Design of a Thomson parabola spectrometer for the detection of laser-accelerated protons and ions

Very intense pulses of protons and ions can be produced in laser-plasma interactions at ultra-high energy densities. In a Thomson parabola spectrometer (TPS) the accelerated particles are separated by their mass, charge, and momentum. We present the design of a TPS for the spectral characterization of laser-accelerated protons and carbon ions which will be implemented in a table-top laser setup which is currently under preparation. First estimates of the magnetic and electric fields as well as the particle flight paths necessary for the clear separation of particle momenta have been obtained from well-known equations. We have designed a pair of permanent magnets with a C-shaped yoke to achieve a field of the order of 0.54 T. An exact field map has been obtained from simulations with COMSOL Multi-physics. The same software has been used to simulate the electric field between charged copper plates and the depletion of particles in the entire detector system. Our versatile setup allows for adjusting the desired energy range by variation of the position of the detector plane and the field gradient of the electric field. In the case of protons the low-energy interval ranges from 100 to 1000 keV, and the high-energy interval, from 1 to 10 MeV. Carbon ions can be separated by charge and momentum in both configurations.