Environmental Engineering Reference
In-Depth Information
Table 4.1
Basic fusion reactions for technology ([43], p. 27, Figure 1.7).
s
max
(barn)
a
Reaction
(MeV)
Energy peak (keV)
Q
D
þ
T
! a þ
n
17.6
5
64
D
þ
D
!
T
þ
p
4.0
0.10
1250
3
He
D
þ
D
!
þ
n
3.3
0.11
1750
D
þ
D
! a þ c
23.9
3
He
D
þ
! a þ
p
18.4
0.9
250
T
þ
T
! a þ
2n
11.3
0.16
1000
6
Li
3
He
P
þ
! a þ
4.0
0.22
1500
7
Li
P
þ
!
2
a
17.4
11
B
P
þ
!
3
a
8.7
1.2
550
10
24
cm
2
10
28
m
2
(10 f)
2
.
a) 1 barn
¼
¼
¼
Tokamak approach, we describe two small-scale demonstrations of deuterium
fusion.
The
first is based on
field ionization of deuterium gas D
2
in a compact reaction
chamber [45]. The resulting deuterons were accelerated to 80
-
115 keVand produced
(small numbers) of fusion neutrons (the second reaction in Table 4.1) as they collided
with the target, a layer of ErD
2
, a solid with a large density of deuterons. This
observation of fusion might suggest a reactor in which a solid surface of lithium or
boron is bombarded with protons froma similar eld ionization source. Such a direct
solid-state fusion reactor was discussed in 1992 by Ruggiero [46], who concluded that
useful amounts of power would not be available. The problem with this is that the
probability of fusion is low because the D ions rapidly lose energy as they hit the Er
ions, with their large numbers of orbiting electrons, in the target. Ionization of these
electrons quickly slows theD ions to the point where fusion is impossible. In contrast,
in the Tokamak DT plasma the ions have a very long mean free path.
The second demonstration of fusion on a small laboratory scale is based on
creating muonic deuterium molecular D
2
ions, which can decay by D
-
D fusion
and muon release [47], according to the 2D and 3D processes in Table 4.1. (A mu
meson, muon, or
is like an electron but 207 times more massive.) It is unlikely that
either of these methods can evolve toward useful release of energy. At the moment,
the two demonstrate only that controlled fusion, as monitored by release of neutrons,
can be achieved under modest laboratory conditions.
m
4.1
Deuterium Fusion Demonstration Based on Field Ionization
In Chapter 1, we estimated that the potential energy of two protons in contact,
U
k
C
e
2
/
r
, is about 0.6MeV, but that protons having thermal energies in the lower range of
tens of keV in the sun essentially accounted for its output of energy. As was explained
in more detail at the end of Chapter 2, the particles are able to tunnel through the
¼
