[ Identification | Description | Input parameters | Links ]

# The `V_selector` Component

Velocity selector.

## Identification

- Site:
- Author: Kim Lefmann
- Origin: Risoe
- Date: Nov 25, 1998

## Description

    Velocity selector consisting of rotating Soller-like blades
    defining a helically twisted passage.
    Geometry defined by two identical, centered apertures at 12 o'clock
    position, Origo is at the centre of the selector (input is at -zdepth/2).
    Transmission is analytical assuming a continuous source.

    Example: V_selector(xwidth=0.03, yheight=0.05, zdepth=0.30, radius=0.12, alpha=48.298, length=0.25, d=0.0004, nu=20000, nslit=72)
    These are values for the D11@ILL Dornier 'Dolores' Velocity Selector (NVS 023)

    %VALIDATION
    Jun 2005: extensive external test, no problems found
    Validated by: K. Lieutenant

## Input parameters

Parameters in boldface are required; the others are optional.

Name | Unit | Description | Default |
xwidth | m | Width of entry aperture | 0.03 |
yheight | m | Height of entry aperture | 0.05 |
zdepth | m | Distance between apertures, for housing containing the rotor | 0.30 |
radius | m | Height from aperture centre to rotation axis | 0.12 |
alpha | deg | Twist angle along the cylinder | 48.298 |
length | m | Length of cylinder/rotor (less than zdepth) | 0.25 |
d | m | Thickness of blades | 0.0004 |
nu | Hz | Cylinder rotation speed, counter-clockwise, which is ideally 3956*alpha*DEG2RAD/2/PI/lambda/length | 300 |
nslit | 1 | Number of Soller blades | 72 |

AT ( | , | , |  | ) RELATIVE |  |
ROTATED ( | , | , |  | ) RELATIVE |

## Links

- Source code for `V_selector.comp`.

[ Identification | Description | Input parameters | Links ]