I would like to receive comments from PLD (pulsed laser deposition) experts about a problem we are experiencing for the first time during PLD deposition. never had such problem before (we did not used argon gas previously, only oxygen)

The depositon is in argon gas atmosphere using a metallic target.

The heater is lamp type with tungsten filament.

Laser is YAG compact type. We can do the deposition without problems if the chamber is in vacuum conditions (rotary pump) and heater is at about 300 C (or any other T), BUT if we fill argon gas in the chamber, after few seconds the heater short cuts (to be precise: the "ON" swith on theh heater controller switches on "OFF" position - the electric line going to the main electric cabinet outside the lab is not affected) and experiment is ruined.

Some details 1) We opened the chamber and heater contacts are OK, are completley insulated. heater itself, or contacts, are not the problem. 2) If we raise up temperature, we stay in rotary vacuum (or even in air atmosphere, without starting the rotary) and laser hits the target, nothing happens, heater is stable for all the duration of experiment 3) BUT if we do the experiment inserting argon (200 mTorr or so, but any pressure of Ar does same effect) after vacuum pumping, with heater on, after few seconds after laser hits the target, the heater shuts down. Has someone experienced similar situation?

We believe that argon may be ionized by the laser, and the ionized gas creates a shortcut, then heater switches off. Is this scenario possible according with your experience?

Shall we use another neutral gas (nitrogen? helium?) or avoid the neutral gas at all and hit the target under vacuum without any gas?  In these experiments, we cannot use oxygen or air.

If some colleague can consider my question about argon ionization and reply me, I would immensely appreciate

If more details are needed, please ask me.

best regards Paolo Mele