The Construction of a Small Dense Plasma Focus
Using a Novel Experimental Setup
For a couple of years, Adam Bowman, a 2012 graduate of Montgomery Bell Academy, has been conducting independent research into small dense plasma focus (DPF) devices as effective radiation sources and research tools. The DPF utilizes a fast, high-energy discharge from a capacitor bank to create a very hot, dense column of plasma at the end of two coaxial electrodes in a low pressure environment, and will serve as a powerful source for X-rays, UV light, and neutrons.
Most of the research conducted with DPF’s thus far has utilized multi-kilojoule devices, which are both expensive and large. Bowman’s goal is to develop a small, low-voltage device that would incorporate an SCR-based (thyristor) switching circuit to increase radiation yields. As a portable neutron and X-ray source, this DPF-based system would not only be cost-effective, but also simplify existing non-radioisotope sources, which require both high vacuum environments and high voltage accelerating potentials.
In order for Bowman to begin conducting diagnostics and research with this device, he needed to have a digital storage oscilloscope and implemented B&K Precision’s donated Model 2540 DSO into his test setup. “The use of an oscilloscope is central to my research since the plasma focus process from breakdown to pinch occurs on the order of a microsecond,” said Bowman. The 2540 was capable of resolving this non-repetitive process and enabled him to continue his research to the next phase of testing. “Using the 2540 DSO, I have been able to observe the current derivative signal from the plasma focus discharge – basically a big LRC circuit - and view the soft X-ray flux emanating from the pinch,” stated Bowman.
In addition to testing the plasma focus directly, he has also used the DSO to analyze the trigger circuit for the triggered spark gap. Other useful applications of the scope included testing the assembly of Bowman’s photomultiplier/scintillator and assisting him in the build of a regulated power supply for his capacitance manometer vacuum gauge, a device that measures pressure in the vacuum chamber for the DPF.
When asked about the functionality of the 2540 DSO, Bowman responded, "The CSV output format has probably been the most useful feature, as it allows me to process the data in Excel. In terms of data analysis, the oscilloscope's math features have turned out to be very important, especially the multiplication feature. Additionally, I have begun work with my physics teacher on trying to extract some useful information from the FFT of the current derivative and photodiode signals."
The 2540 digital storage oscilloscope and the Dense Plasma Focus, ready for testing.
Adam Bowman
Adam Bowman finished his senior year of high school in 2012 at Montgomery Bell Academy in Nashville, TN. His interest in this project derives from his interests in nuclear physics and engineering. Here is his list of some of his accomplishments:
- 1st place at the Tennessee Junior Science and Humanities Symposium in 2012
- Grand prize winner at the Middle Tennessee Science and Engineering Fair in 2012, 2011 and 2010
- 4th place in physics at the Intel International Science and Engineering Fair in 2010 for my project involving the construction of a small, electrostatic linear particle accelerator
- 1st place award from the American Vacuum Society at ISEF 2010
- 3rd place in physics at the Intel ISEF in 2011 for my plasma focus research
- Albert Langdon Swank Experimental physics award and scholarship at ISEF 2011 (plasma focus research)
- 1st place in statewide TMTA math competition in statistics (2011)
- Competitor in the national Science Olympiad tournament for two consecutive years (multiple state-level awards) through our high school's team
Montgomery Bell Academy
Montgomery Bell Academy enjoys a 144-year history as a college preparatory school for young men in grades 7-12, offering a progressive approach to traditional education. MBA provides for its students a determined balance among academics, athletics, and fine arts.
