Grounding a HV PSU

[Neukyhm]

Hi everyone, I'm trying to build a PSU for an x-ray tube. I have already built and tested the HV part of the circuit and it works, but the problem is that I'm not very confident about grounding everything. I have to do it because the PSU of the filament is a XL4015 module bought on eBay, so it's not an isolated PSU.

However, the HV PSU that outputs 5kV is isolated, I made the transformer myself and I used epoxy as insulation, also the tube and voltage multiplier will be submerged in dielectric oil, so in theory if I do the grounding as presented in the picture, I should have no problem, but since the voltage is high and so is the frequency, I don't know if it's a good idea to connect one leg of the 5kV transformer to the (-) of arduino and ground them all.

[PartialDischarge]

X ray tubes have both poles isolated, and the filament voltage is referred to the cathode voltage.

[Neukyhm]

X ray tubes have both poles isolated, and the filament voltage is referred to the cathode voltage.

I contacted the tube manufacturer and they told me that I can ground the cathode 

[Neukyhm]

Here you have the datasheet of the manufacturer's tube PSU (see page 2)

The connections including ground is similar to my schematic.

Edit: if you take a look to the filament regulator, it seems that it only uses a voltage regulator, wich of course it's not isolated, so it seems that they just ground the cathode and nothing more 

[PartialDischarge]

Yes it seems that is the case. Those modules are for a monoblock, where you keep the tube and the electronics in the same oil tank, close together. Given your setup you will have no other option than to ground one pole of the hv multiplier...

[Neukyhm]

Given your setup you will have no other option than to ground one pole of the hv multiplier...

I know that. What I don't know is if something will blow up because of grounding the transformer and electronics all together.

[crazyguy]

X ray tubes have both poles isolated, and the filament voltage is referred to the cathode voltage.

when the tube is in operation there is tube current (mA) flow through anode to cathode

[Neukyhm]

X ray tubes have both poles isolated, and the filament voltage is referred to the cathode voltage.

when the tube is in operation there is tube current (mA) flow through anode to cathode

Of course. You can build an isolated PSU for the filament and then yo don't really need to ground anything, just connect the cathode of the HV source to the filament, that is connected to the isolated filament PSU. But my filament PSU is not isolated so I have to ground it 

The problem is that I have never done this before although I have some experience with HV sources, but I have never tried to ground one leg of an isolated high voltage transformer and the (-) of the electronics.