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CYCLOTRONS FOR ADS
P.Mandrillon, J.Mandrillon, M.Conjat
AIMA DEVELOPPEMENT SA
ThEC13,CERN,Geneva, October 30 2013
- The PSI outstanding Cyclotron story
- Two examples of High power cyclotron drivers
- A new single stage cyclotron design
- Conclusions
OVERVIEW
1966: SIN early Design – Feb. 1974:1st 100 mA beam
The 72 MeV Philips injector
The 590 MeV Ring Cyclotron
1984: Towards Higher intensity
The new separate sectors Injector
Old injector
72 MeV
590 MeV
The PSI Layout
PSI: For H+ High extraction Efficiency is needed
> Increasing the separation d between turns
d=R/N*(g/(g+1))/nr2
> Reducing the number of turns N with
High power new RF copper cavities.
PSI: Main difficulties for higher intensities
The 2 stages geometry is fixed: a 72 MeV Injector for the 590 MeV
Booster ring.
Difficult Points: the various injection and extraction channels
Beam « distortions » on the long (70m) transport line
1995: The early cyclotron proposal for driving
the Energy Amplifier with a 1 GeV 3 stages Cyclotron
H-
H+ 12 sectors- 6 Monogap cavities- 2FT cavities
4 sectors-2 delta cavities
1 Flat-top cavity
The TRADE Cyclotron Driver: Stripping Extraction of
240 MeV-H2+ Providing 3mA-120 MeV Proton Beam
60 KeV injection Line: AIMA H2+ ion
source (50 mA/cm2) + LEBT
+ axial injection with spiral inflector.
TRADE CYCLOTRON: MEDIAN PLANE VIEW
AND PRINCIPLE OF H2+ EXTRACTION
Max Energy (H2+/P) 240/120 MeV
Nominal Extr. Intensity 3 mA proton (1.5 mA H2+)
External diameter 4.4 m
# of spiral sectors 4
Current density in SC coil 44 A/mm2
Radiofrequency 70.4 MHz
#/type of RF cavities 4/delta-2 gaps
Peak Voltage (Inj/Extr) 70/200 KVolts
RF Power Losses 280 KWatt
Stripper H2+
H+
Texas A&M University
• Two Stages Cyclotron: 100
MeV SF injector + 800 MeV SF
booster.
• Stack of 3 Cyclotrons in //
• Booster: 12 Flux coupled
stack of dipole magnet
sectors
• 10 Superconducting 100 MHz
RF cavities providing a 20
MeV Energy Gain/turn
• Large turn separation
allowing to insert SF beam
transport channels made of
Panofsky Qpoles (G=6T/m)
TEXAS A&M: 800 MeV SUPERCONDUCTING
STRONG-FOCUSING CYCLOTRON
The DEAdALUS Project:
3 High Power 800 MeV-2 mA Cyclotron Complex
For Neutrino Experiments in the USA
Cf. Roger Barlow Presentation in this session
XXXVIII ECPM, 9-12 May, PSI - Zurich 4
Superconducting Ring Cyclotron
<1 mA> H2+ 800 MeV/n,
<1.6 MW>, Peak power 8 MW
Injector Cyclotron
< 1 mA> H2+ 60 MeV/n
<120 kW>, peak power 600 kW
Stripper foils
Extraction 1
Extraction 2
The DEAdALUS Project
800 MeV-2 mA High Power Cyclotron Complex:
3 Cyclotron Complex for Neutrino Oscillations Experiments
An innovative conceptual design for a cost
effective, compact and reliable ADS driver
The reverse valley B-field
separate sector Ring
Cyclotron (patent pending)
The reverse valley bends Cyclotron
Achieving isochronism while keeping
vertical focusing at high energies is
challenging: isochronism implies a large
+ve radial gradient of the average B-field
resulting in a strong vertical defocusing:
Dnz2 = -(g2-1) = - (d<B>/dr)r/<B>
which could be overcome by edge and
spiral focusing(cf. PSI Ring Cyclotron)
nz2 =-(g2-1)+F2(1+2 tan2z)
F2= Field Flutter = (<B2>-<B>2)/<B>2
z= spiral angle of the sector
A simpler Separate sector Cyclotron:
=> No spiral => Stronger Flutter
= Reverse valley B-field
Proton extraction through stripping of H2+ is simple !
Triple injection central region
40° of phase acceptance
A major advantage: The B-field configuration in the central
Region allows acceleration at low energies
An injector cyclotron is not needed anymore !
Central region for H2+ multi-injection
60 KVolts injection HV
Axial injection Line
Electrostatic spiral inflector E=18KV/cm
> Superconducting Coils . Rmin: 4.2m Rmax: 7.1m
.Total length ~50m
.Section: 160 mm * 310mm
.Current density 55 A/mm²
> 6 straight hill sectors (14 tons)
> 12 small valley sectors
Return yokes could be added to reduce the coil stored
energy ( 3 times lower than in a classical booster!)
Magnetic field layout of the 1600 MeV H2+ design
RF cavities H=6 / 36.3MHz
• 6 cavities inserted in the valleys
(12 accelerations gaps / turn)
• Pumping through the stem
1600 MeV H2+ layout
• 150 kV in the center up
to 450 kV at extraction
• Q = 6200 ->Total losses
3MW
RF-delta double gap cavities
Peak Voltage versus radius
Vertical cross-section through the valley axis
Initial condition:
5mm vertical amplitude @ 155MeV
New extraction concept for H2+ stripping:
short trajectory, no focusing elements, no complexity
Extraction
Simulation of H2+ acceleration up to 1600 MeV
The reverse valley B-field concept avoids the internal loop
(cf. DAEdALUS extraction) for the stripped proton beam from H2+.
Different extraction concepts of 800 MeV protons
Easier extraction of separated turns in the reverse valley field
No septum, only passive channel with
bars either side of the median plane
Possibility to house a very efficient
radiation protection in graphite
Acceleration and extraction of 800 MeV protons
Dr for the 3 last turns with 5MeV energy gain / turn
Energy (MeV)
CONCLUSIONS
A single stage 800 MeV Reverse Valley Field Cyclotron:
a good candidate for an industrial ADS demonstrator
ADVANTAGES
• Single stage accelerator
– Low construction budget and Low operational cost
– Less components than traditional solutions high reliability
– No transport / matching issues between stages
– Compact system (lower cost for the building)
– Stored energy at least 3x smaller than in conventional 2 stages superconducting
booster
• 3 sources + axial injection lines
– redundancy
– reliability
– Intensity Flexibility:
• 8 mA protons>4mA H2+ => 2 Ion sources on + 1 Ion source in Stand-by
• 12 mA protons>6mA H2+ => 3 Ion sources on
• Simplified Extraction system : No Septa required
– Increasing reliability
– less activation => easier maintenance