Explosively produced megagauss fields and applications

Faraday Rotation Measurements of Megagauss Magnetic Fields in Laser- Produced Plasmas

Observation of the decay dynamics and instabilities of megagauss field structures in laser-produced plasmas.

Monoenergetic proton radiography was used to make the first measurements of the long-time-scale dynamics and evolution of megagauss laser-plasma-generated magnetic field structures. While a 1-ns 10(14) W/cm2 laser beam is on, the field structure expands in tandem with a hemispherical plasma bubble, maintaining a rigorous 2D cylindrical symmetry. With the laser off, the bubble continues to expan...

Observation of megagauss-field topology changes due to magnetic reconnection in laser-produced plasmas.

The spatial structure and temporal evolution of megagauss magnetic fields generated by interactions of up to 4 laser beams with matter were studied with an innovative, time-gated proton radiography method that produces images of unprecedented clarity because it uses an isotropic, truly monoenergetic back-lighter (14.7-MeV protons from D3He nuclear fusion reactions). Quantitative field maps reve...

Measurement of the upper critical field of optimally-doped YBa2Cu3O7-δ in megagauss magnetic fields

We have observed crossover from superconducting state to normal state in optimally doped YBa2Cu3O7−δ (Tc ∼ 90 K) in very high magnetic fields (B) up to 600 T applied parallel to CuO2 planes (B⊥c). This is the first systematic critical field measurement at low temperatures in the geometry of the B‖CuO2-planes using superconductors with Tc greater than 90 K. In order to perform high-sensitivity m...

Self-generation of megagauss magnetic fields during the expansion of a plasma.

The expansion of a plasma slab into a vacuum is studied using one-dimensional and two-dimensional particle-in-cell simulations. As electrons transfer their longitudinal kinetic energy to ions during the expansion, the electron temperature becomes anisotropic. Once this anisotropy exceeds a threshold value, it drives the Weibel instability, leading to magnetic fields in the megagauss range. Thes...