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Induction Accelerators

TBA test assembly
TBA re-accelerator test assembly

The Two Beam Accelerator (TBA) is considered an option for a microwave power source for the Next Linear Collider (NLC) proposed by the Stanford Linear Accelerator group (SLAC). The basic idea of the TBA is that it may be possible to provide the microwave power for the NLC from a separate high-power electron beam located parallel to the high energy accelerator. As microwave power is extracted, the beam kinetic energy, nominally ~10 MeV, is reduced. Thus periodic re-acceleration of the high current beam is required to keep it at the nominal level until the beam quality suffers to the point where a new 10-MeV beam must be generated.

The prototype FMT Re-accelerator includes an induction module with a 150-kV accelerating gap, a high-power modulator to drive the induction module, and a high voltage power supply. This Re-accelerator is intended for use in the Relativistic-Klystron Two-Beam Accelerator (RTA) under development at the Lawrence Berkeley and Lawrence Livermore National Laboratories (LBNL and LLNL) . The RTA is a proof-of-principle experiment for the TBA concept and is a testbed for the associated technologies, in particular an efficient re-accelerator. The FMT unit is scheduled to be installed on the RTA beamline.

TBA Module
Two-Beam Accelerator (TBA) Module

The assembly pictured at right is an example of a custom research project developed by FMT and delivered to the Lawrence Berkeley National Laboratory. A high-power modulator (top) drives a series of 12 Metglas cores housed in the module (below) in such a way that the voltages from all of the cores add to provide up to 150 kV pulse to an electron beam traveling along the axis. The module, a prototype for an induction accelerator, is designed to accelerate a beam current of 700 amperes. It is considered an alternative for a multi-Gev microwave electron accelerator. The two beams refer to one low-energy, high-current beam driving, via periodic extraction of rf power, a high- energy, low-current beam. Inside the module is a carefully shaped high-voltage gap as well as periodic quadrupole strong focusing.


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