Constant DC supply and 3 phase AC (in mercury rectifier) can produce a continuous arc. But can single phase AC also produce a continuous arc? Because it is written on the web that arc extinguishes at zero crossing. Also high voltage is needed to initiate arc. But what is needed to maintain the arc (high voltage or high current)?
Electronic – Can single phase AC produce a continuous electric arc
archigh voltagehigh-current
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Is it really possible to “boost” 6 V DC to above 50kV? Or even 400kV?
Of course. One common example of something similar (although not as extreme as your specs) is using 12 V in a car to make several 10s of kV to fire the spark plugs.
The same concept can be scaled up to make higher output voltages. It won't be easy to build something with that stepup ratio and output voltage yourself, but the physics is certainly possible.
Your simulation is incomplete for practical components. A function generator is mentioned as a signal source (of unknown type)...these generally have an internal source resistance close to 50 ohms, not 1 ohm. This will limit the power available - however function generators often can supply 20 V peak-to-peak with no load. A square wave source will provide slightly more power than a sine wave.
A practical inductor will have both internal resistance, and capacitance. In addition, any wire or plate you attach to its "hot" end will add capacitance.
Nevertheless, your approach to generating higher AC voltage is OK: it is possible to boost amplitude to hundreds of volts from a standard type function generator.
simulate this circuit – Schematic created using CircuitLab
The values of the inductor's parasitic components are guesses, and depend very much on the actual inductor you have available. A wire attached will also radiate a little energy away, reducing voltage.
Since impedance is high, any sparks will be feeble. A function generator should be protected by its 50 ohm internal resistance if it is of sound design.
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Best Answer
tl; dr version: With AC the arc current does drop to zero, but the plasma hangs around, so the visual arcing effect is continuous even if the arc current is not.
When the arc fires up it makes a plasma cloud - a region of ionized gases with lower resistance than air. This plasma persists for a time even during the AC zero-cross interval, allowing the arc jump once more at a lower strike voltage than it would in normal air. So the zero-current time is lessened in the presence of plasma for a given gap - so much so that your eye can hardly see it.
This plasma is why a ‘Jacob’s Ladder’ can work with ever-widening electrodes, even on single-phase AC: the heated plasma travels upward, making a lowest-impedance path for the arc to strike.
Here's a slow-motion video showing an AC-arc Jacob's ladder which clearly shows the arc extinguishing and relighting between cycles. Notice that the arc alternates sides as it re-strikes, while following the rising plasma cloud. https://www.youtube.com/watch?v=4zxGK0hoqIc
The mercury-vapor lamp uses a plasma arc to generate light, and they're almost always powered by single-phase AC. The lamp's arc absolutely fluctuates, but like the Jacob's ladder this isn't visible due to the human eye persistence of vision, plus the glowing of the still-excited plasma, and not the least of which the lowered strike voltage of the activated plasma. So we don't see flickering on this kind of lamp either, though its variation is measureable.
Unrectified 3-phase AC arcing behavior is the same as single-phase. Each phase has single-phase AC potential to neutral, ground, or either of two phases. So arcs phase-to-phase or phase-to-ground (or neutral, if used) will also have intervals of zero-current and cross-plasma re-strike. Likewise, so would a discharge lamp powered by two legs of a 3-phase feed.