Transport is the key issue in understanding and controlling magnetically confined plasma. Generally, in fusion plasmas, transports are mainly due to fluctuations in plasma parameters. On Madison Symmetric Torus Reversed-field Pinch, electrostatic fluctuations may be the dominant transport mechanism in improved confinement plasmas when magnetic fluctuations are suppressed. Electrostatic fluctuation driven transport can be estimated by simultaneous measurements of the fluctuating density, fluctuating potential and the wavenumber spectra. The heavy ion beam probe (HIBP) has measured fluctuations of the density and potential in PPCD plasmas at core of MST as well as one component of the wavenumber vector (k) using the 2-point technique. However, both experiments and simulations show that the measured component of k isn’t in the direction needed to calculate the particle transport. An alternative k estimate method has been developed and used in this thesis, taking advantage of Doppler shift associated with plasma rotation. Together with the measured correlation and phase between density and potential fluctuations, the electrostatic fluctuation induced particle flux has been calculated, which can account for ∼30% of the total particle flux. Furthermore, the measured k ( kρ_s ∼ 0.3) are within the range of ion temperature gradient (ITG) modes recently predicted by gyrokinetic linear stability analysis, which suggests the measured fluctuations might be ITG related. To achieve these results, the system was upgraded and a noise subtraction technique was refined resulting significantly improved signal to noise levels. In addition, operation with a velocity selector system allows for five times more accurate calculation of beam (secondary) trajectory and measurement location. Both time varying equilibrium and unstable sweep voltage have been included in the data selection and modeling.