Transport Of Bunches Research Articles

Design and Experimental Study of Banana Bunch Transportation Device with Lifting Mechanism and Automatic Bottom-Fixing Fruit Shaft

In addressing the challenges of high labor intensity, cost, and potential mechanical damage to banana fruit in orchards, this study presents the design of a banana bunch transport device featuring a lifting mechanism and an automatic fruit shaft bottom-fixing system. The device is tailored to the planting and morphological characteristics of banana bunches, aiming for efficient, low-loss, and labor-saving mechanized transport. Key design considerations included the anti-overturning mechanism and the lifting system based on transportation conditions and the physical dimensions of banana bunches. A dynamic simulation was conducted to analyze the angular velocity and acceleration during the initial conveying stages, forming the basis for the fruit shaft bottom-fixation mechanism. A novel horizontal multi-point scanning method was developed to accurately identify and secure the fruit shaft bottom, complemented by an automated control system. Experimental results showed a 95.83% success rate in identification and fixation, validated by field trials that confirmed the necessity and stability of the fixation mechanism. To enhance the durability of the fruit shaft bottom-fixation mechanism, a multi-factor test was conducted, optimizing the device’s maximum travel speed and minimizing the banana bunch’s oscillation angle. Field tests showed an oscillation angle of 8.961°, closely matching the simulated result of 9.526°, demonstrating the reliability of the response surface analysis model. This study offers a practical and efficient solution for banana bunch transport in orchards, showcasing significant practical value and potential for wider adoption.

The effect of transport apertures on relay-imaged, sharp-edged laser profiles in photoinjectors and the impact on electron beam properties

In a photoinjector electron source, the initial transverse electron bunch properties are determined by the spatial properties of the laser beam on the photocathode. Spatial shaping of the laser is commonly achieved by relay imaging an illuminated circular mask onto the photocathode. However, the Gibbs phenomenon shows that recreating the sharp edge and discontinuity of the cut profile at the mask on the cathode is not possible with an optical relay of finite aperture. Furthermore, the practical injection of the laser into the photoinjector results in the beam passing through small or asymmetrically positioned apertures. This work uses wavefront propagation to show how the transport apertures cause ripple structures to appear in the transverse laser profile even when effectively the full laser power is transmitted. The impact of these structures on the propagated electron bunch has also been studied with electron bunches of high and low charge density. With high charge density, the ripples in the initial charge distribution rapidly wash-out through space charge effects. However, for bunches with low charge density, the ripples can persist through the bunch transport. Although statistical properties of the electron bunch in the cases studied are not greatly affected, there is the potential for the distorted electron bunch to negatively impact machine performance. Therefore, these effects should be considered in the design phase of accelerators using photoinjectors.

A beamline to control longitudinal phase space whilst transporting laser wakefield accelerated electrons to an undulator

Laser wakefield accelerators (LWFAs) can produce high-energy electron bunches in short distances. Successfully coupling these sources with undulators has the potential to form an LWFA-driven free-electron laser (FEL), providing high-intensity short-wavelength radiation. Electron bunches produced from LWFAs have a correlated distribution in longitudinal phase space: a chirp. However, both LWFAs and FELs have strict parameter requirements. The bunch chirp created using ideal LWFA parameters may not suit the FEL; for example, a chirp can reduce the high peak current required for free-electron lasing. We, therefore, design a flexible beamline that can accept either positively or negatively chirped LWFA bunches and adjust the chirp during transport to an undulator. We have used the accelerator design program MAD8 to design a beamline in stages, and to track particle bunches. The final beamline design can produce ambidirectional values of longitudinal dispersion (R_{56}): we demonstrate values of + 0.20 mm, 0.00 mm and − 0.22 mm. Positive or negative values of R_{56} apply a shear forward or backward in the longitudinal phase space of the electron bunch, which provides control of the bunch chirp. This chirp control during the bunch transport gives an additional free parameter and marks a new approach to matching future LWFA-driven FELs.

Toward a Laser-Driven Traveling-Wave Linac on a Chip

Restricted by pulse dispersion, dephasing, and bunch deflection, it has been a challenging task to realize high-gain particle acceleration and bunch focusing by using an ultrashort-pulse laser to drive an integrable acceleration structure, which is necessary to develop an on-chip particle accelerator for practical applications. Here we propose a laser-driven traveling-wave linac (linear accelerator), which uses the cascade reflection and refraction of an ultrashort laser pulse on a microscale dielectric structure to achieve long-range laser-particle interaction, avoiding waveguide dispersion, and enhancing sustainable acceleration gradient. It is scalable and extensible, and can realize full-course particle acceleration by using a single laser source via the inverse Cherenkov effect. With this accelerator scheme, we further propose a dynamic synchronization and focusing method, which not only counteracts dephasing but also restrains the bunch spread and deflection caused by space-charge and emittance effects, realizing stable bunch transport and acceleration in a tiny-size bunch channel without resorting to the need for external focusing equipment. This accelerator scheme paves the way toward a high-efficiency laser-driven all-dielectric on-chip particle accelerator for practical applications.

Theory of wakefields excited by an off-axis drive bunch in a plasma–dielectric waveguide

A linear theory of wakefield excitation by a drive electron bunch in a plasma–dielectric accelerating structure has been constructed for the case of off-axis bunch injection. The structure under investigation is a round dielectric-loaded metal waveguide with a channel for charged particles, filled with homogeneous cold plasma. The developed theory was used to investigate the spatial distribution of the bunch-excited transverse wakefield components, which act on the drive electron bunch. The numerical simulations using the particle-in-cell method have confirmed the predictions of the linear theory in terms of transverse drive bunch dynamics. The numerical analysis has shown stable drive bunch transport through the plasma–dielectric accelerating structure compared with the corresponding dielectric-loaded structure.

Development of mobile-based apps for oil palm fresh fruit bunch transport monitoring system

After being harvested, the oil palm fresh fruit bunch (FFB) has to be evacuated from the field and transported to the oil palm mill. In most cases, it transported using the trucks. FFB transportation should be optimized in order to achieve the best FFB quality and minimum cost. This research was aimed to develop tools to monitor trucks as FFB transport equipment, due to some deviations in the field. The Development of the application using these method: business process analysis, system analysis, system design, and implementation and functional test. The application software run as an Android-based application, as a map-based application, and using location-based service. The system also runs as a web-based application and has been tested on FFB logistic system in private plantation company. It monitored the truck route and FFB loading and transporting activities in the field, as well as gave instruction to the truck driver in order to avoid the heavy queue in an oil palm mill.

Transport and analysis of electron beams from a laser wakefield accelerator in the 100 MeV energy range with a dedicated magnetic line

Electron bunches generated by laser driven wakefield acceleration are transported and analyzed using a magnetic line composed of a triplet of quadrupoles and a dipole. Short pulse bunches with a total charge of ≈130pC, and broad band energy spectra in the range 45 to 150MeV are generated by ionization assisted injection in a gas cell. The electron source is imaged about one meter away from the exit of the gas cell by the magnetic line, delivering electron bunches at a stable position in the image plane where a charge density of ≈2.9pC∕mm2 at an energy of 69.4±0.6MeV is achieved. This magnetic line improves dramatically the accuracy of energy determination of this electron source, leading to an energy error as low as 8.6‰ in the 70MeV range for 5mrad divergence electron bunch and considering the resolution of the entire detection system. The transport of bunches with improved stability and energy selection paves the way to various applications including multi-stage laser plasma acceleration.

Carbon footprint of the production of oil palm (Elaeis guineensis) fresh fruit bunches in Colombia

Oil palm is the major source of vegetable oil in the world, produced mainly by Malaysia and Indonesia. Colombia is the second largest producer outside Southeast Asia and the largest producer in South and Central America. The expansion of oil palm crop in Colombia has a great potential for reducing greenhouse gas emissions, because it is planted in areas covered by low biomass vegetation. The first step for reducing these greenhouse gas emissions is to quantify them, and the carbon footprint is the algebraic sum of the greenhouse gas sequestration and emissions caused directly or indirectly by an individual, organization or product for a defined period of time. For that, the objective of this study was to determine the carbon footprint of the crop stage, i.e of production of oil palm fresh fruit bunches in an experimental field, representative of a well managed plantation in Colombia. Following the Colombian Technical Standard NTC 6000, one ton of oil palm fresh fruit bunches was established as a functional unit; inputs, activities and processes directly or indirectly involved in the production of oil palm fresh fruit bunches were inventoried, and the carbon footprint balance between sequestration and greenhouse gas emissions was estimated using the Ecoinvent database and emission factors of the SimaPro 7.0 software. CO2 capture by the crop was higher than greenhouse gas emissions associated: for each ton of oil palm fresh fruit bunches produced, 606 kg of CO2 were fixed. N2O was the most significant greenhouse gas emitted during the crop stage, and the activities in descending order that contributed most to the greenhouse gas emissions were the use of chemical nitrogen fertilizers, transport of bunches to the processing plant, land use change and the energy used in transport and tractor traction. Since carbon footprint is a benchmark for internal management or mitigation of greenhouse gas emissions, a mitigation plan was drawn up to improve the carbon balance, by increasing the use of organic fertilizers: planting oil palms on degraded land or with low biomass accumulation; using oil palm biodiesel as a substitute for fossil fuels; improving the yield of oil palm fresh fruit bunches through increased production efficiency; and by producing biochar at the time of replanting. These integrated strategies that in descending order have different effects into the carbon balance could increase the eco-efficiency of the oil palm in terms of carbon sequestration for Colombian oil palm agribusiness.

Simulation of Laser-Accelerated Proton Focusing and Diagnosis with a Permanent Magnet Quadrupole Triplet

(Received 10 January 2010 /Accepted 19 January 2010)The Monte Carlo Particle and Heavy Ion Transport code (PHITS) was used for diagnosing the focusingand defocusing action of a triplet of permanent magnet quadrupoles on laser-accelerated proton bunches of shortduration. ThecodepredictsreasonablywelltheobservedtransversebeamprofileasmeasuredwithaCR-39trackdetector demonstrating that PHITS can be used to simulate proton bunch transport by conventional ion optics inthe laser-driven case.