(Left) HXR spectra of the footpoint region in the simulation with δ₀ = 5, n_b = 10⁷ cm^-3 for various starting heights x₀ = 10,40,60 Mm (green, orange and blue respectively) for both purely collisional and beam and wave interactions. (Right) The fitted spectral index over 20 to 100 keV of the footpoint region as a function of electron beam starting height x₀ for purely collisional transport (beam only) and additional wave-particle interactions.