by Mary
Harner
supervisor: Dr.
Itzik Ben-Itzhak
Kansas State University Physics
REU Program
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.
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 wasn’t 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)
I’m a final semester Physics student at
St. Bonaventure University.
