Beam steering capability for target position uncertainty

Simon Yu & Enrique HenestrozaLawrence Berkeley National Laboratory

ARIES MeetingOctober 3, 2002

PPPL

Steering in Heavy Ion Drivers

3 kinds of steering in drivers:1. Slow (or DC)-dipoles - centroid correction

(shot-to-shot reproducible errors)2. Fast Correctors (µs to tens of ns)

- head to tail variations(shot-to-shot reproducible errors)

3. Pulsed correctors (~ms)(shot-to-shot variable errors)

Steering Capability for Target Position Uncertainty belongs to the 3rd class.

Requirements:

- Respond in 25ms (target injection at 200m/s)

- Correction of a few mm (< ± 2mm)

Sample dipole corrector layout for final focus

First Beam through NTX Magnetic Transport (August 2002)

NTX with source tank, 4 pulsed quadrupoles,and diagnostic tankIn Bldg. 58, LBNL

Profile at magnet exitCurrent at magnet exit

voltage5cmcurrent

Test Stand for Measurement of Transient Magnetic Field

Three-way B probes•

(Bx, By and Bz )

0

1

2

3

4

5

6

7

0.5 1 1.5 2 2.5 3 3.5

Time (ms)

Cu

rren

t (kA

)

0

0.5

1

1.5

2

2.5

3

B (

kG

)

Current (kA) #1 Br (kG) #2 -Br (kG) #3 Br (kG) #4 -Br (kG)Probe #1 R

-1

-0.5

0

0.5

1

1.5

0.5 1 1.5 2 2.5 3 3.5

Time (ms)

Sco

pe (

V)

#1 Br (kG)

0

0.5

1

1.5

2

2.5

3

0.5 1 1.5 2 2.5 3 3.5

Time (ms)

Br

(kG

)

•B(t)

B(t)

Overlay of B(t) in 4 quadrants and I(t)

Axial profile (measurement vs. ANSYS)

First Beam through Neutralized Drift Section with Plasma Plug

Spot size with plasma

Magnetic section

Spot size without plasma

Pulsed arc plasma source

Drift tube Scintillating glass

Dipole corrector Requirements are very easy to meet

Required:

Pulsed dipoles ~ 1kG in < 25msec

Achieved:

NTX quadrupoles ~ 7kG in 1 msec