Development of a MODEL superconducting helical undulator for the ILC positron source

Abstract

The helical undulator for the proposed International Linear Collider (ILC) positron source requires highpermeability steel poles and superconducting coils to meet the ILC parameters. A short-model undulator with a period of 14 mm was designed, fabricated including highpermeability steel poles, and tested in LHe. The ends of the model were designed to wind the Nb 3 Sn double helix without any conductor joints. After a few quenches in the first excitation test, the current density in the coil reached 1.28 kA/mm 2 , which was approximately 90% of the estimated short-sample critical current density. The periodic on-axis fields were mapped at two azimuth angles. Excluding the end fields, the standard deviation of the field amplitudes and higher harmonic coefficients for the periodic field were less than 7 × 10 -3 and 5 × 10 -3 , respectively.

A Model Superconducting Helical Undulator Wound Using a Wind and React ${\rm MgB}_{2}$ Multifilamentary Wire

“…Finally, we have multiplied the measured field in the bore by a factor of 3 to make an estimate of the field at the winding. This factor is approximate and is taken from the paper of Kim et al [7], who made measurements on and also made an FEM model of an Fig. 9.…”

“…The blue line is the B vs I as determined by the short sample helical coil measurement for these strands. The dashed line is an estimation of the field at the winding, simply made using a factor of 3 multiplicative factor (estimated from Kim [7]). Values are in rough agreement.…”

“…We based our helical undulator design on one of the undulator models constructed by Argonne National Laboratory (ANL) using superconductor wire [7]. The model undulator was based on parameters listed in Table I, see Fig.…”

Design of ${\rm Nb}_{3}{\rm Sn}$-Based Short Period Model Superconducting Helical Undulator

“…The extensive research conducted in support of the TTF's 14 mm superconducting undulator development by research groups at the Rutherford-Appleton and other European laboratories [2]- [6] has stimulated parallel programs both at the above laboratories and at Argonne National Laboratory (ANL) [7]- [9] in support of the ILC's 10-mm-undulator requirements. The demands of ILC are more demanding than those of TESLA-a higher central flux density, , and a correspondingly shorter period.…”

“…The demands of ILC are more demanding than those of TESLA-a higher central flux density, , and a correspondingly shorter period. Using the helical undulator, which for a given field-at-winding delivers twice the on-axis field [7], [10] energy and the energy of relativistic electrons is given by:…”