The first serious Long term study of coaxial accelerators (originally called TLA - transport linear accelerator, later called a mass driver) began with the efforts of Prof. Gerard K. O'Neill and Dr. Henry H. Kolm for use in space colonization and industrialization studies 1974-1976. Since then a large number of papers have been written and published by this Princeton - M.I.T. group on mass drivers and their applications, see Appendix A. Originally, mass drivers were of a planar geometry for use as a lunar launcher. Later it was found that a coaxial geometry gave much better coupling (factor of 2) and thereby better performance. However, this coaxial geometry reduced the flexibility of the bucket to contain and release payloads. Since 1974, the mass driver has gone through a number of changes in its geometry, number of phases, number of bucket coils, kind of bucket coils, guidestrips, and overall configuration and this process is still continuing. The planar geometry lunar launcher contained a three phase drive circuit and a bucket with two superconducting bucket coils. This was very close to the design of the M.I.T. Magneplane so that calculations on the design could be checked with their experimental results. The first coaxial mass driver design also contained three phases in its push-pull drive circuit but it had four superconducting bucket coils. At this time a simplified mass driver was constructed to demonstrate some of their features. Mass Driver One was constructed during the winter and spring of 1977 at M.I.T. It was a quarter cycle push only accelerator with 20 drive coils individually fed by an electrolytic capacitor. The bucket was ohmic (not superconducting) and had sliding brush contacts to obtain power. After the successful testing of Mass Driver One, further work on mass drivers continued at the 1977 Ames Summer Study. Improvements in
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