A key parameter for the gyrotron operation and efficiency is the presence of trapped electrons. Two electron trapping mechanisms can take place in gyrotrons: (i) the adiabatic trap and (ii) the magnetic potential well. Their influence on the gyrotron operation is analyzed. Two gun design criteria are then proposed to suppress both mechanisms in order to minimize the risk of possible problems. Experimental results of three high power gyrotrons are presented and their performance is correlated to the presence of populations of trapped electrons. Finally, some very general gun design principles are presented for the limitation of harmful electron trapping.
References
1.
I. Gr.
Pagonakis
and J. L.
Vomvoridis
, “The self-consistent 3D trajectory electrostatic code Ariadne for gyrotron beam tunnel simulation
,” in Joint 29th International Conference on Infrared and Millimeter Waves IRMMW and 12th International Conference on Terahertz Electronics
, Karlsruhe, Germany, 27 September-1 October (2004
), p. 657
.2.
S.
Illy
, J.
Zhang
, and J.
Jelonnek
, “Gyrotron electron gun and collector simulation with the ESRAY beam optics code
,” in 16th International Vacuum Electronics Conference (IVEC)
, Beijing, China, 27–29 April (2015
), P1.1.3.
T. M.
Tran
, D. R.
Whaley
, S.
Merazzi
, and R.
Gruber
, “DAPHNE, a 2D axisymmetric electron gun simulation code
,” in 6th Joint EPS-APS International Conference on Physics Computing
, Lugano, Switzerland, 22–26 August (1994
), p. 491
.4.
W. B.
Herrmannsfeldt
, “EGUN—An electron optics and gun design program
,” in SLAC, Stanford, California
(1988
).5.
B.
Piosczyk
, G.
Dammertz
, O.
Dumbrajs
, M. V.
Kertikeyan
, M. K.
Thumm
, and X.
Yang
, “165-GHz coaxial cavity gyrotron
,” IEEE Trans. Plasma Sci.
32
, 853
(2004
).6.
J. P.
Hogge
, T. P.
Goodman
, S.
Alberti
, F.
Albajar
, K. A.
Avramides
, P.
Benin
, S.
Bethuys
, W.
Bin
, T.
Bonicelli
, A.
Bruschi
, S.
Cirant
, E.
Droz
, O.
Dumbrajs
, D.
Fasel
, F.
Gandini
, G.
Gantenbein
, S.
Illy
, S.
Jawla
, J.
Jin
, S.
Kern
, P.
Lavanchy
, C.
Lievin
, B.
Marletaz
, P.
Marmillod
, A.
Perez
, B.
Piosczyk
, I.
Pagonakis
, L.
Porte
, T.
Rzesnicki
, U.
Siravo
, M.
Thumm
, and M. Q.
Tran
, “First experimental results from the European Union 2-MW coaxial cavity ITER gyrotron prototype
,” Fusion Sci. Technol.
55
, 204
(2009
).7.
S.
Cauffman
, M.
Blank
, Ph.
Borchard
, and K.
Felch
, “Overview of fusion gyrotron development programs at 110 GHz, 117.5 GHz, 140 GHz, and 170 GHz
,” in 38th International Conference on Infrared, Millimeter and Terahertz Waves (IRMMW-THz)
, Mainz on the Rhine, Germany, 1–6 September (2013
), Mo 1-1.8.
R.
Pu
, G. S.
Nusinovich
, O. V.
Sinitsyn
, and T. M.
Antonsen
, Jr., “Effect of the thickness of electron beams on the gyrotron efficiency
,” Phys. Plasmas
17
, 83105
(2010
).9.
A.
Schlaich
, C.
Wu
, I.
Gr. Pagonakis
, K.
Avramidis
, S.
Illy
, G.
Gantenbein
, J.
Jelonnek
, and M.
Thumm
, “Frequency-based investigation of charge neutralization processes and thermal cavity expansion in gyrotrons
,” J. Infrared Millim. THz Waves
36
, 797
(2015
).10.
Sh. E.
Tsimring
, Electron Beams and Microwave Vacuum Electronics
(John Wiley & Sons, Inc.
, Hoboken, New Jersey
, 2007
).11.
O. I.
Louksha
, G. G.
Sominski
, and D. V.
Kas'yanenko
, “Experimental study and numerical simulation of electron beam in gyrotron-type electron-optical system
,” in Proceedings of International University Conference on “Electronics and Radiophysics of Ultra-High Frequencies,”
St. Petersburg, Russia, 24–28 May (1999
), p. 130.12.
V. N.
Manuilov
, “Numerical simulation of low-frequency oscillations of the space charge and potential in the electron-optical system of a gyrotron
,” Radiophys. Quantum Electron.
49
, 786
(2006
).13.
A. N.
Kuftin
, V. K.
Lygin
, V. N.
Manuilov
, B. V.
Raisky
, E. A.
Solujanova
, and Sh. E.
Tsimring
, “Theory of helical electron beams in gyrotrons
,” Int. J. Infrared Millim. THz Waves
14
, 783
(1993
).14.
Sh. E.
Tsimring
and V. E.
Zapevalov
, “Experimental study of intense helical electron beams with trapped electrons
,” Int. J. Electron.
81
, 199
(1996
).15.
V. N.
Manuilov
and S. A.
Polushkin
, “Behavior of helical electron beams in gyrotrons with high pitch factors
,” Radiophys. Quantum Electron.
52
, 714
(2009
).16.
M. A.
Furman
and M. T. F.
Pivi
, “Probabilistic model for the simulation of secondary electron emission
,” Phys. Rev. ST Accel. Beams
5
, 124404
(2002
).17.
A.
Shih
and C.
Hor
, “Secondary emission properties as a function of the electron incidence angle
,” IEEE Trans. Electron Devices
40
, 824
–829
(1993
).18.
G. A.
Harrower
, “Energy spectra of secondary electrons from Mo and W for low primary energies
,” Phys. Rev.
104
, 52
(1956
).19.
H.
Bruining
, Physics and Applications of Secondary Electron Emission
(Pergamon Press, McGraw-Hill Book Co.
, New York
, 1954
).20.
B.
Piosczyk
, C.
Iatrou
, G.
Dammertz
, and M.
Thumm
, “Single-stage depressed collectors for gyrotrons
,” IEEE Trans. Plasma Sci.
24
, 579
(1996
).21.
K.
Sakamoto
, M.
Tsuneoka
, A.
Kasugai
, T.
Imai
, T.
Kariya
, K.
Hayashi
, and Y.
Mitsunaka
, “Major improvement of gyrotron efficiency with beam energy recovery
,” Phys. Rev. Lett.
73
, 3532
(1994
).22.
Y.
Itikawa
, “Cross sections for electron collisions with nitrogen molecules
,” J. Phys. Chemi. Ref. Data
35
, 31
(2006
).23.
I. Gr.
Pagonakis
, J.-P.
Hogge
, T.
Goodman
, S.
Alberti
, B.
Piosczyk
, S.
Illy
, T.
Rzesnicki
, S.
Kern
, and C.
Lievin
, “Gun design criteria for the refurbishment of the first prototype of the EU 170 GHz/2 MW/CW coaxial cavity gyrotron for ITER
,” in 34th International Conference on Infrared, Millimeter and Terahertz Wave (IRMMW-THz)
, Busan, Korea, 21–25 September (2009
).24.
I. Gr.
Pagonakis
, J.-P.
Hogge
, S.
Alberti
, S.
Illy
, B.
Piosczyk
, S.
Kern
, C.
Lievin
, and M. Q.
Tran
, “Status of the EU 170 GHz/2 MW/CW coaxial cavity gyrotron for ITER: The dummy gun experiment
,” in 35th International Conference on Infrared Millimeter and Terahertz Waves (IRMMW-THz)
, Rome, Italy, 5–10 September (2010
).25.
T.
Rzesnicki
, I. Gr.
Pagonakis
, A.
Samartsev
, K.
Avramidis
, G.
Gantenbein
, S.
Illy
, J.
Jelonnek
, J.
Jin
, C.
Lechte
, M.
Losert
, B.
Piosczyk
, M.
Thumm
, and EGYC Team
, “Recent experimental results of the European 1 MW, 170 GHz short-pulse gyrotron prototype for ITER
,” in 40th International Conference on Infrared, Millimeter, and Terahertz Waves (IRMMW-THz)
, Hong Kong, China, 23–28 August (2015
).26.
I.
Gr. Pagonakis
, F.
Albajar
, S.
Alberti
, K.
Avramidis
, T.
Bonicelli
, F.
Braunmueller
, A.
Bruschi
, I.
Chelis
, F.
Cismondi
, G.
Gantenbein
, V.
Hermann
, K.
Hesch
, J.-P.
Hogge
, J.
Jelonnek
, J.
Jin
, S.
Illy
, Z.
Ioannidis
, T.
Kobarg
, G.
Latsas
, F.
Legrand
, M.
Lontano
, B.
Piosczyk
, Y.
Rozier
, T.
Rzesnicki
, C.
Schlatter
, M.
Thumm
, I.
Tigelis
, M. Q.
Tran
, T.-M.
Tran
, J.
Weggen
, and J. L.
Vomvoridis
, “Status of the development of the EU 170 GHz/1 MW/CW gyrotron
,” Fusion Eng. Des.
96–97
, 149
–154
(2015
).27.
S.
Kern
, J.-P.
Hogge
, S.
Alberti
, K.
Avramides
, G.
Gantenbein
, S.
Illy
, J.
Jelonnek
, J.
Jin
, F.
Li
, I. Gr.
Pagonakis
, B.
Piosczyk
, T.
Rzesnicki
, M. K.
Thumm
, I.
Tigelis
, M. Q.
Tran
, and the Whole EU Home Team at EGYC
, “Experimental results and recent developments on the EU 2 MW 170 GHz coaxial cavity gyrotron for ITER
,” in 17th Joint Workshop on Electron Cyclotron Emission and Electron Cyclotron Resonance Heating, Deurne
, The Netherlands, 7–11 May (2012
).28.
K. A.
Avramidis
, I. Gr.
Pagonakis
, Z. C.
Ioannidis
, and I. G.
Tigelis
, “Numerical investigations on the effects of electron beam misalignment on beam-wave interaction in a high-power coaxial gyrotron
,” in 38th International Conference on Infrared, Millimeter, and Terahertz Waves (IRMMW-THz)
, Mainz, Germany, 14–19 September (2013
).29.
M.
Yu. Glyavin
, A. D.
Kuntsevich
, and V. N.
Manuilov
, “Suppression of the oscillatory modes of a space charge in the magnetron injection guns of technological gyrotrons
,” J. Infrared Millim. THz Waves
36
, 7
(2015
).30.
S.
Ruess
, I. Gr.
Pagonakis
, T.
Rzesnicki
, G.
Gantenbein
, S.
Illy
, M.
Thumm
, and J.
Jelonnek
, “A design proposal for an optimized inverse magnetron injection gun for the KIT 2 MW/170 GHz modular coaxial cavity gyrotron
,” in 16th International Vacuum Electronics Conference (IVEC)
, Beijing, China, 27–29 April (2015
), S4.1.31.
T.
Rzesnicki
, G.
Gantenbein
, J.
Jelonnek
, J.
Jin
, I. Gr.
Pagonakis
, B.
Piosczyk
, A.
Samartsev
, A.
Schlaich
, and M.
Thumm
, “2 MW, 170 GHz coaxial-cavity short-pulse gyrotron—Single stage depressed collector operation
,” in 39th International Conference on Infrared, Millimeter and THz Waves (IRMMW-THz)
, Tucson, AZ, USA, 14–19 September (2014
), W4/D5.32.
J.
Franck
, I. Gr.
Pagonakis
, K. A.
Avramidis
, G.
Gantenbein
, S.
Illy
, M.
Thumm
, and J.
Jelonnek
, “Magnetron injection gun for a 238 GHz 2 MW coaxial-cavity gyrotron
,” in 9th German Microwave Conference (GeMiC)
, Nürnberg, Germany, 16–18 March (2015
), p. 260
.© 2016 EURATOM.
2016
EURATOM
You do not currently have access to this content.