Appendix C
Frequently used physical constants and
formulae
Physical constants (to 3 significant figures)
symbol value unit
electron mass me 9. 11 × 10 −^31 kg
proton mass mp 1. 67 × 10 −^27 kg
vacuum permeability μ 0 4 π× 10 −^7 N A−^2
vacuum permittivity ε 0 8. 85 × 10 −^12 F m−^1
speed of light c 3. 00 × 108 m s−^1
electron charge e 1. 60 × 10 −^19 C
Avogadro’s number 6. 02 × 1023 mol−^1
Boltzmann constant κ 1. 60 × 10 −^19 J eV−^1
Formulae
(all quantities in SI units, temperatures in eV,Ais ion atomic mass number)
Lengths
Debye length (p.7)
1
λ^2 D
=
∑
σ
1
λ^2 σ
whereσis over all species participating in shielding and
λσ=
√
ε 0 κTσ
n 0 σqσ^2
=7. 4 × 103
√
Tσ
n (^0) σ
m
Electron Larmor radius (p.234)
rLe=
√
κTe/me
|ωce|
=2. 4 × 10 −^6
√
Te
B
m
Ion Larmor radius (p.234)
rLi=
√
κTi/mi
|ωci|
=1. 0 × 10 −^4
√
ATi
B
√
Z
m
whereAis atomic mass andZis ion charge.
Electron collisionless skin depth (p.145)
c
ωpe
=
5. 3 × 106
√
ne
m