The Injector Design C.Y. Tan 01 Sep 2011 1 The Injector BNL - - PowerPoint PPT Presentation

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The Injector Design C.Y. Tan 01 Sep 2011 1 The Injector BNL - - PowerPoint PPT Presentation

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The Injector Design C.Y. Tan 01 Sep 2011 1 The Injector BNL (2009 line) FNAL Proposed 1 x 35 keV H- source (round 2 x 35 keV H- sources (round type) type) on a slide LEBT (~ 4 m) For redundancy Short LEBT (~118 cm)

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SLIDE 1

1

The Injector Design

C.Y. Tan 01 Sep 2011

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SLIDE 2

2

The Injector

  • 2 x 35 keV H- sources (round

type) on a slide

  • For redundancy
  • Short LEBT (~118 cm)
  • 2 solenoids for focusing
  • Xe gas for neutralization
  • Einzel lens chopper
  • RFQ 201.25 MHz, 1.2 m long
  • Short MEBT (1 m)
  • 2 sets of doublets
  • 1 BNL style buncher
  • 1 x 35 keV H- source (round

type)

  • LEBT (~ 4 m)
  • 2 x solenoids
  • Xe gas for neutralization
  • 1 Einzel lens
  • 1 electrostatic chopper.
  • RFQ 201.25 MHz, 1.5 m long
  • Short MEBT (0.73 m)
  • 1 set of triplets
  • 1 buncher

FNAL Proposed BNL (2009 line)

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SLIDE 3

3

H- Source

  • BNL style round (dimpled) magnetron source.
  • More discussion in D. Bollinger's talk.
  • BNL has very good experience with this type of
  • sources. Very reliable.
  • FNAL has a lot of experience with slit type

magnetron sources. Easier transition to round type.

  • Good choice because it can use the same type of

hardware FNAL already has.

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SLIDE 4

4

LEBT

46.55”

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SLIDE 5

5

LEBT (cont'd)

  • BNL source emit-

tance numbers

  • RFQ input numbers

from manufacturer

  • Assume beam is

neutralized.

Edge of beam pipe

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SLIDE 6

6

Solenoid Settings in Trace2D

Focal length is consistent with as built solenoid set to 500 A.

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SLIDE 7

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FNAL Solenoids

Solenoids run DC. Water cooled. Settings probably > 500A. Designed by A. Makarov and V. Kashikhin.

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8

B field Measurements

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9

Small x-offset (~ 0.2 mm) in position and angle when current is changed from 500 A to 600 A. Do not expect to work below 500A. No change in y. Should be correctable with dipole correctors.

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10

Neutralization using N2 in test stand

N2 used. Good vacuum 1e-6 torr. Bad vacuum 1e-4 torr. Note: pressure gauge quite far from beam in test stand. Faraday cup measurement

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11

Chopper

  • Einzel lens is used as a chopper
  • Suggested by D. Raparia
  • Lens placed close to the entrance of the RFQ

– Keep de-neutralization region to a minimum. – Beam is already tightly focused by the solenoid at this

  • location. So neutralization is probably at a minimum here.
  • Einzel lens as chopper experiments in the test

stand have verified that method works.

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12

Einzel Lens Chopper

  • Simulation using SIMION
  • Optimized lens
  • 2” long
  • 1.75” diameter
  • -37 kV to stop 35keV

beam.

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SLIDE 13

13

Einzel Lens as Built

Designed by A. Makarov

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SLIDE 14

14

Chopper Timings

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SLIDE 15

15

Einzel Lens Test

Note there is scraping at the beginning of the pulse in the test stand. This is a different Einzel lens than the one that we will be using. This Einzel lens is 2” in diameter and 2.5” long. Note: injector lens is 1.75” diameter and 2” long.

  • F. Cup

Toroid

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16

Einzel Lens Test (cont'd)

Rise time on Faraday cup is bet- ter than 50ns. Con- sistent with thyrat- ron turn on of 35 ns. Ringing from finite bw of Faraday cup.

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17

LEBT Corrector Dipoles

Designed to fit over 4” beam pipe. Corrects drop in integrated Bdl when placed close to iron. 10A corrects 1 deg. H+V in one < 1.5” package.

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18

RFQ

Designed by A. Schempp. Tuned by J. Schmidt and B. Koubek. Rod type RFQ.

>

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SLIDE 19

19

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SLIDE 20

20

As found RFQ parameters. Note frequency is 190 kHz too low.To be cor- rected with tuner.

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21

PARMTEQM Simulations

Transmission effi- ciency > 99% for 60mA beam.

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SLIDE 22

22

PARMTEQM Simulations (cont'd)

Input Output

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SLIDE 23

23

MEBT

Doublet – Buncher – Doublet (30 cm longer compared to BNL MEBT)

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24

MEBT Simulations

PARMILA shows 95.1% of the beam is captured at the end

  • f DTL 1.

Note: Lattice of DTL not well understood! Using “as found” DTL lattice from M. Popovic. Note: Quads are very strong

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SLIDE 25

25

Before doublet After Buncher Before Tank 1 End of Tank 1

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26

Buncher

Same as BNL (except FNAL buncher is made of copper while BNL buncher is made of aluminium) Designed by M. Okamura. Must have grids to get transit time factor correct. Low power test without grids are complete at FNAL. With grid has been done in Japan.

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SLIDE 27

27

Grids

Grids to correct transit time factor. Picture is BNL grids.

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Bead Pull Data

FNAL Japan Full width half height ~ 30mm gap. With grid effectively re- duces gap or increases transit time by 40%

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Doublets (Quads with embedded corrector dipoles)

Quadrupole runs DC and water cooled. Iron core. Has embedded corrector dipoles. Overall length of doublet is 7”, 1.5” beam pipe.

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30

Quadrupole Design

Single quad. 4.4 kA/pole Doublet 4.4 kA/pole 400A and 11 turns per pole Field inhomogeneity is 1.7% @ 1 cm with F/D at 4.4kA/pole.

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31

Sextupole Component from Dipole

Integrated vertical dipole field at centre And 1 cm

The dipole contributes a sextupole component

  • f Sint=0.56410-4 Tm when powered to de-

flected beam 0.2 deg. (gives 1mm deflection from last corrector to the DTL, Bdl = 0.4510-3 Tm) If integrated sextupole field A3 < 0.5% of integ- rated quadrupole field, transverse emittance blow up < 1%.

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32

Coupling

If quad random rolls < |0.5| deg for all 4 quadrupoles, emittance growth is < 1% at the start of DTL 1.

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33

Performance Goals

At minimum, must perform as well as present system.

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Conclusion

  • Nothing in the design is technically

unachievable.

  • Not pushing any envelopes!
  • However, there are some concerns. See

“Outstanding Issues and Contingencies Talk”

  • Copying as much as possible BNL design has

helped the injector design.

  • There will be a lot of work to validate design in

the test set up.

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35

Acknowledgements

  • D. Raparia, J. Alessi, M. Okamura (BNL)
  • Generous hosts when we visited.
  • Shared drawings of solenoid and quadrupoles.
  • Allowed us to copy BNL buncher (Okamura)

– Fixes to BNL buncher that were incorporated into FNAL buncher.

  • Discussions with D. Raparia

– Supplied initial input files to Trace, Parmila and Parmteqm.

  • A. Makarov, V. Kashikhin, G. Velev (FNAL, TD)
  • Designed and built solenoids, einzel lens and quads.
  • All the personnel in Proton source, Mech. Support, EE Support.
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36

Backup Slides

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37

Test Stand

Einzel lens is 2” in diameter and 2.5” long. Note: injector lens is 1.75” diameter and 2” long.

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