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Fig. 4.

image

Temperature dependence of the lower cut-off energy Ec, for a selection of values of the non-thermal energy per thermal electron, uacc/ne, representative of the conditions in a relatively quiet atmosphere. A power-law index of δ = 4 was used, but any realistic value would give practically identical results. The shaded area is where the cut-off energy would be lower than the average thermal energy.

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