Canted-cosine-theta magnet (CCT)-A concept for high field accelerator magnets

Canted-Cosine-Theta (CCT) magnet is an accelerator magnet that superposes fields of nested and tilted solenoids that are oppositely canted. The current distribution of any canted layer generates a pure harmonic field as well as a solenoid field that can be cancelled with a similar but oppositely canted layer. The concept places windings within mandrel's ribs and spars that simultaneously intercept and guide Lorentz forces of each turn to prevent stress accumulation. With respect to other designs, the need for pre-stress in this concept is reduced by an order of magnitude making it highly compatible with the use of strain sensitive superconductors such as Nb3Sn or HTS. Intercepting large Lorentz forces is of particular interest in magnets with large bores and high field accelerator magnets like the one foreseen in the future high energy upgrade of the LHC. This paper describes the CCT concept and reports on the construction of CCT1 a "proof of principle" dipole

Development and analysis of HTS-undulator components for FEL applications

A high-performance superconducting undulator concept, incorporating stacked YBa2Cu3O7δ (YBCO) tapes operating at 4.2 K, is currently under investigation at LBNL as one of many technology options for future FEL applications. The concept is particularly promising for narrow-gap, short period (<10 mm) regimes, where traditional superconducting and permanent magnet technologies are less-suited. The current path is dictated by etching the YBCO layer using lithography techniques, resulting in a high degree of uniformity from tape to tape as well as a straightforward and highly cost-effective means of production. We describe the approaches being pursued for the tape preparation and the conceptual design of a device. We also provide an initial analysis of the impact of fabrication tolerances in terms of field errors for FEL application. © 2011 IEEE

Magnetic field correction concepts for superconducting undulators

The ability to correct magnetic field errors in a superconducting undulator is critical for the successful application of these devices in future and existing light sources. These field errors, which can emanate from sources such as machining and coil winding imperfections, can lead to reduced light source performance by introducing errors in both the electron trajectory and the relative phase relationship between the oscillating electrons and the emitted photons. In this work, correction schemes are presented, which use a single power supply along with a superconducting switch network to define the path for the current during undulator tuning. The basic switching concept was previously designed and successfully tested at Lawrence Berkeley National Laboratory; the approach presented here is a significant advancement in generalizing and scaling that core concept. A new fabrication method is presented here, which uses lithographic methods to produce current paths and switch heaters on a superconducting film. The effect of an example corrector current path design on the magnetic field is investigated using the Finite Element Method, and the results at various undulator and corrector energization levels are presented. Experimental results from the heater switch concept are also presented. © 2002-2011 IEEE

Magnetic field correction concepts for superconducting undulators

The ability to correct magnetic field errors in a superconducting undulator is critical for the successful application of these devices in future and existing light sources. These field errors, which can emanate from sources such as machining and coil winding imperfections, can lead to reduced light source performance by introducing errors in both the electron trajectory and the relative phase relationship between the oscillating electrons and the emitted photons. In this work, correction schemes are presented, which use a single power supply along with a superconducting switch network to define the path for the current during undulator tuning. The basic switching concept was previously designed and successfully tested at Lawrence Berkeley National Laboratory; the approach presented here is a significant advancement in generalizing and scaling that core concept. A new fabrication method is presented here, which uses lithographic methods to produce current paths and switch heaters on a superconducting film. The effect of an example corrector current path design on the magnetic field is investigated using the Finite Element Method, and the results at various undulator and corrector energization levels are presented. Experimental results from the heater switch concept are also presented. © 2002-2011 IEEE

Design, fabrication, and test results of undulators using Nb 3Sn superconductor

An R&D effort is underway at Lawrence Berkeley National Laboratory (LBNL) to develop the technology of Nb 3Sn superconducting undulators (SCUs). Issues relating to the selection of the appropriate conductor are discussed. The design and fabrication of SCUs using Nb 3Sn is presented. Two prototype devices have been designed and fabricated at LBNL. The first device concentrated on basic fabrication issues and on magnet protection, a key concern due to extremely high copper current densities during a quench. Test on the first prototype demonstrated that such devices can be passively protected in a scalable manner. The second device incorporated design improvements as well as trim coils that are designed to serve as the basic element of a future active phase error correction approach. Preliminary tests on the second device are presented. The trim coils were successfully tested at a variety of field levels. Two quench runs were performed, both occurring at ∼70% of short-sample J c. Stability issues associated with flux-jumps and possible epoxy cracking are discussed. © 2005 IEEE

Canted-cosine-theta magnet (CCT)-A concept for high field accelerator magnets

Canted-Cosine-Theta (CCT) magnet is an accelerator magnet that superposes fields of nested and tilted solenoids that are oppositely canted. The current distribution of any canted layer generates a pure harmonic field as well as a solenoid field that can be cancelled with a similar but oppositely canted layer. The concept places windings within mandrel's ribs and spars that simultaneously intercept and guide Lorentz forces of each turn to prevent stress accumulation. With respect to other designs, the need for pre-stress in this concept is reduced by an order of magnitude making it highly compatible with the use of strain sensitive superconductors such as Nb3Sn or HTS. Intercepting large Lorentz forces is of particular interest in magnets with large bores and high field accelerator magnets like the one foreseen in the future high energy upgrade of the LHC. This paper describes the CCT concept and reports on the construction of CCT1 a "proof of principle" dipole