by Mary Harner
supervisor: Dr. Itzik Ben-Itzhak
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.
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.
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.
PowerPoint PDF (incomplete)
Power Point Outline (incomplete)
Iím a final semester Physics student at St. Bonaventure University.