Some values don't make sense

[Earl of Plasma]

I’m trying my best to understand this process of fusion so I have some Questions.

First temperature. PPL are talking about several hundred milj kelvin acheaved in experiments. Other have problems to reach even 100 milj Kelvin. Just with electrodes as it seems? For exemple a Tokamak use current and radio waves just to reach 100 milj degrees. How is that possibly? How do they do?

Magnetic field. PPL are talking about giga Gauss in the magnetic field of the plasma. 1 giga Gauss is about 100 000 Tesla. 100 Tesla is pretty much and is hard to achieve for long time. How is that possibly?

[zapkitty]

Earl of Plasma wrote: I’m trying my best to understand this process of fusion so I have some Questions.

Welcome to the Focus Fusion Society forums!

Earl of Plasma wrote: “First temperature. PPL are talking about several hundred milj kelvin acheaved in experiments. Other have problems to reach even 100 milj Kelvin. Just with electrodes as it seems? For exemple a Tokamak use current and radio waves just to reach 100 milj degrees. How is that possibly? How do they do?

Size is the key… or lack of it 🙂

LPP (Lawrenceville Plasma Physics) achieved the confinement of ions with energies in excess of 100 keV (100,000 electron volts) which is the equivalent of a temperature of over 1 billion degrees Celsius. They did this in a device called a dense plasma focus… and the plasmoid where this occurred was only a few hundred microns across and lasted only for a few microseconds.

But that was enough to achieve the desired temperatures and confinement times for boron-hydrogen fusion and that’s what matters. Now LPP is working on increasing the density of their plasmoids.

ITER, on the other hand… well, although ITER only needs to reach a temperature of 100 million degrees to fuse its deuterium-tritium fuel its tokamak design has to try to heat a volume of plasma of 840 cubic meters to that temperature for about 300-500 seconds at a time… and that’s proven to be quite a challenge for them.

Earl of Plasma wrote: Magnetic field. PPL are talking about giga Gauss in the magnetic field of the plasma. 1 giga Gauss is about 100 000 Tesla. 100 Tesla is pretty much and is hard to achieve for long time. How is that possibly?

Same way the temperatures are achieved: in a very small space for a very short time.

Rather than trying to fight the natural instabilities of the process the Focus Fusion design takes advantage of them and lets them run their course.

And LPP and Focus Fusion advocates are not the only ones to have noticed that smaller and faster might be a better route to fusion. Indeed, quite a few alternative non-tokamak fusion designs are now under development and are seeking funding.

And yet President Obama’s new budget proposal once again cuts domestic fusion research funding and transfers it to ITER…

[Earl of Plasma]

Thank you for that thorow answers.

As I know it could be easier to transfer electrical energy from a broad contact area and short distance to the plasma or easier to achieve high current. If you then can keep the voltage as high as before, then short distance is good for transfer more heat.

When it comes to the magnetic field I’m more puzzled. Physics law says B = n*I*k, k is a konstant around 2*10(raised-7) in vacuum and air etc, n number of laps, because the plasma wind up like coil. That would mean that a greater distance gives higher magnetic field, since there are room for more laps in the longer coil.

A stronger magnetic field means a denser plasmoid, but how about time? Does the strength of the magnetic field affect the time the plasmoid exist? Longer time is also favorable. But I don’t have a clue if and what connection there is between time of the plasmoid and the strength of the magnetic field. Some who knows? Could there be a optimal value for the strength of the magnetic field.

To me it seems as the magnetic field gets what it gets? If size and current is decided to reach high temperatures, then there is not much room to affect the magnetic field itself.

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