The fraction of incident light which is reflected from a surface element.
chamber components library
A library containing both chamber components provided with the VISRAD distribution and custom chamber components generated by individual users. The user can generate and save custom chamber components in the library for later re-use. Chamber components in the library can be grouped into folders.
chamber components list
List of chamber components located on the left side of the user interface main window.
clipping (or bounding) volume
A volume used for surface removal of a target component.
This allows the user, for example, to set up a cylinder with a hole in the
side of it. Clipping volumes operate on only one object at a time. That is,
the bounding volume used to drill a hole in the cylinder above would not
also drill a hole in any other target components, unless an identical bounding volume
was also applied to that target component.
comma-separated values (CSV) file
Ascii file consisting of a table of data with an arbitrary number of rows. The data within each row are separated by some character, which is typically a comma.
diagnostic ports
Ports, or holes, at fixed positions in the experimental target chamber
from which diagnostic instruments view the experiments. The angles to the
ports are more-or-less fixed. However, offsets of the target with respect
to target chamber center or offsets in the diagnostic instruments can change
these angles slightly.
emission temperature
Temperature associated with the flux out of a given surface element:
(σ TE4
= emitted flux).
GEKKO XII
Laser facility at the Institute for Laser Engineering at Osaka University, Japan.
generalized mesh object
An object of arbitrary shape defined only by an array of nodes and connectivity. Generalized mesh objects are distinct from VISRAD primitives, such as cylinders and spheres, in that they are not defined using a radius or a length, or a user-specified number of nodes.
glint
The specular reflection of light off a surface. In VISRAD, glint
refers to the reflection of laser light.
key points of target components
Points of target components that are common reference points (e.g., the corners of a rectangle or top of a cylinder).
laser beam system
A fixed set of laser beams (typically ~ 10 to 200) in a target chamber.
Laser beams can be grouped into "clusters" to allow the user to
adjust parameters for groups of beams. Laser beam parameters can be specified
either: individually, by cluster, or as a whole system.
laser ports
Ports at fixed positions in the experimental target chamber through
which laser beams enter the chamber.
laser reflectivity
The fraction of laser light incident on a surface that is specularly
reflected.
LMJ (Laser Megajoule)
The laser facility near Bordeaux, France.
MEC (Matter in Extreme Conditions)
The x-ray and laser facility at SLAC National Accelerator Laboratory - Stanford University.
mesh (or target grid)
A set of one or more objects that define the target.
MTW (Multi-Terawatt Laser Facility)
The single-beam multi-terawatt laser facility at the University of Rochester's Laboratory for Laser Energetics.
NIF (National Ignition Facility)
Laser facility at Lawrence Livermore National Laboratory.
OAP (Off-Axis Parabolic Mirror)
Mirror used to reflect the light from short-pulse laser beams within a target chamber. Used for the OMEGA-EP, OMEGA, and ORION target chambers.
objects (or target components)
3-D components, such as Spheres, Cylinders, or Cylindrical Hohlraums
(composed of one cylinder + two disks + two laser entrance holes (LEHs)).
Objects have surfaces of zero thickness. Surfaces have a preferred
orientation, emitting/reflecting light on one side only. (To emit/reflect
light on both sides, a second, nearly identical object must be set up which
has surface normals in the opposite direction.)
OMEGA
60-beam laser facility at the University of Rochester's Laboratory
for Laser Energetics.
OMEGA-EP
6-beam laser facility at the University of Rochester's Laboratory for Laser Energetics, consisting of 4 long-pulse beams and 2 short-pulse beams.
ORION
Laser facility being built in the United Kingdom that supports ten nanosecond-class beams in conjunction with two subpicosecond, petawatt-class beams.
Phong specular reflection model
A model used to compute the specular reflection of light off a surface.
In this model, the intensity of reflected light is proportional to [cos(φ)]η,
where φ is the angle measure relative to
the perfect reflection angle, and η is the specular reflection parameter.
In VISRAD, the Phong model is used to compute the reflection of laser light.
The specular reflection parameter, η, for each surface element is affected by the variation in the unit normal vectors at the vertices of the surface
element.
picked surface element
A surface element in the target mesh selected by the user by double-clicking
with the mouse. When picking is performed, properties for that surface element
are displayed in the Surface Element Parameters window.
PLX (Plasma Liner Experiment)
The Plasma Liner Experiment facility at Los Alamos National Laboratory.
power source term
Source term in the radiosity (power balance) equation. This includes
contributions from: laser power deposition (corrected for x-ray conversion
efficiency) and uniform self-emission.
radiation temperature
Temperature associated with the flux into a given surface element:
(σ Trad4 = incident flux).
radiosity
Radiation flux emitted from a surface element. This takes into account
contributions from power sources and reemission of incident radiation due
to all other surface elements. Once computed, the incident flux spatial distribution,
as well as the radiation and emission temperatures are readily computed.
reticle
Reticles are positioning fiducials used by the laser facility operations staff to properly orient the target within the target chamber prior to a shot.
SRF laser beam database (SRF-DB)
The database at the University of Rochester's Laboratory for Laser Energetics that contains laser beam data for shots on the OMEGA laser system. Data for the SRF-DB is entered by the principal investigators for OMEGA experiments using Shot Request Forms (SRFs).
smoothing by spectral dispersion (SSD)
A technique for smoothing (intensity) non-uniformities in a laser beam using diffraction gratings.
specular reflection
The total, or near total, reflection of light off a surface into a concentrated region about the specular reflectance angle.
STEP-formatted CAD files
STEP (Standard for the Exchange of Product data) is a commonly-used format for CAD software. Also referred to as STP-formatted files.
STL-formatted CAD files
STL (Stereolithography) is a commonly-used format for CAD software.
surface element
Objects (target components and chamber components) are subdivided into surface elements. Surface elements are
either TRIANGLES or QUADS.
tab-separated values (TSV) file
Ascii file consisting of a table of data with an arbitrary number of rows. The data within each row are separated by some a tab.
target components library
A library of target components saved by individual users. The user
can save target components from his/her current project to the library for
later re-use. Target components can be grouped into folders.
target components list
List of target components located on the left side of the user interface main window.
transmission fraction
The fraction of light that freely travels ¾ unblocked, or "unocculted" ¾ by intervening surface elements. This also takes into account self-blocking of emitting and receiving surfaces (i.e., "horizon" effects).
x-ray conversion efficiency
The fraction of laser power that is converted into x-ray power.
view factor (or configuration factor) integral
The fraction of light emitted by one surface element that reaches another surface element.
