1. RF operation2. Beam operation and results

3. SRFQ for high I linacs

Injector 1: Tandem (A < 120, 1÷10 pnA))

Injector 2: PIAVE - all ion species, 20÷200 pnAECRIS - 2 SRFQs and 8 QWRs

ALPI: a boosterfor Tandem andPIAVE

ECRIS

LEBT 3H-BSRFQs

QWRsB

Commissioning of PIAVE with pilot beam 16O3+

has been completed (June 05)

July 6, 05

• Crioline con SRFQsfoto e loro tabella

SRFQ1 SRFQ2

Frequency 80 80 MHz

Length 1,41 0,8 m

Diameter 0,81 0,81 m

Weight 280 170 Kg

∆V_interelectrode 148 280 kVModulated cells 41 13Es,p 25,5 25,5 MV/mEs,p/Ea 10 7.33Bs,p 0,025 0.03 TStored Energy 2,1 3,6 JPdiss (set) 10 10 WQ 1x108 2x108

Focusing ⇐ main quadrupolar ETAcceleration ⇐ small effective EL

modulation of 4 vanes(synchronous with beam bunches)

one modulation period = βλ

NORMAL CONDUCTING∆U ~ 100 kV, Q ~ 104, d.c. < 20%with a few remarkable exceptions

(LEDA: 2.2.MW rf, 100 mA-beam)

SUPERCONDUCTING∆U~ 300 kV, Q~109, d.c. = 100%Motivated by lower rf power (and µA beam) + expertise in cryogenics

(kr)coskz]IAcos2θr[A2Vz)θ,U(r, 010

201 +=

Ideal for β=v/c < 0.05Typically NC, 50-400 MHz

SRF05 – Cornell – July 11, 2005

Radio-Frequency Quadrupoles

1. To reach spec Ea @ Pcav ≤ 10 W): Q vs Ea curve2. To keep frequency locking to M.O. vs slow volume changes (drifts of the

liquid He P) and fast vibrations

SLOW PHe DRIFTS

Mechanical tuner coping with the ∆f/∆t, induced by ∆PHe/∆tCryo-plant operation minimizes ∆PHe/∆t

MICROPHONICS EXCITATIONS

3. Setup for beam acceleration (“classical” RFQ is split into 2, with ext. bunching)4. RFQ alignment on beam axis (better than ± 0.2 mm for good beam transmission)

Rigid mechanical designUse of VCX fast tuners (ANL)Gentle cryo-plant operation

SRF05 – Cornell – July 11, 2005

The main issues of S-RFQs

1,E+07

1,E+08

1,E+09

0 1 2 3 4 5

Eacc [MV/m]

Q

SRFQ1SRFQ2Es,p/Eacc = 10 , 7.33

No VCX fast tuners in the test cryostatSRF05 – Cornell – July 11, 2005

1. Off-line Q-curves in a test cryostat

1,E+07

1,E+08

1,E+09

0 1 2 3 4 5

Eacc [MV/m]

Q

SRFQ1SRFQ2

Frequency window controlled by VCXs: 80 Hz (SRFQ1), 200 Hz (SRFQ2)

SRF05 – Cornell – July 11, 2005

1. On-line Q-curves (loaded by VCX)

0

1

2

3

4

5

6

13:08:15 13:09:42 13:11:08 13:12:35 13:14:01Time of the day

Phas

e a

nd a

mpl

itude

err

or [V

]

-60

-40

-20

0

20

40

6024 s 8 s, 5 s

6 s

∆P

/ ∆t [

mba

r/min

]

80% of nominal field

SRFQ1 with VCX

Mechanical tuners react at 2 Hz/s(corresponding to ∆P/∆t =2.5÷3 mb/min)SPECS – 5 mb/min

June

2004

, a 6

min

sam

ple

SRF05 – Cornell – July 11, 2005

2. Phase locking difficult before optimizingthe cryo-plant parameters

2°

200

220

240

260

280

9.00 10.00 11.00 12.00 13.00 14.00Time of the day

He

pres

sure

[mb]

up to30 mb/min

June 2004

SRF05 – Cornell – July 11, 2005

200

220

240

260

280

9.00 10.00 11.00 12.00 13.00 14.00

Time of the day

He

pres

sure

[mb]

< 1÷2 mb/min

SRF05 – Cornell – July 11, 2005

2. P changes smaller in range and speedafter optimizing the cryo-plant parameters

Careful setup of the P.I.D. parameters controllingcryostat valves opening (continuous filling mode)Control of additional heating or increased production rate of liquid He vs cavity rf power.

234

235

236

237

238

239

13.15 13.30 13.45 14.00 14.15 14.30

Time of the day

He

pres

sure

[mb]

0,00

0,50

1,00

Phas

e-A

mpl

itude

err

or [V

]

June

2005

, a 6

0 m

insa

mpl

e

SRFQ2 VCX fast tuner window 200 Hz (specs)SRF05 – Cornell – July 11, 2005

2. ϕ & A errors on SRFQ2 after optimizationof the cryo-plant parameters

231

232

233

234

235

236

13.15 13.30 13.45 14.00 14.15 14.30

Time of the day

He

pres

sure

[mb]

0,0

0,5

1,0

1,5

2,0

2,5

Phas

e - A

mpl

itude

err

or [V

]

June

2005

, a 6

0 m

insa

mpl

e

SRFQ1 VCX fast tuner window 80 Hz (specs 200 Hz)SRF05 – Cornell – July 11, 2005

2. ϕ & A errors on SRFQ1 after optimizationof the cryo-plant parameters

Vibrations induced bythe slowly tuned end-plates

B SRFQ1 SRFQ2Lens Lens

Si

FC

3. Setup for beam acceleration(“classical” RFQ is here split in 2, with ext. bunching)

4. RFQ alignment on beam axis (better than ± 0.2 mm for good beam transmission)

SRF05 – Cornell – July 11, 2005

SRFQs: beam-related aspects

0

2

4

6

8

10

-180 -90 0 90 180

φSRFQ2 - φSRFQ1

Bea

m E

nerg

y [M

eV]

0

10

20

30

40

T [%

]

B SRFQ1 SRFQ2Lens Lens SiFC

SRF05 – Cornell – July 11, 2005

3. Setup of the relative phasebetween the SRFQs

05

101520253035404550

3,0 4,0 5,0 6,0 7,0 8,0 9,0 10,0Energia [MeV]

Yiel

d

02040506070

0

50

100

150

200

250

300

3,0 4,0 5,0 6,0 7,0 8,0 9,0 10,0Energia [MeV]

Yiel

d

160170180190200220

B SRFQ1 SRFQ2Lens Lens

Si FC

SRF05 – Cornell – July 11, 2005

3. Energy plots at varyingϕSRFQ2 - ϕ SRFQ1

0123456789

10

0 90 180 270 360

φSRFQ2-φSRFQ1

Theo

retic

al a

nd m

easu

red

out

put e

nerg

y [M

eV]

∆φ = 137°(theoretical 0°)

T ~ 30 %, as expected from the theoryT ~ 30 → 68% (expected : 70%) after switching on the 3H-buncher

SRF05 – Cornell – July 11, 2005

3. ϕSRFQ2 is scanned, while ϕSRFQ1 = k

Specs: ± 0.2 mm between SRFQ1 and SRFQ2 and between SRFQsand injection line for good T

0,00

20,00

40,00

60,00

80,00

-2 -1 0 1 2

y - misalignment [mm]Tr

ansm

issi

on [%

]

The quad in front of SRFQsis moved vertically and horizontally around theSRFQs’ axis

4. Control of alignment tolerances

ECRIS

LEBT 3H-BSRFQs

QWRsB

to ALPI

booster

Emittance box

1.

2. 3. 4.

Longitudinal emittanceHor & Ver emittances

E

t

1. 2. 0.08÷0.1 mm mrad3. 0.1÷0.2 mm mradth. 0.1 mm mrad

3. 2.3 keV ns /A(th. 0.5 keV ns /A)

Transmission1.► 2. 90% 2. ► 3. 68%3. ► 4. 85%

SRF05 – Cornell – July 11, 2005

July 6, 05

SRFQ1&2 so far accelerated beams for~ 600 hours (since Nov 04)July, 05: first injection into ALPI boosterOct, 05 – Jan, 06: beam tests on bothPIAVE +ALPI with heavier beams (131Xe18+)Goal: PIAVE+ALPI operation with approved NP experiments from Feb, 06

ALPI

PIAVE

July 18-20, 05

SRF05 – Cornell – July 11, 2005

• 5 mA of d & p to 40 MeV cw (SPES)• Operate at subharm. of 352 MHz

(EURISOL) – 88 MHzεx,y, RMS,n= 0.1 mm mradεl,RMS = 0.1 deg MeV/AE = 1.3 MeV/A

⎟⎟⎠

⎞⎜⎜⎝

⎛=

02 Rmc

eVB λ

• V (between vanes) ~ 280 kV (3 times higher than NC), large λ

• R0 can be increased, transmissiongreatly improves and contrsuctiontolerances are relaxed

• Higher EA, compact structure

2

02 ⎟⎟

⎠

⎞⎜⎜⎝

⎛=

RmceVB λ

2mceVkNλε = βλ

eVAkEA =

Pros of the SRFQ option

SRF05 – Cornell – July 11, 2005

A SRFQ for a high current linac

kW13Beam loadingGauss0±0 ,25B within ±1 mm from joint

%± 2Voltage flatness

Gauss300Bs,p

MV/m20,7Es,p

MHz94,2Dipole mode

MHz88Frequency

1.3 m

SRF05 – Cornell – July 11, 2005

HFSS

A 88 MHz PIAVE-likeSRFQ

SRFQs work and accelerate beams!