Computer-controlled preparation of thin tungsten layers

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• 作者：Folger ; Helmut ; Hartmann ; Willi ; Klemm ; Josef ; Lommel ; Bettina ; Thalheimer ; Werner
• 关键词：Thin films ; Self-supported foils ; Tungsten
• 刊名：Nuclear Instruments and Methods in Physics Research Section A ; Accelerators ; Spectrometers ; Detectors and Associated Equipment
• 出版年：1997
• 期刊代码：41_01689002
• 类别：ph
• 出版时间：September 21, 1997
• 卷：397
• 期：1
• 页码：55-58
• 文件大小：483 K

摘要

Tungsten layers of 1-6 mg/cm² with diameters of 10 mm are needed as heavy-ion targets and as flat or domed windows for in-beam ion sources. They are prepared by a high-vacuum evaporation-deposition process carried out in a computer-controlled apparatus. The tungsten, placed in the water-cooled crucible of an electron-beam gun, is gradually heated and evaporates at about its melting point (T_m = 3643 K). The tungsten is deposited onto 9 mg/cm² copper backings which are preheated by the thermal radiation from the evaporant. The deposition rate is controlled by a quartz crystal monitor. After the high-vacuum deposition process, the copper backings are removed by selective etching and the self-supported tungsten foils are characterized by their areal mass. The features of the commercially available evaporation unit used are discussed by way of this deposition process.