Throughout the past few decades there have been a lot of cosmological evidence that there exist some sort of matter called “Dark Matter” One of the boldest step in cosmology and the astrophysics communities is to confirm its existence and thoroughly understand it.
Now spark purification system addresses this issue, as u can see it consist of several components, for my project I focus entirely on the spark tube/box.The spark tube as a titanium electrode that runs directly through the center, when an high voltage is apply to this rod and electric field is created, if this field strength except the dielectric field strength of the gas it becomes a temporary conductor which allows electric current flow b/w both object of different potential, this electrostatic discharge is know n as a spark which basically graze small titanium dust particle of the rod. These particles then interact with the incoming noble gas, thus reducing its impurities such as O2 and CO2. This is then filtered and continues in this cycle until a suitable purification level is obtainedHere is the spark tube, and basically when a high voltage is supply to the titanium rod it generates a series of sparks that produces titanium dust particles. These particles then interact with the incoming noble gas, thus reducing its impurities such as O2 and CO2. This is then filtered and continues in this cycle until a suitable purification level is obtained.
Titanium is classified as a getter material that attacks electronegative compounds such as O2….thus allowing longer drift paths of the ionization charge.
Here is the experimental set of 0f a 1.5’’ spark tube connected to ground and a titanium electrode that runs directly through the center that is connect to a high voltage supply. The geometry of the titanium electrode was either threaded, threaded with grooves or just a simple strip with various width Throughout the experiment we realized that needed a bigger power supply, thus to avoid that issue we had to scale down the model twice to get more conclusive results.Further insight about the project and how its going to be implemented in the LUX Detector lead to the design of the spark box which only used titanium strip of various width.
Here u can see that the breakdown voltage required to generate sparks here is 6 KV, which was very high so we thought by adding grooves along the rod would reduces this but the result was not quite what we expected in fact it was 1.15 kv higher.
As the distance between the electrodes increase the breakdown voltage also increasesBut closely looking at the data with approximately the same separation distance b/w the electrodes, the strip generate sparks at a lower voltage.
Here the spark box which behaves in a similar manner to the spark tube, as the distance between the electrodes increases the voltage increases, except with the approximately the same distance b/w the electrode the spark box generate spark at 1.6 kv lower an average.
Here I am going to show u a video, where u can see as u increase the voltage over time the spark rate increases.
Throughout conducting the experiment we had a hunch that perhaps the current also affects the spark rate and the data obtain verified just that when we ran the 0.5’’ spark tube and observed the spark rate and current simultaneously.How is this necessary, well if I can control the spark rate by the voltage or current then there is a strong possibility I will be able to control the amount of titanium dust particle produce over time.
1)Also from the observations, it is explicit that the curvature of the titanium electrode is proportional to the breakdown voltage and the particle size. 2) The spark box without a doubt is superior, since sparks are generated at a lower voltage with the same separation between the electrodes as in the sparks tube. Also alignment issues of the electrodes like in the spark tube are avoided, thus making it easier for implementation in the existing model of LUX detector.
This is a type of ESD that occurs when the electric field strength exceeds the dielectric field strength, thus creating a temporary conductor which allows a quick electric current flow between to objects of different potential.
Spark Purification System <br />By <br />Kemar James<br />NSF funded REU at Case Western Reserve University<br />Advisor: Dr. Thomas Shutt, Dr. Dan Akerib<br /> and <br />Dr. Carmen Carmona<br />
Introduction:<br />Cosmological evidence of “Dark Matter”<br /> To confirm its existence and thoroughly understand it to explain the our universe and its formation.<br /> The LUX collaboration is attempting this through “direct detection” using a dual phase xenon detector.<br /> Unfortunately due to the impurity levels, the xenon needs to be purified to make longer electron drift paths possible.<br /> Thus allowing the nuclei recoil of the WIMP ( dark matter candidate) interaction to be detected.<br />
Why use a titanium electrode?<br /> It readily reacts with O2 to form titanium oxide, thus reducing the O2 impurities in xenon/argon<br /> It’s a good conductor, thus making it ideal for the electrode<br />High resistivity to corrosion<br />
LUX Detector uses xenon noble gas/liquid <br />Why xenon ?<br />Dense and homogeneous large detector masses (crucial to explore lower cross section values).<br />Inert, not flammable and very good dielectrics. <br />High electron motilities, which allows long drift distances.<br />Good scintillating abilities.<br />
Conclusions:<br />The experiment was successful in generating the sparks necessary to produce getter material (Titanium dust particles) for various electrodes geometries.<br />The curvature of the titanium electrode is proportional to the breakdown voltage .<br />The spark box without a doubt is superior, since sparks are generated at a lower voltage with the same separation between the electrodes as in the spark tube.<br />
Acknowledgements<br />This work was supported the NSF grant numbers DMR-0850037. <br />I would also like to acknowledge the program coordinators Kathleen Kash and Edith Gaffney. <br />Finally I would also like to thank my advisors Dr. Thomas Shutt , Dr. Dan Akerib, and Carmen Carmona for the tremendous work they have done to equip and guide me along this wonderful experience.<br />
References<br /> Gaitskell, R. J., Direct detection of dark matter, Ann . Rev. Nucl. Part. Sci. 54(2004) 315-359.<br /> Sorensen, P. F., “A Position-Sensitive Liquid Xenon Time-Projection Chamber for Direct detection of Dark Matter”. Ph.D. thesis (2008).<br /> Griffiths, D. J., Introduction to Electrodynamics, Third Edition. Upper Saddle River, New Jersey: Prentice Hall , 1999.<br /> Ramsey, B., Bolotnikov A., "Purification techniques and purity and density measurements of high-pressure Xe." Nucl. Inst. Meth. A 383 (1996): 619-623.<br />
What is a Spark ?<br />This is a type of ESD that occurs when the electric field strength exceeds the dielectric field strength, thus ionizing the conductive channel in the gas.<br /> This may cause a rapid increase in the number of free electrons and ions in the gas, temporarily causing the air to abruptly become an electrical conductor<br />At this point a sudden and momentary electric currentflows between two objects at different electrical potentials caused by direct contact or induced by an electrostatic field<br />
Breakdown voltage in different gaseous enviroments<br />R8778 PMT base (d=5mm)<br />
Objectives <br />Spark Purification System<br />Spark Tube<br />Identify tube and titanium electrode geometry suitable and assemble them. <br />Generate continuous sparks within a localized argon gas environment and then observe how the geometry of the titanium electrode, tube size, current and voltage affects the spark rate.<br /> Identify the dust particles generated from the sparks <br /> Make a correlation between the duration of the sparks to the mass of particles produce and the amount required to purify “x” amount of argon to a purification level of “y”. <br /> Filtration system<br />
Why the use of heavy noble gases/liquids? <br />These liquids are dense and homogeneous. This allows to construct large detector masses. This is crucial to explore lower cross section values.<br />Noble gases are inert, not flammable and very good dielectrics. <br />Liquefied noble gases do not attach electrons, and electron mobilities are high for the heavier noble gases, which allows long drift distances.<br />They are bright scintillators.<br />