The selection of operating mode for 10MW L-band MBK with high efficiency Institute of Electronics, Chinese Academy of Sciences Beijing, 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 TypeTH2108E3736VKL8301 ManufactureTEDToshibaCPI Operating ModeTM 010 (cylinder)TM 010 (coaxial)TM 020 +TM 010 Beam No.766 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/cm 2 ) 2.1

KEK and Toshiba E 3736 Thales TH 2108 CPI VKL － 8301

The choice of beam perveance Low beam perveance for getting high efficiency The relationship between efficiency and beam perveance η (%) = 90 − 20 × Per(μP) Per(μP) η (%)

The choice of beam perveance TypeManufac- ture Frequency (GHz) Power (MW) Voltage( kV) Current (A) Perveance (μP) Efficiency ( ％ ) TH2089Thales TH2105Thales E3718Toshiba VKP7952CPI 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: 6 Total beam perveance: 3.6μP Single beam perveance: 0. 6μP Beam voltage: 113kV (for efficiency of 65%) Beam current: 136.1A The beam parameters for 10MW L-band MBK Beam perveance: 2.0μP Beam voltage: 158kV (for efficiency of 50%) Beam current: 126.6A The beam parameters for 10MW L-band single beam klystron Beam perveance: 0.6μP Beam 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/cm 2 ， Temperature C, Lifetime: 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 TM 010 mode TM 020 mode TM 310 mode Coaxial cavity TM 010 mode TM 310 mode Rectangular cavity TM 210 mode TM 220 mode

Cylinder cavity TM 010 mode Diameter of cavity: 140mm Height of cavity: 50mm ， Location of drift tube: 90mm Gap distance: 15mm Size of drift tube ： Φ 16×Φ 24 Frequency:1316MHz R/Q=26.9(R=45), R/Q=30(R=35), R/Q=18(R=55), Radius of cathode ： 15~17.5mm Current density ： 3.2~2.36A/cm2 TM110 : F=1752MHz, MHz TM210: F=2148.6MHz, MHz

Cylinder cavity TM 310 mode Diameter of cavity:240mm Height of cavity: 70mm ， Location of drift tube: 168mm Gap distance: 15mm Size of drift tube ： Φ 20×Φ 28 Frequency:1346MHz R/Q=21.7(R=84), Radius of cathode ： 28~35mm Current density ： 0.92~0.59A/cm2

Coaxial cavity TM 010 mode Outer diameter of cavity: 150mm Inner Diameter of cavity: 40mm Height of cavity: 65mm ， Location of drift tube: 90mm Gap distance: 12mm Size of drift tube ： Φ 16×Φ 24 Frequency:1319MHz R/Q=26.2, Radius of cathode ： 28mm Radius of cathode ： 15~17.5mm Current density ： 3.2~2.36A/cm2 TM 110 : F=1424MHz, 1427MHz TM 210 : F=1623MHz, 1625MHz

Cylinder cavity TM 020 mode Diameter of cavity:240mm Height of cavity: 70mm ， Location of drift tube: 168mm Gap distance: 15mm Size of drift tube ： Φ 20×Φ 28 Frequency:1685MHz R/Q=6.61 (R=84), Radius of cathode ： 28~35mm Current density ： 0.92~0.59A/cm2

Coaxial cavity TM 010 mode Outer diameter of cavity:240mm Inner diameter of cavity: 90mm Height of cavity:60mm ， Location of drift tube: 168mm Gap distance: 15mm Size of drift tube ： Φ 20×Φ 28 Frequency:1316MHz R/Q=26 (R=84), Radius of cathode ： 28~35mm Current density ： 0.92~0.59A/cm2 TM110 ， F ＝ 1363MHz, 1366 MHz TM210 ， F ＝ 1463MHz, 1467MHz TM310 ， F ＝ 1520MHz,

Rectangular cavity TM 210 mode Size of cavity:220×57.5×50 Maximum distance among drift tubes: 162mm Gap distance: 15mm Size of drift tube ： Φ 20×Φ 28 Frequency:1295MHz R/Q=24.76, (X=-26,Y=0), R/Q=27.93, (X=-13,Y=22.5), Radius of cathode ： 15~17.5mm Current density ： 3.2~2.36A/cm2 TM110 ， F ＝ 1363MHz, 1366 MHz TM210 ， F ＝ 1463MHz, 1467MHz TM310 ， F ＝ 1520MHz,

Cavity TypeModeR/QCavity size Mode separation Cathode loading Beam location Field uniformity CylinderTM ×50440MHz3.2~2.36A/cm245Not good TM ×70 88MHz 0.92~0.59A/cm284good TM ×70 264MHz 0.92~0.59A/cm284good CoaxialTM ×65105MHz3.2~2.36A/cm245good TM ×6047MHz0.92~0.59A/cm284good RectangularTM ×6568MHz3.2~2.36A/cm281good The selection of operating mode

Freq.LSCX Peak Power(kW) Average Power(kW) Bandwidth(%) 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 KL4003 Peak power ： 1MW Average power ： 100kW Technology properties ： Hollow beam Anode modulation High power output window Supper evaporation collector

L-band high power klystron KL4028 Peak power 3.5MW KL4038 Peak power 1.0MW

S-band high power klystron KS MW KS MW, 50kW KS4064 5MW, 15kW

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