8-18 Imaging Subsystem
Imaging Subsystem Components 5DX Series 3
• Focus Coil — The Focus Coil electromagnetically concentrates the electron
beam before it strikes the X-ray Target. The Focus Coil receives power from
the Focus Coil Power Supply located in the Electronics Bay of the 5DX
System. The Focus Coil Power Supply is a precision current-controlled power
source that supplies the Focus Coil with 15-20 volts dc at 1-3 amperes of
conditioned power. The Focus Coil Power Supply is set at the factory and
should not be adjusted.
• Deflection Coil — The deflection coil electromagnetically steers the electron
beam. The deflection coil is actually a pair of directional (X and Y) coils that
cause the electron beam to follow a circular path around the X-ray Target.
• X-ray Target — The X-ray Target is a thin tungsten substrate that is attached
to a base plate. As the electrons strike the X-ray Target, electrons of the
tungsten atoms are displaced causing the emission of high energy photons (X-
rays). Additional high energy X-rays are generated when the electrons collide
with the nucleus of molecules thereby abruptly decelerating and causing a
Bremsstrahlung Effect.
• Dump Ring — The dump ring is used during automatic test as a means to
quickly terminate X-ray flux. When the electron beam hits the dump ring, X-
rays are blocked. This greatly reduces the radiation dose to customer panel
reference point components. (See Figure 8-7.)
X-ray Tube Electronics
The X-ray Tube Electronics assembly contains one serial port, daisy chained
with the X-ray High Voltage (HV) Power Supply. The X-ray HV Power Supply
supplies the X-ray Tube Electronics with -160 kilovolts dc, +15 volts dc and -15
volts dc. The X-ray Tube Electronics provides filament drive control used to make
precise X-ray Tube parameter adjustments. These adjustments are accomplished
by regulating the voltage potentials applied to the X-ray Tube filaments (the
Control Grid, and the Focus Grid). The maximum electron beam current for the X-
ray Tube is factory set to 0.100 mA (±0.010mA). To keep the X-ray Tube
Electronics cool, a fan is mounted in the top of the X-ray Tube Tower. The fan
receives power from the -15 volts dc isolated supply.
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