Magnetic field losses in Nd-Fe-B magnets under 10 MeV electron irradiation
Reversible changes in magnetic properties of Nd-Fe-B magnets under electron beam with the energy of 10 MeV and bremsstrahlung irradiation were investigated. It was shown that direct electron beam irradiation resulted in the decrease of magnetic flux and substantial alteration in the magnetic pattern...
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| Zitieren: | Magnetic field losses in Nd-Fe-B magnets under 10 MeV electron irradiation / V.A. Bovda, A.M. Bovda, I.S. Guk, A.N. Dovbnya, V.N. Lyashchenko, A.O. Mytsykov, L.V. Onischenko, A.I. Kalinichenko, S.S. Kandybei, O.A. Repikhov // Вопросы атомной науки и техники. — 2017. — № 3. — С. 90-94. — Бібліогр.: 9 назв. — англ. |
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irk-123456789-1360952018-06-16T03:05:16Z Magnetic field losses in Nd-Fe-B magnets under 10 MeV electron irradiation Bovda, V.A. Bovda, A.M. Guk, I.S. Dovbnya, A.N. Lyashchenko, V.N. Mytsykov, A.O. Onischenko, L.V. Kalinichenko, A.I. Kandybei, S.S. Repikhov, O.A. Вычислительные и модельные системы Reversible changes in magnetic properties of Nd-Fe-B magnets under electron beam with the energy of 10 MeV and bremsstrahlung irradiation were investigated. It was shown that direct electron beam irradiation resulted in the decrease of magnetic flux and substantial alteration in the magnetic pattern on the surface of the samples. Increasing the radiation dose in 10 times did not lead to a linear reduction of magnetic flux. Bremsstrahlung also did not produce any significant drop in magnetic performance. Re-magnetization after the irradiation allowed to restore the initial magnetic properties of Nd-Fe-B magnets. Експериментально досліджений розподіл магнітного поля зразків магнітів, виготовлених з Nd-Fe-B сплаву, при опроміненні їх електронним пучком з енергією 10 МеВ, а також гальмівним випромінюванням такого пучка. Проведені дослідження показали, що величина і розподіл поля навколо магнітів змінюються при прямому опроміненні поверхні електронним пучком. Збільшення дози опромінення в 10 разів не приводить до лінійного зменшення поля зразка, який досліджувався. Під впливом гальмівного випромінювання електронів у зразку, розташованому поза впливом електронного пучка, істотної зміни магнітного поля не спостерігається. Повторне намагнічування зразка після опромінення електронним пучком дозволяє відновити первісну величину і розподіл поля навколо зразка. Экспериментально исследовано изменение магнитного поля образцов магнитов, изготовленных из Nd-Fe-B сплава, при облучении их электронным пучком с энергией 10 МэВ, а также тормозным излучением такого пучка. Проведенные исследования показали, что величина и распределение поля вокруг магнитов изменяются при прямом облучении поверхности электронным пучком. Увеличение дозы облучения в 10 раз не приводит к линейному изменению наблюдаемого изменения поля образца. Под воздействием тормозного излучения электронов в образце, расположенном вне воздействия электронного пучка, существенного изменения поля не наблюдается. Повторное намагничивание образца после облучения электронным пучком позволяет восстановить первоначальную величину и распределение поля вокруг образца. 2017 Article Magnetic field losses in Nd-Fe-B magnets under 10 MeV electron irradiation / V.A. Bovda, A.M. Bovda, I.S. Guk, A.N. Dovbnya, V.N. Lyashchenko, A.O. Mytsykov, L.V. Onischenko, A.I. Kalinichenko, S.S. Kandybei, O.A. Repikhov // Вопросы атомной науки и техники. — 2017. — № 3. — С. 90-94. — Бібліогр.: 9 назв. — англ. 1562-6016 PACS: 75.50.-y, 61.80.-x, 71.20.Eh http://dspace.nbuv.gov.ua/handle/123456789/136095 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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Вычислительные и модельные системы Вычислительные и модельные системы |
| spellingShingle |
Вычислительные и модельные системы Вычислительные и модельные системы Bovda, V.A. Bovda, A.M. Guk, I.S. Dovbnya, A.N. Lyashchenko, V.N. Mytsykov, A.O. Onischenko, L.V. Kalinichenko, A.I. Kandybei, S.S. Repikhov, O.A. Magnetic field losses in Nd-Fe-B magnets under 10 MeV electron irradiation Вопросы атомной науки и техники |
| description |
Reversible changes in magnetic properties of Nd-Fe-B magnets under electron beam with the energy of 10 MeV and bremsstrahlung irradiation were investigated. It was shown that direct electron beam irradiation resulted in the decrease of magnetic flux and substantial alteration in the magnetic pattern on the surface of the samples. Increasing the radiation dose in 10 times did not lead to a linear reduction of magnetic flux. Bremsstrahlung also did not produce any significant drop in magnetic performance. Re-magnetization after the irradiation allowed to restore the initial magnetic properties of Nd-Fe-B magnets. |
| format |
Article |
| author |
Bovda, V.A. Bovda, A.M. Guk, I.S. Dovbnya, A.N. Lyashchenko, V.N. Mytsykov, A.O. Onischenko, L.V. Kalinichenko, A.I. Kandybei, S.S. Repikhov, O.A. |
| author_facet |
Bovda, V.A. Bovda, A.M. Guk, I.S. Dovbnya, A.N. Lyashchenko, V.N. Mytsykov, A.O. Onischenko, L.V. Kalinichenko, A.I. Kandybei, S.S. Repikhov, O.A. |
| author_sort |
Bovda, V.A. |
| title |
Magnetic field losses in Nd-Fe-B magnets under 10 MeV electron irradiation |
| title_short |
Magnetic field losses in Nd-Fe-B magnets under 10 MeV electron irradiation |
| title_full |
Magnetic field losses in Nd-Fe-B magnets under 10 MeV electron irradiation |
| title_fullStr |
Magnetic field losses in Nd-Fe-B magnets under 10 MeV electron irradiation |
| title_full_unstemmed |
Magnetic field losses in Nd-Fe-B magnets under 10 MeV electron irradiation |
| title_sort |
magnetic field losses in nd-fe-b magnets under 10 mev electron irradiation |
| publisher |
Національний науковий центр «Харківський фізико-технічний інститут» НАН України |
| publishDate |
2017 |
| topic_facet |
Вычислительные и модельные системы |
| url |
http://dspace.nbuv.gov.ua/handle/123456789/136095 |
| citation_txt |
Magnetic field losses in Nd-Fe-B magnets under 10 MeV electron irradiation / V.A. Bovda, A.M. Bovda, I.S. Guk, A.N. Dovbnya, V.N. Lyashchenko, A.O. Mytsykov, L.V. Onischenko, A.I. Kalinichenko, S.S. Kandybei, O.A. Repikhov // Вопросы атомной науки и техники. — 2017. — № 3. — С. 90-94. — Бібліогр.: 9 назв. — англ. |
| series |
Вопросы атомной науки и техники |
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2025-07-10T00:38:02Z |
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2025-07-10T00:38:02Z |
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| fulltext |
MAGNETIC FIELD LOSSES IN Nd− Fe−B MAGNETS
UNDER 10MeV ELECTRON IRRADIATION
V.A.Bovda, A.M.Bovda, I. S.Guk∗, A.N.Dovbnya, V.N.Lyashchenko,
A.O.Mytsykov, L.V.Onischenko, A. I.Kalinichenko, S. S.Kandybei,
O.A.Repikhov
National Science Center ”Kharkiv Institute of Physics and Technology”, 61108, Kharkiv, Ukraine
(Received April 10, 2017)
Reversible changes in magnetic properties of Nd−Fe−B magnets under electron beam with the energy of 10MeV
and bremsstrahlung irradiation were investigated. It was shown that direct electron beam irradiation resulted in the
decrease of magnetic flux and substantial alteration in the magnetic pattern on the surface of the samples. Increasing
the radiation dose in 10 times did not lead to a linear reduction of magnetic flux. Bremsstrahlung also did not produce
any significant drop in magnetic performance. Re-magnetization after the irradiation allowed to restore the initial
magnetic properties of Nd− Fe−B magnets.
PACS: 75.50.-y, 61.80.-x, 71.20.Eh
1. INTRODUCTION
Rare-earth permanent magnets are widely used in the
self-powered compact devices [1,2]. Now, Nd−Fe−B
magnets are the essential part of technological elec-
tron accelerators with energy up to 10MeV . Mag-
nets have many practical applications as focusing
beam systems and energy beam measuring devices
[3,4]. However, the stability of magnetic performance
can be influenced by the direct electron beam and
bremsstrahlung irradiation [5]. In this paper, we
present the study of magnetic performance stabil-
ity of Nd − Fe − B magnets under electron and
bremsstrahlung irradiation. Nd − Fe − B mag-
nets were manufactured using PLP technology [6,7].
KUT-1 technological accelerator [8] with the energy
of 10MeV was used as the source of the electron
beam. The density of magnetic samples obtained
with PLP technology was 7.35...7.4 g/cm3. The mag-
nets had geometrical dimensions of 30×40×12mm3.
The surface of the samples was covered with a thin
layer of nickel to prevent corrosion. During the ir-
radiation, the samples were cooled with water at a
temperature of no more than 40◦C. Pulsed magnetic
field of 3.5T was used for samples magnetization.
2. EXPERIMENTAL SETUP
The direct irradiation experiments were carried out
with three magnets designates as M1, M4 and M5.
All samples were located behind output foil of the
accelerator. Continued water cooling was used to pre-
vent samples from heating. The side (30×40mm2) of
South magnetic pole (S. pole) was chosen for the di-
rect electron irradiation. The heterogeneity of beam
density was less than 10%. The M2 sample under-
went bremsstrahlung radiation generated by electron
bombardment of M1 sample. In view of this, M2
sample was placed beyond electron beam. The dis-
tance between M1 and M2 samples was 1 cm. The
M2 sample was also water-cooled. The non-irradiated
M3 sample was used for reference measurements of
induced activity and magnetic flux stability. M1, M2
and M4 samples were exposed to continue irradia-
tion within 20hours. The absorbed dose of M1 and
S4 samples was 16Grad. M5 sample was irradiated
within 20hours sessions with 24 hours breaks. The
total absorbed dose for M5 sample was 160Grad.
The γ-spectra of each irradiated sample were col-
lected within 24hours after the end of irradiation.
CANBERRA GC1818 spectrometer with high-purity
Ge semiconductor detector was utilized. As a result
of 148Nd(γ, n)147Nd reaction with the threshold of
7.3MeV , the unstable 174Nd isotope with 10.98 days
half-life was revealed. The 174Nd isotope attributes
to 91.136, 319.406, 439.835, 530.913 keV . However,
174Nd isotope did not considerably change the activ-
ity of the samples in comparison with non-irradiated
one. Thus, negligible induced activity enables to use
Nd − Fe − B magnets at the technological electron
accelerators.
3. MAGNETIC MEASUREMENTS
Magnetic measurements were performed by the seven
(7) Hall probes assembly [9]. Hall probes were fixed
in the copper matrix to temperature compensation.
The distance between Hall probes was 6mm. The
normal component of the magnetization was mea-
sured. The relative accuracy was not less than 0.01%.
∗Corresponding author E-mail address: guk@kipt.kharkov.ua
90 ISSN 1562-6016. PROBLEMS OF ATOMIC SCIENCE AND TECHNOLOGY, 2016, N3(109).
Series: Nuclear Physics Investigations (68), p.90-94.
Magnetic samples were moved parallel to the surface
of the copper matrix. The distance between mag-
nets and copper matrix was 3.05mm. The steps of
measurements along the direction of travel varied
from 3 to 5mm. The accuracy of travel was 1µm.
Initial reference point was fixed by the supporting
system. The magnetic field distribution (magnetic
flux) was scanned from the both sides of the magnet
(30× 40mm2). Fig.1 shows the North pole (N. pole)
magnetic scans for M1 sample before irradiation.
Fig.1. Magnetic field scans for M1 sample (N. pole)
Scanned data were used for the three-dimension
square interpolation. The area of simulation was
limited by the out-to-out Hall probes positions in
the copper matrix and scanning area. Fig.2 demon-
strates the simulation for the M1 sample utilizing
data shown in Fig.1.
Fig.2. Simulation of magnetic flux for M1 sample
(N. pole)
The magnetic field around the sample can be de-
scribed by the integral Bx component in a plane
3.05mm of the surface of the block. The in-
tegral Bx component of magnetic flux measured
at the N. pole side of non-irradiated samples
is shown in Table. It was revealed, that inte-
gral Bx component of magnetic fluxes at both
sides of the non-irradiated samples showed good
agreement within the accuracy of measurements.
Integral value of magnetic flux of the samples
Name Integral Bx component
Name (N. pole) , arb. units
M1 175.763
M2 179.556
M3 175.452
M4 174.275
M5 176.357
The carried out examinations accuracy of recurring
of integral Bx component for the same sample, re-
lated to a binding to boundaries of the sample of a
measuring system, give repeatability at level of 0.5%.
4. RESULTS AFTER ELECTRON
IRRADIATION
The simulation of magnetic field distribution for the
sample after electron irradiation is shown in Figs.3-8.
The simulation of the magnetic field distribution of
M1 for S. pole is depicted in Fig.4. The corresponding
integral Bx component of M1 sample for S. pole was
−160.2. It can be seen that integral Bx component
for M1 equals to 162.356 for N. pole. As it can be
seen in Figs.3 and 4, the magnetic field distribution
of both N. and S. poles are in a good agreement after
electron irradiation, within the accuracy of measure-
ments.
Simulated magnetic field distribution for M4 sam-
ple (N. pole) after irradiation is shown in Fig.5. It
was revealed that integral Bx component (N. pole)
for M4 sample after irradiation dropped to 151.122.
The shape of the simulated magnetic field distribu-
tion of S. pole for M4 sample is close to the pattern
in the Fig.5. The integral Bx component of S. pole
for M4 sample is about −151.509.
Fig.3. The simulation of magnetic field distribution
for M1 sample (N. pole) after irradiation (accumu-
lated dose 16Grad)
91
Fig.4. Simulated magnetic field distribution for M1
sample (S. pole) after irradiation
Fig.5. The simulation of magnetic field distribution
for M4 sample (N. pole) after irradiation (accumu-
lated dose 16Grad)
Whereas direct electron irradiation substantially
modified the magnetic pattern of the samples,
bremsstrahlung irradiation hardly changed the
magnetic field distribution (see Fig.6) and inte-
gral Bx component of 178.526 (see also Table).
Fig.6. Simulated magnetic field distribution N. pole
of M2 sample
Predictably, the most transformation of mag-
netic field distribution was found for M5 sample
with the highest accumulated dose of 160Grad
(Fig.7). The integral Bx component was reduced to
126.556. It should be noted that integral Bx compo-
nent was not proportional to the accumulated dose.
Fig.7. Magnetic field distribution for M5 sam-
ple (N. pole) after irradiation (accumulated dose
160Grad)
5. EFFECTS OF ACTION OF AN
EXTERIOR MAGNETIC FIELD
The full recovery of magnetic properties was indi-
cated for M1 and M4 samples after re-magnetization.
Figs.8-10 shows the simulated magnetic field distribu-
tion of M1 and M5 samples after re-magnetization.
After irradiation (see Fig.3) and re-magnetization
(Fig.8) of M1 sample, the pattern of N. pole mag-
netic field distribution was slightly changed and al-
most coincided with the initial state (see Fig.1).
The integral Bx component was about 175.224,
which is in good agreement with the initial value.
Fig.8. Magnetic field distribution N. pole of M1
sample after irradiation and re-magnetization.
The same effect was indicated for M5 sample (see
Figs.9 and 10). The integral Bx component of M5
sample after re-magnetization recovered to the initial
value of 174.894 (N. pole) and −176.78 (S. pole).
92
Fig.9. Magnetic field distribution N. pole of M5
sample after irradiation and re-magnetization
Fig.10. Magnetic field distribution S. pole of M5
sample after irradiation and re-magnetization
6. SUMMARY
The direct electron irradiation of the Nd-Fe-B mag-
nets let to the substantial change in magnetic field
distribution of the samples. There was no direct
correlation between the decrease of magnetic prop-
erties and the accumulated dose within the range of
16...160Grad. Re-magnetization of the samples after
irradiation resulted in the full recovery of magnetic
properties. Within the interval of the used radiation
absorption doses of the electron beam, no dependence
of this effect on the dose was observed. Within the
indicated doses, there was no significant change in
the activity of the samples due to the formation of
unstable isotopes in the material of magnets, which
makes it possible to simplify the use of finished prod-
ucts on technological accelerators with energy of up
to 10MeV .
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93
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ÅËÅÊÒÐÎÍÍÈÌ ÏÓ×ÊÎÌ Ç ÅÍÅÐÃI�Þ 10 Ìå ÍÀ ÂÅËÈ×ÈÍÓ ÏÎËß
ÍÀÂÊÎËÎ ÌÀÃÍIÒÓ
Â.Î.Áîâäà, Î.Ì.Áîâäà, I.Ñ.Ãóê, À.Ì.Äîâáíÿ, Â.Ì.Ëÿùåíêî,
À.Î.Ìèöèêîâ, Ë.Â.Îíiùåíêî, Î. I.Êàëiíi÷åíêî, Ñ.Ñ.Êàíäèáåé, Î.Î.Ðåïiõîâ
Åêñïåðèìåíòàëüíî äîñëiäæåíèé ðîçïîäië ìàãíiòíîãî ïîëÿ çðàçêiâ ìàãíiòiâ, âèãîòîâëåíèõ ç Nd−Fe−B
ñïëàâó, ïðè îïðîìiíåííi ¨õ åëåêòðîííèì ïó÷êîì ç åíåðãi¹þ 10 ÌåÂ, à òàêîæ ãàëüìiâíèì âèïðîìiíþ-
âàííÿì òàêîãî ïó÷êà. Ïðîâåäåíi äîñëiäæåííÿ ïîêàçàëè, ùî âåëè÷èíà i ðîçïîäië ïîëÿ íàâêîëî ìàãíiòiâ
çìiíþþòüñÿ ïðè ïðÿìîìó îïðîìiíåííi ïîâåðõíi åëåêòðîííèì ïó÷êîì. Çáiëüøåííÿ äîçè îïðîìiíåííÿ â
10 ðàçiâ íå ïðèâîäèòü äî ëiíiéíîãî çìåíøåííÿ ïîëÿ çðàçêà, ÿêèé äîñëiäæóâàâñÿ. Ïiä âïëèâîì ãàëüìiâ-
íîãî âèïðîìiíþâàííÿ åëåêòðîíiâ ó çðàçêó, ðîçòàøîâàíîìó ïîçà âïëèâîì åëåêòðîííîãî ïó÷êà, iñòîòíî¨
çìiíè ìàãíiòíîãî ïîëÿ íå ñïîñòåðiãà¹òüñÿ. Ïîâòîðíå íàìàãíi÷óâàííÿ çðàçêà ïiñëÿ îïðîìiíåííÿ åëåê-
òðîííèì ïó÷êîì äîçâîëÿ¹ âiäíîâèòè ïåðâiñíó âåëè÷èíó i ðîçïîäië ïîëÿ íàâêîëî çðàçêà.
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