KSU image.pngBonnies images.pngIon Beam Buncher

by Mary Harner

supervisor:  Dr. Itzik Ben-Itzhak

Kansas State University Physics  REU Program


Project Overview:

 

Bunching an ion beam in time is not a novel idea, the novel aspect of the project I worked on this summer is the method used.This project focuses on building an ion buncher that performs at equal to or higher efficiency than a typical buncher by apply a single voltage change quickly to a segment of an ion beam.This buncher will be used primarily for two experiments.For a collisions experiment this will provide a useful initial time measurement.This allows for more accurate time of flight measurements.For laser experiments a bunch is useful for increased density.With these goals in mind the buncher was designed with shortest possible pulse lengths and highest possible density.

 

Research Description:

During my REU I worked on simulations that tested different possible geometries for this buncher searching for the design that would best fit the aforementioned requirements.I was then faced with the practical difficulties of actually designing the device to be built.This was an excellent use of my first research experience because it provided a comprehensive bridge from theoretical concepts to physical results.

Process:

I worked primarily with the programs Simion, Origin, and Mathmatica to build simulations to test buncher designs.

Week One: Math Basics

For the first week I familiarized myself with the project and worked through the basic math that the project was based on (see slide three of the Final Presentation).

Week Two: Program Orientation

For the second week I spent a majority of my time creating programs in mathmatica from the equations found in week one.These programs were used to find possible geometries for the buncher.I also familiarized myself with Origin and Simion.

Week Three: Simulations Begin

For the third week I built my first geometry files for Simion and began running simulations on ion.I used origin to graph the results of the simulation and began looking for the best method to interpret the information.

Week Four: Choosing a Working Geometry

Of the previously created geometry files I chose one to focus my tests on and began testing the geometry more vigorously to determine if the buncher concept would work.

Week Five: Tails

For the Fifth week I focused my attention of the tails, the ions that were not being forced into the bunch.I determined what was causing the tails.It was decided a chopper could be used to eliminate them.

Week Six: Magnification

For the sixth week I looked into the magnification in the y direction.I began looking for a solution to this problem.

Week Seven: Voltage Dependence

For the seventh week I investigated the affects changing the voltage had on the Time of Flight, density, and magnification.I had hoped I might be able to reduce the magnification by changing the voltage but this wasnít the case.I also discovered that when the voltage was raised to high the time pulse split into two peaks.

Week Eight: New Geometry

For the eighth week I began running tests on a geometry with design practicality in mind.I lengthened a portion of the buncher to increase density and lengthened the inner diameter to better accommodate the beam and allow easier tuning.

Week Nine: Design

For the ninth week I designed the physical buncher.Based on part availability and physical constraints of the system I altered the geometry from week eight slightly and ran a few quick simulatiosn.

Week Ten: Parts

For the tenth week I ordered the parts that I could not find in the lab and left a drawing of how I believed the device should be assembled.

 

Final Presentation:

 

PowerPoint PDF (incomplete)

Power Point Outline (incomplete)

 

About Me:

Iím a final semester Physics student at St. Bonaventure University.

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