Document

Internal electrostatic confinement fusion
(慣性静電閉じ込めによる核融合)
論文紹介
by 白鳥昂太郎
Paper
Institute
Institute of Advanced Energy, Kyoto University
Prof. Kiyoshi Yoshikawa's Research Group
京都大学エネルギー理工学研究所エネルギー
生成研究部門粒子エネルギー研究分野
吉川潔研究室
http://www.iae.kyotou.ac.jp/beam/index_j.html
Brief introduction of Internal electrostatic
confinement fusion : IECF
IECF is the scheme of injecting the
ions and electrons towards the
spherical center, trapping both species
in the electrostatic self-field and giving
rise to fusion in the dense core.
(Fusion mechanism is not completely
understood.)
For effective production of neutron,
multi-well potential is needed.
Energy of neutron
d+d→3He+n : 2.5 MeV
d+t→4He+n : 14.1 MeV
(d+3He→4He+p : 14.7 MeV)
Background
The concept of IECF is conceived in 1950s.
The first purpose is to investigate the room
temperature fusion system (for power source ?).
→Not realistic…
→Latest type, input 100W ⇔Output by fusion
1μW
But…
IECF is a good neutron source.
→ Investigation is continued.
The Machine
Intensity of neutron
d+d→3He+n : 2.5 MeV → 5×106 n/s
(High voltage and ion current are unknown)
Advantage of IECF compared with
neutron source (example 252Cf)
Mono-energetic spectrum
No decreasing by particle decay
Easy to operate
Energy spectrum of neutron from Cf
Able to use proton source O.I. Batenkov et al., INDC(NDS)-146,(1983)
252
(d+3He→4He+p : 14.7 MeV)
Good application 
Purpose of this paper
To measure ion current dependency of
neutron yield (N∝I2) for investigating IEFC
mechanism
To explain mechanism by theoretical
calculation for offering the technical
advantages
↑
 The structure of internal potential is unknown. →
fusion mechanism
 Information for developing the technical progress :
To optimize high voltage, current and to develop
cooling system →Technical advantages
Ion current dependency of neutron yield
Calculation by multi-well potential:
N∝I2 (I=ion current)
⇔Experimental result: scales linearly I
Limitation of high voltage and current are
70kV and 15 mA, respectively.
Not to exceed the threshold for multi-well
potential
Perveance : I(mA)/V1.5(kV) > 2.2
Re-experiment by sufficient condition
by using pulse current
I2 dependency over the threshold was
confirmed.
Result of theoretical calculation
To construct the program by multiwell potential and to simulate the
dependency of ion current
N∝I3 dependency exists in the
high current region.
→Increased ion current make
multi-well potential unstable and
this unstably increase the density of
central region.
⇒The experiment to confirm this
dependency in the high current
region should be performed.
Result of theoretical calculation
To construct the program by multiwell potential and to simulate the
dependency of ion current
N∝I3 dependency exists in the
high current region.
→Increased ion current make
multi-well potential unstable and
this unstably increase the density of
central region.
⇒The experiment to confirm this
dependency in the high current
region should be performed.
Conclusion
The dependency of ion current (N∝I2) by
multi-well potential is confirmed.
There may be the dependency N∝I3 in the
high ion current region.
→ The experiment should be performed.
Progress after this experiment
 Multi-well potential
was first measured by
the laser-induced
fluorescence method.
 To increase the
nuetron intensity of DD reaction
→ 2×108 n/s
Future plan
Improvement of ion source
Glow discharge ＋ Magnetron ion source
Intensity of neutron will be increased by
one-order (108→109 n/s).
Application
Examples
Mine sweeper 
Development with 7 organizations
They plan to operate this machine in Afghanistan.
Why neutron source ?
 It is very difficult to distinguish
mine from other metals by metal
detector.
→ mine/metals = 1/1000 under the
ground
→The plastic and ceramic mine
cannot be detected.
 The composition of TNT is
known.
→By measuring γ ray from TNT
reacted with neutron and back
scattered neutron by proton in
TNT, we will be able to
distinguish mine from other
metals.
What detect ?
 γ ray from neutron capture :
1H(n,γ), 14N(n,γ)
 Energy
1H(n,γ) : 2.22 MeV
14N(n,γ) : 10.8 MeV
 CsI, NaI, BGO for detection
 10.8 MeV → Detected by
BGO multi compton gamma
camera
BGO gamma compton camera
Expected performance
(1m×1m field, 20cm depth, 30
g mine)
～106 n/cm2/s
Efficiency 99.9%
Miss identify 40% @ 10 min
Other method
回転する鎖で地面をひたすら叩いて、
片っ端から爆発させる
Summary
Present performance of IECF : 2×108 n/s.
IECF will be able to be used for several
applications by adjusting neutron intensity.
Mine sweeper with IECF is planned.

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