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Title: Undulator Field Integral Measurements

Abstract

The LCLS undulator field integrals must be very small so that the beam trajectory slope and offset stay within tolerance. In order to make accurate measurements of the small field integrals, a long coil will be used. This note describes the design of the coil measurement system.

Authors:
Publication Date:
Research Org.:
SLAC National Accelerator Lab., Menlo Park, CA (United States)
Sponsoring Org.:
USDOE
OSTI Identifier:
1000323
Report Number(s):
SLAC-TN-10-076
TRN: US1100085
DOE Contract Number:
AC02-76SF00515
Resource Type:
Technical Report
Country of Publication:
United States
Language:
English
Subject:
43 PARTICLE ACCELERATORS; 47 OTHER INSTRUMENTATION; DESIGN; WIGGLER MAGNETS; LIGHT SOURCES; FREE ELECTRON LASERS; LINEAR ACCELERATORS; INTEGRALS; MEASURING METHODS; MEASURING INSTRUMENTS; XFEL

Citation Formats

Wolf, Zachary. Undulator Field Integral Measurements. United States: N. p., 2010. Web. doi:10.2172/1000323.
Wolf, Zachary. Undulator Field Integral Measurements. United States. doi:10.2172/1000323.
Wolf, Zachary. Tue . "Undulator Field Integral Measurements". United States. doi:10.2172/1000323. https://www.osti.gov/servlets/purl/1000323.
@article{osti_1000323,
title = {Undulator Field Integral Measurements},
author = {Wolf, Zachary},
abstractNote = {The LCLS undulator field integrals must be very small so that the beam trajectory slope and offset stay within tolerance. In order to make accurate measurements of the small field integrals, a long coil will be used. This note describes the design of the coil measurement system.},
doi = {10.2172/1000323},
journal = {},
number = ,
volume = ,
place = {United States},
year = {Tue Dec 07 00:00:00 EST 2010},
month = {Tue Dec 07 00:00:00 EST 2010}
}

Technical Report:

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  • Measurements of the multipole content of the Mini-Undulator magnet have been made with two different integrating wire techniques. Both measurements used 43 strand Litz wire stretched along the length of the magnet within the magnet gap. In the first technique, the wire motion was purely translational, while in the second technique the wire was moved along a circular path. The induced voltage in the Litz wire was input into a Walker integrator, and the integrator output was analyzed as a function of wire position for determination of the multipole content of the magnetic field. The mini-undulator magnet is a 10more » period, 80 mm per period hybrid insertion device. For all the data contained herein the magnet gap was set at 49 mm. In the mini-undulator magnet, the iron poles are 18mm x 32mm x 86mm, and the Samarium Cobalt permanent magnet blocks are 22mm x 21mm x 110mm. For this magnet, which is a shortened prototype for the NSLS Soft X-Ray Undulator Magnet, the undulator parameter K = 0.934 B(Tesla){lambda}(cm), and B(tesla) = 0.534/sinh({pi}Gap/{lambda}). At a gap of 49 mm, the magnetic field is 1590 Gauss. The 43 strand Litz wire is supported on motorized x-y stages at both ends of the magnet, which are controlled by stepping motors through a Labview program. One leg of the wire loop is within the magnet gap, and the other leg is in an essentially field free region. Only the leg of the wire loop within the magnet gap is moved during data acquisition. The Litz wire is tensioned with 11.5 pounds, and is wrapped with a supporting tape which is itself tensioned with 18 pounds through a spring and turnbuckle arrangement. With this setup the sag in the wire over the 72 inch span is less than 0.003 inches, as measured with survey instruments. Photographs of the setup are shown.« less
  • Measurements of the multipole content of the Mini-Undulator magnet have been made with two different integrating wire techniques. Both measurements used 43 strand Litz wire stretched along the length of the magnet within the magnet gap. In the first technique, the wire motion was purely translational, while in the second technique the wire was moved along a circular path. The induced voltage in the Litz wire was input into a Walker integrator, and the integrator output was analyzed as a function of wire position for determination of the multipole content of the magnetic field. The mini-undulator magnet is a 10more » period, 80 mm per period hybrid insertion device. For all the data contained herein the magnet gap was set at 49 mm. In the mini-undulator magnet, the iron poles are 18mm x 32mm x 86 mm, and the Samarium Cobalt permanent magnet blocks are 22mm x 21mm x 110mm. For this magnet, which is a shortened prototype for the NSLS Soft X-Ray Undulator Magnet, the undulator parameter K = 0.934 B (Tesla){lambda}(cm), and B(tesla) = 0.534/sinh({pi}Gap/{lambda}). At a gap of 49 mm, the magnetic field is 1590 Gauss.« less
  • The duct work and cable trays present in the undulator hall facility are made out of potentially magnetically active materials. This note describes a measurement done to make a comparison between the fields in the undulator hall with the duct work and cable trays present and in the Magnetic Measurement Facility. In order for the undulators to have the proper tuning, the background magnetic field in the Undulator Hall must agree with the background field in the Magnetic Measurements Facility within 0.5 gauss. To verify that this was the case, measurements were taken along the length of the undulator hall,more » and the point measurements were compared to the mean field which was measured on the MMF test bench. This set of measurements was conducted with most of the cable trays and duct work in place, but without any of the magnet stands in place.« less
  • The Soft X-Ray Undulator Magnet was installed in the X-ray Ring (X1 beam line) at the National Synchrotron Light Source at Brookhaven National Laboratory in June 1988. Prior to its installation extensive magnetic measurements were performed at the NSLS Magnetic Measurements Lab in order to determine the operating values for the end corrector currents, the field quality, and the integrated multipoles associated with the magnet as a function of gap. This report is intended to summarize the results of these measurements. The iron poles are 18mm {times} 32mm {times} 86mm, and the Samarium Cobalt permanent magnet blocks are 22mm {times}more » 21mm {times} 110mm. In each of the magnet halves there are 76 slots, 70 of which were filled with two magnets per slot, and 6 of which were left empty (3 each on the upstream and downstream ends of the magnet). These slots were left empty in order to approximate an infinitely long magnet in the algorithm for the magnet block sorting. The magnet period is 80mm, and the gap range is 31--100mm, with field values of 3500 and 200 Gauss respectively. For this gap range the undulator parameter K, where K = 0.934 B(Tesla) {lambda}(cm), ranges from 2.6 to 0.15. 14 figs., 5 tabs.« less
  • The Advanced Photon Source (APS), a 7-GeV positron storage ring, will have as many as 34 straight sections available for installation of multiple insertion devices (IDs). The size and the taper of the gap of the IDs will be able to be varied to tune the energy of the emitted radiation to the experiments. The IDs must not affect the particle beam motion. Therefore, the disturbances should be kept within tight boundaries to assure that the ring performance parameters are maintained and that the emitted radiation shows little degradation from an ideal device. These requirements are derived from the stabilitymore » criteria of the beam to be stable within 10% of the emittance: The requirements cannot be met without using closed loop orbit compensation. With such a system installed, it is reasonable to relax the requirements on the ID magnetic field performance.« less