RF Technology Professor Richard Carter Lancaster University Engineering Department 23 rd November 2006.

RF Technology

Professor Richard CarterLancaster University Engineering Department

23rd November 2006

RF Presentation to CI SAC 23 Nov 2006 2

Research group focus

• Electromagnetics• High power RF and

microwave engineering• Particle dynamics in RF

electromagnetic fields• Vacuum electronics

Courtesy of Thales Electron Devices

RF Presentation to CI SAC 23 Nov 2006 4

Staff

• Academic staff– Prof. Richard Carter– Dr Amos Dexter– Dr Rebecca Seviour

• Research staff– Dr Graeme Burt– Dr Richard Jenkins– Jonny Smith– Imran Tahir– 2 Vacancies

• Research Students– Chris Hill– Sharon Crane– Fay Hannon– Emma Wooldridge– Chris Lingwood

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Resources• Microwave laboratory

– Test equipment– High power sources– Vacuum equipment– Auger spectrometer

• Software– Commercial

• (MAFIA, MWS, Lorenz HF, MAGIC, KOBRA3, Accelrys, GdfidL, FEMLab)

– Indigenous • (Small and large-signal models for klystrons and travelling-wave

tubes, models of helix and coupled-cavity slow-wave structures)

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Current research projects

• Microwave tubes– Stabilisation of c.w. magnetron oscillators– High power magnetron for IFMIF – Radial inductive output tubes– Multiple beam klystron for CLIC

• Particle accelerators– Energy recovery linac stability for 4GLS– Crab cavity system for the ILC– Collimator for the ILC– High brightness gun for 4GLS

• RF vacuum breakdown (Multipactor)

RF Presentation to CI SAC 23 Nov 2006 7

Future research projects

• Superconducting RF systems

• Parallel operation of stabilised magnetrons

• Secondary electron emission theory

• Cavity technology for the Neutrino Factory

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Stabilisation of c.w. magnetron oscillators

• Dr Amos Dexter, Imran Tahir

• PLL control of frequency• Injection locking• Phase locking to better

than 1%• Injected power – 37dB• Magnetrons could be used

as high efficiency, low cost sources for accelerators

-80

-60

-40

-20

0

2.430 2.440 2.450 2.460 2.470

Frequency (GHz)

-80

-60

-40

-20

0

2.43 2.44 2.45 2.46 2.47

Frequency (GHz)

-80

-60

-40

-20

0

2.4496 2.4498 2.45 2.4502 2.4504

Frequency(GHz)

RBW 2KHz

• Free-running magnetron

• Magnetron with PLL frequency control

• Magnetron with PLL control and injection

RF Presentation to CI SAC 23 Nov 2006 9

High Power RF Sources for IFMIF• Prof Richard Carter, Carl Beard• Conceptual design report:1 MW c.w., 175 MHz, 90% efficiency

Diacrode IOT Magnetron

Anode voltage

14 kV 95 kV 60 kV

Anode current

103 A 58 A 20 A

Efficiency 71% 65% (>75% with a multi-element depressed collector

90 %

Gain 13 dB 23 dB > 30 dB

Drive power 50 kW 5 kW < 1 kW

Cooling Anode Collector Anode and (probably) cathode

Electro-magnet

No Yes (except the radial IOT) Yes

Availability Yes Would require 2 - 3 years R&D Would require 4 – 5 years R&D

R&D issues None • Mechanical stability of control grid• Multi-element depressed collector design• Multi-beam and radial beam designs

• Cathode choice for long life• Development of switched mode power supply • Demonstration of simultaneous control of amplitude and phase• Stability

RF Presentation to CI SAC 23 Nov 2006 10

Radial inductive output tubes

• Sharon Crane (PhD student),

• Prof. Richard Carter

• Collaboration with E2V Technologies

• Target 1 GHz, 1 MW c.w.

Collector

Output cavity

Input cavityRF Output

Grid bias and RF Input

Cathode

Anode

RF Presentation to CI SAC 23 Nov 2006 11

Multiple beam klystron for CLIC

• Chris Lingwood (PhD student), Prof. Richard Carter

• Investigation of novel multiple beam klystron concepts for CLIC

• 1 GHz, 50 MW pk

• Collaboration with CERN and Thales Electron Devices

• Previous project – Future Linear Collider Klystron Study – Dr Jinjun Feng, Collaboration with CERN, DESY, E2V

Technologies, TMD Technologies.

RF Presentation to CI SAC 23 Nov 2006 12

Energy recovery linac stability for 4GLS

• Emma Wooldridge (ASTeC Staff, PhD Student)

• Prof. Richard Carter

• Susan Smith (ASTeC)

• Study of beam break-up and its prevention

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High brightness gun for 4GLS

• Fay Hannon (PhD student) • Dr Rebecca Seviour• Dr Bob Rimmer (JLab)• Project funded and based at JLab

RF Presentation to CI SAC 23 Nov 2006 15

RF vacuum breakdown (Multipactor)

• Dr Rebecca Seviour, Dr Richard Jenkins, Dr Matt Stables, Chris Hill (PhD Student), Prof. Richard Carter

• Theoretical and experimental study of multipactor discharges in complex structures

• Collaboration with E2V Technologies

• Previous project – Multipactor in the CESR RF system, – Dr Philippe Goudket, Professor Richard Carter, Mike Dykes

(ASTeC) – Collaboration with Cornell University

RF Presentation to CI SAC 23 Nov 2006 16

Multipactor – Experimental Work

• Chris Hill (PhD Student) • Prof Richard Carter• Multipactor in a klystron input cavity

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Multipactor – Simulation

• Dr Rebecca Seviour• Dr Matt Stables

• Aim – Computer simulation of multipactor in complex geometries

• Issues– Accuracy of fields close to

surfaces– Knowledge of energy spectrum

of secondary electrons

RF Presentation to CI SAC 23 Nov 2006 18

Multipactor – Secondary Electron Emission Measurements

• Dr Richard Jenkins• Prof Richard Carter• Re-commissioning of Auger

spectrometer

E.D.C. for different beam voltages

0

0.5

1

1.5

2

2.5

3

-410 -370 -330 -290 -250 -210 -170 -130 -90 -50 -10

Retarding Potential E

N(E

)

100V150V200V300V400V

Acid cleaned, not outgased Ni SAMPLE, :5 * 10^-8 Torr1st derivative of current (EDC)A1=1KV, A2=200V,A3,A4=Variable10^-9, BW=3, Vac=0.5V Vcoll=250 VFreq=high, Phase shift =+20100SECS 100V SWEEP

RF Presentation to CI SAC 23 Nov 2006 19

Multipactor – prediction of secondary electron emission coefficients

• Dr Rebecca Seviour• Accelrys used to investigate band diagrams of materials

TiN = 1

TiN

Al2O3

Muon Ionisation Cooling for NF & MICE

Need:• 201 MHz Resonant Cavities at 16 MV/w in 4T field• High accuracy measurement of the Eacc

• Dr Rebecca Seviour• 1 x PhD (MICE Phase II)

RF Presentation to CI SAC 23 Nov 2006 21

RF Cavity development

• Dr Rebecca Seviour• 2 x Post Doc’s (NF)

RF Presentation to CI SAC 23 Nov 2006 22

RF Cavity development

Without Magnetic field has achieved 16 MV/m

Electric field Magnetic field Surface currents

Scattering causes losses limits current

limits RF limits acceleration

Metal

Vacuum

Excitation MotionImpurities

RF Presentation to CI SAC 23 Nov 2006 23

We propose to conduct a systematic review of each stage of manufacture.

Investigating the effect each stage has on the surface topology and chemical composition of the surfaces, and ultimately the effect on cavity performance.

• Auger Spectrometry

• Atomic force microscopy

These results will also be compared to theory.

Transport

CodesCavity Q

RF Cavity development

RF Presentation to CI SAC 23 Nov 2006 24

RF Cavity development: Alternatives to EP

Al2O3 suspended in

PH7 Solution.

CMP cheaper & less hazardous than EP.

Only useful on flat areas

Chemical Mechanical Polishing (CMP)

(Rohm and Haas Electronic Materials)

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Ra ~ 0.4 m

Abrasive Flow (AF)

RF Cavity development: Alternatives to EP

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PBG Based Particle Acceleration

• Dr Rebecca Seviour• 2 x Post Doc’s • 2 x PhD’s• 1 x MSc

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• RF Creation

• Particle Acceleration

• Slow-wave structures

• Inverse Cherenkov Acceleration

• Quasi-Crystals/Metamaterials

PBG Based Particle Acceleration

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Selected Publications• Carter RG., ‘Accuracy of microwave cavity perturbation measurements’, IEEE Transactions on Microwave Theory

& Techniques, vol.49, no.5, pp.918-23. (2001)

• Geng RL. Padamsee H. Belomestnykh S. Goudket P. Dykes DM. Carter RG., ‘Suppression of multipacting in rectangular coupler waveguides’, Nuclear Instruments & Methods in Physics Research Section A-Accelerators Spectrometers Detectors & Associated Equipment, vol.508, no.3, pp.227-38. (2003)

• Tahir I., Dexter A.C and Carter R.G., ‘Noise Performance of Frequency and Phase Locked CW Magnetrons operated as current controlled oscillators’, IEEE Transactions on Electron Devices, vol.52, no.9, pp.2096-2103, (2005)

• Dexter A.C. and Seviour R. ‘Rapid Generation of Multipactor Charts by Numerical Solution of the Phase Equation’, J. Phys D: Appl. Phys. vol 38, pp1383-1389, (2005)

• Seviour, R. ‘The Role of Elastic and Inelastic Electron Reflection in Multipactor Discharges’, IEEE Transactions on Electron Devices, vol.52, pp.1927-1930, (2005)

• Geng RL, Goudket P, Carter RG, Belomestnykh S, Padamsee H, Dykes DM, Dynamical aspects of multipacting induced discharge in a rectangular waveguide, Nuclear Instruments & Methods in Physics Research Section A-Accelerators Spectrometers Detectors & Associated Equipment, vol.538, pp.189-205, (2005)

• Tahir I., Dexter A.C and Carter R.G., ‘Noise performance of frequency- and phase-locked CW magnetrons operated as current-controlled oscillators’, IEEE Transactions on Electron Devices Volume 3,  no.7,  pp.1721–1729, (2006)