• 5

THERMONUCLEAR FUSION26

Natural abundance of isotopes:

hydrogen                                                 nD/nH = 1-5 X 10-4

helium                                                      nHe3 /nHe4 ~ 1-3 X 10-6

lithium                                                      nLi6 / nLi7 — 0.08

Mass ratios:                        me/mD = 2.72 x 10-4 = 1/3670

(me/mD)1/2 = 1.65 X 10~2 = 1/60.6 me/mT = 1.82 x 10~4 = 1/5496 (me/mT)1/2 = 1.35 X 10~2 = 1/74.1

Absorbed radiation dose is measured in rads: 1 rad = 102 erg g—1. The curie (abbreviated Ci) is a measure of radioactivity: 1 curie = 3.7x 1010 counts sec-1.

Fusion reactions (branching ratios are correct for energies near the cross section peaks; a negative yield means the reaction is endothermic):27

►T(l.OlMeV) + p(3.02 MeV) -He3 (0.82 MeV) + n(2.45 MeV) -He4(3.5MeV) + n(14.1MeV) -He4(3.6MeV) + p(14.7MeV) -He4 + 2n + 11.3 MeV

4

(la)

D + D

50%

(lb)

 

50%

(2)

D + T

 

(3)

D + He3-

 

(4)

T + T -

 

(5a)

He3 + T-

51%

(5b)

 

43%

(5c)

P + Li6 -

6%

(6)

 

(7a)

P + Li7 -

20%

(7b)

D + Li6 -

80%

(8)

 

(9)

P + B11 -

 

(10)

n + Li6 -

 

He4 + p + n + 12.1 MeV He4(4.8 MeV) + D(9.5MeV) He5 (2.4 MeV) + p(11.9MeV) He4 (1.7 MeV) + He3(2.3MeV)

2  He4 + 17.3 MeV Be7 + n - 1.6 MeV 2He4 + 22.4 MeV

3  He4 + 8.7 MeV He4(2.1 MeV) + T(2.7MeV)

The total cross section in barns (1 barn = 10-24 cm2) as a function of E, the energy in keV of the incident particle [the first ion on the left side of Eqs. (l)-(5)], assuming the target ion at rest, can be fitted by28

aT(E)

a5 +

"(a4 - A3E)2 + l"

 

l

a2

E

"exp(AiS-1/2) _

1

 

where the Duane coefficients Aj for the principle fusion reactions are as follows:

 

D-D

D-D

D-T

D-He3

T-T

T-He3

 

(la)

(lb)

(2)

(3)

(4)

(5a-c)

ai

46.097

47.88

45.95

89.27

38.39

123.1

a2

372

482

50200

25900

448

11250

a3

4.36 x 10~4

3.08 x 10~4

1.368 X IO-2

3.98 X IO-3

1.02 x IO-3

0

a4

1.220

1.177

1.076

1.297

2.09

0

a5

0

0

409

647

0

0

Авторы: 1379 А Б В Г Д Е З И Й К Л М Н О П Р С Т У Ф Х Ц Ч Ш Щ Э Ю Я

Книги: 1908 А Б В Г Д Е З И Й К Л М Н О П Р С Т У Ф Х Ц Ч Ш Щ Э Ю Я