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According to this the plasma of a plasma torch can reach up to $28000$ degrees Centigrade.

How is it possible for the plasma to reach a temperature much higher than that of The Sun's surface and not completely burn and melt everything in a mile radius?

Even with the poor heat conductivity of the air this high a temperature should be more than enough to heat everything within seconds.

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    $\begingroup$ Comments are not for extended discussion; this conversation has been moved to chat. $\endgroup$
    – ACuriousMind
    Oct 19, 2020 at 21:17

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You are probably confusing "temperature," which is proportional to the log(number of available energy states), with "total energy," which depends on how many particles have a certain temperature; and then look at how quickly they can transfer that energy to neighbors.

My "go-to" demonstration of this is to put a sheet of aluminum foil in the oven, set to maybe 240 Celsius, and ask people to pull it out bare-handed. It hardly even feels "warm" to the touch. It's hot, but doesn't hold much energy. But stick your hand into a pot full of water at, say, 65 Celsius and it'll hurt. Cooler but lots more energy transferred into your skin.

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  • $\begingroup$ I believe you but have trouble grasping this. Do you mean the temperature noted in Wikipedia isn't what a super-duper-thermometer would measure about the flame but some more "potential" temperature the flame has, which doesn't directly transfer to what we feel as temperature with our skin? I am also having trouble understanding your aluminum experiment. Aluminum, being a metal, can surely be heated to a temperature that would feel as 240 Celsius if left in the oven long enough. I'm pretty sure I've touched hot sun-heated aluminum. $\endgroup$ Oct 19, 2020 at 17:21
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    $\begingroup$ @user14092802 "feeling" temperature isn't accurate. We are only good at feeling heat transfers. This is why, for example, why metal objects at room temperature "feel" colder than a book at room temperature. As this answer says, don't mix up temperature with energy. $\endgroup$ Oct 19, 2020 at 17:27
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    $\begingroup$ @user14092802 the point of using very thin aluminum in the oven is that because it has so very little mass it also cannot contain very much energy even at 240 C. When you "feel" temperature what you actually sense is the temperature of your skin - you can't detect the internal temperature of another object. So the thin metal transfers a little heat to your skin, and your skin warms up a very small amount, and that's all you feel. $\endgroup$ Oct 19, 2020 at 23:09
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the sun also in the corona has a temperature of 1000000 K, that is where the sun is mostly pure plasma. and in the plasma torch it is a very small region where you have this 28000°C, and the heat is absorbed by the nearby material to be welted.And yes it is heated in less than a second, but only at a point.

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If you wish to learn more, the technical concept is called “heat capacity”. If the heat capacity of something is low, then it can get very hot with relatively little energy, as is the case for your example.

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