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Jon_Beveryman t1_j0tmfhb wrote

Reply to comment by Graekaris in How do X-rays “compress” a nuclear fusion pellet? by i_owe_them13

No. Radiation pressure is the pressure exerted by the radiation itself. The ablation pressure is a material response to the radiation heating.

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Graekaris t1_j0tpvtb wrote

I see. In this application, is the radiation pressure comparable in significance to the ablation pressure or is it negligible?

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Jon_Beveryman t1_j0u3bff wrote

In this application the radiation pressure is pretty minimal yeah. I haven't seen numbers for it myself, but in some other settings where you care about direct radiation pressure & ablation pressure, you usually discard the radiation pressure term entirely unless you are very close to the source or it's an incredibly potent source. For instance, in Teller-Ulam type thermonuclear bombs, the radiation pressure from the fission stage is assumed to provide virtually all of the implosion pressure for the fusion stage [going by unclassified sources only ofc, e.g Winterberg "The Physical Principles of Thermonuclear Explosive Devices"].

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nicuramar t1_j0u7rb3 wrote

The ablation pressure is much higher, making the radiation pressure mostly or entirely irrelevant.

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