Ion Trapping Simulation Using High-Performance Fortran

by Susan Fischer, Davidson College, Physics Major

advisors: Ken Hawick and Paul Coddington, NPAC Research Scientists

Project conducted as part of the 1994 Research Experiences for Undergraduates (REU) Program in High-Performance Computing conducted by the Northeast Parallel Architecture Center (NPAC) at Syracuse University.


Abstract

A computational physics simulation which models the behavior of ions in a ``trap'' was developed to study behavior of ions within Paul traps and Penning traps, which use electric and/or magnetic fields to confine ions. The simulation was developed, tested, and run in Fortran 90, with the intent of porting the application to High-Performance Fortran when a complete compiler is available. Parts of the code were tested on ``subset HPF.'' Development of the simulation and analysis of results required several computationally intense algorithms, including Gear and velocity-Verlet finite difference methods, and repeated calculation of long-range interaction forces and potentials. At this stage of testing, it appears that the results of the simulation agree with theory.

Introduction

What is ion trapping?

An ion trap, shown in the figure above, uses some configuration of electric and magnetic fields to confine ions to a very small (on the order of 0.001 mm) region of space. Two types of traps are modeled by this simulation: the Paul trap, which consists of a static electric potential and an oscillating electric potential, and the Penning trap, which uses a static electric potential to confine ions on the z-axis and a strong magnetic field (up to 5 Tesla, 50000 times stronger than the earth's magnetic field!!) to confine the radial position.

What are the motivations behind ion-trapping?

In a word, physics research.... confined particles are the ideal subjects of experiments involving molecular and atomic spectroscopy, quantum electrodynamics, and plasma behavior.

What do the ions do in an ion trap? What is interesting about their behavior?

Well, that depends on the experimental conditions, or, in the case of this simulation, on user-specified simulation parameters. Depending on parameters which include: the following behaviors are possible: Click here for a summary of the current stage of the project....
Click here for a detailed (.ps, 9 Mbytes) write-up of the project...
Click here for a detailed (.html, no pictures) write-up of the project...
Susan L. Fischer
Physics Department
Davidson College, North Carolina e-mail: susan@phyhost.davidson.edu