Update on Beam induced heating

Put together with the invaluable input and help of many colleagues:

Collimation team: Oliver Aberle, Ralph Assmann , Roderik Bruce, Alessandro Bertarelli, Federico Carra, Luca Gentini, Luisella Lari, Frederic Loprette, Roberto Losito, Stefano Redaelli, MarcTimmins, Daniel Wollman

Cryogenics team: Serge Claudet, Laurent TavianKicker team: Chiara Bracco , Mike Barnes, Brennan Goddard, Jan Uythoven RF team: Philippe Baudrenghien, Themistoklis Mastoridis, Juan Esteban Mueller, Elena ShaposhnikovaImpedance team: Gianluigi Arduini, N. Biancacci, Fritz Caspers, Hugo Day, Alexey Grudiev, Elias Métral, Nicolas Mounet, Jean-Luc Nougaret, Giovanni Rumolo, B. SalvantInstrumentation team: Rhodri Jones, Mariusz, Federico Roncarolo, Andriy NosychOperators and OP teamVacuum team: Vincent Baglin, Alexis Vidal, Giulia Lanza, Bernard Henrist, Gregory CattenozAnd the TIMBER team!

Goal of the talk• Follow-up after the overview of the run at the Evian workshop

• Input for talk at Chamonix workshop next week

3

observable Cooling? Limits operation? better if bunch length increased

improves with time?

Is it happening to all similar devices

TCP_B6L7_B1 temperature water Yes, dump in Sept 17th interlock increase from 55 to 70 degrees

yes no No (1/6)

TCTVB.4R2 temperature water Yes, dump in October 9th interlock increase from 50 to 70 degrees

Yes Not obvious No (1/4)

TDI VacuumTemperature (outside tank)

no Not anymore, should be put in parking position

? no Yes (2/2)

MKI Temperature and Rise time and delay (soon)

no Yes (kick strength), and temp interlock increased from 50 deg to 62 deg. Needed to wait 4h in Oct 2011

Yes no All are heating but MKI-8D seems to be heating more No (1/8)

Beam screen Heat load computed from regulation response

yes No, except in one cell Q6R5

Yes no No (only one)

ALFA Temperature on the roman pots

no Not yet (18deg increase in temperature in 2011, with margin of 40 degrees)

? Cooling was needed in TOTEM

VMTSA VacuumSpring broken after May

no Yes (spring broken and dangling fingers)

? Yes

BSRT Mirror Jitter in BSRT measurement

mirror is deforming and RF heating is suspected

N/A

BGI Vacuum Probably not a heating issue

No data N/A

Focus on

• Injection kicker MKI• ALFA detector• VMTSA double bellow• BSRT• Stand-alone Q6R5• Collimators (TCP, TCTVB, TDI)

Injection kicker MKI• Followed up by Hugo Day and Mike Barnes

– Xrays on MKI2 not much space, very difficult to observe anything– Xrays abandoned for the moment for MKI8 (MKI8D and to a lesser extent

MKI8B are an issue)– Simulations and measurements of longitudinal impedance with different

configurations of the RF fingers (talk of Hugo Day at ICE meeting)

H. Day et al

Impedance simulation and measurements (24 conductors)

H. Day et alImpedance simulation and measurements

H. Day et alPower loss estimates

Potential changes in LS1 To be continued

Focus on

• Injection kicker MKI• ALFA detector• VMTSA double bellow• BSRT• Stand-alone Q6R5• Collimators (TCP, TCTVB, TDI)

Beam intensity

Temperatures in 7L1

Temperatures in 7R1

Beam energy

Courtesy Sune Jakobsen et al

Detector temperature should not increase by more than 40 degrees Temperature increased by max 18 degrees in 2011 interesting to note that the temperature increase started already at injection

ALFA detector• Followed up with S. Jakobsen, P. Fassnacht, F. Caspers

and E. Métral• Simulated power losses due to impedance of the

order of 15 W could be consistent with the observed temperature increase (bench measurements)

• Need to decide if the detector should be taken out • Cooling and RF damping system planned to be

modified in LS1 (as for Totem)

Focus on

• Injection kicker MKI• ALFA detector• VMTSA double bellow• BSRT• Stand-alone Q6R5• Collimators (TCP, TCTVB, TDI)

VMTSA• Followed up with J.L. Nougaret, V. Baglin, A. Vidal, B. Henrist, G. Cattenoz, F.

Caspers, E. Metral• Large temperature increase inside the bellow indicated by melting of the

fingers• Up to now, simulations and measurements indicate that the design VMTSA

should not generate significant heating, but runaway effect is feared.• New design with shorter fingers is being installed and is expected to help. • Need to check with RF measurements followed up by Jean Luc, Elias and Fritz

Pictures TE/VSC/LBV

Focus on

• Injection kicker MKI• ALFA detector• VMTSA double bellow• BSRT• Stand-alone Q6R5• Collimators (TCP, TCTVB, TDI)

BSRT mirror system• Followed up with A. Nosych and F. Roncarolo

• Federico observed that the beam spot is consistently moving when beam intensity is increased and coming back when intensity decreases beam induced heating of the mirror or of the holder? Can it damage the system?

• First simulations by Andriy show a significant mode that could cause power loss first discussions yesterday, to be continued

Focus on

• Injection kicker MKI• ALFA detector• VMTSA double bellow• BSRT• Stand-alone Q6R5• Collimators (TCP, TCTVB, TDI)

Q6R5 standalone• Follow up with L. Tavian and S. Claudet

• Xrays were performed around the valve: no obvious metallic obstruction.

• In particular need for a measurement of pressure at the input of the valve as a capillary could obstruct the entrance.

• TE/VSC/LBV performed Xrays on Dec 16 on the RF fingers in the bellows in that zone : Nothing

special is observed

– 13553.366 a 13554.001 (4 soufflets)– 13562.27 a 13562.905 (4 soufflets)

• Interesting to note that TOTEM roman pots are 3 m away. However, warm region so it should

impact.

Need to wait for LS1 to open and diagnose.

Focus on

• Injection kicker MKI• ALFA detector• VMTSA double bellow• BSRT• Stand-alone Q6R5• Collimators (TCP, TCTVB, TDI)

Collimators • followed up with Oliver Aberle, EN/STI, and EN/MME• TCP.B6L7.B1 nothing obvious for that primary, Xrays next week

• TCTVB.4R2 has been removed during the stop should nevertheless check the collimator in storage for

potential issues• TDI opened to check the Ti coating

deformation of the beam screen observed (follow up also with TE/ABT) beam induced heating could be one of the causes, investigated by Alexej

Grudiev and Delio Duarte Ramos (ongoing) phase error measurement during an MD indicate an increase of losses of the order of 1 to 2 kW when closing the TDI jaws fromparking to 3.7 mm half gap.

Phase error measurement with single bunch

TDI full gap

Phase error

0.1 degree

40 mm

With Gianluigi Arduini, Chiara Bracco, Juan Esteban Mueller, Elena Shaposhnikova et al

From phase shift to power loss

• Energy gain per particle:

• Energy gain per particle when moving the TDI out:

• Power per particle when moving the TDI out :

• Power per bunch when moving the TDI out :

sineVE

11106.2

112456

b

rev

N

fMVV

inTDIoutTDIrevTDI eVfP sinsin

inTDIoutTDITDI eVE sinsin

inTDIoutTDIbrevTDI NeVfP sinsin

WWPTDI 7.14.3

7.5

63.5

outTDI

inTDI

In the case of the MD:

Note: empirical error bar to give order of magnitude of noise

With Juan Esteban Mueller, Elena Shaposhnikova et al

Extrapolation from the MD to nominal 50 ns beam (with E. Metral) • Power loss from impedance for M bunches

• Power loss from impedance for a single bunch

If for the studied modes (i.e. Q < 900 for 10 MHz, Q < 90000 for 1 GHz)

In most cases, the sum can be approximated by an integral for for high Q modes in the case of single bunch

In most cases, the sum can not be approximated by an integral for high Q modes in the case of multibunch

1

2 22Re2p

revrevlongrevbloss pMfrumPowerspectpMfZfeMNP

1

2 22Re2p

revrevlongrevbloss pfrumPowerspectpfZfeNP

rev

res

ffQ

0

2 22Re12 dffrumPowerspectfZf

feNP longrev

revbloss

resonatorresonatorlongrevbloss pMfrumPowerspectMfZfeMNP 22Re2 2

As a consequence for a given mode, scaling can be applied with bunch intensity: 2

6.25.1)/116.2()/115.1(

bpePbpeP lossloss

But scaling is not obvious with number of bunches: )1()(0 2 bunchPMbunchesMP lossloss

Phase error measurement with almost filled machine (except the last batch) – 50ns

TDI full gap

Phase error

0.1 degree

intensity

Power lost by the full beam when moving the TDI out :

inTDIoutTDIbrevTDI MNeVfP sinsin

bpN

bunchesMf

MVV

b

rev

/1034.1

1236112456

11

WkWPTDI 3001 12.6

09.6

outTDI

inTDI

In the case of the MD:

Note: empirical error bar to give order of magnitude of noise

With Stefano Redaelli, Juan Esteban Mueller, Elena Shaposhnikova et al

Tentative scaling to 1380 bunches at 1.5e11 p/b

- From single bunch MD ~1.6 kW

- From 1236 bunches MD ~1.3 kW

• Assuming broadband impedance can give an order of magnitude, but may be very off compared to the actual power deposited. However in this case, this scaling is consistent TDI is abroadband impedance?

• To be checked in measurements in physics (if possible…).

• Need to gate the phase error per bunch to decrease noise (Juan and Elena)

Actions for the impedance team• Injection kicker MKI

simulate RF fingers

• ALFA detector wire measurements Predict effect of bunch length Help with system improvement in LS1

• VMTSA double bellowRF measurements and simulations with smaller fingers in conform and non conform situation

• BSRT Assess heat load on the mirror and on the holder

• Stand-alone Q6R5

• Collimators (TCP, TCTVB, TDI) assess heat load on TDI from simulations check the deformation of the shielding foil behind the beam screen before and after the jaw check the TCTVBs taken out of the machine

Other actions?

Thank you for your attention

Power loss estimates vs bunch length for 50 nsH. Day et al

Juan (MD single bunch)

Juan (MD multi bunch)