CTSP (Contamination Transport Simulation Program)






Overview

CTSP (Contamination Transport Simulation Program) is a PIC-C developed program for modeling molecular and particulate contamination transport. The need to model contamination is commonly encountered in vacuum and aerospace industries. Plastics and other organic materials exposed to low pressures outgas unspent hydrocarbons which then deposit onto sensitive surfaces such as camera lenses or radiators. Other components may be sensitive to particulates. These are tiny dust particles arising from air pollution, garments, or flaking off paints. Particulates are present on all surfaces but can redistribute during vibrational events such as spacecraft launch or on-orbit deployments.

CTSP models the transport of molecular and particulate contaminants from their sources to the eventual target settling locations in order to estimate the end of life cleanliness levels. The code utilizes a kinetic method in which the contaminants are represented by simulation particles. Particle positions are advanced through small time steps. This allows the code to take into account aerodynamic, gravitational, or electrostatic forces. Unlike Monte Carlo ray tracing tools, CTSP concurrently simulates the entire contaminant population. This allows the end user to visualize the contaminant plume partial pressures and bulk streaming velocities. It also allows the code to simulate the transition regime (such as chamber repress) in which inter-molecular collisions become important. CTSP supports highly detailed, multi-million element surface meshes to represent the test geometry. The code also implements multiple contamination-specific material sources, including a detailed model for molecular outgassing and particulate generation. Molecular surface adhesion and desorption physics is governed by surface temperature and material activation energy.