Index of content:
Volume 79, Issue 3, March 2008
We describe the design, construction, and performance of three generations of superconducting Ioffe magnetic traps. The first two are low current traps, built from four racetrack shaped quadrupolecoils and two solenoid assemblies. Coils are wet wound with multifilament NbTi superconducting wires embedded in epoxy matrices. The magnet bore diameters are 51 and with identical trap depths of at their operating currents and at . A third trap uses a high current accelerator-type quadrupolemagnet and two low current solenoids. This trap has a bore diameter of and tested trap depth of . Both low current traps show signs of excessive training. The high current hybrid trap, on the other hand, exhibits good training behavior and is amenable to quench protection.
- THERMOMETRY; THERMAL DIFFUSIVITY; ACOUSTIC; PHOTOTHERMAL AND PHOTOACOUSTIC
A facility for characterizing the steady-state and dynamic thermal performance of microelectromechanical system thermal switches79(2008); http://dx.doi.org/10.1063/1.2894147View Description Hide Description
A facility to characterize microelectromechanical system(MEMS) thermal switches by measuring two pertinent figures of merit is described. The two figures of merit measured are the ratio of thermal resistance of the switch in the off and on states, , and the time required to switch from the off to the on state, . The facility consists of two pieces of equipment. A guard-heated calorimeter is used to measure heat transfer across the thermal switch under steady-state conditions. Measuring heat transfer across a thermal switch in both the off and on states then gives the thermal resistance ratio . A thin-film radial heat-flux sensor is used to measure heat transfer across the thermal switch under dynamic conditions. Measuring heat transfer across a thermal switch as the switch changes from the off to the on state gives the thermal switching time . The test facilities enable the control of the applied force on the thermal switch when the thermal switch is on, the thickness of the gas gap when the thermal switch is off, and the gas species and pressure in the thermal switch gas gap. The thermal performance of two MEMS thermal switches employing two different thermal contact materials, a polished silicon surface and an array of liquid-metal microdroplets, is characterized and compared.