SPECS CCX 70, User Manual

Page: 17 / 40

13
CCX 70
V1.1 | 29 April 2016
If several instruments use the water cooling supply, the water flow rate, temperature, and pres-
sure need to be checked. In this case, water cooling for the instruments needs to be set up in a
shunt arrangement. Make sure that all instruments receive adequate cooling.
Caution!
The minimum flow rate for the XR 50 is 2.5 l/min. Do not operate the source
with a lower flow rate, as severe damage can result.
3.4 Temperature
The cooling water temperature is important for reliable operation. The recommended water
temperature range is 15–22 ºC, with a nominal temperature of 20 ºC.
You should avoid water temperatures outside this range:
Ÿ Lower temperatures can easily cause condensation on the source (depending on the dew
point), leading to flashovers of the anode HV to ground.
Ÿ Higher temperature may result in overheating of the source, leading to evaporation of the
anode or—in the worst case—a cracked anode with a water leak into the chamber.
The water temperature is displayed in the Chiller menu of the UXC 1000. You can also set the
lower and upper temperature limits in this menu.
3.5 Water Current
Figure 2 shows the principle of operation of an X-ray source. Of particular interest in this sec-
tion is the water resistance. During operation, the anode is at a potential of up to +15 kV. Due to
the finite conductivity of the anode cooling water, there is also a current that flows through the
water to ground.
Water resistance
I
F
U
F
I
W
U
A
I
A
I
E
e
-
Filament Anode
U
F
= Filament voltage
I
F
= Filament current
I
E
= Emitter current
I
A
= Anode current
I
W
= Water current
U
A
= Anode voltage
Figure 2: Operation of X-ray source
For stable operation, the water current should be in the range 2…10 mA. You can monitor the
water current in the Chiller menu of the UXC 1000.