Experiments to Control Atom Number and Phase-Space Density in ...
Experiments to Control Atom Number and Phase-Space Density in ...
Experiments to Control Atom Number and Phase-Space Density in ...
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7.2.4 Water-Cool<strong>in</strong>g of MOT <strong>and</strong> Feshbach Coils<br />
The Feshbach coils, the Feshbach coil H-bridge, <strong>and</strong> the MOT coils are all water-<br />
cooled <strong>to</strong> avoid overheat<strong>in</strong>g dur<strong>in</strong>g the experimental sequence. Sufficient cool<strong>in</strong>g capa-<br />
bility is provided by a heat-exchanger (Aff<strong>in</strong>ity, EWA-04AA-CE56CB). Orig<strong>in</strong>ally the<br />
heat exchanger used a valve <strong>to</strong> control the water flow of chilled university water through<br />
the heat exchanger. This provided control of the temperature of the water used for<br />
cool<strong>in</strong>g the coils. Unfortunately that valve is no longer functional. An external valve<br />
(Johnson <strong>Control</strong>s, VA-4233-6GA-24) <strong>and</strong> a thermocouple measur<strong>in</strong>g the water temper-<br />
ature of the cool<strong>in</strong>g water are therefore added <strong>to</strong> the circuit. A home-built controller<br />
box based on an Ardu<strong>in</strong>o microcontroller controls the temperature of the chilled water<br />
runn<strong>in</strong>g through the coils by adjust<strong>in</strong>g the water flow from the university water l<strong>in</strong>es.<br />
Temperature stabilization of the cool<strong>in</strong>g water is important <strong>to</strong> ensure that all coils are<br />
sufficiently cooled without caus<strong>in</strong>g condensation. The water temperature is typically set<br />
<strong>to</strong> approximately 18 ◦ C. Figure 7.24 shows the layout of the water-cool<strong>in</strong>g system.<br />
cooled<br />
University<br />
water<br />
Valve<br />
Heat exchanger<br />
Thermocouple<br />
Water lter<br />
Pump Pump Damper Damper<br />
MOT coil 1<br />
MOT coil 2<br />
Flow meter<br />
Figure 7.24: Water cool<strong>in</strong>g for the MOT coils, Feshbach coils, <strong>and</strong> the Feshbach coil<br />
H-bridge.<br />
Directly beh<strong>in</strong>d the water output of the heat exchanger a water filter is <strong>in</strong>stalled <strong>to</strong><br />
115<br />
Feshbach coil 1<br />
Feshbach coil 2<br />
H-bridge