X-Ray Control Grid Voltage

[sixtimesseven]

Does anyone know what typical X-Ray tube control grid voltages are?

I have the datasheet for my Microfocus X-Ray tube (60kV, 1A, 50W) and it has grid control. However, no mention on the specific voltages. Does anyone know some typical values? I've seen some schematics with up to -10kV, that would be a real pain to supply.

[Wolfram]

For similarly sized dental X-ray tubes, the focus voltage tends to be in the -600 - -800 V range.

If you feel like experimenting, you can apply a variable voltage and see how the tube behaves. If you apply the maximum filament current and anode voltage, then you know the focus voltage is too negative if you don't get the rated anode current. You can also observe the focal spot with a lead pinhole and adjust the focus voltage to get the rated size. Beware that you might be able to focus the beam to a finer spot than the tube was designed for, resulting in excessive anode power density.

Edit: found some info specific to your tube, see the attachment. It looks like your focal spot is in the first category, so the actual voltage doesn't matter much. You could possibly just tie it to the cathode through a resistor in case you want CW output. Source: https://www.yumpu.com/en/document/read/3917835/produktkatalog-pdf-66-mb-petrick-gmbh . Here's some additional data on a similar tube to yours as well: https://www.yumpu.com/en/document/read/3918040/1titel-112g6-epsd-petrick-gmbh

[sixtimesseven]

For similarly sized dental X-ray tubes, the focus voltage tends to be in the -600 - -800 V range.

If you feel like experimenting, you can apply a variable voltage and see how the tube behaves. If you apply the maximum filament current and anode voltage, then you know the focus voltage is too negative if you don't get the rated anode current. You can also observe the focal spot with a lead pinhole and adjust the focus voltage to get the rated size. Beware that you might be able to focus the beam to a finer spot than the tube was designed for, resulting in excessive anode power density.

Edit: found some info specific to your tube, see the attachment. It looks like your focal spot is in the first category, so the actual voltage doesn't matter much. You could possibly just tie it to the cathode through a resistor in case you want CW output. Source: https://www.yumpu.com/en/document/read/3917835/produktkatalog-pdf-66-mb-petrick-gmbh . Here's some additional data on a similar tube to yours as well: https://www.yumpu.com/en/document/read/3918040/1titel-112g6-epsd-petrick-gmbh

Looks good. So far it worked even with the grid disconnected.
My idea was to be able to turn of the tube to a.) limit x ray emission even though I have a pretty good lead box I still don't just want to pump it out and b.) limit heating of the focal spot when not in use c.) would be to be able to adjust something inside the box but I'm not certain I trust it fully since loss of negative voltage would turn it on again.

As far as I understand the grid control is usually used to get a fast shutter to do xray "video". Might be fun as well.