1 the saraf accelerator commissioning dan berkovits on behalf of saraf team soreq nrc seminar @ fnal...

1

The SARAF accelerator commissioning

Dan BerkovitsOn behalf of SARAF team

Soreq NRC

Seminar @ FNALFebruary 10, 2011

D. Berkovits Feb 10 2011 @ FNAL2

SARAF – Soreq Applied Research Accelerator Facility• To enlarge the experimental nuclear

science infrastructure and promote research in Israel

• To develop and produce radioisotopes primarily for bio-medical applications

• To modernize the source of neutrons at Soreq and extend neutron based research and applications


SARAF Accelerator ComplexParameter Value Comment

Ion Species Protons/Deuterons M/q ≤ 2

Energy Range 5 – 40 MeV

Current Range 0.04 – 2 mA Upgradeable to 4 mA

Operation 6000 hours/year

Reliability 90%

Maintenance Hands-On Very low beam loss

Phase I - 2009 Phase II - 2016


SARAF Accelerator

PSM – Prototype Superconducting Module


SARAF phase I linac – upstream view

A. Nagler, Linac-2006 C. Piel, EPAC-2008 A. Nagler, Linac-2008 I. Mardor, PAC-2009L. Weissman, Linac 2010

6

Beam lines downstream

the linac

PSM

Beam dump

target


beam

RF power supply2.45 GHz

Plasma chamber

High voltage

extractor

Magnetic solenoid

Vacuum pump 5x10-6 mbar

RF Waveguide& DC-breaker

Focusing solenoid

ECR Ion Source (ECRIS)C. Piel EPAC 2006

F. Kremer ICIS 2007

K. Dunkel PAC 2007

extraction

electrodes20 kV/u

107 mm

gas inlet 1 sccm

RF power 800 W

magnetic coils on ground

cooling water

insulator


LEBT – emittance measurement

wireslitaperture

P. Forck JUAS 2003

5 mA proton beam optics

RFQ entranceECR

C. Piel EPAC 2006

F. Kremer ICIS 2007

K. Dunkel PAC 2007

ECR

magnetic mass

analyzer

FC

aperture


EIS: measured emittance values

ParticlesBeam current

ProtonsX / Y

H2+

X / YDeuterons

X / Y

5.0 mA 0.20 / 0.17 0.34 / 0.36 0.13 / 0.12

2.0 mA 0.13 / 0.13 0.30 / 0.34 0.14 / 0.13

0.04 mA 0.18 / 0.19 0.05 / 0.05

erms_norm._100% [p mm mrad]

Specified value = 0.2 / 0.2 [p mm mrad]

EIS has been in routine operation since 2006

• H2+ planned for mimicking deuterons

• Results due to non-optimized ECR and molecular breakup


SCUBEEx Analysis

0

0.02

0.04

0.06

0.08

0.1

0.12

0 1400 2800 4200 5600 7000Exclusion Ellipse SAP

No

rm. R

MS

Em

it.

-30 -10 10 30-50

-30

-10

10

30

x [mm]

x' [m

rad

]

Elliptical Exclusion

0

0.05

0.1

0.15

0.2

0.25

0.3

0 1400 2800 4200 5600 7000Exclusion Ellipse SAP

No

rm. R

MS

Em

it.

aperture cut to 5.0 mA

deuterons

6.1 mAopen

aperture

deuterons emittance results

-30 -10 10 30-50

-30

-10

10

30

x [mm]x' [m

rad

]

p mm mrad

B. Bazak JINST 2008

emittance analysis with the SCUBEEx code by M. P. Stockli and R.F. Welton, Rev. Sci. Instr. 75 (2004) 1646

2D plot current scale is enhanced in order to present the tail


LEBT – emittance measurement

wireslitaperture

P. Forck JUAS 2003

5 mA proton beam optics

RFQ entranceECR

C. Piel EPAC 2006

F. Kremer ICIS 2007

K. Dunkel PAC 2007

ECR

magnetic mass

analyzer

FC

aperture

12

Use neutrals for tune LEBTx-x’ y-y’

Idipole=38.65 A

Idipole=38.95 A

Idipole=38.80 A

L. Weissman et al.linac 2010 TUP74


On site 2006

P. Fischer EPAC 2006

In factory 2005

176 MHz Radio Frequency Quadrupole


• Parting from the linear relation indicates onset of dark current due to poor conditioning

• All 4 RFQ pickups showed similar results

RFQ power gain vs. forward power

0

50

100

150

200

250

300

0 50 100 150 200 250 300

FPower (kV)

Pic

kup

V^

2(kW

)

4-Jul

9July

10July

Linear

Forward power (kW)

A. Nagler et al., LINAC08

RFQ voltage squared as a function of RFQ input power

deuterons

protons

For 3 MeV Deuterons:65 kV @ 176 MHz

1.6 Kilpatrick ~ 255 kW CW w/o beam

65 kW/m

Input Power [kW]Duration

[hrs]

190( CW) 12

210( CW) 2

240( CW) 0.5

260( DC = 80% @ 440 Hz)

0.5

2008

15

Non-linearity of voltage response, High x-ray background

Discharge between the back rods and the stems supporting neighboring rods

Discharge between the rods and stems

In spring 2009 the rods were modified locally to reduce the parasitic fields.

This solved the problem of discharge.

I. Mardor, PAC 2009L. Weissman, Linac 2010J. Rodnizki, Linac 2010


Burning of tuning blocks

Contact springs of tuning blocks were burned twice

New design : massive silver plate for better current and thermal conductivity, mechanical contact with stems by a splint system


Melting of plunger electrode

The low-energy plunger electrode has been melted.

It was verified that this was not due to a resonance phenomenon.

New design: plunger was reduced by size ( twice less thermal load), cooling capacity was improved (the plunger and cooling shaft made from one block)

J. Rodnizki et al., Linac 2010, TUP095


Another RFQ hot spots

Further RFQ temperature mapping showed additional problematic regions:

1. the area of the break of tank cooling line especially in the vicinity of the coupler this problem is well understood by simulation, external cooling blocks were installed 2. The region closed to high energy end this is not understood yet and has to be studied

A fan was install in front of the coupler

J. Rodnizki et al., Linac 2010, TUP095


D. Berkovits Feb 10 2011 @ FNAL19 19

MPCT

wire scanners

58 mmTa aperture

Setup for RFQ characterization

4 m

RFQ

ECR

D-plate

Beam dump



Proton energy at RFQ exit by TOFBeam Energy Measurement using TOF

between 2 BPMs sum signals, 145 mm apart,

E = 1.504 ± 0.012 MeV C. Piel PAC 2007

Button pickup for 2 mA pulse and

15 mm bore radius gives a

signal high above noise.

Bunch width measured at

b=0.056 is larger than the predicted value due to the induced charge broadening.


Approximated rms eZ extracted from protons bunch width measurements

0

15

30

45

60

75

90

55 60 65 70 75

power RFQ [kW]

ez )RFQ( [pi deg keV]1s at FFC1 [deg]1s at FFC2 [deg]s_f at RFQ [deg]s_E at RFQ [keV]

Specified rms eZ = 120 p deg keV Value for simulations = 74 p deg keV

C. Piel EPAC 2008


Protons current downstream RFQ vs. RFQ forward power for 3 mA injection

MPCT current

sum of 4 BPM current signals

0.0

0.5

1.0

1.5

2.0

2.5

45 50 55 60 65 70 75

RFQ power (PS forward) [kW]

Be

am c

urr

ent

D-Plate_MPCT [mA]

A_MBPM1 [V_p]

A_MBPM2 [V_p]

4D-WB simulation [mA]

J. Rodnizki et al. EPAC 2008

Uni

ts a

re in

the

lege

nd

70% transs.

Specified transmission=90%


Deuterons beam (through a detuned PSM)

60% transs.

DF=10-4

Specified transmission=90%

24

After improving field homogeneity observe much smaller RFQ power effects

RFQ steering effects

0

10

20

30

40

50

60

70

80

90

100

50 52.5 55 57.5 60 62.5 65 67.5 70 72.5

RF power (kW)

Tra

ns

mis

sio

n (

%)

Apr-2010 Nov-2009

Profile X

-2

-1

0

1

2

3

4

5

6

7

-12.5 -10 -7.5 -5 -2.5 0 2.5 5 7.5 10 12.5

Position (mm)

Cu

rre

nt

(au

. Un

.)

61 kW

56 kW

53 kW

Profile X

-1

0

1

2

3

4

5

-12.5 -10 -7.5 -5 -2.5 0 2.5 5 7.5 10 12.5

Position (mm)

Cu

rre

nt

(au

. un

.)

62 kW

56 kW

54 kW

Nov 2009

Apr 2010

D. Berkovits Feb 10 2011 @ FNAL


Prototype SC Module (PSM)General Design:• Houses 6 HWR and 3

superconducting solenoids• Accelerates protons and

deuterons from 1.5 MeV/u on• Very compact design in

longitudinal direction• Cavity vacuum and insulation

vacuum separated

M. Peiniger, LINAC 2004

M. Pekeler, SRF 2003

M. Pekeler, LINAC 2006

2500 mm


HWR – Basic parameters• f = 176 MHz & bandwidth ~ 130 Hz

• height ~ 85 cm high

• Optimized for b=0.09 @ first 12 cavities (2

modules)

b=0.15 @ 32 cavities (4 modules)

• Bulk Nb single wall 3 mm (in SS vessel)

• Epeak, max = 25 MV/m & Epeak / Eacc ~ 2.9

• Q0 ~ 109 @ 4.45 K

• Designed cryogenic Load < 10 W (@Emax)

• Measured response to pressure = 57 Hz/mbar


HWR measured fields and dissipated power

C. Piel et al. EPAC 2008

A. Perry et al. SRF 2009

At Accel (single cavity) At Soreq (inside PSM)

Target values 60 W @ 4.5 K for 25 MV/m

dynamic loss

Closed loop operation

with a voltage controlled oscillator

(VCO)

Cavity # VerticalTest

Before Processing

After He Processing

25 MV/m

20 MV/m

25 MV/m

20 MV/m

25 MV/m

1 7.3 1.9 7 2.2 5.5

2 7.3 3.0 6.3 4.8 8.7

3 6.3 12.3 16.8 7.0 14.8

4 6.3 11.1 --- 3.9 10.6

5 5.5 5.4 15.1 3.3 8.8

6 7.3 9.6 --- 5.4 10.7

total 40 43.3 --- 26.6 59.1

28 D. Berkovits Feb 10 2011 @ FNAL

PSM Helium distribution system

beam


Setup with Diagnostic plate (D-Plate) for PSM beam commissioning

L. Weissman DIPAC 2009

SARAF Phase I

ECRLEBT

RFQ

PSM

D-plateBeam dumps


Beam operation through the PSM• First proton beam was delivered through the PSM in

November 2008

• Accelerator parameters were set according to beam dynamics simulations )using TRACK - ANL(

• In August 2009 beam was accelerated using all cavities

DF I )mA( E )MeV(

1×10-4 * 2 4.0 protons

CW 1.4 3.2

1×10-4 * 0.5 4.5 deuterons* 100 msec pulse, 1 Hz

I. Mardor et al., SRF 2009

Microphonics measurements* HWRs are extremely sensitive to He pressure fluctuations (60 Hz/mbar)

Detuning signal is dominated by the Helium drift

Detuning sometimes exceeds +/-200 Hz (~ +/-2 BW).

100 110 120 130 140 150 160 170 180 190 200-100

-80

-60

-40

-20

0

20

40

60

80

100

Time[Sec]

Fre

quen

cy D

etun

ing

[Hz]

Frequency Detuning

* Performed in collaboration with J.Delayen and K. Davis )JLab(


Cavity Tune*

Piezoelectric actuator provides fine tuning of the resonance frequency

Range reduction of the piezoelectric elementsWere subsequently replaced

Stepper motor is used for coarse tuning.Stepper motor movement induces instabilities and is therefore disabled during RF operation

* Performed in collaboration with J.Delayen and K. Davis )JLab(

600 700 800 900 1000 1100 1200 1300 1400700

750

800

850

900

950

1000

1050

1100

Piezo Amplifier applied voltage[scaled]

Fre

quen

cy d

etun

ing[

Hz]

Tuner Response Curve

1st cycle2nd cycle

Response of the fine tuner is highly non-linear



phase probe 1

phase probe 2

x/y wire scanners

Faraday cup

FFC 1

FFC 2

MPCT

x/y slit scanners

beam halomonitor

1.18 m

doublet

VAT beam dump BPM1

BPM2

D-Plate for commissioning



-7 1 8-12

-6

0

7

X [mm]

X' [m

rad

]

Scanned area

Transversal emittance• Protons at 2.2 MeV• e~0.15 p mm mrad

rms norm. out of an area excluded the satellite peak

beam

-

-

-

-

- -

X' [m

rad]

X [mm]

1.019999977-1.029500008

0.999999978-1.019999977

0.979999978-0.999999978

0.959999979-0.979999978

0.939999979-0.959999979

0.919999979-0.939999979

0.89999998-0.919999979

0.87999998-0.89999998

0.859999981-0.87999998

0.839999981-0.859999981

0.819999982-0.839999981

0.799999982-0.819999982

0.779999983-0.799999982

0.759999983-0.779999983

0.739999983-0.759999983

0.719999984-0.739999983

0.699999984-0.719999984

0.679999985-0.699999984

0.659999985-0.679999985

0.639999986-0.659999985

Colors chosen to enhance background


BeamSi det 45°

Si det 100°

Au foil

LiF crystals

target ladder

target ladderdrive

targetload-lock

mini FC

I. Mardor et al, LINAC 2006 L. Weissman et al, DIPAC 2009

300 mg/cm2 gold foilglued on graphite frame

Beam energy at the Halo Monitor

Energy measurements are possible because FFC and beam dynamics simulation show that the energy distribution on the beam side is similar to the core


Proton beam energy measurement using Rutherford scattering (RS)

Typical spectrum without cavity voltages )RFQ only(. Background )removed foil( was subtracted.

0

100

200

300

400

500

600

0 200 400 600 800 1000 1200 1400 1600 1800 2000

Energy (keV)

Pulser peakresolution 6.6 keV1.5 MeV peak

used for calibration

Possibly doubly scattered particles

Au foil: 0.3 mg/cm2

Foil rotated by 45°Si detector at 45°


Proton beam energy measurement using Rutherford scattering

0

100

200

300

400

500

600

1400 1420 1440 1460 1480 1500 1520 1540 1560 1580 1600

Energy (keV)

Gaussian fit: FWHM = 18 keV

The low energy tail is most probably enhanced due to rise time of RFQ voltage pulse )Si detector not gated(. This is supported by beam dynamics simulations.

Width includes:• Detector resolution )<12 keV(• Scattering in Au foil• Beam energy width )slide 19(


Calibrating HWR#4

2

2.05

2.1

2.15

2.2

2.25

2.3

0.25 0.3 0.35 0.4 0.45 0.5 0.55

Applied Voltage [MV]

Ene

rgy

[MeV

]

E/u simulated

E/u ToF

E/u Si

Protons 2 mARFQ 56 kW

Phase )deg(

Vacc )kV(

HWR

-95 177 1

0 100 2

20 470 3

-30 4


0

20

40

60

80

100

120

-150 -100 -50 0 50 100

RS

Spec

trum

Std

[keV

]

HWR6 Phase[deg]

0 2000 40000

10

20

Energy[keV]

Cou

nts

0 2000 40000

50

100

Energy[keV]C

ount

s

0 2000 40000

10

20

Energy[keV]

Cou

nts

0 2000 40000

50

100

Energy[keV]

Cou

ntsPhasing of cavity HWR#6

Protons 2 mA

A. Perry et al. SRF 2009

SARAF today

EIS

LEBT RFQPSM

MEBTPhase I - 2010

D-plate

Beam line - 2010 targets

Beam dumps

Situation in beginning of 2011:

The turn-key concept did not work. At present work is done mostly by the local team.

The local team and its expertise grew significantly Phase I is not commissioned yet to full specs (CW deuterons), but accelerator is operational

The concept of Phase II is being developed in collaboration with accelerator laboratories


Beam lines downstream

the linacfor in vacuum target studies

PSM

Beam dump

target

H. Hirshfeld et al. NIM A 2006E. Lavie et al. INS23 2006

I. Silverman et al., NIM B261 2007M. Hass et al., J. Phys. G 2008

T. Hirsh et al., PoS 2009G. Feinberg et. al., Nucl. Phys. A 2009Halfon et. al., Appl Radiat Isot. 2009

M. Paul et al. US patent WO/2009/007976S. Vaintraub et al. INS25 2010

PSM

D-plate

VAT-BDTungsten Metal -BD

Experience with the Tungsten Beam dump

The beam dump 250 micron Tungsten sheet fused to a water cooled cooper plate. Up to 20 kW, no activation is expected.Visual inspection reveal strong blistering effects.

Improve diagnostics tools: temperature mapping radiation mapping (gamma, neutrons) better vacuum control including RGA segmented collimator on-line visual inspection



SARAF Phase II simulations with error analysis

Simulations shown in next slide:• 4 mA deuterons at RFQ

entrance. • Last macro-particle=1

nA

Errors are double than in: J. Rodnizki et al. LINAC 2006, M. Pekeler HPSL 2005

B. Bazak et al., Submitted for Publication

J. Rodnizki et al., HB2008


Deuteron beam envelope radius at SARAF SC Linac

RFQ exit3.4 mA deuterons

32k/193k particles in core/tailLast macro-particle = 1 nA

General Particle Tracer 2.80 2006, Pulsar Physics S.B. van der Geer, M.J. de Loos http://www.pulsar.nl/

rmax

rRMS

nominal

200 realizations 70 realizations

Bore

Solenoids 19

B. Bazak et al., Submitted for Publication

J. Rodnizki et al., HB2008

Tail emphasis simulations


Beam loss criterion

SPIRAL2 [4], IFMIF [6]

* Beam loss criterion which will yield the specified dose rate along SARAF SC linac

[1] J. Alonso, "Beam loss working group report", The 7th ICFA mini-workshop on high intensity high brightness hadron beams, Lake Como, Wisconsin, September 1999.

[2] R. A. Hardekopf, "Beam loss and activation at LANSCE and SNS", The 7th ICFA mini-workshop on high intensity high brightness hadron beams, Lake Como,Wisconsin, September 1999.

[4] T. Junquera et. al., “Status of the construction of the SPIRAL2 accelerator at GANIL”, Proc. Of LINAC08, Victoria, BC, Canada, 2008.

[5] M. Sugimoto and H. Takeuchi, “low activation material applicable to the IFMIF accelerator”, Journal of Nuclear Material, 329-333 )2004( 198-201.

[6] P. A. P. Nghiem et. al., “Parameter design and beam dynamics simulations for the IFMIF-EVEDA accelerators”, Proc. Of LINAC08, Victoria, BC, Canada, 2008.

IFMIF [5]

Unconstrained "hands-on“ [1,2] for SARAF SARAF old

0 5 10 15 20 25 3010

-2

10-1

100

101

102

103

Position along SARAF SC linac )m(

Allo

w lo

sses

for

han

ds o

n m

aint

enan

ce )

nA/m

(

Calculated losses10 mrem/h

2 mrem/h

1 W/m

1 nA/m50/20/5 nA/m

*

*

Halfon et al., 2009

RFQ exit

HEBT

46

People involvedSARAF team (including students, advisers and partially affiliated personal ) : A. Nagler (until 2008), I. Mardor, D. Berkovits,A. Abramson , A. Arenshtam, Y. Askenazi, B. Bazak (until 2009), Y. Ben-Aliz, Y. Buzaglo, O. Dudovich, Y. Eisen, I. Eliyahu, G. Finberg, I. Fishman, I. Gertz, A. Grin, S. Halfon, D. Har-Even D. Hirshman, T. Hirsh, A. Kreisel, D. Kijel, G. Lempert, A. Perry, R. Raizman (until 2010), E. Reinfeld, J. Rodnizki, A. Shor, I. Silverman, B. Vainas, L. Weissman,Y. Yanay (until 2009).

RI&Varian /(former ACCEL): H. Vogel, C. Piel, K, Dunkel, P. Von Stain, M. Pekeler, F. Kremer, D. Trompetter, many mechanical and electrical engineers and technicians

NTG/ Frankfurt Univ: A. Bechtold, Ph. Fischer, A. Schempp, J. Hauser

Cryoelectra : B. Aminov, N. Pupeter, …


END


MEBT: Overview

Main components:

• Three quadrupols (31 T/m) with steering magnets

• Two diagnostic chamber • Two x/y wire scanners• Three pumps and one gauge• Two 4-button BPMs

• Position• Phase• Current


MEBT

RFQD-plate

pumpspump

wire scanner 1

wire scanner 2

BPM1BPM2

beam

650 mm


phase probe 1

phase probe 2

x/y wire scanners

Faraday cup

FFC 1

FFC 2

MPCT

x/y slit scanners

beam halomonitor

1.18 m

doublet

VAT beam dump BPM1

BPM2

D-Plate for commissioning



RFQ RF conditioning

Input Power [kW] Duration [hrs]

190( CW) 12

210( CW) 2

240( CW) 0.5

260( DC = 80% @ 440 Hz) 0.5

Melted tuning plate after extraction

beam

Melted area

I. Mardor et al., PAC 2009

I. Mardor et al., SRF 2009

60 mm


RFQ: Protons bunch profile measurements

Measurement results are backed up by simulations

)TRACK(

Rodnizki et al. EPAC 2008

C. Piel PAC 2007

Wire scan profiles

FFC time profiles

-4 -2 0 2 40

0.2

0.4

0.6

0.8

1

position )cm(

coun

ts

meanm 0.00 cm

FWHMs 0.40 cm

FWHMm 0.46 cm

-4 -2 0 2 4position )cm(

meanm 0.00 cm

FWHMs 3.70 cm

FWHMm 3.57 cm

0.0

0.2

0.4

0.6

0.8

1.0

1.2

0 100 200 300

proton relative phase )deg(

curre

nt )a

rb.(

gauss fit

simulated

0 100 200 300

proton relative phase )deg(

gauss fit

gauss fitmeasurement

32.5 kV 63.5 kW

FFC1 FFC1

32.0 kV

61.5 kW

MEBT Entrance

D-Plate

Simulation Measured


RFQ Conditioning – status• Several hundred conditioning hours for two years• Conditioning schemes

– Set maximum power and increase duty cycle– Set CW duty cycle and increase power

• Special actions to improve conditioning rate:– Rounding of sharp edges of rods bottom part– Cleaning of rods– Installation of circuit for fast recovery after sparks– Baking at 75°C for a week in vacuum and for a day with

flowing nitrogen– Add a 3rd pump to the two existing TMPs

Reach field for deuterons and hold CW for minutes


RFQ field flatnessFollowing the modification of electrodes the frequency correction procedure (moving and removing of tuning plates) changed the field flatness along the 39 RF cells .

This may lead to a transmission reduction and consequently to emittance reduction

LEBT D-plate transmission = 40%Typical LEBT norm. rms emittance ~ 0.2 p mm mrad D-plate=0.15 p mm mrad + satellite


Phasing of resonator HWR#1

1350

1400

1450

1500

1550

1600

1650

-260 -230 -200 -170 -140 -110 -80 -50 -20 10

Phase HWR1 (deg)

En

erg

y (M

eV)

TOF

RBS

Simulations

0

2

4

6

8

10

12

14

16

18

-260 -230 -200 -170 -140 -110 -80 -50 -20 10

Phase HWR 1 (deg)

sig

ma

(k

eV

)

simulations

RBS

Energy spectra were monitored as a function of phase of an individual HWR while the rest downstream HWRs are detuned. As a result the synchronous phase and resonator voltage can be calibrated. The beam energy obtained from RS is compared with TOF results and TRACK simulation. L.Weissman et al. DIPAC 2009

The RS measurements provide information on the beam energy spread and low-energy background. The experimental results are compared with TRACK simulation. The intrinsic energy resolution and effects of scattering on the gold foil were not taken in account in the simulation of the beam energy spread.


Calibrating cavity #6

2.6

2.7

2.8

2.9

3

3.1

3.2

-60 -30 0 30 60 90 120 150 180 210

Ene

rgy[

MeV

]

Phase HWR6 (deg)

3.1

3.2

3.3

3.4

3.5

3.6

3.7

3.8

100 200 300 400 500 600 700 800 900 1000

En

erg

y )M

eV

(

HWR )kV(

1 the saraf accelerator commissioning dan berkovits on behalf of saraf team soreq nrc seminar @ fnal...

Documents

tup74 slide

tail slide

molecular breakup slide

psm beam dump target

y deuterons x y

ma deuterons

saraf phase

piel epac