Electrodynamics in e⁻ linacs

We report a new calculation of electron beam acceleration along linac using fundamental electrodynamics as basis. Following laws are considered: increasing of work equals multiplication of force to elementary interval; power equals work growth over time interval; force acting on charge equals charge...

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Veröffentlicht in:Вопросы атомной науки и техники
Datum:2014
Hauptverfasser: Proskin, S.S., Dvornikov, V.A., Kuzmin, I.A., Shchedrin, I.S.
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Veröffentlicht: Національний науковий центр «Харківський фізико-технічний інститут» НАН України 2014
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Zitieren:Electrodynamics in e⁻ linacs / S.S. Proskin, V.A. Dvornikov, I.A. Kuzmin, I.S. Shchedrin // Вопросы атомной науки и техники. — 2014. — № 5. — С. 136-139. — Бібліогр.: 7 назв. — англ.

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Digital Library of Periodicals of National Academy of Sciences of Ukraine
_version_ 1860115848986886144
author Proskin, S.S.
Dvornikov, V.A.
Kuzmin, I.A.
Shchedrin, I.S.
author_facet Proskin, S.S.
Dvornikov, V.A.
Kuzmin, I.A.
Shchedrin, I.S.
citation_txt Electrodynamics in e⁻ linacs / S.S. Proskin, V.A. Dvornikov, I.A. Kuzmin, I.S. Shchedrin // Вопросы атомной науки и техники. — 2014. — № 5. — С. 136-139. — Бібліогр.: 7 назв. — англ.
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container_title Вопросы атомной науки и техники
description We report a new calculation of electron beam acceleration along linac using fundamental electrodynamics as basis. Following laws are considered: increasing of work equals multiplication of force to elementary interval; power equals work growth over time interval; force acting on charge equals charge value multiplied to electric field value. Using electrodynamic characteristic, series impedance, equaled a square of electric eld value divided by power, and also taking into account laws mentioned above, an equation for the electric field radiated by the beam is calculated. A transient process of electric field radiated by beam is considered. Рассмотрен расчет ускорения сгустков в линейных ускорителях электронов, основанный на постулатах электродинамики. Перечислены основные постулаты: увеличение работы равно произведению силы на элемент пройденного расстояния; мгновенная мощность равна отношению прироста работы на отрезок времени; сила, действующая на заряд, равна величине заряда, умноженного на напряженность электрического поля. Используя электродинамическую характеристику, последовательное сопротивление круглого диафрагмированного волновода, равное отношению квадрата напряженности электрического поля к мгновенной мощности, и выше названные постулаты электродинамики, получено выражение для электрического поля излучения. Рассмотрен переходный процесс поля излучения цуга сгустков. Розглянуто розрахунок прискорення згусткiв у лiнiйних прискорювачах електронiв, оснований на постулатах електродинамiки. Перелiченi основнi постулати: збiльшення роботи дорiвнює здобутку сили на елемент пройденої вiдстанi; миттєва потужнiсть дорiвнює вiдношенню приросту роботи на вiдрiзок часу; сила, дiюча на заряд, рiвна величинi заряду, помноженого на напруженiсть электричного поля. Використовуючи електродинамiчну характеристику, послiдовний опiр круглого дiафрагмованого хвильопровода, який дорiвнює вiдношеннию квадрата напруженостi електричного поля на миттєву потужнiсть, та перелiченi вище постулати електродинамiки, отриманоно вираз для електричного поля випромiнювання. Розглянуто перехiдний процес поля випромiнювання цуга сгусткiв.
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fulltext THEORY AND TECHNICS OF PARTICLE ACCELERATION ELECTRODYNAMICS IN e− LINACS S.S.Proskin, V.A.Dvornikov, I.A.Kuzmin, I. S. Shchedrin∗ National Research Nuclear University MEPhI, Moscow, Russia (Received September 26, 2013) We report a new calculation of electron beam acceleration along linac using fundamental electrodynamics as basis. Following laws are considered: increasing of work equals multiplication of force to elementary interval; power equals work growth over time interval; force acting on charge equals charge value multiplied to electric field value. Using electrodynamic characteristic, series impedance, equaled a square of electric field value divided by power, and also taking into account laws mentioned above, an equation for the electric field radiated by the beam is calculated. A transient process of electric field radiated by beam is considered. PACS: 29.27.-a 1. MAIN REMARKS ON TRAVELLING WAVE ELECTRON LINAC THEORY Considering electron bunch acceleration in travelling wave acceleration structure few remarks on classical theory describing bunch movement along acceleration structure should be given [1]. In the first, the equation stated below is of great importance in order to obtain electric field radiated by moving along DLWG charge: dW = −qEdz , (1) dP dz = − ωP vgQ = −2αP , (2) dE dz = −αE . (3) Here dW is accelerated particle energy gain due travelling dz distance along waveguide axis, q is charge quantity, E is on-axis electric field amplitude, α is attenuation factor, vg is group velocity, P is in- stantaneous power and Q is disk loaded waveguide (DLWG) Q-factor. It should be stated also that equations (2)-(3) described by Perry B. Wilson are correct for DLWG feeding by RF power source in steady mode. It is wrong to believe that current en- ergy speed equals group velocity. But actually group velocity is responsible for transient mode and power source current energy speed equals bunch velocity. A relation mentioned by Wilson is series resis- tance Rp which plays important part too (further Rsh is shunt impedance): Rp = αRsh = ωRsh 2vgQ , (4) Rp = E2 2P . (5) In the next equation minus sign should be put be- fore multiplication of direct current and beam field: dP dz = I0Eb − 2αP . (6) It is considered that there is no power feed. En- ergy balance in the whole accelerating structure gives (6). Eb is beam field which resists short bunch with I0 current. Energy gain generated by beam is power loss. The next equation means beam generates 2 waves. The second component is in antiphase, i.e. in power source phase and attenuating as well as power source field: Eb(z) = I0Rsh(1− e−αz) . (7) It contradicts physics of the process. Moreover boundary conditions are failed when z = 0 for bridged waveguide. It is cleared that fundamental theory of beam loading which states that charge energy loss due radi- ation equals half of induced voltage gives simple way of beam field calculation. 2. BEAM FIELD CALCULATION BASED ON WILSON AND RAMO THEOREMS We consider a new approach to define relativistic elec- tron beam field in DLWG. Relativistic electron bunch with q charge is travelling along DLWG axis with con- stant β = v/c = 1 velocity. It is assumed that charge velocity is equaled to the speed of light. According to Perry B. Wilson theorem, W , energy being lost by travelling bunch with q charge, equals half of charge and induced voltage U multiplication [1]: W = 1 2 qU . (8) Assume that U voltage induced on x length equals current induced by q charge and multiplied by equiv- alent impedance R on accelerating gap x length. U = IR . (9) ∗Corresponding author E-mail address: ISShchedrin@mephi.ru, qstpss@gmail.com, +7(499)324-80-33 136 ISSN 1562-6016. PROBLEMS OF ATOMIC SCIENCE AND TECHNOLOGY, 2014, N5 (93). Series: Nuclear Physics Investigations (63), p.136-139. According to Simon Ramo theorem induced cur- rent equals multiplication of charge and velocity di- vided by gap length [2]: I = qc x . (10) Define R impedance on x gap length by means of series resistance Rp: R = Rpx 2 . (11) According to definition: Rp = E2 2P . (12) In the last equation E is electric field strength on DLWG axis, P is RF power in current DLWG cross- section. Using (8)-(12) for W , U , I, R and Rs, obtain beam energy loss gain W on DLWG x length: W = 1 2 qU = 1 2 q2cRpx . (13) Dissipated power equals: P = W t = 1 2 q2cRp x t . (14) Within considered case beam velocity equals the speed of light, i.e. x/t = c P = 1 2 q2c2Rp = E2 2Rp . (15) Which means that: .E = qcRp (16) Therefore, field E radiated by beam with q charge is defined by charge, velocity and DLWG series resis- tance. Current statement is also correct for velocities under the speed of light v < c, i.e. it is correct for any velocity of accelerating beam. E = qvRp . (17) 3. ELECTRON BEAM FIELD CALCULATION IN DLWG. CLASSICAL THEORY As it is expected simple calculation could raise doubts. That is why consider classical approach by means of electrodynamics fundamentals. Calculate q charge beam field on DLWG axis. Beam is travelling with v velocity. Point charge is considered. When travelling beam interacts with decelerating system like DLWG F force will act on charge. Force equals multiplication of q charge on E beam field. F = qE . (18) Instantaneous power equals differential relation of work dA divided by time interval dt, i.e.: P = dA dt . (19) It should be noted that force equals relation dA to dl, where dl is elementary distance on DLWG axis. F = dA dl . (20) (19)-(20) conclude that instantaneous power equals multiplication of force to velocity: P = F dl dt = Fv . (21) Substitute F from (18) to (21) and get: P = qEv . (22) Define average power in DLWG P̄ by means of E beam field and Rs series resistance: P̄ = E2 2Rp . (23) While reminding that electromagnetic field in- stantaneous power P and average P̄ differ by factor 2, get the next relation: P = 2P̄ , (24) P = E2 p . (25) (22) and (25) infer E = qRpv . (26) It is assumed indirectly that we have point charge bunch with q charge, v velocity on TM010 mode in DLWG. When v ̸= c (26) could be rewritten as: E = qRpβc . (27) In the current equation β = v/c and when β = 1 get: E = qRpc . (28) (28) could be rewritten also as follows. Since the speed of light equals wave length λ divided by oscil- lation period it is: c = λ T , (29) q T = I . (30) I is average q charge bunch current. Time be- tween bunches is equaled to oscillation period of RF power. Substitute (29), (30) to (28). As a result beam field in relativistic case (β = 1) equals: E = IRpλ . (31) For v ̸= c: E = IRpβλ . (32) (32) might be used for calculation of electron linac bunchers. (31) is usually used for calculation of elec- tron linac acceleration sections. Therefore, obviously equation (28) for obtain- ing single bunch field in travelling wave accelerat- ing structure calculated by means of classical theory identical with (17) calculated by means of Wilson and Ramo theorems. 137 4. MULTIPLE BUNCHES BEAM FIELD TRANSIENT PROCESS IN DLWG Consider radiation process for a chain of electrons with q charge, interval λ which is equaled to wave length in DLWG (Fig.1). The first bunch radiates field: E = IRpλ . (33) It is taken into account that beam is relativistic (v = c) and interval between point charge bunches is equaled wave length λ. Using results of [3] and considering DLWG as chain of feedthrough quarter- wave cavities (θ = π/2 mode) or third-wave cavities (θ = 2π/3 mode) beam field E transient process is defined as: E1 = lRpλe − πt Q1T . (34) In the statement above t is current time, T is oscillations period and Q1 is DLWG loaded Q- factor. While t = 0: E1 = IRpλ. Fig.1. The chain of bunches travelling in DLWG When the second bunch enters considered DLWG cross-section beam field is: E2 = IRpλ+ IRpλe − π Ql . (35) And after the third bunch: E2 = IRpλ+ IRpλe − π Ql + IRpλe − 2π Ql . (36) Net series is a geometric sequence. Summary field in considered cross-section is equaled: En = IRpλ ( 1− e −nπ Ql ) 1− e − π Ql . (37) When infinite quantity of bunches is taken into calculation following beam field is observed in DLWG with finite Ql: E0 = IRpλ 1− e − π Ql . (38) Field envelope amplitude growth is obvi- ously characterized by Ql size (Fig. 2). Fig.2. Transient process for the chain of bunches beam field We take into account power losses in walls under T oscillation period. As it is seen from (37) maxi- mum field is generated after travelling of n bunches in DLWG cross-section. After the bunch number n beam field decreases according to law: E = IRpλ ( 1− e −nπ Ql ) 1− e − π Ql . (39) It should be mentioned that time is counted here before the bunch number n enters considered cross- section. 5. CONCLUSIONS As a result few remarks on classical theory for calcu- lation of electron linac electrodynamic parameters are given within current research. Method of beam field calculation based on electrodynamics fundamentals and different from classical one is proposed. Derived way of beam field calculation is used in consideration of transient process for the chain of bunches beam field. Moreover, this technique could be used not for DLWG only but for other electron linac accelerating structures which have their own benefits and draw- backs. Calculation of electron beam field presented within current work allows to make more accurate calculations of some electrodynamic characteristics used in design and optimization of electron linac ac- celerating systems including improvement of acceler- ating structures design software. Presented research has been conducted in realiza- tion of two State Contracts in Compact Accelerators Laboratory of National Research Nuclear University MEPhI which has been financed within mentioned contracts. It includes development of electron linac with 4MeV output energy (with usage of modern klystrons and magnetrons of different wave lengths) for generation of powerful bremmstrahlung in THz wavelength range and also development of linear elec- tron accelerator with 15MeV output energy, maxi- mum of 1 kA beam current and pulse duration about 1ns. 138 This work has been accomplished under support of The Ministry of Education and Science of The Rus- sian Federation within the program ”Science and ed- ucation of the innovative Russia” 2009− 2013, State Contracts P433, P1222, the program ”Developing of the High School science potential” 2009 − 2010, sci- entific work number 1.49.09 and also by State Order from The Ministry of Education and Science of The Russian Federation number N00− Γ− 611− 4056. References 1. P.B.Wilson. High Energy Electron Linacs// Ap- plications to Storage Ring RF Systems and Lin- ear Colliders. Stanford, California: SLAC-PUB- 2884, November 1991(A), 46 p. 2. S. Ramo. Currents Induced by Electron Motion // Proceedings of the I/R/E. September 1939, p. 584-585. 3. D.Altman. Microwave circuits / Translation from English by editorial board under supervis- ing of I.V. Lebedev. M: ”Mir”, 1968, 487 p. 4. O.A.Valdner, A.N.Didenko, A.V. Shalnov. Ac- celerating waveguides. M: ”Atomizdat”, 1973, 216 p. 5. A.P.Kulago, I.S. Shchedrin. Radiation of rel- ativistic bunches in DLWG // II Cherenkov readings: new methods in experimental nuclear physics of elementary particles. M: ”FIAN”, 2009, p. 48-56. 6. V.A.Dvornikov, I.A.Kuzmin, S.S. Proskin, et al. A study of physical processes describing extreme density charge bunches acceleration in DLWG with stored energy // Nuclear physics and engi- neering. M: MAIK ”Nauka/Interperiodika”, v. 2, N1, January-February 2011, p. 3-17. 7. S.S. Proskin, V.A.Dvornikov, I.A.Kuzmin, et al. Study of Physical Processes of Acceleration of Electron Bunches with Extreme Density by means of Stored Energy in Disk Loaded Waveg- uide Sections // Proceedings of IPAC 2012, New Orleans, Louisiana, USA. ÝËÅÊÒÐÎÄÈÍÀÌÈÊÀ  ËÈÍÅÉÍÛÕ ÓÑÊÎÐÈÒÅËßÕ ÝËÅÊÒÐÎÍΠÑ.Ñ.Ïðîñêèí, Â.À.Äâîðíèêîâ, È.À.Êóçüìèí, È.Ñ.Ùåäðèí Ðàññìîòðåí ðàñ÷åò óñêîðåíèÿ ñãóñòêîâ â ëèíåéíûõ óñêîðèòåëÿõ ýëåêòðîíîâ, îñíîâàííûé íà ïîñòóëàòàõ ýëåêòðîäèíàìèêè. Ïåðå÷èñëåíû îñíîâíûå ïîñòóëàòû: óâåëè÷åíèå ðàáîòû ðàâíî ïðîèçâåäåíèþ ñèëû íà ýëåìåíò ïðîéäåííîãî ðàññòîÿíèÿ; ìãíîâåííàÿ ìîùíîñòü ðàâíà îòíîøåíèþ ïðèðîñòà ðàáîòû íà îòðåçîê âðåìåíè; ñèëà, äåéñòâóþùàÿ íà çàðÿä, ðàâíà âåëè÷èíå çàðÿäà, óìíîæåííîãî íà íàïðÿæåííîñòü ýëåê- òðè÷åñêîãî ïîëÿ. Èñïîëüçóÿ ýëåêòðîäèíàìè÷åñêóþ õàðàêòåðèñòèêó, ïîñëåäîâàòåëüíîå ñîïðîòèâëåíèå êðóãëîãî äèàôðàãìèðîâàííîãî âîëíîâîäà, ðàâíîå îòíîøåíèþ êâàäðàòà íàïðÿæåííîñòè ýëåêòðè÷åñêîãî ïîëÿ ê ìãíîâåííîé ìîùíîñòè, è âûøå íàçâàííûå ïîñòóëàòû ýëåêòðîäèíàìèêè, ïîëó÷åíî âûðàæåíèå äëÿ ýëåêòðè÷åñêîãî ïîëÿ èçëó÷åíèÿ. Ðàññìîòðåí ïåðåõîäíûé ïðîöåññ ïîëÿ èçëó÷åíèÿ öóãà ñãóñòêîâ. ÅËÅÊÒÐÎÄÈÍÀÌIÊÀ  ËIÍIÉÍÈÕ ÏÐÈÑÊÎÐÞÂÀ×ÀÕ ÅËÅÊÒÐÎÍI Ñ.Ñ.Ïðîñêií, Â.À.Äâîðíiêîâ, I.À.Êóçüìií, I.Ñ.Ùåäðií Ðîçãëÿíóòî ðîçðàõóíîê ïðèñêîðåííÿ çãóñòêiâ ó ëiíiéíèõ ïðèñêîðþâà÷àõ åëåêòðîíiâ, îñíîâàíèé íà ïî- ñòóëàòàõ åëåêòðîäèíàìiêè. Ïåðåëi÷åíi îñíîâíi ïîñòóëàòè: çáiëüøåííÿ ðîáîòè äîðiâíþ¹ çäîáóòêó ñèëè íà åëåìåíò ïðîéäåíî¨ âiäñòàíi; ìèòò¹âà ïîòóæíiñòü äîðiâíþ¹ âiäíîøåííþ ïðèðîñòó ðîáîòè íà âiäði- çîê ÷àñó; ñèëà, äiþ÷à íà çàðÿä, ðiâíà âåëè÷èíi çàðÿäó, ïîìíîæåíîãî íà íàïðóæåíiñòü ýëåêòðè÷íîãî ïîëÿ. Âèêîðèñòîâóþ÷è åëåêòðîäèíàìi÷íó õàðàêòåðèñòèêó, ïîñëiäîâíèé îïið êðóãëîãî äiàôðàãìîâàíî- ãî õâèëüîïðîâîäà, ÿêèé äîðiâíþ¹ âiäíîøåííèþ êâàäðàòà íàïðóæåíîñòi åëåêòðè÷íîãî ïîëÿ íà ìèòò¹âó ïîòóæíiñòü, òà ïåðåëi÷åíi âèùå ïîñòóëàòè åëåêòðîäèíàìiêè, îòðèìàíîíî âèðàç äëÿ åëåêòðè÷íîãî ïîëÿ âèïðîìiíþâàííÿ. Ðîçãëÿíóòî ïåðåõiäíèé ïðîöåñ ïîëÿ âèïðîìiíþâàííÿ öóãà ñãóñòêiâ. 139
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institution Digital Library of Periodicals of National Academy of Sciences of Ukraine
issn 1562-6016
language English
last_indexed 2025-12-07T17:36:24Z
publishDate 2014
publisher Національний науковий центр «Харківський фізико-технічний інститут» НАН України
record_format dspace
spelling Proskin, S.S.
Dvornikov, V.A.
Kuzmin, I.A.
Shchedrin, I.S.
2015-04-18T15:13:54Z
2015-04-18T15:13:54Z
2014
Electrodynamics in e⁻ linacs / S.S. Proskin, V.A. Dvornikov, I.A. Kuzmin, I.S. Shchedrin // Вопросы атомной науки и техники. — 2014. — № 5. — С. 136-139. — Бібліогр.: 7 назв. — англ.
1562-6016
PACS: 29.27.-a
https://nasplib.isofts.kiev.ua/handle/123456789/80497
We report a new calculation of electron beam acceleration along linac using fundamental electrodynamics as basis. Following laws are considered: increasing of work equals multiplication of force to elementary interval; power equals work growth over time interval; force acting on charge equals charge value multiplied to electric field value. Using electrodynamic characteristic, series impedance, equaled a square of electric eld value divided by power, and also taking into account laws mentioned above, an equation for the electric field radiated by the beam is calculated. A transient process of electric field radiated by beam is considered.
Рассмотрен расчет ускорения сгустков в линейных ускорителях электронов, основанный на постулатах электродинамики. Перечислены основные постулаты: увеличение работы равно произведению силы на элемент пройденного расстояния; мгновенная мощность равна отношению прироста работы на отрезок времени; сила, действующая на заряд, равна величине заряда, умноженного на напряженность электрического поля. Используя электродинамическую характеристику, последовательное сопротивление круглого диафрагмированного волновода, равное отношению квадрата напряженности электрического поля к мгновенной мощности, и выше названные постулаты электродинамики, получено выражение для электрического поля излучения. Рассмотрен переходный процесс поля излучения цуга сгустков.
Розглянуто розрахунок прискорення згусткiв у лiнiйних прискорювачах електронiв, оснований на постулатах електродинамiки. Перелiченi основнi постулати: збiльшення роботи дорiвнює здобутку сили на елемент пройденої вiдстанi; миттєва потужнiсть дорiвнює вiдношенню приросту роботи на вiдрiзок часу; сила, дiюча на заряд, рiвна величинi заряду, помноженого на напруженiсть электричного поля. Використовуючи електродинамiчну характеристику, послiдовний опiр круглого дiафрагмованого хвильопровода, який дорiвнює вiдношеннию квадрата напруженостi електричного поля на миттєву потужнiсть, та перелiченi вище постулати електродинамiки, отриманоно вираз для електричного поля випромiнювання. Розглянуто перехiдний процес поля випромiнювання цуга сгусткiв.
This work has been accomplished under support&#xd; of The Ministry of Education and Science of The Russian&#xd; Federation within the program ”Science and education&#xd; of the innovative Russia” 2009 − 2013, State&#xd; Contracts P433, P1222, the program ”Developing of&#xd; the High School science potential” 2009 − 2010, scientific&#xd; work number 1.49.09 and also by State Order&#xd; from The Ministry of Education and Science of The&#xd; Russian Federation number N00 − Γ − 611 − 4056.
en
Національний науковий центр «Харківський фізико-технічний інститут» НАН України
Вопросы атомной науки и техники
Теория и техника ускорения частиц
Electrodynamics in e⁻ linacs
Электродинамика в линейных ускорителях электронов
Електродинамiка в лiнiйних прискорювачах електронiв
Article
published earlier
spellingShingle Electrodynamics in e⁻ linacs
Proskin, S.S.
Dvornikov, V.A.
Kuzmin, I.A.
Shchedrin, I.S.
Теория и техника ускорения частиц
title Electrodynamics in e⁻ linacs
title_alt Электродинамика в линейных ускорителях электронов
Електродинамiка в лiнiйних прискорювачах електронiв
title_full Electrodynamics in e⁻ linacs
title_fullStr Electrodynamics in e⁻ linacs
title_full_unstemmed Electrodynamics in e⁻ linacs
title_short Electrodynamics in e⁻ linacs
title_sort electrodynamics in e⁻ linacs
topic Теория и техника ускорения частиц
topic_facet Теория и техника ускорения частиц
url https://nasplib.isofts.kiev.ua/handle/123456789/80497
work_keys_str_mv AT proskinss electrodynamicsinelinacs
AT dvornikovva electrodynamicsinelinacs
AT kuzminia electrodynamicsinelinacs
AT shchedrinis electrodynamicsinelinacs
AT proskinss élektrodinamikavlineinyhuskoritelâhélektronov
AT dvornikovva élektrodinamikavlineinyhuskoritelâhélektronov
AT kuzminia élektrodinamikavlineinyhuskoritelâhélektronov
AT shchedrinis élektrodinamikavlineinyhuskoritelâhélektronov
AT proskinss elektrodinamikavliniinihpriskorûvačahelektroniv
AT dvornikovva elektrodinamikavliniinihpriskorûvačahelektroniv
AT kuzminia elektrodinamikavliniinihpriskorûvačahelektroniv
AT shchedrinis elektrodinamikavliniinihpriskorûvačahelektroniv