Collisional enhancement of low-frequency density fluctuations in a weakly collisional electron-ion plasma

In this Letter, we give closed-form solutions for the dielectric function and the electron density fluctuation spectrum in a weakly-collisional electron-ion plasma in thermodynamic equilibrium by solving the linearized Balescu-Lenard-Poisson kinetic equations. When the collisionless and collisional formulae for the fluctuation spectra are compared at long wavelengths, we find that electron-ion collisions are dominant and enhance the fluctuations for {ω} near zero and near the ion-acoustic wave frequency.