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 As of September 2010, the status of the calculable capacitor project can be summarized as follows:
- The remaining precision components (lead screw and main electrode bars) have been delivered from NMIA to the BIPM, and have been successfully installed in the instrument. The four capacitor main electrodes (500 mm long, 50 mm diameter solid stainless steel bars) were manufactured at NMIA Australia using a carefully monitored hand lapping process. The finished bars show deviations from a perfect cylinder of less than 100 nm along the entire working length of 400 mm. This remarkable precision of manufacturing will allow an absolute capacitance standard with a relative uncertainty of a few parts in 109 (via the Thompson Lampard theorem of electrostatics).
- The complete instrument includes many other precision mechanical components and an interferometer is needed to measure a displacement of a moveable guard electrode. The capacitor has been fully built up to test all the critical components, alignment procedures and the functioning of the interferometer. Some key components will now be redesigned in the light of this experience (for example the spring mounts at the top of the main electrodes).
- No fundamental flaws have been found that will prevent the instrument reaching its target uncertainty of less than 1 part in 108. The alignment procedure for the main electrodes has been demonstrated to the required precision, and the interferometer behaves well (showing a mechanically very stable cavity between the moveable mirrors).
- Some further experimentation will be necessary to finalize the redesigned components, and the optical system needs further development, but the instrument is expected to be essentially complete by the end of 2010.
- 2011 will then see the concentrated work of measurement, testing of influence quantities and estimation of uncertainty components required to arrive at a value of RK.
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