radiation pressure

Radiation pressure tend to be a weak "force" so I would question it likely used as a prime mover in compression.

However like everything else you need to run the numbers.

I suspect you run into two problems:

1) how to prevent the ablation, because the energy absorbed from the X-rays is going to heat up your material.
2) the force created by the pressure wave when the outer layer is vaporized is an order of magnitude greater than the pressure of the X-rays themselves.

Hi Mr. DrewDad
I imagine it so, lets have a relative small but complete Tokamak device with its usual closed vacuum tube. The D-T fuel is heated and compressed normally until the sure stability limit (1-2 keV) with its own magnets, and heated ohmically by driving current and by ion beams or microwaves with the tested methods, but there would be a short, let's say 5-10 mm wide free section on the vacuum tube, where the precompressed, preheated fuel could be further compressed by the help of circular (cylindrical) radiation of soft X-ray beam. The equal dispersion could be carried out by a "Hohlraum" as I learned in the case of Inertial Fusion Systems, but perhaps it is not necessary in the "first round". The necessary "final" compression for the ignition of the fusion is about 100 million atm, which - according to my calculations - attainable at about 1-2 TW (Terawatt) peak power, which is not inaccessible from laser sources, converted into X-ray radiation with a good effectivity. So, what I have imagined is a "hybrid" Tokamak, combining the advantages of the Tokamak and the inertial fuision methods leaving out the costly frosted (cryogenic) D-T pellets as target. About the ablation... the material of the tube should be a material "transparent" for the X-ray radiation, with a very low absorbing ability (thin wolfram?, quartz?)
The igniton temperature is maintained by the generated alfa particles, the output power is transported by the divertors well tested earlier. The laser source works in a pumped way of operation, so the fuel in the plasma thread has its own inertia unable to escape from the thread, so we don't have stability problems. The fresh fuel is forwarded by the help of driving current inside the Tokamak, so the burning cycles are well controllable, that was the idea which grasped me. I found in the numeric calculation on the Inertial Fusion System papers, that the necessary pressure and temperature for the ignition are appr. an order of magnitude lower than in the normal Tokamac because of the inertia of the fuel, and of the heating power of the alfa particles. There are other tricks as well to make the ignition easier i. e. electron radiation into the plasma thread by "drilling electrons" etc.
Please Mr. DrewDad, help me if you can, I would like to elaborate this idea with correct calculation for publication.
Tamás, Budapest, Hungary

You've moved past my layman's knowledge of the subject.

Excuse me, I thought you might be a physicist. I am an engineer, I am looking for a plasmaphysicist. Is it delightful to think about this problem?
Thanks
Tamás