XR 50
V3.1 | May 02, 2016
7.3
Voltages and Currents
Figure 26 shows the currents and voltages involved in generating X-rays.
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 26: The voltages and currents involved in the X-ray source
All of these parameters are displayed on the operating menu of the UXC 1000 when you start a
preset with the exception of the water current, which is shown in the chiller menu (from the
operating menu, select
Menu
then
Chiller
).
7.3.1
Anode Voltage and Current
The output voltage of the UXC 1000 is applied to the source anode. This voltage is the anode
voltage, U
A
and can be set in the range 0…15 kV.
The anode current is measured directly in the high voltage power supply as the voltage across
a shunt resistor. In the operation of the XR 50, it has two constituents:
Emission current.
Water current.
7.3.2
Emission Current
During operation, electrons are emitted from the filament and accelerated toward the anode.
An emission current (I
E
) flows from the filament through the anode to ground. The amount of
the emission current depends on the filament current (I
F
) and the acceleration (anode) voltage
(U
A
) The emission current flows through a shunt resistor to ground allowing the current meas-
urement. The emission control unit of the UXC 1000 measures the emission current and con-
trols the filament current so that a constant emission current is achieved.
7.3.3
Filament Current and Voltage
The emission control unit of the UXC 1000 supplies the filament voltage, U
F
, and the filament
current, I
F
. It is capable of powering the filament up to 10 V/ 8 A.
When the XR 50 is in standby mode, the filament current is set to a lower value. The standby cur-
rent is set so that the emission current in standby mode is around 0.1 mA. Under certain
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Summary of Contents for XR 50
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