What is the difference between solar proton flux and solar proton density?

Solar protons are part of the solar wind.

Solar Proton Flux refers to the number of solar protons passing through a unit area per unit time. It is usually measured in units like protons per square centimeter per second (protons/cm²/s). Solar proton flux is a measure of the flow of protons from the sun.

Solar Proton Density is the concentration of solar protons in a given volume of space. It is usually measured in units like protons per cubic centimeter (protons/cm³). Solar proton density indicates how many protons are present in a specific volume.

In summary, flux measures the flow of particles through an area, while density measures the concentration of particles in a volume.