Operation of the 400-750kV pulse voltage multi-cascade discriminator
The multi-cascade discriminator (МD) of the amplitude of pulsed 400-750kV voltage is an important part of the pulse high-voltage generator at the highcurrent linac injector of the Moscow meson factory [1]. It was invented and designed at the Efremov Institute of Electrophysical Apparature (Leningrad...
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| Опубліковано в: : | Вопросы атомной науки и техники |
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| Дата: | 1999 |
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Національний науковий центр «Харківський фізико-технічний інститут» НАН України
1999
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| Цитувати: | Operation of the 400-750kV pulse voltage multi-cascade discriminator / V.N. Zubetz, V.I. Derbilov, S.K. Esin, V.S. Klenov, E.S. Nikulin, O.T. Frolov, V.P. Yakushev // Вопросы атомной науки и техники. — 1999. — № 4. — С. 38-39. — Бібліогр.: 3 назв. — англ. |
Репозитарії
Digital Library of Periodicals of National Academy of Sciences of Ukraine| _version_ | 1860042167169318912 |
|---|---|
| author | Zubetz, V.N. Derbilov, V.I. Esin, S.K. Klenov, V.S. Nikulin, E.S. Frolov, O.T. Yakushev, V.P. |
| author_facet | Zubetz, V.N. Derbilov, V.I. Esin, S.K. Klenov, V.S. Nikulin, E.S. Frolov, O.T. Yakushev, V.P. |
| citation_txt | Operation of the 400-750kV pulse voltage multi-cascade discriminator / V.N. Zubetz, V.I. Derbilov, S.K. Esin, V.S. Klenov, E.S. Nikulin, O.T. Frolov, V.P. Yakushev // Вопросы атомной науки и техники. — 1999. — № 4. — С. 38-39. — Бібліогр.: 3 назв. — англ. |
| collection | DSpace DC |
| container_title | Вопросы атомной науки и техники |
| description | The multi-cascade discriminator (МD) of the amplitude of pulsed 400-750kV voltage is an important part of the pulse high-voltage generator at the highcurrent linac injector of the Moscow meson factory [1]. It was invented and designed at the Efremov Institute of Electrophysical Apparature (Leningrad). It was partially tested at the factory [2] and successfully ran at 1 Hz repetition rate [3] in the adjusting mode of the accelerator. However the transition to 50Hz repetition rate gave rise to certain drawbacks, such as the current overloading of the inductivities, breakdown of the diodes and insufficient voltage. Analytical and experimental researches were conducted, and the required changes were made on their basis. These changes allowed the discriminator to operate with high reliability. The main results are set forth in this report.
|
| first_indexed | 2025-12-07T16:56:37Z |
| format | Article |
| fulltext |
OPERATION OF THE 400-750KV PULSE VOLTAGE MULTI-CASCADE
DISCRIMINATOR
V.N.Zubetz, V.I.Derbilov, S.K.Esin, V.S.Klenov, E.S.Nikulin, O.T.Frolov, V.P.Yakushev
Institute for Nuclear Research, RAS, Moscow
1. INTRODUCTION
The multi-cascade discriminator (МD) of the
amplitude of pulsed 400-750kV voltage is an important
part of the pulse high-voltage generator at the high-
current linac injector of the Moscow meson factory [1].
It was invented and designed at the Efremov Institute of
Electrophysical Apparature (Leningrad). It was partially
tested at the factory [2] and successfully ran at 1 Hz
repetition rate [3] in the adjusting mode of the
accelerator. However the transition to 50Hz repetition
rate gave rise to certain drawbacks, such as the current
overloading of the inductivities, breakdown of the
diodes and insufficient voltage. Analytical and
experimental researches were conducted, and the
required changes were made on their basis. These
changes allowed the discriminator to operate with high
reliability. The main results are set forth in this report.
2. ANALYSIS OF THE MULTI-CASCADE
DISCRIMINATOR OPERATION
The periodic process is considered when at the
end of each period all inductivity currents and the
capacitors voltages revert to their values in the
beginning of the period. The period is divided into 2
parts; in the first part currents and voltages grow, in the
second part they revert to original values.
2.1. DISCRIMINATION OF PULSED VOLTAGE
The principal scheme of the device for limitation
of positive voltage impulses is shown in fig. 1а. When
the applied voltage exceeds the sum of С1÷Сn voltages
and drop of voltages on all diodes V1÷Vn, these diodes
conduct the Ii pulse current, which slightly increases the
charges of capacities during the time of the pulse ti by δ
Ui=Iiti/Ci. The sum voltage instability is equal to their
sum on all capacitors, i.e. δU=nIiti/C, if capacities are
identical. During the impulse the voltage which
approximately repeats the general impulse form is
applied to each inductivity; its magnitude is
proportional to this cascade capacity voltage. As a
result, j-inductivity current will be augmented by
Ij=U0kujtiki/Lj,
where U0 is reference voltage of the discriminator, kuj is
coefficient which demonstrates how many times the j-
capacity voltage is less than U0; ki=1+(tb+te)/ti/2 allows
for a role of fore and back fronts in the inductivity
current increasing, Lj is inductivity of the corresponding
cascade (see Fig. 2а).
Fig. 1.
2.2 DISCHARGE OF CAPACITIES BETWEEN
IMPULSES
Between impulses all capacitors return charges in
a reference supply source when average current In=nIitif
running, where f is pulse repetition rate (see Fig. 1b).
The numeration of cascades starts from the output. Let
us consider the first cascade. The inductivity current
should be diminished by magnitude I1=U0ku1tiki/L1; the
negative voltage U2-U1+Ur1+R1il1 (where U2 and U1-
voltage on capacities С2 and С1 accordingly, Ur1 -
voltage drop on the diode Vr1, R - ohmic resistance of
the inductivity wiring, il1 - momental value of a current
in L1) is applied to the inductivity. For МD parameters
it is possible to assume with satisfactory accuracy that R
is a small value, the current is changing linearly during
t1 when the charge Q=Iiti passes through the inductivity.
Hence δU1=U2-U1=I1L1/t1-Ur1 and Q=I1t1/2.
Having made necessary transformings, we get
t1=2L1Ii/(U0kiku1), δU1=(U0kiku1)2ti/(2IiL1)-Ur1
For the second cascade it is necessary to take into
account, that there pass charge 2Q, hence
t2=4L2Ii/(U0kiku2), δU2=(U0kiku2)2ti/(4IiL2)-Ur2
and for j-cascade, accordingly, charge jQ and
tj=j2LjIi/(U0kikuj), δUj=(U0kikuj)2ti/(j2IiLj)-Urj-RIj/2,
if tj < 1/f. The diagrams of currents are shown in Fig. 2b
and 2c.
It is necessary to take into account that δUj will
ВОПРОСЫ АТОМНОЙ НАУКИ И ТЕХНИКИ. 1999. № 4.
Серия: Ядерно-физические исследования (35), с. 38-39.
38
be in all previous cascades, i.e., with coefficient j in a
total MD voltage loss.
If tj > 1/f, then δUj + Urj + RImj gets such value,
that during 1/f-ti the j-inductivity current has changed
by Ij; here the average current Iaj=jQf. Then, neglecting
ti in comparison with 1/f, we receive
δUj=U0tifkikuj-Urj-RjjQf
Fig. 2.
Now it is possible to write the expression for a
total loss of MD voltage, if k - the number of the
cascade, after which tj > 1/f,
j=k
∆U=Σj((U0kikuj)2ti/(j2IiLj)-Urj-RjIaj)+
j=1
j=n
+Σj(U0tifkikuj-Urj-RIaj)
j=k+1
The j-capacity voltage (let j < k) is determined as
m=n m=n
Uj=U0-Σ(δUm)=U0kuj=U0-Σ(U0tifkikum-RmmQf)-
m=k
m=j m=k+1
-Σ((U0kikum)2ti/(m2IiLm)-RmIam)+Ur(n+1-j)
m=j
Let us consider the important case, when the
parameters L, R, Ur for all cascades are identical. Then,
accepting the symbols: ∆Ur=∆U/(nU0), ∆
UL=U0tiki
2/(2IiL), t0=2LIi/(U0ki), and accordingly
tj=t0(j/kuj, I0=U0tiki/L, Ij=I0kuj, δUj=U0∆ULkuj
2/j-Ur or δ
Uj=U0kfkuj-Ur-RIaj, where kf=tikif, we receive the loss
of voltage in relative units
j=k j=n
∆Ur=(∆UL /n)Σkuj
2+(kf/n)Σ(jkuj)-(Ur/U0)(n+1)-
j=1 j=k+1
j=k j=n
-(R/(U0n)) (Σ(jIj/2) +Qf Σj2)
j=1 j=k+1
and the j-capacity voltage, j < k (relative units)
m=n m=k
Uj/U0=kuj=1-kfΣkum-∆ULΣ(kum
2/m)+Ur(n+1-j)+
m=k+1 m=j
m=k
+(R/U0) (Qf (n-k) + I0/2 Σkum)
m=j
The simplest cases are of certain interest:
1). A repetition rate is small, for all cascades tj < 1/f,
Iaj=Ij/2, and let kuj~1.0, then
∆Ur = ∆UL-(Ur/U0)(n+1)-RI0(n+1)/(4U0)
m=n
kuj=1-∆ULΣ(1/m)+(Ur/U0)(n+1-j)+(RI0/2U0)(n+1-j)
m=j
For ideal МD, when Ur and R are neglectedly
small, the loss of voltage is determined by the first
member. It does not depend on cascade number and is
inversely proportional to Ii and L; the condition of
acceptable loss determines the value of inductivity. The
diode voltage drop and ohmic resistance, on the
contrary, equalize the voltages on capacities and
moderate the total loss of voltage. With the growth of
cascade number this tendency has a stronger effect.
2). The repetition rate is large, t1 > 1/f, let kuj~kuf and
Iaj=jQf, then
j=n
∆Ur=kf(n+1)/2kuf-(Ur/U0)(n+1)-(RQf/(U0n))Σj2
j=1
kuj=1-kfkuf(n+1-j)+(Ur/U0)(n+1-j)+(R/U0)Qf(n+1-j)
Here for ideal МD the loss of voltage grows
linearly with the number of cascades and does not
depend on the value of inductivity. The influence of
diodes has the same nature, the influence of resistance
has a stronger effect as the cascade number grows.
In order to take into account precisely all the
parameters of the multi-cascade discriminator, the PC
computation code for currents and voltages in all
correlated cascades was developed. The fastest
convergence of results is received for the initial state,
when the capacitor voltages equal zero, and with each
impulse they receive a charge Iiti. The formed voltages
were observed after approximately 70 impulses, i.e. a
few seconds later. The MD experimental values agree
well with the computer calculations.
3. THE PROTON INJECTOR DISCRIMINATOR
For the discriminator considered the parameters
have the following values: U0=25kV, n=32, L=10H,
Ur=60V, R=50Ohm, Ii=2,5A, ki=1,5, ti=85mcsec. Then
the main magnitudes for 50Hz repetition rate are equal:
∆UL=9,56%, t0=0,00133s; I0=0,319A; kf=0,64%.
ВОПРОСЫ АТОМНОЙ НАУКИ И ТЕХНИКИ. 1999. № 4.
Серия: Ядерно-физические исследования (35), с. 38-39.
38
Table 1.
f (Hz) 10 25 50 100
U2
(kV)
Precisely
approx.
20,9
21,5
20,9 20,3
20,6
18,2
18,3
U1
(kV)
Precisely
approx.
19,3
20,2
19,3
20,1
18,8
19,4
17,0
17,5
U
(kV)
Precisely
approx.
768
768
768
765
749
742
691
695
In Table 1 the results of calculations made in
accordance with the mentioned formulas and by the
computer are compared. It can be seen that assumptions
made when deducing the formulas are justified.
In Table 2 the dependence of output voltage
(relative units derived from nU0) on L value and
voltages on the first two capacities for two modes is
shown when f=10 and f=100Hz; the other parameters
are invariable.
Table 2
L (H) 2 5 10 20 50 100
Ur
(rel. units)
10Hz
100Hz
.746
.746
.884
.839
.951
.855
.992
.860 .862 .862
U2 (kV) 10Hz
100Hz
10.4
10.4
16.6
15.8
21.5
18.3
23.3
18.6 18.7 18.8
U1 (kV) 10Hz
100Hz
8.4
8.4
14.5
13.9
20.2
17.5
22.3
18.0 18.5 18.6
4. INDUCTIVITY
For multi-cascade discriminators, when current
in last inductivity does not drop to 0, currents in first
and last inductivities differ n times, where n is cascade
number. Therefore inductivity wiring requirements are
completely different. The last inductivity current is the
greatest one, it is equal
Ian=nIitif.
Active current in first inductivity is much less because
current continues only during t1 time, and so there is no
need to have such large wire cross-section as for the last
inductivity. All inductivity wirings were changed for the
new ones in proton injector discriminator.
If, as it is for injector, inductivities have
magnetic cores it is possible to rise their values for the
first cascades by decreasing air gaps of cores. This
action will reduce voltage loss of first condensators.
However, it is necessary to mean, that non-identical
inductivities will destroy linear voltage distribution
through cascades, and especially will shorten separate
cascades pulse front duration, that is very important for
diodes.
5. DIODES
Experimental and analytical study has shown
that charging diodes V1÷Vn, see Fig.1 a, work in much
harder conditions than discharging ones, as just after
passing of Ii pulse current they should go to a closed
state during back front of high voltage pulse. Diodes
KД203Д used in the beginning were not reliable for
f>10 Hz and were changed for KД206Д diodes with
shorter reverse time, the latter diodes do not demand
voltage distributor.
Assemblies of 59 this type diodes (for 25kV
voltage) can work up to f=100 Hz.
6. CONCLUSION
The exact calculation of MD voltage loss has
urged us to increase the number of cascades up to 32.
In addition the assemblies of KВИ-3 capacitors
with equivalent capacitance ~ 1000pF were mounted in
bridge to all diodes (both direct and inverse). They
serve to eliminate the cascades overvoltage when
breakdowns in accelerating tube or high-voltage
transformer occur.
For trouble-free operation at f=100Hz the
inductivities should be different. It is necessary to
connect each of the last 8 inductivities in bridge to the
same inductivity (thereby it may be possible to
eliminate their overcurrent); and for the first 8
inductivities it is necessary to increase their value 5-10
times (at the expense of the gap decreasing in a
magnetic conductor), and thus to diminish voltage
losses on the first capacities.
REFERENCES
1. A.S.Belov et al. // Proceedings of The XII
International Conference on Electrostatic
Accelerators. Obninsk, 1999, page 199-206. (in
Russian).
2. Yu.V.Belov et al. // Proceedings of The VIII All-
Union Conference on Charged Particle
Accelerators, Dubna, 1983, т. II, page 159. (in
Russian).
3. O.V.Elsukov et al. // Voprosy atomnoj nauki i
tehniki. Seria: Yaderno-fizicheskie issledovanija
(Teoria i eksperiment), 1989, vyp. (6), page 19. (in
Russian).
ВОПРОСЫ АТОМНОЙ НАУКИ И ТЕХНИКИ. 1999. № 4.
Серия: Ядерно-физические исследования (35), с. 38-39.
39
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| id | nasplib_isofts_kiev_ua-123456789-81524 |
| institution | Digital Library of Periodicals of National Academy of Sciences of Ukraine |
| issn | 1562-6016 |
| language | English |
| last_indexed | 2025-12-07T16:56:37Z |
| publishDate | 1999 |
| publisher | Національний науковий центр «Харківський фізико-технічний інститут» НАН України |
| record_format | dspace |
| spelling | Zubetz, V.N. Derbilov, V.I. Esin, S.K. Klenov, V.S. Nikulin, E.S. Frolov, O.T. Yakushev, V.P. 2015-05-17T16:35:08Z 2015-05-17T16:35:08Z 1999 Operation of the 400-750kV pulse voltage multi-cascade discriminator / V.N. Zubetz, V.I. Derbilov, S.K. Esin, V.S. Klenov, E.S. Nikulin, O.T. Frolov, V.P. Yakushev // Вопросы атомной науки и техники. — 1999. — № 4. — С. 38-39. — Бібліогр.: 3 назв. — англ. 1562-6016 https://nasplib.isofts.kiev.ua/handle/123456789/81524 The multi-cascade discriminator (МD) of the amplitude of pulsed 400-750kV voltage is an important part of the pulse high-voltage generator at the highcurrent linac injector of the Moscow meson factory [1]. It was invented and designed at the Efremov Institute of Electrophysical Apparature (Leningrad). It was partially tested at the factory [2] and successfully ran at 1 Hz repetition rate [3] in the adjusting mode of the accelerator. However the transition to 50Hz repetition rate gave rise to certain drawbacks, such as the current overloading of the inductivities, breakdown of the diodes and insufficient voltage. Analytical and experimental researches were conducted, and the required changes were made on their basis. These changes allowed the discriminator to operate with high reliability. The main results are set forth in this report. en Національний науковий центр «Харківський фізико-технічний інститут» НАН України Вопросы атомной науки и техники Operation of the 400-750kV pulse voltage multi-cascade discriminator Работа многоступенчатого ограничителя импульсного напряжения 400-750 кВ Article published earlier |
| spellingShingle | Operation of the 400-750kV pulse voltage multi-cascade discriminator Zubetz, V.N. Derbilov, V.I. Esin, S.K. Klenov, V.S. Nikulin, E.S. Frolov, O.T. Yakushev, V.P. |
| title | Operation of the 400-750kV pulse voltage multi-cascade discriminator |
| title_alt | Работа многоступенчатого ограничителя импульсного напряжения 400-750 кВ |
| title_full | Operation of the 400-750kV pulse voltage multi-cascade discriminator |
| title_fullStr | Operation of the 400-750kV pulse voltage multi-cascade discriminator |
| title_full_unstemmed | Operation of the 400-750kV pulse voltage multi-cascade discriminator |
| title_short | Operation of the 400-750kV pulse voltage multi-cascade discriminator |
| title_sort | operation of the 400-750kv pulse voltage multi-cascade discriminator |
| url | https://nasplib.isofts.kiev.ua/handle/123456789/81524 |
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