Pedestal Structure without and with 3D Fields

2014 ◽  
Vol 54 (4-6) ◽  
pp. 484-492 ◽  
Author(s):  
J. D. Callen
Keyword(s):  
3D Fields

Neoclassical toroidal viscosity torque prediction via deep learning

2021 ◽  
Author(s):  
Mitchell D Clement ◽  
Nikolas Logan ◽  
Mark D Boyer
Keyword(s):  
High Performance ◽  
Plasma Stability ◽  
Energy Distributions ◽  
Coil Current ◽  
Neutral Beams ◽  
Edge Localized Modes ◽  
3D Fields ◽  
Neoclassical Toroidal Viscosity ◽  
Data Representative ◽  
Plasma Profile

Abstract GPECnet is a densely connected neural network that has been trained on GPEC data, to predict the plasma stability, neoclassical toroidal viscosity (NTV) torque, and optimized 3D coil current distributions for desired NTV torque profiles. Using NTV torque, driven by non-axisymmetric field perturbations in a tokamak, can be vital in optimizing pedestal performance by controlling the rotation profile in both the core, to ensure tearing stability, and the edge, to avoid edge localized modes (ELMs). The Generalized Perturbed Equilibrium Code (GPEC) software package can be used to calculate the plasma stability to 3D perturbations and the NTV torque profile generated by applied 3D magnetic fields. These calculations, however, involve complex integrations over space and energy distributions, which takes time to compute. Initially, GPECnet has been trained solely on data representative of the quiescent H-mode (QH) scenario, in which neutral beams are often balanced and toroidal rotation is low across the plasma profile. This work provides the foundation for active control of the rotation shear using a combination of beams and 3D fields for robust and high performance QH mode operation.

scholarly journals Magnetic polarization measurements of the multi-modal plasma response to 3D fields in the EAST tokamak

2018 ◽  
Vol 58 (7) ◽  
pp. 076016 ◽  
Author(s):  
N.C. Logan ◽  
L. Cui ◽  
H. Wang ◽  
Y. Sun ◽  
S. Gu ◽  
...  
Keyword(s):  
Magnetic Polarization ◽  
Polarization Measurements ◽  
Plasma Response ◽  
3D Fields

HIGH-ORDER OUT-OF-PLANE EXPANSION FOR 3D FIELDS

2011 ◽  
Vol 26 (10n11) ◽  
pp. 1807-1821 ◽  
Author(s):  
K. MAKINO ◽  
M. BERZ ◽  
C. JOHNSTONE
Keyword(s):  
Fixed Point Problem ◽  
Precise Determination ◽  
Point Problem ◽  
Detailed Knowledge ◽  
Machine Precision ◽  
Out Of Plane ◽  
3D Fields ◽  
Finite Element Schemes ◽  
Careful Assessment

The precise determination of the dynamics in accelerators with complicated field arrangements such as Fixed Field Alternating Gradient accelerators (FFAG) depends critically on the ability to describe the appearing magnetic fields in full 3D. However, frequently measurements or models of FFAG fields postulate their behavior in the midplane only, and rely on the fact that this midplane field and its derivatives determine the field in all of space. The detailed knowledge of the resulting out-of-plane fields is critical for a careful assessment of the vertical dynamics. We describe a method based on the differential algebraic (DA) approach to obtain the resulting out-of-plane expansions to any order in an order-independent, straightforward fashion. In particular, the resulting fields satisfy Maxwell's equations to the order of the expansion up to machine precision errors, and without any inaccuracies that can arise from conventional divided difference or finite element schemes for the computation of out-of-plane fields. The method relies on re-writing the underlying PDE as a fixed point problem involving DA operations, and in particular the differential algebraic integration operator. We illustrate the performance of the method for a variety of practical examples, and obtain estimates for the orders necessary to describe the fields to a prescribed accuracy.

scholarly journals X-type vortex and its effect on beam shaping

2021 ◽  
Author(s):  
Xiaoyan Pang ◽  
Weiwei Xiao ◽  
Han Zhang ◽  
Chen Feng ◽  
Xinying Zhao
Keyword(s):  
Three Dimensional ◽  
Beam Shaping ◽  
Optical Fields ◽  
Intensity Pattern ◽  
Phase Gradient ◽  
Rotation Direction ◽  
3D Space ◽  
New Type ◽  
Gradient Parameter ◽  
3D Fields

Abstract In this article we propose a new type of optical vortex, the X-type vortex. This vortex inherits and develops the conventional noncanonical vortex, i.e., it no longer has a constant phase gradient around the center, while the intensity keeps invariant azimuthally. The strongly focusing properties of the Xtype vortex and its effect on the beam shaping in three-dimensional (3D) fields are analyzed. The interesting phenomena, which cannot be seen in canonical vortices, are observed, for instance the `switch effect' which shows that the intensity pattern can switch from one transverse axis to another in the focal plane by controlling the phase gradient parameter. It is shown that by adjusting the phase gradient of this vortex, the focal field can have marvelous patterns, from the doughnut shape to the shapes with different lobes, and the beam along propagation direction will form a twisting shape in 3D space with controllable rotation direction and location. The physical mechanisms underlying the rule of the beam shaping are also discussed, which generally say that the phase gradient of the X-type vortex, the orbital angular momentum, the polarization and the `nongeneric' characteristic contribute differently in shaping fields. This new type of vortex may supply a new freedom for tailoring 3D optical fields, and our work will pave a way for exploration of new vortices and their applications.

scholarly journals The “Triple Point” on 24 May 2002 during IHOP. Part II: Ground-Radar and In Situ Boundary Layer Analysis of Cumulus Development and Convection Initiation

2007 ◽  
Vol 135 (7) ◽  
pp. 2443-2472 ◽  
Author(s):  
Conrad L. Ziegler ◽  
Erik N. Rasmussen ◽  
Michael S. Buban ◽  
Yvette P. Richardson ◽  
L. Jay Miller ◽  
...  
Keyword(s):  
Boundary Layer ◽  
Triple Point ◽  
Potential Temperature ◽  
Wind Fields ◽  
Analysis Technique ◽  
3D Fields ◽  
Water Vapor Mixing Ratio ◽  
Convection Initiation ◽  
Water Saturated

Abstract Cumulus formation and convection initiation are examined near a cold front–dryline “triple point” intersection on 24 May 2002 during the International H2O Project (IHOP). A new Lagrangian objective analysis technique assimilates in situ measurements using time-dependent Doppler-derived 3D wind fields, providing output 3D fields of water vapor mixing ratio, virtual potential temperature, and lifted condensation level (LCL) and water-saturated (i.e., cloud) volumes on a subdomain of the radar analysis grid. The radar and Lagrangian analyses reveal the presence of along-wind (i.e., longitudinal) and cross-wind (i.e., transverse) roll circulations in the boundary layer (BL). A remarkable finding of the evolving radar analyses is the apparent persistence of both transverse rolls and individual updraft, vertical vorticity, and reflectivity cores for periods of up to 30 min or more while moving approximately with the local BL wind. Satellite cloud images and single-camera ground photogrammetry imply that clouds tend to develop either over or on the downwind edge of BL updrafts, with a tendency for clouds to elongate and dissipate in the downwind direction relative to cloud layer winds due to weakening updrafts and mixing with drier overlying air. The Lagrangian and radar wind analyses support a parcel continuity principle for cumulus formation, which requires that rising moist air parcels achieve their LCL before moving laterally out of the updraft. Cumuli form within penetrative updrafts in the elevated residual layer (ERL) overlying the moist BL east of the triple point, but remain capped by a convection inhibition (CIN)-bearing layer above the ERL. Dropsonde data suggest the existence of a convergence line about 80 km east of the triple point where deep lifting of BL moisture and locally reduced CIN together support convection initiation.

Visual Analysis of Multi-Parameter Distributions across Ensembles of 3D Fields

2021 ◽  
pp. 1-1
Author(s):  
Alexander Kumpf ◽  
Josef Stumpfegger ◽  
Patrick Fabian Hartl ◽  
Ruediger Westermann
Keyword(s):  
Visual Analysis ◽  
3D Fields ◽  
Parameter Distributions

scholarly journals SPH Modelling of Hydrodynamic Lubrication along Rough Surfaces

Lubricants ◽  
2019 ◽  
Vol 7 (12) ◽  
pp. 103
Author(s):  
Marco Paggi ◽  
Andrea Amicarelli ◽  
Pietro Lenarda
Keyword(s):  
Hydrodynamic Lubrication ◽  
Load Capacity ◽  
Surface Texturing ◽  
Textured Surfaces ◽  
Slider Bearing ◽  
Plate Interface ◽  
Particle Hydrodynamics ◽  
Artificial Surface ◽  
Smoothed Particle ◽  
3D Fields

Rough and textured surfaces are of paramount importance for lubrication, both in nature and in technology. While surface roughness relevantly influences both friction and wear, artificial surface texturing improves the performance of slider bearings as an energy efficiency action. The simulation of hydrodynamic lubrication by taking into account complex surfaces as boundaries requires the use of computational fluid dynamics (CFD) software able to predict the pressure and the velocity profile through the thickness of the fluid and at any point within the 3D domain. In the present study, a CFD–smoothed particle hydrodynamics (SPH) code is applied to simulate hydrodynamic lubrication for a linear slider bearing in the presence of a 3D rough surface, showing the capabilities of CFD–SPH in modelling such complex interaction phenomena. Numerical assessments involve the load capacity, the 3D fields of the velocity vector, and the pressure 3D field (both within the fluid domain and at the fluid–plate interface).

Application of Satellite- and NWP-Derived Wind Profiles to Military Airdrop Operations

2016 ◽  
Vol 55 (10) ◽  
pp. 2197-2209 ◽  
Author(s):  
David C. Meier ◽  
Steven T. Fiorino
Keyword(s):  
Wind Profile ◽  
Weather Prediction ◽  
Wind Data ◽  
Atmospheric Infrared Sounder ◽  
Equipment And Supplies ◽  
Energy Applications ◽  
Directed Energy ◽  
Wind Profiles ◽  
3D Fields ◽  
Profile Accuracy

AbstractThe Joint Precision Airdrop System (JPADS) has revolutionized military high-altitude airdrop capability, allowing delivery of equipment and supplies to smaller drop zones from higher altitudes than was previously possible. This capability relies on accurate wind data, currently provided by GPS dropsondes released in the vicinity of the drop zone shortly before the airdrop. This research investigates the potential for a wind-profiling algorithm to generate the required wind data from passive IR and microwave satellite soundings, eliminating the requirement for a hazardous dropsonde pass near the drop zone. The Atmospheric Infrared Sounder (AIRS) provides a 3D temperature field and determines the heights of 100 standard levels. From these data, the slopes of the isobaric pressure surfaces and temperature gradients are used to calculate wind speed and direction using the thermal wind relationship. The accuracy of these satellite-derived wind profiles is evaluated through comparison with rawinsonde measurements near the coordinates and time of the AIRS sounding. Further investigation of the wind profile accuracy is made by a comparison with numerical weather prediction (NWP) data worldwide, and the effect of cloud cover in the vicinity of the target coordinates is analyzed. The AIRS-derived winds are found to be less accurate than short-term NWP winds for the JPADS application, but the technique developed may be applied to alternate applications, such as use in the stratosphere, where NWP winds are not widely available. The agreement between satellite-retrieved temperatures and measurements at altitudes above 30 km indicates the AIRS data could be used to create accurate, 3D fields of optical turbulence strengths for directed-energy applications.

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