I. Cryogenic Coldfinger 2nd Generation

"The zeroth generation of our coldfinger had numerous problems. That's why I took over the issue and designed the first generation coldfinger. The first generation is designed to get around the current problematic coldfinger and not to fundamentally fix the origin of problem. In other words, by keeping zeroth generation design, it compromises rotational capabilities and voltage application mechanism. However, the first generation is expected to give a superior thermal performance, magnitudes of order better. The second generation unlike the first generation, however, is the real BOMB!"

It was the last summer when I started an intensive design process which lasted well over three months. The design goal I set for myself was simply "to fix everything" and have some omnipotent cryogenic sample holder for transmission experiment and electron diffraction spectroscopy. The design goals were and they still are,

1. Better thermal efficiency
2. Two pi rotational capability while maintaining voltage potential
3. Making parts as small as possible while allowing maximum working surface
4. Achieve 3 while the ease of docking in UHV chamber is not compromised
5. If possible, improve the current docking mechanism
6. Open up some degree of design freedom for potential modifications to avoid over-design of the geometry over time

The picture above at the top shows the first generation (built) and the second generation (design in progress) coldfinger side-by-side. The second generation, shown on the left, has been thermally optimized to have a minimum thermal resistance across the top surface where the sample will be mounted and the cooling rod which will be inserted into a circular slot situated on the top right side of the geometry. Since the second generation coldfinger, unlike its first generation sister, is made of a solid OHFC copper, there is no significant increase in thermal resistance due to discontinuity of solids (The first generation shown in the picture is without the coldfinger base. The three of the top seven screw holes are used to fix the geometry to another base not shown. This overcomplication of mechanism prevents efficient thermal conductivity within the geomtry).

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