Does Radiant Energy, such as that from a DC high volts discharge through a spark gap be more contained and flow forward in a series circuit in Vacuum chamber better than in open air ,- as per dissipation? Tesla tested Hairpin circuit and dual magnets fields across the gap.

 

Arcs in a vacuum have a different mechanism to arcs in air. In air, the air itself is a conductive medium, even if it starts with a fairly high resistance. Once the breakdown voltage of the air is exceeded, a much lower resistance connection is made, consisting of ionized air (see: lightning). This means while striking an arc in air requires a relatively high voltage, maintaining that arc requires much less.

In a vacuum, the various air-related mechanisms for creating and maintaining an arc aren't operating. The arc can still form by a process called field electron emission but the voltages required are much higher. The breakdown voltage of air is quite variable due to things like humidity but a general case would be about 3000V/mm while the breakdown for vacuum would be on the order of 15000V/mm.

As stated earlier, once the arc is established, the ionized air provides a very low resistance path. For comparison, and keeping in mind the variability of "air", in a typical case of dry air, the resistance before ionization would be ~10¹¹ Ω•m. Once that ionized path is established (the arc), the resistance drops to ≤100Ω, and could be as low as <1Ω.

On the other hand, the arc in a vacuum takes much higher voltage to initiate but once established has a similar resistance to the ionized air arc. Nonetheless because initiating and sustaining an arc are two different things, an arc in a vacuum is more prone to extinguishing than one in air.

While establishing an arc requires a high voltage, sustaining one requires current. There is a critical threshold for current below which the arc will collapse. Though the required current to sustain arc is similar in each case (like the resistance of an established arc) the vacuum-arc is dependent on field emission which is sensitive to things like surface changes on the electrodes which can introduce resistance separately from the gap.

The availability of free electrons in the air-arc's plasma reduces the degradation of the electrodes in that case, not being present in the vacuum-arc the electrons of the electrodes are stripped off, additionally with not air to conduct the intense heat, the electrodes dissipate a lot more of it than in the case of air, which further degrades them, increasing resistance and dropping current to below the critical value.

 

Yours is a very thorough and scholarly answer, Y!

But the question that the TS asked appears to be about containing the actual radiant energy, I. E. light and heat.

Let’s hope the TS clarifies exactly what he meant.

 

Yours is a very thorough and scholarly answer, Y!

Who needs AI when we got @Ya’akov?

 

Probably the radiant energy from a spark in a vacuum may be greater at a distance because there is no air to absorb the heat of the arc. BUT the arc in a vacuum might be hotter.
Containing the energy in either case is a challenge. I suggest reading about the means of preventing arc-flash injuries as a useful source of practical information. Or reading the post from "Y" for the detailed technical aspects.