1. Limited time only! Sign up for a free 30min personal tutor trial with Chegg Tutors
    Dismiss Notice
Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

Homework Help: Reaction Rate of a Solar Fusion

  1. Apr 25, 2012 #1
    1. The problem statement, all variables and given/known data
    Find the reaction rate of a star purely of Hydrogen at temperature of 15MK, density of 150gm/cm^3, most of the reactions take place at R0=0.25R. Each reaction released energy of 25MeV

    2. Relevant equations
    This is the part I'm lacking. I've got the number of protons in the sun calculated by;
    VolSun = (4/3)*pi*(0.25R)^3
    Divided that by molar mass of Hydrogen (1) and left with number of moles of Hydrogen, thus Proton in the sun at its core.

    3. The attempt at a solution

    So from there, I went to ORNL and got the reaction rate data for H1(P,E+NU)H2 reaction
    at 15MK which is about RDensity = 50*10^-20 (cm^3*moles^-1*s^-1)

    Now, I need to find <σv> which is the reaction rate.

    I tried using <σv> = RDensity * NH(Number of moles of Hydrogen) / Volume
    Which cancels out all the units and leaves me with s^-1

    But when I take that number, multiply by 1.6*10^-19 to account going from MeV to Joules and calculate the power and thus, flux, it comes out to be a very small number which makes me feel like I'm missing something big here.
  2. jcsd
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook

Can you offer guidance or do you also need help?
Draft saved Draft deleted