17 papers
Divergence Without Transition in Adiabatic Theory: Exact Cancellation in Reflectionless Potentials
Amitava Bhattacharjee
Adiabatic invariants play a central role in plasma physics, from magnetic moment and bounce action to wave action in slowly varying media. Their perturbative constructions are ofte…
Local relaxation and scale-dependent alignment in compressible, magnetized turbulence
James R. Beattie, Amitava Bhattacharjee
Driven net- and no-net-flux MHD turbulence simulations up to reveal sign-mixed velocity-magnetic, velocity-vorticity, and magnetic-current aligned patches below the en…
Optical analogy for stellarators: Ridges as caustics and coils as singularities
Wrick Sengupta, Stefan Buller, Rogerio Jorge +7
A common feature of most numerically optimized stellarator geometries is the presence of sharp ridges on outer flux surfaces, irrespective of the rotational transform. Despite thei…
Topological Arrest of Ballooning Modes in Non-Axisymmetric Plasmas
Amitava Bhattacharjee
Why do non-axisymmetric stellarators avoid ballooning crashes that afflict tokamaks? Three-dimensional geometry induces Anderson localization of ballooning modes, converting a glob…
Anderson Localization of Ion-Temperature-Gradient Modes and Ion Temperature Clamping in Aperiodic Stellarators
Amitava Bhattacharjee
Ion temperature clamping -- the saturation of the ion temperature regardless of heating power -- is observed across stellarator experiments. We propose a minimal model based on And…
Wave interference as the origin of the cyclic magnetorotational dynamo in accretion disks: insights from weakly nonlinear theory and local shearing box simulations
Uddipan Banik, Amitava Bhattacharjee, James M. Stone
Long-period cyclic reversals of the large-scale magnetic field are a prominent feature of the dynamo associated with the magnetorotational instability (MRI) in accretion disks, but…