Initial results from an in-vacuum undulator in the NSLS X-ray ring

The magnetic field of a staggered-array undulator using a bulk high-temperature superconductor is calculated by analytical and numerical methods. Analytical formulas for the undulator field and the solenoid field required to generate the undulator field are derived from a simple two-dimensional model. The analytical calculation shows the degree of dependence of these fields on the undulator parameters, the generation of a high undulator field proportional to the critical current density of the bulk superconductor, and the good tunability of the undulator field over a wide range of values. The numerical calculation is performed in a three-dimensional geometry by two methods: the center field and energy minimization methods. The latter treats the current distribution inside the bulk, whereas the former neglects it as a natural extension of the analytical model. The calculation also reveals the dependence of the fields on the undulator parameters arising from the current distribution. From the comparison with experimental results, we find that the latter method reproduces the experimental results well, which indicates the importance of the current distribution inside the bulk. Therefore, we derive a semiempirical formula for the required solenoid field by modifying the analytical formula using the numerical results so as to include the effect of the current distribution. The semiempirical formula reproduces the numerical result with an error of 3%. Finally, we estimate the magnetic performance of the undulator as an example of using the formulas and values presented in this paper. The estimation shows that an undulator field twice as large as that of the present in-vacuum undulator but with an equal period and gap can be obtained at a temperature of approximately 20-40 K, and that deflection parameters (K values) of 1 and 2 can be achieved with periods of 5 and 10 mm at approximately 4-20 K.

Section: A Basic Characteristics Of Fieldsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Magnetic property of a staggered-array undulator using a bulk high-temperature superconductor

Kinjo

Mishima

Choi

et al. 2014

“…In recent years, short period undulators became widely used in synchrotron radiation facilities, because they increase the number of periods in a unit undulator length and as a consequence, they generate brighter synchrotron radiation. Moreover, a short undulator periodicity enables the emission of high energy photons, and therefore it opens the way for an x-ray beam line operation in medium size synchrotron radiation facilities, such as SLS and NSLS [1,2]. For the same reason, a short period undulator is very attractive for SASE-FEL facilities, since it lowers the electron beam energy necessary for an x-ray FEL operation.…”

Section: Introductionmentioning

confidence: 99%

“…One big advance for the realization of short period undulators has been the in-vacuum design, which accommodates permanent magnet arrays inside vacuum and eliminates the physical limitation of the magnetic gap due to the vacuum chamber [4]. In-vacuum undulators have been successfully operated for years in many synchrotron radiation facilities [1,2,4,5].…”

Section: Introductionmentioning

confidence: 99%

Cryogenic permanent magnet undulators

Hara

Tanaka

Kitamura

et al. 2004

147

In order to obtain high magnetic fields in a short period undulator, superconductive undulators have been actively investigated in recent years. In this paper, however, we propose a new approach, the cryogenic permanent magnet undulator (CPMU) design, using permanent magnets at the cryogenic temperature of liquid nitrogen or higher. This cryogenic scheme can be easily adapted to currently existing in-vacuum undulators and it improves the magnetic field performance by 30%-50%. Unlike superconductive undulators operating around the liquid helium temperature, there is no big technological difficulty such as the thermal budget problem. In addition, existing field correction techniques are applicable to the CPMUs. Since there is no quench in the CPMUs, the operation of the CPMUs has the same reliability as conventional permanent magnet undulators.

“…The current trend in undulator developments is toward shortening the magnetic period to obtain SR with shorter wavelength [5][6][7][8]. Therefore, much effort has been made to develop short period undulators such as an in-vacuum undulator [9,10], a superconducting undulator (SCU) working around liquid helium temperature [11,12], and a cryogenic permanent magnet undulator (cryoundulator) [13].…”

Section: Introductionmentioning

confidence: 99%

Application of high-temperature superconducting permanent magnets to synchrotron radiation sources

Tanaka

Hara

Kitamura

et al. 2004

A simple scheme for field enhancement in synchrotron radiation sources such as undulators and wigglers is proposed, which is based on the fundamental nature of the superconducting loop where the magnetic flux is preserved. A superconductor ring placed to enclose the magnetic pole works as a kind of permanent magnet. The magnetization is performed by electromagnetic induction brought by the opening movement of the magnetic gap. Since neither additional external power supplies nor current leads are necessary, high-temperature bulk superconductors can easily be implemented in this scheme. Calculations to check the effectiveness of the new concept show that the critical current density of the superconductor is crucial to the performance of the synchrotron radiation sources based on this concept. Experiments were performed to verify the principle of the proposed scheme, which gave promising results to strongly support it.