Centrifuge hardware modifications
It has been one of our priorities to introduce the MWA system as least invasive as possible. However, some modifications to the hosting centrifuge are inevitable.
The MWA detector requires two feedthroughs in the centrifuge's heat sink: one optical, one electric. Both are made as small as possible. The electrical feedthrough is a 21 pin LEMO connector. Plugs can be removed and re-attached from both sides – within the chamber (vacuum side) and below (ambient side). The vacuum sealing connector remains in its seat.
The optical feedthrough is mounted into a conical thread and holds four optical fibers, of which one is used. Typically, we deliver feedthroughs with two pairs of fibers, optimized for the UV-Vis and the NIR-Vis region, respectively. One fiber each is intended to be a spare. The vacuum seal needs to be replaced if fibers are broken; this is a tedious procedure requiring the drive to be removed, intended only for experts.
In order to accomodate the feedthroughs, one Peltier element has been removed so that the modified heat sink is operated with 8 rather than 9 Peltiers.
Another necessary modification is a cutout in the can within the vacuum chamber, as well as in the safety plate on the base of the can. This is necessary to allow the MWA arm to move below the rotor.
The detector arm is mounted into four existing holes in the heat sink – no additional holes were drilled. Screws and spacers were custom made, adapting the detector hardware into the existing design of the heat sink.
One last modification is a cable connection to the hall pickup electronics in the safety plate circuit board. This is necessary to collect the hall pulse generated with each rotor revolution. This is the only electric connection to the hosting centrifuge.
In summary, the MWA system is mounted into the centrifuge with four minor modifications to the centrifuge itself: a cutout in the can, two holes drilled through the heat sink, one bypassed Peltier element, and one electronical connection to the hall sensor amplifier.