Density profile required to obtain the fits shown in Fig. 4. Density (n(z)) and local scale height (H(z)) versus height, z, above the footpoint are shown. The input parameters H_r, N_r, and a are the best-fit parameters resulting from the fitting process outlined in Fig. 4. Two alternate density models, which are derived from the alternate fits shown in Fig. 4, are given here as dashed and dotted lines. The shaded region represents the range of heights within which observations of HXR sources were made, and so densities and scale heights outside of this range are not expected to be accurate. It was assumed that the density structure of the flare plasma was approximately constant over the ~20 s rise phase of the HXRs. Vertical solid lines indicate the location of peak emission for the denoted energies, which represent the three energy bands used in this study. The values shown correspond to the first observation, where the injection spectral index is δ = 5.