Abstract: An electrostatic particle beam combiner for creating a single source combining the properties of two particle beams which form a high brightness source of a selected mixture of ions of varying element types and energies. An electrostatic spherical lens is arranged to bend a low energy second particle beam along a circular path and thereafter to impinge on a surface of a sample, e.g., within a transmission electron microscope. A beam of high energy is injected into the electrostatic spherical lens through an aperture in the outer shell and steered by two spaced apart electrostatic deflectors so that the angle of entry and the point of entry can be independently adjusted so that the high energy beam leaves the spherical lens along a path which is coaxial and coincident with the second particle beam of low energy.

Abstract: A method and apparatus for measuring the beam current of a particle beam in an accelerator by charging the capacitor across an operational amplifier and controlling the scaling of the amplifier output with a programmable gain amplifier (PGA). The out put of the (PGA) is sampled and storing with an analog-to-digital converter to acquire and store at least two digital voltage values. The two digital voltage values are using to obtain a value proportional to beam current. A field programmable gate array is used to implement digital logic to sample and hold output from the analog-to-digital converter.

Abstract: A negative ion source placed inside a negatively-charged high voltage electrode emits a beam which is accelerated to moderate energy, approximately 35,000 electron volts, and filtered by a momentum analyzer i.e. an analyzing bending magnet, to remove unwanted ions. Reference ions such as carbon-12 are deflected and measured in an off-axis Faraday cup. Ions of interest, such as carbon ions of mass 14, are accelerated through 300 kV to ground potential and passed through a gas stripper where the ions undergo charge exchange and molecular destruction. The desired isotope, carbon-14 along with fragments of the interfering molecular ions, emerge from the stripper into a momentum analyzer which removes undesirable isotope ions. The ions are further filtered by passing through an electrostatic spherical analyzer to remove ions which have undergone charge exchange. The ions remaining after the spherical analyzer are transmitted to a detector and counted.

Abstract: An ion source employs a self-contained sample containment valve which serves to store, transport and dispense a gas sample from which a negative ion beam is generated. The valve is loaded with a sample of carbon dioxide gas by cryo-pumping carbon dioxide gas into a finger which is refrigerated with liquid nitrogen and which is connected to the stored volume of the valve. A sample contained in the gas containment valve is combined with a total of forty sample containment valves on a carousel which is mounted adjacent to the cathode of a negative ion source of a tandem accelerator facility within a vacuum chamber. When a particular sample containment valve is aligned with the cathode an actuator causes the sample containment valve to move forward a short distance positioning the valve to dispense gas to generate a negative carbon ion beam. When changing the samples contained on the carousel, the ion source must be shut off from the vacuum chamber. This is accomplished by interposing a gate valve.

Abstract: A hydrogen ion accelerator produces a beam current that is at least ten times greater than the current supplied by an electrostatic generator by recycling the unreacted portion of the beam. In one application, a 1.76 MeV proton beam is used to generate 9.172 MeV gamma rays for detecting explosives (nitrogen) via either the .sup.13 C reaction. The cross-section of the 1.76 MeV proton beam with the carbon 13 target is such that over 95 percent of the beam passes through the target unreacted. In a preferred embodiment, a proton source (52) disposed within a high voltage electrode (32) forms a proton beam that is accelerated along the length of an acceleration tube (46), is bent 180.degree. by bending magnets (70, 72), passes through a target foil (76), is decelerated along the length of a deceleration tube (82), and is returned to the high voltage electrode (32) where the energy contained in the beam is recaptured.

Abstract: An apparatus employs two spaced apart dipole magnets. An ion beam containing carbon of mass 2, 13 and 14 is focused by an Einzel lens and is directed into a first dipole magnet. The first magnet causes the beam to bend approximately 70 degrees, which separates the mass 12, 13 and 14 ions while at the same time focusing them in the X direction or deflection plane. The ions exit the first dipole magnet and pass through a blanking plate which can selectively remove one or two of the beams of mass 12, 13 and 14 ions. After leaving the first bending magnet, the mass 12 and 14 beams pass through a steering device so the trajectories of the mass 12 and 14 ions are deflected a few degrees to bring them parallel to the mass 13 ion beam. The parallel ion beams next pass through an electrostatic slot lens which focuses the beams in the direction out of the bending plane. After passing through the slot lens, the mass 12 and 14 beams are deflected in like amount to the deflection at the first steering device.

Abstract: The high voltage electrostatic accelerator of this invention has spark arrester rings which form magnetic shield elements around an acceleration tube and which together with mu-metal rings between accelerator segments shield the electrons being accelerated from stray static and dynamic magnetic fields. The spark arresters surround the accelerating electrodes. The rings between accelerator segments are formed of mu-metal, an alloy of nickel designed for its magnetic shielding properties and consisting of 77 percent nickel, 4.8 percent copper, 1.5 percent chrome and 14.9 percent iron. The mu-metal spark arresters together with the rings between accelerators segments provide an effective magnetic shield in a cost-effective manner. Because mu-metal has a high permeability, magnetic field lines tend to travel about the Mu-metal rings rather than pass through the acceleration tube, where they would influence electrons being accelerated.

Abstract: An impulse valve for an ion source is positioned between an ion source chamber and a gas metering valve. The impulse valve is a two-position solenoid-controlled valve which is closed in its off position. In the off-position, the valve forms a reservoir between the valve stem of the impulse valve and the metering orifice of the metering valve. In the off condition, the gas reservoir fills with gas that over time equilibrates to the pressure of the gas supplied to the metering valve. The volume of the gas reservoir and the pressure of the gas which is supplied to the metering valve are chosen so that when the two-position valve is open, the gas contained in the reservoir is sufficient to pressurize the ion source chamber to a pressure of approximately 0.1 Torr. Thus, when the impulse valve opens, a pulse of gas flows into the ion source chamber, where a plasma discharge is initiated.

Abstract: A uniform ion implantation dose control apparatus controls the implantation of ion particles onto at least one wafer mounted on a rotating disk in the pathway of the ion particle beam. A grounded scanning wire is repeatedly moved across the beam to produce an emission of secondary electrons which is linearly proportional to the beam particle current. The secondary electrons emitted are collected and formed into a current I.sub.s by a collector electrode. Portions of the current I.sub.s on the collector electrode are sampled. While the vacuum conditions within the beamline are good, the beams electrical current I.sub.FC is measured and the collector current I.sub.s sample is calibrated therewith so that when the beamline vacuum becomes a high pressure vacuum, additional collector current I.sub.s samples may be utilized to determine a theoretical beam current I which is a function of the beam particle current I.sub.p =I/q.