Velocity-space tomography of accretion discs and in fusion plasmas

 

Integrated data analysis of fast-ion measurements has long been hampered by the complexity of the strongly non-Maxwellian fast-ion distribution functions. This has recently been overcome by velocity-space tomography. This method has been used in the astrophysical community to study the structure of accretion discs for more than 20 years. In this method 2D images of velocity distribution functions consisting of a few hundreds or thousands of pixels are reconstructed using the available measurements by tomography inversion. Here we discuss the analogy between the astrophysical and fusion flavors of the method and present an overview of this emerging technique using examples from the tokamaks ASDEX Upgrade and JET.