Patent Number: 042773059
Section: summary

BACKGROUND OF THE INVENTION The present invention pertains generally to plasmas and more specifically to devices for generating thermonuclear neutrons. Prior art methods for generating hot plasmas have been limited to inertially and magnetically confined systems. A typical example of an inertially confined system is the implosion of fuel microcapsules by impingent high power laser or electron beams. Typical examples of magnetically confined systems comprise theta-pinch devices, Z-pinch devices, various toroidal configurations such as stellarators, syllacs tokomacs, and toroidal Z-pinch devices, which form a magnetic bottle to confine a hot plasma for a predetermined period at sufficiently high temperatures and pressures to produce thermonuclear neutrons. Both the inertially confined systems and the magnetically confined systems have various disadvantages and limitations. In both types of systems it is difficult and expensive to bring to bear sufficient energy on the hot plasma to insure significant thermonuclear burn. End losses in linear theta-pinch devices and various instabilities defeating confinement in other magnetic confinement systems due to rapid growth relative to containment times, also result in limited burn of the thermonuclear plasma. Damage to inertial confinement targets prior to implosion due to deposition of beam energy directly on the fuel element also limits neutron yield. This has been alleviated somewhat by pulse shaping and limiting the duration of the beam pulse. However, these measures impose extreme design limitations on the beam pulse generator which typically reduce efficiency. Moreover, the necessity of beam focusing to fuel microcapsule diameters requires expensive and easily damaged optics. Additionally, absorption characteristics of fuel microcapsule for impingent laser beams does not provide a good impedance match to insure maximum deposition of energy. Although magnetic confinement systems protect the containment vessel by magnetic energy fields and provide a means for recovering magnetic energy during fuel expansion, such systems are not inherent to inertially confined systems and must be added separately. SUMMARY OF THE INVENTION The present invention overcomes the disadvantages and limitations of the prior art by providing a beam heated linear theta-pinch device for producing hot plasmas. According to the present invention, both magnetic and beam energy are utilized to supplement each other to produce a hot plasma. The implosive nature and rapid burn characteristics of the present invention eliminate end loss and plasma instability problems associated with magnetically contained systems. Since the beam energy is not directed at the fuel microcapsule but rather at a surrounding plasma, problems of fuel target damage, beam focusing, pulse shape and duration, and energy absorption properties are alleviated. Moreover, the magnetic field of the linear theta-pinch device of the present invention protects the cylindrical walls from the microexplosion and allows magnetic energy to be recovered during fuel expansion as well as providing a simple cylindrical geometry minimizing construction and operational difficulties. It is therefore an object of the present invention to provide a device for generating a hot plasma. It is also an object of the present invention to provide a device for generating thermonuclear neutrons. Another object of the present invention is to provide a device for generating hot plasmas which is simple in operation and easy to implement. Another object of the present invention is to provide a device for producing hot plasmas which is inexpensive to implement. Another object of the present invention is to provide a device for generating hot plasmas which overcomes the disadvantages and limitations of inertial confinement systems. Another object of the present invention is to provide a device for producing hot plasmas which overcomes the disadvantages and limitations of inertial confinement systems. Other objects and further scope of applicability of the present invention will become apparent from the detailed description given hereinafter. The detailed description, indicating the preferred embodiments of the invention is given only by way of illustration since various changes and modifications within the spirit and scope of the invention will become apparent to those skilled in the art from this detailed description. The foregoing Abstract of the Disclosure is for the purpose of providing a nonlegal brief statement to serve as a searching and scanning tool for scientists, engineers, and researchers and is not intended to limit the scope of the invention as disclosed herein, nor is it intended to be used in interpreting, or in any way limiting, the scope or fair meaning of the appended claims.