The selection of operating mode for 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

Type TH2108 E3736 VKL8301

Manufacture TED Toshiba CPI

Operating Mode TM010(cylinder) TM010(coaxial) TM020+TM010

Beam No. 7 6 6

Beam Voltage (kV) 115 (117) 115(115) 114(120)

Beam Current(A) 133(131) 132(133) 131(141)

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

Cathode Loading (A/cm2)

2.1 2.1

KEK and Toshiba

E 3736Thales

TH 2108

CPI VKL － 8301

The choice of beam perveance

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

Per(μP) 2 1.5 1.0 0.75 0.50 0.25

η (%) 50 40 70 75 80 85

The choice of beam perveance

Type Manufac-ture

Frequency(GHz)

Power(MW)

Voltage(kV)

Current(A)

Perveance(μP)

Efficiency(％ )

TH2089 Thales 0.352 1.1 87.5 18.5 0.71 68

TH2105 Thales 0.508 1.0 90 18.5 0.685 60

E3718 Toshiba 1.25 1.2 85 22.4 0.903 63

VKP7952 CPI 0.7 1.0 95 21.0 0.717 65

Low frequency, high efficincy CW klystron

60 ～ 70 ％ of efficiency have been reached for klystron 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 lifetime

for 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 satellite TWTs Lifetime can reach 200,000 hrs.(given by NEC)

Coated （ Os ） Impregnated Cathode, loading 4A/cm2 ， Temperature 9850C, Lifetime: 150.000 hrs. (IOT) 。 (Thales)

The choice of focusing system

1. In order to obtain high peak power and high average power, high beam transmission for both DC and RF state is necessary.

2. Electromagnet focusing system is adopted for getting high beam transmission.

3. It is necessary to reduce the transverse field at the beam location for getting high beam transmission.

4. The distance from the axis to beam location have big influence on the weight and volume of tube and focusing system.

The selection of operating mode

Cylinder cavity TM010 mode TM020 mode TM310 mode

Coaxial cavity TM010 modeTM310 mode

Rectangular cavity TM210 mode

TM220 mode

Cylinder cavity TM010 mode Diameter of cavity: 140mmHeight of cavity: 50mm ， Location of drift tube: 90mm Gap distance: 15mm Size of drift tube ： Φ 16×Φ 24 Frequency: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 mode Diameter of cavity:240mmHeight of cavity: 70mm ， Location of drift tube: 168mm Gap distance: 15mm Size of drift tube ： Φ 20×Φ 28 Frequency:1346MHzR/Q=21.7(R=84), Radius of cathode ： 28~35mmCurrent density ： 0.92~0.59A/cm2

Coaxial cavity TM010 mode Outer diameter of cavity: 150mmInner Diameter of cavity: 40mmHeight of cavity: 65mm ， Location of drift tube: 90mm Gap distance: 12mmSize of drift tube ： Φ 16×Φ 24 Frequency: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 mode

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

Coaxial cavity TM010 mode

Outer diameter of cavity:240mmInner diameter of cavity: 90mmHeight of cavity:60mm ， Location of drift tube: 168mm Gap distance: 15mm Size of drift tube ： Φ 20×Φ 28 Frequency: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 mode

Size of cavity:220×57.5×50Maximum distance among drift tubes: 162mm Gap distance: 15mm Size of drift tube ： Φ 20×Φ 28 Frequency: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,

Cavity Type Mode R/Q Cavity size

Mode separation

Cathode loading

Beam location

Field uniformity

Cylinder TM010 26.9 140×50 440MHz 3.2~2.36A/cm2 45 Not good

TM310 21.7 240×70 88MHz 0.92~0.59A/cm2 84 good

TM020 6.6 240×70 264MHz 0.92~0.59A/cm2 84 good

Coaxial TM010 26.2 150×65 105MHz 3.2~2.36A/cm2 45 good

TM310 26 240×60 47MHz 0.92~0.59A/cm2 84 good

Rectangular TM210 25 220×65 68MHz 3.2~2.36A/cm2 81 good

The selection of operating mode

Freq. L S C X

Peak Power(kW) 75-200 120-200 30-600 50-75

Average Power(kW) 4-100 6-10 2-10 2.5-5

Bandwidth(%) 6-12 8-10 2-8 4-5

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-Beam Klystron with bandwidth of 12% is currently being 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 modes in CW state

L-band high power klystron

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

L-band high power klystron

KL4028Peak power 3.5MW

KL4038Peak power 1.0MW

S-band high power klystron

KS411950MW

KS41211.8MW, 50kW

KS40645MW, 15kW

Thanks ！！！