Development of beam position monitors for heavy ion recirculators
Work is underway at the Lawrence Livermore National Laboratory to design and build a small-scale, heavy ion recirculating induction accelerator. An essential part of this design work is the development of small non-intercepting diagnostics to measure beam current and position. This paper describes some of this work, with particular emphasis on the development of a small capacitive probe beam position monitor to resolve beam position to the 100 /spl mu/m level in a 6 cm diameter beam pipe. Initial measured results with an 80 keV potassium ion beam are presented.
Development of a resistive beam position/current monitor for the UMD electron ring
A prototype resistive beam position/current monitor has been developed for the proposed small electron ring at the University of Maryland. It consists of 32 low-inductance resistors which are uniformly distributed around a ceramic gap between two conducting pipes. The resistors are divided into four quadrants and each quadrant has a total resistance of 0.625 /spl Omega/. The beam image currents are measured in the four quadrants and the measurement leads to the information about beam position and total beam current. A bench test has been done for the prototype beam position/current monitor. The result shows that the beam position/current monitor gives an accurate total beam current with an error of 2% and satisfactory position information in both radial and azimuthal directions. The rise time of the monitor is measured to be about 1 ns.
An applied voltage to eliminate current transients in a one‐dimensional diode
Development of sources for heavy ion fusion motivates study of diode current transients. For the one‐dimensional problem a unique applied voltage eliminates transients in the space‐charge‐dominated case:V(t)=V[4/3 (t/τ)−1/3 (t/τ)4] for t<τ, V(t)=V for t≥τ, where L is diode length, V is steady state diode potential, q/m is charge to mass ratio, and τ=3L(m/2qV)1/2 is a particle transit time through the diode. We derive this result and compare it to computer simulations and experimental results.