ANL, Argonne
TechSource, Santa Fe
CLASSE, Ithaca
Funding: This work was supported by the U.S. Department of Energy, Office of Nuclear Physics, under Contract No. DE-AC02-06CH11357.
A new cryomodule with seven low-beta superconducting radio frequency (SRF) quarter wave niobium cavities has been designed and constructed as an energy upgrade project for the ATLAS accelerator at Argonne National Laboratory. The technology developed for this project is the basis for the next generation superconducting heavy ion accelerators. This paper will discuss the methods employed to tune the cavities eigenfrequency to match the accelerator master oscillator frequency and the development of the RF systems used to both drive the cavity and keep the cavity phase locked during operation.
IUAC, New Delhi
A 15 UD Pelletron electrostatic accelerator is in regular operation at Inter-University Accelerator Center (IUAC). It has been providing various ion beams in the energy range from a few tens of MeV to 270MeV for scheduled experiments. A superconducting linac booster module having eight niobium quarter wave resonators has been made operational for boosting the energy of the heavy ion beams from the Pelletron for experiments at higher energies. A new type of high temperature superconducting electron cyclotron resonance ion source (HTS-ECRIS) was designed, fabricated and installed. It is in regular operation as a part of an alternate high current injector (HCI) system being developed for injection of highly charged ions having higher beam current in to the superconducting linac. A radio frequency quadrupole (RFQ) accelerator is being developed to accelerate highly charged particles (A/Q ~ 6) to an energy of 180 keV/A. The beam will then be accelerated further by drift tube linacs (DTLs) to the required velocity for injection of the beams to the linac booster. Details of various developmental activities related to the heavy ion accelerators and associated systems are reported.
INFN/LNL, Legnaro
The average accelerating field of the ALPI 160 MHz sputtered QWRs has been improving with time up to reach, after the last conditioning cycle, the average accelerating field of 4.8 MV/m @ 7 W. Such value can be effectively sustained in operation due to the intrinsic mechanical stability of the sputtered cavity whose frequency is practically not influenced by fluctuations in the bath He pressure. The present average cavity performance approaches the maximum average accelerating field obtainable in the presently installed cavities, most of which were produced by replacement of Pb with Nb in the previously installed substrates. A higher average value can be obtained in ALPI replacing the less performing units; it is instead necessary to sputter on appropriately built substrates to produce QWRs which can reliably exceed 6 MV/m @7W. The cavity Q-curves, which were recently measured in ALPI, show a wide range of Q0 and Q-drop, mainly associated with the substrate characteristics, but in some cases also influenced, as discussed in the paper, by cryostat assembling procedures and by cavity production and conditioning.
IUAC, New Delhi
The facility for constructing superconducting niobium resonators indigenously was commissioned at the Inter- University Accelerator Centre in 2002. It was primarily setup to fabricate niobium quarter wave resonators for the superconducting booster linac. Starting with a single quarter wave resonator in the first phase, two completely indigenous resonators were successfully built, tested and installed in the cryomodules. Subsequently production of fifteen more resonators for the second and third modules began. Several existing resonators have been successfully reworked and restored from a variety of problems. In addition to building resonators for the in-house programs, a project to build two single spoke resonators for Project- X at Fermi Lab, USA has also been taken up. A Tesla-type single cell cavity is also being built in collaboration with RRCAT, Indore. This paper presents details of the fabrication, test results and future plans.