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 !!!