BCC 41 - 3MeV test stand measurements 1

3 MeV test stand measurement plans

A. Lombardi for the LINAC4 team

10/01/2013

Scope Validate • Source and LEBT design• RFQ design • Chopper

Ultimate goal is to demonstrate

70 mA H-

400 µs

1 Hz

3 MeV

0.4 mm mrad

0.15 deg KeV

Chopped and matched to the DTL

Source 45 keV

RFQ 3 MeV

Chopper

Diagnostic line

LINAC end-to-end

0

20

40

60

80

100

120

140

160

180

0 10 20 30 40 50 60 70 80

Kinetic Energy [MeV] vs. lenght (m)

RFQ DTL 3-50 MeV

CCDTL 50-100 MeV

PIMS 100-160 MeV

2.00E-07

2.50E-07

3.00E-07

3.50E-07

4.00E-07

4.50E-07

0 10 20 30 40 50 60 70 80

Normalised RMS transverse emittance (PI m rad)

x

y

transition

transition

Location and causes of e growth and losses:

LEBT solenoids (divergent beam from the source). 45 keVMEBT transport (abrupt change of phase advance). 3 MeV

BOTH ARE UNAVOIDABLE but they must be controlled

0.00E+00

2.00E+00

4.00E+00

6.00E+00

8.00E+00

1.00E+01

1.20E+01

1.40E+01

1.60E+01

1.80E+01

2.00E+01

0 10 20 30 40 50 60 70 80

aper

ture

/rm

s bea

m si

ze

meters

aperture/rms beam size vs lenght

DTL : FFDD and FODOLEBT RFQ MEBT CCDTL : FODO PIMS : FODO

Emittance 0-3 MeV

2.00E-07

2.50E-07

3.00E-07

3.50E-07

4.00E-07

4.50E-07

5.00E-07

5.50E-07

6.00E-07

0 2 4 6 8 10 12

normalised RMS-Emittance [m.rad] vs lenght

(X,BGX') RMS-Emittance [m.rad]

(Y,BGY') RMS-Emittance [m.rad]

Symmetry x,y in LEBT, if source is symmetric

Losses in the RFQ, emittance decreases

Losses and emittance increase when matching to the DTL

BCC 41 - 3MeV test stand measurements 5

bench

10/01/2013

Spectrometer (0.2 %)Slit and Grid EmittanceToF (calibration)Bunch Shape MonitorHalo Monitor (chopping eff.)TransformersFeshenko

EDMS – 1004908 G. Bellodi

BCC 41 - 3MeV test stand measurements 6

Measurement plan – 1/2

10/01/2013

Stage 1 – after the RFQ 9 parameters : 2 solenoids, RFQ amplitude, 2 quads , 2 steerers

Scan Minimum beam

1) RFQ Transmission Solenoids, RF power Initially I =20 mA (min) Emi= 0.5 (max)

Needs I=70 mAEmi = 0.25 to fully validate.

2) RFQ emittance Solenoids, RF power

3) RFQ energy spread/longitudinal emitt

Solenoids, RF power

NEED TO ACHIEVE TRANSMISSION THROUGH THE RFQ OF 80% TO GO TO THE NEXT STAGE (NOMINAL TRANSMISSION IS 92%)

BCC 41 - 3MeV test stand measurements 7

Measurement plan – 2/2

10/01/2013

Stage 2 – after the chopper30 parameters : stage 1 parameters + 11 quads, 3 RF ampli, 3 RF phases, chopper voltage, 2 steerers

Scan Minimum beam At RFQ input

1) Transmission All parameters Initially I =50 mA (min) Emi= 0.4 (max)

Needs I=70 mAEmi = 0.25 to fully validate.

2) CHOPPING Pencil beamAll quads

3) Transverseemittance4) Longitudinal plane Buncher settings

FULL CHARACTERISATION IS NOT POSSIBLE, BUT GIVE PRIORITY TO THE MORES CRITICAL ITEMS

Pencil beam All elements on Chooper on (top) Chopper off (bottom)

With this we validate :1) Chopper voltage2) Optics

we do not validate : 3) Space charge4) Rise/fall time

MOST IMPORTANT MEAS

BEAM AT THE ws JUST BEFORE THE INLINE DUMP

OP DAY - 26th January 2012 Archamps 9

Measurement 2011 – p from DESY

RFQ acceptance vs. Measured emittance Measured after source vs. Measured at the RFQ input plane and backtracked to the source

BCC 41 - 3MeV test stand measurements 10

Protons• Already discussed – EDMS 1096658 • Measurement with Desy source in proton mode

(2011) gave an excellent insight into LEBT dynamics and solenoid modelling

To be done before protons are usable : • optimise to reach a min of 50-60 mA after the first

solenoid, • measure emittance vs. solenoid settings (5-10) and

back-trace to source input : create a beam for simulating/optimising the whole test stand.

10/01/2013

BCC 41 - 3MeV test stand measurements 11

Sharing the test stand- proposal(change over takes ½ day to 1 day)

• Run in proton mode until the emittance metre has to be dismantled

• Source development till RFQ ready for beam• Share 2:1 between 3 MeV measurements and

source development, over 3 weeks period or as best convenient.

• DO NOT FORGET COMMISSIONING TIME FOR DIAGNOSTICS

10/01/2013

BCC 41 - 3MeV test stand measurements 12

Proposal -

• 3 MeV beam commissioning must be done in 2 sessions/day on the basis 5 days/week . E.g. 7:00- 14:00 and 14-21

• We (BD team) are 3 staff + 3 visitors

• Daily brief meeting with the people on the field + 1 by-weekly meeting in the control room to take decisions – CALLED BY GB

• Need experts available as much as possible (in 2011 we “took it easy” but it took 6 months to measure the LEBT!)

10/01/2013

BCC 41 - 3MeV test stand measurements 13

Something has to give…• Laser stripping measurements ( make sure that BI is made aware)• Halo measurements under different matching• Matching to the DTL • Buncher optimisation • Pencil beam scans • Calibration of TOF vs. spectrometre…….. And many more

10/01/2013

The time presently allocated for commissioning in the tunnel is not sufficient-need 6 months

We should repeat the measurements after the RFQ in the tunnel