MTE: plans for 2014M. Giovannozzi

Introduction

What is new in 2014

Commissioning activities

Outlook

Acknowledgements: C. Bertone, J. Borburgh, D. Bodart, R. Brown, S. Burger, S. Damjanovic, P. Demarest, R. Fernandez Ortega, J. A Ferreira Somoza, D. Gerard, S. Gibson, S. Gilardoni, G. Le Godec, C. Hernalsteens, M. Hourican, N. Jurado, J. M. Lacroix, S. Mataguez, G. Métral, C. Pasquino, E. Perez-Duenas, S. Persichelli, B. Salvant, R. Steerenberg, P. van Trappen, and A. Lachaize, SPS-PS OP crew

07/04/2014 1MG - OP Lecture 2014

07/04/2014 MG - OP Lecture 2014 2

Present multi-turn extraction – I

First PS batch Second PS batch Gap for kicker

CSPS = 11 CPS

PSPS

SPS circumference

Beam current transformer in the PS/SPS transfer line

1 2 3 4 5 (total spill duration 0.010 ms)

07/04/2014 MG - OP Lecture 2014 3

Electrostatic septum blade

Present multi-turn extraction – II

Length

Kic

ker

str

en

gth

Four turnsFifth turn

X

X’

13 5

2

4

Slow bump

Slow bump

Electrostatic septum (beam shaving)

Extraction septum

Kicker magnets used to generate a closed orbit bump around electrostatic septum

Extraction line

Efield=0

Efield≠0

07/04/2014 MG - OP Lecture 2014 4

Present multi-turn extraction –III

The main drawbacks of the present scheme are:

Losses (about 15% of total intensity) are unavoidable due to the presence of the electrostatic septum used to slice the beam.

The electrostatic septum is irradiated. This poses problems for hands-on maintenance.

The phase space matching is not optimal (the various slices have “fancy shapes”), thus inducing betatronic mismatch in the receiving machine, i.e. emittance blow-up.

The slices have different emittances and optical parameters.

07/04/2014 MG - OP Lecture 2014 5

Novel multi-turn extraction – I

The main ingredients of the novel extraction:

The beam splitting is not performed using a mechanical device, thus avoiding losses. Indeed, the beam is separated in the transverse phase space using

Nonlinear magnetic elements (sextupoles ad octupoles) to create stable islands.Slow (adiabatic) tune-variation to cross an appropriate resonance.

This approach has the following beneficial effects:Losses are reduced (virtually to zero).The phase space matching is improved with respect to the present situation.The beamlets have the same emittance and optical parameters.

07/04/2014 MG - OP Lecture 2014 6

Novel multi-turn extraction - III

Tune variation

Phase space portrait

Simulation parameters:

Hénon-like map (i.e. 2D polynomial – degree 3 - mapping) representing a FODO cell with sextupole and octupole

07/04/2014 MG - OP Lecture 2014 7

Novel multi-turn extraction – IV

Final stage after 20000 turns (about 42 ms for PS)

About 6 cm in physical space

• Slow (few thousand turns) bump first (closed distortion of the periodic orbit)

• Fast (less than one turn) bump afterwards (closed distortion of periodic orbit)

Bfield ≠ 0Bfield = 0

At the extraction septum location

Pros and cons of extraction methods

Continuous TransferIntrinsically lossy (slicing is performed by a mechanical device).

Slices have different emittances or intensities: it is not possible to equalise both simultaneously.

Not so good phase space matching.

Relatively easy to implement.

Multi-Turn ExtractionIntrinsically lossless (losses on SMH16 are due to longitudinal beam structure)

First four beamlets have exactly the same emittance and intensity. The fifth one is different, but difference can be optimised.

Good phase space matching.

Less easy to implement: it pushes all systems to limits.

07/04/2014 MG - OP Lecture 2014 8

What is new in 2014 - I

07/04/2014 MG - OP Lecture 2014 9

Observed issues in 2010PS magnetic septum activation

Due to losses during the rise time of the extraction kickers because of the longitudinal beam structure.

Mitigation measure: dummy septumProvide shadowing of magnetic septum

Create a localised loss point in the ring

Fluctuation of beam trappingInvestigate the beam excitation system (PS damper).

Fluctuation of injection trajectories in SPSMagnetic field at PS

Closure of extraction bumps

What is new in 2014 - II

Shadowing of SMH16 bladeIdeally it should be located in the same section as SMH16 to provide a geometrical shadowing.

Only place available in SS15: this reduces a bit its effectiveness.

Detailed numerical simulations (combined MAD-X-PTC-FLUKA) to assess efficiency of the solution.

07/04/2014 MG - OP Lecture 2014 10

Courtesy C. Hernalsteens

What is new in 2014 - III

07/04/2014 MG - OP Lecture 2014 11

Courtesy C. Hernalsteens

What is new in 2014 - IV

07/04/2014 MG - OP Lecture 2014 12

Courtesy C. Hernalsteens

What is new in 2014 - V

07/04/2014 MG - OP Lecture 2014 13

Courtesy C. Hernalsteens

Hardware changes - I

07/04/2014 14MG - OP Lecture 2014

Status of dummy septum:Hardware installed

Vacuum tests: passed

Blade local control tests: passed

Local BTV control tests: passed

Final report: in publication

BI assembly

Camera Assembly

Beam Impedance screen

Support Block

Support system

Drive assembly

Position Measurement

Motors

Blade and support table

In Stock

To manufacture

To order Off shelf

Hardware changes - II

07/04/2014 15MG - OP Lecture 2014

Motor

Dummy septum blade Beam impedance screen

Circulating Beam

Actuator rods/bellows Ejected Beam

Hardware changes - III

07/04/2014 16MG - OP Lecture 2014

Two elements to be relocated:Quadrupole: gamma-jump.

An additional element already

installed in SS99 and used since

April 2012 in normal operation.

During LS1: removal of quadrupole

from SS15.

Dipole: DHZ15 to be used to correct the closed orbit distortion at top energy (original function). Recently, also used for the slow extraction bump.

Several alternative solutions studied in 2012/13 both on paper and with beam.

Detail covered by C. Hernalsteens in his OP lecture

Hardware changes - IV

07/04/2014 17MG - OP Lecture 2014

Best configuration retained (implementation in YASP straightforward):

SS05: One dipole corrector.

Everything already in place (installation made during 2012 winter stop).

Power converter from DHZ15.

SS18: One dipole corrector

already in place.

Power converter: see later.

SS60: Everything already in

place.

Closed orbit correction for an LHC-like beam

Hardware changes - IV

07/04/2014 18MG - OP Lecture 2014

The dipole in SS18 has two distinct functions:

Generate the slow extraction bump for MTE

Correct the closed orbit distortion for high-energy beams.

The first function is particularly demanding in terms of voltage.

The second function is rather easy in terms of performance. -120

-100

-80

-60

-40

-20

00 500 1000 1500 2000 2500 3000

Curr

ent (

A)

Time (ms)

GFA for LHC

0

50

100

150

200

250

300

995 1000 1005 1010 1015

Curr

ent (

A)

Time (ms)

GFA for MTE

Very different time scale

Hardware changes - V

Situation of power convertersProgrammable power converter of DHZ15 will power the dipole in SS5 during the 2014 physics run. A power converter of type S250 will be built to be installed in Bldg. 355 and finally connected to dipole in SS5 for early 2015. The programmable power converter will then be moved to Bldg. 365 to become a spare.

The spare of the programmable power converters installed in Bldg. 365 will be used for the dipole in SS18. The programmable power converters in Bldg. 365 are used for MTE (sextupoles and octupoles) and slow extraction (quadrupoles, sextupoles, and slow bumps). In case of problems with one of the operational converters, one used for the MTE sextupoles could be used, without any severe impact on MTE operation.

The capacitor discharge power converter connected to the dipole in SS18 till 2013 will be disconnected and used as a spare for the power converters of the slow bump.

07/04/2014 MG - OP Lecture 2014 19

Extraction trajectories changes - I

Hardware changes triggered also changes in the extraction trajectories.

Reduction of amplitude at the location of the dummy septum.

Optimised beams:TOF (dedicated and parasitic)

High-energy beamsAD

LHC

Approach: make use of the several kickers installed in the PS to improve extraction trajectory.

07/04/2014 MG - OP Lecture 2014 20

Extraction trajectories changes - II

LHC beams (protons and ions)Improved closed orbit correction

Improved closure of the new slow bump

Same extraction conditions

Proton beams delivered to SPS and LHC at the end of 2012 physics run: no difference in performance observed.

07/04/2014 MG - OP Lecture 2014 21

Extraction trajectories changes - III

nTOF beams (dedicated – 20 GeV/c - and parasitic – EAST cycle)

Improved closed orbit correction

Improved closure of the new slow bump

Extraction trajectory: four kickers usedKFA21

KFA71/79

KFA4

KFA13

Proton beams delivered to

physics from 12 to 16

December 2012: no

difference in performance

observed.07/04/2014 MG - OP Lecture 2014 22

Dedicated nTOF

For the parasitic nTOF beam, the bunch for EAST Hall sees a fast closed bump between KFA13 and 21.

The pulse is 5 turns!

Extraction trajectories changes - IV

AD beamImproved closed orbit correction

Improved closure of the new slow bump

Extraction trajectory: three kickers usedKFA21

KFA71/79

KFA13

Proton beam delivered

to AD target for

physics run on 15 and

16 December 2012: no

difference in

performance observed.

07/04/2014 MG - OP Lecture 2014 23

Comments on new extraction trajectories

Of course, the situation is more complicated than in the original configuration.

More burden on OP. However:Performance improved not only for MTE (lower losses).

Tools can be provided to set up trajectories.

More kickers could mean:Higher failure rates: checked with L. Sermeus and no show stopper identified.

In case of kicker failure one can always go back to the original scheme and put the dummy septum in parking position.

No added complexity for the LHC fast extraction!07/04/2014 MG - OP Lecture 2014 24

Commissioning: instrumentation

The commissioning of the new fast extractions including the dummy septum, requires the availability of

ring BCT

orbit system

BLMs (including the fast signals for PE.BLM15 and PE.BLM16 or equivalently of the PE.FBLM15 and PE.FBLM16 connected to OASIS)

MTV in SMH16 (PE.MTV16) and the BTV of the TPS15 (PE.MTV15).

SPS-type BPMs and the new F16.UDC106

several BCTs available in TT2-TT10.

The beam profiles will be measured by both the TT2 OTRs (F16.MTV201, F16.MTV218, F16.MTV229, and F16.MTV241) and the SEM grids or wires depending on the beam size.

The logging of the TT2 pickups will be available in TIMBER, it is not clear yet whether the logging of the OTR images will be possible.

07/04/2014 MG - OP Lecture 2014 25

Commissioning: extraction elements

Concerning the extraction elements:All the kickers should be available since the first day of the run, i.e., PE.KFA13, PE.KFA21, PE.KFA4, PE.BFA9 (pedestal and staircase), PE.BFA21 (pedestal and staircase) and PE.KFA71.

The SPS requires, as part of the beam commissioning, a 1-turn CT extracted beam for setting-up. For this reason, also the electrostatic septum PE.SEH31 should be operational.

The operation of the fast extracted beams will be resumed after LS1 with the new bump configurations tested during the end of the 2012-2013 run, but now with the dummy septum in place.

07/04/2014 MG - OP Lecture 2014 26

Commissioning: software tools

A LabView-based proto-type software needed for the correct setting up of the extraction was developed and tested already during the 2012-2013 run, and a final Java-based version should be available since early stages of 2014 start-up. In particular:

The high energy orbit correction for the 26 GeV/c beams will be computed by YASP, taking into account the new correctors PE.DHZ05, PE.BWS16-18 as well as the PE.DHZ60 already used in the past.

The slow and fast bump closure, and the evaluation of the RF correction for the fine synchronization during the rise of the slow bump required for the LHC-type beams, will be performed by a dedicated application developed in JAVA by OP specialists. A first version of the application written in LABVIEW was already in use during the 2012-2013 run.

The trajectory steering in the TT2 line will be performed by YASP. The newly installed pickup F16.UDC106 will be included in the list of the available monitors.

07/04/2014 MG - OP Lecture 2014 27

Commissioning: cold checkout

A number of tests should be performed to ensure the correct functioning of the dummy septum mechanics, with special care to the blade movement and the correct positioning of the BTV screen:

Check of blade movements with remote control including also putting the blade in park position.

Check the blade movement with manual system.

Check the movement of the screens and the cameras of PE.MTV15 and PE.MTV16.

Check of movement of the screen of PE.MTV15 when the blade is displaced.

Check the correctness of the blade position given by the control system with respect to the position red by the motor controls in the tunnel.

07/04/2014 MG - OP Lecture 2014 28

Commissioning: schedule - I

07/04/2014 MG - OP Lecture 2014 29

1. New fast extractions with dummy septum

2. MTE beam

Commissioning: schedule - II

The new extraction schemes including the correct position of the TPS15 blade should be put in operation before the start of the physics run for the AD and nTOF facilities to avoid lengthy iterations in the setting up process.

The first beam should be available in the PS by the end of week 25. The beam setting up, including the re-commissioning of the beam instrumentation, would take about one week. During that week, the beams will be extracted with the same slow and fast bumps used during the last period of the 2012-2013 run, but it is unlikely that systematic measurements could be possible in view of performing a proper setting up of the dummy septum.

The studies to position the dummy septum blade could take place in week 27.

The blade is not PPM: the best location should be identified in dedicated beam time.

07/04/2014 MG - OP Lecture 2014 30

Commissioning: beams required

The beams needed for setting up:nTOF– like beam, also at intensity lower than nominal and with no bunch rotation before the extraction. An optimisation of the transverse emittances in the PSB is required, in particular for the H-plane, to increase the available aperture at the location of TPS15.

AD – like beam to set up the extraction at 26 GeV/c.

EAST – like beam with the parasitic nTOF bunch.

Small-emittance, low-intensity, single-bunch beam at h=8 on a 26 GeV/c and 20 GeV/c cycles without bunch rotation at the end of the cycle. This beam will be used to measure trajectories and available aperture during the fast extraction.

Pencil-like beam to kick in the islands and set up MTE extraction.

MTE nominal beam.

Setting up of LHC-type beams with the new extraction (this depends on when the LHC beams will be available).

07/04/2014 MG - OP Lecture 2014 31

Commissioning: strategy - I

a) The extraction septum PE.SMH16 blade should be put at the nominal position.

b) New slow and fast bumps for a nTOF-type beam at 20 GeV/c (starting with a low intensity beam). This should be followed by a comparison of measured and model extraction trajectories. The transfer lines TT2 and FTN should be steered with special care. If possible, the optics of TT2 and FTN should be re-measured.

c) The setting up of the EAST cycle with parasitic nTOF beam should be done at 24 GeV/c. Particular attention should be paid to the closure of the fast bump for the EAST bunch.

d) New slow and fast bumps for an AD type beam at 26 GeV/c (same as nTOF). The optimization of the trajectories should be repeated with AD to optimize the pbar production rate. The optics of TT2 and FTA should be re-measured.

07/04/2014 MG - OP Lecture 2014 32

Commissioning: strategy - II

e) Setting up of bump and extraction for 1-turn CT beam at 14 GeV/c. In this case there is no need of measuring optics in extraction lines.

f) New slow and fast bumps for a LHC-type single bunch beam at 26 GeV/c (same as nTOF and AD beam). TT2 optics should be re-measured. Once the SPS will be available, probably in September 2014, a second campaign of optics measurements will be done including TT10 and the SPS to evaluate any optical mismatch. The measurements in TT10, in particular of the dispersion function, could be advanced depending on availability of transfer line magnets and instruments.

07/04/2014 MG - OP Lecture 2014 33

Commissioning: strategy - III

g) The dummy septum should be put in nominal position and then losses should be optimized by moving the blade.

For the fast extracted beams there should be no losses at the location of the PE.TPS15, thanks to the optimization of the extraction trajectories.

No losses should be observed on PE.BLM15 or the fast one BLM PR.FBLM15.

The beam trajectory and shape should be checked at PE.MTV15, PE.MTV16 and TT2 SEMGRIDs.

The PE.TPS15 blade movement is non-PPM, a unique position will be declared operational for all the beams.

End of first part of beam commissioning!

07/04/2014 MG - OP Lecture 2014 34

Commissioning: strategy - IV

h) MTE beam extraction set up should take place in two steps.

A pencil beam with one single bunch should be kicked in the islands and then extracted.

The last turn trajectories will be adjusted to jump septum blade.

The procedure should be repeated with bunched, and de-bunched beam.

In a second stage, a nominal beam should be used and the extraction trajectories optimized as for the first step.

Any further optimization of blade position and angle should be followed by a cross check with non-MTE beams.

i) The setting up of the multi-bunch LHC type beam extraction will be performed according to the procedure sketched at point f), considering that the blade position at that moment should be already optimized.

07/04/2014 MG - OP Lecture 2014 35

Outlook

Intense efforts devoted to:Devise a mitigation measure to irradiation of SMH16: dummy septum.

Installation successfully completed

Hardware tests in progress

Beam commissioning strategy prepared and ready (also for comments and improvements…)

The success of this enterprise depends on your help and support!

Thank you!07/04/2014 MG - OP Lecture 2014 36