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The free electron laser (FEL) is the brightest available source of x-rays, surpassing other options by more than ten orders of magnitude. The FEL's short ($\sim$femtosecond), high power ($\sim$gigawatt), coherent x-ray pulses are uniquely capable of probing ultrafast and ultrasmall atomic and molecular dynamics and structure, making them an invaluable research tool for biology, chemistry, material science, physics, medicine, and other fields. Unfortunately, all extant x-ray FELs rely on long rf linacs and undulators, with a footprint of kilometers and a cost on the order of a billion dollars. This severely limits the number of x-ray FELs, with the half dozen existing installations funded at the nation state level. These facilities are significantly oversubscribed, to the detriment of scientific and technological progress. Therefore, attempts to reduce the size and cost of FELs are an active area of research in an effort to increase access to these powerful research tools, with the goal of making x-ray FELs affordable to universities and companies. One of the approaches being researched is the laser plasma accelerator (LPA). The LPA uses an ultra-high intensity laser to eject plasma electrons from a bubble region, producing longitudinal accelerating fields more than three orders of magnitude higher than what can be achieved in an rf linac. In principle, this could shrink the FEL accelerating section from the kilometer scale to a tabletop. To date though, despite continual progress and refinement over the last decade, LPA beam quality has not yet reached the level where it can be directly used as an FEL driver due to stringent constraints on the lasing dynamics.The BELLA FEL experiment at Lawrence Berkeley National Lab intends to decompress the beam to skirt some of the beam quality requirements, by stretching the beam longitudinally and reducing local energy spread. This dissertation will discuss the design and implementation of two subsystems essential for the successful operation of this experiment. The first of these is a coherent transition radiation bunch length diagnostic, which is required to measure the length of the LPA bunches and extrapolate other details about the experiment's performance. The second is an electromagnetic chicane which performs the decompression of the electron beam. A final chapter explores the use of advanced undulators to enable the next generation of LPA driven FELs without decompression and discusses methods for realizing such undulators.

The speed value of 30 km/h should not be exceeded in urban areas, both to ensure safety requirements for all categories of users and to improve the overall quality of life in urban areas. Moreover, it is necessary not only to comply with the prescribed maximum speed, but also to ensure a uniform speed by limiting the variations in relation to the average value within an acceptable range of variation. An original analysis methodology is therefore proposed, useful for both technicians and administrators to verify the effectiveness of traffic calming measures, especially in areas where these measures are widely used, such as Zones 30. This methodology, called SPEIR (acronym for Speed Profile, Effectiveness Indicators and Results, which are the keywords of the three steps into which the proposed methodology is divided), is divided into three operational steps necessary to both verify the effectiveness of existing traffic calming measures in a given context and to plan new traffic calming measures to be implemented in specific urban sectors to be requalified and revitalized. Finally, three case studies are presented where the application of the SPEIR methodology is useful not only for understanding the operational steps in the application of the methodology itself, but also for understanding the differences in terms of the safety performance that the various traffic calming measures provide to the users of the urban streets where such measures are present.

Traffic calming merupakan salah satu cara yang dapat digunakan untuk mengelola kecepatan. Salah satu jenis traffic calming yang terbukti efektif mereduksi kecepatan dan mengurangi volume lalu lintas adalah chicane. Namun sayangnya chicane tidak popular digunakan di Indonesia. Untuk itu penelitian ini bermaksud untuk menguji efektivitas chicane dalam mereduksi kecepatan kendaraan agar dapat menjadi alternatif traffic calming di Indonesia. Metode yang digunakan dalam penelitian ini adalah simulasi lapangan dengan menggunakan taffic cone dan rambu portable dalam mengimplementasikan chicane. Model chicane yang digunakan adalah model chicane dari Pedoman Perencanaan Fasilitas Pengendali Kecepatan Lalu Lintas (model 1) dan Pennsylvania’s Traffic Calming Handbook (model 2). Lokasi studi merupakan jalan lokal yang menjadi blacksite, yaitu Jalan Pemuda Kabupaten Kebumen, Jawa Tengah, Indonesia. Hasil penelitian menunjukkan bahwa kedua model chicane efektif dalam mereduksi kecepatan. Chicane model 1 mampu mereduksi kecepatan pada masing-masing arah sebesar 20% dan 17%, sedangkan pada model 2 sebesar 38,2% dan 39,6%. Namun demikian, kapasitas jalan pada saat implementasi chicane model 2 mengalami penurunan yang sangat drastis, dari kapasitas jalan sebesar 1.516,54 smp/jam pada kondisi eksisting menjadi sebesar 1.527 smp/jam. Oleh karena itu, chicane model 1 lebih disarankan untuk diimplementasikan pada lokasi studi dengan kombinasi pita penggaduh sebelum memasuki chicane

Chicane merupakan salah satu perangkat traffic calming yang banyak digunakan di negara maju. Penelitian mengenai efektivitas chicane sebagai perangkat traffic calming telah dilakukan oleh peneliti sebelumnya dengan menggunakan simulasi lapangan. Penelitian ini bertujuan untuk menyediakan alternatif cara simulasi yang lebih efisien dan aman, disamping juga bisa dapat menganalisis Measure of effectiveness (MOE) dengan lebih komprehensif. Dengan menggunakan data sekunder berupa data observasi geometrik jalan, volume kendaraan, komposisi kendaraan, dan kecepatan kendaraan maka dibuatlah model penerapan chicane dengan menggunakan VISSIM. Penelitian ini menghasilkan kesimpulan yang sejalan dengan penelitian sebelumnya. Hal ini menunjukkan bahwa VISSIM dapat digunakan untuk mensimulasikan penerapan traffic calming, dalam hal ini chicane. MOE yang dihasilkan adalah kecepatan setempat, kecepatan tempuh, kepadatan dan tundaan. Dengan demikian terbuka peluang untuk dapat memanfaatkan VISSIM sebagai alat bantu penerapan traffic calming, maupun pengembangan chicane secara khusus.

[ES] A lo largo del Trabajo Final de Máster se va a realizar un estudio de soluciones para mejorar la seguridad vial de la carretera CV-190 en su paso por el término municipal de Figueroles, provincia de Castellón. Para ello, en primer lugar, se analizará la situación existente del tramo y posteriormente se presentarán las distintas alternativas que puedan conformar una puerta de entrada al municipio entre ellas se encuentran: glorieta, chicane, mediana con implantación de cojines y semaforización del tramo. Tras realizar un análisis multicriterio, teniendo en cuenta distintos factores, se determinará la alternativa que resulte más ventajosa y se desarrollará en mayor medida: realizando un estudio del trazado que debe adoptar, el dimensionamiento del firme y del drenaje, así como la señalización que debe disponerse. Finalmente se proporcionará una valoración económica de la implantación de esta medida.

In recent years, in which a considerable increase in the road traffic volumes has been witnessed, traffic calming has become one the key issues in the area of road engineering. This concerns, in particular, trunk roads passing through small villages with a population of up to 500 and the road section length within the village limits of ca. 1400–1700 m. A successful traffic calming scheme must involve primarily effective reduction in inbound traffic speed. A review of the data from various countries revealed that chicanes installed in the transition zones may have a determining effect on the success of the traffic calming project. The effectiveness of such chicanes depends mainly on the type of chicane, its location on the carriageway, its shape and the size of the lateral deflection imposed by the chicane on the inbound lane. The purpose of this study was to identify the speed reduction determinants in traffic calming schemes in village transition zones, based on a central island horizontally deflecting one lane of a two-lane two-way road with 50 km/h speed restriction. As part of the study, vehicle speeds were measured just before and after the chicanes under analysis. Furthermore, the inbound lane traffic volumes were measured in field and a number of factors were identified, including the applied traffic management scheme, road parameters, view of the road ahead and of the village skyline, isolated buildings, road infrastructure and adjacent roadside developments. The obtained data were analysed with a method employing tautologies of the selected 32 factors affecting the drivers’ perception. A single aggregate parameter was proposed for assessing the coincidence of the influence of selected factors on speed reduction. The analysis of the existing schemes and the results of statistical analyses carried out in this study confirmed the authors’ hypothesis that the combined selected factors produce a desirable effect and that they should be additionally enhanced by the application of solar powered devices.

Vehicle speed is one of the main risk factors for road traffic safety. To increase the level of road safety, especially in urban areas, measures must be implemented to reduce vehicle speed. The installation of calming measures on a road network is systematically planned way to reduce driving speeds. This paper studies the effectiveness in terms of speed reduction of three types of traffic calming measures: 1) speed table, 2) chicane, and 3) road narrowing. The speed analyses regard a series of traffic calming measures located in urban contexts of Catania Province (Italy). For each of these traffic calming measures, experimental investigations were carried out relating to the measurement of speed. The study has shown that the speed tables represent the measure of traffic calming that guarantees the greatest conditioning on speed (it is also possible to halve the average speed). Even the chicanes have a significant impact on reducing speed, as well as the speed tables (average speed is reduced by up to 50%), while road narrowing allows maximum reductions in average speed of around 35%. Furthermore, all three traffic calming measures have resulted in a reduction of accidents always greater than 30%. In the case of speed tables, the reduction in accidents exceeds even 40%. The consequences of road accidents are also mitigated thanks to the traffic calming interventions considered. The reduction of injured people is between 32% (road narrowing) and 50% (chicane). The speed tables involve a reduction of almost 40% of injured people while fatal accidents are completely eliminated. Finally, it has been observed that the reduction in pedestrian injuries is between 33% (road narrowing) and 50% (speed tables). In the case of the chicane the reduction of injured pedestrians is 40%. The pedestrian fatal accidents in the road section in which the speed tables were subsequently installed have been reduced to zero.

AYDIN, Metin Mutlu/0000-0001-9470-716X; Gunay, Prof Banihan/0000-0002-4640-417X WOS: 000503433200009 Urban streets are becoming noisy, less safe and unattractive places due to high traffic volumes and vehicular speeds. Especially, high speeds causes many problems such as traffic accidents, noise, etc. To prevent these problems and negative effects of speeding, traffic calming measures have been widely used in many developed countries. In this study, the effectiveness of ten most common chicane types on speed limit compliance were examined by comparing and ranking chicanes according to their performance. For this purpose, a "Safety Index" was developed and an Ordinary Least Square Regression analysis was performed to identify safest chicane types for undivided two-lane and divided four-lane roads by using various parameters. Additionally, statistical tests were conducted to determine the most important driver characteristics of drivers before and inside the chicanes. For the analyses, all necessary data were obtained from the driving tests of 106 volunteers using a driving simulator. For the simulation scenarios, Akdeniz University's (Antalya/Turkey) campus roads were selected as a case area. The results showed that Chicane Types 2 (CT-2) and 7 (CT-7) have the highest Safety Index values (0.69 and 0.98) and they were found to be the most proper CTs for the undivided and divided roads, respectively. From the statistical tests, it was also found that education level, gender and driving license duration were found to be the statistically significant parameters on speed choice for the most proper chicane types. Additionally, it was concluded that the most important driver characteristics are determined as age (has a negative effect) and gender (to be male has a positive effect) of drivers before and inside the chicanes. All these findings show that the investigation of different CTs has a great potential to reduce speeds and ensure safety in urban minor roads to limit vehicle speeds. Research Office of Akdeniz University (BAP)Akdeniz University [FBA-2015-225]; BAP This study was conducted under a research project titled "Investigation of Chicanes from the Viewpoint of Turkish Driver and Road Characteristics" (FBA-2015-225), which was supported by The Research Office of Akdeniz University (BAP). The authors would like to thank BAP for this support. The authors also thank Research Assistant Kadir Mercan and Technician Sedat Alcan for their support in the preparation of the driving simulator environment and software.

This paper presents expected THz radiation spectra emitted by micro-bunched electron beams produced using a slit-mask placed within a magnetic chicane in the FAST (Fermilab Accelerator Science and Technology) electron injector at Fermilab. Our purpose is to generate tunable narrow-band THz radiation with a simple scheme in a conventional photo-injector. Using the slit-mask in the chicane, we create a longitudinally micro-bunched beam after the chicane by transversely slicing an energy chirped electron bunch at a location with horizontal dispersion. In this paper, we discuss the theory related to the micro-bunched beam structure, the beam optics, the simulation results of the micro-bunched beam and the bunching factors. Energy radiated at THz frequencies from two sources: coherent transition radiation and from a wiggler is calculated and compared. We also discuss the results of a simple method to observe the micro-bunching on a transverse screen monitor using a skew quadrupole placed in the chicane., Comment: 25 pages, 8 figures

Physical review accelerators and beams 23(12), 122801 (2020). doi:10.1103/PhysRevAccelBeams.23.122801, We present first experimental results of a novel method to study the energy chirp of the electron beam lasing window at a free-electron laser operating in self-amplified spontaneous emission mode. The method requires a single magnetic chicane splitting the FEL undulator into two parts of several gain lengths each. Undulator segments should have variable gaps. By scanning both the delay in the chicane and detuning in a part of the undulators, one can retrieve the linear component of both the radiation frequency chirp and the electron energy chirp. In addition, such scan improves the accuracy of the previously proposed autocorrelation-based pulse duration measurement technique. The proposed method targets facilities that lack direct diagnostics of the electron beam longitudinal phase space distribution. It also can be extended to diagnose transverse tilts of the beam., Published by American Physical Society, College Park, MD

Electron bunch compressors formed of achromat arcs have a natural advantage over the more commonly used chicane compressors in that linearisation of the longitudinal phase space is of the correct sign to compensate for the curvature imprinted by rf acceleration. Here we extend the utility of arc compressors to enable variation of the longitudinal compaction within a fixed footprint. We also show that this variability can be achieved independently order-by-order in momentum deviation. The technique we employ consists of additional dipoles, leading to the advantageous property that variability can be achieved without incurring significant penalty in terms of chromatic degradation. We show this by comparison to an alternative system where additional quadrupoles are utilised to enable variation of momentum compaction. Each of these alternative approaches are being considered in the context of an upgrade of the MAX IV linac, Sweden, to enable a soft X-ray free-electron laser (FEL) in addition to its existing functions., 9 pages

In recent decades traffic calming, especially in villages situated on through roads, has become an urgent issue. Various schemes are applied in the transition zones to reduce the inbound traffic speeds and thus improve the traffic safety. The studies conducted in several countries point to different determinants of the speed reduction obtained in this way. This article deals with the schemes including a central island horizontally deflecting one lane, located in transition zones to villages with 70 km/h speed restriction on two-lane roads (6 m carriageway width). In order to identify the speed reduction determinants, the speeds before and after chicanes were measured and the effect of the three criteria was investigated, characterising: the traffic management scheme, road design parameters, landscape elements present in the surroundings of the transition zone and visibility conditions. Based on the confirmation of logical tautology of many pre-selected factors, one aggregate parameter was proposed for the assessment of the practicable level of speed reduction, combining the effect of the selected factors in the above-mentioned criteria. Statistical analysis of the obtained results confirmed a statistically significant relationship between both the speed reduction value and the speed reduction index, and the aggregate parameter proposed by the authors. Factors related to the surrounding landscape and visibility conditions were found to have the greatest direct effect on speed reduction. The chicanes chosen in the final step of the proposed design process should be enhanced by additional solar-powered elements ensuring their improved visibility. These devices should not, however, require any additional energy supply and should not increase the construction or maintenance costs.

The ability to identify regulatory interactions that mediate gene expression changes through distal elements, such as risk loci, is transforming our understanding of how genomes are spatially organized and regulated. Capture Hi-C (CHi-C) is a powerful tool to delineate such regulatory interactions. However, primary analysis and downstream interpretation of CHi-C profiles remains challenging and relies on disparate tools with ad-hoc input/output formats and specific assumptions for statistical modeling. Here we present a data processing and interaction calling toolkit (CHiCANE), specialized for the analysis and meaningful interpretation of CHi-C assays. In this protocol, we demonstrate applications of CHiCANE to region capture Hi-C (rCHi-C) and promoter capture Hi-C (pCHi-C) libraries, followed by quality assessment of interaction peaks, as well as downstream analysis specific to rCHi-C and pCHi-C to aid functional interpretation. For a typical rCHi-C/pCHi-C dataset this protocol takes up to 3 d for users with a moderate understanding of R programming and statistical concepts, although this is dependent on dataset size and compute power available. CHiCANE is freely available at https://cran.r-project.org/web/packages/chicane .

Soft x-ray self-seeding has been proved to be a feasible method to improve the longitudinal coherence of high gain free-electron laser. However, a pedestal-like sideband in the spectrum has been observed in the experiment, which generally limits the purity of the radiation pulse and the user’s application. The previous theoretical study indicates that the pedestal-like sideband is mainly induced by microbunching instability generated from LINAC. In this paper, three dimensional simulations have been performed to confirm the analytical results and show the formation process of the spectral sideband. A probable method is proposed to eliminate the pedestal-like sideband by simply inserting a magnetic chicane before the self-seeding FEL undulator. Theoretical and numerical simulations have been performed and the results show that the proposed method can efficiently eliminate the microbunching-instability-induced sideband in a soft x-ray self-seeding FEL.

In this paper, ultrashort bunch length monitoring was demonstrated based on Terahertz (THz) coherent transition radiation (CTR) in Tsinghua Thomson scattering X-ray (TTX) source. The radiation produced by electron bunch is split into three paths: one of them is used to detect the total energy, while the other two paths are filtered with different THz band-pass filters before detection. The bunch length variation can be obtained by calculating the ratio between the filtered energy and the total energy. The bunch is compressed by a chicane and via changing the current of chicane, the ratio of filtered energy and total energy changed correspondingly. It is a simple supplemental approach to monitor the bunch length during beam conditioning and facility operation. Bunch arrival-time jitter and nonlinear effects in chicane are observed in the experiment during the measurement of filtered energy and total energy.

The heat transfer performance of a novel type trisection helical baffle vertical condenser was experimentally investigated. The testing schemes have a common shell and replaceable tube bundles, including six tube bundles with different structured trisection helical baffles and a segmental one. The investigation is aimed at revealing the impacts on the heat transfer performance of structural improvements for facilitating condensate drainage, including inclined helical baffles of variable angles, dual threads and bent tail edges. The experimental results show that the best scheme, which adopts dual thread variable angled baffles with bent tail edges, has the average shell side heat transfer coefficient 131.8% higher than that of the segmental one. Taking the shell side heat transfer coefficient as the evaluation index, the single thread variable angle schemes are on average 25.47% higher than the single thread fixed angle ones; the dual thread variable angle schemes are on average 15.74% higher than the single thread ones; and the schemes with bent tail edges are on average 6.37% higher than the corresponding ones without bent tail edges. The results give a prospective way to overcome the deficiency of inferior heat transfer performance of the conventional segmental baffled vertical condenser to that of the horizontal one.

The Free Electron Laser (FEL) application of Laser Plasma Acceleration (LPA) requires the handling of the energy spread and divergence. The COXINEL manipulation line, designed and built at SOLEIL for this purpose, consists of high gradient quadrupoles for divergence handling and a decompression chicane for energy sorting, enabling FEL amplification with baseline parameters. Installed at Laboratoire d’Optique Appliquee (LOA), it uses robust electrons generated and accelerated by ionization injection using a 30 TW laser. We report here on the work progress towards a FEL demonstration. The LPA measured electron beam characteristics deviates from the baseline reference case. After the installation of the equipment, the electron beam transport has first been optimized. The electron position and dispersion are independently adjusted. Then, undulator radiation has been measured. The spectral purity is controlled via the energy spread adjusted in the slit located in the chicane. FEL effect demonstration is within reach, with currently achieved performance on different LPA experiments.

The extreme electromagnetic fields sustained by plasma-based accelerators could drastically reduce the size and cost of future accelerator facilities. However, they are also an inherent source of correlated energy spread in the produced beams, which severely limits the usability of these devices. We propose here to split the acceleration process into two plasma stages joined by a magnetic chicane in which the energy correlation induced in the first stage is inverted such that it can be naturally compensated in the second. Simulations of a particular 1.5-m-long setup show that 5.5 GeV beams with relative energy spreads of $1.2\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}3}$ (total) and $2.8\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}4}$ (slice) could be achieved while preserving a submicron emittance. This is at least one order of magnitude below the current state of the art and would enable applications such as compact free-electron lasers.

Ambient ionization techniques provide a way to sample materials via creation of ions in the air. However, transferring and focusing of these ions is typically done in the reduced pressure environment of the mass spectrometer. Spray-based ambient ionization sources require relatively large distances between the source and mass spectrometer inlet for effective desolvation, resulting in a small fraction of the ions being collected. To increase the efficiency of ion transfer from atmosphere to vacuum, 3D-printed focusing devices made of conductive carbon nanotube doped polymers have been designed and evaluated for ion focusing in air. Three main classes of electrodes are considered: (i) conic section electrodes (conical, ellipsoidal, and cylindrical), (ii) simple conductive and non-conductive apertures, and (iii) electrodes with complex geometries (straight, chicane, and curved). Simulations of ion trajectories performed using the statistical diffusion simulation (SDS) model in SIMION showed a measure of agreement with experiment. Cross-sectional images of ion beams were captured using an ion detecting charge-coupled device (IonCCD). After optimization, the best arrangements of electrodes were coupled to an Agilent Ultivo triple quadrupole to record mass spectra. Observations suggest that electrode geometry strongly influences ion trajectories in air. Non-conductive electrodes also assisted in focusing, due to charge buildup from ion deposition. We also observed minimal spreading of the ion packet after exiting the focusing electrodes indicating that atmospheric collisions do not reduce collimation of the beam. The study suggests that high pressures need not be viewed as a hindrance to ion transport, but as a potentially useful force.

At SwissFEL, a fully non-invasive characterization of the beam energy distribution can be performed by means of a Synchrotron-Radiation-Monitor (SRM) imaging in the visible the transverse profile of the electron beam in a magnetic chicane. Under conditions of off-crest acceleration in the SwissFEL injector, according to a first order Taylor series expansion, the distribution of the relative energy of the electron beam can be linearly expressed as a function of the distribution of the electron longitudinal coordinates via the coefficient of the rf induced beam energy chirp. It is hence possible to express the distribution of the electron longitudinal coordinates at the entrance of the magnetic chicane of SwissFEL as a function of the distribution of the dispersed electron trajectories in the horizontal plane of the magnetic chicane. Machine parameters and instrument data at SwissFEL can be beam-synchronously acquired. A shot-by-shot correlation between the analysis results of the SRM camera images and the linear coefficient of the beam energy chirp resulting from the rf parameters of the injector can be hence established. Finally, taking into account the compression factor of the magnetic chicane, the electron bunch length at the exit of the magnetic chicane can be expressed as a function of the horizontal size of the electron beam imaged by the SRM. Bunch-length measurements performed by means of the SRM in the first magnetic chicane of SwissFEL will be presented.

Physical review accelerators and beams 22(3), 032401 (2019). doi:10.1103/PhysRevAccelBeams.22.032401, A study of the optimization of iron dominated dipole magnets with pole face widths comparable or less than the gap size, i.e., low aspect ratio (AR), is conducted using both theoretical and computational approaches. This regime of magnet design is particularly relevant in the context of laser plasma accelerators (LPA) due to unique beam parameters and geometric constraints, namely large energy spreads and the requirement for large apertures to accommodate drive laser passage. The breakdown of commonly employed approximations and rules of thumb in typical AR≫1 magnet design is examined. A library of generalized, optimized pole face geometries is provided to expedite optimization of future magnets. Finally, this methodology is used to design an electromagnetic chicane which has been fabricated, validated, and is currently in use in an x-ray free electron laser driven LPA experiment at LBNL., Published by American Physical Society, College Park, MD

A magnetic chicane bunch compressor for a new compact accelerator-based terahertz (THz) radiation source at the Institute of Advanced Energy, Kyoto University, was completely installed in March 2016. The chicane is employed to compress an electron bunch with an energy of 4.6 MeV generated by a 1.6-cell photocathode radio frequency (RF)-gun. The compressed bunch is injected into a short planar undulator for THz generation by coherent undulator radiation (CUR). The characteristics of the bunch compressor and the compressed bunch were investigated by observing the coherent transition radiation (CTR). The CTR spectra, which were analyzed by using a Michelson interferometer, and the compressed bunch length were also estimated. The results were that the chicane could compress the electron bunch at a laser injection phase less than 45 degrees, and the maximum CTR intensity was observed at a laser injection phase around 24 degrees. The optimum value of the first momentum compaction factor was around &minus, 45 mm, which provided an estimated rms bunch length less than 1 ps.

The Microbunched Electron Cooling (MBEC) is a promising cooling technique that can find applications in future hadron and electron-ion colliders to counteract intrabeam scattering that limits the maximum achievable luminosity of the collider. To minimize the cooling time, one would use amplification cascades consisting of a drift section followed by a magnetic chicane. In this paper, we first derive and optimize the gain factor in an amplification section for a simplified one-dimensional model of the beam. We then deduce the cooling rate of a system with one and two amplification cascades. We also analyze the noise effects that counteract the cooling process through the energy diffusion in the hadron beam. Our analytical formulas are confirmed by numerical simulations for a set of model parameters., arXiv admin note: text overlap with arXiv:1806.02785

A THz coherent undulator radiation (THz-CUR) source has been developed at the Institute of Advanced Energy, Kyoto University. A photocathode Radio-Frequency (RF) gun and a bunch compressor chicane are used for generating short-bunch electron beams. When the electron beam energy is low, the space-charge effect strongly degrades the beam quality, such as the bunch length and the energy spread at the high bunch charge condition at around 160 pC, and results in the reduction of the highest frequency and the maximum radiated power of the THz-CUR. To mitigate the space charge effect, we have investigated the dependence of the electron beam quality on the laser distribution in transverse and longitudinal directions by using a numerical simulation code, General Particle Tracer GPT. The manipulation of the laser distribution has potential for improving the performance of the THz-CUR source. The electron bunch was effectively compressed with the chicane magnet when the laser transverse distribution was the truncated Gaussian profile, illuminating a cathode. Moreover, the compressed electron bunch was shortened by enlarging the laser pulse width. Consequently, an enhancement of the radiated power of the THz-CUR has been indicated.