011), DOI: 10.10⁰⁷/s10762-011-9785-6.

THPC014

Simultaneous Long and Short Electron Bunches in the BESSY II Storage Ring

2936

G. Wüstefeld, A. Jankowiak, J. Knobloch, M. Ries
HZB, Berlin, Germany

A scheme is discussed, where short and long bunches can be stored simultaneously in the BESSY II storage ring. With recent developments in sc-rf cavity technology it becomes possible, to install high gradient cavities in electron storage rings. With an appropriate choice of these cavities stable fixed points with different rf-voltage gradients are available, leading to different zero current bunch lengths. For BESSY II, we discuss the simultaneously storage of bunches with rms-lengths of 2 ps and 15 ps at high beam intensities. Additionally, in a low alpha optics sub-ps and ps-bunches are possible and a double bucket optics can be set up to store the two types of beams simultaneously on different orbits. Ultra-short and long bunches can be supplied to the users, separated by slightly different orbits.

THPC010

Recent Developments at the Metrology Light Source

2927

J. Feikes, T. Birke, O. Dressler, D.B. Engel, F. Falkenstern, B. Franksen, A. Heugel, H.-G. Hoberg, F. Hoffmann, J. Kuszynski, J. Rahn, M. Ries, P.O. Schmid, T. Schneegans, D. Schüler, G. Wüstefeld
HZB, Berlin, Germany
K.B. Bürkmann-Gehrlein, V. Dürr, H.G. Glass, G. Schindhelm
BESSY GmbH, Berlin, Germany
R. Klein
PTB, Berlin, Germany

The Physikalisch-Technische Bundesanstalt (PTB), the German national metrology institute, owns the electron storage ring Metrology Light Source (MLS) which was built and is operated by the Helmholtz-Zentrum Berlin [1, 2]. The MLS has been in regular user operation since April 2008 and supports synchrotron-radiation-based metrology and technological developments in the IR, UV, VUV and EUV spectral range. Here we report on recent progress to develop the MLS into a reliable, flexible and stable user facility.

THPC154

Shimming of the Dynamic Field Integrals of the BESSY II U125 Hybrid Undulator

3248

J. Bahrdt, W. Frentrup, A. Gaupp, M. Scheer, I. Schneider, G. Wüstefeld
HZB, Berlin, Germany

Within a continuous program the BESSY II undulators are prepared for Topping-Up operation. The BESSY II U125 planar hybrid undulator has a period length of 125 mm and a pole width of only 60 mm. The horizontal defocusing of the 1.7 GeV e-beam may result in a significant reduction of the horizontal dynamic aperture, reducing the injection efficiency when injecting into the closed gap. The dynamic field integrals are derived from a 2D-Fourier decomposition of the 3D-field. An analytic description of the dynamic multipoles based on the Fourier coefficients is presented. Magic fingers have been installed in order to minimize the dynamic field integrals and to enlarge the good field region of the device.

THPC155

Modification of the BESSY II Optic for the Implementation of a Small Gap Undulator

3251

J. Bahrdt, K.B. Bürkmann-Gehrlein, V. Dürr, W. Frentrup, A. Gaupp, A. Jankowiak, P. Kuske, J. Rahn, M. Scheer, P.O. Schmid, G. Wüstefeld
HZB, Berlin, Germany

At BESSY there is an increasing demand for photons in the range from 60 eV to 8 keV available at the same experimental station. The photons will be produced by a combination of two adjacent undulators, one of them will be a small period cryogenic undulator. Several optics schemes for the 1.7 GeV BESSY II storage ring are discussed to install the undulators. Two types of straight sections exist. A high beta straight with betax_min=15 m and betay_min=4.5 m and a low beta straight with betax_min=betay_min=1 m. We discuss the present plan, which clearly favours a small detuning of an existing low beta straight to shift the low beta waist to the centre of the low gap undulator, with only minor impact to the machine.

Paper	Title	Page
TUOAB02	Simultaneous Long and Short Bunch Operation in an Electron Storage Ring - a Hybrid Mode based on Nonlinear Momentum Compaction	945
	M. Ries, J. Feikes, A. Jankowiak, P.O. Schmid, G. Wüstefeld HZB, Berlin, Germany
	The generation of short pulses in electron storage rings is driven by different user groups like time resolved x-ray spectroscopy users or users of coherent synchrotron radiation. The required optics and operation conditions to generate this short bunches are worsening the experimental conditions, e.g. strongly reducing the average photon flux, for the regular user. Therefore short bunch operation is usually limited to dedicated user shifts. By controlling higher orders of the momentum compaction factor by higher multipoles it is possible to introduce a hybrid mode and simultaneously supplying long and short bunches. The Metrology Light Source (MLS) has the means to control these higher orders, therefore it is an ideal machine to investiate the feasibility of such a hybrid mode. Tracking results and first measurements will be shown. D. Robin et al., Proc. of EPAC08, p. 2100-2102, Genoa, Italy (2008). ** J. Feikes et al., Phys. Rev. ST Accel. Beams 14, 030705 (2011).
	Slides TUOAB02 [7.817 MB]

TUPC072	Accurate Electron Beam Size Measurement at the Metrology Light Source	1165
	R. Klein, G. Brandt, R. Thornagel PTB, Berlin, Germany J. Feikes, M. Ries, G. Wüstefeld HZB, Berlin, Germany
	For the operation of the Metrology Light Source (MLS), the dedicated electron storage ring of the Physikalisch-Technische Bundesanstalt (PTB), as the national primary radiation source standard from the near infrared to the vacuum ultraviolet spectral region, all storage ring parameters which are relevant for the calculation of the radiant intensity by the Schwinger equation have to be known absolutely with small uncertainties. For the measurement of the effective vertical electron beam size a Bragg polarimeter, operating at a photon energy of 1103 eV, has been designed and put into operation. This system also serves as a detection system for the image of the electron beam through a set of narrow slits. The results obtained with the new device are compared to those measured by an optical beam imaging system. R. Klein et al., Phys. Rev. ST-AB 11, 110701 (2008). ** C. Koschitzki et al., Proc. IPAC10, 894-896 (2010).

THPC012	Mitigating the Pertubations Caused by U 180 at the Metrology Light Source	2930
	P.O. Schmid, D.B. Engel, J. Feikes, M. Ries, G. Wüstefeld HZB, Berlin, Germany
	The Metrology Light Source is equipped with an electromagnetic undulator with a period length of 180 mm. User requests demand operation of this undulator in a wide energy range from 100 MeV through 629 MeV for user and dedicated low alpha modes. Mitigating the pertubations caused by the undulator to an acceptable level for all user requests, requires each quadrupole in the lattice to be powered individually. To what extend this recently implemented capability allows the restoration of the main properties of the machine optics for various settings of the undulator is presented in this document.

THPC013	THz Studies at a Dedicated Beamline at the MLS	2933
	R. Müller, A. Hoehl, A. Serdyukov, G. Ulm PTB, Berlin, Germany J. Feikes, M. Ries, G. Wüstefeld HZB, Berlin, Germany
	The Physikalisch-Technische Bundesanstalt (PTB), the German national metrology institute is operating the low-energy electron storage ring Metrology Light Source (MLS) in Berlin-Adlershof in close cooperation with the Helmholtz-Zentrum Berlin. The MLS is designed and prepared for a special machine optics mode (low-alpha operation mode) based on a sextupole and octupole correction scheme, for the production of coherent synchrotron radiation in the THz region. At the MLS two bending magnet beamlines dedicated to the use of IR and THz synchrotron radiation are in operation: the MLS-IR beamline optimized for the NIR to FIR, and a dedicated THz beamline optimized for the FIR/THz spectral range. Low-alpha operation optic modes for different ring energies, 250 MeV, 350 MeV, 450 MeV and 630 MeV are available. We compare the THz spectra taken in the different low-alpha modes and discuss the results. J. Feikes et al., Phys. Rev. ST Accel. Beams 14, 030705 (2011). ** R. Müller et al., J. Infrared Milli Terahz Waves, in press (2011), DOI: 10.10⁰⁷/s10762-011-9785-6.

THPC014	Simultaneous Long and Short Electron Bunches in the BESSY II Storage Ring	2936
	G. Wüstefeld, A. Jankowiak, J. Knobloch, M. Ries HZB, Berlin, Germany
	A scheme is discussed, where short and long bunches can be stored simultaneously in the BESSY II storage ring. With recent developments in sc-rf cavity technology it becomes possible, to install high gradient cavities in electron storage rings. With an appropriate choice of these cavities stable fixed points with different rf-voltage gradients are available, leading to different zero current bunch lengths. For BESSY II, we discuss the simultaneously storage of bunches with rms-lengths of 2 ps and 15 ps at high beam intensities. Additionally, in a low alpha optics sub-ps and ps-bunches are possible and a double bucket optics can be set up to store the two types of beams simultaneously on different orbits. Ultra-short and long bunches can be supplied to the users, separated by slightly different orbits.

THPC010	Recent Developments at the Metrology Light Source	2927
	J. Feikes, T. Birke, O. Dressler, D.B. Engel, F. Falkenstern, B. Franksen, A. Heugel, H.-G. Hoberg, F. Hoffmann, J. Kuszynski, J. Rahn, M. Ries, P.O. Schmid, T. Schneegans, D. Schüler, G. Wüstefeld HZB, Berlin, Germany K.B. Bürkmann-Gehrlein, V. Dürr, H.G. Glass, G. Schindhelm BESSY GmbH, Berlin, Germany R. Klein PTB, Berlin, Germany
	The Physikalisch-Technische Bundesanstalt (PTB), the German national metrology institute, owns the electron storage ring Metrology Light Source (MLS) which was built and is operated by the Helmholtz-Zentrum Berlin [1, 2]. The MLS has been in regular user operation since April 2008 and supports synchrotron-radiation-based metrology and technological developments in the IR, UV, VUV and EUV spectral range. Here we report on recent progress to develop the MLS into a reliable, flexible and stable user facility.

THPC154	Shimming of the Dynamic Field Integrals of the BESSY II U125 Hybrid Undulator	3248
	J. Bahrdt, W. Frentrup, A. Gaupp, M. Scheer, I. Schneider, G. Wüstefeld HZB, Berlin, Germany
	Within a continuous program the BESSY II undulators are prepared for Topping-Up operation. The BESSY II U125 planar hybrid undulator has a period length of 125 mm and a pole width of only 60 mm. The horizontal defocusing of the 1.7 GeV e-beam may result in a significant reduction of the horizontal dynamic aperture, reducing the injection efficiency when injecting into the closed gap. The dynamic field integrals are derived from a 2D-Fourier decomposition of the 3D-field. An analytic description of the dynamic multipoles based on the Fourier coefficients is presented. Magic fingers have been installed in order to minimize the dynamic field integrals and to enlarge the good field region of the device.

THPC155	Modification of the BESSY II Optic for the Implementation of a Small Gap Undulator	3251
	J. Bahrdt, K.B. Bürkmann-Gehrlein, V. Dürr, W. Frentrup, A. Gaupp, A. Jankowiak, P. Kuske, J. Rahn, M. Scheer, P.O. Schmid, G. Wüstefeld HZB, Berlin, Germany
	At BESSY there is an increasing demand for photons in the range from 60 eV to 8 keV available at the same experimental station. The photons will be produced by a combination of two adjacent undulators, one of them will be a small period cryogenic undulator. Several optics schemes for the 1.7 GeV BESSY II storage ring are discussed to install the undulators. Two types of straight sections exist. A high beta straight with betax_min=15 m and betay_min=4.5 m and a low beta straight with betax_min=betay_min=1 m. We discuss the present plan, which clearly favours a small detuning of an existing low beta straight to shift the low beta waist to the centre of the low gap undulator, with only minor impact to the machine.