The selection of operating modefor 10MW L-band MBK with high efficiency

Institute of Electronics, Chinese Academy of SciencesBeijing, China

November 7, 2007

Yaogen Ding, Yong Wang, Zhaozhuan Zhang

Introduction

The requirement of ILC

10MW L-band MBK

Peak power: 10MW

Average power: 150kW

High efficiency for saving energy

Long lifetime

Introduction

Recent progress of 10MW L-band MBK

2.12.1Cathode Loading(A/cm2)

65(59)65(66)65(68)Efficiency(%)

131(141)132(133)133(131)Beam Current(A)114(120)115(115)115 (117)Beam Voltage (kV)667Beam No.TM020+TM010TM010(coaxial)TM010(cylinder)Operating ModeCPIToshibaTEDManufactureVKL8301E3736TH2108Type

KEK and ToshibaE 3736Thales

TH 2108

CPIVKL－8301

The choice of beam perveance

Low beam perveance for getting high efficiencyThe relationship between efficiency and beam perveanceη (%) = 90 − 20 × Per(µP)

858075704050η (%)

0.250.500.751.01.52Per(μP)

The choice of beam perveance

650.71721.0951.00.7CPIVKP7952

630.90322.4851.21.25ToshibaE3718

600.68518.5901.00.508ThalesTH2105

680.7118.587.51.10.352ThalesTH2089

Efficiency(％)

Perveance(µP)

Current(A)

Voltage(kV)

Power(MW)

Frequency(GHz)

Manufac-ture

Type

Low frequency, high efficincy CW klystron

60～70％ of efficiency have been reached forklystron with beam perveance 0.6~0.9μP 。

The choice of beam parameters

Beam Number: 6Total beam perveance: 3.6µPSingle beam perveance: 0. 6µPBeam voltage: 113kV (for efficiency of 65%)Beam current: 136.1A

The beam parameters for 10MW L-band MBK

Beam perveance: 2.0µPBeam voltage: 158kV (for efficiency of 50%)Beam current: 126.6A

The beam parameters for 10MW L-band single beam klystron

Beam perveance: 0.6µPBeam voltage: 231kV (for efficiency of 65%)Beam current: 66.6A

The choice of cathode loading

The relationship between cathode loading and lifetimefor M-type cathode

Emission current density Lifetime 2.0A/cm2, 145,000 hrs 4.0A/cm2, 85,000 hrs 8.0A/cm2, 27,000 hrs

Klystron (given by CPI)

Life test evaluation of 411M cathode for highly reliable satelliteTWTsLifetime can reach 200,000 hrs.(given by NEC)

Coated （Os）Impregnated Cathode, loading 4A/cm2，Temperature9850C, Lifetime: 150.000 hrs. (IOT)。(Thales)

The choice offocusing system

1. In order to obtain high peak power and highaverage power, high beam transmission forboth DC and RF state is necessary.

2. Electromagnet focusing system is adoptedfor getting high beam transmission.

3. It is necessary to reduce the transverse fieldat the beam location for getting high beamtransmission.

4. The distance from the axis to beam locationhave big influence on the weight and volumeof tube and focusing system.

The selection of operating mode

Cylinder cavity TM010 mode TM020 mode TM310 mode

Coaxial cavity TM010 modeTM310 mode

Rectangular cavityTM210 modeTM220 mode

Cylinder cavity TM010 modeDiameter of cavity: 140mmHeight of cavity: 50mm，Location of drift tube: 90mmGap distance: 15mm Size of drift tube：Φ 16×Φ 24Frequency:1316MHzR/Q=26.9(R=45), R/Q=30(R=35),R/Q=18(R=55),Radius of cathode：15~17.5mmCurrent density：3.2~2.36A/cm2TM110 : F=1752MHz, 1754.8MHzTM210: F=2148.6MHz, 2150.8MHz

Cylinder cavity TM310 modeDiameter of cavity:240mmHeight of cavity: 70mm，Location of drift tube: 168mmGap distance: 15mm Size of drift tube：Φ 20×Φ 28Frequency:1346MHzR/Q=21.7(R=84),Radius of cathode：28~35mmCurrent density：0.92~0.59A/cm2

Coaxial cavity TM010 modeOuter diameter of cavity: 150mmInner Diameter of cavity: 40mmHeight of cavity: 65mm，Location of drift tube: 90mmGap distance: 12mmSize of drift tube：Φ 16×Φ 24Frequency:1319MHzR/Q=26.2,Radius of cathode：28mmRadius of cathode：15~17.5mmCurrent density：3.2~2.36A/cm2TM110 : F=1424MHz, 1427MHzTM210: F=1623MHz, 1625MHz

Cylinder cavity TM020 modeDiameter of cavity:240mmHeight of cavity: 70mm，Location of drift tube: 168mmGap distance: 15mm Size of drift tube：Φ 20×Φ 28Frequency:1685MHzR/Q=6.61 (R=84),Radius of cathode：28~35mmCurrent density：0.92~0.59A/cm2

Coaxial cavity TM010 modeOuter diameter of cavity:240mmInner diameter of cavity: 90mmHeight of cavity:60mm，Location of drift tube: 168mmGap distance: 15mm Size of drift tube：Φ 20×Φ 28Frequency:1316MHzR/Q=26 (R=84),Radius of cathode：28~35mmCurrent density：0.92~0.59A/cm2TM110， F＝1363MHz, 1366 MHzTM210， F＝1463MHz, 1467MHzTM310， F＝1520MHz,

Rectangular cavity TM210 modeSize of cavity:220×57.5×50Maximum distance among drift tubes:162mmGap distance: 15mm Size of drift tube：Φ 20×Φ 28Frequency:1295MHzR/Q=24.76, (X=-26,Y=0),R/Q=27.93, (X=-13,Y=22.5),Radius of cathode：15~17.5mmCurrent density：3.2~2.36A/cm2TM110， F＝1363MHz, 1366 MHzTM210， F＝1463MHz, 1467MHzTM310， F＝1520MHz,

good813.2~2.36A/cm268MHz220×6525TM210Rectangular

good840.92~0.59A/cm247MHz240×6026TM310

good453.2~2.36A/cm2105MHz150×6526.2TM010Coaxial

good840.92~0.59A/cm2264MHz240×706.6TM020

good840.92~0.59A/cm288MHz240×7021.7TM310

Not good453.2~2.36A/cm2440MHz140×5026.9TM010Cylinder

Fielduniformity

Beamlocation

Cathodeloading

Modeseparation

Cavitysize

R/QModeCavity Type

The selection of operating mode

4-52-88-106-12Bandwidth(%)

2.5-52-106-104-100Average Power(kW)

50-7530-600120-20075-200Peak Power(kW)

XCSLFreq.

Multi-Beam Klystrons of IECAS

C band MBK(IECAS)

S band MBK(IECAS)L band MBK(IECAS)

100kW L-band CW MBK (IECAS )

A L-band 100 kW CW Broadband Multi-BeamKlystron with bandwidth of 12% is currentlybeing developed at IECAS. The main design 18 beams 6 buncher cavities Filter-loaded double-gap coupling cavity Coil focusing

The main technical difficulties High CW output power Wide bandwidth(12%) Instability and oscillation of parasitic modesin CW state

L-band high power klystronL-band high power klystron KL4003Peak power：1MWAverage power：100kWTechnology properties：Hollow beamAnode modulationHigh power output windowSupper evaporation collector

L-band high power klystron

KL4028Peak power3.5MW

KL4038Peak power1.0MW

S-band high power klystron

KS411950MW

KS41211.8MW, 50kW

KS40645MW, 15kW

Thanks！！！