Can one move from Inertial to Magnetic Confinement?

[clope023]

Hello all, my question is related to graduate school topics and future postdoc possiblities.
I'm a double major in electrical engineering and physics and have been doing plasma physics research as an undergraduate for roughly the last two years, with the last summer I played a part in installing a diagnostic onto the MAST tokamak at the Culham Centre for Fusion Energy. My current advisor says it's not necessarily a good thing to marry yourself to the research you did in undergrad, but I'm very much interested in doing fusion plasma research in graduate school and as a career. Though the option to stay and continue my research that I'm doing now at my ugrad institution is open, I'm very much interested in going elsewhere for graduate school. Assuming I got into a grad school that focused on inertial as opposed to magnetic confinement fusion. My question would be how feasible is it to move from inertial/laser confinement to a magnetic/tokamak sort of focus from grad school to post doc (assuming I went to my reach school in question)? I'm interested in diagnostics, plasma instabilities, as well as plasma-material interactions if that plays a part in your advice. Thanks for any and all opinions on the matter.

 

[Hercuflea]

I don't think it would be much of a problem, especially since you are already focused on the plasma aspect.If all you worked on was laser physics and didn't know anything about plasmas that might be a problem, but sounds like that is not the case :)

 

[the_wolfman]

People can and do make the switch, but If you want a career in magnetic fusion, study magnetic fusion. If you want a career in inertial fusion study inertial fusion.

The two fields are really very different. A critical aspect of magnetic fusion is the magnetic field. The shape and quality of the magnetic field influences everything from stability, to transport, to even the plasma-material interface. In inertial confinement fusion, the magnetic field is tiny compared the dynamical pressure. As a result most ICF research ignores any and all dynamics related to the magnetic field.

Similarly shock dynamics are a critical aspect of inertial confinement. Yet they play little role in conventional magnetic fusion confinement concepts.

As a final comment on the difference between the two. A critical parameter in plasma physics is the plasma parameter, which is the number of particles in a Debye Sphere. In order for something to be considered a plasma you need a large plasma parameter, and thus a lot of particles in a Debye Sphere. At IFC conditions relevant to ignition, the number of particles in a Debye Sphere is less than one, thus the plasma parameter is small. So in ICF at ignition, you don't actually have a classical plasma. The technical name for this new state is "strongly-coupled plasma," but this is misleading, and you arguably have a totally different state of matter.

 

[middlephysics]

People can and do make the switch, but If you want a career in magnetic fusion, study magnetic fusion. If you want a career in inertial fusion study inertial fusion.

The two fields are really very different. A critical aspect of magnetic fusion is the magnetic field. The shape and quality of the magnetic field influences everything from stability, to transport, to even the plasma-material interface. In inertial confinement fusion, the magnetic field is tiny compared the dynamical pressure. As a result most ICF research ignores any and all dynamics related to the magnetic field.

Similarly shock dynamics are a critical aspect of inertial confinement. Yet they play little role in conventional magnetic fusion confinement concepts.

As a final comment on the difference between the two. A critical parameter in plasma physics is the plasma parameter, which is the number of particles in a Debye Sphere. In order for something to be considered a plasma you need a large plasma parameter, and thus a lot of particles in a Debye Sphere. At IFC conditions relevant to ignition, the number of particles in a Debye Sphere is less than one, thus the plasma parameter is small. So in ICF at ignition, you don't actually have a classical plasma. The technical name for this new state is "strongly-coupled plasma," but this is misleading, and you arguably have a totally different state of matter.

The low plasma parameter is due to the small debye length for ICF?

 

[the_wolfman]

The low plasma parameter is due to the small debye length for ICF?

Yes. The Debye length scales as $n^{-1/2}$ and the plasma parameter scales as $n\lambda_D^3$ which also scales as $n^{-1/2}$. Both Debye length and the plasma parameter are small in ICF due to the large number densities.