id stringlengths 36 36 | text stringlengths 1 1k | source stringlengths 42 191 | page int64 0 1.03k |
|---|---|---|---|
9db75c77-4467-4907-a471-fcc3b71a4157 | likely .
Apart the few modes with large (R/Q), many modes have
(R/Q) around one and mostly TM modes . As one can see
in Fig. 2, TE modes above 2 GHz have an amplitude close
to zero. So, we focused on longitudinal modes. Although individually weak, their large number could still have an
effect.
Table 2: Longitu... | D:\Daily_ihep\Conferences\IPAC2026\WEP\WEP5089.pdf | 1 |
5971f081-4239-44f4-a3ef-1d148839c6b3 | ext are shown in Fig. 3 and in Fig. 4,
respectively.
Figure 3: longitudinal R/Q for modes within 1 MHz from
the nearest beam harmonic frequency as a function of fre-
quency.
Figure 4: Qext of longitudinal modes within 1 MHz from
the nearest beam harmonic frequency as a function of fre-
quency.
17th In... | D:\Daily_ihep\Conferences\IPAC2026\WEP\WEP5089.pdf | 1 |
dad01bba-8411-4f36-b079-4db1df22cd07 | It is possible to assess the voltage induced by the beam
using equation 2.
Vind = 𝑅𝑅
𝑄𝑄𝑄𝑄𝐿𝐿𝑇𝑇2Iharm (2)
With loaded Q, Q L ≈ Q ext and I harm ≈ 2I b√2𝜋𝜋𝑓𝑓𝑟𝑟𝑟𝑟𝑟𝑟
𝜎𝜎𝑓𝑓 with σf
(equal to 16 GHz) is the standard deviation of the fre-
quency spectrum of the beam and T is the transit time fac... | D:\Daily_ihep\Conferences\IPAC2026\WEP\WEP5089.pdf | 2 |
d507ad24-a223-4e0a-b45a-33ff4b041c5b | value for all the modes. Summing all modes gives a total
voltage of 0.24 V and a power of 5 mW, which is very
small.
BEYOND 8 GHZ
So far, we showed all the modes found in the RF simu-
lations and discarded them either because their frequencies are too far from a beam harmonic or their amplitude being
negligible. ... | D:\Daily_ihep\Conferences\IPAC2026\WEP\WEP5089.pdf | 2 |
3402de63-b23e-4ab2-92e2-20985740c3a8 | below 8 GHz, we estimate a total voltage of 8. 5 V and a power of 0.17 W. This represents an overestimation, as it assumes the same harmonic current up to 32 GHz, whereas
the current actually decreases according to the Gaussian
shape of the beam spectrum. The induced voltage is negli-
gible compared to the acceler at... | D:\Daily_ihep\Conferences\IPAC2026\WEP\WEP5089.pdf | 2 |
0a835e55-ac13-4a7c-80c1-4e6af7197f5f | Then we deduced the number of modes within 1 MHz from
the beam harmonics and evaluated the induced voltage and
the power up to 32 GHz. The total voltage seems to be neg-
ligible compared to the accelerating voltage of 9 MV/m.
Regarding the HOM power, it is evacuated from the cavity
because it is well above the cut ... | D:\Daily_ihep\Conferences\IPAC2026\WEP\WEP5089.pdf | 2 |
e6edb861-6dd1-4d77-9fb7-e789792d16f8 | is designed for the PERLE ERL linac which is based on 5
cells cavities .
REFERENCES
[1] S. A. Boga cz et al., “Beam dynamics driven design of pow-
erful energy recovery linac for experiments”, Phys. Rev. Acc.
And Beams 27, 031603 (2024).
doi:10.1103/ PhysRevAccelBeams.27.031603
[2] R. Roux et al ., “Status ... | D:\Daily_ihep\Conferences\IPAC2026\WEP\WEP5089.pdf | 2 |
7275e414-b883-4893-a35a-7163c3efb7ed | ISBN: 978-3-95450-252-3 ISSN: 2673-5350 doi: 10.18429/JACoW-IPAC2026-WEP5089
MC5.D04: Beam Coupling Impedance Theory, Simulations, Measurements, Code Development 2473WEP: Poster session WEP5089
Content from this work may be used under the terms of the CC BY 4.0 licence (© 2026). Any distribution of this work must maint... | D:\Daily_ihep\Conferences\IPAC2026\WEP\WEP5089.pdf | 2 |
0944c002-cf2a-4ffc-a70f-0710c88e26d1 | IMPROVED RESISTIVE WALL EFFECTIVE RADIUS TAKING INTO
ACCOUNT YOKOYA FACTORS
A. Gamelin∗, V. Gubaidulin, Synchrotron SOLEIL, Saint-Aubin, France
S. Thakur, Deutsches Elektronen-Synchrotron DESY, Hamburg, Germany
Abstract
When computing the resistive wall impedance, one must
accountforvariationsinbeampipeaperture,conduct... | D:\Daily_ihep\Conferences\IPAC2026\WEP\WEP5091.pdf | 0 |
86f08b83-e578-4522-81a5-cbf2d1f7ab87 | impedance model, significantly improving the agreement
between simulated and measured instability thresholds.
INTRODUCTION
Theresistivewallimpedance,describingthewaythebeam
interacts with the resistive part of the beam pipe walls, is
akeycomponentpresentin allimpedancemodels madeto
studycollectiveeffectsinsynchrotrons.... | D:\Daily_ihep\Conferences\IPAC2026\WEP\WEP5091.pdf | 0 |
8aac72c8-7a42-4066-b0be-cf87e6cb4993 | in different sections with the same properties and then sum-
mingthedifferentcontributions. Anotherwayistocompute
an “effective radius” [3], which can then be used in analytic
expressionstogettheresistivewallimpedanceforthefull
accelerator.
RESISTIVE WALL EFFECTIVE RADIUS
Theresistivewalleffectcanbesplitintoitsshort-ra... | D:\Daily_ihep\Conferences\IPAC2026\WEP\WEP5091.pdf | 0 |
596b49b0-da18-45a8-97d4-1bc2a2996361 | efffor power 𝑛[3,
Eq. (27)], is defined as:
𝑎(𝑛)
eff= √
𝜎∗
𝐿𝛽∗∑︁
𝑖𝑙𝑖𝛽𝑖
𝑎𝑛
𝑖√𝜎𝑖!−1/𝑛
(1)
wherethesummationontheindex 𝑖correspondstothedif-
ferentbeampipecomponentsinthering, 𝑙𝑖isthecomponent
length, 𝑎𝑖itsaperture, 𝛽𝑖thebetafunctionatitslocation, 𝜎𝑖
itsconductivityand 𝐿=Í𝑙𝑖isthetotallength. T... | D:\Daily_ihep\Conferences\IPAC2026\WEP\WEP5091.pdf | 0 |
cda92a7a-e54a-459d-93ee-0b35581167b6 | enceofonedimensionontheotherisneglected(forexample
theimpactofthehorizontalapertureontheeffectivevertical
radius). Finally, the present definition does not take into
account quadrupolar or monopolar wakes.
MODIFIED FORMULA USING YOKOYA
FACTORS
Weproposeanewdefinitionoftheeffectiveradiusaiming
to solve the issues raised... | D:\Daily_ihep\Conferences\IPAC2026\WEP\WEP5091.pdf | 0 |
7fc58415-9ccc-441b-a2af-06dac01dba92 | 𝑟𝑛
min𝑖√𝜎𝑖!−1/𝑛
(3)
Where 𝑛=1forlongrangeand 𝑛=2forshortrangeregime.
For the horizontal and vertical dipolar effective radius, it is
defined as:
𝑟(𝑛)
xdip= √
𝜎∗
𝐿𝛽∗𝑥∑︁
𝑖𝑌xdip,𝑖𝑙𝑖𝛽𝑥𝑖
𝑟𝑛
min𝑖√𝜎𝑖!−1/𝑛
(4)17th International Particle Accelerator Conference, Deauville, France JACoW Publishing
ISBN... | D:\Daily_ihep\Conferences\IPAC2026\WEP\WEP5091.pdf | 0 |
612e4d55-76c2-4aa7-a80e-5cdced4d2815 | 𝑟(𝑛)
ydip= √
𝜎∗
𝐿𝛽∗𝑦∑︁
𝑖𝑌ydip,𝑖𝑙𝑖𝛽𝑦𝑖
𝑟𝑛
min𝑖√𝜎𝑖!−1/𝑛
(5)
For the horizontal and vertical quadrupolar effective radius,
it is defined as:
𝑟(𝑛)
xquad=± √
𝜎∗
𝐿𝛽∗𝑥∑︁
𝑖𝑌xquad,𝑖𝑙𝑖𝛽𝑥𝑖
𝑟𝑛
min𝑖√𝜎𝑖 −1/𝑛
(6)
𝑟(𝑛)
yquad=± √
𝜎∗
𝐿𝛽∗𝑦∑︁
𝑖𝑌yquad,𝑖𝑙𝑖𝛽𝑦𝑖
𝑟𝑛
min𝑖√𝜎𝑖 ... | D:\Daily_ihep\Conferences\IPAC2026\WEP\WEP5091.pdf | 1 |
4d8a5e84-065f-421e-9c71-36b50368b27d | dielectric or ferromagnetic materials.
FORMULA FOR MONOPOLAR WAKE
When a beam is going off-center in a vacuum chamber,
orwhenthechamberisright/leftortop/downasymmetric,
then a monopolar wake component appears [5–7].
Monopolar wake from an off-center device
Thegeneralwakefunctioninthehorizontalplane 𝑊𝑥can
be written a... | D:\Daily_ihep\Conferences\IPAC2026\WEP\WEP5091.pdf | 1 |
113346e9-4df3-4e0c-9ee1-30d90b012b82 | 𝑆
+𝑊quad(𝑧)𝑥′
𝑇(9)
Where 𝑥′
𝑆and𝑥′
𝑇are the new source and test positions in
thereferentialtranslatedby 𝑥1tobecenteredonthebeam.
Thismakesitclearthat 𝑊mono(𝑧)=𝑊 dip(𝑧)𝑥 1+𝑊quad(𝑧)𝑥 1
for an off-center beam. Physically, moving the beam in
one directionis similarto movingthe chamber inthe other
directio... | D:\Daily_ihep\Conferences\IPAC2026\WEP\WEP5091.pdf | 1 |
9ff26e61-c516-4d08-b519-24ee8bd5e6b6 | crosssection 𝑊monotothedipolarwakeofacircularchamber
𝑊dip,circ:
𝑊mono(𝑧)=𝑌 mono𝑊dip,circ(𝑧)(12)
Expressing the monopolar wake 𝑊monousing previous ex-
pression, we get:
𝑊mono(𝑧)≈𝑊 dip(𝑧)Δ+𝑊 quad(𝑧)Δ
≈𝑌dip𝑊dip,circ(𝑧)Δ+𝑌 quad𝑊dip,circ(𝑧)Δ
≈Δ(𝑌dip+𝑌quad)𝑊dip,circ(𝑧)(13)
Which gives:
𝑌mono≈Δ(𝑌dip+... | D:\Daily_ihep\Conferences\IPAC2026\WEP\WEP5091.pdf | 1 |
614f7fab-a47f-4b82-8d2c-9d15bca67999 | (15)
𝑟(𝑛)
ymono=± 1
𝐿√︄
𝜎∗
𝛽∗
1/2,𝑦∑︁
𝑖𝑌ymono,𝑖𝑙𝑖√︁𝛽𝑦𝑖
𝑟𝑛
min𝑖√𝜎𝑖 −1/𝑛
(16)
With±=+if the sum is positive, ±=−otherwise. Where
𝑛=3for long range wake and 𝑛=4for short range wake
(asmonopolarwakesderivefromdipolarandquadrupolar
wakes). Asmonopolarwakesareonlyweightedbysquare
root of beta fu... | D:\Daily_ihep\Conferences\IPAC2026\WEP\WEP5091.pdf | 1 |
d8e22169-3823-4548-80fe-11aa55e36fd6 | ISBN: 978-3-95450-252-3 ISSN: 2673-5350 doi: 10.18429/JACoW-IPAC2026-WEP5091
MC5.D04: Beam Coupling Impedance Theory, Simulations, Measurements, Code Development 2475WEP: Poster session WEP5091
Content from this work may be used under the terms of the CC BY 4.0 licence (© 2026). Any distribution of this work must maint... | D:\Daily_ihep\Conferences\IPAC2026\WEP\WEP5091.pdf | 1 |
6604adee-6d00-41f5-b205-432a1115edae | Table 1: Resistive Wall Effective Radius for SOLEIL Storage Ring (𝛽∗
𝑥=7.91m,𝛽∗
𝑦=8.11m,𝜌∗=3.33×10−8Ωm)
Formula ID Long Range (mm) Short Range (mm)
configuration𝑟(1)
long𝑟(3)
xdip𝑟(3)
ydip𝑟(3)
xquad𝑟(3)
yquad𝑟(2)
long𝑟(4)
xdip𝑟(4)
ydip𝑟(4)
xquad𝑟(4)
yquad
Original Open 5.19 28.8 7.93 / / 7.41 28.82 7.81 ... | D:\Daily_ihep\Conferences\IPAC2026\WEP\WEP5091.pdf | 2 |
0029260b-2c8d-4a8a-a55c-de39df18e12f | two [10].
AnewimpedancemodelforSOLEILwasdevelopedto
address previous discrepancies [11]. Key improvements in-
clude using the modified effective radius (this paper) for
resistive wall calculations—the dominant impedance con-
tributor—andaddingquadrupolarresistivewallwakesvia
quadrupolareffectiveradius. Themodel’sfreque... | D:\Daily_ihep\Conferences\IPAC2026\WEP\WEP5091.pdf | 2 |
2a9ccbba-bfe3-452c-8ba7-25e87193b630 | The longitudinal effective radii 𝑟(𝑛)
longremain similar be-
tween the original and modified formulas. However, the
modifiedformulayieldsslightlylargerverticaleffectiveradii
𝑟(𝑛)
ydipdue to the larger horizontal aperture ( 𝑌ydip≈0.823).
ForopenIDs,thehorizontaleffectiveradii 𝑟(𝑛)
xdiparesignif-
icantly smaller i... | D:\Daily_ihep\Conferences\IPAC2026\WEP\WEP5091.pdf | 2 |
23e23952-2dfa-4783-a58d-93ca10165da9 | observed at ESRF [14].
Theresistivewallimpedanceiscomputedusing IW2D[2]
using the short-range effective radius, including a 0.5µm
layer of NEG ( 𝜌𝐷𝐶=1.25×10−6Ωm). Figure 2 shows
the new impedance model of SOLEIL, with its real part
of the longitudinal and vertical dipolar impedance. This
new impedance model has been... | D:\Daily_ihep\Conferences\IPAC2026\WEP\WEP5091.pdf | 2 |
b89c7ff0-f767-4e96-a548-5c70a9147043 | and simulation.17th International Particle Accelerator Conference, Deauville, France JACoW Publishing
ISBN: 978-3-95450-252-3 ISSN: 2673-5350 doi: 10.18429/JACoW-IPAC2026-WEP5091
2476 MC5.D04: Beam Coupling Impedance Theory, Simulations, Measurements, Code DevelopmentWEP5091 WEP: Poster session
Content from this work m... | D:\Daily_ihep\Conferences\IPAC2026\WEP\WEP5091.pdf | 2 |
4e860e7e-849b-4c34-93d5-1d98f562cc5b | REFERENCES
[1]A.Chao,Physicsofcollectivebeaminstabilitiesinhighen-
ergy accelerators. Wiley, 1993.
[2]N.MounetandE.Métral,“Electromagneticfieldcreatedbya
macroparticleinaninfinitellongandaxisymmetricmultilayer
beam pipe”, Rep. CERN-BE-2009-039, 2009.
[3]G. Skripka, R. Nagaoka, M. Klein, F. Cullinan, and P. F.
Tavares, ... | D:\Daily_ihep\Conferences\IPAC2026\WEP\WEP5091.pdf | 3 |
7ddcf378-657f-43e6-a7b2-7a02094ca8ae | tor”,Phys. Rev. Accel. Beams, vol. 21, no. 2, p. 024401, Feb.
2018.doi:10.1103/PhysRevAccelBeams.21.024401
[6]G. Stupakov and D. Zhou, “Transverse wakefields due to
asymmetric protrusions into a vacuum chamber”,Nucl. In-
strum. Methods Phys. Res., Sect. A, vol. 764, pp. 378–382,
Nov. 2014.doi:10.1016/j.nima.2014.08.006... | D:\Daily_ihep\Conferences\IPAC2026\WEP\WEP5091.pdf | 3 |
949d7ddc-1109-427f-b48a-ed58e9fc6ead | Jul. 2006.[10]R. Nagaokaet al., “Beam Instability Observations and Anal-
ysis at SOLEIL”, inProc. PAC’07, Albuquerque, NM, USA,
paper WEOBC01, pp. 2019–2021, Aug. 2007.
[11]S.Thakur, “Beamcouplingimpedancestudy andvalidation
of instability models for SOLEIL”, Master thesis, Université
Paris-Saclay, 2025.
[12]R. L. Gluc... | D:\Daily_ihep\Conferences\IPAC2026\WEP\WEP5091.pdf | 3 |
0896c581-b276-45fc-90a6-0190c361c4a1 | Rev. ST Accel. Beams, vol. 9, no. 11, p. 114402, Nov. 2006.
doi:10.1103/PhysRevSTAB.9.114402
[15]A. Gamelin, W. Foosang, and R. Nagaoka, “mbtrack2, a Col-
lectiveEffectLibraryinPython”,inProc.IPAC’21,Camp-
inas, Brazil, May 2021, pp. 282–285.
doi:10.18429/JACoW-IPAC2021-MOPAB070
[16]A. Gamelin, W. Foosang, N. Yamamoto,... | D:\Daily_ihep\Conferences\IPAC2026\WEP\WEP5091.pdf | 3 |
4c421062-2ca2-43ee-8b57-da81c540bfc4 | ISBN: 978-3-95450-252-3 ISSN: 2673-5350 doi: 10.18429/JACoW-IPAC2026-WEP5091
MC5.D04: Beam Coupling Impedance Theory, Simulations, Measurements, Code Development 2477WEP: Poster session WEP5091
Content from this work may be used under the terms of the CC BY 4.0 licence (© 2026). Any distribution of this work must maint... | D:\Daily_ihep\Conferences\IPAC2026\WEP\WEP5091.pdf | 3 |
93908e2a-c1d0-4d95-8405-bbbe4bbe5b9b | DOUBLE RF SYSTEM DESIGN USING NORMAL CONDUCTING PASSIVE
HARMONIC CAVITY FOR SOLEIL II
A. Gamelin∗, M. Diop, V. Gubaidulin, P. Marchand, R. Nagaoka, F. Ribeiro, L. Zhao
Synchrotron SOLEIL, Saint-Aubin, France
Abstract
Doublerfsystemsarecriticalforachievingtheparame-
ters of fourth-generation synchroton light sources. Th... | D:\Daily_ihep\Conferences\IPAC2026\WEP\WEP5092.pdf | 0 |
08d85b31-cc44-4e90-b825-e0b217029854 | pected performances of the double rf system, using the opti-
mized normal conducting passive harmonic cavity parame-
ters, are presented.
INTRODUCTION
SOLEIL II [ 1–3], is a 4th-generation synchrotron light
source(4GLS)presentlyinconstructionphase. Likemost
4GLS, it will rely on a double rf system, composed of main
rf ... | D:\Daily_ihep\Conferences\IPAC2026\WEP\WEP5092.pdf | 0 |
4a455619-e63c-4ea1-b56d-862e5f9d9c67 | cavities,basedonacustomdesignmadeintheframeworkof
a collaboration with the ESRF [ 8,9], which operates on the
TM020mode,toachievelow 𝑅/𝑄andlargedampingoflower
andhigherordermodes(LOMandHOM).Thesecavities
are equipped with a coupling port, which will be used for
therf conditioningbeforetheinstallationinSOLEILII,and
ma... | D:\Daily_ihep\Conferences\IPAC2026\WEP\WEP5092.pdf | 0 |
60003bf4-ef42-46ba-a1c4-c7b6ec932c55 | ∗alexis.gamelin@synchrotron-soleil.frTable 1: SOLEIL II StorageRing Parameters
Parameter Value
Electron beam energy 𝐸0 2.75GeV
Natural emittance 84pm
Circumference 𝐿 353.97m
Revolution frequency 𝑓0 846.9kHz
Rf frequency 𝑓rf 352.3MHz
Harmonic number ℎ 416
Momentum compaction factor 𝛼𝑐 1.057×10−4
Energy loss per tu... | D:\Daily_ihep\Conferences\IPAC2026\WEP\WEP5092.pdf | 0 |
e4b31f1d-0874-4413-847f-41cb7ae4f4f2 | ALBuMSsolvesasystemofcoupledHaïssinskiequations[ 13]
andcheckswhethertheresultingequilibriumisstableornot
for various instabilities.
Figure1showsthepredictedinstabilitiesforSOLEILII
storageringwith2passiveHC.Foreachpairofbeamcurrent
𝐼0and HC tuning angle 𝜓2in the plot, either the ALBuMS
algorithm(left)or mbtrack2 tra... | D:\Daily_ihep\Conferences\IPAC2026\WEP\WEP5092.pdf | 0 |
aa973825-52e2-4f11-8195-5dd915196765 | bility(FMCI)[ 14],correspondingtothecouplingbetween
the dipole ( 𝑚 = 1) and quadrupole ( 𝑚 = 2) azimuthal
modes, is shown in red. Both the periodic transient beam
loading(PTBL)instability[ 15,16]andpureCBIofcoupled-
bunch mode number 𝑙 = 1are shown in green. Overall,
the agreement between the predicted instability u... | D:\Daily_ihep\Conferences\IPAC2026\WEP\WEP5092.pdf | 0 |
b81e45c3-c712-4b6d-9708-73d0d8f170f6 | Figure 1: Instabilities predicted for the SOLEIL II storage ring, with ALBuMS(left) and with mbtrack2 (right). A HOM is
included with 𝑓HOM= 1.7GHz,𝑄HOM= 670and𝑅𝑠HOM= 8.8kΩ. Using 2 HC, i.e. (𝑅/𝑄)2= 60Ω. Figurefrom [ 7].
dealt with by using a direct rf feedback [ 6,17] lowering the
MC effective impedance seen by t... | D:\Daily_ihep\Conferences\IPAC2026\WEP\WEP5092.pdf | 1 |
f80ba156-68e1-4847-a329-72c8267da6f3 | 𝑅[19]. Figure 2shows the maximum 𝑅achievable with
a stable beam in the ((𝑅/𝑄) 2,𝑄02)parameter space for a
given beam current of 𝐼0= 500mA.
Figure 2: Maximum Touschek lifetime ratio 𝑅achievable
with a stable beam. (𝑅/𝑄)2is varied for different values of
𝑄02for a beam current of 𝐼0=500mA. Figure from [ 7].
As ... | D:\Daily_ihep\Conferences\IPAC2026\WEP\WEP5092.pdf | 1 |
6d320ae5-aa13-42da-8496-fd181bef0cbf | ForSOLEILII,theHCneedstobeusedfrom 200mAup
to500mAtocoveroperationsin32bunchmodeanduniform
fillingmode. Using ALBuMS,wewereabletospecifyoptimal
(𝑅/𝑄)2and𝑄02values for cavity design. The choice was
madetouse2or3HCof (𝑅/𝑄)2=30Ωeachwith 𝑄02=
31×103, to be able to vary the total (𝑅/𝑄)2from60Ω to
90Ω. It is close to... | D:\Daily_ihep\Conferences\IPAC2026\WEP\WEP5092.pdf | 1 |
b2242016-d85d-4ead-af70-e595d79b02e1 | impedancemodel[ 20],HOMsfromthemaincavitiesand
IBS[21]. TheMCmodelincludesaproportional-integral
loop to converge toward the voltage and phase setpoints and
a direct rf feedback, which helps against the FMCI.
Foruniform fillingcases at 500mA,the resultsfrom Ta-
ble2align closely with the ones from ALBuMS, like the left... | D:\Daily_ihep\Conferences\IPAC2026\WEP\WEP5092.pdf | 1 |
96eddd61-d61a-4caf-8d66-d0c70d72cb8e | ISBN: 978-3-95450-252-3 ISSN: 2673-5350 doi: 10.18429/JACoW-IPAC2026-WEP5092
MC5.D05: Coherent and Incoherent Instabilities Theory, Simulations, Code Development 2479WEP: Poster session WEP5092
Content from this work may be used under the terms of the CC BY 4.0 licence (© 2026). Any distribution of this work must maint... | D:\Daily_ihep\Conferences\IPAC2026\WEP\WEP5092.pdf | 1 |
36e223c1-0a80-478d-a8fc-707546c8dfd6 | Table 2: Best performances achieved at equilibrium without instabilities while scanning the HC tuning angle 𝜓2. Tracking
withmbtrack2 includes direct rf feedback, PI feedback, impedance model, HOMs and IBS. The transverse emittance ratio
is set at 30% using white noise excitation.
HC Beam HC tuning RMS bunch Touschek ... | D:\Daily_ihep\Conferences\IPAC2026\WEP\WEP5092.pdf | 2 |
a7dbbff3-43e9-4fe0-abca-806e697f6262 | 3HCs, thetotalR/QistoohighandtriggersthePTBLin-
stability largely before reaching optimal bunch lengthening.
With2HCsplusoneparked,thereisaminorperformance
reduction due to the R/Q of the parked cavity.
Forthe32bunchmodeat 200mA,itwasexpectedfrom
semianalytical computations that the 3 HC case would be
more favorable be... | D:\Daily_ihep\Conferences\IPAC2026\WEP\WEP5092.pdf | 2 |
2ce7ebc5-1a6a-49cb-a3f1-593e691c928f | from optimal bunch lengthening, can be explained by the
combination of two single bunch effects: the reduced bunch
length from HOM capacitive impedance [ 22] and the strong
coherent tune shift from broad band impedance. The first
effect reduces bunch length, which is known to lower the
PTBL threshold [ 16] and the seco... | D:\Daily_ihep\Conferences\IPAC2026\WEP\WEP5092.pdf | 2 |
27951e3f-87d5-42ae-9d0c-aa4abc705be5 | performance.
The modeling of LLRF feedbacks in trackingsimulation
must be improved to better match the logic implemented in
theSOLEILIIhardwaresystem. Inparticular,toquantify
therisk ofself-triggeringthedipole-quadrupoleinstability
at high gain [ 7], and to evaluate the need for alternative
mitigationagainsttheFMCI.Exp... | D:\Daily_ihep\Conferences\IPAC2026\WEP\WEP5092.pdf | 2 |
a395ad25-dfbe-49c0-8491-b8c9e79d40be | system. A dedicated study of these instabilities and the
associated feedback requirements should be done.
CONCLUSION
TheSOLEILIIdoublerfsystemhasbeenoptimizedus-
ingacombinationofthesemianalyticalsolver ALBuMSfor
fast multi-dimensional scans and the multibunch tracking
codembtrack2 for detailed verification. This appro... | D:\Daily_ihep\Conferences\IPAC2026\WEP\WEP5092.pdf | 2 |
04ff339a-038a-43fe-9ef7-edb93c4033b3 | in 32 bunch mode. The 32 bunch case also illustrates the
importance of single-bunch effects, which can impact the
PTBL threshold significantly at high charge per bunch.
REFERENCES
[1]Synchrotron SOLEIL, “Conceptual Design Report - Syn-
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paper, Jul. 2021.
[2]A.NadjiandL... | D:\Daily_ihep\Conferences\IPAC2026\WEP\WEP5092.pdf | 2 |
b096c99e-103a-488f-a80c-76d8b031ce2c | Yamamoto, “Beam dynamics with a superconducting har-
monic cavity for the SOLEIL upgrade”, in Proc. IPAC’22 ,
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ISBN:... | D:\Daily_ihep\Conferences\IPAC2026\WEP\WEP5092.pdf | 2 |
e36e3846-dfa8-4488-9b99-d0f5e99aea90 | [5]A.Gamelin etal.,“Beamdynamicsusingsuperconducting
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R. Nagaoka, “Stability survey of a double ... | D:\Daily_ihep\Conferences\IPAC2026\WEP\WEP5092.pdf | 3 |
fb13146e-6d00-444c-a0a6-2c381acb0b85 | [8]A. D’Elia, “4th harmonic cavities in TM020 for ESRF-EBS
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[10]A. Gamelin, W. Foosang, and R. Nagaoka, “mbtrack2, a col-
lectiveeffectlibraryinPython... | D:\Daily_ihep\Conferences\IPAC2026\WEP\WEP5092.pdf | 3 |
18856081-aea9-44ec-89f5-0c31b80285b5 | [13]J. Haïssinski, “Exact longitudinal equilibrium distribution
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[14]R.A.Bosch,K.J.Kleman,andJ.J.Bisognano,“Robinson
instabilities wit... | D:\Daily_ihep\Conferences\IPAC2026\WEP\WEP5092.pdf | 3 |
dc256173-8766-48e1-acf5-8efd15b47248 | loading effect with passive harmonic cavities in electron stor-
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[17]K. Akai, “Stability analysis of rf accelerating mode with
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c5f3e978-99d4-4b0f-87e9-cec760273e96 | on bunch lengthening”, Nucl. Instrum. Methods Phys. Res. A ,
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[23]M.B.Alves,“Theoreticalmodelsforlongitudinalcoupled-
bunchinstabilitiesdrivenbyharmoniccavitiesinelectronstor-
agerings”, Phys.Rev.Accel.Beams ,vol.28,no.3,p.0344... | D:\Daily_ihep\Conferences\IPAC2026\WEP\WEP5092.pdf | 3 |
4098d2fa-3b25-48e9-afe0-ac8c69b62a6b | MULTI-BUNCH LONGITUDINAL BEAM DYNAMICS IN THE
ELETTRA 2.0 STORAGE RING WITH A DOUBLE-RF SYSTEM
S. Dastan∗, S. Di Mitri, E. Karantzoulis, S. Krecic, M. Lonza, K. Manukyan
Elettra-Sincrotrone Trieste S.C.p.A., Trieste, Italy
Abstract
Wepresentasystematicmulti-bunchlongitudinalbeam
dynamics study for the Elettra 2.0 stora... | D:\Daily_ihep\Conferences\IPAC2026\WEP\WEP5096.pdf | 0 |
35506c43-6ff7-45bd-8405-88db36917bed | the longitudinal feedback. The analytical predictions are
benchmarked against multi-bunch tracking in Elegant. In
parallel, we optimise the double-RF parameters for both
uniformandnon-uniformfillingsusingmbtrack2tracking
with the ALBuMS (Algorithm for Longitudinal Multibunch
Beam Stability) algorithm. Forthe operationa... | D:\Daily_ihep\Conferences\IPAC2026\WEP\WEP5096.pdf | 0 |
f922cdb0-4da6-4101-b7d5-4cbd757c9b4e | groupconsistsofHOM-drivencoupled-bunchinstabilities.
These are driven by higher-order modes of the main RF cav-
ityand areanalyzedusing HOMparameters obtainedfrom
electromagnetic simulations. This framework is particularly
relevant for bunch-lengthened beams in nonlinear or near-
quartic longitudinal potentials, where ... | D:\Daily_ihep\Conferences\IPAC2026\WEP\WEP5096.pdf | 0 |
2b129ff8-ae3d-4dee-ac5e-53b5e8498b95 | mechanisms can dominate different regions of parameter
space and strongly constrain the accessible harmonic-cavity
operating window. The purpose of this paper is therefore
to combine these two levels of analysis: first, the study of
HOM-driven coupled-bunch growth rates and their reduc-
tionviaLandaudampinginthedouble-... | D:\Daily_ihep\Conferences\IPAC2026\WEP\WEP5096.pdf | 0 |
c006c5d7-5edf-426b-b9af-e087b7e8f4a2 | for Elettra 2.0 [ 3]. To identify the modes that can drive
longitudinalcoupled-bunchinstabilities,aroughimpedance
threshold criterion is applied [ 4]:
𝑍thresh
∥=1
𝑁𝑐⋅1
𝑓HOM⋅2𝐸0𝑄𝑠
𝐼0𝜏𝑠(1)
Here,𝑁𝑐is the number of cavities, 𝑓HOMis the HOM fre-
quency,𝐸0isthebeamenergy, 𝑄𝑠isthesynchrotrontune, 𝐼0
isthetota... | D:\Daily_ihep\Conferences\IPAC2026\WEP\WEP5096.pdf | 0 |
e2b6e3a7-4eca-4f86-8f0d-9ba926736ead | This ensures that each HOM effectively couples to a sin-
glerevolutionharmonic, withthestrongestinstabilitynear
𝑓HOM≈ 𝑁𝑓rev. After filtering, 69 HOMs are retained.
Growth Rate Analysis
ThegrowthratesofthefilteredHOMsareevaluatedusing
two approaches.
SHO model: The simple harmonic oscillator (SHO)
modelassumes arigid... | D:\Daily_ihep\Conferences\IPAC2026\WEP\WEP5096.pdf | 0 |
ee3779af-4747-468a-916a-c00d7b453bd8 | ISBN: 978-3-95450-252-3 ISSN: 2673-5350 doi: 10.18429/JACoW-IPAC2026-WEP5096
2482 MC5.D05: Coherent and Incoherent Instabilities Theory, Simulations, Code DevelopmentWEP5096 WEP: Poster session
Content from this work may be used under the terms of the CC BY 4.0 licence (© 2026). Any distribution of this work must maint... | D:\Daily_ihep\Conferences\IPAC2026\WEP\WEP5096.pdf | 0 |
a11e9c68-5362-4e22-8851-58993b7862f4 | 0 1 2 3 4 5 6 7
Frequency [GHz]050100150200250300350400Impedance [k ]Longitudinal Impedance vs Threshold
PEC HOM
PMC HOM
Threshold (No 3HC)
Threshold (With 3HC)Figure 1: Longitudinal impedance of HOMs compared to
the instability threshold. PEC (perfect electric conductor)
andPMC(perfectmagneticconductor)denotethebounda... | D:\Daily_ihep\Conferences\IPAC2026\WEP\WEP5096.pdf | 1 |
a911ed3f-9af1-4874-9b11-e10160352a68 | thedetuningdirection). UnliketheSHOmodel,theresponse
is asymmetric around resonance.
Tracking Validation
Theanalyticalpredictionsarebenchmarkedagainstmulti-
bunchtrackingsimulationsperformedwithElegant[ 6]. The
simulationsarecarriedoutassuminguniformfillingwith432
bunches,eachrepresentedby 105macroparticles. Thetrack-
... | D:\Daily_ihep\Conferences\IPAC2026\WEP\WEP5096.pdf | 1 |
dcfecb48-c0ba-4be7-865b-2374bb26afc0 | order. Thethird-harmoniccavityismodeledasanactiveRF
-3 -2 -1 0 1 2 3
= (2Q/HOM)(HOM-N0)-3000-2000-10000100020003000400050006000growth rate [1/s]Figure3: GrowthratesofHOMsasafunctionofnormalized
detuning ̄ 𝜔including Landau damping (HHC model). Each
curve corresponds to a different HOM.
0 2000 4000 6000 8000 10000 120... | D:\Daily_ihep\Conferences\IPAC2026\WEP\WEP5096.pdf | 1 |
44f3a680-5070-46d7-ab41-7d8e516a1de0 | amplitude in logarithmic scale, from whichthe exponential
growth rate is extracted via linear fitting.
system. Thebeamistrackedfor80000turns,withagradual
ramp-up of the impedance over the first 5000 turns to avoid
artificial transients.
ForthisHOM,the SHOmodelpredicts agrowthrateof
1710s−1,whiletheHHCmodelpredictsaredu... | D:\Daily_ihep\Conferences\IPAC2026\WEP\WEP5096.pdf | 1 |
d9e74156-57fe-49d0-b89c-ea1f86984b53 | results, shown in Fig. 4, confirm that the instability initially
followstheSHObehaviorandthentransitionstotheHHC
regime,showinggoodagreementbetweenanalyticalmodels
and tracking simulations.17th International Particle Accelerator Conference, Deauville, France JACoW Publishing
ISBN: 978-3-95450-252-3 ISSN: 2673-5350 doi:... | D:\Daily_ihep\Conferences\IPAC2026\WEP\WEP5096.pdf | 1 |
d7afb623-29b7-451d-9f12-fc5dd5ddded6 | 89.970 89.975 89.980 89.985 89.990 89.995 90.000
Detuning [kHz]100150200250300350400Current [mA]Uniform_F illing
0.10.2
0.30.4
0.5
0.60.7
0.80.9
1.01.01.01.01.01.0
1.11.11.11.1
1.2
1.31.31.31.4
Dipole Robinson instability
Quadrupole Robinson instability
F ast mode -coupling instability
PTBL
Not converged
0.00.20.40.60.... | D:\Daily_ihep\Conferences\IPAC2026\WEP\WEP5096.pdf | 2 |
e3c03537-0fd8-4986-9cf7-58733fc64278 | ble. The cavity detuning is expressed in terms of the tuning
angle𝜓, defined from the cavityvoltageand beam loading
conditions [ 1]:
tan𝜓 = 𝑄𝐿(𝜔𝑟
𝜈𝜔rf−𝜈𝜔rf
𝜔𝑟) (2)
where𝜈istheharmonicnumberofthecavity. Theresults
show that the dominant instability in this configuration is
thedipoleRobinsoninstability. Byse... | D:\Daily_ihep\Conferences\IPAC2026\WEP\WEP5096.pdf | 2 |
ff188457-edb1-4ea6-b2c3-016e969ac9bf | 89.97∘–89.999∘, corresponding to 7–195 kHz. The re-
sults show that for detuning values between 7 and 71 kHz
(89.97∘–89.997∘), the beam is strongly affected by periodic
transientbeamloading(PTBL)instability,asshowninFig. 5.
AsshowninFig. 6,thegrowthrateofthePTBLinstability
exceedsthelongitudinalfeedbackcapabilityofElet... | D:\Daily_ihep\Conferences\IPAC2026\WEP\WEP5096.pdf | 2 |
1b6b345f-7739-4988-bfa9-cd3a899b3a4e | ablyoverthefulldetuningrange. However,restrictingthe
analysistothesafeinterval(72–107kHz),astableregioncan
stillbeidentified. In thiscase, theoptimaldetuningrange
is found between 80 and 85 kHz, where: 𝜁 = 0.85 –0.90,
Bunchlength: 15.2–16psandTouscheklifetimeimprove-
ment:×2.4–2.5.
Tracking Benchmark with mbtrack2
The... | D:\Daily_ihep\Conferences\IPAC2026\WEP\WEP5096.pdf | 2 |
0875bbc4-cd8a-491b-9f30-eac76a28e39b | condition.
CONCLUSION
Amulti-bunchlongitudinal beamdynamics studyof the
Elettra 2.0 double-RF system has been presented. The in-
clusion of Landau damping significantly reduces both the
numberofcriticalHOMsandtherequireddetuning,from
about±69kHzin the SHO model to about −46kHz(or
∼ 30kHz) in the HHC model. Tracking sim... | D:\Daily_ihep\Conferences\IPAC2026\WEP\WEP5096.pdf | 2 |
ce36039f-26df-4685-babb-4bf342edb2c3 | ISBN: 978-3-95450-252-3 ISSN: 2673-5350 doi: 10.18429/JACoW-IPAC2026-WEP5096
2484 MC5.D05: Coherent and Incoherent Instabilities Theory, Simulations, Code DevelopmentWEP5096 WEP: Poster session
Content from this work may be used under the terms of the CC BY 4.0 licence (© 2026). Any distribution of this work must maint... | D:\Daily_ihep\Conferences\IPAC2026\WEP\WEP5096.pdf | 2 |
224ec0e3-33dd-4930-8bfe-9f95b73cf49b | REFERENCES
[1]A. Gamelin et al., “Algorithm for longitudinal multibunch
beam stability (ALBuMS)”, Phys. Rev. Accel. Beams, vol. 28,
p. 054401, 2025.
doi:1/zero.alt4.11/zero.alt43/PhysRevAccelBeams.28./zero.alt4544/zero.alt41
[2]N. Shafqat and C. Pasotti, “Elettra cavity HOM and dedicated
dampers design”, presented at t... | D:\Daily_ihep\Conferences\IPAC2026\WEP\WEP5096.pdf | 3 |
97180cfc-2560-47a8-9652-08507690ef4c | pp. 846–848.
[5]R. R. Lindberg, “Theory of coupled-bunch longitudinal insta-
bilitiesinastorageringforarbitraryRFpotentials”,Phys.Rev.
Accel. Beams, vol. 21, p. 124402, 2018.
doi:1/zero.alt4.11/zero.alt43/PhysRevAccelBeams.21.1244/zero.alt42
[6]M. Borland, “Elegant: A flexible SDDS-compliant code for
acceleratorsimulat... | D:\Daily_ihep\Conferences\IPAC2026\WEP\WEP5096.pdf | 3 |
43f0564c-bad4-4e5f-b997-e84640e1a180 | ISBN: 978-3-95450-252-3 ISSN: 2673-5350 doi: 10.18429/JACoW-IPAC2026-WEP5096
MC5.D05: Coherent and Incoherent Instabilities Theory, Simulations, Code Development 2485WEP: Poster session WEP5096
Content from this work may be used under the terms of the CC BY 4.0 licence (© 2026). Any distribution of this work must maint... | D:\Daily_ihep\Conferences\IPAC2026\WEP\WEP5096.pdf | 3 |
99f7e195-9cbc-46b6-81dc-f733d5d42fb7 | RECENT PROGRESS IN IMPEDANCE MITIGATION
FOR HL-LHC BEAM INSTRUMENTATION
M. Neroni∗, W. Andreazza, R. Calaga, W. Hofle, I. Karpov, G. Khatri, M. Krupa,
L. Margerison, M. McLean, C. Pasquino, H. Pommerenke, J. Storey, C. Vollinger
CERN, Geneva, Switzerland
Abstract
IntheHigh-LuminosityLHC(HL-LHC)era,increased
beam intens... | D:\Daily_ihep\Conferences\IPAC2026\WEP\WEP5098.pdf | 0 |
ecaecc69-6669-4475-a34d-977d47dc350b | impedancemitigationstrategythatreducesbeam-induced
heating at high intensities, maintaining device functionality
and beam stability in the HL-LHC era.
INTRODUCTION
In preparation for the High-Luminosity LHC (HL-LHC)
upgrade, the request for increased beam intensities, while
maintaining beam quality poses stringent cons... | D:\Daily_ihep\Conferences\IPAC2026\WEP\WEP5098.pdf | 0 |
70a70dbc-d062-4b41-bb86-eb8a3334ea43 | and𝑁beamaccounting forthe total number of bunches. The
Fouriertransformofthetotalbeamdistributionisthenor-
malized beam spectrum, Λ(𝜔rev).
Atthesametime,itmustbeensuredthatanyadditional
sourceofbeamcouplingimpedancedoesnotsignificantly
impact the beam stability threshold. In the longitudinal
plane, it was observed th... | D:\Daily_ihep\Conferences\IPAC2026\WEP\WEP5098.pdf | 0 |
ba780dd5-e604-4995-9d89-74c845410de4 | priortoinstallation. Twomitigationexamplesarepresented:
∗michela.neroni@cern.ch
Beam
400 mm
120 mm
40 mm
46.5 mm
direction
1163 mm(a)
400 mm
120 mm
40 mm
45.5 mm
1163 mm
90 mm
(b)
Figure1: Initial(a)andfinal(b)geometryofhigh-bandwidth
pick-upsusedforintra-bunchmeasurementsandforthecrab
cavity noise feedback and low-lev... | D:\Daily_ihep\Conferences\IPAC2026\WEP\WEP5098.pdf | 0 |
a4e48d20-ac50-4b98-95e5-9ee727cc33b1 | sists of400mmlong striplines for intra-bunch measure-
ments [3], followed by button pick-ups and 120mmlong
striplinesdedicatedtothelow-levelRFsystemcrabcavity
noisefeedback[ 4]. Theinnersurfaceofthestainless-steel
beam pipe has a 10𝜇𝑚copper coating to reduce resistive
wall impedance. Below 50MHz, even with the copper... | D:\Daily_ihep\Conferences\IPAC2026\WEP\WEP5098.pdf | 0 |
c450d371-c5d7-430b-8c6b-52191e2ac4ca | wereassumedtobeimpedancematched,asintherealsys-
tem, to prevent undesired reflections within the structure.
Figure2shows the resulting longitudinal impedance for the
configurationillustratedinFig. 1a. Anoscillatorybehaviour
isobservedupto 2GHz,associatedwiththestriplinelength17th International Particle Accelerator Conf... | D:\Daily_ihep\Conferences\IPAC2026\WEP\WEP5098.pdf | 0 |
7b31a28a-ecbe-4e99-9b34-6c4abdbdacd5 | up to 950 ΩFigure 2: Longitudinal impedance from 1 MHz to 3.5 GHz:
in blue for initial design of high-bandwidth BPMs and in
red for the final design.
and consistent with the analytical expression reported in
Ref. [6].
Above2GHz, a narrowband resonance is observed at
2.6GHzwith a shunt impedance of approximately 950Ω.
T... | D:\Daily_ihep\Conferences\IPAC2026\WEP\WEP5098.pdf | 1 |
97e1db97-c21b-44ac-8c46-fcc637e6c43b | geometry demonstrate a significant impedance reduction
(Fig.2, red). The resonance at 2.6GHzis completely sup-
pressedandthemaximumoftheimpedancemagnitudeisre-
duced to about 105Ωat2.71GHz . Considering four BPMs
per beam, the updated design contributes to a total effective
Im(𝑍/𝑛)of0.05mΩthatislowercomparedto 0.07mΩ... | D:\Daily_ihep\Conferences\IPAC2026\WEP\WEP5098.pdf | 1 |
ab414bce-5bf8-48a5-81b8-4ac872b742ec | 2.6GHz. A trapped mode is observed in the beam pipe
regionwheretheradiustransitionsfrom 40mmtoalarger
value of 46.5mm, and then backto 40mm.
Ceramic
Steel cathode
Fused
silica
tube
HV
feedthrough
Detector region under RF shield
holders
≈87 mm
Beam
directionFigure 4: BGI monitor geometry: initial design (top) and
impeda... | D:\Daily_ihep\Conferences\IPAC2026\WEP\WEP5098.pdf | 1 |
675b50c5-fc96-4947-97af-f5760998eae2 | it wascrucial to assess the impact of the high-voltage(HV)
feedthrough. Figure 5shows the real part of the impedance
upto2GHz,comparingidealmatchingatthefeedthrough
port (blue), a short circuit (green), and an open circuit (yel-
low). Withoutproperimpedancematching,internalreflec-
tions introduce undesired resonances, ... | D:\Daily_ihep\Conferences\IPAC2026\WEP\WEP5098.pdf | 1 |
2637ad6b-3c8c-476d-8534-032eda0db508 | in Fig.6, assuming a matched HV feedthrough. Two broad-
band (𝑄 ≈ 1) contributions can be identified at 169MHz
and at882MHz. Additional narrowband resonances are
0.0 0.5 1.0 1.5 2.0
Frequency [GHz]02505007501000Real(Z) [Ω]impedance matching
short circuit
open circuit
Figure 5: Real part of the longitudinal beam coupli... | D:\Daily_ihep\Conferences\IPAC2026\WEP\WEP5098.pdf | 1 |
bcb72df0-3fb1-42fc-a291-458aaf2a8651 | Table 1: Resonant frequency, quality factor and shunt
impedance for narrowband resonances in the BGI before
and after mitigation.
Before After
𝑓r[GHz]𝑓r[GHz]𝑓r[GHz] 𝑄0𝑄0𝑄0𝑅s[Ω]𝑅s[Ω]𝑅s[Ω]𝑓r[GHz]𝑓r[GHz]𝑓r[GHz] 𝑄0𝑄0𝑄0𝑅s[Ω]𝑅s[Ω]𝑅s[Ω]
0.808 328 38 0.847 120 2
1.516 56 21.6 Broadband contribution left
1.744... | D:\Daily_ihep\Conferences\IPAC2026\WEP\WEP5098.pdf | 2 |
0a848044-2258-4bfd-8542-37259eb8cbdd | about113W. A powerloss of 66Woriginatesfrom broad-
bandcontributionsbelow 500MHz . Thepowerlossdistribu-
tionshowsthat98%ofthispowerispassingthroughtheHV
feedthroughport. Consequently,aresistiveloadmatching
thecharacteristicimpedanceoftheHVfeedthroughmustbe
incorporatedtodissipatetheextractedpower. Theresidual
power lo... | D:\Daily_ihep\Conferences\IPAC2026\WEP\WEP5098.pdf | 2 |
086f5496-77ae-488d-b627-704d74474cdf | theintroductionofalargeropeningasindicatedinthered
circle in the geometry in Fig. 4(bottom). This modification
effectivelysuppressesthebroadbandimpedanceat 882MHz
aswellastheresonancesat 1.5GHzand1.85GHz . Electric
field monitors at the two major impedance peaks, 808MHz
and1.91GHz , are shown in Fig. 7. They indicated ... | D:\Daily_ihep\Conferences\IPAC2026\WEP\WEP5098.pdf | 2 |
0e245740-2a45-4c46-9c18-d2c197391d42 | tom).
hancedbytheceramicholders. Thiseffectcanbeinterpreted
as a parallel plate capacitor to ground, with a capacitance
of approximately 𝐶 = (𝜀𝑅𝜀0𝐴)/𝑑. The volume of the ce-
ramicholders(macor, 𝜀𝑅= 6)wasreducedfrom 8.4𝑐𝑚3to
2.2𝑐𝑚3with the aim of obtaining a decrease of the equiv-
alent𝜀𝑅inthegap. Addition... | D:\Daily_ihep\Conferences\IPAC2026\WEP\WEP5098.pdf | 2 |
e9ffc6f5-0a12-4a05-98c1-483000e846c0 | andthemaximumtotalpowerlossdecreasesto 78W. The
proposed mitigation measures are currently under consider-
ation, with a major focus on the matching network for the
HV feedthrough.
CONCLUSION
Theresultspresentedhighlightthatimpedancemitigation
is essential to reduce beam-induced heating and to ensure
componentintegrity... | D:\Daily_ihep\Conferences\IPAC2026\WEP\WEP5098.pdf | 2 |
370b2b84-b014-4a75-b4b0-bbc02707d7ca | affecting the primary functionality of the device. A beam
stability assessment for the HL-LHC BGI will follow based
on the finalised design. Impedance simulations will be vali-
datedbyRFmeasurements beforeinstallationwiththe aim
of benchmarking the electromagnetic model.17th International Particle Accelerator Conferenc... | D:\Daily_ihep\Conferences\IPAC2026\WEP\WEP5098.pdf | 2 |
b1a85814-da75-46c2-8d72-238cdf9d4e44 | ACKNOWLEDGMENTS
TheauthorswouldliketoexpresstheirgratitudetoHeiko
Damerau for the fruitful discussions.
REFERENCES
[1]M. Furman, H. Lee, and B. Zotter, “Energy Loss of Bunched
Beams in RF Cavities”, Lawrence Berkeley Laboratory, CA,
USA, Rep. SSC-086, Aug. 1986.
[2]I.KarpovandE.Shaposhnikova,“Generalizedthresholdof
lon... | D:\Daily_ihep\Conferences\IPAC2026\WEP\WEP5098.pdf | 3 |
bc2c3a98-a769-40ff-a76b-1ceeb1086a5e | [5]CST Studio Suite, https://www.3ds.com/products-
services/simulia/products/cst-studio-suite/[6]K.Y.Ng,“ImpedancesofStriplineBeamPositionMonitors”,
Part. Accel. , vol. 23, pp. 93–102, 1988.
[7]C.Pasquino etal.,“HL-LHCBGImechanicaldesign:integra-
tion, impedance and vacuum aspects”, presented at IPAC’26,
Deauville,Fran... | D:\Daily_ihep\Conferences\IPAC2026\WEP\WEP5098.pdf | 3 |
3bb80997-d3e3-4849-a750-b0c1e190062e | vant, and C. Zannini, “A Python Package to Compute Beam-
Induced Heating in Particle Accelerators and Applications”,
inProc. HB’23 , Geneva, Switzerland, Oct. 2023, pp. 611–
614. doi:1/zero.alt4.18429/JACoW-HB2/zero.alt423-THBP5217th International Particle Accelerator Conference, Deauville, France JACoW Publishing
ISBN... | D:\Daily_ihep\Conferences\IPAC2026\WEP\WEP5098.pdf | 3 |
321c4c44-1b43-48ab-9213-2356a05906c6 | ADVANCED BEAM COUPLING IMPEDANCE MODELING FOR LHC AND
HL-LHC APPLICATIONS∗
C. Zannini†, C. Antuono, E. de la Fuente Garcia, G. Rumolo, B. Salvant, L. Sito, J. Sonpar
CERN, Geneva, Switzerland
Abstract
Accuratebeamcouplingimpedancemodelingisessential
for predicting collective effects and ensuring stable high-
intensity ... | D:\Daily_ihep\Conferences\IPAC2026\WEP\WEP5101.pdf | 0 |
8d44b4be-6224-4813-bf56-d36c15765392 | operation. In this work, we present recent advancements
in high-fidelity impedance modeling and demonstrate their
relevance through representative case studies in the LHC.
Theseexamplesshowhowimprovedmodeling,combined
with beam-based diagnostics, providescritical input forop-
erationalstrategiesandsupportsinformeddesig... | D:\Daily_ihep\Conferences\IPAC2026\WEP\WEP5101.pdf | 0 |
489c8209-b3dd-4103-8f03-fd81eaa45987 | loadsandmechanicalstressescaninduceprogressivegeo-
metricchanges,suchaslossofelectricalcontactordeforma-
tionofshieldingstructures,leadingto adynamicevolution
of the impedance during operation.
These observations motivate the development of high-
fidelitymodelingapproachescapableofcapturingbothde-
tailedgeometricalfeat... | D:\Daily_ihep\Conferences\IPAC2026\WEP\WEP5101.pdf | 0 |
5b9cc2a9-212e-4d15-8bf8-76112420acbb | thefailure. Beam-inducedlocalizedpowerdepositiononthe
∗Researchsupported bythe HL-LHC project
†carlo.zannini@cern.ch
Figure 1: Example of spring contact geometry used in
impedancesimulationsforanID212mm module. Thetop-
left picture shows the transition tube, contact fingers, and
the spring ensuring electrical contact b... | D:\Daily_ihep\Conferences\IPAC2026\WEP\WEP5101.pdf | 0 |
16914972-7db8-4fa6-99d6-e5378b7d722e | metric distribution of the fingers, which led to the observed
localized heating. The estimated power levels were found
to be consistent with the observed failure in the presence of
degraded fingercontact, explainingwhythe issue occurred
onlyinalimitednumberofmodules. Figure 2illustratesthe
localizedheating predictedbye... | D:\Daily_ihep\Conferences\IPAC2026\WEP\WEP5101.pdf | 0 |
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