Multistage Depressed Collectors (MDCs) are nontrivial for high-frequency gyrotrons. A basic conceptual design of an E×B MDC using azimuthal electric fields was proposed in Part I of this series. In the present work, several upgraded design proposals based on the basic one will be elaborated. These proposals will significantly reduce the back-stream of electrons, which was the main drawback of the basic design proposal. Another upgraded design proposal will shrink the length and maximal radius of the MDC to be only a fraction of its full-length version. A conceptual design of the final MDC proposal will be given at the end.

1.
J.
Jelonnek
,
G.
Aiello
,
S.
Alberti
,
K.
Avramidis
,
F.
Braunmueller
,
A.
Bruschi
,
J.
Chelis
,
J.
Franck
,
T.
Franke
,
G.
Gantenbein
,
S.
Garavaglia
,
G.
Granucci
,
G.
Grossetti
,
S.
Illy
,
Z. C.
Ioannidis
,
J.
Jin
,
P.
Kalaria
,
G. P.
Latsas
,
I. G.
Pagonakis
,
T.
Rzesnicki
,
S.
Ruess
,
T.
Scherer
,
M.
Schmid
,
D.
Strauss
,
C.
Wu
,
I.
Tigelis
,
M.
Thumm
, and
M. Q.
Tran
, “
Design considerations for future DEMO gyrotrons: A review on related gyrotron activities within EUROfusion
,”
Fusion Eng. Des.
123
,
241
246
(
2017
).
2.
M. E.
Read
,
W. G.
Lawson
,
A. J.
Dudas
, and
A.
Singh
, “
Depressed collectors for high-power gyrotrons
,”
IEEE Trans. Electron Devices
37
,
1579
1589
(
1990
).
3.
A.
Singh
,
G.
Hazel
,
V. L.
Granatstein
, and
G.
Saraph
, “
Magnetic field profiles in depressed collector region for small-orbit gyrotrons with axial or radially extracted spent beam
,”
Int. J. Electron.
72
,
1153
1163
(
1992
).
4.
A.
Singh
,
S.
Rajapatirana
,
Y.
Men
,
V. L.
Granatstein
,
R. L.
Ives
, and
A. J.
Antolak
, “
Design of a multistage depressed collector system for 1-MW CW gyrotrons. I. trajectory control of primary and secondary electrons in a two-stage depressed collector
,”
IEEE Trans. Plasma Sci.
27
,
490
502
(
1999
).
5.
I. G.
Pagonakis
,
J. P.
Hogge
,
S.
Alberti
,
K. A.
Avramides
, and
J. L.
Vomvoridis
, “
A new concept for the collection of an electron beam configured by an externally applied axial magnetic field
,”
IEEE Trans. Plasma Sci.
36
,
469
480
(
2008
).
6.
O. I.
Louksha
and
P. A.
Trofimov
, “
A method of electron separation for multistep recuperation systems in gyrotrons
,”
Tech. Phys. Lett.
41
,
884
886
(
2015
).
7.
I. G.
Pagonakis
,
C.
Wu
,
S.
Illy
, and
J.
Jelonnek
, “
Multistage depressed collector conceptual design for thin magnetically confined electron beams
,”
Phys. Plasmas
23
,
043114
(
2016
).
8.
C.
Wu
,
I. G.
Pagonakis
,
G.
Gantenbein
,
S.
Illy
,
M.
Thumm
, and
J.
Jelonnek
, “
Conceptual designs of E×B multistage depressed collectors for gyrotrons
,”
Phys. Plasmas
24
,
043102
(
2017
).
9.
C.
Wu
,
I. G.
Pagonakis
,
S.
Illy
,
G.
Gantenbein
,
M.
Thumm
, and
J.
Jelonnek
, “
Novel multistage depressed collector for high power fusion gyrotrons based on an E×B drift concept
,” in
Proceedings of the International Vacuum Electronics Conference (IVEC)
(
2017
), pp.
1
2
.
10.
C.
Wu
,
I. G.
Pagonakis
,
G.
Gantenbein
,
S.
Illy
,
M.
Thumm
, and
J.
Jelonnek
, “
Design of E×B multistage depressed collector concepts for high-power fusion gyrotrons
,” in
42nd International Conference on Infrared, Millimeter, and Terahertz Waves (IRMMW-THz)
(
IEEE
,
2017
), pp.
1
2
.
11.
C.
Wu
,
I. G.
Pagonakis
,
K. A.
Avramidis
,
G.
Gantenbein
,
S.
Illy
,
M.
Thumm
, and
J.
Jelonnek
, “
Gyrotron multistage depressed collector based on E×B drift concept using azimuthal electric field. I. basic design
,”
Phys. Plasmas
25
,
033108
(
2018
).
12.
T.
Rzesnicki
,
F.
Albajar
,
S.
Alberti
,
K. A.
Avramidis
,
W.
Bin
,
T.
Bonicelli
,
F.
Braunmueller
,
A.
Bruschi
,
J.
Chelis
,
P.-E.
Frigot
,
G.
Gantenbein
,
V.
Hermann
,
J.-P.
Hogge
,
S.
Illy
,
Z. C.
Ioannidis
,
J.
Jin
,
J.
Jelonnek
,
W.
Kasparek
,
G. P.
Latsas
,
C.
Lechte
,
M.
Lontano
,
T.
Kobarg
,
I. G.
Pagonakis
,
Y.
Rozier
,
C.
Schlatter
,
M.
Schmid
,
I. G.
Tigelis
,
M.
Thumm
,
M. Q.
Tran
,
J. L.
Vomvoridis
, and
A.
Zisis
, “
Experimental verification of the European 1 MW, 170 GHz industrial CW prototype gyrotron for ITER
,”
Fusion Eng. Des.
123
,
490
494
(
2017
).
13.
K. A.
Avramides
,
I. G.
Pagonakis
,
C. T.
Iatrou
, and
J. L.
Vomvoridis
, “
EURIDICE: A code-package for gyrotron interaction simulations and cavity design
,” in
European Physical Journal Web of Conferences
(
2012
), Vol.
32
, p.
04016
.
14.
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
3535
(
1994
).
15.
B.
Piosczyk
,
C. T.
Iatrou
,
G.
Dammertz
, and
M.
Thumm
, “
Single-stage depressed collectors for gyrotrons
,”
IEEE Trans. Plasma Sci.
24
,
579
585
(
1996
).
16.
M. A.
Furman
and
M. T.
Pivi
, “
Probabilistic model for the simulation of secondary electron emission
,”
Phys. Rev. Spec. Top. Accel. Beams
5
,
124404
(
2002
).
17.
M. E.
Read
,
A. J.
Dudas
,
J. J.
Petillo
, and
M. Q.
Tran
, “
Design and testing of an electron gun producing a segmented sheet beam for a quasi-optical gyrotron
,”
IEEE Trans. Electron Devices
39
,
720
726
(
1992
).
18.
A.
Malygin
,
S.
Illy
,
I. G.
Pagonakis
,
B.
Piosczyk
,
S.
Kern
,
J.
Weggen
,
M.
Thumm
,
J.
Jelonnek
,
K. A.
Avramides
,
R. L.
Ives
,
D.
Marsden
, and
G.
Collins
, “
Design and 3-D simulations of a 10-kW/28-GHz gyrotron with a segmented emitter based on controlled porosity-reservoir cathodes
,”
IEEE Trans. Plasma Sci.
41
,
2717
2723
(
2013
).
You do not currently have access to this content.