Field Measurements of Magnets for Modern SR Sources and FEL
Magnets for modern accelerators and storage rings may have a rather complex field distribution and strict quality requirements. The Budker Institute of Nuclear Physics (Novosibirsk, Russia) is a well-known producer of magnets for various accelerator projects worldwide. This paper describes our magnet measurement facility with examples of NSLS-II booster magnets, small-aperture X-FEL quadrupoles, and PETRA-III dipoles. NSLS-II booster dipoles have quadrupole and sextupole components with a rather high field quality of 1 · 10-3 in the good field region of ±2 cm, providing booster operation at energy from 170 MeV to 3.15 GeV with a 2-Hz repetition rate. We designed a special bench with a ceramic rotation coil to measure X-FEL quadrupoles. The equipment provided measurements of the magnetic axis with accuracy better than 5 μm. We used the system of three temperature-stabilized Hall sensor arrays distributed vertically to obtain a three-dimensional field map from a single measurement of PETRA-III dipole magnets.
MAGNETIC MEASUREMENT OF THE NSLS-II BOOSTER DIPOLE WITH COMBINE FUNCTIONS*
The magnetic system of NSLS II Booster is designed, manufactured and tested in BINP, Russia. The booster dipole incorporates quadrupole and sextupole components and has rather tight requirement for the field quality ±2·10 -4 in the good field region ±2 cm. The magnets provide the booster operation in the energy range from 170 MeV to 3.15 GeV with 2 Hz repetition frequency. This report contains description of the magnetic measurement bench and the results achieved for the DC case; AC magnet test including vacuum chamber influence is described in [1]. INTRODUTION The NSLS II is a third generation light source under construction at Brookhaven National Laboratory [2]. The project includes a highly optimized 3 GeV electron storage ring, linac pre-injector and full-energy boostersynchrotron. Budker Institute of Nuclear Physics (BINP) builds booster for NSLS-II. The booster should accelerate the electron beam continuously and reliably from minimum injection energy of 170 MeV to maximum extraction energy of 3.15 GeV with average beam current of 20 mA. The booster shall be capable of multi-bunch and single bunch operation. The booster BF (BD) dipoles contains focusing (defocusing) quadrupole and sextupole components but should provide rather high field quality ±2·10 -4 in the good field region ±2 cm in the whole energy range Dipole parameters are listed in Table 1.
Thermally Induced Dynamics of Satellite Solar Panels
Thermally induced structural motions are known to affect the attitude dynamics of low Earth orbiting satellites during eclipse transitions. Motions of e exible appendages such as solar panels lead to rigid body rotations of the entire satellite because the total angular momentum of the system is conserved. These potentially large attitude disturbances may violate pointing accuracy and jitter requirements. One type of thermally induced dynamics exhibited by solar panels is thermal snap. The Upper Atmosphere Research Satellite is a prominent example of a satellite that experiences thermal snap disturbances during eclipse transitions. This paper describes recent studies of thermally induced dynamicsof solarpanels, including an analysisofsatelliteattitudedynamics resulting from thermally induced structural motions and a laboratory investigation of the thermal-structural performance of a satellite solar panel. Analytical and experimental results demonstrate thermal bending deformations with acceleration transients that have characteristic thermal snap disturbance histories in response to rapid changes in heating. The studies show that solar panel thermal snap disturbances are caused by through-the-thickness temperature differences that vary at a nonconstant rate. Finite element analysis correctly predicts the thermal snap phenomenon observed in the solar panel experiments.