A. Grau

Training and Magnetic Field Measurements of the ANKA Superconducting Undulator

In this contribution we report the results of the training and of the local field measurements performed in a liquid helium bath of the ANKA superconducting undulator. The period length is 15 mm and the coils are 1.5 m long. The key specifications of the system are an undulator parameter K higher than 2 (for a magnetic gap of 5 mm) and a phase error smaller than 3.5 degrees. The superconducting undulator is planned to be installed in the ANKA storage ring by the beginning of 2011 to be the light source of the new beamline NANO for high resolution X-ray diffraction..

The New Conduction-Cooled Superconducting Undulator for ANKA

Babcock Noell GmbH (BNG) is completing the fabrication of a 1.5 m long superconducting insertion device for the Karlsruhe Institute of Technology (KIT). The unit is planned to be installed in the ANKA storage ring at the end of 2010 to become the light source of the new beamline NANO for high resolution X-ray diffraction. 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 for a magnetic gap of 5 mm, the capability of withstanding a 4 W beam heat load and a phase error smaller than 3.5 degrees. The superconducting coils have been qualified by means of a vertical test in liquid helium at CERN and are ready to be installed in the cryostat. This paper describes the main features of the system.

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.

Instrumentation for Local and Integral Field Measurements of Superconducting Undulator Coils

Accurate magnetic field measurements are a prerequisite for the characterization and optimization of undulators. The precision for measuring the magnetic properties of conventional, i.e., permanent magnet based insertion devices, has undergone tremendous improvements over the past 10 to 15 years initiating a new era in synchrotron light sources worldwide; a similar break through is now necessary in the field of superconducting insertion devices. In this contribution we describe the planned instrumentation needed to perform magnetic measurements of the local field, and field integrals, of up to 2 m length superconducting undulator coils while in a cold-in-vacuum (helium free) environment.

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 Superconducting Undulators at ANKA

In order to produce synchrotron radiation of the highest brilliance, third generation synchrotron sources make use of insertion devices (IDs). The state of the art available today for IDs is the permanent magnet technology with magnet blocks placed inside the vacuum (IVU) of the storage ring. Following an initial proposal at SPring-8 [1], the concept of Cryogenic Permanent Magnet Undulators (CPMU) is presently considered as a possible future evolution of in-vacuum undulators [2–5]. Superconducting undulators (SCUs) can reach, for the same gap and period length, even higher fields than CPMU devices, allowing increases in the spectral range and the brilliance. At ANKA we are running a research and development program to develop superconducting IDs. The proof of principle of SCU technology application in a storage ring has been demonstrated at ANKA with a device developed together with the company ACCEL Instr. GmbH and installed in the ANKA storage ring since March 2005 [6].

First Experimental Demonstration of Period Length Switching for Superconducting Insertion Devices

Superconducting insertion devices (IDs) are very attractive for synchrotron light sources since they offer the possibility to enhance the tuning range and functionality significantly by period length switching. Period length switching can be achieved by employing two or more individually powerable subsets of superconducting coils and reverse the current in a part of the windings. In this contribution we report the first experimental test of this principle demonstrated on a 70 mm NbTi mock-up coil with period tripling, allowing to switch between a 15 mm period length undulator and a 45 mm wiggler (SCUW 15/45).

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.

Test of Short Mockups for Optimization of Superconducting Undulator Coils

ANKA and Babcock Noell GmbH (BNG) collaborate to develop planar superconducting undulators for ANKA and low emittance light sources. We report here on the results of the training and magnetic field measurements on short mockup coils with 15- and 20-mm period length performed in the test facility CASPER I, that have qualified the wire and different winding schemes as promising to be applied to longer undulator coils.

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...