Peculiarities of electromagnetic filter operation in penning source with metal hydride cathode

The paper describes a method of negative hydrogen ions separation from axial flow of charged particles extract- ed from Penning discharge with a metal hydride cathode. For this purpose, an electromagnetic filter has been designed basing on numerical solution of motion equations of charged particles...

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Datum:	2020
Hauptverfasser:	Sereda, I., Hrechko, Ya., Babenko, Ie., Kashaba, A.
Format:	Artikel
Sprache:	English
Veröffentlicht:	Національний науковий центр «Харківський фізико-технічний інститут» НАН України 2020
Schriftenreihe:	Вопросы атомной науки и техники
Schlagworte:	Low temperature plasma and plasma technologies
Online Zugang:	http://dspace.nbuv.gov.ua/handle/123456789/194655
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Zitieren:	Peculiarities of electromagnetic filter operation in penning source with metal hydride cathode / I. Sereda, Ya. Hrechko, Ie. Babenko, A. Kashaba // Problems of atomic science and tecnology. — 2020. — № 6. — С. 111-114. — Бібліогр.: 7 назв. — англ.

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spelling	irk-123456789-1946552023-11-28T14:14:16Z Peculiarities of electromagnetic filter operation in penning source with metal hydride cathode Sereda, I. Hrechko, Ya. Babenko, Ie. Kashaba, A. Low temperature plasma and plasma technologies The paper describes a method of negative hydrogen ions separation from axial flow of charged particles extract- ed from Penning discharge with a metal hydride cathode. For this purpose, an electromagnetic filter has been designed basing on numerical solution of motion equations of charged particles in the filter. The optimal parameters of the filter operation were determined for the effective registration of negative hydrogen ions extracted in axial direction. Performed calculations together with experimental verification shows that there are not more than 10 % electrons in the registered Н ⁻ current. This model could be applied for the interpretation of any experiments with Н ⁻ ions separation from an axial flow of charged particles extracted from a source with cylindrical geometry. Описаний метод сепарації негативних іонів водню з аксіального потоку заряджених частинок, що виходять із розряду Пеннінга з металогідридним катодом. З цією метою на основі чисельного рішення рівняння руху заряджених частинок був розроблений електромагнітний фільтр. Визначено оптимальні параметри роботи фільтра для ефективної реєстрації негативних іонів водню, що виходять в аксіальному напрямку. Зроблені розрахунки разом з експериментальною перевіркою показали, що не більше 10% електронів реєструються в струмі негативних іонів водню. Ця модель може бути застосована для інтерпретації будь-яких експериментів по сепарації іонів Н ⁻ з аксіального потоку заряджених частинок, що витягаються з джерела, що має циліндричну геометрію. Описан метод сепарации отрицательных ионов водорода из аксиального потока заряженных частиц, выходящих из разряда Пеннинга с металлогидридным катодом. С этой целью на основе численного решения уравнения движения заряженных частиц разработан электромагнитный фильтр. Определены оптимальные параметры работы фильтра для эффективной регистрации отрицательных ионов водорода, выходящих в аксиальном направлении. Проделанные расчеты вместе с экспериментальной проверкой показали, что не более 10% электронов содержится в регистрируемом токе отрицательных ионов водорода. Данная модель может быть применена для интерпретации любых экспериментов по сепарации ионов Н ⁻ из аксиального потока заряженных частиц, извлекаемых из источника с цилиндрической геометрией. 2020 Article Peculiarities of electromagnetic filter operation in penning source with metal hydride cathode / I. Sereda, Ya. Hrechko, Ie. Babenko, A. Kashaba // Problems of atomic science and tecnology. — 2020. — № 6. — С. 111-114. — Бібліогр.: 7 назв. — англ. 1562-6016 PACS: 52.80.Sm http://dspace.nbuv.gov.ua/handle/123456789/194655 en Вопросы атомной науки и техники Національний науковий центр «Харківський фізико-технічний інститут» НАН України
institution	Digital Library of Periodicals of National Academy of Sciences of Ukraine
collection	DSpace DC
language	English
topic	Low temperature plasma and plasma technologies Low temperature plasma and plasma technologies
spellingShingle	Low temperature plasma and plasma technologies Low temperature plasma and plasma technologies Sereda, I. Hrechko, Ya. Babenko, Ie. Kashaba, A. Peculiarities of electromagnetic filter operation in penning source with metal hydride cathode Вопросы атомной науки и техники
description	The paper describes a method of negative hydrogen ions separation from axial flow of charged particles extract- ed from Penning discharge with a metal hydride cathode. For this purpose, an electromagnetic filter has been designed basing on numerical solution of motion equations of charged particles in the filter. The optimal parameters of the filter operation were determined for the effective registration of negative hydrogen ions extracted in axial direction. Performed calculations together with experimental verification shows that there are not more than 10 % electrons in the registered Н ⁻ current. This model could be applied for the interpretation of any experiments with Н ⁻ ions separation from an axial flow of charged particles extracted from a source with cylindrical geometry.
format	Article
author	Sereda, I. Hrechko, Ya. Babenko, Ie. Kashaba, A.
author_facet	Sereda, I. Hrechko, Ya. Babenko, Ie. Kashaba, A.
author_sort	Sereda, I.
title	Peculiarities of electromagnetic filter operation in penning source with metal hydride cathode
title_short	Peculiarities of electromagnetic filter operation in penning source with metal hydride cathode
title_full	Peculiarities of electromagnetic filter operation in penning source with metal hydride cathode
title_fullStr	Peculiarities of electromagnetic filter operation in penning source with metal hydride cathode
title_full_unstemmed	Peculiarities of electromagnetic filter operation in penning source with metal hydride cathode
title_sort	peculiarities of electromagnetic filter operation in penning source with metal hydride cathode
publisher	Національний науковий центр «Харківський фізико-технічний інститут» НАН України
publishDate	2020
topic_facet	Low temperature plasma and plasma technologies
url	http://dspace.nbuv.gov.ua/handle/123456789/194655
citation_txt	Peculiarities of electromagnetic filter operation in penning source with metal hydride cathode / I. Sereda, Ya. Hrechko, Ie. Babenko, A. Kashaba // Problems of atomic science and tecnology. — 2020. — № 6. — С. 111-114. — Бібліогр.: 7 назв. — англ.
series	Вопросы атомной науки и техники
work_keys_str_mv	AT seredai peculiaritiesofelectromagneticfilteroperationinpenningsourcewithmetalhydridecathode AT hrechkoya peculiaritiesofelectromagneticfilteroperationinpenningsourcewithmetalhydridecathode AT babenkoie peculiaritiesofelectromagneticfilteroperationinpenningsourcewithmetalhydridecathode AT kashabaa peculiaritiesofelectromagneticfilteroperationinpenningsourcewithmetalhydridecathode
first_indexed	2025-07-16T22:03:27Z
last_indexed	2025-07-16T22:03:27Z
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fulltext	ISSN 1562-6016. ВАНТ. 2020. №6(130) PROBLEMS OF ATOMIC SCIENCE AND TECHNOLOGY. 2020, № 6. Series: Plasma Physics (26), p. 111-114. 111 https://doi.org/10.46813/2020-130-111 PECULIARITIES OF ELECTROMAGNETIC FILTER OPERATION IN PENNING SOURCE WITH METAL HYDRIDE CATHODE I. Sereda, Ya. Hrechko, Ie. Babenko, A. Kashaba V.N. Karazin Kharkiv National University, Kharkiv, Ukraine E-mail: igorsereda@karazin.ua The paper describes a method of negative hydrogen ions separation from axial flow of charged particles extract- ed from Penning discharge with a metal hydride cathode. For this purpose, an electromagnetic filter has been de- signed basing on numerical solution of motion equations of charged particles in the filter. The optimal parameters of the filter operation were determined for the effective registration of negative hydrogen ions extracted in axial direc- tion. Performed calculations together with experimental verification shows that there are not more than 10% elec- trons in the registered H – current. This model could be applied for the interpretation of any experiments with H – ions separation from an axial flow of charged particles extracted from a source with cylindrical geometry. PACS: 52.80.Sm INTRODUCTION The metal hydride hydrogen activation increases the efficiency of negative Н – ions formation by the mecha- nism of dissociative attachment in the plasma volume [1]. For the flux of accompanying electrons reduction negative ions are traditionally extracted across the mag- netic field, for example, through an aperture in the an- ode, as it was realized in an Eller’s-type source [2]. The source design with metal hydride cathode could be greatly simplified due to the discharge properties chang- ing [3]. It appears that at high discharge voltages a flow of negatively charged particles including negative ions and electrons along with positive ions starts yielding along the external magnetic field [4]. Picking up the value of external magnetic field, electric supply and discharge dimensions one could achieve the situation when the current of positive ions will be much lower than the negative one. In [4] an electromagnetic filter was proposed for the separation of Н – ions in the axial flow. The methodolo- gy for calculating the filter parameters and the trajectory of charged particles according to the properties of the discharge [3] is given in [5]. But a change in discharge parameters, such as electrodes geometry, electrical sup- ply and local injection of activated hydrogen from metal hydride cathode, impacts the axial flow of charged par- ticles. In particular, the optimal parameters of the filter operation are changing. Thus, verification of experi- mental data requires additional calculations. This work summarizes the results obtained earlier, demonstrates the influence of the electric potentials of the filter electrodes and the distribution of the magnetic field on the trajectories of charged particles for the ef- fective registration of negative hydrogen ions extracted in axial direction. 1. FILTER CONSTRUCTION A cathode unit with electromagnetic filter, which was created in [5] is shown in Fig. 1. It consists a cop- per cathode-reflector and a magnetic filter which in- cludes a grid (1), electrons current collector (2), a coil of magnetic field (4) and a collector of negative ions (5). The copper cathode-reflector (3) has got an aperture in the center 0.5 cm in diameter for charged particles ex- traction. The distance between the cathode-reflector of Penning cell (3), the grid (1) and the electron collector (2) were the same and were 0.4 cm. The ion collector (5) was at the distance of 1.8 cm from the copper cath- ode-reflector (3). The cathodes and collectors were un- der ground potential. The grid (1) was supplied with positive potential for positive particles removing. Fig. 1. The cathode unit with electromagnetic filter: 1 – retarding grid; 2 – copper cathode-reflector with an aperture; 3 – electrons collector; 4 – coil of the filter magnetic field; 5 – H – ion collector The whole electrodes system was placed in external uniform longitudinal magnetic field Hzo0 with intensity that could be changed in the range of Hzo0 = 0...0.1 T. The filter construction provides an idea for the creation of reverse magnetic field in the gap between the cathode (3) and the collector (5) to deflect electrons, but not impact on H – ions. The unit design also assumed that magnetic field of the filter Hcoil do not distorted the uni- form magnetic field Hzo0 in the discharge cell. Ugrid 3 1 2 4 5 Icol z Hz0 6 Hzo0 cm 0 1 2 3 4 Hcoil Ucat 112 ISSN 1562-6016. ВАНТ. 2020. №6(130) 2. CALCULATION METHOD Taking into account the configuration of the elec- trodes, which ensures the registration of only the parax- ial group of particles, the equation of motion can be obtained in the paraxial approximation in similar way as it was done in [6]: 01 82 1 2 0 2 0 2 0 2 0 22 2                     z zo o z o o Hr HrrH mc q dz dr dz rd   , where  z o ,0  is a potential on the discharge axis relative to the potential of the particle creation point  z o ,0  , which depends on electric potential of the cathode (3) (see Fig. 1). 0 0  o  in case of ground po- tential on the cathode. r0 is the radius of the particle’s entry into the gap. To solve equation non-uniform mag- netic and electric fields in the investigated gap must be specified. The profile of magnetic field in equation de- pends on two variables:  00 ,0 zHH zo  is a magnetic field on the axis at the emitter point z0. The fixed value of 0.06, 0.08, and 0.1 T were selected for 0zoH .  zHH z ,00  is the profile of inhomogeneous magnetic field on the axis in the cathode-collector gap, which is created by the counter-switching of the coils on the axis at an arbitrary point. 0,0 0,2 0,4 0,6 0,8 1,0 1,2 1,4 1,6 1,8 0,00 0,02 0,04 0,06 0,08 0,10 H z0 , T z, cm H zo0 = 0.06 T H zo0 = 0.08 T H zo0 = 0.1 T Fig. 2. The magnetic field distribution in the gap cath- ode (z = 0 cm)-collector (z = 1.8 cm) 0.0 0.2 0.4 0.6 0.8 1.0 1.2 1.4 1.6 1.8 0 200 400 600 800 1000 f , V z, cm Fig. 3. The electrical potential distribution in the gap cathode (z = 0 cm)-collector (z = 1.8 cm) The profiles Hz0 (Fig. 2) and  z o ,0  (Fig. 3) were calculated in the program femm 4.0 basing on the geometric dimensions of the cathode unit, the potentials of the electrodes and the coil current. Equation was obtained under the assumption of a slowly varied electric and magnetic fields in longitudi- nal direction. The solution of the eq. was carried out numerically by the fourth-order Runge-Kutta method and the result is a paraxial trajectory equation in meridian plane r = r(z). 3. RESULTS AND DISCUSSION The result of the numerical solution is the depend- ence of the particle position r(z) at a certain value of the longitudinal coordinate z in the cathode-collector gap. These results are presented in the Fig. 4. The position and size of the coil and the collector correspond to the figure scale. In our calculations, the position z = 0.0 cm corresponds to the cathode edge and z = 1.8 cm – to the collector edge. The presented results demonstrate the important role of the filter grid (1) (see Fig. 1). The supply of a posi- tive potential Ugrid to the grid, in addition to the reflec- tion of positive Н2 + ions, also accelerates the negative component of the flow. Thus, it is possible to separate the trajectories of electrons and H – ions using the trans- verse component of the magnetic field. Taking into account that in some modes of the dis- charge operation only negative particles yield in the longitudinal direction [3, 7], it would be a mistake to completely remove the grid (1). This is due to the ratio of the energies of electrons and H – ions which is ap- proximately equal to the root of the ratio of their mass- es. Thus, the magnetic field will deflect them at close angles and separation will not be effective. The oscillat- ing behavior of the curves here is apparently related to the projection of the Larmor motion of the low energy particles on the r(z) plane. Otherwise the reversal magnetic field has a little ef- fect on the trajectory of H – ions, whereas, electron tra- jectories significantly curves, and at the value of total magnetic field Hz0 = 0 at z = 1.8 cm (collector edge) the electrons are diverted. It should be noted that the end of electron trajecto- ries essentially depends on the initial value of the con- stant r0, where r0 is the radius of electron entry in the gap. For example, at zero magnetic field on the collector edge and r0 > 0.08 cm all the electrons are diverted. Accordingly, electrons that moves strictly in the coaxial tube 0.16 cm in diameter slightly diverted by magnetic field and registered by the ion’s collector. In other words, only electrons, which have an entrance radius r0 ≤ 0.08 cm pass through. The magnetic field in the gap has weak effect on them. The rest main part of electrons is successfully diverted. Estimates shown that the cur- rent of passed electrons should be an order of magnitude smaller than the diverted one. In the same time the tra- jectories of ions had been little effect magnetic field on. Thus, when the electromagnetic field operates with the required parameters, the measured current on collec- tor (5) could be associated with H – ions. In case of the filter is switched off (Hcoil = 0 and φ0 = 0) one can measure the total current of charged particles included H2 + , H – , e – outgoing in axial direction. ISSN 1562-6016. ВАНТ. 2020. №6(130) 113 Fig. 4. The trajectories of electrons and negative ions in the gap cathode (z = 0 cm)-collector (z = 1.8 cm) A positive potential supply to the cathode still weak- ly affects the ion trajectories, but the electrons, at the same time, are deflected by a larger angle by the mag- netic field. So, it even further increases the filter effi- ciency. The electromagnetic filter operation as a part of a Penning cell with metal hydride cathode is shown in Fig. 5. Here is a typical dependence of the collector cur- rent Icol depending on the ratio of the external magnetic field Hzo0 = 0.1 T to the magnetic field Hcoil, which is created by the filter coil. The value of Hzo0 / Hcoil = 1 corresponds to the calculated trajectories of charged particles shown in Fig. 4 (black curves). The discharge voltage Ud = 5 kV, the pressure p = 5∙10 -6 Torr and the grid potential Ugrid = 1 kV were selected on the base of the discharge features and corre- sponded to the mode when a negative axial current of charged particles was registered [4]. One can see from the figure, an increase of Hcoil causes the growth of transverse component of the mag- netic field, which deflects the electrons. According to the calculations the ratio Hzo0 / Hcoil = 1 is optimal for electron diverting. However, the experiment showed that this value can lie in the range from 0.6 to 1.1 (Fig. 5). The decrease of the current at Hzo0 / Hcoil > 1.1 is hardly related to the deviation of negative ions, since in this case the magnetic field Hcoil will no longer be con- centrated only in the cathode-collector gap, but will penetrate into the plasma region and will distort the uni- form magnetic field Hzo0 in the discharge cell. 0,5 1,0 1,5 -16 -14 -12 -10 -8 -6 -4 -2 0 I co l, m A Hcoil / Hzo0 Fig. 5. The dependence of collector current Icol on Hcoil / Hzo0 (Hzo0 = 0.1 T, Ud = 5 kV, Ugrid = 1 kV, p = 5∙10 -6 Torr) Thus, the obtained data are in good agreement with the calculation. 0.2 0.4 0.6 0.8 1.0 1.2 1.4 1.6 0.10 0.15 0.20 0.25 0.30 0.35 0.40 0.10 0.15 0.20 0.25 0.30 0.35 H - - ion collector electron trajectories U grid = 1 kV H - ion trajectories U grid = 1 kV r, c m z, cm ca th od e- re fl ec to r gr id -0.40 -0.35 -0.30 -0.25 -0.20 -0.15 -0.10 -0.35 -0.30 -0.25 -0.20 -0.15 -0.10 H - - ion collector electron trajectories U grid = 0 V H - ion trajectories U grid = 0 V ca th od e- re fl ec to r 114 ISSN 1562-6016. ВАНТ. 2020. №6(130) CONCLUSIONS The separation of H – ions flow from electrons and positive ions could be made with electro-magnetic filter. Positive ions are retarded by electric field of the grid and electrons are diverted by magnetic field. Performed calculations together with experimental verification shows that there are not more than 10% electrons in the registered H – current. At the same time, electrical field of the grid fully reflects positive ions. Summarizing the numerous calculations expands the range of the best external parameters for the efficient separation of H – ions from the axial flow of charged particles. This mod- el could be applied for the interpretation of any experi- ments with H – ions separation from an axial flow of charged particles extracted from a source with cylindri- cal geometry. REFERENCES 1. I. Sereda, A. Tseluyko, N. Azarenkov. The Applica- tion of Metal Hydride Based on Zr-V Alloy in Hydrogen Plasma // Patrick C. Dam, editor. Hydrides: Types, Bonds and Applications, New York: «Nova Science Publishers Inc». 2018, p. 149-192. 2. M. Bacal, M. Wada. Negative hydrogen ion produc- tion mechanisms // Appl. Phys. Rev. 2015, v. 2, p. 021305. 3. I.V. Borgun, D.L. Ryabchikov, I.N. Sereda, A.F. Tseluyko. PIG charged particle source with hydrogen supply from a metal-hydride cathode // J. Phys. Conf. Ser. 2014, v. 514, p. 012051. 4. I. Sereda, A. Tseluyko, D. Ryabchikov, Ya. Hrechko, N. Azarenkov. Effect of metal-hydride hydrogen activa- tion on longitudinal yield of negative ions from PIG // In- ternational Journal of Hydrogen Energy. 2017, v. 42/34, p. 21866-21870. 5. I.N. Sereda, A.F. Tseluyko, D.L. Ryabchikov, Ya.O. Hrechko, A. Krupka. Electromagnetic filter for H– separation from PIG with metal hydride cathode // Problems of Atomic Sci. and Tech. Series «Plasma Elec- tronics and New Methods of Acceleration» (116). 2018, № 4, p. 282-284. 6. Brown Ian G. The physics and technology of ion sources / John Wiley & Sons: «New York», 1989, p. 85-87. 7. I.N. Sereda, Ya.O. Hrechko, D.L. Ryabchikov, A.F. Tseluyko, N.A. Azarenkov. The increasing of H – cur- rent from Penning ion source with electrically biased metal hydride cathode // Vacuum. 2019, v. 162, p. 163-167. Article received 28.09.2020 ОСОБЕННОСТИ РАБОТЫ ЭЛЕКТРОМАГНИТНОГО ФИЛЬТРА В ПЕННИНГОВСКОМ ИСТОЧНИКЕ С МЕТАЛЛОГИДРИДНЫМ КАТОДОМ И. Середа, Я. Гречко, Е. Бабенко, А. Кашаба Описан метод сепарации отрицательных ионов водорода из аксиального потока заряженных частиц, вы- ходящих из разряда Пеннинга с металлогидридным катодом. С этой целью на основе численного решения уравнения движения заряженных частиц разработан электромагнитный фильтр. Определены оптимальные параметры работы фильтра для эффективной регистрации отрицательных ионов водорода, выходящих в аксиальном направлении. Проделанные расчеты вместе с экспериментальной проверкой показали, что не более 10% электронов содержится в регистрируемом токе отрицательных ионов водорода. Данная модель может быть применена для интерпретации любых экспериментов по сепарации ионов H – из аксиального потока заряженных частиц, извлекаемых из источника с цилиндрической геометрией. ОСОБЛИВОСТІ РОБОТИ ЕЛЕКТРОМАГНІТНОГО ФІЛЬТРА В ПЕННІНГОВСЬКОМУ ДЖЕРЕЛІ З МЕТАЛОГІДРИДНИМ КАТОДОМ І. Середа, Я. Гречко, Є. Бабенко, А. Кашаба Описаний метод сепарації негативних іонів водню з аксіального потоку заряджених частинок, що вихо- дять із розряду Пеннінга з металогідридним катодом. З цією метою на основі чисельного рішення рівняння руху заряджених частинок був розроблений електромагнітний фільтр. Визначено оптимальні параметри ро- боти фільтра для ефективної реєстрації негативних іонів водню, що виходять в аксіальному напрямку. Зроб- лені розрахунки разом з експериментальною перевіркою показали, що не більше 10% електронів реєстру- ються в струмі негативних іонів водню. Ця модель може бути застосована для інтерпретації будь-яких екс- периментів по сепарації іонів H – з аксіального потоку заряджених частинок, що витягаються з джерела, що має циліндричну геометрію.

Peculiarities of electromagnetic filter operation in penning source with metal hydride cathode

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