Progress and plans of the proto-sphera program

S. Papastergiou, F. Alladio, A. Cucchiaro, A. Mancuso, P. Micozzi

Research output: Contribution to conferencePaper

2 Citations (Scopus)


PROTO-SPHERA is a proposed spherical torus (ST) where a Hydrogen plasma arc, in a form of a Screw Pinch (SP), fed by electrodes, replaces the central rod of the standard ST experiments, This machine, with a longitudinal pinch current Ie=60 kA, will produce an ST of diameter 2Rsph=75 cm, aspect ratio A=1.2-1.3, carrying a toroidal current Ip=120-240 kA. The plasma will be magnetically shaped as a disk near each modular annular electrode. Theoretical calculations (using a 3D ideal MHD stability code) show that such a configuration should be ideally stable up to a total beta ranging between 15-25%, depending upon the ratio Ip/Ie. The ST toroidal current should be sustained by Helicity Injection from the Screw Pinch. In order to demonstrate the feasibility of the SP discharge and the basic electrode characteristics, a preliminary linear electrode test bed, Proto-Pinch, has been built and operated successfully. The detail mechanical engineering design of PROTO-SPHERA has now been completed. The machine design philosophy, basic geometry and operating conditions with the major components like the vacuum vessel (VV), coils, electrodes, protection components and divertor will be analysed. The thermal and electromagnetic behaviour as well as the predicted and permitted heat stresses will be discussed in order to demonstrate that the design, construction and reliable operation of the machine are feasible. Reference is also made to the proposed Multi-Pinch experiment using the START VV to demonstrate the feasibility and stability of the PROTO-SPHERA configuration. The START W has now been transported and disassembled in ENEA-Frascati. The detailed design of Multi-Pinch, initial phase of PROTO-SPHERA, has also been completed and the first contract related to the PF coils has been placed. © IEEE.
Original languageEnglish
Publication statusPublished - 2006
Externally publishedYes
Event21st IEEE/NPS Symposium on Fusion Engineering, SOFE'05 - , United States
Duration: 1 Jan 2006 → …


Conference21st IEEE/NPS Symposium on Fusion Engineering, SOFE'05
CountryUnited States
Period1/1/06 → …


All Science Journal Classification (ASJC) codes

  • Nuclear and High Energy Physics
  • Nuclear Energy and Engineering

Cite this

Papastergiou, S., Alladio, F., Cucchiaro, A., Mancuso, A., & Micozzi, P. (2006). Progress and plans of the proto-sphera program. Paper presented at 21st IEEE/NPS Symposium on Fusion Engineering, SOFE'05, United States.