Perspectives for an energy increase
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Perspectives for an energy increase of MAMI C. Andreas Jankowiak Institut für Kernphysik Johannes Gutenberg – Universität Mainz. 23.09.2008 Cristal Ball @ MAMI Collaboration Meeting. Present situation. MAMI B. 855.3MeV, s E =0.013MeV (0.001%) (883.1MeV maximum)

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Perspectives for an energy increase of MAMI C

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Perspectives for an energy increase of mami c

Perspectives for an energy increase

of MAMI C

Andreas Jankowiak

Institut für Kernphysik

Johannes Gutenberg – Universität Mainz

23.09.2008

Cristal Ball @ MAMI

Collaboration Meeting


Perspectives for an energy increase of mami c

Present situation

MAMI B

  • 855.3MeV, sE=0.013MeV (0.001%)

  • (883.1MeV maximum)

  • max. 103mA cw current

  • eh=8 nm rad, ev=0.5 nm rad

  • (allows for beam foci of ~mm)

  • Halo: < 10-5 at r > 5∙sr


Perspectives for an energy increase of mami c

Present situation

MAMI C

  • 1508.4MeV, sE=0.100MeV (0.007%)

  • max. 100mA cw current (successful tested)

  • eh=12 nm rad, ev=2 nm rad

  • (measured, ev definitely overestimated)


Perspectives for an energy increase of mami c

What defines the end energy of an RTM:

Eout=EInj+z•DE

d

magnet distance

2•R

i+1

i

1

EInj (b1)

DE

dynamic coherence-condition:

static coherence-condition:

k,n: integer numbers


Perspectives for an energy increase of mami c

Increasing the end energy of an RTM:

  • increase B and adjust DE to full fill dynamic condition

  • adjust Einj to full fill static condition

Energy increase by factor d means:


Perspectives for an energy increase of mami c

What defines the end energy of a DSM

Einj

dynamic coherence-condition:

static coherence-condition:

k,n=1: integer numbers

Energy increase by factor d means (as for RTM):


Perspectives for an energy increase of mami c

18

1600

16

1400

14

1200

12

10

1000

8

800

0

10

20

30

40

6

0

5

10

15

20

25

30

35

40

What defines the end energy of a HDSM

In reality our machine (Harmonic Double Sided Microtron) is

“a little bit more complicated”

but the scaling is the same !

beam energy

Energy gain per turn

Eout=(1508.4±0.4) MeV

total

Bmax=1.539T

linac I (4.90GHz)

linac II (2.45GHz)

Einj=855.11MeV

Energy increase by factor d means (as for RTM):


Perspectives for an energy increase of mami c

Energy of the HDSM

Therefore:

Changing the maximum energy by factor d

implies scaling of all machines by factor d (E and B fields)

The maximum energy of RTM3 used

so far is: 883.1MeV !

Ein=855.12MeV

Scaling the HDSM by 883.1/855.3 (+3.25%)

results in 1557.4MeV beam energy

of the HDSM.

Eout=

855.30MeV

Ein

Eout=180.03MeV

Eout=1508.4MeV

Ein

Eout=14.86MeV

Ein=3.97MeV


Perspectives for an energy increase of mami c

focussing

defocusing

Increasing the magnetic field of the HDSM dipoles

remember: dipoles incorporates field gradient perpendicular

to the pole face to compensate vertical defocusing

necessary field accuracy: dB/B ~ 10-4

(bending angle errors, longitudinal beam dynamics)


Perspectives for an energy increase of mami c

Increasing the magnetic field of the HDSM dipoles

HDSM dipole 03, field map

(normalized to ideal field gradient, Bmax=1.539T for 1508MeV)

without correction

with correction


Perspectives for an energy increase of mami c

Increasing the magnetic field of the HDSM dipoles

HDSM DIPOLE 02 at higher fields, more details

1508MeV

1.53T, without correction

1.53T with correction


Perspectives for an energy increase of mami c

Missing field:

LINAC-Side

Dispersions-Side

s

s

Shim

Shim

Wedler

Wedler

Increasing the magnetic field of the HDSM dipoles

(angle error ~ mrad)

Correction with thin iron shim (designed for fields at 1.539T)

and corrector magnet !


Perspectives for an energy increase of mami c

1.539 T

1.539 T

Increasing the magnetic field of the HDSM dipoles

We measured field maps for all magnets at

nominal field 1.539T = 1.508GeV (of course)

1.635T = 1.602GeV

1.708T = 1.674GeV

1602MeV

1.635T, without correction

1.635T with correction


Perspectives for an energy increase of mami c

surface correction plates

corrector magnets

shims

Increasing the magnetic field of the HDSM dipoles

corrector magnets system


Perspectives for an energy increase of mami c

Increasing the magnetic field of the HDSM dipoles

corrector magnets system

(design max values: horizontal 3mrad, vertical 2mrad @ 1.5GeV)


Perspectives for an energy increase of mami c

What does that mean ?

First step (ca. 11/2008)

(new colleague in our group, Robert Heine, will start 01.10.08 and will

be in charge to study the possibilities of an energy increase)

Inject 883.1MeV beam, increase HDSM magnetic field by

3.25% to 1.589T and klystron output power by 6.6%

 HDSM = 1557.4MeV

Could (should) work ! Will learn much about the behaviour of the dipoles!

(excitation pattern of corrector magnets)

This test is the basis for all further attempts !

drawback: e.g. strengths of power supply in transfer channel

(to A1) is very near to the limit.

Next steps: Depending on these results and their careful analysis !


Perspectives for an energy increase of mami c

What does that mean ?

  • Any further increase needs:

  • higher extraction energy from RTM3 and therefore complete

  • scaling of linac and all RTMs.

  • E.g. RTM3 dipole PS (609A, 310V) is at [email protected] (96%)!

  • → limit for RTM3 Energy ~900MeV  1585.7MeV max.

  • We are currently checking all components concerning their

  • capabilities.

  • First look: 4 magnets ~ [email protected]

  • injector linac klystron [email protected]

  • 4.90GHz klystron [email protected] and 100mA

  • [email protected] and 50mA

  • proper adjustment (in advance by field measurements and magnet

  • cycling) of the relation of reverse field and main field of all

  • RTM dipoles (not possible just to scale, especially critical at RTM2)

  •  no simple knob for increasing Einj available

  • At certain energies it will require new hardware !


Perspectives for an energy increase of mami c

What does that mean ?

Emax = 1600MeV need EInj=907MeV

(13% increase in rf-Power)

Emax = 1650MeV need EInj=936MeV

(20% increase in rf-power)

  • new power supply for RTM3 dipoles, new injector linac klystron + PS

  • (what else ?)

  • new surface correction plates and shims

  • (needs to be designed based on already existing field maps

  • up to 1.708T = 1.674GeV, not clear if possible because

  • current line density in corners will dramatically increase)

  • their installation would need to dismantle most of the HDSM

  • hardware (4.90GHz linac, return path vacuum system, radiation

  • shielding )

  • For high beam current operation: new 4.90GHz klystrons with

  • higher output power


Perspectives for an energy increase of mami c

Conclusion:

  • 1557MeV HDSM should be possible

  • (will be tested till end of 2008)

  • further exploration depending on results of test

  • - not simple and will most likely need new hardware

  • - at certain energy (my estimation between 1.560GeV and 1.6GeV)

  • new correction plates (very elaborate) necessary

  • - at certain energy klystrons will be at their limit

  • superconducting post accelerator

  • some basics

  • real estate gradient (cw): ~ 10 MV/m  100MeV needs 10m

  • cost: more expensive than HDSM (> 15Mio€)

  • no space where all experimental halls can benefit from increase


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