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Welcome to the SPARC wiki!
This wiki will document the entirety of the Student Particle Accelerator Reproduction Chamber (SPARC) project. Everything from a tutorial for new contributors looking to make their first additions to the software to explanations of the underlying physics utilized in this project can be found here!
This project is aimed at creating a multidisciplinary experience in constructing an apparatus that demonstrates some concept of undergraduate-level physics using accelerated electrons. Using configurable extensions, the SPARC apparatus is intended to replicate several classic experiments in physic such as the double slit diffraction of electrons and the Stern-Gerlach experiment demonstrating the quantized nature of electron magnetic moments. It will also be used to reproduce other effects introduced in elementary physics, such as relativistic effects on high-velocity particles. The software app is a simulation of the electron beam's trajectory given the configuration of the SPARC apparatus.
The first phase of the project will consist of assembling a cathode ray tube that contains a cathode and anode connected to an external voltage source. This will give the contributors experience in assembling a working implosion proof apparatus.
The second phase of the project will be focused on adding the hardware with an electron gun that is created from scratch. This phase of the project will be focused on creating the basic configuration SPARC apparatus and familiarizing the contributors with a more elegant design approach that directly calls upon their understanding of the physics involved. There may be updates to the app as well during this phase, but no new features are expected to be added.
The third phase of the project will add extensions to the basic configuration, allowing experiments like the double slit diffraction of electrons to be replicated. Changes will be made to both the hardware as well as the app to adequately simulate the electron beam and the transformations being done by the modules added in the extensions. Eventually, the whole apparatus may be under vacuum.
In the basic configuration, SPARC consists of a single vacuum tube, containing a tungsten filament and a copper coil anode, a phosphor screen, and a metallic back plate cathode. Electrons are emitted via thermionic emissions, and those that make it to the other side of the copper coil are accelerated by an electric field between the anode and cathode. The beam of electrons hit the phosphor screen which will light up where the electron beam impacts the screen.
In this configuration, a metal plate (opaque to electrons) with two slits cut vertically will be placed in front of the electron gun assembly. The electrons will undergo diffraction when they pass through the double slits, and the interference pattern should be noticeable as several bands of varying intensity spaced horizontally on the phosphor screen. The SPARC app will render several a mesh of the plate and several curved planes corresponding with the paths electrons will take to reach the center of the first few bright fringes on the phosphor plate.
In this configuration, a pair of parallel neodymium magnets are placed in front of the electron gun with the magnets oriented horizontally. This will create a vertically aligned, near uniform magnetic field which by the Lorentz force will deflect the electrons to the left or right, depending on the orientation of the magnetic field. Using higher voltages, it should be possible to accelerate electrons to at least 0.5c which would allow relativistic effects to be noticeable. Using this configuration, the SPARC app will render meshes of the magnets and both the classically derived and relativistically derived trajectories, allowing the user to see the difference caused by the incredibly high speeds involved and the increased accuracy of relativistic models.
In this configuration, in addition to the parallel neodymium magnets from the Lorentz Force Demonstration, a parallel capacitor set will be placed so that the capacitors are oriented vertically. They will generate an electric field that will cancel out the effects of the Lorentz force, leaving just the magnetic moment interactions. This will result in the electrons diverging vertically based upon whether or not they are spin-up or spin-down after passing through the magnetic field, producing two bright fringes on the phosphor screen. The SPARC app will render an additional mesh for the parallel capacitor and generate two curves corresponding to the trajectory of the electrons of either spin after passing through the magnetic field.