The capture efficiency of high field flux concentrator
A flux concentrator body cut leads to nonsymmetrical distortion of a transverse magnetic field. The results of positron tracking in distorted magnetic field and positron capture efficiency are presented in this paper for incident electron bunch energy of 6.2 GeV and tungsten positron production targ...
Saved in:
| Published in: | Вопросы атомной науки и техники |
|---|---|
| Date: | 2001 |
| Main Authors: | , |
| Format: | Article |
| Language: | English |
| Published: |
Національний науковий центр «Харківський фізико-технічний інститут» НАН України
2001
|
| Online Access: | https://nasplib.isofts.kiev.ua/handle/123456789/79245 |
| Tags: |
Add Tag
No Tags, Be the first to tag this record!
|
| Journal Title: | Digital Library of Periodicals of National Academy of Sciences of Ukraine |
| Cite this: | The capture efficiency of high field flux concentrator / R.M. Lapik, P.V. Martyshkin // Вопросы атомной науки и техники. — 2001. — № 3. — С. 106-107. — англ. |
Institution
Digital Library of Periodicals of National Academy of Sciences of Ukraine| _version_ | 1859618705960337408 |
|---|---|
| author | Lapik, R.M. Martyshkin, P.V. |
| author_facet | Lapik, R.M. Martyshkin, P.V. |
| citation_txt | The capture efficiency of high field flux concentrator / R.M. Lapik, P.V. Martyshkin // Вопросы атомной науки и техники. — 2001. — № 3. — С. 106-107. — англ. |
| collection | DSpace DC |
| container_title | Вопросы атомной науки и техники |
| description | A flux concentrator body cut leads to nonsymmetrical distortion of a transverse magnetic field. The results of positron tracking in distorted magnetic field and positron capture efficiency are presented in this paper for incident electron bunch energy of 6.2 GeV and tungsten positron production target with length of 5 rad.
|
| first_indexed | 2025-11-28T23:39:29Z |
| format | Article |
| fulltext |
THE CAPTURE EFFICIENCY OF HIGH FIELD FLUX
CONCENTRATOR
R.M. Lapik, P.V. Martyshkin
Budker Institute of Nuclear of Physics
11, Ac. Lavrentiev Ave, Novosibirsk, 630090, Russia
A flux concentrator body cut leads to nonsymmetrical distortion of a transverse magnetic field. The results of
positron tracking in distorted magnetic field and positron capture efficiency are presented in this paper for incident
electron bunch energy of 6.2 GeV and tungsten positron production target with length of 5 rad.
PACS numbers: 79.20.Mb, 29.17.+w, 29.25.-t
1 INTRODUCTION
At the present time a new generation of height lumi-
nosity linear colliders with a high intense bunches is un-
der construction. To provide a high intense positron
bunches a flux concentrator with high magnetic field
strength up to 10 Tesla or higher is used as a matching
device. The matching device like a flux concentrator has
a very important geometrical peculiarity - it is a flux
concentrator body cut from inside to external surface.
This body cut distorts a transverse magnetic field partic-
ularly in the plane of cut, thus the geometrical axis of
flux concentrator and axis of a transverse magnetic field
are not centered.
2 MAGNETIC FIELD
The flux concentrator body cut is a main geometrical
peculiarity. The magnetic field strength inside of the
gap is the same as the field strength on an axis of flux
concentrators or even higher. Operated peculiarity of a
flux concentrator is that an Eddy current inducted on a
outside surface comes through the gap on an internal
conical surface and concentrates at a minimum bore
aperture forming the area of strong magnetic field. The
Eddy current concentration is observed inside of gap as
well as to inside conical surface. The Eddy current,
moreover, is directed on a gap edge inside of the conical
area from the outcoming gap point to the minimum
aperture. By this way a local longitudinal component of
Eddy current is appeared on the internal conical surface.
This component of Eddy current forms a strong pla-
nar magnetic field directed in the plane of the gap which
has the same strength as a transverse field of the flux
concentrator for the ideal case (see Fig. 1). The ideal
case means not distorted magnetic field due to cut of
flux concentrator body. As a result the transverse mag-
netic field strength on the flux concentrator axis is about
10% - 15% of the longitudinal field strength at this
point. Magnetic field strength along the flux concentra-
tor axis and transverse field at different longitudinal po-
sition are presented in Fig. 2. Thus geometrical and
magnetic axes are displaced. The value of displacement
depends on the longitudinal position.
The distortion of longitudinal field is neglecting and
its magnetic axis is well centered with the geometrical
axis of flux concentrator.
Fig. 1. Azimuthal distribution at point z=3 cm for
distance from longitudinal axis 1, 2, 2.5 cm.
Fig. 2. Longitudinal and transverse field distribution.
3 FC CAPTURE EFFICIENCY
The magnetic and geometrical axes of an ideal
matching device are well centered and the strength of
transverse field on the axis is equal to zero. When the
transverse field is not equal to zero, positrons move in
the strong transverse field directed perpendicularly to
the main particle motion. As a result, positron bunch ob-
tains an additional angle and is not centered to the accel-
erator line. This displacement decreases the positron
capture efficiency.
In this paper a comparison of positron capture effi-
ciency was done for various strength of FC top magnet-
ВОПРОСЫ АТОМНОЙ НАУКИ И ТЕХНИКИ. 2001. №3.
Серия: Ядерно-физические исследования (38), с. 106-107.
106
ic field. The incident electron bunch is centered to geo-
metrical axes of the flux concentrator and accelerator
section. The parameters of FC and accelerator are the
following: minimum bore diameter of FC is 1 cm, FC
length is 16 cm, accelerating ratio is 25 MeV/m, diame-
ter of accelerator section is 2 cm. The solenoid field
strength is 0.5 Tesla.
Fig. 3. Positron yield for various flux concentrator
top field strengths.
Positron yield was simulated on the basis of GEANT
statistics and dynamics in flux concentrator, uniform
solenoid field. Energy cut at a positron bunch energy of
250 MeV is ±10 MeV and time cut is ± 30 ps. Positron
yield for the ideal matching device as FC and a device
with distorted transverse field is shown in Fig. 3. The
minimum aperture of the flux concentrator was taken of
1cm in diameter, solenoid field strength 0.5 Tesla. In the
second case the positron yield is less in twice or even
five times.
Fig. 4. Positron bunch emittance for the FC field of
15 Tesla.
Positron bunch center after passing the matching de-
vice is displaced from the accelerator section center for
1.2−1.4 cm. Positron bunch emittance for FC field of 15
Tesla and particles energy of 100 MeV in shown in Fig.
4.
4 CONCLUSION
As positron yield simulation shows, the capture effi-
ciency of the real matching device is as strong de-
creased as top field strength is higher. Thus, in order not
to lose a particle the transverse magnetic field of flux
concentrator should be compensated in addition. Anoth-
er way is to optimize a correct offset between geometri-
cal axes of FC and accelerator.
107
|
| id | nasplib_isofts_kiev_ua-123456789-79245 |
| institution | Digital Library of Periodicals of National Academy of Sciences of Ukraine |
| issn | 1562-6016 |
| language | English |
| last_indexed | 2025-11-28T23:39:29Z |
| publishDate | 2001 |
| publisher | Національний науковий центр «Харківський фізико-технічний інститут» НАН України |
| record_format | dspace |
| spelling | Lapik, R.M. Martyshkin, P.V. 2015-03-30T07:37:45Z 2015-03-30T07:37:45Z 2001 The capture efficiency of high field flux concentrator / R.M. Lapik, P.V. Martyshkin // Вопросы атомной науки и техники. — 2001. — № 3. — С. 106-107. — англ. 1562-6016 PACS numbers: 79.20.Mb, 29.17.+w, 29.25.-t https://nasplib.isofts.kiev.ua/handle/123456789/79245 A flux concentrator body cut leads to nonsymmetrical distortion of a transverse magnetic field. The results of positron tracking in distorted magnetic field and positron capture efficiency are presented in this paper for incident electron bunch energy of 6.2 GeV and tungsten positron production target with length of 5 rad. en Національний науковий центр «Харківський фізико-технічний інститут» НАН України Вопросы атомной науки и техники The capture efficiency of high field flux concentrator Эффективность захвата позитронов концентратором потока с высоким полем Article published earlier |
| spellingShingle | The capture efficiency of high field flux concentrator Lapik, R.M. Martyshkin, P.V. |
| title | The capture efficiency of high field flux concentrator |
| title_alt | Эффективность захвата позитронов концентратором потока с высоким полем |
| title_full | The capture efficiency of high field flux concentrator |
| title_fullStr | The capture efficiency of high field flux concentrator |
| title_full_unstemmed | The capture efficiency of high field flux concentrator |
| title_short | The capture efficiency of high field flux concentrator |
| title_sort | capture efficiency of high field flux concentrator |
| url | https://nasplib.isofts.kiev.ua/handle/123456789/79245 |
| work_keys_str_mv | AT lapikrm thecaptureefficiencyofhighfieldfluxconcentrator AT martyshkinpv thecaptureefficiencyofhighfieldfluxconcentrator AT lapikrm éffektivnostʹzahvatapozitronovkoncentratorompotokasvysokimpolem AT martyshkinpv éffektivnostʹzahvatapozitronovkoncentratorompotokasvysokimpolem AT lapikrm captureefficiencyofhighfieldfluxconcentrator AT martyshkinpv captureefficiencyofhighfieldfluxconcentrator |