The Beam Line VI REC-Steel Hybrid Wiggler for SSRL

Abstract

A wiqgler magnet with 27 period?, each 7 cat long which reaches 1.21 T at a 1.2 cm gap and 1.64 T at 0.8 cm gap has been designed and is in fabrication. Installation in SPEAR Is scheduled for mid 1983. This new wiggler will be the radiation source for a new high intensity synchrotron radiation beam line at SSR" The magnet utilizes rare-earth cobalt (REC) abt.er1al and steel 1n a hybrid configuration to achieve simul taneously a high magnetic field with a short period. The magnet Is external to a thin walled variable gap stainless steel vacuum chamber which is opened tc pro vide beam aperture of 1.8 cm gap at Injection and then closed to a smaller aperture (< 1.0 cm). Five indepen dent drive systems are provided to adjust the magnet and chamber gaps and alignment. Magnetic design, construction details and magnetic measurements are presented.

Early Work with Synchrotron Radiation at Stanford

“…Insertion-device development at the SSRL continued with the design and construction, in collaboration with the LBNL and EXXON, of the 54-pole hybrid wiggler with variablegap vacuum chamber (Hoyer et al, 1983) and subsequent wigglers and undulators, including the multiple undulator system that could select from four undulators with different periods on the same beamline (Bachrach et aL, 1985), the adjustable phase undulator (Carr, 1991) and the elliptical polarizing undulator (Lidia & Carr, 1994).…”

Analysis of field errors in existing undulators

“…Magnetic field data for three different insertion devices were analyzed, the LBL-SSRL-EXXON beamline VI wiggler (BL VI) [4] the NSLS TOK undulator (TOK) [5] and the LLNL-LBL-SSRL beamline X wiggler (BL X) [6] . The BL VI magnet is a samarium-cobalt/vanadium Permendur hybrid wiggler, the first such device built, installed in 1983.…”

“…The essentials of the process of producing this figure are as follows: multiply the raw data of Fig. 5 by a window function to suppress side lobe artifacts in the transform [9] , interpolate possibly nonuniformly spaced data onto a uniform mesh, pad with zeros, Fourier transform using the FFT algorithm, normalize the magnitude of the complex Fourier transform to unit 4 first harmonic height, and take the base ten logarithm. The windowing operation also tends to reduce the weight of the non-periodic fields in the end region.…”

Calculation of magnetic error fields in hybrid insertion devices

“…In this paper we use the theory [2,3,4] developed by one of the authors to evaluate the effects of errors in the alignment of the easy axis of the charge sheet equivalent material (CSEM) on the magnetic fields in the insertion device and thus on the electron beam and on the synchrotron radiation that is produced. The reason for concern regarding the effects of this characteristic of the material on device performance is the observation of field errors localized in the region between poles in devices such as the Transverse Optical Klystron (TOK) at the NSLS at Brookhaven National Laboratory and the Beam Line X Wiggler at the Stanford Synchrotron Radiation Laboratory [5].…”