Transcript Fusion Physics - Energy Boon or Nuclear Gloom?

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
Electrode Geometry
B
Inner rings
(cathode, -ve bias)
Outer mesh
(anode)
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
• Charge exchange
reactions occur as fast,
ionized plasma collides
with stationary
background 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+ + HH* + H+
H2+ + H  H* + H+ H+
H 3+ + H  H * + H 2+ H +
H + + H 2 H * + H 2+
H 2+ + H 2  H * + H + H 2+
H 3+ + H 2  H * + H 2+ H 2+
analysed
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
• Shifts involved are
characteristic of the
various chargeexchange reactions
• The “knee” relates to
the most energetic ions
• Intense alpha line is
due to background gas
• Note symmetryions
moving toward and
away from spectrometer
Intensity vs Doppler Shift
60000
H-line
50000
40000
“knee”
30000
20000
10000
0
-3
-2
-1
0
1
doppler shift (nm)
2
3
Intensity (arb. units)
Energy Distributions
Results Continued...
Ion Energy vs Applied Voltage
E = 0.0749V + 0.1044
1.00E+00
8.00E-01
Energy (eV)
• 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%
6.00E-01
4.00E-01
2.00E-01
0.00E+00
0
5
10
Voltage (kV)
15
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 lownew 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...