Twin Aperture Quadrupole Research Articles

Development of the CEPC collider prototype magnets

A Circular Electron Positron Collider (CEPC) with a circumference of about 100 km and a beam energy up to 120 GeV is proposed to be constructed in China. Over 80% of the collider ring is covered by conventional magnets. Most dipole and quadrupole magnets are twin aperture magnets with an inter-beam separation of 350 mm. Two 1-meter-long twin aperture prototype magnets are designed and manufactured. One is a combined dipole–sextupole magnet with aluminum bus bar coils, and the other one is a twin aperture quadrupole magnet with a DT4 compensation sheet to reduce the crosstalk effect between the two apertures. The design, fabrication and magnetic measurement of two prototype magnets are described in this paper.

Analysis of lamination measurements for CERN's twin aperture quadrupoles

The European Organization for Nuclear Research (CERN) is constructing the Large Hadron Collider (LHC). The LHC's cleaning insertions require 48 twin aperture resistive quadrupoles. The laminations for these magnets are punched from low carbon steel sheet 1.5 mm thick. To check the quality of the laminations, samples are regularly collected and measured. This paper describes how these measurements are analyzed. This work is part of the Canadian contribution to the LHC.

Performance of the single and twin-aperture models of the 6 kA superconducting quadrupole for the LHC insertions

The LHC dispersion suppressors and matching sections will be equipped with individually powered superconducting quadrupoles with an aperture of 56 mm. In order to optimise the parameters and cost of the magnets and of their powering, the quadrupole has been designed on the basis of an 8.2 mm wide Rutherford-type cable for a nominal current of 5300 A, corresponding to a gradient of 200 T/m at 1.9 K. In order to validate the design two 1-m single-aperture quadrupoles and one twin-aperture quadrupole have been built and tested. In this report we describe the construction features of the magnets and present the results of the magnet tests.

Design and fabrication of a 1 m model of the 70 mm bore twin aperture superconducting quadrupole for the LHC insertions

For reasons of geometrical acceptance, 70 mm bore twin aperture quadrupoles are required in the LHC insertions. For an operating gradient of 160 T/m at 4.5 K, a design based on a four layer coil wound from two graded 8.2 mm NbTi conductors has been developed. Three 1 m single aperture quadrupoles of this design have been built and successfully tested. Thereafter, the magnets have been disassembled and the coils re-collared using self-supporting collars. In this paper, we describe the design features of the twin aperture quadrupole, and report on the initial collaring tests and procedures for collaring and final assembly of the 1 m magnet.

Construction of the new prototype of main quadrupole cold masses for the arc short straight sections of LHC

Each cold mass of the short straight sections in the eight LHC arcs will contain a 3.25 m long twin aperture quadrupole of a nominal gradient of 223 T/m. This magnet will be aligned in a 5.3 m long inertia tube together with auxiliary magnets on each end. On the quadrupole connection end either a pair of 38 cm long octupole or trim quadrupole magnets will be mounted, on the other end there will be combined sextupole-dipole correctors with a yoke length of 1.26 m. The powering of the main quadrupoles will be assured by two pairs of copper stabilized superconducting bus-bars placed inside the cold mass next to the bus-bars for the main dipole magnets. Each of the two quadrupole apertures will be connected to its quench protection diode. The construction of three prototypes has been entrusted to the CEA/Saclay laboratory, in the frame of the special French contribution to the LHC project. The first cold mass prototype has been completed and warm-measured for its multipole content at CEA. The second cold mass is presently under completion. The paper reviews the experience with the development of the quadrupole coils and cold mass construction and gives the results of the first warm magnetic measurements. An outlook for the series manufacture of the 400 are quadrupole magnets and their cold masses for the LHC machine completes the report.

Twin aperture quadrupoles for the LHC cleaning insertions

Twin-aperture quadrupoles are proposed for the FODO structure of the LHC cleaning insertions. These quadrupoles will be of the conventional type with laminated iron cores and normal conducting copper coils. Their somewhat unconventional design is described and the main characteristics are given.

Cryogenic tests of the first two LHC quadrupole prototypes

Two LHC (Large Hadron Collider) twin aperture quadrupole superconducting magnet prototypes were constructed at CEA Saclay, in the framework of a collaboration agreement between CERN and CEA in Saclay. Their main characteristics are: 3.05 m length, 56 mm coil aperture, 180 mm between the two apertures, 252 T/m nominal gradient at 15060 A. They have been tested and measured in the 1.8 K Saclay test facility in a horizontal cryostat. The magnets are instrumented in order to investigate their behaviour during cool-down, stand-by, powering and current ramping, quenching and warming-up. The paper presents a summary of the cryogenic, mechanical, pressure and electrical measurements. The 15060 A nominal current was reached with little training. The quench protection heaters are efficient down to 3000 A. Losses during ramping up and down are reported.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

The superconducting magnet system for the LHC

The new facility for the Large Hadron Collider (LHC) will mainly consist of a 27-km-long double ring of high-field superconducting magnets installed in the Large Electron-Positron Collider (LEP) tunnel, above the LEP machine components. The magnet system comprises nearly 2000 twin-aperture, 8-10-T, 10-m-long, dipole bending magnets, more than 500 250-T/m, twin-aperture quadrupoles, and a very large number of other superconducting magnetic components. A general description of the system is given together with the main features of the design of the regular lattice magnets. Also described is the present state of the magnet R&D program, which, after the successful phase of short model magnets, is now aimed at the construction of a full prototype 100-m-long cell for the LHC machine.