CONTROL OF NONLINEAR DYNAMICS BY ACTIVE AND PASSIVE METHODS FOR THE NSLS-II INSERTION DEVICES

Nonlinear effects from insertion devices are potentially a limiting factor for the electron beam quality of modern ring-based light sources, i.e., the on and off-dynamical aperture, leading to reduced injection efficiency and beam lifetime. These effects can be modelled by e.g. kick maps ({approx}1/{gamma}{sup 2}) and controlled by e.g. first-order thin or thick magnetic kicks introduced by 'magic fingers,' 'L-shims,' or 'current strips'. However, due to physical or technological constraints, these corrections are typically only partial. Therefore, a precise model is needed to correctly minimize the residual nonlinear effects for the entire system. We outline a systematic method for integrated design and rapid prototyping based on evaluation of the 3D magnetic field and control of the local trajectory with RADIA, and particle tracking with Tracy-3 for validation. The optimal geometry for the compensating magnetic fields is determined from the results of these simulations using a combination of linear algebra and genetic optimization

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

DEVELOPMENT OF A PrFeB CRYOGENIC UNDULATOR AT NSLS-II

Abstract Recent cryogenic undulators use Praseodymium-IronBoron (PrFeB) magnets cooled down to 80K. The main drawback of the PrFeB magnet grades developed so far are their relatively low coercive field at ambient temperature, below 2 T which prevents PrFeB based cryogenic undulator from baking. Some precautions are required during the undulator assembling and shimming to ensure Ultra High Vacuum (UHV) compatibility. However Hitachi Metal Industry (HMI) recently developed two different grades of PrFeB magnet with large coercive field but at the expense of the remanent field. The magnetization curves have been measured from 40 K up to 400 K to determine the field increase and to investigate the magnet withstanding to baking. An In Vacuum Undulator (IVU) prototype has also been baked. Magnetic measurements before and after baking are also presented