I have a simulation program which uses cgs-units. Additionally, I defined a natural system of units:
\begin{align} \text{L} = [R], \quad \text{M} = \left[ \frac{e^2}{p^2 R^9} \right], \quad \text{T} = \left[ \frac{1}{p R^3} \right]. \end{align}
Here $R$ denotes a particle radius, $e$ is the elementary charge and $p$ describes new charged particles created due to ionization per volume and time. I now want to convert a literature value for the energy (in eV) into this natural units. First I derived the unit of the energy in this system of units:
\begin{align} E = \frac{\text{M}\,\text{L}^2}{\text{T}^2}= \frac{e^2}{p^2 R^9} R^2 p^2 R^6 = \frac{e^2}{R} \end{align}
But now I'm not sure how to convert Joule or respectively electron volt to this kind of unit. How do you derive such a conversion factor?
Regarding @J.G. answer:
I'm now distinguishing the elementary charge in CGS with an index from the one in SI. So the conversion factor for $1\text{eV}$ should be
\begin{align} \alpha&=\frac{1\text{eV}}{E} = \frac{e}{E} \frac{\text{J}}{\text{C}} = e \frac{R}{e^2_{\text{CGS}}}\, \frac{\text{J}}{\text{C}} = e \frac{4\pi \epsilon_0 R}{e^2} \, \frac{\text{J}}{\text{C}} \\ &= \frac{4\pi \cdot 8.854 \cdot 10^{-12}\,\frac{\text{As}}{\text{Vm}} \cdot 10^{-7} \,\mu\text{m}} {1.602\cdot 10^{-19}\text{C}} \, \frac{\text{J}}{\text{C}} \\ &= 69,4538 \frac{\text{J}\text{As}}{\text{C}^2\text{V}} \\ &= 69,4538 \frac{\text{J}}{\text{C} \text{V}} \\ &= 69,4538 \frac{\text{J}}{\text{C}} \frac{\text{C}}{\text{J}} \\ &= 69,4538 \end{align}
in the natural system of unit. $R$ was chosen as $0.1\,\mu\text{m}$.