Potential Designs of High Power Degenerate Band Edge Oscillator (DBEO) for Hot Test at UNM and MIT Mohamed Othman 1 , Alex Figotin 2 , Filippo Capolino 1 1 March 03, 2017 1 Department of Electrical Engineering and Computer Science, UCI 2 Department of Mathematics, UCI MURI Teleconference, March 2017
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Potential Designs of High Power Degenerate Band Edge Oscillator (DBEO) for Hot Test at UNM and MIT
Mohamed Othman1, Alex Figotin2 , Filippo Capolino1
1March 03, 2017
1Department of Electrical Engineering and Computer Science, UCI
2Department of Mathematics, UCI
MURI Teleconference, March 2017
I. Degenerate band edge (DBE) in slow-wave structures (SWSs)
II. Degenerate band edge oscillator (DBEO)
III. A number of potential designs for experimental hot test
- Design 1. High power DBEO, compatible with UNM setup
• 12 ns e-beam pulse, ~160 MW pulsed output power
- Design 2. High power DBEO, compatible with MIT setup
• Long e-beam pulse, ~20 MW output power
IV. Conclusion
Outline
2
Degenerate band edge (DBE)
Waveguide structures can support a DBE, instead of only an RBE (regular
band edge). At DBE, we have four degenerate modes
4
DBE dispersion d dk k Periodic slow wave structure (SWS)
‒ A unit cell consisting of circular waveguide loaded with two irises
‒ The iris is formed by two complementary split rings
‒ There is misalignment angle between the split rings
• DBE frequency ~ 3.8 GHz
• Mode distribution has a strong Ez component synchronous to the e-beam
PIC simulations are done using CST Particle Studio 2016
y
z
Ez
8
Dispersion of the DBE mode for various
misalignment angles
1. Plan for hot test at UNM
UNM parameter
setupValue
Beam current Up to 6 kA
Beam voltage Up to 600 kV
Cathode outer
radius10 mm annular
Magnetic field Up to 1.5 T
Beam pulse 12 ns
Maximum SWS
length350 mm (9 solenoids)
Maximum radius 25 mm max
Output waveguideHorn antenna and
windowe-
bea
m p
uls
e sh
ape
Benford, Swegle, Schamiloglu, High power microwaves,
CRC Press, 2015
Photo courtesy of
UNM
E. Schamiloglu,
S. Yurt
UNM set up
‒ All critical parameters are
accommodated in our design
9
Optimized DBEO for UNM experimental setup
TM mode
SWS length 290 mm
Total length
including horn450 mm
horn radius 75 mm
Waveguide
radius25 mm
Magnetic field Up to 1.5 T
Beam voltage 500 kV
Beam current Up to 5 kA
Window (output port)
Circular horn
290 mm
cathode
150 mm
450 mm
50 mm
Simulation parameters
N =16 unit cells240 mm
10
PIC simulation resultse-
bea
m p
uls
e sh
ape
Round trip time ~ 3 ns
UNM SINUS-6 e-beam pulse
Round trip RF signal path
e-
Outp
ut
RF
pow
er [
MW
]
11
e-b
eam
cu
rren
t [A
]
Tunability of the DBEO
A coaxial extraction scheme may
be used to aid the extraction of
power (similar to UNM* design)
Misalignment angle between rings can
be used to tune the output power
• During cold test we will show the tunability of the response
Tunability range of output
power
Beam collection tube
*Kevin Shipman, Experimental Plan for Testing the UNM Metamaterial Slow Wave Structure for High Power Microwave Generation, MURI Teleseminar August 5, 2016.
12
Beam tunnel
Distribution of Ez in the DBEO
Field profile shows some hot spots
of fields between the rings‒ Breakdown investigating (in