Gerald L. Kulcinski

Lunar Source of 3 He for Commercial Fusion Power

AbstractAn analysis of astrophysical information indicates that the solar wind has deposited an abundant, easily extractable source of 3He onto the surface of the moon. Apollo lunar samples indicat...

A review of 3He resources and acquisition for use as fusion fuel

This paper reports that a combination of man-made and natural resources on earth could provide sufficient {sup 3}He fuel for the technological development of D-{sup 3}He fusion reactors. Helium exists in natural gas wells; however, at the current rate of natural gas usage, this resource would provide {lt}5 kg/yr of {sup 3}He. The radioactive decay of {sup 3}H produced in fission production reactors could yield 110 kg of {sup 3}He by the year 2000 if it were retained. Apparently, a large amount of {sup 3}He exists within the earths mantle, but it is inaccessible. A significant quantity of {sup 3}He, which could be imported to supply a fusion power industry on earth for hundreds of years, exists on the moon. The solar wind has deposited {gt}1 million tonnes of {sup 3}He in the fine regolith that covers the surface of the moon. The presence of this solar wind gas was confirmed by analyses of the lunar regolith samples brought to earth. A strong correlation is noted between the helium retained and the TiO{sub 2} content of the regolith; consequently, remote-sensing data showing high-titanium-bearing soils in the lunar maria areas have been used to locate potentially rich sites for helium extraction.morexa0» Surface photographs of Mare Tranquillitatis have shown that nearly 50% of this mare may be minable and capable of supplying {approximately}7100 tonnes of {sup 3}He. A mobile mining vehicle is proposed for use in the excavation of the soil and the release of the helium and other solar wind gases. The evolved gases would be purified by a combination of permeators and cryogenic techniques to provide a rich resource of H{sub 2}, helium, CO{sub 2}, H{sub 2}O, and N{sub 2}, followed by helium isotopic separation systems.«xa0less

Summary of Apollo, a D-3He tokamak reactor design

AbstractThe key features of Apollo, a conceptual D-3He tokamak reactor for commercial electricity production, are summarized. The 1000-MW(electric) design utilizes direct conversion of synchrotron radiation power and thermal conversion of transport, neutron, and bremsstrahlung radiation power. The direct conversion method uses rectennas, and the thermal conversion cycle uses an organic coolant. Apollo operates in the first-stability regime, with a major radius of 7.89 m, a peak magnetic field on the toroidal field coils of 19.3 T, a 53-MA plasma current, and a 6.7% beta value. The low neutron production of the D-3He fuel cycle greatly reduces the radiation damage rate and allows a full-lifetime first wall and structure made of standard steels with only slight modifications to reduce activation levels. The reduced radioactive inventory and afterheat give significant safety and environmental advantages over deuterium-tritium reactors.

New Insight into Gridded Inertial Electrostatic Confinement (IEC) Fusion Devices

Abstract Gridded inertial electrostatic confinement (IEC) devices use a 10-200 kV voltage difference to accelerate ions through a 0.1-10 mTorr background gas in a spherical or cylindrical geometry. The detailed investigation of a gridded IEC device using DD fuel has resulted in several surprises that have greatly altered our perception of how these systems operate. It was found that there are at least 4 major misconceptions that have been in place for over 15 years on how such IEC systems operate. These misconceptions range all the way from what energetic ion is causing the majority of fusions, to the energy and charge state of the reacting ions. Experimental results will illustrate some of the surprising reactions that are taking place in DD gridded system.

Safety and Environmental Characteristics of Recent D- 3 He and DT Tokamak Power Reactors

A comparison of the key features of the D-He Apollo and the DT ARIES fusion power reactor designs is made. The reduction in neutron production from the D-He reaction has a major effect on the performance of tokamak reactors. One of the biggest impacts is the low radiation damage rate in D-He systems which allows a permanent first wall to be utilized. The reduction in radioactivity in D-3He reactors has a particularly advantageous effect on the storage of wastes as well as on the safety to the public in the event of the worst conceivable accident. The more difficult D-He physics requirements are offset by the technological advantages of using this fuel in place of the DT cycle.

Recent Advances in IEC Physics and Technology at the University of Wisconsin

Abstract The University of Wisconsin-Madison has conducted research on gridded inertial electrostatic confinement (IEC) devices for the past 18 years. There are currently 4 experimental devices operating at voltages up to 180 kV and 60 mA. These devices have uncovered several new phenomena that have greatly improved our understanding of IEC devices. Recent advances include the discovery of a significant negative ion component of DD plasmas and spatial profiles of fusion reactions that did not conform to our prior understanding of these devices. The use of this technology has also contributed to our understanding of surface damage to high temperature in-vessel W components after even low exposures to energetic He ion fluences. Expansion of the voltage-ion current parameter space to 300 kV-200 mA in the near future will help our understanding of advanced fusion fuel cycles.

Study of Thermionic Electrons in an Inertial Electrostatic Confinement Device Using a Novel “Chordwire” Diagnostic

Abstract Inertial electrostatic confinement devices can generate secondary, thermionic, photo, and field emission electrons from the cathode grid, which is a drain on the system. Of the various electron emission contributions, methods to study and minimize the thermionic emission current are explored in this paper using a new diagnostic called “chordwire” — wire placed in the form of a chord of a circle inside the cathode that intercepts particles. This chordwire intercepts particles and gets heated; the rise in temperature can be monitored externally using a pyrometer. Local power balance on the chordwires can then be used to infer the particle flux reaching the chordwires. This diagnostic helps show that to accurately estimate the ion current reaching the central grid, the thermionic electron emission has to be taken into account. The thermionic emission could become significant even for low power operation (<10 kW) in the presence of asymmetric grid heating. The asymmetric grid heating can be mitigated by homogenizing the ionization source around the chamber. The ion-recirculation current equation has been updated to accommodate the thermionic emission current. This ion-recirculation current equation shows that while the electron current increases nonlinearly with the power-supply current (when the grid is thermionically active for input power that is >10 kW), the ion current increases only in a less-than-linear fashion. Hence, the scaling of the fusion productivity with the power-supply current appears to be less than linear. Material selection and device operation should be aimed at reducing this electron energy drain for optimum performance. The overall thermionic emission from the cathode could be reduced through the selection of appropriate grid material with high work function (e.g., Re and W-25%Re). Moreover, this material also has lower sputter yield relative to Type 304 stainless steel, thus helping in high-voltage operation of the device.

Irradiation Behavior of Bonded Structures: Impact of Swelling-Creep-Stress Relationship

AbstractRadiation damage will be a major key point in the design of the many duplex components in fusion reactors. There is a substantial amount of available data showing that stress plays a major role in die onset, and possibly the rate, of void growth in austenitic stainless steels. There is also a strong support for models which predict a coupling of swelling and creep through the stress environment A parametric study for the stress-enhanced swelling and its connection to creep is conducted for a typical fusion power demonstration reactor.

Thin blanket design for MINIMARS - a compact tandem mirror fusion reactor

Recent fusion power reactor designs have shown a trend toward lower power, lower cost, higher mass utilization compact configurations with inherent safety, in order to improve the economic aspects of fusion and make them more competitive with other energy sources. Since the blanket thickness directly impacts the size and mass of the remaining reactor components, it is prudent to minimize its thickness while ensuring adequate neutronic and thermal performance. This paper describes the blanket for the MINI-MARS compact tandem mirror fusion power reactor. The blanket which utilizes HT-9 ferritic steel structure, LiPb breeder, Be multiplier/moderator and He gas cooling is only 17 cm thick and is backed up by a steel reflector. Helium gas cools the blanket and reflector in series and the outlet temperature of 575/sup 0/C gives a gross thermal power cycle efficiency of 42.7%.

Identification of Landmines and IEDs Using Compact Fusion Neutron Sources on Drones

Abstract This paper describes a system to detect landmines or IEDs by the use of small DD or DT neutron sources carried by a drone. The neutron source is powered by beaming RF or laser energy, at a distance of up to a km from the target, to a relay drone high (≈ 100 meters) above the neutron drone that converts the RF energy to electricity. The relay drone uses the electricity to generate another set of RF waves, and sends the energy down to the neutron drone to power the Inertial Electrostatic Confinement (IEC) fusion neutron generator. The neutrons emitted by the IEC generator interrogate the ground below the mobile neutron drone through neutron activation and the orbiting detector drones collect the gamma ray signals to determine the composition and location of the objects below. When the N/C/O signal is close to known chemical explosives signatures, the object is tagged for further investigation.