The U.S. Heavy Ion Fusion program is developing superconducting focusing quadrupoles for near-term experiments and future driver accelerators. Following the fabrication and testing of several models, a baseline quadrupole design was selected and further optimized. The first prototype of the optimized design has achieved a conductor-limited gradient of 132 T/m in a 70 mm bore, with measured field harmonics within 10 parts in 10(4). In parallel, a compact focusing doublet was fabricated and tested using two of the first-generation quadrupoles. After assembly in the cryostat, both magnets reached their conductor-limited quench current. Further optimization steps are currently underway to improve the performance of the magnet system and reduce its cost. They include the fabrication and test of a new prototype quadrupole with reduced field errors as well as improvements of the cryostat design for the focusing doublet. The prototype focusing units will be installed in the HCX beamline at LBNL, to perform accelerator physics experiments and gain operational experience. Successful results in the present phase will make superconducting magnets a viable option for the next generation of integrated beam experiments. (c) 2005 Elsevier B.V. All rights reserved.

The Levitated Dipole Experiment (LDX) is a new, innovative magnetic confinement fusion experiment being designed and installed in collaboration with Columbia University at the Massachusetts Institute of Technology (MIT). The primary objective of the experiment is to investigate the possibility of steady-state, high-beta plasma confinement with near classical transport. The main component of the experiment is a levitated cryostat with a 5.7 T Nb/sub 3/Sn superconducting magnet, housed in an Inconel high pressure helium vessel. The pressure vessel is surrounded by a large thermal mass radiation shield and an outer vacuum shell, all of which are magnetically levitated inside a much larger vacuum chamber. The cryostat, now under construction is described in this paper. The cryostat keeps the magnet temperature between 5 and 10 K during 8 hours of levitated operation.

The all-du-paths structural testing criterion is one of the most discriminating of the data-flow testing criteria. Unfortunately, in the worst case, the criterion requires an intractable number of test cases. In a case study of an industrial software system, we find that the worst-case scenario is rare. Eighty percent of the subroutines require ten or fewer test cases. Only one subroutine out of 143 requires an intractable number of tests. However, the number of required test cases becomes tractable when using the all-uses criterion. This paper includes a formal specification of both the all-du-paths criterion and the software tools used to estimate a minimal number of test cases necessary to meet the criterion.

It is argued that a full set of tests should subject the model coils for the ITER (International Thermonuclear Experimental Reactor) to a minimum of 40000 operating cycles. They describe a proposal to carry out such an extended performance cyclic test where the TF (toroidal field) and CS (central solenoid) model coils would be combined into a single test arrangement and the field cycled continuously every 1 to 4 min. They propose that the TF model coils be down-sized to a noncircular shape, 2 m×3.5 m ID, and be operated as inserts in the CS model coils rather than tested in a stand-alone mode. Approximately four months of continuous cycling would be required for the life test, but it is likely that two years of elapsed time would be required to complete the tests. Near-continuous operation would also demonstrate the reliability of auxiliary cryogenic and power systems. To compensate for the loss of large coil fabrication experience with the down-sizing of the TF model coil, the authors propose that a full-scale double pancake of the ITER TF coil be fabricated from production conductor, and that it be cold tested in a prototypical `Q/A Production Test'