The X-ray tube is an amazingly inefficient source of X-rays. Only a minute fraction of the up to 2200 watt tube power reaches the sample as X-rays, all of the rest turns into heat. That heat has to be taken away or the tube target (at least) will melt. For that purpose, a water cooling jacket surrounds the tube and directs a fast flow of water over the back of the copper target (the anode). The Haskris chiller cools the warm water coming from the tube, and sends cool water back. The heat sink is town tap water, as you can see in the plumbing diagram. Actually, the cool water flowing to the tube is not that cold, only about 68°F (20°C), because we don’t want condensation on the tube, or anywhere else around the electronics.
Additionally, both oven stages use cooling water from the Haskris chiller. When either oven is being used, water lines are connected, bypass valves are opened, and other parts are set up so the ovens will work. See the plumbing page.
Chiller maintenance is relatively simple. Any water evaporated or otherwise lost from the tank should be replaced with DI water. About once a year all the cooling water should be replaced with fresh DI water. When the water is replaced, the filter should be checked and replaced if necessary. The temperature should be set at 68°F (20°C). The outlet pressure should be set to 40 psi. Setting the outlet pressure is what controls the water flow. Low flow won’t carry away enough heat. Higher flow can cause cavitation and inefficient heat removal from behind the tube target, possibly causing it to melt. So, keep it at 40 psi. Here’s the chiller user manual.
The display panel shows the temperature. It should read about 68°F while running. Add water as necessary through the port with the big, round, black cover. The on-off switch is on the front, too, in case you didn’t notice.
This is the back of the chiller. The red hoses bring in and carry away tap water, used as the heat sink. The blue hoses carry water to and from the XRD. The RETURN valve should always be all the way open. The SUPPLY valve should be adjusted so the gauge (far left) reads 40 psi when the chiller is running. Normally this never needs to be touched.
This shows the chiller gauge, next to the blue filter housing. It should read 40 psi when the chiller is running (which it was not when this image was taken).
This is the tap water supply valve for the chiller. This valve should always be open, as shown.
