The 2.5 GeV synchrotron facility ANKA, at Forschungs-zentrum Karlsruhe, Germany has three insertion devices which are in operation now. The SCU14 was the first superconducting undulator worldwide tested with beam [1]. The successor, SCU15 will be implemented in the ANKA ring in mid 2009. The paper describes the design and implementation of a modular control system structure, based on object oriented (oo) technologies for existing and future ANKAinsertion devices (IDs) with permanent- or superconducting magnets. It gives the description of a hardware solution, based on Cosylabs MICROIOC MCS8-PMAC2 interface [2] for undulator motion control of gaps and scrapers, main power supply, corrector power supplies, temperature control and Interlocks (ILs). Last but not least the integration of the housekeeping functions, cooling, vacuum control and Interlocks to SCADA-PVSS II and the communication with ACS are described.

The 2.5 GeV synchrotron facility ANKA, at Forschungs-zentrum Karlsruhe, Germany has three insertion devices which are in operation now. The SCU14 was the first superconducting undulator worldwide tested with beam (1). The successor, SCU15 will be implemented in the ANKA ring in mid 2009. The paper describes the design and implementation of a modular control system structure, based on object ori- ented (oo) technologies for existing and future ANKA- insertion devices (IDs) with permanent- or supercon- ducting magnets. It gives the description of a hardware solution, based on Cosylabs MICROIOC MCS8-PMAC2 interface (2) for undulator motion control of gaps and scrapers, main power supply, corrector power supplies, temperature control and Interlocks (ILs). Last but not least the integration of the housekeeping functions, cooling, vacuum control and Interlocks to SCADA-PVSS II and the communication with ACS are described.

A synchrotron radiation source emits coherent infrared (IR) radiation when the electron bunch length is comparable to the wavelength of the emitted radiation (see for example [1, 2]). To generate coherent radiation in the far IR (THz) region, a ’low alpha mode’ has been devised at the ANKA storage ring operating at 1.3 GeV. The corresponding lattice has a significantly reduced momentum compaction factor. The spectral dependence of the emitted radiation is recorded at the ANKA-IR beam line, where the synchrotron light is produced in the fringe field of a bending magnet [3]. This edge radiation has the advantage of being more collimated than constant field radiation. This allows the observation of frequencies down to 1 cm-1through a modest vertical aperture, which would not be possible with classical constant field emission due to the increasing beam divergence with decreasing frequency. The onset of coherent emission is found at a synchrotron frequency of about 10 kHz. At 5 kHz, an intensity enhancement of up to 5 orders of magnitude, with respect to the incoherent emission, is observed in the spectral range between 1 and 65 cm-1.

ANKA is a 2.5 GeV synchrotron radiation facility under construction at Forschungszentrum Karlsruhe. ANKA is based on a 2.5 GeV electron storage ring injected from a 500 MeV booster synchrotron and a 50 MeV racetrack microtron. Nominal circulating electron current will be 400 mA. The facility is scheduled to become operational in fall 2000. ANKA will deliver photons predominantly in the hard X-ray range but it will also feature both XUV and infrared beamlines. So far, all beamlines will use bending magnets as sources, while provision is made to install appropriate insertion devices later on. ANKA has a novel mission which is characterised by giving preference to providing service to customers while maintaining a significant fraction of research work. ANKA will offer full service in X-ray lithography, mainly far micro- and nanofabrication, and in analysing and investigating non-destructively various structural, mechanical, chemical, electronic, magnetic, and molecular properties of samples and components.

Low-energy magnetic excitations in Nd2-xCexCuO4 with 0 less than or equal to x less than or equal to 0.2 have been investigated by measurements of the specific heat. For all Ce-doped samples (x greater than or equal to 0.05), a linear term gamma T was found at very low temperatures (T less than or similar to 0.5 K), with 0.3 J/K-2 less than or similar to gamma less than or similar to 0.6 J/K-2 per mole Nd for 0.05 less than or equal to x < 0.14, and 3 J/K-2 less than or similar to gamma less than or similar to 4 J/K-2 per mole Nd for higher Ce concentrations. In overdoped Nd1.8Ce0.2CuO4, gamma is rapidly suppressed in magnetic fields exceeding 1.5 T. The temperature dependence of the electrical resistance parallel to the CuO2 planes corresponds to that of two-dimensional metals. The magnetoresistance of Nd1.8Ce0.2CuO4 Single crystals and c-axis-oriented thin films in magnetic fields parallel to the CuO2 planes is monotonously negative at temperatures above 1 K. Below about 500 mK, the magnetoresistance is positive in small fields, it goes through a maximum near 2 T, and it is negative for B > 2 T. These features are similar to those observed in heavy-fermion systems. In contrast, in Pr1.8Ce0.2CuO4, with nonmagnetic Pr, the magnetoresistance is negative at all temperatures of our measurements down to 20 mK. This proves unambiguously that interactions between conduction electrons and Nd moments give rise to the low-temperature maximum of the magnetoresistance. Furthermore, a comparison of the magnetoresistance with the modification of the specific heat by magnetic fields supports the interpretation of the large linear term as resulting from the interaction between Nd moments and conduction electrons.

The relaxation of the irreversible magnetization has been measured by a Faraday magnetometer for the weakly anisotropic polycrystalline Tl0.5Pb0.5Sr2Ca2Cu3O9 (Tl-1223) and a highly anisotropic Tl2Ba2Ca2 Cu3O10 (Tl-2223) single crystal. From these data, the effective activation energy, U eff(j)=U l(j c /j)μ, is determined by the method of Maley. A comparison of the irreversibility data at 77 K for different high-temperature superconductors (HTSC) indicates that the irreversibility field is quickly decreasing with increasing distance between the superconducting CuO2-layers. In agreement with this tendency, U eff is higher for the one-intermediatelayer compound Tl-1223 than for the highly anisotropic two-intermediate-layer Tl-2223 compound. The exponent μ≡d log(U eff)/d log(j) saturates for Tl-1223 at a value of μ≈1.4 near j c and decreases with decreasing current down to 0.3. On the other hand μ increases for Tl-2223 with increasing current from 0.1 up to 2.5 and shows no tendency to saturate. A comparison with data for Y-123 and Bi-2212 taken from literature, indicates that the flux creep in Tl-1223 is 3-dimensional like in Y-123. Therefore it can be explained by the 3D collective creep model for not too small currents. For Tl-2223, 2-dimensional behaviour is observed.

As a first step in the investigation of Tl-1223 high-temperature-superconductors (HTSC) and the further development of tape conductors, the critical currents of polycrystalline Tb0.5Pb0.5Sr2Ca2Cu3O9 (Tl-Sr-1223) bulk samples were investigated with a Faraday magnetometer up to B = 12 T and compared to Tl2Ba2Ca2Cu3O10 (Tl-2223) single crystals. The magnetic hysteresis of Tl-Sr-1223 yields high intragrain critical current densities of up to 10(6) A/cm(2) at low temperatures (4.2 K, 1 T) and 10(4) A/cm2 at 77 K, 1 T. The effective activation energy, Ueff((j)= Ui (j(c)/j)(mu), as determined by the method of Maley, is higher for the one-intermediate-layer compound Tl-1223 than for the highly anisotropic two- intermediate-layer Tl 2223 compound. A comparison with data far Y-123 and and Bi-2212 from literature indicates, that flux creep in Tl-1223 is 3-dimensional like in Y-123 and might be explained by the 3D collective creep model for not too small currents. For Tl-2223, a 2-dimensional behaviour is expected. The microstructure and critical currents of short tapes of (Tl/Pb/Bi)(1)(Sr/Ba)(2)(Ca/Tl)(2)Cu3O9, prepared by the powder-in-tube technique, were investigated by TEM, SEM and resistive measurements. The tapes show no pronounced texture and therefore, only relatively small intergrain critical currents of 9000 A/cm(2) (77 K, 0 T), whereas the intragrain current is about ldl A/cm(2). The intergrain current density of the Tl-1223 tape is inhomogeneously distributed in the flat-rolled HTSC core. It is higher at the edge than in the middle of the core. The TEM observations reveal no impurities in the grain boundaries and a dislocation density of the order of 10(10) cm(-2).

Due to an eddy current-free sample holder of a high mass density, it is possible to investigate the magnetic relaxation of high temperature superconductors at early times with a Faraday magnetometer. The experiments can be performed beginning after to≊1 s with a resolution of 10−5 in the susceptibility.

To avoid weak-link behavior caused by grain boundaries small crystallites of YBa2Cu3O7-delta were mechanically separated from approximately 1 cm3 Bridgman-melt-textured blocks. Using the Bean critical-state model, j(c) values at 4 K and 5 T (70 K and 2 T) as high as approximately 2 X 10(6) A/cm2 (approximately 4 X 10(4) A/cm2) were estimated from the width of the magnetization hysteresis. Microstructural investigations of the crystallites reveal the existence of dislocations, finely distributed inclusions, stacking faults, twin boundaries, elementary growth steps, and oxygen-deficient regions. The defects are thought to have a strong influence on the pinning behavior and the shape of the magnetization curve.