Injector Cyclotron for a Medical FFAG

H- compact AIMA cyclotron

concept Design Results

M. Conjat, J. Mandrillon,

P. Mandrillon, J. Pasternak

Tentative Layout (according to J.Pasternak)

AIMA cyclotron (1.75 m diameter)

Septum 0.7 T

6 quads in straights

Preliminary geometry of injection line into RACCAM FFAG

conceptDesign Results

conceptDesign Results

Concepts….Design Choices

Variable energy-extraction from 7 to 15 MeV Suitable: 1 energy step corresponds to a 1cm depth step in tissues.

Fast accelerationParticles reach 15 MeV in 60 turns, well separated.

Simple design H- acceleration Multi strippers extraction system with fast switches.

High energy gain per turn Power is pulsed in order to get a 50 kV peak to peak acceleration voltage,

with 6 gaps/turn.

A single cavity 3 dees galvanically connected, working on the 3rd Harmonic

External High Brightness H- MultiCusp Ion Source10 mA/cm², 5mA dc (to accelerate 350A)

TYPE OF CYCLOTRON: Negative ion

Size 1.75 diameter

Weight 13 tons

Ion source: H- MultiCusp, external

Extracted Current density (dc) 10 mA/cm²

MAGNET: Closed geometry, 3 sectors

Average field 1.55 tesla

Pole radius 38 cm

Amp turns 52580

RF SYSTEM: 1 single cavity

Number of dees 3

RF voltage 50 kV

RF frequency 70.6 MHz

RF power ~2 kW, pulsed (dc: 2%)

Resultsconcept

DesignMain Characteristics

high brightness multicusp ion source

AIMA cyclotron for FDG Production

Extracted beam intensity requirements

Maximum Dose Rate 5 Gray/min

FFAG (100 Hz rep. rate) 2.5 108 proton/cycle,

3 109 proton/cycle needed at injection

With multiturns injection (10t):

3 108 proton/ turn needed at injection

10 turns to fill the FFAG 3 s (injection F: 3 MHz, 10 revolution time)

With the Cyclotron at 70.6 /3rd Harm:

~200 cyclotron bunches

Cyclotron: ~1.5 107 proton/bunch

Cyclotron DC Current equivalent

170 A

Requirement at FFAG injection: Energy Dispersion < 50 keV Cyclotron DC Current goal:350 A

Resultsconcept

Design

About the magnet design

r

r & z versus Radius with ‘EUQUIL’

z

3D calculation CST, Compared with measures

B-field Isochronisms versus Radius with ‘EUQUIL’

Resultsconcept

Design

About the Dynamic design

3D electrostatic calculation& Central region optimization with ‘AGORA’

Energy gain in gaps optimization to accelerate fast.

Median plane acceleration

Trajectories

& Centers of Curvature

Resultsconcept

Design

R (cm)

Energy Gain in gap 6:

90 %

conceptconcept Design

Results

Multiple strippers to find a Cyclotron Energy

FocusVariable Energy ~7 to ~15 MeV

Variable energy extraction

Strippers

Energy Focus

conceptconcept Design

Results

Extraction Energy - 14 Mev

Horizontal Envelop (1 ) mm mrad

Vertical Envelop (1 ) mm mrad

Energy spread 75% < 50 KeV

Normalized Transversal Emittances:

0.5 mm mrad vertical (worst case)

0.3 mm mrad horizontal

+ multiple scattering due to stripper traversal

Bunch length in 1st gap: 15°

4 mm

1 mrad

20 mrad

15 mm

Tracking at Extraction

Envelop at Focus

conceptconcept Design

Results

Extraction Energy - 11 Mev

Horizontal Envelop (1 ) mm mrad

Vertical Envelop (1 ) mm mrad

Energy spread 81% < 50 KeV

Normalized Transversal Emittances:

0.5 mm mrad vertical (worst case)

0.3 mm mrad horizontal

+ multiple scattering due to stripper traversal

Bunch length in 1st gap: 15°

4 mm

0.6 mrad

30 mrad

20 mm

Tracking at Extraction

Envelop at Focus

conceptconcept Design

Results

Extraction Energy - 8 Mev

Horizontal Envelop (1 ) mm mrad

Vertical Envelop (1 ) mm mrad

Energy spread 91% < 50 KeV

Normalized Transversal Emittances:

0.5 mm mrad vertical (worst case)

0.3 mm mrad horizontal

+ multiple scattering due to stripper traversal

Bunch length in 1st gap: 15°

Tracking at Extraction

Envelop at Focus

4 mm

0.4 mrad

40 mrad

30 mm

Thank you for your attention

concept Design Results