[ 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		Generate
ROTATED (	,	,		) RELATIVE

Links

• Source code for V_selector.comp.

---

[ Identification | Description | Input parameters | Links ]

Generated on 2025-05-08 13:31:31

---

Last Modified: Monday, 30-Jun-2025 11:05:10 CEST