Cryogenic Design of a PrFeB Based Undulator

A PrFeB based cryogenic undulator has been built at Helmholtz Zentrum Berlin HZB in collaboration with the Ludwig Maximilian University München LMU . LMU will operate the undulator at a laser plasma accelerator at the Max Planck Institut für Quantenoptik in Garching. The 20 period device has a period length of 9mm and a fixed gap of 2.5mm. The operation of a small gap device at a high emittance electron beam requires stable magnetic material. A high coercivity is achieved with PrFeB material cooled down to 20 30K. In this paper we present the mechanic, magnetic and cryogenic design and compare predictions with measured dat

Cryogenic System for BERLinPro

In 2010 Helmholtz Zentrum Berlin HZB received funding to design and build the Berlin Energy Recovery Linac Project BERLinPro. The goal of this compact Energy recovery linac ERL is to develop the accelerator physics and technology required to generate and accelerate a 100 mA, 1 mm mrad emittance electron beam. The BERLinPro know how can then be transferred to various ERL based applications. All accelerating RF cavities including the electron source are based on superconducting technology operated at 1.8 K. A Linde L700 helium liquefier is supplying 4.5 K helium. The subatmospheric pressure of 16 mbar of the helium bath of the cavities will be achieved by pumping with a set of cold compressors and warm vacuum pumps. While the L700 is already in operating, the 1.8 K system and the helium transfer system are in design phase

Manipulating the Intrinsic Quality Factor by Thermal Cycling and Magnetic Fields

For CW applications of superconducting cavities, obtaining a high quality factor is an important issue, since the required cryogenic power drops inversely proportional to Q0. Q0 is limited by BCS losses and static losses, i.e. impurities and trapped magnetic flux. With sufficient magnetic shielding for TESLA type cavities, typical values of 2 1010 are being achieved at 1.8K operating temperature. The flux trapping was monitored by cooling the cavity at different ambient magnetic fields. In another experiment we have observed a significant increase in the Q0 value of up to 50 when subjecting the cavity to an additional cryogenic cooling cycle. Quantitative results are being presented and possible explanations for the effects are being discusse

Status of the Berlin Energy Recovery Project BERLinPro

After the funding approval in late 2010 and the official project start in 2011, a mayor review of the critical design parameters took place in summer 2011. Following the strong advice of the first MAC meeting, the final energy has been reduced to 50 MeV in order to stay within the tight financial frame. As a result primarily the cold super conducting radio frequency SRF systems and the injection had to be redesigned. In spring 2012 a Conceptual Design Report will be published that mirrors the present state of the project. This article summons critical strategic and design decision

Status of the HZB ERL Prototype bERLinPro

The Berlin Energy Recovery Linac Prototype BERLinPro is to be constructed at the Helmholtz Zentrum site in Berlin. The aim of the project is to expand the required accelerator physics and technology knowledge mandatory for the generation of a high current 100 mA , high brilliance norm. emittance below 1 mm mrad cw electron beam. Since the funding decision in October 2010 the project has entered a phase of detailed planning. Hardware specifications have been defined and various components have been ordered. Furthermore, extensive tests of principal superconducting accelerator components successfully demonstrated the envisaged hardware performance. A summary of the most recent activities together with the details of the project timeline for the coming years are given in this pape