1st Plenary AMT Meeting

1^st Plenary AMT Meeting at CERN – 25 March 2004

Summary of the main points discussed

·          Activity overview

NED and AMT activities are closely related and must be pursued synergically, taking care to avoid unnecessary duplication (e.g. low-field pulsed magnets are restricted to AMT). Similarly, any overlapping with US activities, which are focused on (but not by any means restricted to) quadrupoles, should be discussed in the framework of LARP CERN-US committee. The number of international meetings will be kept small to minimize travels, however interpersonal contacts are strongly encouraged. A clear commitment is expected from the top management in view of secure funding (keeping in mind that EU contributions are normally supposed to go towards networking expenses and not personnel).

·          Choice of superconductor material

Nb₃Sn emerged from the WAMS 2004 workshop as the only realistic candidate for the development of accelerator magnets with the required characteristics for the LHC upgrade (15 T, L³15m, Ƴ88mm) in the time scale foreseen. While it is possible, as Fermilab experience shows, to build high field NbTi magnets by optimizing carefully the design parameters, this material represents a weak solution since many important issues, such as integration, reliability under high thermal loads and production scaling, remain unsolved. The scientific evidence in favor of Nb₃Sn for magnets to be produced for the upgrade of the LHC interaction region, however, must be presented more strongly and clearly before funding can be allocated for this task.

·          Industry involvement

The anticipated scale of production of Nb₃Sn magnet is not sufficient, at present, to elicit a strong interest on the part of industries. To this end, it would be beneficial to study the overlap in high-performance demands with applications such as high-field NMR and MRI.

·          Cable testing facility

Existing facilities (e.g. SULTAN) do not satisfy the demanding field, power and size requirements for 1 m, 15 T Rutherford Nb₃Sn cable samples. Planned facilities for fusion cables could conceivably do double duty, however the time scale for these is unlikely to be compatible with CARE deadlines. The possibility of simultaneous use of existing fusion facilities in the short term, taking into account the financial effort necessary to make them consistent with widely different specifications, should be considered. However, the best solution for the medium- and long-term appears to be the upgrade of the FRESCA facility, which will be completely free around mid-2006 and which is already equipped with (very expensive) infrastructure and a superfluid Helium plant. While the interest of CERN users is obvious, it should be understood that FRESCA has to be proposed as a Network facility, fully open and available to all participants.

·          Material property database

A unified, cross-validated database with cryogenic material properties would be an important tool to disseminate the knowledge and guarantee consistency of calculations and design across all Network partners. Such a tool has been recently realized in the field of fusion, while nothing of the kind exists in HEP. This project shall be one of the main deliverables of AMT and should be put forward with high priority, if possible allocating a dedicated fellowship.

·          Cross-calibration of computer codes

Also this kind of effort has a precedent in the fusion community but was never undertaken in accelerators. Although it is not realistic to expect standardization of all existing codes, at least we should aim at cross-validating (and making widely known) what is currently available. Another important goal is the integration of specialized codes (e.g. for beam losses, quench propagation, magnetic field and mechanical stress calculation) to provide strongly coupled, highly detailed Finite Element models and simulations.  

·          Cable insulation

Saclay is patenting a Wind & React method making use of organic prepregs undergoing heat treatment. This method offers good performance, does not require vacuum impregnation and could be licensed at a nominal cost. A restricted workshop to merge the insulation and magnet communities will be planned in 2004. 

·          Irradiation testing

Irradiation testing is especially demanding because it must be carried out at both power and total dose levels equal to the specifications, and at cryogenic temperatures to avoid annealing. While suitable commercial facilities (e.g. RAL) are prohibitively expensive, the fusion community and Russia have accumulated a lot of expertise in this field, which should be drawn on to find alternatives.