Same as Figure 2, the total energy of beam (left) and tail (middle) electrons, both normalized to the initial beam energy E ₀, and the average energy of a tail electron (right), all at t = 100τ _ql against R = τ _D /τ _ql. Simulation results for various values of the beam, plasma, and density fluctuation parameters are shown. Ranges for are as in the text. For ω _pe = 1 GHz we show Gaussian fluctuations with n _b = 10 ⁵ (crosses) and n _b = 10 ⁴ (squares), power-law fluctuations with indices 5/3 and 7/3 (triangles). Finally for ω _pe = 200 MHz we show Gaussian fluctuations with n _b = 10 ³ (diamonds).