Elena Mashkina

CASPER- A magnetic measurement facility for superconducting undulators

For a given gap and a given period length superconductive cold-bore undulators have a higher field strength compared to permanent magnet undulators. The measurement of the field and the field quality in the cold bore is demanding since the position of the Hall-probes have to be precise within a few microns over a distance of one to two meters. At the Forschungszentrum Karlsruhe two measuring facilities are under construction which allow to measure short mock-ups and undulators with a length of up to two meters. In this paper the two devices called CASPER (ChAracterization Setup for Phase Error Reduction) are described.

Magnetic Field Test Facility for Superconductive Undulator Coils

Superconducting undulators and wigglers are developed for synchrotron light sources, damping rings for linear colliders and polarized positron sources. In an undulator the emitted photons along the trajectory have to interfere. In order to do so the magnetic field in all periods has to be almost identical. The field strength over one or several hundred periods is not allowed to deviate by more than 1%. Translated into mechanical accuracy the position of the wire and the poles has to be more accurate than about 5 over 1 to 2 m. High quality measurement of the field is an essential requirement. In this paper we present two field measuring systems, one is under construction and another one is under design phase at the Forschungszentrum Karlsruhe.

Development of the Next Generation Superconductive Undulators for Synchrotron Light Sources

Superconducting insertion devices are very attractive for synchrotron light sources. For a given gap and period length, higher fields can be reached in respect to permanent magnet insertion devices thus permitting to reach higher photon fluxes. A new R&D program has been recently launched at ANKA aiming for the development of the next generation superconducting insertion devices for light sources. A cold bore superconducting undulator (14 mm period length, 100 full periods long) is installed in the ANKA storage ring since three years. This will be replaced by an improved version which shows a more efficient cooling system and a high precision design aiming for reduced field errors. Two additional devices are scheduled. One will allow to electrically switch the period length between 15 mm and 45 mm corresponding to an undulator and a wiggler mode, respectively. The other will be optimized for third generation light sources. It will be capable of tolerating higher beam heat loads up to 6 W while achieving very small field errors. The field error minimization will be obtained through the use of new shimming concepts which will correct inaccuracies due to manufacturing tolerances. This paper describes the technical concepts of the three projects.

Progress on the superconducting undulator for ANKA and on the instrumentation for R&D

Superconducting undulators show a larger magnetic field strength for the same gap and period length, as compared to permanent magnet devices, which allows to generate X‐ray beams of higher brilliance and with harder spectrum. The worldwide first short period length superconducting undulator is in operation since 2005 at the synchrotron light source ANKA in Karlsruhe [1]. To further drive the development in this field a research and development program is being carried out. In this contribution we report on the last progress of the construction of a 1.5 m long superconducting undulator with a period length of 15 mm, planned to be installed in ANKA beginning 2010 to be the light source of the new beamline NANO for high resolution X‐ray scattering. The key specifications of the system are an undulator parameter K higher than 2 (with a magnetic gap of 5 mm) and a phase error smaller than 3.5 degrees. Cryocoolers will keep the coils at 4.2 K for a beam heat load of 4 W. The ongoing R&D includes improvements in...

A New Superconducting Undulator for the ANKA Synchrotron Light Source

Superconducting insertion devices (IDs) are very attractive for synchrotron light sources since they allow increasing the flux and/or the photon energy with respect to permanent magnet IDs. Babcock Noell GmbH (BNG) is completing the fabrication of a 1.5 m long unit for ANKA at the Research Center in Karlsruhe (FZK). The period length of the device is 15 mm for a total of 100.5 full periods plus an additional matching period at each end. The key specifications of the system are: a K-value higher than 2, the capability of withstanding a 4 W beam heat load and a phase error smaller than 3.5 degrees. The magnet is in the final stages of the winding process and will be soon tested at CERN in liquid helium in vertical configuration. This paper describes the main features of the system, the results of the prototyping phase and details of manufacturing process.

Helium-Free Field Measurement System for Superconducting Undulator Coils

Superconducting undulators generate, for a given period length and a given gap, higher fields than permanent magnet undulators. Since in an undulator the photons add up coherently over the whole undulator length, even small magnetic field errors can disturb the superposition of photons and reduce the intensity of the generated photon beam. Therefore, as in any other undulator, the magnetic field has to be measured with high accuracy.

Test of an Electromagnetic Shimming Concept for Superconducting Undulators

Accurate magnetic field measurements are a prerequisite for the characterization and optimization of undulators. At the synchrotron light source ANKA there is an ongoing R&D program for superconducting insertion devices. Within this program a test stand for precise magnetic field measurements of superconductive coils was designed, built and installed at the Research Center Karlsruhe. Comprehensive magnetic measurements are performed to confirm the magnet design and to detect or correct field imperfections resulting from the manufacturing process. The magnetic field is measured along a fixed direction by Hall probes with a positioning precision of 3 mum. A NbTi undulator prototype with local correction coils was built to verify the performance of the superconductor and the shimming concept. In this contribution we describe the measuring test station and preliminary tests results including the efficiency of the shimming concept.

Measurements of the beam heat load in the cold bore superconductive undulator installed at ANKA

The beam heat load in the cold bore superconductive undulator installed at ANKA has been monitored for almost two years. The possible sources of the observed heat load as synchrotron radiation from upstream magnets, image currents, photo-excited electrons and ions will be discussed and compared with the experimental results.

Superconductive damping wigglers for the CLIC project

The CLIC damping ring requires wigglers with both high on-axis fields and short periods. The present design foresees a superconductive wiggler with a period length of 5 cm, a peak on-axis field of 2.5 T and a full aperture of 12 mm. In this paper we explore the performance improvements of the damping ring when these parameters are pushed to 2.7 T at a period length of 2 cm with the expense of a reduced aperture of 5 mm. A design for a prototype for testing the field quality of such a wiggler is presented in this paper and the possibility to test this wiggler with beam in the storage ring ANKA is described.