Results of LIA-10M accelerator investigations
There are presented basic results of experiments on the LIA-10M accelerator since its putting into operation (1994) till today. There were investigated various modes of accelerator operation and its output characteristics depending on the parameters of injected electron beam, number of connected acc...
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| Опубліковано в: : | Вопросы атомной науки и техники |
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| Дата: | 2001 |
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Національний науковий центр «Харківський фізико-технічний інститут» НАН України
2001
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| Цитувати: | Results of LIA-10M accelerator investigations / V.S. Gordeev, G.A. Myskov, V.O. Filippov, I.V. Viktorov // Вопросы атомной науки и техники. — 2001. — № 3. — С. 38-40. — Бібліогр.: 4 назв. — англ. |
Репозитарії
Digital Library of Periodicals of National Academy of Sciences of Ukraine| _version_ | 1859759214426062848 |
|---|---|
| author | Gordeev, V.S. Myskov, G.A. Filippov, V.O. Viktorov, I.V. |
| author_facet | Gordeev, V.S. Myskov, G.A. Filippov, V.O. Viktorov, I.V. |
| citation_txt | Results of LIA-10M accelerator investigations / V.S. Gordeev, G.A. Myskov, V.O. Filippov, I.V. Viktorov // Вопросы атомной науки и техники. — 2001. — № 3. — С. 38-40. — Бібліогр.: 4 назв. — англ. |
| collection | DSpace DC |
| container_title | Вопросы атомной науки и техники |
| description | There are presented basic results of experiments on the LIA-10M accelerator since its putting into operation (1994) till today. There were investigated various modes of accelerator operation and its output characteristics depending on the parameters of injected electron beam, number of connected accelerator modules, time program of inductors switch-in etc. There was obtained a large scope of experimental data that are of interest for LIA-10M accelerator practical use and for the development of new facilities of this type. The investigations that have been performed recently make it possible to considerably (half as much again) increase the output dose parameters of the accelerator as compared to the level achieved before: maximal dose (Si) and dose rate on the output flange constitute 400 Gy and 2.5.1010 Gy/s, while at a 1 meter distance from the target they are equal to 7.5 Gy and 5.108 Gy/s, respectively.
|
| first_indexed | 2025-12-02T02:48:52Z |
| format | Article |
| fulltext |
RESULTS OF LIA-10M ACCELERATOR INVESTIGATIONS
V.S. Gordeev, G.A. Myskov, V.O. Filippov, I.V. Viktorov
Russian Federal Nuclear Center – All-Russia Scientific Research
Institute of Experimental Physics (RFNC-VNIIEF)
607188, Sarov, Nizhni Novgorod region, Russia
E-mail: gordeev@expd.vniief.ru
There are presented basic results of experiments on the LIA-10M accelerator since its putting into operation (1994)
till today. There were investigated various modes of accelerator operation and its output characteristics depending
on the parameters of injected electron beam, number of connected accelerator modules, time program of inductors
switch-in etc. There was obtained a large scope of experimental data that are of interest for LIA-10M accelerator
practical use and for the development of new facilities of this type. The investigations that have been performed re-
cently make it possible to considerably (half as much again) increase the output dose parameters of the accelerator
as compared to the level achieved before: maximal dose (Si) and dose rate on the output flange constitute 400 Gy
and 2.5⋅1010 Gy/s, while at a 1 meter distance from the target they are equal to 7.5 Gy and 5⋅108 Gy/s, respectively.
PACS numbers: 29.17.+w
During the period beginning from the time of LIA-
10M [1-3] putting into operation till now there have
been made about 1800 work pulses. In the course of the
accelerator experimental development there was per-
formed a large scope of experimental investigations pur-
posed at studying the peculiarities of its operation and
aimed at achieving maximal dose parameters at the fa-
cility output. In the experiments the conditions of opti-
mal injection, acceleration and transport of electron
beam were investigated depending on its parameters
(amplitude and current pulse duration of the beam, its
diameter and injection energy), delay time of injected
beam pulse as related to the accelerating voltage pulses
of inductors and time program of inductors turn-on as
related to each other.
One of the tasks at the initial stage of researches
consisted in defining the optimal correlation between
the pulse durations of injected beam current and the ac-
celerating voltage formed by the inductors. In Fig. 1
presented is an oscillogram illustrating the shape of
voltage pulses at the output of LIA-10M inductor in the
idle mode. The inductor forms the group of pulses of al-
ternate polarity with different amplitude and duration.
To accelerate the beam there was used the second pulse
(of negative polarity) with the amplitude of 2 MV and
22 ns duration at a half-maximum. The maximal dura-
tion (FWHM) of the beam current pulse formed by the
LIA-10M injector [4] is approximately twice as large.
However, there exists the possibility of its regulation
within the limits from 20 to 40 ns through the change of
the turn-on time of the controlled pre-pulse switch in-
stalled at the output of the injector forming system.
Fig. 1. Shape of voltage pulses at LIA-10M inductor
output.
a b
c d
Fig. 2. Oscillograms of injected beam current pulses
(duration at half-maximum: a – 40 ns, b – 35 ns,
c - 30 ns, d – 25 ns).
In the experiments performed the duration of the in-
jection current pulse varied from 40 to 25 ns with a step
of ~5 ns. The obtained oscillograms of beam current
pulses injected to the accelerating channel are given in
fig. 2. At reducing the duration of pulse its shape was
changed as well as the amplitude (towards the increase
by 10-15% at pulse shortening). For each version of in-
jection there was selected the optimal time of beam cur-
rent pulse delay as related to the accelerating voltage of
inductors. The criterion of optimality consisted in get-
ting the maximal dose and dose rate of bremsstrahlung
registered at the facility output. The unique conclusion
on the fact that the best conditions for the beam acceler-
ation are achieved at approximately equal duration of
injected current and accelerating voltage pulses is the
result of the investigations performed. Thus, in case of a
shortened to 25 ns pulse of injection current the dose
(Si) of bremsstrahlung at 1 meter distance from the tar-
get was 20-30% higher than in case of a “long” (40 ns)
pulse. The advantage by dose rate was even more con-
siderable and constituted 50-70% and in separate pulses
it was close to 100%. This is conditioned by the de-
crease of bremsstrahlung pulse duration at the accelera-
tor output (Fig. 3) in case of short-pulse injection (13-15
ns instead of 15-18 ns) at simultaneous growth of dose.
The pulse of injected current can be even shorter by du-
ration than the pulse of accelerating voltage, however,
in this case the efficiency of accelerating system use de-
creases.
ВОПРОСЫ АТОМНОЙ НАУКИ И ТЕХНИКИ. 2001. №3.
Серия: Ядерно-физические исследования (38), с. 38-40.
38
mailto:gordeev@expd.vniief.ru
a
b
Fig. 3. Oscillograms of bremsstrahlung pulses corre-
sponding to 25-ns (a) and 40-ns (b) duration of injec-
tion current pulses.
Fig. 4. Dependence of bremsstrahlung dose on the
delay time of the injected current pulse as related to
the accelerating voltage of the first inductor.
In Fig. 4 presented is the dependence of
bremsstrahlung dose on the delay time of injected cur-
rent pulse as related to the accelerating voltage of the
first inductor of the accelerating system. The solid line
corresponds to the dose at 1 meter distance from the tar-
get, the dashed one – to the dose at the output flange of
the accelerator (~50 mm from the target). From the fig-
ure it is evident that maximal dose parameters are
achieved at 3-4 ns delay time of pulse injection relative
to the accelerating voltage pulse. The delay of the in-
jected current is required to compensate inductive decel-
eration of electrons on the beam front by the accelerat-
ing voltage of inductors. It should be mentioned that the
required delay time depends not only on the properties
of the accelerating structure and characteristics of accel-
erating voltage pulse but on the injection current pulse
parameters – its amplitude, duration, rise- and decay
time. In each specific case it is selected individually.
The other task solved in the course of experimental
accelerator development was to optimize time program
of accelerator modules switching as related to each oth-
er. At the velocity of electrons close to the velocity of
light in vacuum the time of their flight through a sepa-
rate inductor (axial length – 0.58 m) of the accelerating
track is equal to 1.9 ns. In the initial series of experi-
ments the time shift of turn-on for each consequent in-
ductor as related to the previous one corresponded to
this value. However, at the accelerating structure input
the velocities of electrons near the current pulse front
and slope are considerably lower than the velocity of
light while at short-pulse injection this group of elec-
trons constitutes the noticeable part of the beam. There-
fore later the program of accelerating modules turn-on
was corrected in terms of this factor.
Fig. 5. Time diagram of LIA-10M inductors turn-on.
The time diagram of LIA-10M inductors operation is
presented in Fig. 5 (solid line). The first 4 inductors
turned on in accord with the velocity of light in vacuum
(dashed line), the second group of inductors is addition-
ally shifted in time by +2.5 ns as related to the first one.
The last group of 8 inductors was delayed in run-up by
5 ns as related to the time schedule corresponding to the
velocity of light. The time shift between the two neigh-
boring inductors in each group is retained equal to
1.9 ns. Such program of inductors switching was select-
ed basing on the results of experiments in a set of ~100
work pulses of LIA-10M accelerator what provided for
getting sufficiently reliable statistics. Its realization
made it possible to additionally increase by 15-20% the
dose characteristics of the generated by the accelerator
bremsstrahlung and finally achieve the dose levels of
~300 Gy (Si) at the output flange and ~ 5 Gy - at 1 me-
ter distance from the target.
In one series of experiments there was investigated
the dependence of the dose at the accelerator output on
the number of the active accelerating modules. Here
only n=0, 4, 8, 11 and 16 of the first accelerating mod-
ules were charged and they formed the pulses of accel-
erating voltage. The case of n=0 corresponds to the op-
eration of a single injector (with no inductors turned on)
while the case of n=16 – to the operation of the acceler-
ator in a body. The chart of this dependence is given in
Fig. 6. The dose curve can be approximated by the de-
gree function
3.2
≅
N
nDD Nn , where Dn – dose at the
facility axis at n number of inductors turned on, while
DN – dose value at the same point at all N=16 accelerat-
ing modules turned on. The obtained data make it possi-
ble to predict the bremsstrahlung dose at a definite point
near the accelerator axis for the accelerator operation in
any configuration. It is of particular convenience for the
work with large-scale objects when the change of dose
load to the object through its approach or moving away
from the target does not always represent a simple task.
A considerable scope of investigations was connect-
ed with the study of LIA-10M accelerator at different-
diameter electron beam injection and acceleration. With
the increase of the number of its modules at a stage of
tuning activities it was required - for the purpose of en-
ВОПРОСЫ АТОМНОЙ НАУКИ И ТЕХНИКИ. 2001. №3.
Серия: Ядерно-физические исследования (38), с. 39-40.
39
suring stable mode of electron beam transport to the tar-
get - to gradually decrease the cathode diameter from
120 to 80 mm. For the accelerator in a body we had to
decrease as well the energy of injection from 3 to 2
MeV. It has been established later that the problem was
associated with parasitic electron emission from the
conical segment of the injector cathode what led to the
fact that the beam injected to the accelerating structure
was surrounded by a circular “aureole” of these elec-
trons. Its diameter was sufficiently large, ~160 mm, that
is comparable with the aperture of the accelerating
channel (∅200 mm). In the course of acceleration there
was observed the increase of cross dimensions of the
beam and, correspondingly, of the “aureole” surround-
ing it. Finally, it led to the electrons hit on the accelerat-
ing tubes of several last inductors what initiated electric
breakdowns on the surfaces of their insulators.
0.01
0.05
0.20
0.45
0.76
1.00
0.0
0.2
0.4
0.6
0.8
1.0
0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16
Number of turned-on inductors
D
os
e,
re
l.
un
its
Fig. 6. Relative bremsstrahlung dose change on LIA-
10M accelerator axis at different number of turned-on
accelerating units.
Table 1. Dose parameters of LIA-10M accelerator de-
pending on the cathode diameter
Parameter Cathode diameter, mm
40 60 80
Bremsstrahlung dose at
the output flange, Gy
250÷300 350÷400 300÷350
Bremsstrahlung dose at 1
meter distance from the
target , Gy
4÷5 6÷7 5÷6
Dose rate at the output
flange, Gy/s
2⋅1010 2.7⋅1010 2.3⋅1010
Dose rate at 1 meter dis-
tance from the target ,
Gy/s
3.3⋅108 4.7⋅108 4⋅108
Diameter of irradiation
spot with Dmax/Dmin=2:
at a flange, cm 5.5 9 12
at 1-meter distance
from the target, cm
50÷55
Bremsstrahlung pulse du-
ration, ns
14÷17
For the purpose of this phenomenon elimination the
configuration of the injector cathode was changed by
decreasing the axial length of its conical segment at the
corresponding increase of the cylindrical one. This had
a positive effect and made it possible to carry out the in-
vestigations of the beam injection and acceleration with
the use of cathodes of 40-80 mm diameter. We had not
managed to do it before as the diameter decrease of the
cylindrical cathode segment did not lead to the essential
change of injection parameters: cross dimensions of the
beam, its current and energy remained approximately
the same as at 80-mm diameter. The parameters of
bremsstrahlung at the output of the facility fixed in the
experiments are presented in Table 1. The best results
by dose are achieved at 60-mm cathode diameter. The
injection current and energy in this case constitute 20
kA and 2.3 MeV, respectively. In this mode there are
fixed record dose characteristics for LIA-10M. In a set
of pulses the dose at 1 meter distance from the target
was as high as 7.5 Gy (Si), while at the output flange it
achieved 400 Gy at 5⋅108 Gy/s and 2.7⋅1010 Gy/s, respec-
tively. The results obtained by a dose are ~1.5 times
higher than the levels that had been achieved before.
In the course of experimental investigations at LIA-
10M accelerator there were made noticeable strides in
increasing its output dose parameters. However, the re-
serves built in its design are not by far exhausted and
one can expect to get the dose levels ~10 Gy and higher
at 1 meter distance from the target. Both theoretical and
experimental works are being performed along this line.
REFERENCES
1. V.S.Bossamykin, V.S.Gordeev, A.I.Pavlovskii et
al. Pulsed Power Electron Accelerators with the
Forming Systems Based on Stepped Transmission
Lines // Proc. 9th Int. Conf. on High Power Parti-
cle Beams (BEAMS-92), Washington, DC. 1992.
v. 1. p. 505-510.
2. V.S.Bossamykin, V.S.Gordeev, A.I.Pavlovskii et
al. Linear Induction Accelerator LIA-10M // Proc.
9th IEEE Int. Pulsed Power Conf., Albuquerque,
NM. 1993. v. 2. p. 905-907.
3. V.S.Bossamykin, V.S.Gordeev, V.F.Basmanov et
al. Linear Induction Electron Accelerator LIA-10M
with Inductors on Stepped Lines // Problems of
Atomic Science and Technology. Issue: Nuclear-
Physics Research (31-32). 1997. # 4-5, p. 117-119
(in Russian).
4. V.S.Bossamykin, V.S.Gordeev, V.F.Basmanov et.
al. Injector of the Accelerator LIA-10M // Prob-
lems of Atomic Science and Technology. Issue: Nu-
clear-Physics Research (31-32). 1997. # 4-5. p.
120-122 (in Rusian).
ВОПРОСЫ АТОМНОЙ НАУКИ И ТЕХНИКИ. 2001. №3.
Серия: Ядерно-физические исследования (38), с. 40-40.
40
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| id | nasplib_isofts_kiev_ua-123456789-79228 |
| institution | Digital Library of Periodicals of National Academy of Sciences of Ukraine |
| issn | 1562-6016 |
| language | English |
| last_indexed | 2025-12-02T02:48:52Z |
| publishDate | 2001 |
| publisher | Національний науковий центр «Харківський фізико-технічний інститут» НАН України |
| record_format | dspace |
| spelling | Gordeev, V.S. Myskov, G.A. Filippov, V.O. Viktorov, I.V. 2015-03-30T06:40:07Z 2015-03-30T06:40:07Z 2001 Results of LIA-10M accelerator investigations / V.S. Gordeev, G.A. Myskov, V.O. Filippov, I.V. Viktorov // Вопросы атомной науки и техники. — 2001. — № 3. — С. 38-40. — Бібліогр.: 4 назв. — англ. 1562-6016 PACS numbers: 29.17.+w https://nasplib.isofts.kiev.ua/handle/123456789/79228 There are presented basic results of experiments on the LIA-10M accelerator since its putting into operation (1994) till today. There were investigated various modes of accelerator operation and its output characteristics depending on the parameters of injected electron beam, number of connected accelerator modules, time program of inductors switch-in etc. There was obtained a large scope of experimental data that are of interest for LIA-10M accelerator practical use and for the development of new facilities of this type. The investigations that have been performed recently make it possible to considerably (half as much again) increase the output dose parameters of the accelerator as compared to the level achieved before: maximal dose (Si) and dose rate on the output flange constitute 400 Gy and 2.5.1010 Gy/s, while at a 1 meter distance from the target they are equal to 7.5 Gy and 5.108 Gy/s, respectively. en Національний науковий центр «Харківський фізико-технічний інститут» НАН України Вопросы атомной науки и техники Results of LIA-10M accelerator investigations Результаты исследований ускорителя ЛИУ-10М Article published earlier |
| spellingShingle | Results of LIA-10M accelerator investigations Gordeev, V.S. Myskov, G.A. Filippov, V.O. Viktorov, I.V. |
| title | Results of LIA-10M accelerator investigations |
| title_alt | Результаты исследований ускорителя ЛИУ-10М |
| title_full | Results of LIA-10M accelerator investigations |
| title_fullStr | Results of LIA-10M accelerator investigations |
| title_full_unstemmed | Results of LIA-10M accelerator investigations |
| title_short | Results of LIA-10M accelerator investigations |
| title_sort | results of lia-10m accelerator investigations |
| url | https://nasplib.isofts.kiev.ua/handle/123456789/79228 |
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