Two beam induction accelerator for generation of neutrons and gamma radiation
A new scheme of a proton or electron accelerator with a pre-buncher of a driving electron beam and an accelerator of main and driving beams is presented.
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| Дата: | 2001 |
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| Формат: | Стаття |
| Мова: | English |
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Національний науковий центр «Харківський фізико-технічний інститут» НАН України
2001
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| Назва видання: | Вопросы атомной науки и техники |
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| Цитувати: | Two beam induction accelerator for generation of neutrons and gamma radiation / G.V. Dolbilov // Вопросы атомной науки и техники. — 2001. — № 1. — С. 128-129. — Бібліогр.: 7 назв. — англ. |
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irk-123456789-785302015-03-19T03:02:44Z Two beam induction accelerator for generation of neutrons and gamma radiation Dolbilov, G.V. Theory and technics of particle acceleration A new scheme of a proton or electron accelerator with a pre-buncher of a driving electron beam and an accelerator of main and driving beams is presented. 2001 Article Two beam induction accelerator for generation of neutrons and gamma radiation / G.V. Dolbilov // Вопросы атомной науки и техники. — 2001. — № 1. — С. 128-129. — Бібліогр.: 7 назв. — англ. 1562-6016 PACS: 84.40.Cb. http://dspace.nbuv.gov.ua/handle/123456789/78530 en Вопросы атомной науки и техники Національний науковий центр «Харківський фізико-технічний інститут» НАН України |
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Digital Library of Periodicals of National Academy of Sciences of Ukraine |
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DSpace DC |
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English |
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Theory and technics of particle acceleration Theory and technics of particle acceleration |
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Theory and technics of particle acceleration Theory and technics of particle acceleration Dolbilov, G.V. Two beam induction accelerator for generation of neutrons and gamma radiation Вопросы атомной науки и техники |
| description |
A new scheme of a proton or electron accelerator with a pre-buncher of a driving electron beam and an accelerator of main and driving beams is presented. |
| format |
Article |
| author |
Dolbilov, G.V. |
| author_facet |
Dolbilov, G.V. |
| author_sort |
Dolbilov, G.V. |
| title |
Two beam induction accelerator for generation of neutrons and gamma radiation |
| title_short |
Two beam induction accelerator for generation of neutrons and gamma radiation |
| title_full |
Two beam induction accelerator for generation of neutrons and gamma radiation |
| title_fullStr |
Two beam induction accelerator for generation of neutrons and gamma radiation |
| title_full_unstemmed |
Two beam induction accelerator for generation of neutrons and gamma radiation |
| title_sort |
two beam induction accelerator for generation of neutrons and gamma radiation |
| publisher |
Національний науковий центр «Харківський фізико-технічний інститут» НАН України |
| publishDate |
2001 |
| topic_facet |
Theory and technics of particle acceleration |
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http://dspace.nbuv.gov.ua/handle/123456789/78530 |
| citation_txt |
Two beam induction accelerator for generation of neutrons and gamma radiation / G.V. Dolbilov // Вопросы атомной науки и техники. — 2001. — № 1. — С. 128-129. — Бібліогр.: 7 назв. — англ. |
| series |
Вопросы атомной науки и техники |
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AT dolbilovgv twobeaminductionacceleratorforgenerationofneutronsandgammaradiation |
| first_indexed |
2025-07-06T02:35:54Z |
| last_indexed |
2025-07-06T02:35:54Z |
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1836863303440138240 |
| fulltext |
TWO BEAM INDUCTION ACCELERATOR
FOR GENERATION OF NEUTRONS AND GAMMA RADIATION
G.V. Dolbilov
Joint Institute for Nuclear Research, Dubna, Russia
A new scheme of a proton or electron accelerator with a pre-buncher of a driving electron beam and an accelera-
tor of main and driving beams is presented.
PACS: 84.40.Cb.
1. INTRODUCTION
Two projects of the electron-positron collider, CLIC
at CERN and NLC at SLAC, and collective proton ac-
celerator at Kharkov PTI assume to use the two beam
method of acceleration [1,2,3]. In the both collider
projects the high-energy main beam and the driving
electron beam are accelerated in different accelerators.
The RF power is generated by the driving e-beam when
it passes special electrodynamic structures. Then this
power is fed to the accelerating section of the main ac-
celerator.
The driving e-beam can be used to excite the main
accelerator cavities directly without the excitation of the
electrodynamic structure in the driving channel. The
driving and main beam pass one the same structure,
which bunches the driving beam and accelerates the
main beam (of protons or electrons). The particles of the
main beam are accelerated wherein the accelerating
electric fields are excited. Seeing the one mode regime
of the accelerator-buncher structure can be realized all
parasitic modes might be suppressed [4] including
modes of beam-beam instability. Therewith, if an accel-
eration of the driving electrons by external field is used,
the efficiency of the conversion of their kinetic energy
into the energy of the main particles can be close to 1.
The accelerated driving beam allows generating the
very high RF power, which is inaccessible now for mod-
ern powerful klystrons. Future accelerators will require
such a level of the RF power, which is limited by output
and input windows and mode transformers of the RF
sources and the main accelerating modules. Such units
are absent in the proposed scheme of the two beam ac-
celerator.
2. DESIGN OF THE ACCELERATOR D
A scheme of a two beam accelerator for a generation
of neutrons and gamma radiation is shown on Fig. 1.
Particles of the main and driving beam move in opposite
directions. An electron gun produces a driving beam.
The driving electron beam is pre-bunched by e-buncher.
To decrease an oscillation amplitude of the driving elec-
tron bunches the longitudinal dimension of this bunches
have to be matched with the structure of the accelerator-
buncher [5]. The dimensions of bunches have to be
close to the equilibrium dimensions in the accelerator-
buncher structure. The equilibrium bunch dimensions
are determined by amplitude of the RF field excited by
the driving beam and a value of the detuning of the ac-
celerator-buncher cavities relative to the buncher fre-
quency ξ=2Q0 ∆f /f , Q0 being the quality factor of the
unloaded cavities.
Fig. 1. Scheme of the two beam accelerator with the
excited by an electron beam copper cavities
Energy loss, which driving electron beam puts out to
excite the main beam loaded cavities, is recovered dur-
ing its acceleration in an induction electric field of the
accelerating-bunching modules. The required induction
field is far less than the accelerating field because the
phase of the induced voltage of the cavities is close to π
/2 [6].
E E
E
ind d= =
+
cos ,ϕ
ξ1 2 ξ>>1,
where φ πd ≅ 2 is a locking phase of the driving elec-
trons. So a low gradient induction accelerator allows one
to produce a high accelerating gradient for the main
beam.
Synchronism of the main beam particles and the ex-
cited field take place when a structure period of the ac-
celerator-buncher is equal to ([5,6])
L k d m= +− − −λ β β( )1 1 1 ,
where k is integer, λ - wave length, β d and β m - rela-
tive velocity of the driving and main particles.
An average accelerating gradient for the main beam
depends on an intensity of the driving beam I d , a quali-
ty factor Q and a shunt impedance R of the loaded by
main beam cavities, a relative detuning of the cavities ξ
and a number of cavities per meter.
For example, the average accelerating gradient of a
two beam induction linac with cylindrical cavities is
equal to ([5,7])
E
Id=
−
+
⋅ ⋅
1
1 2
0η
ξ
ρ
π δ
Ψ ,
128 PROBLEMS OF ATOMIC SCIENCE AND TECHNOLOGY. 2001, № 1.
Series: Nuclear Physics Investigations (37), p. 128-129.
Fig. 2. Scheme of the two beam induction linac. e:
1-RF cavity, 2-drift tube, 3-RF absorbing insertion, 4-
ceramic tube, 5-induction core, 6-focusing system
where ρ µ ε π0 0 0 120= = is the wave-forming resis-
tance of free space, δ − skin-layer , η − efficiency of
the energy conversion from the driving electron beam
into the main beam and
Ψ = + +− − −( )β β
π
d m
h
L j
1 1
0
12
,
h − accelerating gap, j0=2.4 is the first root of the Bessel
function J0.
Maximal accelerating gradient of the two beam ac-
celerator is defined by a shunt impedance of unloaded
cavities and achieved at a small value of the main beam.
But the efficiency of the energy conversion is minimal in
this case because the more energy of the excited field
goes to expense in a wall of cavities. At a high value of
the main beam current the efficiency grows but more in-
tensive driving beam is required to keep the high accel-
erating gradient. Herewith there are not any more over-
voltages in the RF mode transformers, vacuum windows
and other RF transmission units.
The counter-propagating main beam is produced by
an electron or proton gun and a pre-accelerator if the
main beam is the proton beam. To reduce the relative
value of the energy loss in the cavities of the accelera-
tor-buncher and increase the efficiency of the beam en-
ergy conversion the average current of the main beam
should be increased up to:
I
I
m
d=
+
η
ξ1
2
At such current of the main beam the efficiency of the
beam-beam energy conversion will be equal to the cho-
sen value of η [5,7]. The utilized driving beam is de-
bunched and recuperated to increase a total efficiency of
the two beam accelerator.
A scheme of the accelerating-bunching module is
shown on Fig. 2. An electrodynamic structure of the
module contains a row of RF cavities 1 and drift tubes 2
with RF absorbing insertions 3. To avoid excitation of
parasitic modes of oscillation, the technique of distribu-
tion suppression of parasitic waves is used [4]. Together
with the parasitic modes suppression, the resistive inser-
tions distribute an electric voltage of the induction mod-
ule. The electrodynamic structure is installed inside a
ceramic accelerating tube of the induction section.
The main and driving beams are focused by a mag-
netic field of permanent magnets 6. The focusing of the
main proton beam is increased by a space charge of the
driving electron beam. The repetition rate of the focus-
ing pulses of the counter-propagation electron bunches
is much higher than the frequency of transverse oscilla-
tion of the protons and proton focusing is determined by
average current of the driving beam I d . The proton os-
cillation frequency in the potential well of the electron
beam with current I d and radius rd is equal to [6]:
ϖ
π
ρ
p
d
dc
r
e I
Mc
=
1
2
0
2
Equilibrium radius of the proton beam with emittance
ε p is equal to:
r
r Mc
e Ip
p p d
d
2
2
0
2=
ε β
π
π
ρ
Intensity of the driving and main beams determines
the accelerating gradient for the main beam, the efficien-
cy of the driving beam – main beam energy conversion
and the amplification of the main accelerating gradient
as compared with the induction system gradient. For ex-
ample, to produce the main accelerating gradient
equaled 50 MeV/m in accelerating-bunching module
with induction gradient equaled 1 MeV/m, at 70% effi-
ciency of the beam-beam energy conversion ( . )η = 0 7 ,
the ~300 A driving beam current and ~4 A main beam
current are required. At emittance ε = ⋅100mm mrad
the proton beam equilibrium radius will be equal to
r rp p d≈ 01. β [r (m)].
REFERENCES
1. The NLC Design Group, “New Scheme of Two Beam
Accelerator Driver Based on the Relativistic Klystron”, in
Zero-Order Design Report for Next Linear Collider,
LBNL-5424, SLAC-474, UCRL-ID-124161, UC-414
(1996).
2. Technical Publication Department Stanford Univer-
sity “International Linear Collider Technical Review
Committee”, Stanford, USA, 1995.
3. N.A. Khizhnyak, A.G. Limar. Status of the
Kharkov’s Linear Collective Accelerator. Proc. Int.
Conf. ADTT and A, Kalmar, Sweden, 1996, p. 1087
4. G.V. Dolbilov et al.Concept of a Wide Aperture
Klystron with Absorbing Drift Tubes for a Linear
Collider // Nuclear Instruments and Methods in
Physics Research, 1996, v. A, 383, p. 318-324.
5. G.V. Dolbilov, “Two Beam Induction Linear Collid-
er”, Proc. of the 7th European Particles Accelerator
Conf. (26-30 June), 2000, Vienna, Austria, p. 904
6. G.V. Dolbilov “High Current Linacs at JINR and Per-
spective of Their Application for acceleration of Ions”,
AIP Conf. Proc. 480, “Space Charge Beam Physics for
Heavy Ion Fusion”, Sainta, Japan, 1998, p. 85-98.
7. G.V. Dolbilov. Two Beam Accelerator for Elec-
tronuclear Industry // Problems of Atomic Science
and Technology, 2000, N2 (36), p. 108-110.
129
REFERENCES
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