High current, low emittance, steady state electron guns with plasma cathodes

Major limitations of plasma cathodes have been overcome in an electron gun based on extraction of superthermal electrons from a discharge characterized by a large component of high energy electrons with a low thermal spread. A grid is employed to select these electrons for extraction while retaining the bulk electrons in the discharge. Steady state extraction of electron beams corresponding to over 60% of the total arc discharge current has been observed. A perveance of over 280 microperv was reached with the extraction of 9A at 1 keV from a 6 nun aperture. Some of the characteristics of the electron beam described in this paper are very attractive for electron beam melting

R&D ERL: Beam Dump

As its name suggests, the beam dump is where electron bunches end up while depositing energy unrecovered by the ERL. The process of removing unrecovered energy must not have any adverse effects on the ERL system like outgassing or backstreaming electrons. Electron beam dumps are widely used in various applications ranging from radiation generating devices like klystrons and traveling wave tubes to EBIS sources and electron beam coolers, as well as to large machines that include LINACs and electron colliders. Energy of discarded electrons range from a few electron volts to 10's of GeV. This beam dump has a couple of unique issues that determine the design concept: cascade showers and seals that can withstand high radiation dosage

R&D ERL: Beam Dump

As its name suggests, the beam dump is where electron bunches end up while depositing energy unrecovered by the ERL. The process of removing unrecovered energy must not have any adverse effects on the ERL system like outgassing or backstreaming electrons. Electron beam dumps are widely used in various applications ranging from radiation generating devices like klystrons and traveling wave tubes to EBIS sources and electron beam coolers, as well as to large machines that include LINACs and electron colliders. Energy of discarded electrons range from a few electron volts to 10's of GeV. This beam dump has a couple of unique issues that determine the design concept: cascade showers and seals that can withstand high radiation dosage

PLASMA WINDOW FOR VACUUM - ATMOSPHERE INTERFACE AND FOCUSING LENS OF SOURCES FOR NON-VACUUM MATERIAL MODIFICATION.

Material modifications by ion implantation, dry etching, and micro-fabrication are widely used technologies, all of which are performed in vacuum, since ion beams at energies used in these applications are completely attenuated by foils or by long differentially pumped sections, which ate currently used to interface between vacuum and atmosphere. A novel plasma window, which utilizes a short arc for vacuum-atmosphere interface has been developed. This window provides for sufficient vacuum atmosphere separation, as well as for ion beam propagation through it, thus facilitating non-vacuum ion material modification

INVESTIGATION OF A PLASMA MODE IN EBTS.

A plasma related mode has been identified when EBTS operated with long trap length. The mode frequency scaling showed monotonic increased with confinement time. Initial scaling qualitatively suggested the mode to an electron beam driven ion cyclotron instability. However, a more quantitative evaluation is indicative of a drift mode. Nevertheless, the possibility of a structure mode, though unlikely, can not be completely excluded. The process of proper instability identification and stabilization is described

Energy Recovery Linac: Beam Dump

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Emittance Reduction between EBIS LINAC and Booster by Electron Beam Cooling; Is Single Pass Cooling Possible?

Electron beam cooling is examined as an option to reduce momentum of gold ions exiting the EBIS LINAC before injection into the booster. Electron beam parameters are based on experimental data (obtained at BNL) of electron beams extracted from a plasma cathode. Preliminary calculations indicate that single pass cooling is feasible; momentum spread can be reduced by more than an order of magnitude in less than one meter

High current magnetized plasma discharges and electron beams for capture and cooling of charged leptons and hadrons

Nowadays most magnetic lenses used to capture and to focus pions and muons utilize azimuthal magnetic fields generated by large axial currents, like horns or lithium rods (or even a Z-pinch at GSI). Capture and focusing angle is proportional to the product of the current and length of the lens. State-of-the-art for these lenses is no more than 750 kA and 70 cm. A meter long, multi-MA, magnetized axial discharges were generated by the early days of fusion. Lenses based of such devices can increase the capture angle of pions, e.g., by more than a factor of 2. Electron beam cooling is presently achieved in storage rings by having charged particles interact with a co-moving electron beam. In these devices, typical parameters are electron beam currents of about 1 A, an interaction length of about 1 meter, and interaction time of about 30 msec. Multi-MA electron beams can be used for single-pass final stage cooling in a number of machines. Calculations for some applications, as well as other advantages indicate that these schemes deserve further more serious consideration

Review of electron beam macroinstabilities and other EBIS related stability and issues

Plasma magnetohydrodynamics and macro-instability theories are briefly reviewed. Although the configuration of any EBIS is inherently susceptible to a number of classical beam instabilities, the small radial dimension of an EBIS plasma prevents modes from occurring in EBIS traps with low beam compression due to physical limitations. In EBIS devices with high electron beam compression, where the potential for beam instabilities is great, the radial dimension is smaller than the Debye length, which renders any plasma theory invalid. However, a RHIC EBIS is expected to have a diameter which is much larger than the Debye length. Hence, it may be the first EBIS, in which the various plasma theories could be valid. For this and future devices like it, a framework is established to analyze and offer remedies plasma instabilities in EBIS

Compact, energy EFFICIENT neutron source: enabling technology for various applications

A novel neutron source comprising of a deuterium beam (energy of about 100 KeV) injected into a tube filled with tritium gas and/or tritium plasma that generates D-T fusion reactions, whose products are 14.06 MeV neutrons and 3.52 MeV alpha particles, is described. At the opposite end of the tube, the energy of deuterium ions that did not interact is recovered. Beryllium walls of proper thickness can be utilized to absorb 14 MeV neutrons and release 2-3 low energy neutrons. Each ion source and tube forms a module. Larger systems can be formed from multiple units. Unlike currently proposed methods, where accelerator-based neutron sources are very expensive, large, and require large amounts of power for operation, this neutron source is compact, inexpensive, easy to test and to scale up. Among possible applications for this neutron source concept are sub-critical nuclear breeder reactors and transmutation of radioactive waste