HINS ProtonSource/LEBT Beam Measurement

Meeting on HINS Beam Dynamics and Diagnostics

March 13, 2009

Salah Chaurize

Vic Scarpine

Wai-Ming Tam

Content

• Layout of HINS proton source/LEBT

• Beam profile measurement using wire scanner

• Steering capability of the trim dipole magnets

• Beam rotation by focusing solenoid

Pictures of LEBT and Wire Scanner

Proton Source Solenoid Wire

Scanner

Beam Energy = 48 keV

Beam Current = 8 mA

Name Range [Amp] [Gauss]

US Upstream Solenoid 410 – 490 3800 – 4600

DS Download Solenoid 450 – 570 4200 – 5300

UH Upstream Horizontal Trim 0 – 3 0 – 100

UV Upstream Vertical Trim 0 – 3 0 – 100

DH Downstream Horizontal Trim 0 – 3 0 – 100

DV Downstream Vertical Trim 0 – 3 0 – 100

Layout of LEBT

Wire Scanner

US DSUH, UV DH, DV

Proton

17 cm

52 cm 22.4 cm

17 cm

kpipexagxag ),,(),,( 02220111

backgroundconstant k

16.5cm radius pipe

)(1

2

)(exp),,(

22

2

20

0

r

xrr

pipe

xxaxag

Expression used for fitting:

where

A Typical Fit

Proton Other species

A Typical Wire Scan

For a typical fit, standard deviation for is about 2%.

Beam Pipe

Other species fill out the whole beam pipe.

Horizontal Beam Width

The strength of the upstream solenoid has little effect on beam size.

The size of the beam waist is measured to be ~0.7 mm.

Vertical Beam Width

The strength of the upstream solenoid has little effect on beam size.

The size of the beam waist is measured to be ~0.6 mm.

Asymmetric Beam

The beam is asymmetric.

Beam asymmetry can be due to misalignment in beamline and/or possibly from the proton source itself.

Comparison to TRACK Simulation

Input Beam for TRACK:

ε(n,rms) = 0.233 πmm-mrad

α = -1.82

β = 0.331 mm/mrad

US = 380 Amps

Current = 8 mAEnergy = 50 keV

Wire Scanner

West

Up

EastDown

Trim Dipole Steering

Trim dipoles at 100 Gauss.

All possible combinations of trim setting fall inside the diamond.

18 mm

18 mm

55o

Steering effect is rotated by the downstream solenoid.

Beam Rotation by Solenoid

Azimuthal Kick

Paper by K.T. McDonald

Solenoid

Azimuthal Kick

mc

LeB

p

eBL

effm

h

2

1

2

12

1

Angle of rotation thru solenoid

Leff

x̂

Center of Solenoid

Azimuthal Kick

Helical Path

Uniform Field

Beam Rotation by Solenoid

DS = 450 to 570 Amps

Exact location of beam needed to be analyzed.

Rotation of beam as a function of solenoid field matches well with calculations.

mc

LeB

p

eBL effm

h

2

1

2

1

2

1

Conclusion

• Beam waist at wire scanner rms ~ 0.7 mm

• Beam is asymmetric. It can possibly be due to misalignment.

• Trim dipoles steer beam +/- 9 mm both planes.

• Beam rotation due to solenoid agrees with model. Model can possibly be used to determine solenoid misalignment.

8.1 cm

Vanes of RFQ

Wire Scanner

14 cm

Downstream Solenoid

5.9 cm

Distance Between WS and RFQ

There is a known distance between the wire scanner and the vanes of the RFQ.

US = 440 amp

DS = 510 amp

Uni-Polar Steering Dipole

DV (Down)

DH (East)

UV (Up)

UH (West)

DV

DH

UVUH

UH

UV

DV

DH

Symmetric

Uni-Polar Steering Dipole

Downstream trims give more steering.

DS = 450 to 570 Amps

US = 410 to 490 Amps

Vertical Beam Width