SIGNIFICANT EVENTS - On-Going Flight Program
02/16/01

STEP Team Produces Unique Aerogel Samples

The production of aerogel for the containment of liquid helium in a 200-liter dewar has reached the point of manufacturing prototypical samples. Since the microscopic structure of silica aerogel is composed of a highly porous open-cell network of minute silica fibers, aerogel is an excellent candidate for the containment of liquid systems. In the spring of 2000, 14-cm annular cylinders were made and tested as a first step in developing the aerogel required. After inserting these annular cylinders into a metal sleeve, the aerogel was immersed in liquid helium to demonstrate that the helium would fill the pore structure of the aerogel. Since the ingress and egress of liquid helium is crucial to the project, the testing showed that aerogel was a viable material for liquid helium entrainment.

Due to the limited size of the available aerogel production facility, 25-cm annular cylinders were the largest single annular units that could be successfully processed. In late 2000 and early 2001, rounded trapezoidal blocks were produced having a volume of approximately 2.5 liters each. Six of these aerogel blocks have been produced and assembled to form an annular structure 45 cm in diameter and 10 cm in height (see photo below). This annulus is, in fact, prototypical of a portion of the current design for the flight aerogel system.

Aerogel

Several meetings have taken place between those involved in the STEP aerogel initiative from Stanford, JPL, and the Lockheed Advanced Technology Center. Testing and developmental work is about to begin on the specific design of the aerogel assembly. Ultimately, it is projected that 56 blocks will be manufactured and joined to form a structure that will fill the interior of the STEP flight dewar. The production of relatively large, precisely molded geometrical shapes had not been previously demonstrated prior to this work. Thus, not only is the utilization of aerogel for the containment of liquid helium tides a novel feature of the STEP project, but also the aerogel being developed is unique in its scale and geometric precision.



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