PUFFIN is designed to deliver an intense pulse of electrical current to a “load”, and arrangement of thin wires or foils which are rapidly converted into hot, dense plasma. PUFFIN is built around the LTD5 modules developed at CEA Gramat. LTDs are Linear Transformer Drivers, a relatively new pulsed-power technology which encloses the capacitive energy store and switch in a single conducting cavity. This reduces the inductance of the system and shields external equipment from the electromagnetic pulse.

PUFFIN’s unique capability is its microsecond pulse length, in contrast to fast rise-time LTD pulsers such as MAIZE and HADES, which drive rapid implosions to reach extreme conditions. Instead, the longer pulse length on PUFFIN allow us to sustain plasmas in a quasi-steady-state, which is ideal for studying fundamental plasma processes.

Construction of PUFFIN was completed at the MIT PSFC in November 2024. The two LTD5 modules, along with the charge-and-dump, pre-magnetisation, and switch trigger systems arrived at the PSFC in May 2022. Refurbishment of the lab space in the West Cell of the PSFC (MIT building NW21) finished in Fall 2022, and the design phase for PUFFIN finished in March 2023. Construction of the major components was completed by the end of 2023, and assembly and commissioning continued for another year, with all the necessary tweaks required to build a first-of-a-kind machine. Further updates can be found on our News page.

PUFFIN consists of 2 LTD5 modules (consisting of two 3.9 uF, 100 kV Haefly capacitors) coupled to two coaxial vacuum transmission lines (200 mm OD, 20 mm gap) by multi-channel low-inductance switches insulated by atmospheric pressure dry air. The transmission lines merge at the power junction and transmit the current upwards into the vacuum chamber.

The vacuum chamber has 16 sides with configurable vacuum ports to enable a range of diagnostics to be fielded, including interferometry, Thomson scattering and Faraday rotation imaging. There is also a clear line of sight axially through the load.

Construction photos

Further Reading