Perspectives for an energy increase of MAMI C Andreas Jankowiak Institut für Kernphysik Johannes Gutenberg – Universität Mainz 23.09.2008 Cristal Ball

Perspectives for an energy increaseof MAMI C

Andreas JankowiakInstitut für Kernphysik

Johannes Gutenberg – Universität Mainz

23.09.2008Cristal Ball @ MAMICollaboration Meeting

Andreas Jankowiak, Institut für Kernphysik, Johannes Gutenberg – Universität Mainz CB@MAMI

Present situation

• 855.3MeV, E=0.013MeV (0.001%) (883.1MeV maximum)• max. 103A cw current• h=8 nm rad, v=0.5 nm rad (allows for beam foci of ~m)• Halo: < 10-5 at r > 5∙r

MAMI B


Present situation

• 1508.4MeV, E=0.100MeV (0.007%)• max. 100A cw current (successful tested)• h=12 nm rad, v=2 nm rad (measured, v definitely overestimated)

MAMI C


What defines the end energy of an RTM:

1

ii+1

E

dmagnet distance

EInj (1)

2•R

Eout=EInj+z•E

dynamic coherence-condition:

)R2( nLL rfi1i

rfn2

BceE

static coherence-condition:

rf1 kL

rf

Inj kd2Bce

)EE(2

k,n: integer numbers


• increase B and adjust E to full fill dynamic condition

• adjust Einj to full fill static condition

rfn2

BceE

rf

Inj kd2Bce

)EE(2

Increasing the end energy of an RTM:

Energy increase by factor means:

outinjout

injinj

EEzEE

EE , EE , BB


What defines the end energy of a DSM

Injection (E0)

R0

Linac 2 (E)

Linac 1 (E)

L

R0+ R

D

Quadrupole lens

R0+2 R

dynamic coherence-condition:static coherence-condition:

rfn22Bce

E

rf

inj

21

k2Bce

EDL2

E2zEE injout

Einj

k,n=1: integer numbers

Energy increase by factor means (as for RTM):

injinj EE , EE , BB


What defines the end energy of a HDSMIn reality our machine (Harmonic Double Sided Microtron) is

“a little bit more complicated”but the scaling is the same !

0 5 10 15 20 25 30 35 40

6

8

10

12

14

16

18

0 10 20 30 40800

1000

1200

1400

1600

Energy increase by factor means (as for RTM):

Energy gain per turn

total

linac II (2.45GHz)

linac I (4.90GHz)

beam energy

Einj=855.11MeV

Eout=(1508.4±0.4) MeV

Bmax=1.539T

injinj EE , EE , BB


Eout=1508.4MeV

Eout=855.30MeVEin

Ein=855.12MeV

Eout=180.03MeV

Ein

Eout=14.86MeV

Ein=3.97MeV

Energy of the HDSM

Therefore:Changing the maximum energy by factor implies scaling of all machines by factor (E and B fields)

The maximum energy of RTM3 usedso far is: 883.1MeV !

Scaling the HDSM by 883.1/855.3 (+3.25%)results in 1557.4MeV beam energyof the HDSM.


Increasing the magnetic field of the HDSM dipoles

-0,4 -0,2 0,0 0,2 0,4 0,6 0,8 1,0 1,2

0,0

0,1

0,2

0,3

0,4

0,5

0,6

0,7

0,8

0,9

1,0

1,1

1,2

1,3

1,4

1,5

1,6

Polschuh-Kante

60% Bmax

Bmax

=1.539T

By

[T]

z [m]

defo

cusin

g

focu

ssing

remember: dipoles incorporates field gradient perpendicularto the pole face to compensate vertical defocusing

necessary field accuracy: B/B ~ 10-4

(bending angle errors, longitudinal beam dynamics)



HDSM dipole 03, field map(normalized to ideal field gradient, Bmax=1.539T for

1508MeV) without correction

with correction


Increasing the magnetic field of the HDSM dipolesHDSM DIPOLE 02 at higher fields, more details

1.53T, without correction 1.53T with correction 1508MeV


Wedler

Shim

s

LINAC-Side

Wedler

Shim

s

Dispersions-Side


Missing field: Tm 103~dsB 3

Correction with thin iron shim (designed for fields at 1.539T)and corrector magnet !

(angle error ~ mrad)


1.539 T 1.539 T


We measured field maps for all magnets atnominal field 1.539T = 1.508GeV (of course)

1.635T = 1.602GeV1.708T = 1.674GeV

1.635T, without correction 1.635T with correction 1602MeV


surface correction plates

shimscorrector magnets

Increasing the magnetic field of the HDSM dipolescorrector magnets system


correctors between dipole 3 + 4

horizontal

vertical

correctors between dipole 1 + 2

horizontal

vertical

steerer first ×

steerer second +

ho

r.[m

rad]

ve

rt.[m

rad

]

turn No. i

0 5 10 15 20 25 30 35 40 45-1.00

-0.75

-0.50

-0.25

0.00

0.25

0.50

0.75

1.00

0 5 10 15 20 25 30 35 40 45-1.00

-0.75

-0.50

-0.25

0.00

0.25

0.50

0.75

1.00

0 5 10 15 20 25 30 35 40 45-1.00

-0.75

-0.50

-0.25

0.00

0.25

0.50

0.75

1.00

0 5 10 15 20 25 30 35 40 45-1.00

-0.75

-0.50

-0.25

0.00

0.25

0.50

0.75

1.00

Increasing the magnetic field of the HDSM dipolescorrector magnets system

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


What does that mean ?

First step (ca. 11/2008)(new colleague in our group, Robert Heine, will start 01.10.08 and willbe in charge to study the possibilities of an energy increase)

Inject 883.1MeV beam, increase HDSM magnetic field by3.25% 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 !

rfP~E



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 582A@883MeV (96%)! → limit for RTM3 Energy ~900MeV 1585.7MeV max.

We are currently checking all components concerning their capabilities.

First look: 4 magnets ~ 95%@883MeV injector linac klystron 100%@906MeV 4.90GHz klystron 100%@1508MeV and 100A 100%@1600MeV and 50A

• 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 !



• 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

Emax = 1600MeV need EInj=907MeV(13% increase in rf-Power)

Emax = 1650MeV need EInj=936MeV(20% increase in rf-power)


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

Documents

Perspectives for an energy increase of MAMI C Andreas Jankowiak Institut für Kernphysik Johannes Gutenberg – Universität Mainz 23.09.2008 Cristal Ball