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04/19/23Pengda Gu , Structure Meeting

Study on 30GHz Pulse Compressor

1. Simulation of a multi-cavity RF pulse compressor using a coupled resonator model

2. Design of the multi-mode SLED-II type pulse compressor

3. Design of the components of 30GHz pulse stretcher for CTF2

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04/19/23Pengda Gu , Structure Meeting

1.1 The model

From this model , we can get the following equation

11201

20

102

12

111201

20

02

2

212011

20

021

2

)1(

12),()1(

1)1(

NNNNN

N

N

nnnnnnnn

n

n

inn

l

ikikdt

di

Qdt

id

Nnikikikkdt

di

Qdt

iddt

dV

Likik

dt

di

Qdt

id

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04/19/23Pengda Gu , Structure Meeting

1.2 Steady state or frequency domain solutions

For uniform coupled resonators where every cell is the same and cell number is very large

2/sin41 20 k

Fig 2 Dispersion curve

The numerical solution of the eignmodes of a 16-cell coupled resonators.

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1.3 Time domain solutions and optimization

1.3.1 Quasi steady-state tjetIti )()(

tjin VeV

1120

021

20

02

2

11120

021

20

02

2

21201

021

20

102

12

])1([)2(

12),(])1([)2(

])1([)2(

NNNN

NN

N

N

nnnnnn

nnn

n

n

ll

IkIQ

jk

dt

dI

Qj

dt

Id

NnIkIkIQ

jkk

dt

dI

Qj

dt

IdL

VjIkI

Q

jk

dt

dI

Qj

dt

Id

mnn ItI )(

t

II

dt

dI mn

mnn

2

11

)2(1 11

22

2mn

mn

mn III

tdt

Id

1.3.2 Simulation results of 7 cavities a. The Q factor of all cavities is

5102

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Fig 3 Output waveform before optimization Fig 4 Output waveform afteroptimization

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04/19/23Pengda Gu , Structure Meeting

b. With low Q factor cavities

Fig 5 7 cavities with 3 low Q cavities

cavity arrangement

HLHLHLH HLLHLLH HLLLLLH LHLHLHL LLHLHLL

efficiency 60.8% 48.3% 48.3% 43.8%(beta=8) 44.4%(beta=8)

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04/19/23Pengda Gu , Structure Meeting

1.3.3 Other simulations

Fig 8 5 cavities with 2 low Q cavities Fig 9 9 cavities with 4 low Q cavities

Fig 6 Output waveform of 8 cavities Fig 7 8 cavities with 4 low Q cavities

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04/19/23Pengda Gu , Structure Meeting

1.4 Conclusiona .RF pulse compressors with multi cavities can provide better output waveform than SLED. b. The efficiency is still not so good, around 60%. c. There is phase variation in the output pulse.d. The frequency tolerance as simulated in the 7-cavity case is too tight, which is about 0.001%.

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2. Design of the 30GHz multi-mode SLED-II type pulse compressor (Based on the NLC multi-mode SLED-II approach)

Input

Output

Rectangle TE10 to Circular TE01 Mode converter

Iris

Mode Preserving taperCutoff for TE02mode

Dual mode pipe

Reflective TE01 TE02Mode converterAnd tuning plunger

TE01TE02TE02TE01

Fig 1 Schematic drawing

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3. Design of the components of 30GHz pulse stretcher for CTF2

3.1 Rectangle TE10 to circular TE01 mode converter

Composition:

Taper from 8.64mm wide to 12.35mm wide + Rectangle TE10 to TE20 mode converter +Taper from 4.32mm high to 12.5mm high +Rectangle TE20 to circular TE01 mode converter

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04/19/23Pengda Gu , Structure Meeting

Fig 2 Electric field

5mm

Fig 3 dimension

Taper from 8.64mm wide to 12.35mm wide

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Fig 4 Matrix plot

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04/19/23Pengda Gu , Structure Meeting

Rectangle TE10 to TE20 converter

Fig5 Electric field 450

450

50.20

330

17m

m

17m

m

17.4

mm

17.4

mm

x

y

(20,17)

(44.04,-7.04)

(13.46,28.48)

12.3

5mm 14

.09m

m

Fig 6 Dimensions of the converter

S Matrix at 29.9855GHz

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Fig 7 S12 conversion from TE10 to TE20 and the reflection S11

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Taper from 4.32mm high to 12.5mm high No.1

Fig 8 Electric field

21mm

Fig 9 Dimension

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Fig 10 Matrix plot of S12 , S11of TE20 mode

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Fig 11 Electric field

5.9m

m

8.8m

m

11.1mm

21.8mm

Taper from 4.32mm high to 12.5mm high No.2

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04/19/23Pengda Gu , Structure Meeting

Fig 12 S11 and S12 of TE20 mode

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Taper from 4.32mm high to 12.5mm high No.3

Fig 13 Electric field

26mm

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Fig 14 S11 and S12 of TE20 mode

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Rectangle TE20 to circular TE01 mode converter

Fig 15 Electric field

S Matrix at 29.9855GHz

14.5mm

6.27mm

11.03mm

7.3mm

12.5mm14.094mm

Profile :)2cos12.01(25.7 r

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Fig 16 Matrix plot of rectangle TE20 to circular TE01 conversion, S11 of port 1:m1 (dashed), S11 of port1:m1 to port1:m2,S12 of port1:m1 to port2:m1(dotted)

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Simulation of the total structure

Fig 17 Electric field , using taper from 4.32mm high to 12.5mm high No.1

132.6mm

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Fig 18 Matrix plot of S12, conversion from rectangle TE10 mode to circular TE01mode and S11

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3.3 Circular mode preserving taper

Fig 19 TE01 mode transmission

Fig 20 Reflection of TE02 mode

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Fig 21 S12 for H01 mode as a function of taper length

Fig 22 S11 for H01 mode

Fig 23 Reflection of H02 mode as a function of taper length

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3.4 Reflective circular TE01 to TE02 converter

Fig 24 Field plot of the magnitude of E, excited by mode

oTE01

Fig 25 Field plot of complex magnitude of E, excited by mode oTE

01

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Fig 26 Matrix plot of reflection and TE01 TE02 conversion