Proton Driver b1 R

1
Proton Driver blt1 RD

• Giorgio Apollinari
• April 10th - 12th , 2005

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Outline

• Ion Source
• Radio Frequency Quadrupole (RFQ)
• Medium Energy Beam Transport MEBT
• Room Temperature Resonators section
• Superconducting spoke resonators sections
• Single Spoke, Double Spoke (and Triple Spoke)
  resonators
• Squeezed Elliptical Superconducting Cavities
• b(0.47, 0.62) 0.81 resonators
• Conclusions

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Goal of the System

• Increase H- energy from E0 MeV to E1200 MeV.
• Multiple geometrical bs 0.21, 0.4, ( 0.47, 0.61
  for elliptical cavities or 0.61 for spoke
  cavities) and 0.81

Cavity Accelerating Gradient
(Elliptical Cavity Option for Beta0.47 and 0.61)
Epeak 52 MV/m, Phi_Synch -30 to -15 degrees
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Accelerating
Beta 1.00
Gradient Eacc
Beta 0.81
25
Eacc TTFCos(f)
Beta
0.61
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Gradient (MeV/m)
Beta
0.47
15
10
5
0
1
51
101
151
201
251
301
351
Elliptical Cavity Number
4
Front end general layout

• Ion source H-, LEBT 0.065 MeV
• Radio Frequency Quadrupole 4-5 m, 3 MeV
• MEBT (2 bunchers, 4 SC sol., chopper) 4 m
• RT TSR section (21 resonators, 21 SC solenoid)
  10 m 15.2 Mev
• SSR section (16 resonators, 16 SC solenoids)
  12.5 m 33.5 MeV
• DSR section (28 resonators, 14 SC
  solenoids) 17 m 108 MeV
• TSR section (42 resonators, 42 quads) 64
  m 408 MeV

Frequency 325 MHz Total length 112 m
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Ion source

• The ion source is a multicusp, rf-driven, cesium
  enhanced source of H-.
• Output energy 65 keV, output peak current 12.7
  (38) mA, pulse length 3.0 (1.0) ms, pulse rate
  2.5(10) Hz

• Design concept - SNS,DESY
• Design issues in general these
• sources are well understood.
• SNS ion source can be used for
• PD. Longer RF antenna lifetime
• desirable.

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Toward Selecting an H- Ion Source

• Beam tests on the SNS RF H- ion source (Doug
  Moehs)
• 3.1 ms long pulse, 11.5 mA average, at 5 Hz
• The SNS routinely runs 1 ms long pulses, 30 mA at
  60 Hz

The SNS Ion Source Test Bench and LEBT

• Jumpstart with H source with 100 kV 10 mA PS
  and 50 keV output

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RFQ

• RFQ accelerates H- from 0.065 to 3 MeV , Ip up
  to 28 mA
• Now RFQs are standard devices for proton
  machines. There are good designs (J-PARC, SNS)
  available.

• Our additional requirement for RFQ beam dynamics
  design is an axisymmetric output beam to reduce
  halo formation in MEBT and RT SR section.
  (P.Ostroumovs proposal).

J-PARC 30 mA RFQ
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RFQ

• For the RFQ mechanical design the main issues
  are
• Machining of large parts with high accuracy ( 25
  microns for vane tips)
• Assembly the RFQ body. Brazing (SNS approach),
  though clamping or laser welding with ring
  contacts works well too (J-PARC).
• Currently basic RFQ parameters are found. RF
  design and mechanical design are planned to be
  done by ANL-FNAL collaboration.

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RFQ

• or AccSys !

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MEBT

• MEBT has three main functions
• matching the beam from the RFQ exit plane into
  the MEBT chopper plane
• cleanup chopping
• matching the remaining particles into the RT TSR
  section ( beam diagnostic)

CERN-SPL System Deflecting structure
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MEBT

• In our MEBT we have an axisymmetric beam after
  RFQ.
• 4 SC solenoids are used for focusing and matching
• 2 RT TSR are used as the rebunchers
• One chopper
• This is conceptual design. The detailed design is
  still ahead.

SC solenoid
MEBT
RT SR
TRACK simulation
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MEBT

• The MEBT installed at KEK.

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MEBT SC Solenoids

• First Prototype be Oct. 05

Stresses at 0 A, 4K
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RT SR section

• Why this room temperature section?
• Beam dynamics at low beta demands adiabatic
  acceleration, smooth transition from RFQ to SC
  sections which have high accelerating rate.
• That means
• - variable beta accelerating lattice - gaps
  and distances between them change with particle
  velocity
• - focusing period should be as short as
  possible
• - smooth increasing of accelerating rate
• It is expensive and difficult to design and
  produce beta variable SC cavities. This is not a
  problem for RT cavities

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RT SR section

• Our solution is Room Temperature Spoke Resonator
  (aka Cross-bar H-type resonators) section from 3
  MeV to 15 MeV .

Solenoid in individual cryostat
Shape Optimization
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RT TSR section

• The main advantage of RT SR is its high shunt
  impedance.

• For 3-15 MeV losses in copper
• DTL 1.06 MW
• RT SR 0.4 MW
• Diameter of resonator
• DTL, SDTL 70 cm
• RT SR 40 cm
• RT SR expected to be cheaper

RT TSR
SDTL (J-PARC)
DTL (J-PARC)
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RT SR section
There no prototypes of RT SR and SC solenoids
that meet our requirements , but we can find
similar efforts elsewhere
Cold model of CH resonator (Frankfurt).
SC quadrupole lens in individual cryostat
(Berkley)
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SC Spoke Resonator

• SC Spoke Resonator sections provide acceleration
  from 15 MeV up to 400 MeV.
• RD work to study and optimize all three types of
  resonators

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SC Spoke Resonator

• Spoke Cavities and CryoModules
• Why Spokes
• Fewer types higher operating T (4 K)
• Simulation shows that improved beam quality can
  be expected (increased
• longitudinal acceptance)
• Superior mechanical stability for blt0.6
• Decade-old technology (Delayen et al., LINAC 92)
• Open to Elliptical cavities processing conditions
• HPR
• Ultra-clean processing

Argonne, Spring 2001
Q
Argonne Result b0.4 cavity
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SC Spoke Resonator
Shepard, Kelly, Fuerst, presented at PAC 2003,
SRF 2003
The cavity can operate cw at gradients up to 12
MV/m, producing more than 4.5 MV of accelerating
potential
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SC Spoke Resonator
ß0.5 and 0.64 triple-spokes (RIA)

• RD at FNAL/ANL to study and optimize all three
  kinds of resonators

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SC Spoke Resonator RD

• Shape Optimization design Collaboration with ANL

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SC Spoke Resonator RD
Total Deformation at 2 atm.
Total Deformation at 2 atm.
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SC Spoke Resonator Cryomodules
b0.21 16 Cavities/Cryomodule 1 Cryomodule 16
focusing Solenoids/Cryomodule
b0.4 14 Cavities/Cryomodule 2 Cryomodules 7
focusing Solenoids/Cryomodule
Open Technical Choice
b0.61 6 Cavities/Cryomodule 7 Cryomodules 6
focusing quads/Cryomodule
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Technical Solutions
Positive Ion Injector Cryomodule

• Separate Vacuum
• Efficient, top loading
• Good alignment capability

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ANL/RIA Cryomodule Design
Clean Assembly suspended from Top Plate
Clean Room String Assembly
Assembly lowered in vacuum vessel
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Technical Solutions

• FNAL idea for Spoke Cavities Cryostat

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ANL-FNAL Test Cryostat

• Common approach for PD/RIA test cryostat

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Elliptical b (0.47, 0.61) 0.81

• Cryostat based on TESLA design
• 8 cavities, operating at 2K
• Focusing cold quads
• 9 quads in b0.47 (40 T/m)
• 5 quads in b0.61 (33 T/m)
• 3 quads in b0.81 (5 T/m)
• 1 quad in b1 (3 T/m)
• Expected Heat Loads
• 5 W in 2 K
• 20 W in 4.5 K
• 200 W in 50 K

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Elliptical b (0.47, 0.61) 0.81
b0.47 8 Cavities, 6 cells/cavity 9 focusing quads
Open Technical Choice
b0.61 8 Cavities, 6 cells/cavity 5 focusing quads
b0.81 8 Cavities, 8 cells/cavity 3 focusing quads
b1.0 8 Cavities, 9 cells/cavity 1 focusing quad
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Elliptical b (0.47, 0.61) 0.81

• Build on FNAL/SNS/JLAB/MSU experience and
  collaboration to develop blt1 cavities.

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CONCLUSIONS

• blt1 RD activities started
• Focus on
• Ion source (H) in SMTF by June
• Addressed design/development of SS cavities at
  325 MHz
• Converge on procurement of first Spoke Cavities
  by FNAL
• Starting RFQ prototyping and development
• To do
• Warm Temperature Spoke Resonators
• Focusing Magnets (Solenoids and Quadrupoles)
• Well defined plan to address key issues for PD
  RD.