Physical design of a new set of high poloidal mode number coils in the EAST tokamak

An external resonant magnetic perturbation (RMP) field, an effective method to mitigate or suppress the edge localized mode (ELM), has been planned to be applied on the ELM control issue in ITER. A new set of magnetic perturbation coils, named as high m coils, has been developed for the EAST tokamak. The magnetic perturbation field of the high m coils is localized in the midplane of the low field side (LFS), with a spectrum characteristic of high m and wide n, where m and n are the poloidal and toroidal mode numbers, respectively. The high m coils generates a strong localized perturbation field. Edge magnetic topology under the application of high m coils should have either a small or no stochastic region. With the combination of the high m coils and the current RMP coils, flexible working scenarios of the magnetic perturbation field are available, which is beneficial for ELM control exploration on EAST. Numerical simulations have been carried out to characterize the high m coil system, including the magnetic spectrum and magnetic topology, which shows a great flexibility of magnetic perturbation variation as a tool to investigate the interaction between ELM and external magnetic perturbation.

Zero-field skyrmionic states and in-field edge-skyrmions induced by boundary tuning

When magnetic skyrmions are moved via currents, they do not strictly travel along the path of the current, instead their motion also gains a transverse component. This so-called skyrmion Hall effect can be detrimental in potential skyrmion devices because it drives skyrmions towards the edge of their hosting material where they face potential annihilation. Here we experimentally modify a skyrmion model system—an atomic Pd/Fe bilayer on Ir(111)—by decorating the film edge with ferromagnetic Co/Fe patches. Employing spin-polarized scanning tunneling microscopy, we demonstrate that this ferromagnetic rim prevents skyrmion annihilation at the film edge and stabilizes skyrmions and target states in zero field. Furthermore, in an external magnetic field the Co/Fe rim can give rise to skyrmions pinned to the film edge. Spin dynamics simulations reveal how a combination of different attractive and repulsive skyrmion-edge interactions can induce such an edge-pinning effect for skyrmions.

Comparative Indicators of Grain Transportation When Unloading Combine Harvesters at the the Field Edge

Base don theresults of comparative experience in production conditions, the indicators of grain transportation by trucks were determined when unloading combine harvesters at the field edge.

Botanical and mineral composition of dominant wild forages for feeding of dairy goats in Payakumbuh Region

The objectives of this study were (i) to identify the diversity of forages that are usually consumed or fed to the dairy goats, (ii) to assess the mineral composition of dominant forages concerning the soil mineral status of growing areas. Eight dairy goat farms surveyed and collected forage samples to define the diversity and dominant forages used to feed the goat. Samples of three dominant forages (Asystasia gangetica, Axonopus compressus, and Panicum maximum) and soils were then collected in five different areas where the farmers usually derived the forages (banana plantation, idle lands, riverbanks, roadside, and rice field edge). Plant samples were collected by using a plate meter used for the calculation of botanical composition. Fresh samples were then chopped, dried, and then ground in meal form before analysis for dry matter (DM), and minerals of Ca, P, Mg, K, Na, and S. The same minerals were analyzed for soil samples. Data were subjected to analysis of variance (ANOVA) in a completely randomized design of 5x3 consisting of 3 plant species and five growing areas as replications. Data were statistically analyzed using correlation and variance analysis in Random Block Design (RBD). Results showed of the total about 45 types of plants commonly consumed by goats, there were three dominant species, i.e., P. maximum (38.60%), A. gangetica (24.23%), and A. compressus (17.23%). The Ca content of forages highly correlated with the Ca in the soils, while magnesium in the forage was negatively correlated with the magnesium in the soil. It was concluded that the dominant forages were found a good source of Ca and Mg but deficient phosphorus.

Electron and Photon Energy Spectra Outside of 6 MV X-ray Small Radiotherapy Field Edges Produced by a Varian iX Linac

Due to the increase in the survival probability for patients treated with modern radiotherapy techniques to live enough for experimenting the late radiation effect, low dose outside the treatment volume becomes a concern. However, besides the absorbed dose, the beam quality outside the field edge should be taken into account. This work aimed at investigating the photon and electron fluence spectra outside the field edges for several small radiotherapy fields for determining the quality of the beams in order to better evaluate the secondary effect after modern radiotherapy treatments. Phase-space files of a 6 MV X-ray beam produced by a Varian iX linac for eight small fields of 0.7 × 0.7 cm2, 0.9 × 0.9 cm2, 1.8 × 1.8 cm2, 2.2 × 2.2 cm2, 2.7 × 2.7 cm2, 3.1 × 3.1 cm2, 3.6 × 3.6 cm2, and 4.5 × 4.5 cm2 and for the reference 10 × 10 cm2 field at SSD = 100 cm were generated using the BEAMnrc code. The photon and electron fluences in each field were calculated at 0.15, 1.35, and 9.85 cm water depth and several off-axis distances using FLURZnrc. The number of low-energy electrons between 1 and 10 keV at 2 cm outside the field edge increases by 60% compared to the central axis. Due to the relatively high linear energy transfer (LET) of these electrons, the results of this work should help to better evaluate the possible late effect of secondary radiation on healthy organs close to the tumor volume after radiotherapy treatment. We also observed high-energy electrons outside the field edge that are attributed to the leakage of the primary electron beam from the head of the linac. From a standpoint of radiological protection, these electrons should be taken into account when evaluating the dose delivered to the patient’s skin.

Comparative Performance of Grain Harvesters in Case of Unloading Grain at the Field Edge

The results of a combine harvester comparative performance assessment using a new method in the case of unloading grain at the field edge have been determined.

Evaluation of a new foetal shielding device for pregnant brain tumour patients

Background The present study aimed to propose a new foetal shielding device for pregnant cancer patients to reduce the foetal dose associated with treatment techniques using multiple gantry angles, such as intensity-modulated radiation therapy (IMRT) or volumetric modulated arc therapy (VMAT). Methods Three shielding structures were designed to minimise the scattered and leaked radiation from various gantry angles and radiation scattering within the patient. The base-plate part that can be placed on the treatment couch was designed to reduce the scattered and leaked radiation generated at gantry angles located near 180°. A body shielding part that can cover the lower chest and abdomen was designed, and a neck-shielding structure was added to reduce the internal and external radiation scattering from the treatment area. Evaluation plans were generated to assess the foetal dose reduction by the foetal shielding device in terms of the shielding material thickness, distance from the field edge, and shielding component using the flattened 6 MV photon beam (6MV) and flattening filter-free 6 MV photon beam (6MV-FFF). In addition, the effectiveness of the foetal shielding device was evaluated in a pregnant brain tumour patient. Results The shielding material consisting of three parts was placed on frames composed of four arch shapes with a vertical curved structure, connection bar at the top position, and base plate. Each shielding part resulted in reductions in the radiation dose according to the treatment technique, as the thickness of the shielding material increased and the foetal dose decreased. In addition, a foetal dose reduction of approximately 50% was confirmed at 50 cm from the field edge by using the designed shielding device in most delivery techniques. In patients, the newly designed shielding structures can effectively eliminate up to about 49% of the foetal dose generated from various gantry angles used in VMAT or IMRT. Conclusions We designed a foetal shielding device consisting of three parts to effectively reduce the dose delivered to the foetus, and evaluated the device with various treatment techniques for a pregnant patient with brain tumour. The foetal shielding device shielded the scattered/leaked radiation from the treatment machine, and also effectively reduced internal scattering from the treatment area in the patient.