Table C.1
Bivariate (T, v) polynomial fits for Maxwellian-averaged charge-changing and ionization cross sections for (He2+, He+, and He0) projectiles colliding with H2O vapor.
| Coefficients | Charge-changing cross sections He–H2O | Ionization cross sections He–H2O | |||||||
|---|---|---|---|---|---|---|---|---|---|
 |
 |
 |
 |
 |
 |
 |
 |
 |
|
| T(× 106 K) | 0.1− 6.4 | 0.1− 1.6 | 0.1− 6.4 | 0.1−1.6 | 0.1−6.4 | 0.1−6.4 | 0.1−6.4 | 0.1−6.4 | 0.1−6.4 |
| Degree (n, m) | (4, 4) | (4, 5) | (4, 4) | (4, 5) | (4, 4) | (4, 4) | (4, 4) | (4, 4) | (4, 4) |
| p00 | 5.634E+01 | 1.383E+03 | −9.502E-04 | 1.394E+03 | 8.597E-04 | 4.175E-01 | 4.810E+00 | 2.141E+01 | 5.216E+01 |
| p10 | 5.115E-05 | −5.115E-04 | −5.163E-10 | −4.580E-04 | −1.461E-10 | −5.627E-07 | 7.017E-06 | 1.967E-05 | 3.431E-05 |
| p01 | 1.440E-03 | −4.620E-03 | 1.831E-08 | −5.801E-03 | −1.421E-08 | 2.190E-07 | 5.522E-05 | 2.820E-04 | 5.829E-04 |
| p20 | −1.716E-12 | 1.324E-10 | 1.334E-16 | 1.167E-10 | −4.114E-18 | 1.798E-13 | −9.003E-13 | −3.032E-12 | −5.332E-12 |
| p11 | −8.517E-11 | 2.312E-09 | 4.072E-15 | 2.570E-09 | 2.078E-15 | 4.777E-12 | 7.435E-12 | −2.469E-11 | −6.996E-11 |
| p02 | 2.829E-09 | 5.499E-09 | −8.826E-14 | 1.341E-08 | 7.786E-14 | −5.953E-11 | 5.125E-10 | 6.901E-10 | 6.584E-10 |
| p30 | 3.962E-20 | −1.750E-17 | −2.320E-23 | −1.461E-17 | 2.075E-24 | −2.328E-20 | 1.592E-19 | 4.838E-19 | 7.900E-19 |
| p21 | 1.890E-18 | −4.747E-16 | 8.743E-23 | −4.766E-16 | −2.851E-23 | −5.152E-19 | −1.088E-18 | 2.333E-19 | 3.801E-18 |
| p12 | 1.859E-17 | −3.409E-15 | −1.236E-20 | −4.711E-15 | −8.113E-21 | −2.344E-18 | −2.587E-17 | 5.518E-18 | 5.026E-17 |
| p03 | −4.679E-15 | 1.131E-15 | 1.945E-20 | −1.248E-14 | −1.747E-19 | 3.069E-16 | −1.541E-16 | −8.664E-16 | −1.216E-15 |
| p40 | −3.331E-28 | 8.607E-25 | 2.098E-30 | 6.914E-25 | −8.472E-32 | 1.055E-27 | −9.403E-27 | −2.733E-26 | −4.221E-26 |
| p31 | −2.015E-26 | 4.745E-23 | −5.493E-29 | 4.394E-23 | −6.737E-30 | 4.139E-26 | 4.004E-26 | −5.024E-26 | −2.637E-25 |
| p22 | −4.579E-25 | 4.740E-22 | 8.608E-28 | 5.430E-22 | 1.719E-28 | −6.375E-26 | 7.008E-25 | 6.289E-25 | −7.978E-25 |
| p13 | 1.647E-23 | 1.909E-21 | 2.855E-26 | 3.563E-21 | 9.351E-27 | 1.438E-24 | 1.882E-23 | 6.757E-24 | −6.629E-24 |
| p04 | 1.810E-21 | −5.883E-21 | 4.557E-25 | 4.205E-21 | 1.396E-25 | −1.808E-22 | −7.139E-23 | 3.258E-22 | 5.335E-22 |
| p41 | − | −1.720E-30 | − | −1.513E-30 | − | − | − | − | − |
| p32 | − | −2.304E-29 | − | −2.339E-29 | − | − | − | − | − |
| p23 | − | −1.472E-28 | − | −1.980E-28 | − | − | − | − | − |
| p14 | − | −2.730E-28 | − | −9.401E-28 | − | − | − | − | − |
| p05 | − | 2.774E-27 | − | 3.938E-30 | − | − | − | − | − |
Notes. The fits are valid for solar wind speeds 100− 800 km s−1 and for solar wind temperatures ranging from 100 000 K to 6.4 × 106 K, unless mentioned otherwise. “E±XX” refers to × 10±XX. To obtain a better fit, the maximum temperature for the fit was reduced to 1.6 × 106 K for σ20 and σ10. All polynomial fits should be multiplied by 10−22 to scale to the final cross section. Consequently, the (n, m) polynomial model is 
with σMACS expressed in m2, T in K and v in m s−1. n is the degree of the polynomial in T, m that of the polynomial in v, and pij are the polynomial coefficients. Errors are a combination of those of the non-averaged cross sections and those of the bivariate fits. They are indicated in superscript as (a)<25%, (b) 25− 75%, (c) > 75%.
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