The NLC RF Pulse Compression and High Power RF Transport Systems Sami G. Tantawi, G.Bowden, K.Fant, Z.D.Farkas, W.R.Fowkes J.Irwin, N.M.Kroll, Z.H.Li,

The NLC RF Pulse Compression and High Power RF Transport Systems

Sami G. Tantawi, G.Bowden,

K.Fant, Z.D.Farkas, W.R.Fowkes

J.Irwin, N.M.Kroll,

Z.H.Li, R.Loewen, R.Miller,

C.Nantista, J.Rifkin, R.Ruth,

A.Vlieks, P.Wilson.

Outline

• System Requirements • Comparison between Different Pulse Compression

Systems• Single Moded Delay Line Distribution System (DLDS) • Multi-Moded DLDS• Summary• Collaborative work with KEK (Y. H. Chin)

– Development of multi-moded components

– Mode stability experiment

System Requirements and Goals

• Efficiency from klystrons to accelerator structures should exceed 85%.– Limited choice of systems– Component efficiency including copper losses should be better than 99%.

• Output Pulse should be flat for approximately 253 nS with a linear ramp at the beginning for approximately 104 nS. (Again this limits the choice of possible systems)

• The system should be cost effective– Reduced length of vacuum over-moded delay lines– Compact, and mechanically simple components.

• Peak surface field should be less than 40 MV/m at the rated rf power (600 MW for most components)

The development of various pulse compression systems has been an ongoing program at SLAC for over 10 years.

• Pulse compression systems that have the potential of achieving the NLC requirements and have been studied are:

– Resonant Delay Lines (SLED-II) • Active SLED-II• Multi-moded SLED-II

– Binary Pulse Compression (BPC)• Multi-Moded Reflective BPC

– Delay Line Distribution System (DLDS)• Multi-Moded DLDS• Active DLDS

• For each of these systems we calculated the following:– efficiency– number and cost of components– length and cost of delay lines– cost of klystrons– cost of modulators

Mode Launcher (A set Of 4 hybrids)

~7.4 cm Circular Waveguide

Single-moded DLDS

Klystron

~53 m

~12.7 cm Circular Waveguide Propagating The TE01 mode

Tantawi 8/97

Load

Single Moded DLDSThis system contains ~260 km of vacuum 4.75”-diameter waveguides

• Propagation of TE01 mode in circular over-moded waveguides, NLCTA experience

• Pump-outs

• Mode Converters

• Hybrids

• Flanges

• Tapers

• 90-Degree Bends

• Power Dividers for the Local Distribution System

• Experience gained from NLCTA – Propagation of the TE01 mode in highly over-moded waveguides (94

modes in the WC475, and 41 modes in WC293• Effect of Mechanical Tolerances on Circular Waveguides

– Diameter, Offset, Tilt, and Roundness

– Resonant Effects, and Mode Filters

• Design of Flanges

• Assembly Procedures

• Pump-outs

• Tapers

• Mode Converters (Flower Petal)

• Hybrids (Magic Tees)

• Measurement Techniques

The theoretical losses / 100 ns for a delay line with 4.75” diameter is 0.54%. This is

the delay line size used at the SLED-II pulse compressor at SLAC.

Test Lab

SLED II

NLCTA

Station #0

NLCTA

Station #1

NLCTA

Station#2

Compression Ratio 8 6 6 6

Pulse width (nS) 150 223 245 245

Delay LineLosses/100nS (%)

1.63 0.68 0.58 0.59

Intrinsic Q 4.3x105 1.05x106 1.37x106 1.21x106

Total Delay LineLosses (%)

5.05 3.63 2.34 2.39

External Losses (%) 4.85 6.89 6.36 5.26

Total Efficiency (%) 58.6 67.5 68.6 69.3

Comparison Between the 4 SLED II Systems at SLAC

0

50

100

150

200

0

1

Pow

er (

MW

)

Relative Pow

er (Cold Test)

2

3

4

-0.1 0.3 0.7 1.1 1.5Time (µs)

SLED IIXL-4

SLED IIInput Pulse

High Power

Cold Test

Most components have been designed with different concepts, for example:

• Mode Converters– based on the wrap-around concept– based on the Circular to Square Tapers

• Hybrids– Magic Tee– based on wrap around mode converters (Old concept)– based on circular to rectangular tapers (New Concept, presented here)

However, we present here only the most recent developments.

Old Marie’ Mode Converter

Short Marie’ Mode Converter (GA)

Flower Petal Mode Converter

Wrap-Around Mode Converter. Tested

up to 480 MW

Several Generations of Mode Converter

Development

HFSS simulation results for the wrap around mode converter. The color shades represents the magnitude of the electrical field. a. is a cut plane through the slots, b is a cut plane in the circular guide 2.5 cm away from the slots.

a

b

Input

Output

Wrap-around Mode Converter

H-Plane Over-moded Hybrid

Iris

Delay Lines

Sled-II Configuration

0

100

200

300

400

500

0 0.5 1 1.5 2

Pulse compressor inputPulse compressor output

Pow

er (

MW

)

Time (micro-seconds)

-5

-4

-3

-2

-1

0

11.3 11.35 11.4 11.45 11.5 11.55 11.6

Transmission throught the bend plus two TE10

rectangular to TE01

circular mode converters

dB

Frequency (GHz)

New 90-degree BendBased on Circular to Square Waveguide

Tapers

-40

-35

-30

-25

-20

-15

-10

-5

0

11.174 11.2573 11.3407 11.424 11.5073 11.5907 11.674

Circular TE01

mode Reflection Coefficient

dB

Frequency (GHz)

3.81 cm

3.556 cm

1.905 cm

Type 1: TE01 Circular to Square Taper

Coupling of the TE01 in the circular guide to spurious modes in the square guide. At the design

length for Type 2 taper.

-70

-60

-50

-40

-30

-20

-10

0

11.174 11.2573 11.3407 11.424 11.5073 11.5907 11.674

Transmission from circular TE0 1

to rectangular TE2 2

T ransmission from circular TE0 1

to rectangular TM2 2

dB

Frequency (GHz)

Field pattern of Type 2 taper when coupling from TE12 in the circular guide to TE03 in the square

guide

Type 2: TE01 and TE12 Circular to Square Taper.

10.16 cm

3.81 cm

A straight section. The cross section shape is given by

)2cos1.01()( 0 rr

2.54 cm

3.286 cm

2.54 cm

3.696 cm3.131 cm

Field Pattern as TE01in the circular guide get converted to TE20in the rectangular guide

-40

-35

-30

-25

-20

-15

-10

-5

0

11.174 11.2573 11.3407 11.424 11.5073 11.5907 11.674

Transmission to TE02

Transmission to TE20

Reflection to TE01

Reflection to TE21

dB

Frequency (GHz)

Type 3: TE01 Circular to TE20 Rectangular Taper.

Accelerator Structure Distribution System

8 Klystrons grouped in pairs

Single-moded DLDS


~7.4 cm Circular

Waveguide

Accelerator Structure (~1.8 m)

~ 6 m~53 m


TE12 Mode Extractor

TE01

TE12 (Vertical)TE12 (Horizontal)

TE01

TE12 (Vertical)

TE01

TE12 Mode Extractor

Mode Launcher (Fed by four rectangular waveguides)



8 Klystrons grouped in pairs

~ 6 m

TE01 Mode

TE01 Tap-off

Multi-moded DLDS

Multi-Moded Delay Line Distribution System This system contains ~130 km of vacuum 4.75”-diameter waveguides

• Introduction

• Experimental Tools

• Components required to implement the system (Launcher and Extractor)

• Components based on over-moded rectangular waveguides

• Components based on the wrap-around mode converter (will be presented by Y. H. Chin as part of component development at KEK)

• Flanges

• Tapers

• Mode Rotation Problems

0.5

0.6

0.7

0.8

0.9

1

1.1

1.2

4 6 8 10 12 14 16

Single Moded DLDSMulti-Moded DLDS (number of modes=3)Active DLDSMulti-Moded BPC (A high power circulator and 3 modes)Multi-Moded SLED II (A high power circulator and 3 modes) Active SLED II (One time Switching [7])Multi-Moded DLDS (n

k=4, number of modes =3)

Single-Moded DLDS (nk=4)

Rel

ativ

e C

ost

Compression Ratio

nk=8

TE21

TE01 Mode Extractor

TE01

TE12 (Vertically Polarized)

TE01

TE12 (Vertically Polarized)TE12 (Horizontally Polarized)



TE01

Mode Launcher (Fed by Four Rectangular Waveguides)

Klystrons

~ 6 m

TE12 to TE01 Mode Converter

~53 m


TE01 Tap-Off TE01 Mode Converter (Fed by Four Rectangular Waveguides)

TE21-TE01 Mode Converter

TE01 Mode Extractor(Power is Extracted Evenly Between Four Waveguides)



TE01


TE01


TE01

TE01 Mode Extractor


TE21


Klystrons

~ 6 mTE01 Mode Converter (Fed by Four Rectangular Waveguides)



TE01 Tap-Off

SLAC

KEK

Multi-Moded Structure test Setup

Mode Launcher (TE11 and TE01)Mode Pre-launcher, for testing launchers. The output phase of the four-waveguide output is controlled by the choice between the two inputs

TE11 (Vertical)TE12 (Horizontal)TE01

TE11 (Vertical)TE11 (Horizontal)

TE11 (Vertical)TE01

TE01

TE01 Extractor

To Accelerator Structures

TE01 Launcher

Extractor Schematic Diagram

TE12-TE11 Mode Converter TE12-TE11 Mode ConverterTE11-TE01 Mode Converter

TE01 Mode Extractor5”

Modular Launcher

TE11 Launcher TE01 LauncherTE01 Launcher

Both Polarizations of T

E 11

TE 01

TE 01

”

0.75

0.8

0.85

0.9

0.95

1

1.05

1.1

3 4 5 6 7 8 9

Single-Moded DLDSMulti-Moded DLDS

Rel

ativ

e C

ost o

f th

e rf

Sys

tem

Compression Ratio

Compression Ratio=WidthPulserAccelerato

WidthPulseKlystron

Cost Model

)1(max rm Ct

rC

T

2max r

gm

Cvtl

crkk

aac CnP

PNN

2

1max gm

k

aa

ck

vt

P

PN

nL

k

aa

crk P

PN

CN

1

rkk

aakmk SA

P

PNSSSS 0

000

0

1111 m

r

sm

r

sm

k

aa

cr

rsmmkm A

C

k

C

k

P

PN

C

CkANS

cc

r

pl

vll

rg

ckk

aaccc

pl

vlc nA

CDAAR

Cv

Pn

PNnANLDAAS

1

2

)1(

ka

r

rkk C

CAA

00

r

cpl

vll

r

k

c

r

sm

r

sm

m

a

r

r

rc

smc

vl

plmlkrr

C

nDkkR

C

n

k

C

k

C

kk

C

C

C

kkkkkRnDCS

k

2

)1(111

),,,,;,,,(

00

c

gvlv

lk

cc

k

mm A

vAk

A

Ak

A

Ak

,,

00

c

gp

lpl A

vAk

Single Moded DLDS

3

771.46901DTE dB/S;

itc 9.0

rk Cn

5.0lR

1i

3

3

456.8

456.8

101

101

Dr

CD

t

C

r

T h e s y s t e m r e q u i r e s t h e f o l l o w i n g c o m p o n e n t s :

i . )( rk Cn h y b r i d s ( e a c h h y b r i d i s c o u n t e d a s o n e c o m p o n e n t )

i i . )( rk Cn l o a d s ( e a c h l o a d i s c o u n t e d a s o n e c o m p o n e n t )

i i i . rC2 T E 0 1 b e n d ( e a c h b e n d i s c o u n t e d a s o n e c o m p o n e n t )

i v . )1(log2 2 r

r CC

h i g h p o w e r h y b r i d s , e a c h h y b r i d i s c o u n t e d a s t w o c o m p o n e n t s .

v . 2

rC s u p e r - h i g h p o w e r h y b r i d s , e a c h i s c o u n t e d a s f o u r c o m p o n e n t s

H e n c e , t h e t o t a l n u m b e r o f c o m p o n e n t s i s g i v e n b y :

)1(log2 2 rrkc CCnn .

Single Moded DLDS3

771.46901DTE dB/S;

itc 9.0

rk Cn

5.0lR

1i

3

3

456.8

456.8

101

101

Dr

CD

t

C

r


i . )( rk Cn h y b r i d s

i i . )( rk Cn l o a d s

i i i . rC2 T E 0 1 b e n d

i v . )1(log2 2 r

r CC

h i g h p o w e r h y b r i d s

v . 2

rC s u p e r - h i g h p o w e r h y b r i d s

v i . 4

3 rC t a p - o f f s

systemunitKlystronsofNumbern

RationCompressioC

k

r

/




i i i . rC2 T E 0 1 b e n d

i v . )1(log2 2 r

r CC

h i g h p o w e r h y b r i d s

v . 2

rC s u p e r - h i g h p o w e r h y b r i d s

v i . 4

3 rC t a p - o f f s


RationCompressioC

k

r

/

Single-Moded DLDS

Multi-Moded DLDS ;5.01

m

rp n

Cn

)1(

)1(2/1(

rr

pmrpl CC

nnCnR

m

pmrj

mj

pmjn

j

nnjC

n

nn

rt C 1

120

20

20

10

101

1011

1

T h e s y s t e m r e q u i r e t h e f o l l o w i n g c o m p o n e n t s :



i i i . )( pr nC T E 0 1 b e n d

i v . pn m o d e l a u n c h e r .

v . )( pr nC m o d e e x t r a c t o r s .


RationCompressioC

k

r

/

DDTE

67185.1336.909312 dB/S

3

771.46901DTE dB/S;

rl C

R1

r

rCoff

sonsoff

s

Coffs

r

tC

1

111

3

456.8

10 D


i . )( rk Cn h y b r i d s ( e a c h h y b r i d i s c o u n t e d a s o n e c o m p o n e n t )

i i . )( rk Cn l o a d s ( e a c h l o a d i s c o u n t e d a s o n e c o m p o n e n t )

i i i . rC T E 0 1 b e n d ( e a c h b e n d i s c o u n t e d a s o n e c o m p o n e n t )

i v . O n e T E 0 1 m o d e l a u n c h e r , ( c o u n t e d a s t w o c o m p o n e n t s ) .

v . )1( rC s w i t c h e s ( e a c h c o u n t e d a s s i x c o m p o n e n t s ) .

T h e t o t a l n u m b e r o f c o m p o n e n t s i s g i v e n b y

452 rkc Cnn .

Active DLDS

Single-Moded BPC

hC

CR rh

rl 1log

2

11

1

22

rk

r

rkk

Cn

PC

Cn

P

n

P

h

75

2log

75

2

75

2log

max2

maxmax2

3

3

9.16

9.16

101

101

Dr

CD

t

C

r


i . )2( kn h y b r i d s ( e a c h h y b r i d i s c o u n t e d a s o n e c o m p o n e n t )

i i . )2( kn l o a d s ( e a c h l o a d i s c o u n t e d a s o n e c o m p o n e n t )

i i i . 2 rC T E 0 1 b e n d ( e a c h b e n d i s c o u n t e d a s o n e c o m p o n e n t )

i v .

1

22

hrC

h h i g h p o w e r h y b r i d s , ( c o u n t e d a s f o u r c o m p o n e n t s ) .

v .

1

22

hrC

s p l i t t e r s ( e a c h c o u n t e d a s t h r e e c o m p o n e n t s ) .

T h e t o t a l n u m b e r o f c o m p o n e n t s i s g i v e n b y :

1842

1422

hCnn

hrkc .

Multi-Moded BPC

hC

CnR rh

rml 1log

2

11

1

22

mn

i m

i

r

mn

i m

i

n

r

Cn

t

C 1

1

10

10

101

101


i . )2( kn h y b r i d s ( e a c h h y b r i d i s c o u n t e d a s o n e c o m p o n e n t )

i i . )2( kn l o a d s ( e a c h l o a d i s c o u n t e d a s o n e c o m p o n e n t )

i i i . 2 rC T E 0 1 b e n d ( e a c h b e n d i s c o u n t e d a s o n e c o m p o n e n t )

i v .

1

22

hrC

h h i g h p o w e r h y b r i d s , ( c o u n t e d a s f o u r c o m p o n e n t s ) .

v .

1

22

hrC

s p l i t t e r s ( e a c h c o u n t e d a s t h r e e c o m p o n e n t s ) .

v i . mhr n

Ch

1

22 m o d e c o n v e r t e r s , ( e a c h i s c o u n t e d a s o n e c o m p o n e n t )

T h e t o t a l n u m b e r o f c o m p o n e n t s i s g i v e n b y

mmhm

rkc nhnn

Cnn 21842

21422



TE01


TE01


TE01

TE01 Mode Extractor


TE21


Klystrons

~ 6 mTE01 Mode Converter (Fed by Four Rectangular Waveguides)



TE01 Tap-Off

SLAC

KEK

Eight 75-megawatt klystrons

RF

e+ or e- A Cluster of 9 Multi-Moded DLDS Sections

RF Power Sources

A Single Multi-Moded Delay Line RF Distribution System

Accelerator Structures

Delay Lines

Relative Cost

Efficiency

Relative Cost

Efficiency

Waveguide Diameter (cm)

Waveguide Diameter (cm)

Single-moded System

Multi-Moded System

C o m p n en t D e ve lo p m e nt

S in g le -M o d e d D L D S M u lti-M o de d D L DS E xp erim e n ta l S e tu ps(S L E D -II)

A p p lica tion

O ve r-m o d ed C ircu la r W a ve gu id esC o m p o ne n ts B a se d o n the W ra p-A rou n d M o de C o n ve rte r

T a p e rs

O ve r-M od e d R e cta n gu la r W ave g u id e C o m p o ne n tsC o m p o ne n ts b a se d o n H -p lan e d iscon tinu ties

A d ia b a tic T ap e rs Fro m R e c ta ng u la r T o C ircu la r G u id esT E 2 0 -----> T E 0 1T E 3 0 -----> T E 1 2

O ve r-M o de d R e c tan g u la r W a ve gu id esM ixe d w ith O ve r-M o d e d C ircu la r w a veg u id es

T yp e



Single-moded DLDS

Klystron

~53 m

~12.7 cm Circular Waveguide Propagating The TE01 mode

Tantawi 8/97

Load

Wrap-Around Mode Converter for Tap-off, and extraction, tested to 320MW

Instead of using a cutoff section to allow the extraction of the TE01 mode, one can use two mode converters cascaded together

A short circuit

Y0=1 Y0=1

Y0=1 Y0=1

Y0=1

Y0=1

Y0=1Y0=1

5

1

5

2

5

4

5

25

2

5

1

5

2

5

45

4

5

2

5

1

5

25

2

5

4

5

2

5

1

jj

jj

jj

jj

S

4/

4/

Port 1

Port 2

Port 3

Port 4

If a signal is injected in port 1, it will all appear in port 3.


TE01 Mode Extractor

Compact Mode Extractor

Compact Launcher

Mode Pre-launcher, for testing launchers. The output phase of the four-waveguide output is controlled by the choice between the two inputs

1.5”~7”

A bend based on transition from an over-moded rectangular waveguide to a circular waveguide

TIMING

Because the rf power is being injected at different times into different modes that have different group velocities, one must pay a special attention to timing. The set of equation that need to be satisfied so that the each accelerator structure set get an rf pulse for a duration at the appropriate time are:

(1)

where L is the distance between accelerator structure sets, L1 is the distance between the launcher and first extractor, L2 is the distance between first and second extractor, L3 is the length of the delay line after the second extractor, vTE01 and vTE12 are the group velocities of the TE01 and TE12 modes respectively, and through are the delays due to the transmission of power from the main rf delay line system to the accelerator structure sets, i.e., the delay through and after the extractors.There are several choices for the lengths L, L1 through L3, and through that satisfy the above set of equations. An attractive choice is to set L1 through L3 equal to L, == and

(2)

This would lead to a fairly symmetric system.

);11

()()(

),11

()()(

),()(

0112234

01

3

0112123

01

2

1201

1

TETETE

TETETE

TE

vvL

c

L

v

L

vvL

c

L

v

L

c

L

v

L

)11

(0112

12TETE vv

L

LAUNCHER

Several ideas for the launcher have been proposed (8-9). In all of them a fundamental property of the launcher has been preserved: the launcher has only four inputs and the launcher has to launch four and only four modes. If this is preserved and the launcher is matched for all four different input conditions, because of unitarity and reciprocity the scattering matrix representing the launcher has to take the following form:

(3)

This form forces the isolation between inputs; i.e., if one of the four power supplies drops out or fails, the rest of the power supplies will not receive any reflected power.

00002/12/12/12/100002/12/12/12/100002/12/12/12/100002/12/12/12/12/12/12/12/100002/12/12/12/10000

2/12/12/12/100002/12/12/12/10000

S

Advanced Concepts

• Distributed Elements

• Circulators

• Switches

Summary• We have a design for all components required to

implement the Single Moded DLDS, and the Multi-Moded DLDS.

• Going from single-moded to multi-moded systems will be decided after the KEK-SLAC experiment which will study the propagation properties of the TE12 mode (Details of the experiment described by Y. H. Chin).

• High power experimental setups are being prepared to demonstrate these systems.

Documents

The NLC RF Pulse Compression and High Power RF Transport Systems Sami G. Tantawi, G.Bowden, K.Fant, Z.D.Farkas, W.R.Fowkes J.Irwin, N.M.Kroll, Z.H.Li,