Challenges, capabilities and collaboration

Mike Tartaglia

Michael Tartaglia, deputy head of the Magnet Systems Department in the Technical Division, wrote this column.

Two of the most interesting and exciting aspects of working in Fermilab’s Technical Division are the large number and the diversity of advanced projects we have under development. These projects are intrinsically challenging from a technical-requirements standpoint, which reflects the ambitious demands of the Intensity and Energy Frontier machines. For each of many projects competing for our resources, there is also usually a challenge to deliver results on an aggressive schedule. Since other institutions around the United States and the world are engaged in various aspects of this work to develop new approaches and technologies, collaboration has become a very effective way to enhance the pace, spread the expertise and share the benefits.

A recent example illustrates how this has led to rapid progress in developing magnets to focus and steer beam within a superconducting radio-frequency cryomodule, the basic building block of a modern high-intensity linear accelerator. Motivated by discussions focused on building a proton driver and a proposed International Linear Collider, TD engineers designed superconducting magnets for such projects as early as 2005. The requirements for the ILC main-linac focusing magnets presented the greatest challenge; this design was the most interesting to develop, and it also is useful for other machines like ASTA and a future high-intensity proton accelerator at Fermilab. These cryomodules need a high-strength quadrupole magnet of short length, modest field uniformity and very stable magnetic axis over a wide range of operating strengths. An ultra-clean space within the SRF beam tube must be maintained.

Our KEK colleagues in Japan suggested splitting the Fermilab design into halves for clamping around the pre-cleaned beam tube. The coils are then cooled by thermal conduction to a cold pipe rather than immersing the magnet in a complicated liquid-helium vessel. In concert with Japanese industry, we prepared and assembled our magnet into a cryogenic test stand to assess the performance. Preliminary tests were made at KEK and then continued here, where versatile magnet protection and precise measurement systems were quickly configured to create a new test area.

Preliminary results indicate that this magnet meets ILC requirements! Now, two years after Fermilab tests began, we are about to learn how to install and operate a new magnet of this design in the first ILC-type cryomodule at KEK while we prepare for the next test in our new facility.