The purpose of this paper is to calculate proton energy loss straggling using a full conserving dielectric function (FCDF) for plasmas at any degeneracy. This dielectric function takes into account plasma electron-electron collision considering density, momentum, and energy conservation. When only momentum conservation law is accomplished, the FCDF reproduces the well known Mermin dielectric function, when none of the conservations laws are obeyed, the random phase approximation (RPA) is recovered. Then, the FCDF is applied for the first time to the determination of the energy loss straggling. Differences among diverse dielectric functions to determine straggling follow the same behavior for all kind of plasmas then, they do not depend on the plasma degeneracy but essentially do on the value of the collision frequency. These discrepancies can rise up to 5% between FCDF values and the Mermin ones, and 2% between the FCDF ones and RPA ones for plasma with high enough collision frequency. The similarity between FCDF and RPA results is not surprising, as all conservation laws are also considered in RPA dielectric function. The fact that FCDF and RPA give similar results and the fact that FCDF considers electron-electron collisions and RPA does not, means that latter collisions are not significant for energy loss straggling calculations.

Dielectric functions of an electron plasma are calculated for an electron gas in which number, momentum, and energy are conserved during electron-electron collisions. They are compared with others in the literature, revealing that, in general, that imposition of the conservation laws tends to make the full conserving dielectric response more similar to the random phase approximation dielectric response than without it. This is due to the fact that in the random phase approximation model all the conservation laws are also enforced. Our model is checked for other plasma degeneracies; concretely we consider partially degenerate plasmas and classical plasmas. The behaviour of the dielectric functions of these plasmas is similar to the degenerate one. Differences among dielectric functions are more significant than for the degenerate case, but it is mainly due to low relaxation time values. The most relevant issue for these plasmas is the fact that the consideration of energy conservation in the dielectric function is more important in these cases, because plasma temperature is significant.

If plasmas are considered fully ionized, the electronic stopping of a charged particle that traverses them will only be due to free electrons. This stopping can be obtained in a first view through the random phase approximation (RPA). But free electrons interact between them affecting the stopping. These interactions can be taken into account in the dielectric formalism by means of two different ways: the Mermin function or the local field corrections (LFCs). LFCs produce an enhancement in stopping before the maximum and recover the RPA values just after it. Mermin method also produces firstly a high increase at very low energies, then a small enhancement at low energies and finally decreases below RPA values before and after the maximum. Differences between the two methods are very important at very low energies and by 30% around the stopping maximum.

The purpose of the present paper is to describe the effects of electron-electron collisions on proton electronic stopping in plasmas of any degeneracy. Plasma targets are considered fully ionized so electronic stopping is only due to the free electrons. The stopping due to free electrons is obtained from an exact quantum mechanical evaluation in the random phase approximation, which takes into account the degeneracy of the target plasma. The result is compared with common classical and degenerate approximations. Differences are around 30% in some cases which can produce bigger mistakes in further energy deposition and projectile range studies. We focus our analysis on plasmas in the limit of weakly coupled plasmas then electron-electron collisions have to be considered. Differences with the same results without taking into account collisions are more than 50%.