2

I would like to know how much (in eV) is the thermal velocity of electrons and protons in the lower solar corona?

Thank you in advance!

honeste_vivere
  • 15,592
Jokerp
  • 470
  • 2
  • 9

1 Answers1

1

The solar corona is the outermost layer of the sun's atmosphere.

The temperature of the plasma in that region, based upon iron emission lines, is in the ~1-2 million kelvin range, or ~86-172 eV [e.g., Sakurai, 2017].

During a solar flare, isolated regions can reach 10 million kelvin, or ~862 eV.

There are some efforts to determine whether Te $\neq$ Ti [e.g., Landi, 2007] (often but not always Te < Ti), but quite often people assume at least thermal equilibrium between the particle species.

I would like to know how much (in eV) is the thermal velocity of electrons and protons in the lower solar corona?

Thermal speeds are not measured in units of energy, just for clarification. I assumed you meant temperature, thus I reported temperatures. To convert to a speed, use the following: $$ \begin{align} V_{Te} & \approx 593.1 \sqrt{ T_{e} } \ km \ s^{-1} \tag{0a} \\ V_{Tp} & \approx 13.8 \sqrt{ T_{p} } \ km \ s^{-1} \tag{0b} \end{align} $$ where Te(Tp) is the electron(proton) temperature in units of eV. These approximations will give you roughly the most probable thermal speeds with units of km/s, for electrons and protons given a temperature in units of eV.

honeste_vivere
  • 15,592
  • Thank you! I wanted to say the kinetic energy of the particles (thus the eV) . But this answer is great too !Thank you again! – Jokerp Apr 02 '20 at 21:24
  • @Jokerp - The temperature in a plasma only makes sense as the mean kinetic energy in the particle species rest frame, thus it is what you were looking for. Plasmas are not in equilibrium, so the thermodynamic concept of temperature is misleading. – honeste_vivere Apr 02 '20 at 22:22