Design and Manufacturing Main Linac Superconducting Quadrupole for ILC at Fermilab

Abstract

Abstract-The design and manufacturing of the first model of an International Linear Collider (ILC) Main Linac superconducting quadrupole is in progress at Fermilab. The quadrupole has a 78 mm aperture, a 36 T integrated gradient, and a cold mass length of 700 mm. A superferric magnet configuration with iron poles and four racetrack coils was chosen based on magnet performance, cost, and reliability considerations. Each coil is wound using enamel insulated, 0.5 mm diameter, NbTi superconductor. The quadrupole package also includes shell type dipole steering coils. The results of the quadrupole design, including magnetic and mechanical analyses, are presented. Specific issues related to the quadrupole magnetic center stability, superconductor magnetization and mechanical stability are discussed and analyzed. The magnet quench protection system, current leads, and mounting the quadrupole inside ILC Main Linac cryomodule will also be briefly discussed.

The International Linear Collider Technical Design Report - Volume 3.II: Accelerator Baseline Design

“…RF cables bring the signals from the field pickup and the HOM antennas (See Section 3.3.3) to the LLRF control system outside the cryomodule for the control of the cavity field amplitude and phase and to extract HOM power from the 2 K level. Manually operated valves 42 ILC Technical Design Report: Volume 3, Part II…”

“…Because of superconductor magnetisation effects (cross coupling) between combined quadrupole and dipole coils [42,43], the quadrupole and dipole correctors are separated.…”

Conduction Cooling Test of a Splittable Quadrupole for ILC Cryomodules

“…HE development of a focusing element that meets all requirements for ILC [1] Main Linac cryomodules has challenged the superconducting magnet community for a number of years [2]- [6]. Of those requirements, shown in Table I, keeping the magnetic axis position stable to within 5 microns during a 20% field strength variation is perhaps the most difficult.…”

“…Of those requirements, shown in Table I, keeping the magnetic axis position stable to within 5 microns during a 20% field strength variation is perhaps the most difficult. One design, made at Fermilab, is based upon superconducting racetrack coils supported within a laminated iron yoke structure; the design concept and test results for the first model magnet of this type (RTQ01) have been previously reported [2]- [3]. Subsequently this design has evolved in two important ways: first, the steering dipole coils were removed to a separate corrector element, to eliminate magnetization effects that complicate the center position dependence on coil excitation history.…”

A Novel Design of Iron Dominated Superconducting Multipole Magnets With Circular Coils

“…The magnet for TESLA Test Facility was based on shell type coils [4]. For ILC [1], XFEL [2], and Project-X [3] relatively weak quadrupoles are based on racetrack type coils where the magnetic field is shaped by iron poles [4][5][6][7][8]. Because the beam size in these accelerators is very small, this approach is more efficient from a technological point of view.…”