RF Technology - Lancaster University

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RF Technology

Professor Richard Carter

Lancaster University Engineering Department

23
rd

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

RF Presentation to CI SAC 23 Nov 2006

5

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)

RF Presentation to CI SAC 23 Nov 2006

6

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


RF Presentation to CI SAC 23 Nov 2006

8

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




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 cavity

RF 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

RF Presentation to CI SAC 23 Nov 2006

13

RF Presentation to CI SAC 23 Nov 2006

14

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

RF Presentation to CI SAC 23 Nov 2006

17

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)
100V
150V
200V
300V
400V
Acid cleaned, not outgased
Ni SAMPLE, :5 * 10^-8 Torr
1st derivative of current (EDC)
A1=1KV, A2=200V,A3,A4=Variable
10^-9, BW=3, Vac=0.5V Vcoll=250 V
Freq=high, Phase shift =+20
100SECS 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

Al
2
O
3

Muon Ionisation Cooling for NF & MICE

Need:


201 MHz Resonant Cavities at 16 MV/w in 4T field


High accuracy measurement of the E
acc



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 Motion

Impurities

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


Codes

Cavity Q

RF Cavity
development

RF Presentation to CI SAC 23 Nov 2006

24

RF Cavity development: Alternatives to EP

Al
2
O
3

suspended in
PH7 Solution.

CMP cheaper & less
hazardous than EP.


Only useful on flat
areas

Chemical Mechanical Polishing (CMP)

(Rohm and Haas Electronic Materials)

RF Presentation to CI SAC 23 Nov 2006

25

R
a

~ 0.4

m

Abrasive Flow (AF)

RF Cavity development: Alternatives to EP

RF Presentation to CI SAC 23 Nov 2006

26

PBG Based Particle Acceleration




Dr Rebecca Seviour



2 x Post Doc’s



2 x PhD’s



1 x MSc

RF Presentation to CI SAC 23 Nov 2006

27



RF Creation




Particle Acceleration




Slow
-
wave structures




Inverse Cherenkov Acceleration




Quasi
-
Crystals/Metamaterials

PBG Based Particle Acceleration


RF Presentation to CI SAC 23 Nov 2006

28

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 oscillator
s

, 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)