Fusion Physics - Energy Boon or Nuclear Gloom? David Schilter and Shivani Sharma
Problem Statements... • Is it possible to construct a potential array (electrostatic potential well) which would allow for resulting energy close to or exceeding applied voltage? • What electrode configuration in an IEC device can both avoid energy loss due to space charge as well as encouraging ion acceleration? • Would the idea of circulating ions provide a solution to the problems of space charge while also inducing nuclear fusion?
Plasmas • AC grid causes radio frequency discharge which creates oscillating B and E ionizes the hydrogen gas used to create a plasma, a mixture of high energy ions and electrons • Diffuses into a chamber that also contains a neutral hydrogen background gas, which is not affected by the electrodes
Experimental Setup • Inner spectacle (=22mm) cathode • Outer mesh anode (earthed) • Pressure maintained at 5mTorr (7x10-6 atm) • Magnetic field was set at 70 gauss (7x10-3 T) • Voltages of 1-10kV applied to cathode
B Inner rings (cathode, -ve bias) Outer mesh (anode) Electrode Geometry
Some theory... • The H line (656.3nm) represents the first atomic transition in the Balmer series (from n=3 to n=2) • 1/ = RH[(1/2)2 - (1/n)2] where Rydberg’s constant = RH = 1.0968x107m-1 • The spectrometer measures intensity near this wavelength, providing a wavelength distribution. • Fusion cross-section (probability) of 1H is many orders of magnitude less than deuterium (2H) or tritium (3H)
Charge exchange reactions occur as fast,ionized plasmacollideswith stationarybackground gas In all cases, the high energy plasma becomes unstable due to the exchange and fragments This results in the excited radical H* which is detected by the spectrometer H++ HH*+ H+ H2++ H H*+ H+ H+ H3++ H H*+ H2+ H+ H++ H2 H*+ H2+ H2++ H2 H*+ H + H2+ H3++ H2 H*+ H2+ H2+ analysed Charge-exchange Reactions
Observations • Very slight circulation of ions observed between two rings, which were red hot • Majority of ions passed through, and continued in a roughly linear path, which created “beams” • Purple colour characteristic of high energy hydrogen
H-line “knee” Energy Distributions • Shifts involved are characteristic of the various charge-exchange reactions • The “knee” relates to the most energetic ions • Intense alpha line is due to background gas • Note symmetryions moving toward and away from spectrometer
Results Continued... • Energy plotted against voltage results in a linear relationship • It was also found that that B had no effect on the maximum ion energies • Efficiency=gradient, which in this case is approximately 7%
Conclusions • Excited and Doppler shifted atoms were observed at wavelength up to 0.89nm greater than that of the H line (o=656.3nm) corresponding to energies of 8.7x10-1keV • Efficiency of 7% clearly too lownew grid design • B not strong enough to induce circulation in a large proportion of the ions • Ions accelerated from each direction rather than in a circular motion to avoid the “virtual anode” • The simulation of the exact same conditions were undertaken and discrepancies accounted for...