The Spherical Theta Pinch and its applications

Summary form only given. The Spherical Theta Pinch was developed at the Institute for Applied Physics at the Goethe University Frankfurt. It consists of a spherical coil with less than 10 windings which are arranged around a glass vessel with a volume of several liters. A capacitor bank is discharged trough a self-developed thyristor stack. The rising current in the coil ionizes the gas inside the glas vessel and the magnetic fields compress the plasma on the symmetry axis. Due to the spherical assembly the pinch is more stable than in common linear theta pinch machines.¹ The capacitors and the coil form a LCR-circuit with a resonance frequency of around 10kHz, the stored energy in the capacitors reaches 5kJ at a voltage of 15kV and the maximum currents are 8kA.After the development of several prototypes and intense e,amination, the first theta pinch device was now tested as a plasma stripper at the GSI facility, Darmstadt. For reaching higher charge states of ions, which minimize the acceleration distance, stripping foils are used at the moment. As these foils bear several mechanical and technical problems and furthermore only allow a small increment of the charge state, stripping plasmas have been proposed as an alternative. Compared to formerly used Z-pinches the theta pinch has the advantage of almost unlimited lifetime, as no electrodes are in contact with the plasma discharge and could thus erode. Other applications which are investigated are the generation of intense VUV-pulses and the use as a pulsed high current H+ ion source.