MP - HIPPI General meeting, Abingdon October 28-30, 2005

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CCDTL design and CCDTL design and prototype measurementsprototype measurements

M. Pasini, Abingdon September 28th, 2005

MP - HIPPI General meeting, Abingdon October 28-30, 2005

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CONTENTS:CONTENTS:

1. CCDTL structure, general concept.

2. Beam Parameters

3. Layout design philosophy

4. Optimized layout

5. Frequency error study

6. CCDTL prototype – Mechanical remarks

7. Low level measurements

8. Conclusions

MP - HIPPI General meeting, Abingdon October 28-30, 2005

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Cavity structureCavity structure

MP - HIPPI General meeting, Abingdon October 28-30, 2005

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Why CCDTL?Why CCDTL?

1. In the energy range 40-90 MeV the velocity of the particle is high enough to allow long drifts between focusing elements so that…

2. …we can put the quadrupoles lenses outside the drift tubes with some advantage for the shunt impedance but with great advantage for the installation and the alignment of the quadrupoles…

3. the final structure becomes easier to build and hence cheaper than a DTL.

4. The resonating mode is the /2 which is intrinsically stable.

MP - HIPPI General meeting, Abingdon October 28-30, 2005

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ZTZT22 Curve Curve

0

10

20

30

40

50

60

3 13 23 33 43 53 63 73 83

Energy (MeV)

ZT

2 (M

Oh

m/m

)

DTL tank1

DTL tank2

DTL tank3

CCDTL

MP - HIPPI General meeting, Abingdon October 28-30, 2005

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Beam ParametersBeam Parameters

Particle H-

Initial energy 40 MeV

Final energy 90 MeV

Beam Intensity 40 mA (peak)

Duty Cycle (LINAC 4)

0.08 %

Max Duty Cycle 14 %

Frequency 352.2 MHz

Focusing Channel

F0D0

MP - HIPPI General meeting, Abingdon October 28-30, 2005

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A bit of Definitions…A bit of Definitions…

Single Accelerating CCDTL tank

1 Power coupler / klystron

Module

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Layout design philosophyLayout design philosophy

1. Every tank has 3 accelerating gaps (2 drift tubes).

2. The klystron feeds a module that is made out of 3 tanks.

3. The level of the accelerating field from module to module is decreasing in order to have a even power load per klystron.

4. Synchronous phase is -20 deg.

5. Distance between tanks is constant (250 mm). This allow insertion of a quadrupole.

MP - HIPPI General meeting, Abingdon October 28-30, 2005

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CCDTL optimized LayoutCCDTL optimized Layout

Klystron[#]

Cavity/Kly.[#]

Gradient[MV/m]

Power/Kly.[kW]

Energy[MeV]

Max Kilpatrik[#]

1 3 3.89 800 46.4 1.62

1 3 3.608 800 52.8 1.56

1 3 3.37 800 59.2 1.50

1 3 3.19 800 65.7 1.46

1 3 3.053 800 72.2 1.42

1 3 2.945 800 78.7 1.39

1 3 2.866 800 85.2 1.36

1 3 2.805 800 91.7 1.34

Tot. Klystron[#]

Tot. cavity[#]

Average Grad.[MV/m]

Tot. Power[MW]

Tot. Length.[m]

8 24 3.264 6.4 25.2

MP - HIPPI General meeting, Abingdon October 28-30, 2005

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Voltage and Phase error Voltage and Phase error studystudy

Results of a simulation of voltage and phase error for the synchronous particle with V/V = 0.5% rms and = 0.5 deg rms

Ref. M. Pasini, CARE/HIPPI Document-2005-006

MP - HIPPI General meeting, Abingdon October 28-30, 2005

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Coupling coefficientsCoupling coefficients

0 5 10 15 20 250.006

0.0065

0.007

0.0075

0.008

0.0085

0.0098.7 10

3

6.087 103

ki

2

240 i

0 5 10 15 20 250.15

0.2

0.25

0.3

0.35

df i

i

9‰

6‰

Co

upl

ing

fact

or k

Cavity number (#)

MP - HIPPI General meeting, Abingdon October 28-30, 2005

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PSPICE SimulationPSPICE Simulation

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Frequency

349MHz 350MHz 351MHz 352MHz 353MHz 354MHz 355MHz 356MHz... V(TX5:1) ... V(R7:2) ... V(TX2:1)

1.0mV

1.0V

1.0KV

MAXr(V(TX2:1), 352e6, 352.4e6)48 50 52 54 56 58 60 62

0

10

20Percent

SEL>>

n samples = 100n divisions = 30

mean = 55.7097sigma = 2.51049

minimum = 50.473610th %ile = 51.8802

median = 56.248790th %ile = 58.4478

maximum = 58.7493

MP - HIPPI General meeting, Abingdon October 28-30, 2005

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RMSRMS fieldfield errorserrors

0.80%

0.90%

1.00%

1.10%

1.20%

1.30%

1.40%

0.005 0.0055 0.006 0.0065 0.007 0.0075 0.008 0.0085

coupling coefficient (k)

fiel

d e

rro

r (%

)

f = ±50 kHz in all the 5 resonating cells

MP - HIPPI General meeting, Abingdon October 28-30, 2005

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CCDTL PrototypeCCDTL Prototype

1. A prototype consisting in 2 half accelerating cells and a full coupling cell has been built and assembled.

2. The delivery of the prototype was late by 6 months, mainly due to fabrication problems (steel quality) and copper plating preparation. (Finally successful at the 2 attempt).

MP - HIPPI General meeting, Abingdon October 28-30, 2005

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1st Half-tank (accelerating)

Coupling cell

2nd Half-tank (accelerating)

MP - HIPPI General meeting, Abingdon October 28-30, 2005

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MP - HIPPI General meeting, Abingdon October 28-30, 2005

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MP - HIPPI General meeting, Abingdon October 28-30, 2005

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MP - HIPPI General meeting, Abingdon October 28-30, 2005

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MP - HIPPI General meeting, Abingdon October 28-30, 2005

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MP - HIPPI General meeting, Abingdon October 28-30, 2005

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MP - HIPPI General meeting, Abingdon October 28-30, 2005

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Low Level MeasurementsLow Level Measurements

After single cell tuning

mode Freq (MHz) Q

0 350.654 12000

/2 352.233 21000

353.761 13000

K=0.88% coupling coefficient

The measured Q-value is only 61 % with respect to Superfish.

The cavity however was not properly closed and the tuners used were made of aluminum.

MP - HIPPI General meeting, Abingdon October 28-30, 2005

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Low Level MeasurementsLow Level Measurements

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Wave guide coupling Wave guide coupling factor measurementfactor measurement

Distance between coupling iris and short circuit.

-50 0 50 100 150 200 250 300 350 400 450 500l (mm)

0.00

0.20

0.40

0.60

0.80

1.00

1.20

fit results

max=1.04525l=-1.48206=1344.97

MP - HIPPI General meeting, Abingdon October 28-30, 2005

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Summary / ConclusionsSummary / Conclusions

1. A new reference layout has been calculated, the section length is now 25m (20% shorter then the previous layout)

2. Validation of the 20 degrees synchronous phase layout has been achieved.

3. Future layout will include a special subsection where the fields in the last 2 modules will be raised up in order to allow a smooth transition in term of longitudinal phase advance. This will imply the addition of one more klystron.

MP - HIPPI General meeting, Abingdon October 28-30, 2005

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Summary / ConclusionsSummary / Conclusions

4. Calculation on the frequency error leads to tolerable error in the fields.

5. The prototype is completely assembled. A low level measurement campaign has been performed and results are reported.

6. Final assembly and tuning is foreseen in October and high power test in November.