Development, Fabrication and Test of a Superconducting Quadrupole magnet with High Gradient (200 T/M) and Large Aperture (7 CM), Based on Nb3Sn Superconductor
Tech Area / Field
- PHY-PFA/Particles, Fields and Accelerator Physics/Physics
3 Approved without Funding
Institute for High Energy Physics (IHEP), Russia, Moscow reg., Protvino
- All-Russian Scientific Research Institute of Non-Organic Materials named after A. Bochvar, Russia, Moscow
- ITER EDA / Naka Joint Work Site, Japan, Naka\nCEA / DSM / CEN Saclay, France, Saclay\nDESY, Germany, Hamburg\nFermilab (Fermi National Accelerator Laboratory), USA, IL, Batavia
Project summaryA program for upgrading the capability of colliding beam operation of the superconducting accelerator at Fermi National Accelerator Laboratory (FNAL, Batavia, Illinois, USA) is presently being pursued. The purpose of the upgrade program is to improve the luminosity and reliability of operation of the Tevatron. This is the highest energy superconducting accelerator in the world, conducting proton/antiproton experiments up to 1800 GeV energy in the center-of-mass.
On March 1995 about 60 events interpreted as top quark from 6 trillions proton-antiproton collisions were detected by two experiments at Tevatron. The top quark is the final letter in the alphabet of Standard Model particles.
The further investigation of these particles properties needs the upgrading of existing accelerating-storage complex. Some of the upgrade program has already been started, such as major upgrades of the two colliding detectors and construction of a major new 150 GeV injector. Another possible part of the upgrade is increasing the strength of the focusing elements of the interaction regions, in order to create more space for shielding and instrumentation, and to increase the luminosity by decreasing the beam size at the interaction point.
In order to accomplish this better performance, superconducting quadruples with increased gradient and field quality is required: an operating field gradient of 200 T/m (implying a maximum gradient of 220-250 T/m), and a magnet aperture of at least 70 mm. The present Tevatron interaction region quadruples have a gradient of 140 T/m at 4.5K, with an aperture of 76 mm. There are two possible ways to achieve the required higher gradient: using quadruples made with NbTi superconductor operating at a temperature of superfluid helium (1.8 K) or using a quadruple made from Nb3Sn superconductor, which could satisfy the requirements operating at 4.5K.
The Tevatron presently operates at 4.5 K. Changing the cryogenic system at the interaction insertions to operate at 1.8 К is though to be quite costly - many millions of dollars. The availability of quadruples that would supply the needed gradient at 4.5 К could avoid a considerable expense.
The project proposed is designed to develop superconducting quadruples based on Nb3Sn superconductor. Although practical accelerator magnets of this type have not been mass produced, recent advances in conductor technology and in the understanding and performance of Nb3Sn model accelerator-type magnets are encouraging, and lead one to believe that we could be on the threshold of a technical breakthrough. The use of Nb3Sn technology is now common in fusion devices, such as Tokomak-15, and is being assumed for the ITER fusion project.
The proposed project is very interesting from a technological point of view. It will promote development of superconductor with critical current density of more than 600 A/mm2 in a magnetic field of 12 T, at a temperature 4.2 K. It will require development of flexible high-temperature insulation, соil winding and potting techniques and thermodiffusion technology.
The specifications and requirements of the model magnet will be defined at FNAL, which has more experience in the design and operation of superconducting accelerators than any other laboratory.
The development and manufacture of the superconducting wire and cable, and thermodiffusion annealing of the cable samples and the magnet coils will be conducted at ARIIM by scientists and engineers with world-class experience in the development and creation of a new superconducting materials. They will make use of the extensive equipment already existing at their institute. Development of the quad magnetic and mechanical design, fabrication of the magnet parts, magnet assembly and tests will be conducted at IHEP, by the group of the experts that has recently developed and manufactured superconducting magnets for the 3 TeV UNK collider. The equipment used for tins work exists at the institute.
The cable fabrication will be done at USA under leadership of FNAL experts and using wire made at ARIIM.
The deliverable of the Project will be a development, fabrication and test of a superconducting quadruple magnet with high gradient and large aperture. These parameters describe a magnet, which is at, or close to the present technological limit.
Participation in the Project will allow one to save the skilled technological groups at ARIIM and IHEP and will make use of excellent and unique equipment. Successful completion of the Project will permit Fermilab to consider purchasing up to 30 full-size magnets on a contract basis. It does not guarantee such a purchase. It will give a large group of experts the opportunity to work in the new superconducting technology for many years to come. Similar quadruple magnets with high field gradient could be used in the other projects; in particular the Large Hadron Collider (LHC) the construction of which is soon to be started at CERN.