| Research Abstract |
The primary task of the present investigation is to develop a plasma based electron linear accelerator, by exciting large amplitude electron plasma wave with high power, short pulse microwave. Specifically, the "VpxB acceleration scheme", which was found experimentally in our laboratory, should be employed, in addition to the large amplitude plasma wave wake field excited by the short microwave pulse. The above mentioned scheme should base on the variety of nonlinear phenomena occurring in the plasma, which also have to be investigated intensively.
Last two years, we stepped out the first step toward the goal of developing the plasma based electron linear accelerator. We, however, have faced to serious technical problem which should be broken through very urgently. That is, the ultra-short, high power microwave pulse is required. The typical specifications follow, 1 nsec FWHM with 50-100 kW peak power at f= 2.86 GHz or 0.5 nsec FWHM 250-500 kW peak power at f = 9.5 GHz. The basic idea for this system is now under development in our laboratory, still we need much time for use in the experiments. This is one of the key issues for the next several years.
We have found new phenomena such as large amplitude (deltan/n (] SY.gtoreq.[) 40 %) ion wave excitation by a short microwave pulse with typical pulse width of 70 nsec or less and an observation of temporal plasma wave echoes which has been expected for last 25 years after the first theoretical prediction in 1967.
We have developed electron linear accelerators based on the VpxB scheme in vacuum for aiming to develop the compact, high efficiency, high acceleration gradient accelerators. We employed the longitudinal mode electro-magnetic wave produced by the disk shaped electrode for the delay circuit. The vertical static magnetic field is applied for making the VpxB scheme. We have succeeded to accelerate electrons in the above mentioned new scheme.
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