trufocus corporation
What does "earth ground" mean? How do I make sure my power supply and tube window is earth grounded?

TruFocus systems operate at extremely high voltages. These potentials are lethal. All equipment must be properly grounded, e.g. tube window, power supply chassy. Be certain all system components share a common EARTH ground. EARTH ground requires direct contact with the earth (the earth electrode). This can be as simple as driving a metal (usually steel or copper plated) rod or stake 6 to 10 feet into the earth, or connecting to the ground on an AC distribution panel. Proper installation procedures must be adhered to. Ground loops such as connecting unit grounds in series are NOT examples of a proper ground. Every unit is required to be individually connected to a good EARTH ground. TruFocus maintains that it is the customer's responsibility to ensure that the electronics are properly installed and grounded.

What is an "open filament"?

If the x-ray source is not producing emission current, this may be a sign that the filament is "open" or otherwise evaporated. The filament is a small metal thread that when heated to ~1000 degrees Centigrade, will allow the flow of electrons to pass through the shortest path, in vacuum, from the cathode to the anode of the tube, thus producing electrical current through the tube. This requires maintaining a stable voltage and current applied to the filament. If there is an over current, the filament will simply burn out, like a burnt out lightbulb. No filament = No photons.

What is "Leakage Current"

When applying High Voltage to an x-ray source, there should not be any emission current drawing through the tube unless programmed by the user/operator. Any current draw through the tube that is not programmed by the user/operator is "Leakage Current". There are several possible causes for this phenomenon.
1. Loss of Vacuum. If the window is punctured or pitted, or the glass envelope is broken, the tube vacuum has been compromised. This is the leading cause of leakage current. HV cannot be maintained within the tube without vacuum, as the exposed air will ionize and produce large current draw within the tube.
2. Cable and/or Packaging Failure. If the cable is punctured or a path to ground has surfaced from the HV cable wire to some exterior point or to the grounding shield of the cable, then the tube will appear to draw a large current at low kV. At this point, the cable will need to be replaced, or the tube repackaged.