Engineering topics

Rakowsky, G

Publications and source records attributed to Rakowsky, G.

3 records

DOE OSTI2011

CURRENT STATUS OF INSERTION DEVICE DEVELOPMENT AT THE NSLS-II AND ITS FUTURE PLANS

National Synchrotron Light Source-II (NSLS-II) project is currently under construction. Procurement of various insertion devices (IDs) has begun. This ring assumes a very high beam stability requirement which imposes tighter field specifications on insertion devices (IDs) compared to the rings of previous generation. The state of the art ID Magnetic Measurement Facility is being set up in order to be able to certify the stringent requirements on the magnetic field of NSLS-II IDs. The IDs in the project baseline scope include six 3.5m long damping wigglers (DWs) with 100mm period length and 15mm pole gap, two 2.0m Elliptically Polarizing Undulator (EPU) with 49mm period and 11.5mm minimum magnetic gap, two 3.0m long 20mm period and one 1.5m long 21mm period IVU, which the minimum gap of these is 5mm and 5.5mm, respectively. Recently a special device for inelastic X-ray scattering (IXS) beamline has been added to the collection of baseline devices. Three pole wigglers with a 28mm magnetic gap and a peak field over 1 Tesla will be utilized to accommodate the users of the type of radiation which is currently produced with bending magnets at the NSLS.

43 PARTICLE ACCELERATORS↗

DOE OSTI2010

PROGRESS ON INSERTION DEVICE RELATED ACTIVITIES AT THE NSLS-II AND ITS FUTURE PLANS

National Synchrotron Light Source-II (NSLS-II) project is now in the construction stage. A new insertion device (ID) magnetic measurement facility (MMF) is being set up at Brookhaven National Laboratory in order to satisfy the stringent requirement on the magnetic field measurement of IDs. ISO-Class7 temperature stabilized clean room is being constructed for this purpose. A state-of-the-art Hall probe bench and integrated field measurement system will be installed therein. IDs in the project baseline scope include six damping wigglers, two elliptically polarizing undulators (EPUs), three 3.0m long in-vacuum undulators (IVUs) and one 1.5m long IVU. Three-pole wigglers with peak field over 1 Tesla will be utilized to accommodate the users of bending magnet radiation at the NSLS. Future plans includes: (1) an in-vacuum magnetic measurement system, (2) use of PrFeB magnet for improved cryo undulator, (3) development of advanced optimization program for sorting and shimming of IDs, (4) development of a closed loop He gas refrigerator, (5) switchable quasi-periodic EPU. Design features of the baseline devices, IDMMF and the future plans for NSLS-II ID activities are described.

43 PARTICLE ACCELERATORS↗

DOE OSTI2010

A simple model based magnet sorting algorithm for planar hybrid undulators

Various magnet sorting strategies have been used to optimize undulator performance, ranging from intuitive pairing of high- and low-strength magnets, to full 3D FEM simulation with 3-axis Helmholtz coil magnet data. In the extreme, swapping magnets in a full field model to minimize trajectory wander and rms phase error can be time consuming. This paper presents a simpler approach, extending the field error signature concept to obtain trajectory displacement, kick angle and phase error signatures for each component of magnetization error from a Radia model of a short hybrid-PM undulator. We demonstrate that steering errors and phase errors are essentially decoupled and scalable from measured X, Y and Z components of magnetization. Then, for any given sequence of magnets, rms trajectory and phase errors are obtained from simple cumulative sums of the scaled displacements and phase errors. The cost function (a weighted sum of these errors) is then minimized by swapping magnets, using one's favorite optimization algorithm. This approach was applied recently at NSLS to a short in-vacuum undulator, which required no subsequent trajectory or phase shimming. Trajectory and phase signatures are also obtained for some mechanical errors, to guide 'virtual shimming' and specifying mechanical tolerances. Some simple inhomogeneities are modeled to assess their error contributions.

43 PARTICLE ACCELERATORS↗