C. Boffo

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.

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.

COLDDIAG: A Cold Vacuum Chamber for Diagnostics

One of the still open issues for the development of superconducting insertion devices is the understanding of the heat load induced by the beam passage. With the aim of measuring the beam heat load to a cold bore and in order to gain a deeper understanding in the beam heat load mechanisms, a cold vacuum chamber for diagnostics is under construction. We plan to have access with the same set-up to a number of different diagnostics, so we are implementing: i) retarding field analysers to measure the electron flux, ii) temperature sensors to measure the total heat load, iii) pressure gauges, iv) and mass spectrometers to measure the gas content. The inner vacuum chamber will be removable in order to test different geometries and materials. COLDDIAG is built to fit in a short straight section at ANKA, but we are proposing its installation in different synchrotron light sources with different energies and beam characteristics. A first installation in DIAMOND is planned in June 2011. Here we describe the technical design report of this device and the planned measurements with beam.

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...

Overview of the superconducting undulator development program at ANKA

Superconducting undulators (SCUs) have the potential to reach higher brilliance and flux with respect to the state of the art permanent magnet insertion devices. ANKA is collaborating with the industrial partner Babcock Noell GmbH (BNG) to realize NbTi conduction cooled planar devices for low emittance light sources, and is developing the instrumentation to characterize the magnetic field properties and to measure the beam heat load to a cold bore needed for the cryogenic design of SCUs. We present here: the most recent results obtained within the ANKA-BNG collaboration, the progress achieved in the development of the instrumentation, and the in house studies on the application of high temperature superconducting (HTS) tape to the SCU technology.

Field quality of 1.5 m long conduction cooled superconducting undulator coils with 20 mm period length

The Institute for Beam Physics and Technology (IBPT) at the Karlsruhe Institute of Technology (KIT) and the industrial partner Babcock Noell GmbH (BNG) are collaborating since 2007 on the development of superconducting undulators both for ANKA and low emittance light sources. The first full length device with 15 mm period length has been successfully tested in the ANKA storage ring for one year. The next superconducting undulator has 20 mm period length (SCU20) and is also planned to be installed in the accelerator test facility and synchrotron light source ANKA. The SCU20 1.5 m long coils have been characterized in a conduction cooled horizontal test facility developed at KIT IBPT. Here we present the local magnetic field and field integral measurements, as well as their analysis including the expected photon spectrum.