Uploaded April 2026 | Updated September 2026, 3 weeks ago
This turned into a fun set of low-pressure air experiments in a vacuum chamber. Initially the plan was to reproduces a Victorian experiment known as Gassiot’s Cascade or fountain. This requires a partial vacuum and a high voltage applied through it. The trick is to place a uranium glass vessel of some kind in the path of the discharge. The plasma can then be seen to spill, like water, over the vessel. Being made of uranium glass the UV content of the air discharge produces UV light which fluoresces the glass.
There are a number of different arrangements shown in this video for effect. Dealing with high voltages and as the vacuum is around the ‘Paschen’ minimum I had a few problems with feed-in connectors. Wire feed-ins tended to break down and I resorted to using an open-ended neon tubing with an electrode to connect into the chamber. This also failed eventually with electrical stress at 20kV.
Later an LC oscillator is also placed into the vacuum as an experiment. This generate strong fields from a low voltage supply, so easy to connect up into the vacuum. It was interesting to see the plasma develop around the coil and capacitor where the field was strongest. The pressure is adjusted to determine the field peak is at the capacitor terminal between it and the coil. It was surprising the circuit survived as the plasma covered the whole circuit and I suspected may have be able to damage the MOSFET driver, visible on the heat sink.
You might spot a ferrite magnet appears in some set-ups. This was an AI suggestion but in practice it had little observable effect in on the plasma in general.
Content:
00:00 – Introduction
00:47 - First run plasma fountain.
01:42 - Low pressure run.
02:04 – Cascade arrangement
03:37 – Neon tube feed-in arrangement.
04:37 – LC oscillator in low pressure.
04:48 – Images captured from the experiments.
05:15 – outro
This video was edited and uploaded on off-grid solar 😊
This turned into a fun set of low-pressure air experiments in a vacuum chamber. Initially the plan was to reproduces a Victorian experiment known as Gassiot’s Cascade or fountain. This requires a partial vacuum and a high voltage applied through it. The trick is to place a uranium glass vessel of some kind in the path of the discharge. The plasma can then be seen to spill, like water, over the vessel. Being made of uranium glass the UV content of the air discharge produces UV light which fluoresces the glass.
There are a number of different arrangements shown in this video for effect. Dealing with high voltages and as the vacuum is around the ‘Paschen’ minimum I had a few problems with feed-in connectors. Wire feed-ins tended to break down and I resorted to using an open-ended neon tubing with an electrode to connect into the chamber. This also failed eventually with electrical stress at 20kV.
Later an LC oscillator is also placed into the vacuum as an experiment. This generate strong fields from a low voltage supply, so easy to connect up into the vacuum. It was interesting to see the plasma develop around the coil and capacitor where the field was strongest. The pressure is adjusted to determine the field peak is at the capacitor terminal between it and the coil. It was surprising the circuit survived as the plasma covered the whole circuit and I suspected may have be able to damage the MOSFET driver, visible on the heat sink.
You might spot a ferrite magnet appears in some set-ups. This was an AI suggestion but in practice it had little observable effect in on the plasma in general.
Content:
00:00 – Introduction
00:47 - First run plasma fountain.
01:42 - Low pressure run.
02:04 – Cascade arrangement
03:37 – Neon tube feed-in arrangement.
04:37 – LC oscillator in low pressure.
04:48 – Images captured from the experiments.
05:15 – outro
This video was edited and uploaded on off-grid solar 😊
