Measurement of MTF Target Plasma Temperature Using Filtered Photodiodes
LOS ALAMOS NATIONAL LAB NM
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Magnetized Target Fusion MTF is an approach to fusion where a preheated and magnetized plasma is adiabatically compressed to fusion conditions. Successful MTF requires a suitable initial target plasma with a magnetic field of al least 5 T in a closed-field-line topology, a density of roughly 10 to the 18th power cm-3, a temperature of at least 50 eV but preferably closer to 300 eV, and must be free of impurities which would raise radiation losses. The goal of these experiments is to demonstrate plasma conditions meeting the requirements for an MTF initial target plasma. The plasma is produced by driving a z-directed current of 1-2 MA through either a static gas-fill or a 38 micrometer diameter polyethylene fiber. The data obtained from an array of filtered photodiodes is used to estimate the plasma temperature. The filter material and thickness for each diode is chosen such that the lowest absorption edge for each is at a successively higher energy, covering the range from a few eV to 5 keV. The analysis assumes a fully stripped optically thin plasma which radiates as either a blackbody, a bremsstrahlung emitter, or a group of emission lines gaussian-like.
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