Orbit Width Research Articles

The role of fast ions in spontaneous neoclassical tearing mode instabilities in NSTX

Spontaneous neoclassical tearing modes (spontaneous NTMs) have been observed in the National Spherical Torus Experiment (NSTX). Recently, a TRANSP based model for the modified Rutherford equation analysis was developed to accurately predict the effect of fast ions on the growth of magnetic islands. The goal of this paper is to utilize the TRANSP NTM model to understand the role of fast ions in NSTX spontaneous NTMs. Our analysis shows that when the passing fast ion driven kinetic neoclassical polarization current term is larger than 1% of the bootstrap current term in the modified Rutherford equation, fast ions play a decisive role in the early growth phase of spontaneous NTM. This result is applicable to any tokamak plasmas with a fast ion drift orbit width, or the fast ion poloidal Larmor radius, comparable to the magnetic island width.

Distinguishing between regular and chaotic orbits of flows by the weighted Birkhoff average

This paper investigates the utility of the weighted Birkhoff average (WBA) for distinguishing between regular and chaotic orbits of flows, extending previous results that applied the WBA to maps. It is shown that the WBA can be super-convergent for flows when the dynamics and phase space function are smooth, and the dynamics is conjugate to a rigid rotation with Diophantine rotation vector. The dependence of the accuracy of the average on orbit length and width of the weight function width are investigated. In practice, the average achieves machine precision of the rotation frequency of quasiperiodic orbits for an integration time of O(103) periods. The contrasting, relatively slow convergence for chaotic trajectories allows an efficient discrimination criterion. Three example systems are studied: a two-wave Hamiltonian system, a quasiperiodically forced, dissipative system that has a strange attractor with no positive Lyapunov exponents, and a model for magnetic field line flow.

Magnificent Harmony in Morphometric Measurements of Orbita and Foramen Magnum

The foramen magnum (FM) is the key component of the craniovertebral junction, which connects the brain stem and medulla spinalis and is closely related to vital structures. FM dimensions are of great clinical importance. Considering the similarity in shape between FM and orbita, we thought that there might be a relationship between the lengths (sagittal diameter) and widths (transverse diameter) of these structures. Since it is not possible to reach FM directly, we set up our hypothesis as can we calculate the foramen magnum dimensions from orbital measurements before proceeding to costly tests. We also investigated this harmony in the skulls we used in the study. In the study, 21 dried skull bones from the Turkish population were used. FM and right Orbital length and width measurements were made. Precision digital caliper was used for measurements. Statistical validity and reliability analyzes were performed to prove the agreement between the measurements. We found that the length of the orbit and FM in the sagittal plane is close to each other, with 34.74±2.11 mm and 34.99±3.0 mm, and the width of the orbit in the coronal plane is approximately 1.40 times the width of the FM. We proved that the estimation of FM dimensions based on orbital measurements is also statistically valid and safe. Using orbital measurements, it is possible to estimate FM dimensions which are difficult to reach directly in living humans.

Super-Fermi acceleration in multiscale MHD reconnection

We investigate the Fermi acceleration of charged particles in 2D MHD anti-parallel plasmoid reconnection, finding a drastic enhancement in energization rate ε ̇ over a standard Fermi model of ε ̇ ∼ ε. The shrinking particle orbit width around a magnetic island due to E → × B → drift produces a ε ̇ ∥ ∼ ε ∥ 1 + 1 / 2 χ power law with χ ∼ 0.75. The increase in the maximum possible energy gain of a particle within a plasmoid due to the enhanced efficiency increases with the plasmoid size and is by multiple factors of 10 in the case of solar flares and much more for larger plasmas. Including the effects of the non-constant E → × B → drift rates leads to further variation in power law indices from ≳ 2 to ≲ 1, decreasing with plasmoid size at the time of injection. The implications for energetic particle spectra are discussed alongside applications to 3D plasmoid reconnection and the effects of a guide field.

Difference of anterior and posterior orbital development in patients with congenital microphthalmia: a retrospective cohort study from China

To evaluate volume differences between anterior and posterior orbit and demographic characteristics of Chinese patients with congenital microphthalmia. A retrospective cohort study, involving 169 unilateral congenital microphthalmia patients aged between 1 and 57 years old was conducted. Three-dimensional images of the orbit were generated from past CT scans, and digital orbital volume comprehensive measurement was done. The measured data included orbital volume (OBV), posterior orbital volume (POV), orbital width (OBW), orbital height (OBH), orbital depth (OBD), and posterior orbital area ratio. Significant differences were observed among OBV, POV, OBW, OBH, and OBD of the affected and unaffected eyes in different age-based groups (all P<0.001). Among them, OBH had the greatest different. The mean microphthalmic to contralateral ratio (MCR) of OBV, POV, OBW, and OBH continuously increased from 1 to 3 years old, whereas the MCR of POV decreased from 3 to 17 years old. The MCR of OBD was not found to be correlated to age. There was no significant difference between OBV, POV, OBW, and OBH in ages from 13 years old to adulthood (all P>0.05). The difference in posterior orbital area ratio between the affected and unaffected groups was not statistically significant (P>0.05). OBH is maximally affected, whereas OBD is minimally affected by microphthalmia. Posterior orbital retardation began 2y prior to orbital retardation and occurred at 3 years old in the affected eye, suggesting that intervention therapy should be done before the age of 4.

“EVALUATION OF FRONTAL SINUS AS AN AID IN PERSONAL IDENTIFICATIONA DIGITAL RADIOGRAPHIC STUDY”

Background And Objectives: The cranio-facial structures have the advantage of being composed largely of hard tissue which is relatively indestructible. The frontal sinus is as unique to each individual as a ngerprint, even to monozygotic twins. The present study was conducted to evaluate frontal sinus as an aid in personal identication. The study was conducted among 200 subjects (100 males and 100 females). P Methods: osteroanterior radiographs were taken using KODAK 8000 C Digital Panoramic and Cephalometric system and digital measurements made using Trophy Dicom and Masterview 3.0 Software. Frontal sinuses were classied and analyzed as per Yoshino, Cameriere, Tang et al's methods. Total height and total width of frontal sinus was measured according to Tatlisumak and Uthman A T. Inter orbital width was measured according to Ribeiro. Total orbital width was measured as an additional parameter. Of the Results: total 200 (100%) subjects we observed uniqueness of frontal sinuses in all the 167 subjects with presence of frontal sinus with central septa presence with none being identical and found 16 subjects with central septa absence, where the mean total height and total width of frontal sinus was measured and 17 subjects with bilateral absence of frontal sinus, where mean inter-orbital width was measured. Total orbital width was considered for the combined 33 subjects. We conclude that frontal Conclusion: sinuses can be used as a potent aid in personal identication. The combined use of frontal sinus and orbital measurements can be a valuable, cost-effective adjunct to positive human identication.

Non-monotonic radial structures of fluctuating temperatures and densities associated with fishbone activities in KSTAR

General characteristics of a fishbone mode in KSTAR are investigated. Fishbone activities are observed with a Mirnov coil, an electron cyclotron emission radiometer (from the core to the edge of plasmas) and an beam emission spectroscopy system (core or edge plasmas) which are measuring fluctuations of poloidal magnetic fields, electron temperatures, and densities, respectively. Temporal evolutions of these fluctuations are similar to the observations from other tokamaks. An interesting and notable feature found in KSTAR fishbone modes is that radial coherence structures of electron temperature and density with respect to magnetic fluctuations are non-monotonic that they have a local minimum at r/a∼0.7 and a maximum at r/a∼0.9 in addition to the usual global peak near the q = 1 surface, where r/a is the normalized minor radius and q is the safety factor. Furthermore, the associated temporal evolution of the electron temperatures in slow-time scale, i.e., less than 1 kHz, with the fishbone activities show that there exist a drop in temperature or increase in temperature depending on inside or outside the q = 1 surface, respectively, from the core to the edge plasmas except that there are almost no temperature changes in the intermediate region which seems to be correlated with the non-monotonic coherence profile. Such a non-monotonic structure and the slow temporal evolution of temperatures are explained with barely trapped resonating fast ions with the banana orbit widths of the order of the minor radius, so that they transit the core and the edge regions simultaneously without trespassing the mid-plane intermediate region.

Morphometric and volumetric evaluations of orbit using three-dimensional computed tomography in southwestern Iranian population

BackgroundThe aim of the present research was to assess morphometric and volumetric measurements of bony orbit using computed tomography to define the effects of age and gender on orbital anthropometry. Method302 orbital cavities in 151 adult samples (18–90 years with a mean age of 43.10 ± 20.25 years) were investigated (100 males [66.2%] and 51 females [33.8%]). The samples represented no history of orbital trauma, dysplasia, or other diseases with a putative effect on orbital growth. ResultsThe mean orbital height for the right and left sides were 3.75 ± 0.20 and 3.74 ± 0.21 cm, respectively, while the orbital width was 3.44 ± 0.17 and 3.46 ± 0.17 cm, respectively. The mean interorbital-biorbital width was 2.26 ± 0.26 and 9.55 ± 0.41 cm, respectively. The mean OI in both genders was 108.52 ± 6.83. There was no significant difference in OI index between the genders or sides. The study population belonged to the Megaseme category. The mean right/left orbital volume (OV) of both genders was 25.20 and 24.68 cm3, respectively. OV was significantly larger in males than females (P < 0.005) and showed sexual dimorphism. There was a positive, statistically significant association of OV with the samples' age (P < 0.0001) ConclusionThe outcomes of this research showed that the CT and 3D volumetric methods represent useful baseline morphometric data for the southwestern Iranian population using a reliable technique in orbital volumetry. The obtained data can be used for the diagnosis of orbital pathologies and anthropological studies.

Gender Determination by Orbital Aperture Morphometry in Nalgonda Population

Background: The orbital aperture morphometry can be considered as a valuable tool in gender determination since orbit possesses resistance to damage and disintegration processes. Aim and Objective: The aim and objective of this study was to evaluate the orbital aperture dimensions in nalgonda population and verify their relationship with gender. Materials and Methods: The present retrospective study was conducted to evaluate the morphometric dimensions of orbital aperture seen on digital orthopantomogram taken using PLANMECA digital machine and ROMEXIS software. The height and width of the orbits were measured using measuring tools in the accompanying software. Data were analyzed using IBM SPSS Statistics for Windows, Version 23.0. Armonk, NY: IBM Corp. Results: Linear measurements such as orbital height and orbital width, were significantly greater in males than females in the Nalgonda population with P &lt; 0.001. The present study found 85.6% accuracy after subjecting the obtained value to discriminant function analysis. Conclusion: The discriminant scores greater than 1.5 value indicate the sample as male and scores lesser than 1.5 value indicate the sample as female. Therefore, orbital aperture measurements can be used for gender determination in human identification.

Morphometry of Skulls from North Indian Population

Introduction: Anthropometric studies have shown significant variations in the cranium and orbits between races and genders due to various factors such as genetics, race, hormones, nutritional differences, and environmental influences. The present study aims to record cranial and orbital dimensions and indices to classify skulls based on these measurements. Materials and Methods: Thirty-five human adult skulls were obtained from the dissecting laboratory and museum of Hind Institute of Medical Sciences, Safedabad. The orbital height, width, interorbital distance, maximum length, and width of the cranium were measured directly using a digital Vernier caliper. The skulls were then classified based on the orbital and cranial indices calculated. Results: The study found a mean orbital index of 83.42, classifying the skulls as mesoseme, and a cranial index of 73.15, classifying them as dolichocephalic. Conclusion: Basic data and records of morphometry of bones belonging to specific regions can help identify the ethnicity and race of a person. Understanding the correlation of dimensions of the orbital cavity and cranium is crucial in certain conditions, such as interpreting fossils, classification of skulls in forensic medicine, and discovering trends in evolution and racial differences. These findings may also aid in identifying unclaimed bodies in India, which are found in significant numbers yearly.

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The high-energy &lt;i&gt;α&lt;/i&gt; particles produced by deuterium-tritium fusion are the primary heating source for maintaining high temperatures in future tokamak plasma. Effective confinement of &lt;i&gt;α&lt;/i&gt; particles is crucial for sustaining steady-state burning plasma. The initial energy of &lt;i&gt;α&lt;/i&gt; particles is &lt;inline-formula&gt;&lt;tex-math id="M1"&gt;\begin{document}$ 3.5 {\text{ MeV}} $\end{document}&lt;/tex-math&gt;&lt;alternatives&gt;&lt;graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="21-20230700_M1.jpg"/&gt;&lt;graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="21-20230700_M1.png"/&gt;&lt;/alternatives&gt;&lt;/inline-formula&gt;. According to theoretical calculations, it takes approximately 1 second to slow down &lt;i&gt;α&lt;/i&gt; particles through Coulomb collisions to an energy range similar to the energy range of the background plasma. In the slowing-down process, some &lt;i&gt;α&lt;/i&gt; particles may be lost owing to various transport processes. One significant research problem is how to utilize &lt;i&gt;α&lt;/i&gt; particles to effectively heat fuel ions so as to sustain fusion reactions in a reactor. Assuming local Coulomb collisions and neglecting orbital effects, a classical slowing-down distribution for &lt;i&gt;α&lt;/i&gt; particles can be derived. However, considering the substantial drift orbit width of &lt;i&gt;α&lt;/i&gt; particles and the importance of spatial transport, numerical calculations are required to obtain more accurate &lt;i&gt;α&lt;/i&gt; particle distribution function. In this study, the particle tracer code (PTC) is used to numerically simulate the slowing-down process of &lt;i&gt;α&lt;/i&gt; particles under different scenarios in the Chinese Fusion Engineering Test Reactor (CFETR). By combining particle orbit tracing method with Monte Carlo collision method, a more realistic &lt;i&gt;α&lt;/i&gt; particle distribution function can be obtained and compared with the classical slowing-down distribution. The results show significant differences between this distribution function and the classical slowing-down distribution, particularly in the moderate energy range. Further analysis indicates that these disparities are primarily caused by the strong radial transport of &lt;i&gt;α&lt;/i&gt; particles at these energy levels. The research findings hold profound implications for the precise evaluating of ability of &lt;i&gt;α&lt;/i&gt; particles to heat the background plasma. Understanding and characterizing the behavior of &lt;i&gt;α&lt;/i&gt; particles in the slowing-down process and their interaction with the plasma is critical for designing and optimizing future fusion reactors. By attaining a deeper comprehension of the spatial transport and distribution of &lt;i&gt;α&lt;/i&gt; particles, it becomes possible to enhance the efficiency of fuel ion heating and sustain fusion reactions more effectively. This study establishes a foundation for subsequent investigations and evaluation of &lt;i&gt;α&lt;/i&gt; particles as a highly efficient heating source for fusion plasmas.

Drift kinetic theory of the NTM magnetic islands in a finite beta general geometry tokamak plasma

In (Imada et al 2019 Nucl. Fusion 59 046016 and references therein) a new 4D drift kinetic nonlinear theory, valid in the limit of a low beta, small inverse aspect ratio, circular cross section, toroidal geometry, to describe the plasma response to the neoclassical tearing mode (NTM) magnetic perturbation is derived. In (Dudkovskaia et al 2021 Plasma Phys. Control. Fusion 63 054001) this theory is reduced in a low collisionality limit, which allows a dimensionality reduction to a 3D problem to efficiently resolve the collisional dissipation layer in the vicinity of the trapped-passing boundary. (Dudkovskaia et al 2021 Plasma Phys. Control. Fusion 63 054001) adopts an improved model for the magnetic drift frequency, which reduces the threshold magnetic island half-width from , where is the trapped ion banana orbit width, to , making it in closer agreement with experimental observations for the large aspect ratio tokamak equilibrium. In the present paper, the theory is extended to a high beta, arbitrary tokamak geometry to capture the plasma shaping effects on the NTM threshold physics with the focus on the non-zero triangularity discharges that are known to have a strong impact on the plasma MHD stability. First, it is found that the higher triangularity plasma is more prone to NTMs which is in agreement with the tearing mode onset relative frequency measurements in DIII-D. Second, the NTM threshold dependence on the tokamak inverse aspect ratio obtained in (Dudkovskaia et al 2021 Plasma Phys. Control. Fusion 63 054001) is refined and extended to a finite aspect ratio limit. Third, the NTM threshold dependence on poloidal beta is obtained and benchmarked against the EAST threshold island width measurements.

Technical considerations of computer-aided planning in severe orbital trauma: A retrospective study

The aim of this study was to evaluate the clinical outcomes of linear and orbital volume measurements in severe orbital trauma. Patients with severe orbital trauma that involved more than two walls and entailed a marked degree of comminution were included in this retrospective analysis. However, patients with incomplete clinical records and a simple blowout or zygmatico-orbital fractures were excluded. All the cases underwent surgical correction guided by virtual surgical planning and 3D-printed templates. The measurement protocol depended on assessing orbital dimensions, orbital volumetry, and the zygomatic bone's position in the three-dimensional planes. All patients' preoperative 3D CT scans were obtained, and DICOM files were imported into a three-dimensional image processing software. Data were then converted for 3D reconstruction in the axial, coronal, and sagittal views. A total of 18 patients with a mean age was 39.28 ± 6.28 were included in this study. The results revealed a significant difference between the pre and postoperative differences in distances in relation to the FHP (Frankfurt Horizontal Plane) (P = 0.0014) and sagittal planes (P < 0.0001). The orbital width and height of the traumatized orbit were significantly decreased from 45.26 ± 6.72 mm and 45.30 ± 2.89 mm to 39.74 ± 3.91 mm (P = 0.0022), and 40.34 ± 0.86 mm (P < 0.0001), respectively. Clinically, there was a satisfactory degree of symmetry regarding the zygomatic bones' position and orbital dimensions postoperatively. Moreover, the mean orbital volume on the traumatized side decreased significantly from 23.16 ± 1.91 cm3 preoperatively to 20.7 ± 1.96 cm3 postoperatively (P < 0.0001). These findings were associated with a low incidence of complications. Within the limitations of the study it seems that the described methodology is a relevant addition to clinical treatment options. It incorporates all the latest technology to plan virtual reconstruction surgery in the treatment of complex orbital trauma and should be adapted accordingly in cases of severe displacement and comminution.

Energetic particle loss mechanisms in reactor-scale equilibria close to quasisymmetry

Collisionless physics primarily determines the transport of fusion-born alpha particles in 3D equilibria. Several transport mechanisms have been implicated in stellarator configurations, including stochastic diffusion due to class transitions, ripple trapping, and banana drift-convective orbits. Given the guiding center dynamics in a set of six quasihelical and quasiaxisymmetric equilibria, we perform a classification of trapping states and transport mechanisms. In addition to banana drift convection and ripple transport, we observe substantial non-conservation of the parallel adiabatic invariant which can cause losses through diffusive banana tip motion. Furthermore, many lost trajectories undergo transitions between trapping classes on longer time scales, either with periodic or irregular behavior. We discuss possible optimization strategies for each of the relevant transport mechanisms. We perform a comparison between fast ion losses and metrics for the prevalence of mechanisms such as banana-drift convection (Velasco et al 2021 Nucl. Fusion 61 116059), transitioning orbits, and wide orbit widths. Quasihelical configurations are found to have natural protection against ripple-trapping and diffusive banana tip motion leading to a reduction in prompt losses.

Finite orbit width effects in large aspect ratio stellarators

New orbit-averaged equations for low collisionality neoclassical fluxes in large aspect ratio stellarators with mirror ratios close to unity are derived. The equations retain finite orbit width effects by employing the second adiabatic invariant $J$ as a velocity-space coordinate and they have been implemented in the orbit-averaged neoclassical code KNOSOS (Velasco et al., J. Comput. Phys., vol. 418, 2020, 109512; Velasco et al., Nucl. Fusion, vol. 61, 2021, 116013). The equations are used to study the $1/\nu$ regime and the lower collisionality regimes. For generic large aspect ratio stellarators with mirror ratios close to unity, as the collision frequency decreases, the $1/\nu$ regime transitions directly into the $\nu$ regime, without passing through a $\sqrt {\nu }$ regime. An explicit formula for the neoclassical fluxes in the $\nu$ regime is obtained. The formula includes the effect of particles that transition between different types of wells. While these transitions produce stochastic scattering independent of the value of the collision frequency in velocity space, the diffusion in real space remains proportional to the collision frequency. The $\sqrt {\nu }$ regime is only recovered in large aspect ratio stellarators close to omnigeneity: large aspect ratio stellarators with large mirror ratios and optimized large aspect ratio stellarators with mirror ratios close to unity. Neoclassical transport in large aspect ratio stellarators with large mirror ratios can be calculated with the orbit-averaged equations derived by Calvo et al. (Plasma Phys. Control. Fusion, vol. 59, 2017, 055014). In these stellarators, the $\sqrt {\nu }$ regime exists in the collisionality interval $(a/R) \ln (R/a) \ll \nu _{ii} R a/\rho _i v_{ti} \ll R/a$ . In optimized large aspect ratio stellarators with mirror ratios close to unity, the $\sqrt {\nu }$ regime occurs in an interval of collisionality that depends on the deviation from omnigeneity $\delta$ : $\delta ^{2} |\ln \delta | \ll \nu _{ii} R a/\rho _i v_{ti} \ll 1$ . Here, $\nu _{ii}$ is the ion–ion collision frequency, $\rho _i$ and $v_{ti}$ are the ion gyroradius and thermal speed, and $a$ and $R$ are the minor and major radii.

Effect of anisotropic fast ions on internal kink stability in DIII-D negative and positive triangularity plasmas

Recent DIII-D experiments show that sawtooth stability is strongly affected by anisotropic fast ions from neutral beam injection (NBI) in both negative and positive triangularity plasmas. Fast ions from co-current NBI are stabilizing for the sawtooth stability, resulting in longer sawtooth periods. On the other hand, fast ions from counter-current NBI are destabilizing, leading to small and frequent sawteeth. The relative change of sawtooth period and amplitude is more than a factor of two. These observations appear to hold in both plasma shapes. Non-perturbative toroidal modeling, utilizing the magnetohydrodynamic-kinetic hybrid stability code MARS-K (Liu et al 2008 Phys. Plasmas 15 112503), reveals an asymmetric dependence of the stability of the n = 1 (n is the toroidal mode number) internal kink mode on the injection direction of NBI, being qualitatively consistent with the experimentally observed sawtooth behavior. The MARS-K modeling results suggest that anisotropic fast ions affect the mode growth rate and frequency through both adiabatic and non-adiabatic contributions. The asymmetry of the internal kink mode instability relative to the NBI direction is mainly due to the non-adiabatic contribution of passing fast ions, which stabilize (destabilize) the internal kink with the co-(counter-) current NBI as compared to the fluid counterpart. However, finite orbit width (FOW) correction to passing particles partially cancels the asymmetry. Trapped particles are always stabilizing due to precessional drift resonance. Modeling also shows that fast ions affect the internal kink in a similar manner in both negative and positive triangularity plasmas, although being slightly more unstable in the negative triangularity configuration already in the fluid limit. The similarity is mainly attributed to the fact that the mode is localized in the plasma core region, with very similar eigenmode structures in both negative and positive configurations. Furthermore, MARS-K modeling indicates that other factors, such as the plasma rotation and the drift kinetic effects of thermal plasmas, weakly modify the mode stability as compared to the drift kinetic resonance effects and FOW correction of fast ions.

Characterization of beam ion loss in high poloidal beta regime on EAST

A critical issue for achieving the integrated operation of steady-state long-pulse high-confinement (H-mode) plasmas on experimental advanced superconducting tokamak (EAST) is to improve beam ion population confinement during neutral beam injection (NBI). To study the characterization of beam ion loss and improve beam ion confinement, the steady-state long pulse scenario discharges were conducted on EAST (β p ⩾ 2.0, β N ⩾ 1.7, q 95 ⩾ 6.7 and H 98y2 ⩾ 1.1) with NBI heating. Based on neutron yield, the beam voltage and line-averaged electron density were adjusted from 50 kV to 60 kV and 4.4 × 1019 m−3 to 5.0 × 1019 m−3, respectively. The results show that the dominant mechanisms of beam ion loss are shine-through loss, prompt loss, and stochastic ripple loss. The shine-through loss fraction is determined by initial velocity, flight time and entire beam path. The change in prompt loss fraction is caused by the change in the deposition of beam ions. The change in stochastic ripple loss fraction is caused by the change in the initial fraction of trapped-confined ions. Detailed physics shows that the prompt loss fraction during counter-Ip injections (∼45%) is far larger than during co-Ip injections (∼5%) due to the finite orbit width. The lost ions are mainly deposited on the lower divertor or below the midplane since the direction of magnetic drift is vertical down. The orbit types of prompt loss during counter-Ip injections are mainly trapped-lost and ctr-passing lost. To minimize the prompt loss fraction during counter-Ip injections, a reversed Ip configuration (rev-Ip) discharge #94758 was conducted. The result suggests that the beam ion wall load fraction during counter-Ip tangential injection (∼3%) is far lower than that in normal Ip configuration (nor-Ip) discharge #94820. It is also found that the confinement of beam ion population in the counter-Ip injection #94758 was greatly improved when compared to #94820. This study can provide unique support for the improvement of beam ion population confinement and for the performance evaluation of the NBI system on EAST and future tokamaks.

Influence of adiabatic response of passing energetic ions on high-frequency fishbone

Adiabatic response effects on high-frequency fishbone instability driven by passing energetic ions are studied. With finite orbit width effects, the adiabatic contribution is derived analytically for purely passing energetic ions. By approximating the adiabatic contribution to the first order of the reverse aspect ratio we derive one of its analytic expressions, which is expected to be more accurate than that in a previous work (Graves J P 2004 Phys. Rev. Lett. 92 185003). For high-frequency fishbone instability, nonadiabatic response is usually dominant over adiabatic response, but under certain circumstances the latter plays an important role, comparable to the former. With a more generalized distribution function by introducing Gaussian-type factors representing their pitch and radial dependences and using a slowing-down equilibrium distribution for the energy of energetic ions, numerical analysis indicates that the adiabatic contribution is conducive to stabilization of the mode and causes a decrease in mode frequency. In addition, we find that the adiabatic contribution has a weak stabilizing effect on the fishbone instability when the finite orbit width effect is taken into account. We further analyze the dependence of the adiabatic contribution on the characteristic parameters of the distribution function. When the neutral beam has either a larger deviation from the plasma axis or a larger radial profile, the adiabatic contribution has a more evident effect on the fishbone instability. When the neutral beam has a relatively small critical energy, the adiabatic contribution has a greater effect on the mode instability.

A Novel Mathematical Method to Diagnose the Transverse Growth Deficit of the Nasomaxillary Complex.

The diagnosis of transverse growth deficit of the maxilla in daily clinical practice is carried out mainly through the experience of a well-trained clinician, which implies a lack of objective criteria applicable in a protocolized manner. The objective of this study was to establish a mathematical method to diagnose maxillary compression in relation to the dimensions of the skull and mandible. Methods: Records of 97 cases with an overall mean age of 9.8 ± 2.6 years were analyzed by three experienced orthodontists. The group of transverse compression was comprised of 62 cases and the control group of 35 cases. The main measurements of the widths were made on a frontal teleradiography of the skull (cranial, zygomatic, orbital, maxillary, bigonial and biantegonial width) and a lateral teleradiography of the skull (facial axis, mandibular plane, SNA, SNB, ANB and Wits). It was established that from the cranial width it is possible to predict the group to which each subject studied belongs—the compression group or the control group. A mathematical formula was obtained in the form of logistic regression that allows for the diagnosis of the presence of maxillary compression based on the cranial, maxillary and orbital widths with a sensitivity of 88.7% and a specificity of 77.1%.

Orbital Aging: A Computed Tomography-Based Study of 240 Orbits.

Previous studies have attempted to explain age-related changes to the orbit in isolation, often producing conflicting results. The authors used highly accurate imaging software to analyze computed tomographic scans to characterize changes related to age objectively. In this case-control study, patients seen in an ear, nose, and throat clinic were screened for study entry. Male and female participants were divided into two age groups (20 to 30 years and 60 to 75 years). Primary outcomes included measurement of bony orbital dimensions, volume of soft tissues (muscle and fat volume), and anterior globe position. Three-dimensional reconstructions were created of each orbit allowing these measurements. The generalized estimating equation was used so that both orbits from each patient could be included without any bias. The final sample included 240 orbits from 120 patients. There were 30 patients in each age group. Among female participants, the bony orbital volume ( p < 0.05), fat volume ( p < 0.01), and central width ( p < 0.001) of the bony orbit increased with age. The anterior globe position was significantly greater in older female participants ( p < 0.01). For male participants, the fat volume ( p < 0.0001) and central height ( p < 0.03) increased with age; the lateral rim moved posteriorly with age ( p < 0.007). The anterior globe position was not different between the age groups in male participants ( p = 0.56). The female bony orbit expands with age and is associated with a more anterior position of the globe; the male bony orbital volume remains the same and the lateral rim moves posteriorly.