Patent Application
20130307437
The present invention regards a charged particle accelerator operating in a solenoidal mirror magnetic field. And more specifically an accelerator that requires the particles have an initial azimuthal (magnetic moment) momentum, wherein the acceleration results in the particles being trapped against the minor gradient of the solenoidal mirror magnetic field by means of an axial electric field.
The present invention seeks to achieve the objective of providing a means and a method for the acceleration, confinement, trapping and neutralization of a population of stored charged particles in a magnetic field. Prior art references to the present disclosure, either in the scientific literature or in prior patents have not been found. Although the concept is simple and will be immediately evident to those with ordinary skill in the art.
This disclosure teaches certain benefits in construction and use which give rise to the objectives described below.
The Energy Density Intensifier provides a method and apparatus for accelerating, compressing, neutralizing and trapping a charged particle beam using a mirror solenoid having an axis of symmetry and supported within a vacuum space. A mirror magnetic field is generally weakest in the center and increases near the minor coils, where a generally radial component of the magnetic field appears. Charged particles having azimuthal momentum are confined radially by the axial magnetic field, but any axial momentum is not influenced by the axial component of the magnetic field. However, where the axial field increases (mirror field) a radial component of magnetic field exists. The radial component of the solenoid field exerts an axial acceleration to the azimuthal momentum, driving the particles away from the increasing field. Thus an azimuthal component of momentum is required for the axial force to develop on the particles. A generally axial electric field is introduced into the vacuum space generally between the particle entrance (source exit electrode) and an electrode established beyond the minor field, where the ions are not allowed to enter due to the interaction of their magnetic moments and the radial component of the minor magnetic field.
The objective of the present invention is to provide a means to increase the energy and the density and to trap charged particles stored in a magnetic field. The present invention does these functions as well as provide a means for space charge neutralization. The present invention operates on a basic principle of ion orbit physics that equates the magnetic moment and the axial momentum of the particle to the maximum magnetic field. In plasma physics the minor condition is when the energy of an ion is equal to the magnetic moment times the magnetic field, the charged particle can go no further up the magnetic field: ε=μB, where ε=energy, μ=mv2/2B, is the magnetic moment, and B is magnetic field strength, m is mass and v is velocity.
The present method allows for a further increase of an ion's energy if it initially has a non zero magnetic moment by drawing it deeper into a magnetic field than it's initial axial energy would allow. An added benefit arises because an ion drawn into a higher magnetic field has a smaller cyclotron radius: RL=mv/Bq, where q is the particle charge state. A smaller charged particle orbit radius increases the stored ion density because the cross sectional area of the stored charged particles is lower as A=πr2. The present declaration thereby increases both the energy and the density of a stored ion beam as well as providing ion trapping which has benefits to those fields of ion beams and plasma physics that endeavor to reach high energy densities for increased particle interaction rates.
A method and apparatus for accelerating, compressing, neutralizing and trapping an ion beam using a minor solenoid having an axis of symmetry and supported within a vacuum space is presented. Charged particles are assumed, previously introduced into the magnetic field possessing a magnetic moment, μ. Charged particles possessing a magnetic moment, that additionally have an axial momentum, parallel to the magnetic field will reflect off the minor component of the solenoid field, if the mirror magnetic field is adequate. Charged particles carrying a magnetic moment and moving into an increasing magnetic field experience a counteracting force due to the radial component of the magnetic field. As the solenoid field increases the azimuthal energy increases, E2=E1(B2/B1), at the expense of the axial energy. The spiral angle, θ, of the ion orbit is determined by the ratio of azimuthal to axial velocity,
where the subscripts m and M, indicate minimum and maximum values of the magnetic field. The point at which sin θM is unity, the velocity of the ion along the field line is zero, which is the minor reflection point. Thus an ion with both azimuthal and axial momentum exists in the central minimum in a mirror field the orbit will oscillate back and forth between the two mirror ends. The particle trajectory converts axial momentum into azimuthal momentum and then back to azimuthal as it approaches and recedes from the minor point. The increasing magnetic field increases angular momentum, Pφ=mωr,
so Pθ˜B, where, ω=2πfi, is radian cyclotron frequency. Because no work is done on the particle the total energy does not change so a gain in one component of energy reduces the other orthogonal energy. In addition to increasing the angular momentum the increasing magnetic field also reduces the orbit radius, increasing density,
where B1 and B2 are initial and final magnetic field strength, and RL1 and RL2 are Larmor radius in field B1 and B2 respectively.
The charged particles so established are acted upon by an electric field established within the solenoid field space, such as to draw the charged particles against the magnetic field gradient at the mirror end of the minor solenoid. The electrostatic field so established is introduced into the solenoid field region by any number of electrodes situated at any of a multitude of points or surfaces facing the vacuum confinement space. Such electrodes may be attached to the walls or facing components of the plasma vacuum space or suspended within the vacuum space. Such electrodes may be charged positive, negative or a varying potential may be applied to the various electrodes to establish any number of electric field geometries to achieved the intended objective. In a preferred embodiment the electrode is energized with a simple dc bias (electrostatic) and either attracts charged particles towards higher magnetic fields (negative electrode) or (positive electrode) repels charged particles away from the lower magnetic field. The electrostatic field may be applied beyond the minor point relative to the chamber wall anywhere in between the two ends of the solenoid. Thus the electrodes do not come into contact with the charged particles. The charged particles are drawn axially against the gradient of the increasing magnetic field along the axis, Z.
The intended objective of this accelerator and compressor is to cause the charged particles to become trapped against the gradient of the magnetic field. Acceleration of an ion, against the magnetic field gradient, overcomes the opposing force of the radial component of the solenoid field (in the region of increasing magnetic field). If an ion that initially has a rotational energy E1 in a magnetic field B1 is later found in a magnetic field B2, it follows from the conservation of magnetic moment that it will have an energy E2=E1(B2/B1). The ion is drawn into the magnetic field by the axial electric field until the radial component of the magnetic field counteracts the electric force, F=q(E+v×B), F=0=q(E−v×B) when E=−v×B. Thus the trapping condition is achieved.
This describes The Energy Density Intensifier for Accelerating, Trapping and Compressing Charged Particles in a Solenoid Magnetic Field and illustrates the apparatus and method of use in at least one of its preferred, best mode embodiments. Those having ordinary skill in the art may be able to make alterations and modifications to what is described herein without departing from its spirit and scope. Therefore it must be understood that what is illustrated is set forth only for the purpose of example and that it should not be taken as a limitation in the scope of the present apparatus and method of use.
Described now in detail is a method and apparatus useful for accelerating, compressing, neutralizing and trapping a charged particle beam.
The enablements described in detail above are considered novel over the prior art of record and are considered critical to the operation of at least one aspect of the apparatus and its method of use and to the achievement of the above described objectives. The words used in this specification to describe the instant embodiments are to be understood not only in the sense of their commonly defined meanings, but to include by special definition in this specification: structure, material of acts beyond the scope of the commonly defined meanings thus if an element can be understood in the context of this specification as including more than one meaning, then its use must be understood as being generic to all possible meanings supported by the specification and by the word or words describing the element.
The definitions of the words or drawing elements described herein are meant to include not only the combination of elements literally set forth, but all equivalent structure, material or acts of performing substantially the same function in substantially the same way to obtain substantially the same result. In this sense it is therefore contemplated that an equivalent substitution of two or more elements may be made for any one of the elements described and its various embodiments or that a single element may be substituted for two or more elements in a claim. Likewise any positioning of elements as literally set forth is to be recognized as being representative of an example to teach and that alternate positioning of elements performing substantially the same function obtaining to the same result are defined to be within the scope of the defined elements. Changes from the claimed subject matter as viewed by a person with ordinary skill in the art, now known or later devised, are expressly contemplated as being equivalents within the scope intended and its various embodiments. Therefore, obvious substitutions now or later known to one with ordinary skill in the art are defined to be within the scope of the defined elements. This disclosure is thus meant to be understood to include what is specifically illustrated and described above, what is conceptually equivalent, what can be obviously substituted, and what incorporates the essential ideas.
The scope of this description is to be interpreted only in conjunction with the appended claims and is made clear, here, that each named inventor believes that the claimed subject matter is what is intended to be patented.
