part iii commissioning. proof of principle ffag (pop) study the world first proton ffag...

Part III

Commissioning

Proof of Principle FFAG (POP) study

• The world first proton FFAG– Commissioned in March 2000.– From 50 keV to 500 keV in 1ms.– Proof of proton FFAG– Various beam operations

Components

POP synchrotron

• overview

Optics with linear approximation

• SAD calculation

Multi-turn injection

1 turn (left) and 5 turns (right)

Beam acceleration

• BPM signal

Observations of machine parameters

• Tune survey

• (dynamic) aperture survey

Tune at injection with various F/D ratio

Energy dependence

Synchrotron oscillation frequency radius position

Dynamic aperture surveysingle particle simulation

Experimental results

Center of gravitymulti-particle simulation

Amplitude dependent tune shift

More beam manipulation study

• Multi bunch acceleration• Acceleration with 2 fixed frequency• Slow extraction with massless septum• Resonance crossing

Multi bunch acceleration

• As long as two buckets are separated in longitudinal phase space, simultaneous acceleration is possible.

• Repetition rate is effectively increased.

RF pattern

• Second RF follow the first one.

Acceleration with two RF buckets

• Experimental results

Acceleration with 2 fixed frequency

• Idea is to accelerate a beam with two (or more) fixed frequency.

• By simulation, if the

timing of two RF is

chosen correctly,

a part of a beam is

accelerated.

Experimental results

Black: simulation with two buckets.Green: simulation with one bucket.Red: experiment with two buckets.

It is proven experimentally thatenergy is increased more than thatcan be accelerated with one bucket.

Slow extraction with massless septum

• Septum without septum blade.• Field does not drop off shapely, rather linear decay like a quadru

pole.

Field distribution (calculated and measured)

• Measured a model magnet.

How the massless septum works.

(a) Kick by massless septum.(b) Cut by electric septum.(c) Restore the beam by massless septum.

Resonance crossing

• Crossing speed is a parameter

Signal at 4 RF patterns

• 20 deg. 10 deg.

4 deg. 2deg.

•Red arrow indicates time when a beam hits chamber.•When the ramping is slow, a beam is lost before hitting chamber.