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640bbb34-e4c8-4604-9927-18633ddf9134 | 𝐸0is the electron energy, and ℎis the harmonic number.
By setting the first and second derivatives of the total
cavityvoltageto zero, the well-known optimal-lengthening
condition is obtained [4]:
sin(𝜑1,𝑓𝑝) =𝑛2
𝑛2−1𝑈0
𝑒𝑉1, (3)
𝑘𝑓𝑝=√1
𝑛2−1
𝑛2−1(𝑈0
𝑒𝑉1)2
, (4)
tan(𝜑𝑛,𝑓𝑝) = −𝑛𝑈0
𝑒𝑉11
√(𝑛2−1)2−(𝑛... | d:\Daily_ihep\Weekly Progress Report\20260425\110_SAP2025\THP - Poster Session_ THP\THP24.pdf | 0 |
a1a48028-65d7-4b71-a784-6affe1bc4b86 | where𝜎𝛿istheRMSenergyspread,and 𝑈0theenergyloss
per turn.
The normalized equilibrium bunch distribution can be
obtained from the Haïssinski equation:
𝜌(𝜏) =𝑒ΦRF(𝜏)
∫+∞
−∞𝑒ΦRF(𝜏)𝑑𝜏. (7)
ThemainpurposeofemployingHCstolengthenbunches
istoimprovetheTouschekbeamlifetime.Thisimprovement
is typically quantified usi... | d:\Daily_ihep\Weekly Progress Report\20260425\110_SAP2025\THP - Poster Session_ THP\THP24.pdf | 1 |
7d38975a-f0e2-4109-8c86-2e4ed3e546e3 | |𝛾1| = 0.
For the subsequent analysis, we introduce two scaling
factors of 𝐾𝑉and𝐾𝜑to parameterize the HC settings:
𝑉𝑛= 𝐾𝑉⋅𝑉𝑛,fp, 𝜑𝑛= 𝐾𝜑⋅𝜑𝑛,fp,(10)
where𝑉𝑛,fpis the voltage amplitude under the optimal-
lengthening condition. Following the theoretical framework
in Ref. [6], we adopt the constraint 𝐾𝑉... | d:\Daily_ihep\Weekly Progress Report\20260425\110_SAP2025\THP - Poster Session_ THP\THP24.pdf | 1 |
98862aa9-d08d-4d52-a5da-b468a3b6144f | rapidconvergencetothe globalminimum withproveneffi-
ciency [7].
The optimization problem is formally stated as:
min𝐾𝜑|𝛾1(𝐾𝑉,𝐾𝜑)|, (11)
subject to:
ℒ(𝐾𝑉,𝐾𝜑) = ℒtarget, (12)
𝐾𝜑∈ [0.6(2−𝐾𝑉), 1.2(2−𝐾𝑉)]. (13)
Figure 1: (a) MC voltage as a function of momentum accep-
tance. (b) Bunch lengthening factor ℒver... | d:\Daily_ihep\Weekly Progress Report\20260425\110_SAP2025\THP - Poster Session_ THP\THP24.pdf | 1 |
5bbf6f7f-9e67-4891-ab14-a9c892a21411 | ofmomentumacceptance,computedfromEq.(2).ForHLS-
III, a minimum MCvoltageof 374kVis neededto achieve
amomentumacceptanceof 3.0%.Figure1(b)presents ℒ
as a function of the HC voltage scaling factor, as defined
in Eq. (10). The ℒincreases monotonically with the HC
voltage.
For the double-RF system, the parameter setting fo... | d:\Daily_ihep\Weekly Progress Report\20260425\110_SAP2025\THP - Poster Session_ THP\THP24.pdf | 1 |
5f086eb2-a12e-4373-a2f2-4316b9887eaa | Figure 3: HC voltage and Touschek lifetime improvement
factorℛversusℒ.
lengthening factor of 2-7 can be obtained, as also shownin
Fig. 2.
Figure 3 shows the Touschek lifetime improvement factor
ℛand the HC voltage as functions of ℒ. The improvement
factorreachesitsmaximumvalueof4.82atalengthening
factor of 5, correspon... | d:\Daily_ihep\Weekly Progress Report\20260425\110_SAP2025\THP - Poster Session_ THP\THP24.pdf | 2 |
4fc9a0d7-6643-4308-b015-d25e6ddeeb47 | creasesbuteventuallyreachesamaximum,indicatingthat
moderate over-lengthening can further improve beam life-
time. Furthermore, for a given ℒ, a higher RF frequency
(500MHz)demandsagreaterHCvoltagethanalowerfre-
quency (204MHz). Additionally, for a given frequency, a
lower harmonic number corresponds to a higher voltage... | d:\Daily_ihep\Weekly Progress Report\20260425\110_SAP2025\THP - Poster Session_ THP\THP24.pdf | 2 |
b1199c17-3a98-42bf-a11c-c95b5cde46db | below200kVandtheoperatingfrequenciesdonotexceed
1GHz.
For the500MHz option, referring to existing cavities,
suchasthe 500MHz EU-HOMdampedcavityattheALBA
light source [8], typically two MCs are required. For the
HCdesign,atleast 435kVand290kVarenecessaryforthe
cases of𝑛 = 2and𝑛 = 3, respectively. In these cases, the
F... | d:\Daily_ihep\Weekly Progress Report\20260425\110_SAP2025\THP - Poster Session_ THP\THP24.pdf | 2 |
a7c5c7cf-8577-4955-afec-0e85307bb078 | five RF configurations: 204MHz with 2nd–4th HCs, and
500MHz with 2nd–3rd HCs. Using a golden section search
to optimize bunch symmetry, we determined the required
cavityparametersforeachbunchlengtheningfactor ℒ.The
resultsrevealaconsistentincreaseintherequiredHCvoltage
withℒ,whilethelifetimeimprovementreachesamaximum
u... | d:\Daily_ihep\Weekly Progress Report\20260425\110_SAP2025\THP - Poster Session_ THP\THP24.pdf | 2 |
4fb0ff22-bb54-4ad7-86c7-e0fc3836792d | REFERENCES
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5629df38-774a-4a84-81a9-4b88459a77ff | ANALYTICAL STUDY OF FRINGE FIELDS AND NONLINEAR
TRANSPORT IN A SECTOR-BASED ENERGY ANALYSIS SYSTEM∗
Y. Wang†, Y. Zeng†, D. Xiao†, H. Hu, K. Liu, T. Hu‡
Huazhong University of Science and Technology, Wuhan, China
Y. Lu, G. Feng, University of Science and Technology of China, Hefei, China
Abstract
EnergyAnalysis(EA)syste... | d:\Daily_ihep\Weekly Progress Report\20260425\110_SAP2025\THP - Poster Session_ THP\THP34.pdf | 0 |
999c34b4-947e-4e52-a06e-4da29ae123c8 | derivationisvalidatedwithsimulations,andcorrectionof
second-order aberration errors is explored via data process-
ing.Thesemethodsandconclusionsimprovetheaccuracy
of built/operational EA systems without extra costs.
INTRODUCTION
Injectorsareregardedascorecomponentsofvariouselec-
tron accelerator–based facilities [1,2].... | d:\Daily_ihep\Weekly Progress Report\20260425\110_SAP2025\THP - Poster Session_ THP\THP34.pdf | 0 |
c5091606-fc31-48f4-9991-d619bd5b267c | isobtainedbymeasuringthe bunchsizeatthe downstream
end of the EA system [6,7]. When a electron with initial
transverse offset 𝑥0, angular deviation 𝑥′
0, and momentum
deviation 𝛿passesthroughasystemcharacterizedbyatrans-
fermatrix 𝑀, the horizontal displacement at the the system
end can be expressed as 𝑥1= 𝑚11𝑥0... | d:\Daily_ihep\Weekly Progress Report\20260425\110_SAP2025\THP - Poster Session_ THP\THP34.pdf | 0 |
83385ec3-a9a1-4cb4-bf72-9d721b324827 | ∗Work supported by the National Natural Science Foundation of China
(No.1257051916andNo.12341501)andtheNationalKeyR&DProgram
ofChina (No.2024YFA1612200)
†Equalcontribution
‡TongningHu@hust.edu.cncess,andthesourcesofmomentumdispersionmeasurement
errorsandtheircorrectionmethodsarefurtherexploredin
this study.
ANALYTICAL ... | d:\Daily_ihep\Weekly Progress Report\20260425\110_SAP2025\THP - Poster Session_ THP\THP34.pdf | 0 |
a1092a74-affc-47ec-b94c-219cb27f8c1d | 0. Starting from the Hamiltonian equation, the magnetic
field components of the fringe fields are substituted into
the equations of motion and integrated within the fringe
regions[15,16].Neglectinghigh-orderterms,theexpression
for a electron with the initial state (𝑥0,𝑝𝑥0,𝑦0,𝑝𝑦0)after
passingthrough the entrancef... | d:\Daily_ihep\Weekly Progress Report\20260425\110_SAP2025\THP - Poster Session_ THP\THP34.pdf | 0 |
780d70ec-e186-45e2-b76f-3faca1a19f58 | ⎧{{{{{{{
⎨{{{{{{{⎩𝑥2=cos𝜃
2𝜌𝑝𝑧𝑦2
0+𝑥0cos𝜃+𝜌𝑝𝑥0sin𝜃,
𝑝𝑥2= −sin𝜃
2𝜌2𝑝𝑧𝑦2
0−sin𝜃
𝜌𝑥0+𝑝𝑥0cos𝜃,
𝑦2=⎛
⎝1−𝑝𝑥0𝜃
𝑝𝑧⎞
⎠𝑦0+𝜌𝜃𝑝𝑦0,
𝑝𝑦2= −𝑝𝑥0
𝜌𝑝𝑧𝑦0+𝑝𝑦0.(2)
Thentheelectronmotionthroughtheexitfringefieldregion
isintegrated bythe sameanalyticalmethod as theentrance | d:\Daily_ihep\Weekly Progress Report\20260425\110_SAP2025\THP - Poster Session_ THP\THP34.pdf | 0 |
539306fb-3e18-4eeb-adc1-20134653a307 | Figure 1: Comparison between theory and simulation of the bunch phase space: (a)-(c): 𝑥−𝑦for𝑥0=0mm,𝑦0=−33mm
and fringefield region 𝑠1=0.1m, respectively;(d)-(f): absoluteerrors inx andy forthe same cases.
fringe fieldregion, yieldingthe final electronstate:
⎧{{{{{{{
⎨{{{{{{{⎩𝑥3=cos𝜃
2𝜌𝑝𝑧𝑦2
0+𝑥0cos𝜃+𝜌𝑝𝑥0... | d:\Daily_ihep\Weekly Progress Report\20260425\110_SAP2025\THP - Poster Session_ THP\THP34.pdf | 1 |
4c541a02-32a1-4fa8-ab06-d6506e916919 | LARGE MOMENTUM SPREAD
Within the sector magnets, the deflection trajectory of
electrons is determined by their momentum. When momen-
tum spectrum is measured with the EA system, it is prac-
tice to rely on the linear transport theory.This approach canleadtoanincreaseinnonlineartransmissionerrorsduring
themeasurementofb... | d:\Daily_ihep\Weekly Progress Report\20260425\110_SAP2025\THP - Poster Session_ THP\THP34.pdf | 1 |
722593af-5439-44d8-bfce-4cb0e9105272 | ingly, the horizontal displacement of the electron relative to
the reference one at the exit of the bending section can be
obtained throughgeometric relations.
𝑥 = 𝜌(𝛿)sin𝜃(𝛿)
sin𝜃0−𝜌0. (4)
Then aTaylorexpansion of 𝑥around𝛿 = 0is performed:
𝑥 = 𝑘1𝛿+𝑘2𝛿2+𝑘3𝛿3+𝑜(3), (5)
where,𝑘𝑖represents the coefficie... | d:\Daily_ihep\Weekly Progress Report\20260425\110_SAP2025\THP - Poster Session_ THP\THP34.pdf | 1 |
330206cc-447b-461f-862c-8534d7d5a005 | where𝑃 = 𝑝𝑧(1+𝛿). Therefore, based on the analytical
trajectory (𝑥,𝑦,𝛿)derivedfromtheinitialstate (𝑥0,𝑦0,𝛿),
and combined with the measured data of 𝑥and𝑦on the
fluorescent screen, the measurement result of the electron
momentum deviation can be obtained.
The actual fringe field is more complex and does not
... | d:\Daily_ihep\Weekly Progress Report\20260425\110_SAP2025\THP - Poster Session_ THP\THP34.pdf | 2 |
6cfe2555-d132-4bc3-aa54-bdd399c8beaf | has an initial offset in the 𝑦-direction, as shown in Fig. 1(a),
the maximum displacement obtained from the theoretical
modelis6×10−4m.Ifthebeambunchhasoffsetsinboth
𝑥and𝑦,the maximumdeviationis 1×10−4m,as shownin
Fig.1(b). Furthermore, whenfringefields with quadrupole
components are considered, as shown in Fig. 1(c... | d:\Daily_ihep\Weekly Progress Report\20260425\110_SAP2025\THP - Poster Session_ THP\THP34.pdf | 2 |
f55ae584-a5bb-4dbc-80d1-1b4a86f63d78 | using the COSY.
CONCLUSION
The influences of fringe fields and nonlinear transport
within the EA system are analyzed, leading to improved
accuracyandreliabilityofmomentum dispersionmeasure-
ments in systems without additional cost. Future research
will refine the compensation mechanism for complex fringe
fields using s... | d:\Daily_ihep\Weekly Progress Report\20260425\110_SAP2025\THP - Poster Session_ THP\THP34.pdf | 2 |
c17720d4-0784-48da-94d9-58a41b2b3756 | 317341, 2015. doi:1/zero.alt4.339/zero.alt4/photonics2/zero.alt42/zero.alt4317
[3]Y. Wang, X. Jiang, G. Yang, et al., “Time-resolved energy
spectrum measurement of a linear induction accelerator withthe magnetic analyzer” , Chin. Phys. C , vol. 39, no. 1, p.
017004, 2015. doi:1/zero.alt4.1/zero.alt488/1674-1137/39/1//z... | d:\Daily_ihep\Weekly Progress Report\20260425\110_SAP2025\THP - Poster Session_ THP\THP34.pdf | 2 |
f3c57c24-6cde-4be2-a22f-3e319e3c4130 | [6]T. Hu, Y. Zeng, and K. Liu, “Design considerations of a
magnet-based diagnosis system with compact layout for typi-
cal beam injector”, IEEE Trans. Appl. Supercond. , 2024.
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[7]S. Zhang, C. Meng, Z. Zhou, et al., “Design of 10 MeV
electronlinearacceleratorforsp... | d:\Daily_ihep\Weekly Progress Report\20260425\110_SAP2025\THP - Poster Session_ THP\THP34.pdf | 2 |
23e62151-5029-4ae9-a707-09c44057fa18 | vol.35, pp. 278-287, 1964. doi:1/zero.alt4.1/zero.alt463/1.17188/zero.alt46
[10]K. L. Brown, “A first- and second-order matrix theory for
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0c78512d-6514-48ee-a134-17e8d0d0236a | andthird-ordertransfercoefficientsforarbitraryfields”, IEEE
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[15]G. E. Lee-Whiting, “First- a... | d:\Daily_ihep\Weekly Progress Report\20260425\110_SAP2025\THP - Poster Session_ THP\THP34.pdf | 2 |
ca736a6b-8b3f-4084-8977-2d05237ef6d0 | doi:1/zero.alt4.1/zero.alt416//zero.alt4168-9/zero.alt4/zero.alt42(9/zero.alt4)91317-5
[17]M. Berz and K. Makino, “COSY INFINITY Version 8.1 –
User’sGuideandReferenceManual”,DepartmentofPhysics
andAstronomy,MichiganStateUniversity,Rep.MSUHEP-
20704, 2002. | d:\Daily_ihep\Weekly Progress Report\20260425\110_SAP2025\THP - Poster Session_ THP\THP34.pdf | 2 |
c3d320d0-5edf-4d67-9470-58101cb03e09 | PHYSICAL DESIGN OF MICROWA VE ELECTRON GUN OPTIMIZED
FOR CARBON NANOTUBE CATHODES*
Tianhui He†
Institute of Applied Electronics, Chinese Acad emy of Engineering Physics, Mianyang, China
Abstract
Since the maximum electric field strength that a carbon
nanotube field-emission cathode can withstand is less than
13 ... | d:\Daily_ihep\Weekly Progress Report\20260425\110_SAP2025\THP - Poster Session_ THP\THP37.pdf | 0 |
b8a33d27-6bce-4b35-880f-f99f2002600a | radio frequency (RF) design of the electron gun was com-
pleted through fine parameter adjustment of the cavity structure. Finally, the engine ering design of the electron
gun was accomplished after considering multiple aspects
such as the gun's assembly, cathode structure, microwave
feed-in structure, and electro n... | d:\Daily_ihep\Weekly Progress Report\20260425\110_SAP2025\THP - Poster Session_ THP\THP37.pdf | 0 |
c7f1c147-8443-45c3-ab58-626299ba97b1 | performance and stability have been continuously im-
proved, and cold cathode electron guns have also been ini-tially applied in fields such as small vacuum devices and
pulsed power systems. However, challenges remain in the
generation of high-brightness and high-stability beams, es-pecially in the practical applicat... | d:\Daily_ihep\Weekly Progress Report\20260425\110_SAP2025\THP - Poster Session_ THP\THP37.pdf | 0 |
ff220aa9-b166-4ead-849c-48eed97c811b | pulsed beams, providing a new path for scenarios with
strict requirements on time re solution, such as free-electron
lasers and medical radiotherapy [3, 4]. Therefore, the de-
velopment of cold cathode microwave electron guns is cru-
cial for the miniaturization an d integration of accelerators.
CNTs, with their hig... | d:\Daily_ihep\Weekly Progress Report\20260425\110_SAP2025\THP - Poster Session_ THP\THP37.pdf | 0 |
e03d929b-9e53-4c4e-bfcb-51ecdb773fa3 | damage and performance degradation [6, 7].
To address this issue, this paper optimizes the physical
design of the microwave elect ron gun based on the charac-
teristics of CNTs cathodes: shortening the cavity length to
reduce the residence time of electrons in the cavity, and in-troducing a nose cone struct ure to o... | d:\Daily_ihep\Weekly Progress Report\20260425\110_SAP2025\THP - Poster Session_ THP\THP37.pdf | 0 |
cc4ba8a6-5d45-4678-951b-aad23f5e24ac | were tested. Based on the more representative test results among them, we designed a si ngle-cavity RF-gun using a
carbon nanotube thin-film cathode.
Field Emission Characteristics of CNTs
Figure 1: Test Results: (a) Field emission current waveform
and reflection waveform; (b) Fitting curve of field emis-sion c... | d:\Daily_ihep\Weekly Progress Report\20260425\110_SAP2025\THP - Poster Session_ THP\THP37.pdf | 0 |
75aa1c20-0df5-453a-a9f1-69e537a9b069 | film cathode is approximately 40 mA (with a cathode field-emission diameter of 6 mm and a current density of
0.14 A/cm²), among which the field enhancement factor is
___________________________________________
* Work supported by Infrared terahert z free electron laser device project.
† htth111@163.com | d:\Daily_ihep\Weekly Progress Report\20260425\110_SAP2025\THP - Poster Session_ THP\THP37.pdf | 0 |
491c4622-9e28-4342-b048-0595764dcff4 | about 1179 and the root-mean-square (RMS) phase width
is roughly 17.2°. Based on the above experimental data, the
ASTRA software was used to conduct beam dynamics sim-
ulation on the RF-gun of the cold cathode test platform. The simulation parameters were set as follows: cathode
field-emission diameter of 6 mm, long... | d:\Daily_ihep\Weekly Progress Report\20260425\110_SAP2025\THP - Poster Session_ THP\THP37.pdf | 1 |
8cad9de7-64a9-46ea-8a77-caaf70fe0db0 | CNTs cathode can withstand is 13 MV/m (a relatively low
electric field strength), the use of a conventional single-
cavity Pillbox cavity will lead to severe back-bombard-
ment. To reduce electron back-bombardment and achieve
a certain beam bunching effe ct, a cavity structure with a
nose cone added at the cathode e... | d:\Daily_ihep\Weekly Progress Report\20260425\110_SAP2025\THP - Poster Session_ THP\THP37.pdf | 1 |
74c43acb-91a4-42e2-8c57-d40cfdfd331b | eigenmode by adjusting and modifying the cavity radius
R0, equatorial ridge height Lx, and chamfer radius Ra of
the cavity's rear wall.
Beam Dynamics Simu lation of the RF-gun
Based on the selection of th e cavity structure, beam dy-
namics simulation and optimization of the RF-gun were
conducted using the field ... | d:\Daily_ihep\Weekly Progress Report\20260425\110_SAP2025\THP - Poster Session_ THP\THP37.pdf | 1 |
2a339174-c55a-4568-8849-315e7a019f2a | electron beam kinetic energy an d energy spread: the kinetic
energy at the electron gun exit exceeds 40 keV , and the en-
ergy spread of the beam bunch at the exit is less than 60%.
Figure 3(c) displays the longitudinal momentum distribution of the beam bunch, from which it can be ob-
served that the beam bunch lengt... | d:\Daily_ihep\Weekly Progress Report\20260425\110_SAP2025\THP - Poster Session_ THP\THP37.pdf | 1 |
1094ebe4-ee44-4960-bc00-c7ef7511839b | lowering electron back-bombardment.
Figure 3: Beam dynamics optimization results of the cold
cathode RF-gun: (a) Emittance optimization results;
(b) Longitudinal kinetic energy distribution and energy spread distribution; (c) Longitudinal momentum distribu-
tion of the beam bunch at the electron gun exit; (d) Lo... | d:\Daily_ihep\Weekly Progress Report\20260425\110_SAP2025\THP - Poster Session_ THP\THP37.pdf | 1 |
b4f7b6e5-5ef5-4b03-b3c7-d8ddd1b82089 | eigenmode design. After the eigenmode optimization, the
resonant frequency of the RF-gun was 2855.937 MHz, and
the unloaded quality factor Q
0 was 5983.
The design of the microwave coupling structure required
the use of a driven-mode desi gn module. The main objec-
tives of the RF-gun driven-mode design were as fol... | d:\Daily_ihep\Weekly Progress Report\20260425\110_SAP2025\THP - Poster Session_ THP\THP37.pdf | 1 |
9bcae8fd-2fc2-4dbf-81bb-df25b8f849fb | electric field strength on th e cathode surface can reach
73.76 MV/m. The coupling degree of the coupling hole at
the microwave coupling frequency is approximately
1.7456, and it can be seen from the SMITH chart that the coupling state is over-couplin g. The coupling degree of the
probe at a frequency of 2856 MHz i... | d:\Daily_ihep\Weekly Progress Report\20260425\110_SAP2025\THP - Poster Session_ THP\THP37.pdf | 2 |
9a61b138-4e27-4851-9e92-66bec74a5c6d | strength and thermal conductivity of pure copper, a com-
plete mechanical structure desi gn of the electron gun was
carried out. Given that the microwave pulse repetition fre-
quency of the cold cathode test platform is relatively low, which will not cause significant heat accumulation, a sep-
arate thermal conductivi... | d:\Daily_ihep\Weekly Progress Report\20260425\110_SAP2025\THP - Poster Session_ THP\THP37.pdf | 2 |
94f14a67-b99e-47d4-b6a4-76b77b07d96c | consistent dimensions are symmetrically opened on the up-
per and lower parts of the cavity to ensure the symmetry of microwave coupling.
The upper part of the cavity is rigidly connected to the
tapered waveguide, and a vacuum SNAC negative flange is welded on the top of the waveguide to realize the vacuum
isolation... | d:\Daily_ihep\Weekly Progress Report\20260425\110_SAP2025\THP - Poster Session_ THP\THP37.pdf | 2 |
9fb0afe6-be0e-42fd-beee-3010050ebbd8 | parts such as the cathode hold er, cathode transmission rod,
bellows, and slide rail, which can realize precise position-ing and flexible adjustment of the cathode. The layout and
assembly relationship of all components of the electron
gun are shown in the exploded view of Figure 5.
Figure 5: Exploded view of ... | d:\Daily_ihep\Weekly Progress Report\20260425\110_SAP2025\THP - Poster Session_ THP\THP37.pdf | 2 |
78db999c-c2a4-49d0-a39f-47bfd4cffdbb | test platform, the proportion of electron back-bombard-
ment is drastically reduced from 40.51% to 5.6%.
REFERENCES
[1] C. A. Spindt, I. Brodie, L. Humphrey, and E. R. Westerberg,
“Physical properties of thin-fi lm field emission cathodes with
molybdenum cones”, J. Appl. Phys. , vol. 47, no. 12, pp.
5248–5263, Dec... | d:\Daily_ihep\Weekly Progress Report\20260425\110_SAP2025\THP - Poster Session_ THP\THP37.pdf | 2 |
e503e8ed-4b1c-4a48-ad55-32cca42a6d3b | tron microscope”, Microsyst. Nanoeng. , vol. 7, no. 1,
Jun. 2021. doi:10.1038/s41378-021-00268-9
[5] Y . Saito and S. Uemura, “Field emission from cabon nano-
tubes and its applicati on to electron sources”, Carbon , | d:\Daily_ihep\Weekly Progress Report\20260425\110_SAP2025\THP - Poster Session_ THP\THP37.pdf | 2 |
5c7d1560-9ada-4ccd-bc52-7a0d495c5f41 | vol. 38, no. 2, pp. 169–182, Dec. 2000.
doi:10.1016/S0008-6223(99)00139-6
[6] G. S. Bocharov and A. V . El etskii, “Degradation of a carbon
nanotube-based field-emission cathode during ion sputter-
ing”, Tech. Phys ., vol. 57, no. 7, pp. 1008–1012, Jul. 2012.
doi:10.1134/S1063784212070055 [7] X. Li, M. Li, L. ... | d:\Daily_ihep\Weekly Progress Report\20260425\110_SAP2025\THP - Poster Session_ THP\THP37.pdf | 3 |
a7fa5794-adde-4f12-b121-a5b2b7a6b289 | SPECTRAL FORM FUNCTION WITH APPLICATIONS IN BEAM PHYSICS
Xiujie Deng∗, Institute for Advanced Study, Tsinghua University, Beijing, China
Abstract
Todescribelongitudinalfinestructurelikemicrobunching
within a particle beam, a classical approach is to define a
bunching factor which is the Fourier transform of the parti-
... | d:\Daily_ihep\Weekly Progress Report\20260425\110_SAP2025\THP - Poster Session_ THP\THP42.pdf | 0 |
293c4740-caa2-4757-b68b-331b64fb48e5 | along with its solution in a general coupled linear lattice.
The example applications of SFF in electron storage ring
physics and laser-induced microbunching are presented.
INTRODUCTION
Microbunching enables laser-like radiation generation
from charged particle beam, and is one of the main driv-
ing forces advancing ac... | d:\Daily_ihep\Weekly Progress Report\20260425\110_SAP2025\THP - Poster Session_ THP\THP42.pdf | 0 |
78d65458-cc81-4dba-bd73-e5675789d50b | radiation properties or to control collective beam dynam-
ics.Oneexampleisthe creationofhelicalmicrobunching
forlightgenerationwithorbitangularmomentum[2].The
classical 1D definition of bunching factor is clearly not suf-
ficient in many applications. This justifies our motivation
to investigate such a generalized defi... | d:\Daily_ihep\Weekly Progress Report\20260425\110_SAP2025\THP - Poster Session_ THP\THP42.pdf | 0 |
7b77bab3-41d2-48d9-8d6f-7b3cac1607f4 | dictated by a quadratic Hamiltonian H=X𝑇HX
2, where
H=H𝑇.TheHamiltonianequationinmatrixformisthen
𝑑X
𝑑𝑠=SHX,with Sthesymplecticform.Theevolutionofpar-
ticlestatevectorfromtheinitialpoint 𝑠𝑖tothefinalpoint 𝑠𝑓
can bedescribed bya symplectic transfer matrix according
toX(𝑠𝑓)=R(𝑠𝑓,𝑠𝑖)X(𝑠𝑖),with R(𝑠𝑓,𝑠𝑖... | d:\Daily_ihep\Weekly Progress Report\20260425\110_SAP2025\THP - Poster Session_ THP\THP42.pdf | 0 |
ccf9463b-be81-4a99-b0a0-3c5f6309b8cc | FOKKER-PLANCK EQUATION
Now let us add non-symplectic process, like damping
and diffusion. Here we simplify the discussion by assuming
thatthe dampingcoefficientsareindependent oftheparticle
state vector, for example that of the radiation damping. The
equation of motion is now
𝑑X
𝑑𝑠=(SHX+BX)+𝜉(𝑠),(4)
with the stoch... | d:\Daily_ihep\Weekly Progress Report\20260425\110_SAP2025\THP - Poster Session_ THP\THP42.pdf | 0 |
f3e89788-4617-4608-80dd-ac0686deba7b | Moyalexpansion[4].Thequantumexcitationforexample
is more accurately modeled by a jump-diffusion process.
Denote C≡SH+B ,andnotethat Tr(SH)=0 ,wecanthen
derive the Fokker-Planck equation for𝜓(X)
𝜕𝜓
𝜕𝑠+∇ X(𝜓CX)=1
26∑︁
𝑖=16∑︁
𝑗=1𝐷𝑖𝑗𝜕2𝜓
𝜕X𝑖𝜕X𝑗.(5)
The corresponding equation in spectral domain is
𝜕F
𝜕𝑠−(... | d:\Daily_ihep\Weekly Progress Report\20260425\110_SAP2025\THP - Poster Session_ THP\THP42.pdf | 0 |
9d570829-4201-401d-83a2-ff720eaf2916 | where∇K≡
𝜕
𝜕K1,···,𝜕
𝜕K6𝑇
. From the right hand side of
Eq.(6),itisclearthatdiffusionhasastrongerimpactonhigh-
frequencybunching,i.e.,finerstructuresinphasespace.Also
notethatifthereisnodiffusioninphasespace,i.e.,if D=0,
we have𝑑𝜓
𝑑𝑠=𝜕𝜓
𝜕𝑠+(∇ X𝜓)(CX)=−Tr(C)𝜓=−Tr(B)𝜓 ,
and𝑑F
𝑑𝑠=𝜕F
𝜕𝑠−(KC)(∇ KF)=0... | d:\Daily_ihep\Weekly Progress Report\20260425\110_SAP2025\THP - Poster Session_ THP\THP42.pdf | 1 |
35a6a1e4-9f1c-46b2-a060-3375b7c42d35 | K′≡KP−1andD′≡PDP𝑇, then Eq. (6) can be cast as
𝜕F
𝜕𝑠−∑︁
𝑖K′
𝑖𝜆𝑖𝜕F
𝜕K′
𝑖=−K′D′K′𝑇
2F,(7)
whose general solution is [5]
F(K′,𝑠)=𝑓(K′𝚲,0)𝑒Í
𝑖𝑗1
2𝐷′
𝑖𝑗
𝜆𝑖+𝜆𝑗K′
𝑖K′
𝑗
,(8)
where 𝚲≡diag
𝑒𝜆1𝑠,···,𝑒𝜆6𝑠
, withdiag{···}means
diagonalmatrix.Theexactformof 𝑓(K′,0)isdetermined
by the initial c... | d:\Daily_ihep\Weekly Progress Report\20260425\110_SAP2025\THP - Poster Session_ THP\THP42.pdf | 1 |
cc663a85-9f3d-49ce-bf25-29a249dd811c | 2K′GK′𝑇.(10)
Denote𝜎≡P−1G P−1𝑇, we then have
F(K,𝑠)=𝑒−𝑖K ˆRX0−1
2K𝜎K𝑇.(11)
Note that here ˆR(𝑠,0)=𝑒∫𝑠
0C𝑑𝑠′=P−1𝚲Pis the deter-
ministictransfer matrixwith damping orantidamping. The
abovesolutionofF(K,𝑠)istheFouriertransformofa6D
Gaussian distribution given by
𝑔(X,X 0,𝑠)=exp
−1
2
X− ˆRX0𝑇
𝜎−1
X−... | d:\Daily_ihep\Weekly Progress Report\20260425\110_SAP2025\THP - Poster Session_ THP\THP42.pdf | 1 |
d17677a7-6c56-4c93-9c60-5203081713ac | 𝑖𝑗
𝜆𝑖+𝜆𝑗.
Theevolutionofageneralbeamdistributionisthengiven
by the superposition principle
𝜓(X,𝑠)=∫
𝜓(X 0,0)𝑔(X,X 0,𝑠)𝑑X 0,(17)
from which we have
F(K,𝑠)=F(K ˆR,0)𝑒−K𝜎KT
2.(18)
Withtheaboveanalysisdone,thebeamdistributioncan
then be transported from element to element in a general
coupled lattice. Genera... | d:\Daily_ihep\Weekly Progress Report\20260425\110_SAP2025\THP - Poster Session_ THP\THP42.pdf | 1 |
dc2fc1e6-2f82-40be-b0df-5b5dc6d2314d | Thisresultisusuallyknownasthebeamenvelopemethod[6].
We pointoutthatEqs.(19) and(20)aremore generaland
contain more information than the above evolution of sec-
ond moments. In other words, we can derive Eq. (21) from
Eq. (19) or (20), but not the other way around.
Inanelectronstoragering,theequilibriumstaterepeats
turn... | d:\Daily_ihep\Weekly Progress Report\20260425\110_SAP2025\THP - Poster Session_ THP\THP42.pdf | 2 |
eed8e219-fe50-4ccc-bbc6-c20e507cd9e0 | then
V−1𝚺(V−1)𝑇
𝑖𝑗(𝑠)=
V−1D(𝑠)(V−1)𝑇
𝑖𝑗
1−U𝑖𝑖U𝑗𝑗.(24)
Aftergetting 𝚺′≡V−1𝚺(V−1)𝑇,weonlyneedanothertrans-
formation V𝚺′V𝑇to get the equilibrium 𝚺. In a linear lat-
tice,the equilibriumbeam distributionunder theinfluence
of damping and diffusion will tend to be Gaussian. For a
Gaussianbeamwith ⟨X⟩... | d:\Daily_ihep\Weekly Progress Report\20260425\110_SAP2025\THP - Poster Session_ THP\THP42.pdf | 2 |
23fcccf4-c78c-4b5c-b397-90b3a91d06ee | −1
2X𝑇𝚺−1
0X
.
One-Stage Energy Modulation
Laser-induced energy modulation: 𝛿=𝛿+𝐴sin(𝑘 𝐿𝑧),
with𝑘𝐿=2𝜋
𝜆𝐿the laser wavenumber. Beam evolu-
tion after modulation: X=RX , where Ris the lin-
ear transfer matrix of the magnet lattice. Denote: U𝑝≡ 0 0 0 0𝑝𝑘 𝐿0,M𝑝≡KR−U 𝑝,R𝑖6≡ 𝑅16𝑅26𝑅36𝑅46𝑅56𝑅66𝑇,... | d:\Daily_ihep\Weekly Progress Report\20260425\110_SAP2025\THP - Poster Session_ THP\THP42.pdf | 2 |
bec08a2e-2f72-4788-869d-4b3bd7115940 | storagering,if R=T𝑚
0with T0thesymplecticone-turnmap,
whichmeansthebeamtraversestheringfor 𝑚revolutions
after the laser modulation, then
M𝑝𝚺0M𝑇
𝑝=∑︁
𝜅=𝐼,𝐼𝐼,𝐼𝐼𝐼𝜖𝜅
KT𝜅K𝑇−2KRT𝜅U𝑇
𝑝+U𝑝T𝜅U𝑇
𝑝
.
(26)
The above analysis can be applied in the proof-of-principle
experiment of steady-state microbunching... | d:\Daily_ihep\Weekly Progress Report\20260425\110_SAP2025\THP - Poster Session_ THP\THP42.pdf | 2 |
3115da97-e33f-4c7f-a454-2de76b980bcf | U1,R1𝑖6≡ 𝑅1,16𝑅1,26𝑅1,36𝑅1,46𝑅1,56𝑅1,66𝑇,
R2𝑖6≡ 𝑅2,16𝑅2,26𝑅2,36𝑅2,46𝑅2,56𝑅2,66𝑇.
Following steps similar to above, the final SFF is
F(K)=∞∑︁
𝑝1=−∞∞∑︁
𝑝2=−∞𝐽𝑝1(−M 2R1𝑖6𝐴1)𝑒𝑖𝑝2𝜙
𝐽𝑝2(−KR 2𝑖6𝐴2)exp(
−M1𝚺0M𝑇
1
2)
.(27)
Foraperiodicsystemlikeastoragering,if R1=T𝑚1
0,R2=
T𝑚2
0withT 0the one... | d:\Daily_ihep\Weekly Progress Report\20260425\110_SAP2025\THP - Poster Session_ THP\THP42.pdf | 2 |
16142a26-6b44-497b-88eb-b128b9febed1 | We can use different revolution numbers to play the role of
different𝑅56in the two-stage dispersions of EEHG. For ex-
ample, we can fire the first-shot laser and wait for 2𝑛+1
revolutions, and then we fire the second-shot laser and then
waitfor2revolutions.Finallywecangeneratehighharmonic
bunching at the𝑚×𝑛-th lase... | d:\Daily_ihep\Weekly Progress Report\20260425\110_SAP2025\THP - Poster Session_ THP\THP42.pdf | 2 |
f87a633f-165e-4822-aa4f-3867fbaf64be | SUMMARY
Inthispaper,spectral formfunction(SFF)hasbeenpre-
sentedasatooltostudybeamdynamics.Moreinteresting
work on this is ongoing and will be reported in the future.
The author thanks Alex Chao for helpful discussion.
REFERENCES
[1]X. Deng,Theoretical and experimental studies on steady-
state microbunching. Singapore:... | d:\Daily_ihep\Weekly Progress Report\20260425\110_SAP2025\THP - Poster Session_ THP\THP42.pdf | 3 |
403c5bba-02ef-4fbd-aefe-71078785a96c | 2019.doi:10.1007/978-3-030-18472-8
[5]M. C. Wang, and G. E. Uhlenbeck, “On the theory of the
BrownianmotionII”,Rev. Mod. Phys.,vol.17,no.2-3,pp.
323–342, Apr. 1945.doi:10.1103/RevModPhys.17.323
[6]K. Ohmi, K, Hirata, and K. Oide, “From the beam-envelope
matrix to synchrotron-radiation integrals”,Phys. Rev. E, vol.49, n... | d:\Daily_ihep\Weekly Progress Report\20260425\110_SAP2025\THP - Poster Session_ THP\THP42.pdf | 3 |
8724aa06-ac50-4612-9ddd-3a6c5324169c | Lett., vol. 105, no. 15, p. 154801, Oct. 2010.
doi:10.1103/PhysRevLett.105.154801
[10]X.Denget al.,“Experimentaldemonstrationofthemecha-
nism of steady-state microbunching”,Nature, vol. 590, no.
7847, pp. 576–579, Feb. 2021.
doi:10.1038/s41586-021-03203-0
[11]A.Kruschinskiet al.,“Confirmingthetheoreticalfoundation
ofst... | d:\Daily_ihep\Weekly Progress Report\20260425\110_SAP2025\THP - Poster Session_ THP\THP42.pdf | 3 |
424617c4-6ed4-43f8-a270-b843f5eddc17 | PHYSICAL DESIGN STUDY OF THE MAIN MAGNET FOR THE CIAE
75 MeV CYCLOTRON*
JinRong Lu †, TianJian Bian, ShiZhong An, SuMin Wei, LuYu Ji
China Institute of Atomic Energy, Beijing, China
Abstract
A 75 MeV cyclotron is currently under development at
the China Institute of Atomic Energy (CIAE). This cyclo-
tron is des... | d:\Daily_ihep\Weekly Progress Report\20260425\110_SAP2025\THP - Poster Session_ THP\THP44.pdf | 0 |
597ee210-f011-4864-82c9-8d47043e8c92 | angle at the trailing edges. The isochronous magnetic field
distribution is achieved through an axial shimming
method. Magnetic field optimization was performed using
the numerical simulation software OPERA-3D, thereby en-hancing the acceleration efficiency of the cyclotron. Fur-
thermore, deformation simula tion an... | d:\Daily_ihep\Weekly Progress Report\20260425\110_SAP2025\THP - Poster Session_ THP\THP44.pdf | 0 |
99f781c5-4ed5-446a-8a46-3c8a7dabca84 | we propose the design and construction of a new high-in-
tensity cyclotron capable of delivering an extracted beam
of 75 MeV with a current of 800 μA.
This cyclotron will employ an external ion source for
high-current beam injection. Through the implementation
of high-efficiency injection and extraction systems, h... | d:\Daily_ihep\Weekly Progress Report\20260425\110_SAP2025\THP - Poster Session_ THP\THP44.pdf | 0 |
0b35635c-922d-4462-8bad-9c26973ef015 | quirements, aiming to ensure that the magnetic field distri-
bution satisfies fundamental beam dynamics conditions. The s ystem adopts a four-fol d symmetric structure. The
magnet poles are designed as straight-sided sectors, which
not only enhances the overall symmetry of the cyclotron but also facilitates the desig... | d:\Daily_ihep\Weekly Progress Report\20260425\110_SAP2025\THP - Poster Session_ THP\THP44.pdf | 0 |
98e3f55e-bdb8-43aa-92b8-5db20f45e60f | the machine. The actual pole angle in this design is set to
53°. Furthermore, the influence of the Lorentz force-in-duced stripping effect on beam loss must be considered
during the magnetic field design process, the peak mag-
netic field is limited to below 1.55 T. To avoid breakdown risks in the central region elec... | d:\Daily_ihep\Weekly Progress Report\20260425\110_SAP2025\THP - Poster Session_ THP\THP44.pdf | 0 |
c74af7fc-6468-4bea-b776-f135bc97fd7b | × 1.56 m (height). The system specifically comprises
2 cover plates, 4 return yokes, 8 magnet poles, 8 shimming bars, and 2 central region core columns. The detailed struc-
ture is shown in Fig.1, and the dimensional parameters are
listed in Table 1.
Figure 1: A top view on the 75MeV Cyclotron of CIAE.
___________... | d:\Daily_ihep\Weekly Progress Report\20260425\110_SAP2025\THP - Poster Session_ THP\THP44.pdf | 0 |
6e5b96e3-76f5-4129-b354-50940d59552b | Table 1: Specifications of the 75 MeV Cyclotron
Parame-
ters Value Parameters Value
Energy 75 MeV Current 800 μA
Pole radius 1.485 m Hill gap 38-46 mm
Magnetic
field range 0.2-1.55 T RF fre-
quency 53.3 MHz
RF har-
monic 4rd har-
monic No. of dees 2
Ampere
turns 31000 At Weight 130 t
Electromagnetic fie... | d:\Daily_ihep\Weekly Progress Report\20260425\110_SAP2025\THP - Poster Session_ THP\THP44.pdf | 1 |
c2dfac54-b06c-47a9-b052-c668520668bb | Numerical simulations were employed to optimize the
dimensional parameters of key components of the main magnet, including: the pole angular width, the offset of the
poles relative to the geometric center of the machine, the
pole height and radius, the thickness of the cover plates, the position and size of openings... | d:\Daily_ihep\Weekly Progress Report\20260425\110_SAP2025\THP - Poster Session_ THP\THP44.pdf | 1 |
7d4a6307-69eb-4d53-8d13-69f5d9ab0ea0 | and compatibility between the main magnet and other sys-
tems of the cyclotron [1].
After multiple iterations of optimization, the final mag-
netic field distribution meeting the design requirements was obtained. Figure 3 presents the magnetic field distri-
bution in the mid-plane of the cyclotron; Fig. 4 displays the... | d:\Daily_ihep\Weekly Progress Report\20260425\110_SAP2025\THP - Poster Session_ THP\THP44.pdf | 1 |
caea9173-5954-45eb-9e70-4fd6e57dd6cc | contributing to the magnet de formation, while the effects
of vacuum force and gravitational force are relatively mi-
nor. After optimizing the design of the magnet cover plates
and return yokes, as shown in Fig. 5 ，the maximum defor-
mation of the main magnet was controlled within 100 μm,
the largest deformation, m... | d:\Daily_ihep\Weekly Progress Report\20260425\110_SAP2025\THP - Poster Session_ THP\THP44.pdf | 1 |
7dddf870-d44a-40e1-a166-1c40e2f72686 | BEAM DYNAMICS CALCULATION
Numerical simulations of the magnetic field distribution
in the cyclotron were performed using the beam dynamics
code CYCLOP, yielding the static equilibrium orbits and
the corresponding differential phase slip, expressed as (ω₀/ω − 1) × 1000, where ω₀ is the reference cyclotron an-
gular... | d:\Daily_ihep\Weekly Progress Report\20260425\110_SAP2025\THP - Poster Session_ THP\THP44.pdf | 2 |
92548b1a-90cc-4c75-b935-51e831455f80 | angular width of the poles were optimized through iterative
calculations of the equilibrium orbits, thereby satisfactorily meeting the requirements for an isochronous magnetic
field. Figure 7 shows the resulting isochronism error and
the static integrated phase slip distribution.
Figure 7: isochronism error and... | d:\Daily_ihep\Weekly Progress Report\20260425\110_SAP2025\THP - Poster Session_ THP\THP44.pdf | 2 |
a49114d2-052b-492b-9a8f-6aa8a7dd5f9d | Figure 8: The transverse tune values and Lorentz stripping
loss.
Negative ions such as H ⁻ and D⁻, when accelerated to
high energies, are susceptible to Lorentz stripping due to
their low electron binding energies (0.75 eV for H ⁻). Under
strong magnetic fields, the equivalent electric field may
strip additional... | d:\Daily_ihep\Weekly Progress Report\20260425\110_SAP2025\THP - Poster Session_ THP\THP44.pdf | 2 |
0bda7ea8-dec9-4737-b338-046ff356fe85 | and engineering design of the main magnet for a 75 MeV high-intensity cyclotron. By optimizing the spiral angle at
the pole tip, the axial focusing property of the magnetic
field was effectively improve d, thereby avoiding beam
crossing of harmful resonances and enhancing beam stabil-
ity. Integrating structural def... | d:\Daily_ihep\Weekly Progress Report\20260425\110_SAP2025\THP - Poster Session_ THP\THP44.pdf | 2 |
85ec9a12-867e-430b-b97b-a27c792a2f8f | cyclotrons”, Nucl. Instrum. Methods Phys. Res. B , vol. 269,
no. 24, pp. 2857–2862, Dec. 2011.
doi:10.1016/j.nimb.2011.04.031
[2] M. M. Gordon, “Computation of closed orbits and basic fo-
cusing properties for sector-focused cyclotrons and the de-
sign of ‘cyclops’”, Part. Accel. , vol. 16, pp. 39-62, 1984. | d:\Daily_ihep\Weekly Progress Report\20260425\110_SAP2025\THP - Poster Session_ THP\THP44.pdf | 2 |
e89299e9-a9ef-4c03-a7d6-5cac42917163 | MULTIPLE-ECHO-ENABLEDHARMONICGENERATIONMETHODFOR
STORAGE RING LIGHT SOURCES
Weihang Liu∗, Yu Zhao, Weilun Qin
Institute of High Energy Physics, Chinese Academy of Sciences, Beijing, China
Spallation Neutron Source Science Center, Dongguan, China
Abstract
Storage ring light sources (SRLS) can reuse a single elec-
tronbe... | d:\Daily_ihep\Weekly Progress Report\20260425\110_SAP2025\WEMC - Parallel Talk Session 1_ WEMC\WEMC3.pdf | 0 |
890c8aaf-2a87-49bf-98b8-d729c1313e00 | power and coherence. However, these methods modulate
each bunch onlyonce per revolution, limiting their applica-
tiontoasinglebeamlineandunderutilizingthemulti-userca-
pacityofstoragerings.Toenablecoherentradiationdelivery
to multiple beamlines, we propose a multiple-echo-enabled
harmonic generation scheme. This approa... | d:\Daily_ihep\Weekly Progress Report\20260425\110_SAP2025\WEMC - Parallel Talk Session 1_ WEMC\WEMC3.pdf | 0 |
047dd74b-5067-4914-b924-e28c1fc32103 | compared to third-generation sources. Improving longitu-
dinal coherence can enhance the temporal and energy res-
olution capabilities of the light source, and significant ad-
vancements in these areas would provide users with a more
advancedphotonsource.Infact,manyexpertsbelievethat
thenextgenerationofstorageringlight... | d:\Daily_ihep\Weekly Progress Report\20260425\110_SAP2025\WEMC - Parallel Talk Session 1_ WEMC\WEMC3.pdf | 0 |
06dc81d7-baf9-4495-b1ba-e909af755d19 | be substantially enhanced.
With ongoing research, similar schemes that are more
suitable for storage rings and those enabling higher har-
∗liuwh@ihep.ac.cn
Figure1:Implementationcomplexityofseedingmethodsin
storage rings.
Figure 2: Development of EEHG schemes for storage rings.
monicconversionshavebeenprogressivelyprop... | d:\Daily_ihep\Weekly Progress Report\20260425\110_SAP2025\WEMC - Parallel Talk Session 1_ WEMC\WEMC3.pdf | 0 |
e6281a97-1f77-4080-888f-8c039162d0dc | EEHGscheme.AsshowninFig.2,sinceitsproposal,EEHG
has been continuously explored for application in storage
rings, and numerous schemes tailored for storage rings have
been proposed [6 –10]. By 2024, EEHG was successfully
demonstrated for the first time in a storage ring [17], al-
thoughthewavelengthofthecoherentsignalob... | d:\Daily_ihep\Weekly Progress Report\20260425\110_SAP2025\WEMC - Parallel Talk Session 1_ WEMC\WEMC3.pdf | 0 |
f3b5a717-11a4-4fff-98fd-0a25aa8ab8d1 | This schemeachievesthe generation of coherent pulses for
multiplebeamlinesbyapplyingmultiplemodulationstoa
single bunch.
Thispaperisorganizedasfollows.Inthenextsection,we
will present the theoretical details of MEEHG. Section 3 is
devoted to the verification of this theory. Sections 4 and 5
willdemonstratetheapplicatio... | d:\Daily_ihep\Weekly Progress Report\20260425\110_SAP2025\WEMC - Parallel Talk Session 1_ WEMC\WEMC3.pdf | 1 |
d566b79e-4e45-40fb-b759-f79a483cfe60 | radiation through the downstream undulator.
Subsequently, the excitation of the second echo no longer
requires laser modulation, but only the action of a strong
dispersionsection.Afterthisprocess,coherentradiationis
producedatthesecondradiator.Byrepeatingthisprocedure,
multiple EEHG can be achieved.
Toobtaintheharmonic... | d:\Daily_ihep\Weekly Progress Report\20260425\110_SAP2025\WEMC - Parallel Talk Session 1_ WEMC\WEMC3.pdf | 1 |
a1037a37-3d08-4877-973e-927111520108 | ⎝𝑘𝑧−𝑛+1
∑
𝑖=𝑘+1𝑚𝑖𝑘𝐿⎞
⎠.
(1)
GiventheinfiniteseriesinEq.(1),foranygivenharmonic
order,certaintermsdominatesignificantlyoverothers.We
may approximate the complex bunching factor by retaining
only these dominant terms:
𝑏0,0,…,1,𝑁−1 = 𝐽𝑁−1(𝐴𝑛+1𝐵2𝑛𝑁)𝐽1(𝐴𝑛𝜉)…
×𝐽0(𝐴2𝜉)𝐽0(𝐴1𝜉)exp(−𝜉2/2),(2)
where𝜉... | d:\Daily_ihep\Weekly Progress Report\20260425\110_SAP2025\WEMC - Parallel Talk Session 1_ WEMC\WEMC3.pdf | 1 |
0ef47f4c-783a-4e0f-a7a2-ed65bf9fbb57 | 5 – −13.9551
6 – 0.4639
thefirst𝑛echoesandtheresultingbunchingfactorfollows
a zero-order Bessel function behavior. Consequently, when
noneofthepreceding 𝑛−1echoesareexcited,thebunching
factor reduces, as expected, to the well-known expression
for standard EEHG [18].
THEORETICAL VERIFICATION
Tovalidateourtheory,wecons... | d:\Daily_ihep\Weekly Progress Report\20260425\110_SAP2025\WEMC - Parallel Talk Session 1_ WEMC\WEMC3.pdf | 1 |
ece06c54-6be3-4428-a2b2-d9179e79062c | presentedalongsidetheirtheoreticalcounterpartsinFig.3,
demonstratingexcellentagreementbetweensimulationre-
sults and theoretical predictions.
APPLICATION OF MEEHG TO SAPS FOR
GENERATING COHERENT RADIATION
AT THREE DIFFERENT HARMONICS
WenowapplytheMEEHGschemetotheSouthernAd-
vancedPhotonSource(SAPS)storageringtogenerate... | d:\Daily_ihep\Weekly Progress Report\20260425\110_SAP2025\WEMC - Parallel Talk Session 1_ WEMC\WEMC3.pdf | 1 |
2d3627a6-417b-4c73-bfe5-74d1990cc019 | Table 2: Main Parameters of SAPS
Parameters Values
Energy 3.5GeV
Emittance 𝑥/𝑦 60 / 6 pm
Energy spread 0.1%
Peak Current 32A
Straight section length 6m
Figure 4: MEEHG Layout in the SAPS storage ring and
pulse profiles from different echoes.
To integrate the three-echo scheme into the storage ring,
each strong disper... | d:\Daily_ihep\Weekly Progress Report\20260425\110_SAP2025\WEMC - Parallel Talk Session 1_ WEMC\WEMC3.pdf | 2 |
ee1d8f44-c2b9-43a6-a273-16d8547f0404 | than10meVand a pulse duration of approximately 400fs.
The photon number per pulse reaches the order of 109, rep-
resenting an enhancement of approximately three orders of
magnitude compared to the synchrotron radiation.
APPLICATION FOR GENERATING
COHERENT RADIATION AT THREE
DIFFERENT TIME DURATIONS
Inthissection,wefurt... | d:\Daily_ihep\Weekly Progress Report\20260425\110_SAP2025\WEMC - Parallel Talk Session 1_ WEMC\WEMC3.pdf | 2 |
675bb678-1a4f-47e8-b050-293558ea9a5d | photonnumberofabout 2×109perpulse,whilethepicosec-
Figure 5: Radiation pulses with different durations from the
three-echoprocess,correspondingtothe1st,2nd,and3rd
echo results from top to bottom.
ond pulse reaches a duration of 1.4pswith approximately
7×109photons per pulse.
CONCLUSION
The Multi-EEHG scheme offers a pr... | d:\Daily_ihep\Weekly Progress Report\20260425\110_SAP2025\WEMC - Parallel Talk Session 1_ WEMC\WEMC3.pdf | 2 |
ab668d00-a0f4-4af0-9009-116e6716e7bf | Severalaspectsoftheschemewarrantfurtherinvestiga-
tion. These include more detailed design of the radiation
spectrum and improved independent control over individual
beamlines.
ACKNOWLEDGEMENTS
This work was supported by National Natural Science
Foundation of China (No. 12405176).
REFERENCES
[1]B.Girard etal.,“Opticalf... | d:\Daily_ihep\Weekly Progress Report\20260425\110_SAP2025\WEMC - Parallel Talk Session 1_ WEMC\WEMC3.pdf | 2 |
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[4]H. Deng and C. Feng, “Using off-resonance laser modula-
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wavelengthradiation”, Phys.Rev.Lett. ,vol.111,p.084801, | d:\Daily_ihep\Weekly Progress Report\20260425\110_SAP2025\WEMC - Parallel Talk Session 1_ WEMC\WEMC3.pdf | 2 |
322157ea-159d-4aab-a34a-7d933cf4f2ab | 2013. doi:1/zero.alt4.11/zero.alt43/PhysRevLett.111./zero.alt4848/zero.alt41
[5]C.FengandZ.Zhao,“Astorageringbasedfree-electronlaser
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[6]C.Evainetal.,“Softx-ra... | d:\Daily_ihep\Weekly Progress Report\20260425\110_SAP2025\WEMC - Parallel Talk Session 1_ WEMC\WEMC3.pdf | 3 |
1b017ccf-22e6-471d-8be9-6b4768bd5987 | [8]W. Liu et al., “Generation of two-color polarization-
adjustableradiationpulsesforstorageringlightsource”, Nucl.
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[9]J.-G. Hwang et al., “Generation of intense and coherent sub-
femtosecondX-raypulsesinelectro... | d:\Daily_ihep\Weekly Progress Report\20260425\110_SAP2025\WEMC - Parallel Talk Session 1_ WEMC\WEMC3.pdf | 3 |
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