The effects of non-ideal electric fields and externally applied magnetic fields on the performance of parallel plate electrostatic energy analyzers
This dissertation is a theoretical and experimental investigation of how externally applied magnetic fields and intrinsic non-ideal electric fields affect the performance of parallel plate electrostatic energy analyzers. These instruments are used in heavy ion beam probe (HIBP) diagnostics to measure the space potential of magnetized, high-temperature plasmas. Several HIBP diagnostics have been operated to fusion experiments (Tara, ATF, Heloitron-E), where the magnetic field inside the analyzer is greater than 100 G. These externally applied magnetic fields, and changes in the internal analyzer electric field caused by wire meshes used inside the analyzer, alter the analyzer performance (gain curve) from what is predicted by the ideal analyzer model. A non-ideal model of the analyzer was developed which takes into account the influence of the wire meshes by dividing the analyzer into regions, each with its own electric field. These electric field strengths are determined by three parameters in the model, the electric field multipliers. The non-ideal model also allows for the presence of a homogeneous magnetic field of arbitrary orientation. The non-ideal model was used to analytically determine particle trajectories through the analyzer. Gain curves for non-ideal analyzers were calculated using these trajectories. The non-ideal analyzer gain curves have values less than those predicted by the ideal model and depend on the particle mass, injection energy, and charge state if there is a magnetic field in the analyzer. A laboratory test stand was assembled to verify the predictions of the non-ideal model. The test stand consisted of an ion gun, beamline, energy analyzer, and a set of Helmholtz coils for producing a uniform field inside the analyzer. Experimental gain curves obtained with a magnetic field verified the dependence on particle mass, injection energy, and charge state predicted by the non-ideal model.
- Research Organization:
- Texas Univ., Austin, TX (United States)
- OSTI ID:
- 7261116
- Resource Relation:
- Other Information: Thesis (Ph.D.)
- Country of Publication:
- United States
- Language:
- English
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