Questions about tokamaks

[CroMagnon]

I write fiction purely as a hobby. Typical fantasy presentation- quests, castles, dragons, swords, sorcery, spirits, elves, etc- but like to at least try basing those things on known scientific fact. My post on the intro thread has a more thorough disclaimer, as I'd rather not start every thread by explaining it's for literary research. That said, these questions are actually brainstorming for my story's magic system; the way I understand how tokamaks work is just an inspiration. I'm no physics expert, simply an enthusiast, especially plasma physics and electromagnetism. I'll still probably fudge quite a bit to make the story work. And yes, I'm sure a lot of the info I want can be Googled, but I'm no good with the internet and I doubt Wikipedia's credibility. Any helpful facts, thought-out answers, or useful links would be appreciated. But PLEASE don't tell me to just make it up or magic it, that's a last resort for when real life can't get weird enough for the story. I wouldn't ask these questions if they didn't matter. So here goes....

 

1: What is the operating temperature of the plasma in a tokamak? If I recall correctly, Wiki says about 100 million degrees Celsius.

 

2: What substance is heated to a plasma and why is it preferred?

 

3: On the Wiki page for microwave radiation, I read that the ITER tokamak uses microwaves to heat the plasma. Why is this electromagnetic frequency preferred over perhaps infrared? And in a For Dummies nutshell, how exactly does this microwave heating thing work? Same as a microwave oven? Does whatever substance is being heated to a plasma affect which frequency is best used to heat it?

 

4: I remember reading that plasma is contained with an electromagnetic field, as the ions in the plasma make it conductive. What is the strength of the field and how much energy is required to generate it?

 

5: If some flames are considered a plasma, what flames are they? At what point are the gases ionized enough to be considered a plasma? Could any strength electromagnetic field be used to contain a flame in a manner similar to a tokamak?

 

6: How exactly is one elecromagnetic frequency converted to another? For example, ultraviolet to ultra-low frequency, or ULF to microwave or infrared? Is it something that naturally happens, a process requiring complex equipment, particularly energy-inefficient, etc?

 

I hope these questions are clear enough, and neither too confusing, complex, nor stupidly simple. Again, physics is just an interest; I truly understand very little of it. Thanks in advance for any help!

[Enthalpy]

Good idea to put tokamaks in fiction and fantasy, because, err, well.

 

Wiki is rather reliable. It contains mistakes, but others sources too, and we must live with that.

 

1: yes.

 

2: D-T, short for deuterium-tritium, because this is the only mix we can hope to use in any foreseeable future. D is available in seawater. Alas, T isn't widely available.

 

3a: I vaguely suppose that the plasma is too thin to absorb infrared well, since pictures show it almost transparent in visible light. Also, we have efficient means to make concentrated microwaves; in infrared it would need a powerful and efficient laser, which isn't easy. For instance, an IR heater like in a bathroom is colder than the plasma, hence it wouldn't heat the plasma.

 

3b: The comparison with an oven isn't too bad. You can also imagine that the microwave EM field lets the plasma's electrons wobble, and as a they collide with more speed then, it makes heat. More complicated and detailed explanations exist, sure.

 

4: The induction is strong, several tesla. It's more or less the maximum possible when the tokamak is designed, keeping in mind that a tokamak has many design constraints that prevent being optimum in every aspect.

 

5: Yes, any flame is a plasma, but at a lower temperature like 1000K instead of 100,000,000K, so very few atoms are ionized in a flame, while nearly every atom is in a tokamak's plama. Because of that, containing a flame with a magnetic field won't work, as the means of action are too scarce.

 

6: It depends, sorry... Sometimes it's trivial, for instance a stone absorbs visible sunlight and emits infrared due to its temperature. Sometimes it's a complex and inefficient technology, for instance a 146nm laser taking a room and several M$ to emit 50W. No common answer nor method exists.

[CroMagnon]

Good idea to put tokamaks in fiction and fantasy, because, err, well.

 

Wiki is rather reliable. It contains mistakes, but others sources too, and we must live with that.

 

1: yes.

 

2: D-T, short for deuterium-tritium, because this is the only mix we can hope to use in any foreseeable future. D is available in seawater. Alas, T isn't widely available.

 

3a: I vaguely suppose that the plasma is too thin to absorb infrared well, since pictures show it almost transparent in visible light. Also, we have efficient means to make concentrated microwaves; in infrared it would need a powerful and efficient laser, which isn't easy. For instance, an IR heater like in a bathroom is colder than the plasma, hence it wouldn't heat the plasma.

 

3b: The comparison with an oven isn't too bad. You can also imagine that the microwave EM field lets the plasma's electrons wobble, and as a they collide with more speed then, it makes heat. More complicated and detailed explanations exist, sure.

 

4: The induction is strong, several tesla. It's more or less the maximum possible when the tokamak is designed, keeping in mind that a tokamak has many design constraints that prevent being optimum in every aspect.

 

5: Yes, any flame is a plasma, but at a lower temperature like 1000K instead of 100,000,000K, so very few atoms are ionized in a flame, while nearly every atom is in a tokamak's plama. Because of that, containing a flame with a magnetic field won't work, as the means of action are too scarce.

 

6: It depends, sorry... Sometimes it's trivial, for instance a stone absorbs visible sunlight and emits infrared due to its temperature. Sometimes it's a complex and inefficient technology, for instance a 146nm laser taking a room and several M$ to emit 50W. No common answer nor method exists.

 

Thanks for such a thorough answer! The story won't actually have any tokamaks per se, though a similar device could be designed eventually, this is just brainstorming for pyrokinesis. I doubt any explanation would really be plausible, but that's what I'm going for and I'm exploring my options.