Nuclear Fusion in Inertial Electrostatic Confinement devices Whats

Nuclear Fusion in Inertial. Electrostatic Confinement devices: What’s really going on underneath the sheets? By Nico Ranson The University of Sydney Page 1

Usyd Applied Plasma Physics Fusion Group. - Myself. Supervisor Joe Khachan Richard B. R. (Dr? ) Daan van Schinjdel (Honours) A regular stream of Dutch trainees 2 labs, 3 devices. Plenty of space for new research projects You? The University of Sydney Page 2

Fusion Basics The University of Sydney Page 3

Inertial-Electrostatic Confinement D(d, n)3 He The University of Sydney - Ions accelerated inwards - High density at cathode centre - Fusion assumed to be ion-gas - Grid represents losses Page 4

Ion energy and Spectroscopy Fig: Doppler Spectra against cathode voltage in IEC – Ions undergo charge exchange – Doppler shift: – Resulting ion energy: Khachan, J. et. al: (2001) Measurements of ion energy distributions by Doppler shift spectroscopy in an inertial electrostatic confinement Device. Physics of Plasmas (1070 -664 X), 8, (4), p. 1299 The University of Sydney Page 5

IEC in operation The University of Sydney Page 6

Hollow Cathode Discharge Fig: A biconical hollow cathode – Produces strong, directional ion beam ⇒ Doppler analysis easier than in IEC device. – Used for sputtering deposition, electron and ion beams. The University of Sydney Page 7

Trouble in Paradise! - Problem of irreducibility between experiments. Why? - Plasma complex, many assumptions necessary. - Chamber geometry, cathode material, some aspects of cathode geometry etc assumed unimportant. - What other assumptions incorrect? The University of Sydney Page 8

My Honours Project - Quantify and explain why cathode geometry matters so much. The University of Sydney Page 9

Fusion rate (s^-1) Size DOES matter The University of Sydney Page 10

Ambipolar fields: The hidden suspect 1. e- Electrons leave system e- r eee- e 2. +ve space Charge created The University of Sydney 3. Ions diverge from cathode centre Page 11

Ambipolar Field Equation - Steady state fluid equations valid for IEC plasma bulk The University of Sydney Page 12

Matching my experimental results The University of Sydney Page 13

Matching other experiments . Motoyasu, S. Namba, and K. Takiyama. Measurements of localized potential profiles by lif polarization spectrsocopy in an inertial-electrostatic confinement discharge. Journal of the Korean Physical Society 65(8): 1205– 1208, 2014 The University of Sydney Kipriditis et al. Absolute densities of energetic hydrogen ion species in an abnormal hollow cathode discharge. Physical Review E, 77, 066405 (2008) Page 14

Next Challenge - Argon ion measurements using LIF spectroscopy - Sheath effect or ambipolar field effect? We think ambipolar field The University of Sydney Page 15

Thanks for your time! - Any help on getting sheath appreciated - If you’re interested in a project, contact nicholas. ranson@sydney. edu. au The University of Sydney Page 16