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Fusion Science and Technology
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General Kenneth Nichols and the Manhattan Project
Nichols
The Oak Ridger has published the latest in a series of articles about General Kenneth D. Nichols, the Manhattan Project, and the 1954 Atomic Energy Act. The series has been produced by Nichols’ grandniece Barbara Rogers Scollin and Oak Ridge (Tenn.) city historian David Ray Smith. Gen. Nichols (1907–2000) was the district engineer for the Manhattan Engineer District during the Manhattan Project.
As Smith and Scollin explain, Nichols “had supervision of the research and development connected with, and the design, construction, and operation of, all plants required to produce plutonium-239 and uranium-235, including the construction of the towns of Oak Ridge, Tennessee, and Richland, Washington. The responsibility of his position was massive as he oversaw a workforce of both military and civilian personnel of approximately 125,000; his Oak Ridge office became the center of the wartime atomic energy’s activities.”
E. L. Alfonso, F.-Y. Tsai, S.-H. Chen, R. Q. Gram, D. R. Harding
Fusion Science and Technology | Volume 35 | Number 2 | March 1999 | Pages 131-137
Technical Paper | doi.org/10.13182/FST99-A11963916
Articles are hosted by Taylor and Francis Online.
Hollow polyimide shells, for use as ICF targets, were fabricated by co-depositing monomer precursors from the vapor phase onto bounced spherical mandrels. The process involved two stages: first, the deposited monomers (pyromellitic dianhydride and 4,4′-oxydianiline) reacted on the mandrel surface to form polyamic acid; second, the mandrel was heated to 300°C to imidize the polyamic acid and to decompose the mandrel. During this latter process the decomposed mandrel diffused through the thermally stable coating, leaving a polyimide shell. Depositions were performed under low (∼10−3 Torr) and high (∼10−6 Torr) vacuum. Also, flat witness films of polyimide deposited on Si wafers and NaCl allowed the mechanical properties and chemical composition of the film during the heating cycle to be measured. Polyimide shells with diameters ranging from 700 to 950 μm and wall thicknesses ranging from 2 to 13 μm were produced. The shell's sphericity was greater than 99%. Burst and buckle pressure tests on these shells yielded the estimated mechanical strength properties. The elastic modulus and tensile strength were ∼15 GPa and ∼300 MPa, respectively. The permeability of D2 through polyamic acid at 25°C was 7.4 × 10−17 mol·m/m2·Pa·s and increased to 6.4 × 10−16 mol·m/m2·Pa·s at 25°C upon curing the shell to 150°C. The permeability of D2 at 25°C through vapor-deposited polyimide flat films was measured to be 240 times greater than through the as-deposited polyamic acid, and about 7 times greater than through commer ially available solution-cast Kapton.