Publications

Laser and Particle Beams

Renk, T.J.; Mann, Gregory A.; Torres, G.A.

For operation of an ion source in an intense ion beam diode, it is desirable to form a localized and robust source of high purity. A cryogenically operated ion source has great promise, since the ions are formed from a condensed high-purity gas, which has been confined to a relatively thin ice layer on the anode surface. Previous experiments have established the principles of operation of such an ion source, but have been limited in repetitive duration due to the use of short-lived liquid He cooling of the anode surface. We detail here the successful development of a Cryo-Diode in which the cooling was achieved with a closed-cycle cryo-pump. This results in an ion source design that can potentially be operated for an indefinite duration. Time-of-flight measurements with Faraday cups indicate that the resultant ion beam is of high-purity, and composed of singly charged ions formed out of the gas frozen out on the anode surface. © 2008 Copyright Cambridge University Press 2008.

Chhabildas, Lalit C.; Trott, Wayne T.; Reinhart, William D.; Mann, Gregory A.

Abstract not provided.

Kaye, Ronald J.; Kaye, Ronald J.; Mann, Gregory A.

Coilguns have demonstrated their capability to launch projectiles to 1 km/s, and there is interest in their application for long-range precision strike weapons. However, the incorporation of cooling systems for repetitive operation will impact the mechanical design and response of the future coils. To assess the impact of such changes, an evaluation of the ruggedness and reliability of the existing 50 mm bore coil designed in 1993 was made by repeatedly testing at stress levels associated with operation in a coilgun. A two-coil testbed has been built with a static projectile where each coil is energized by its own capacitor bank. Simulation models of the applied forces generated in this testbed have been created with the SLINGSHOT circuit code to obtain loads equivalent to the worst-case anticipated in a 50 mm coilgun that could launch a 236 g projectile to 2 km/s. Bench measurements of the seven remaining coils built in 1993 have been used to evaluate which coils were viable for testing, and only one was found defective. Measurements of the gradient of the effective coil inductance in the presence of the projectile were compared to values from SLINGSHOT, and the agreement is excellent. Repeated testing of the HFC5 coil built in 1993 has demonstrated no failures after 205 shots, which is an order of magnitude greater than any number achieved in previous testing. Although this testing has only been done on two coils, the results are encouraging as it demonstrates there are no fundamental weak links in the design that will cause a very early failure. Several recommendations for future coil designs are suggested based on observations of this study.