Theoretical study and PIC simulation of a 220 GHz Gyro-TWT with periodic dielectric loaded waveguide

Ru-Tai CHEN; Sheng YU

doi:10.11972/j.issn.1001-9014.2022.06.014

Journals >Journal of Infrared and Millimeter Waves >Volume 41 >Issue 6 >Page 1042 > Article

Journal of Infrared and Millimeter Waves
Vol. 41, Issue 6, 1042 (2022)

Theoretical study and PIC simulation of a 220 GHz Gyro-TWT with periodic dielectric loaded waveguide

Ru-Tai CHEN^* and Sheng YU

Author Affiliations

School of Electronic Science and Engineering，University of Electronic Science and Technology of China，Chengdu 611731，China

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DOI: 10.11972/j.issn.1001-9014.2022.06.014 Cite this Article

Ru-Tai CHEN, Sheng YU. Theoretical study and PIC simulation of a 220 GHz Gyro-TWT with periodic dielectric loaded waveguide[J]. Journal of Infrared and Millimeter Waves, 2022, 41(6): 1042 Copy Citation Text

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Fig. 1. Beam-wave interaction circuit configurations of the 220 GHz Gyro-TWT (a) The 3-D structure diagram, (b) the interaction circuit schematic

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Dispersion diagram of 220 GHz PDL Gyro-TWT，（U0=70 kV，beam velocity pitch factor α=1.2，magnetic detuning ratio b=0.98. Point A，B，C are backward wave oscillation points. The red circular area is convective instability area）

Fig. 2. Dispersion diagram of 220 GHz PDL Gyro-TWT，（

U_{0} = 70 k V

，beam velocity pitch factor

α = 1.2

，magnetic detuning ratio

b = 0.98

. Point A，B，C are backward wave oscillation points. The red circular area is convective instability area）

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Fig. 3. The coupling coefficient of 220 GHz PDL Gyro-TWT versus normalized guide center radius

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Fig. 4. The start current of absolute instability oscillation

U_{0} = 70 k V

, (a) losses circuit with different

b

, (b) lossy circuit with different conductance

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Fig. 5. The start length of backward wave oscillations with voltage

U_{0} = 70 k V

and current

I = 3 A

, (a) longitudinal field profiles in losses circuit, (b) start length changing versus different conductance

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Fig. 6. The linear gain versus frequency with losses and different conductance lossy circuit（

U_{0} = 70 k V

，

I = 3 A

，

α = 1.2

，

b = 0.98

）

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Fig. 7. The normalized field profiles of three backward wave oscillations in losses circuit（

U_{0} = 70 k V

，

I = 3 A

，

α = 1.2

，

b = 0.98

）

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Fig. 8. At 220 GHz，

U_{0} = 70 k V

I_{0} = 3 A

B = 8.16 T

a l p h a = 1.2

P_{i n} = 0.3 W,

σ = 58 S / m

(a) the effect of the number of periods on the output power and gain, when

L_{d} / L_{p} = 0.83

, (b) the effect of the dielectric slot ratio on the output power and gain when the number of periods is 21

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Fig. 9. At 220 GHz，comparison of gain versus interaction circuit length（

U_{0} = 70 k V

，

I_{0} = 3 A

，

B = 8.16 T

，

a l p h a = 1.2

，

P_{i n} = 0.55 W,

and

σ = 58 S / m

）

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Fig. 10.

P_{b e a m}

，

P_{o u t}

and

P_{l o s s}

versus interaction circuit length（

U_{0} = 70 k V

，

I_{0} = 3 A

，

B = 8.16 T

，

a l p h a = 1.2

，

P_{i n} = 0.3 W

and

σ = 58 S / m

，at 220 GHz）

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Fig. 11. The

T E_{11}

backward wave oscillation phenomenon (with

T E_{01}

as input signal at 220 GHz,

U_{0} = 70 k V

I_{0} = 3 A

P_{i n} = 0.55 W

L_{0} = 4.5 m m

L_{1} = 36 m m

L_{2} = 9.5 m m

ε_{r} = 11 - 4.4 J,

r_{o} - r_{w} = 0.3 m m

) (a) evolution of the quadratic root value of

P_{p e a k}

in the output part versus time (b) frequency spectrum of the output signals

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Fig. 12. Attenuation of dielectric versus the dielectric thickness with

ε_{r} = 11 - 4.4 J

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Fig. 13. The

T E_{21}

backward wave oscillation phenomenon (with

T E_{01}

as input signal at 220 GHz,

U_{0} = 70 k V

I_{0} = 3 A

P_{i n} = 0.55 W

L_{0} = 4.5 m m

L_{1} = 36 m m

L_{2} = 10.2 m m

ε_{r} = 11 - 4.4 J

r_{o} - r_{w} = 0.43 m m

) (a) evolution of the quadratic root value of

P_{p e a k}

in the output part versus time, (b) frequency spectrum of the output signals

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Fig. 14. Output port signal of the four mainly competitional modes versus the simulation time at zero drive

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Fig. 15. The 3D-PIC simulation results of optimized model (

P_{i n} = 0.55 W

, at 220 GHz) (a) evolution of the quadratic root value of

P_{p e a k}

in the output port versus time, (b) frequency spectrum of the output signals

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Fig. 16. Comparison of output power versus frequency with

P_{i n} = 0.55 W

at 220 GHz

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Fig. 17. Comparison of output power gain versus

P_{i n}

at 220 GHz

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Parameters	Specifications
Beam voltage $U_{0}$	70 kV
Beam current $I_{0}$	3 A
Velocity pitch factor $α$	1.2
Waveguide radius $r_{w}$	0.85 mm
Dielectric thickness（ $r_{o} - r_{w}$ ）	0.43 mm
Guiding center radius $r_{g}$	0.46* $r_{w}$
Operating mode	$T E_{01}$
Dielectric property（Beo-Sic）	11∼4.4 J
Operating magnetic field $B_{0}$	8.16 T
Structure length $L_{0}$ ， $L_{1}$ ， $L_{2}$	4.5 mm，50.4 mm，9.5 mm
Dielectric slot ratio $L_{d} / L_{p}$	0.83
Period length $L_{p}$	2.4 mm

Table 1. Design parameters of 220 GHz Gyro-TWT

Ru-Tai CHEN, Sheng YU. Theoretical study and PIC simulation of a 220 GHz Gyro-TWT with periodic dielectric loaded waveguide[J]. Journal of Infrared and Millimeter Waves, 2022, 41(6): 1042

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