| Paper | Title | Page |
|---|---|---|
| TUYFI02 | Latest Developments on Insertion Devices | 969 |
|
||
| A review will be carried out of the developments on Insertion Devices that have taken place world wide in the last few years. These include the development of long period electro-magnet undulators, the operational results of a number of Apple-II undulators, the development of superconducting short period multipole wigglers, as well as the construction and operation of several in-vacuum undulators. The construction of a large number of competitive middle energy synchrotron sources in the hard X-ray range means that the need to increase the photon energy in the fundamental peak of an undulator is becoming a very important issue. Two main development strategies are currently being investigated. One consists of using superconducting undulator technology, the other of a further refinement of the in-vacuum undulator permanent magnet technology with cryogenic cooling of the magnetic assembly. The issues and challenges that are part of each approach will be presented, together with the latest results. | ||
|
Transparencies | |
| THPLS011 | Operation and Recent Development at the ESRF | 3290 |
|
||
| We report on the achieved performance of the ESRF storage ring as well as developments accomplished or underway. A new hybrid filling mode based on groups of bunches and a 4-bunch filling pattern are now delivered to the users. Following the increasing demand of users for beam stability, the fast orbit feedback has been upgraded. The installation of 5 m-long, 8 mm vertical aperture NEG coated aluminum chambers is progressing at a rate of one chamber per shutdown. The increase in current from 200 to 300 mA is being prepared; however, operation in this mode is still impaired by HOM driven longitudinal instabilities. To overcome this difficulty, a longitudinal feedback is being commissioned. HOM damped cavities are also under study to possibly replace the existing five-cell cavities. The policy of preventive maintenance has been continued. However, in 2005 the machine availability was affected by water leaks occurring on front-end absorbers and on one dipole crotch absorber. The crotch absorbers suffer all from the same erosion process that could be delayed by a systematic vertical realignment, leaving time for procurement and replacement of the entire pool. | ||
| THPLS119 | Development of a Cryogenic Permanent Magnet In-vacuum Undulator at the ESRF | 3559 |
|
||
|
Lowering the temperature of NdFeB materials increases their field remanence and intrinsic coercivity*. This property is potentially interesting for the construction of cryogenic permanent in-vacuum undulators (CPMU)**. Around 150K, the coercivity is increased to such an extent that the NdFeB material is comparable to the Sm2Co17 as far as resistance to radiation damages is concerned. The improvement in field remanence is less remarkable (15% at 150K) and is dominated by a reversible Spin Reorientation Transition (SRT) occurring around 135K. Below this temperature, the remanence decreases. The complete magnetization curves of NdFeB material measured at different cryogenic temperatures are presented. Non-linear models have been constructed and used in the RADIA code in order to compute the field performance of a hybrid NdFeB in-vacuum undulator. A prototype CPMU is presently under construction at the ESRF. It has a period of 18mm and a magnetic length of 2m. The field integral and local field measurements of the cryogenic device require new systems operated in vacuum. A stretched wire bench and a hall probe bench are under construction; their main characteristics will be presented.
*D. Givord et al. Analysis of hysteresis loops in NdFeB sintered magnets, J. Appl. Phys. 60(9) (3263-3265).**T. Hara et al. Cryogenic permanent undulator, Phys.rev. ST AB volume 7 050702 (2004). |