M9: Fast Particle Physics (FPP) Experiments

1. Ken McClements & Sergei Sharapov on behalf of all contributors to FPP programme on MAST M9: Fast Particle Physics (FPP)Experiments Ken McClements: MAST Team Meeting

2. M9 headlines • ELM control with 3D magnetic perturbations • Evolution and stability of the edge pedestal • Role of ion-scale turbulence in core transport • Development of integrated scenarios for the MAST upgrade • Development and benchmarking of edge modelling tools in benefit of the divertor upgrade • Fast-ion transport to guide profile and heating optimisations Ken McClements: MAST Team Meeting

3. Proposal process • 14 proposals submitted in FPP programme area (including 5 originally submitted in Integrated Plasma Scenario area) • ~200 shots requested in total • Merging & prioritisation has resulted in: • 5 main experiments, allocated 110 shots • 4 parasitic experiments (1 of these is also a main experiment) • 0 backup experiments Ken McClements: MAST Team Meeting

4. Main experiments Ken McClements: MAST Team Meeting

5. Parasitic experiments Ken McClements: MAST Team Meeting

6. ITPA contributions Two experiments (TAE avalanches, effect of RMPs/ELMs on fast ion losses) will contribute to ITPA experiments: • EP-2: Fast ion loss & redistribution from localised AE • EP-6: Fast-ion losses & associated head load from edge perturbations (ELMs & RMPs) Ken McClements: MAST Team Meeting

7. M9-FPP-001: fusion proton detector • Aim • Use fusion proton detector (provided by Florida International University) with neutron camera to study changes in fast ion population resulting from short timescale MHD activity (fishbones, sawteeth) & NBI blips • Protons detected more efficiently than neutrons, hence proton detector can in principle provide improved time resolution • Strategy • Assess impact of electrical noise on detector • Measure fusion rate profile in MHD-quiescent conditions with both proton detector & neutron camera to assess whether former can provide absolutely calibrated profile • Scan in Ip to determine effects on proton & neutron yields of fishbones & sawteeth • For each Ip repeat pulse several times to scan in proton probe head rotation angle & neutron camera tangency radius  finely-resolved radial profiles of fusion rate • Study time-evolution of fusion proton flux during single fishbone burst & compare with HAGIS/LOCUST-GPU simulations • Measure proton/neutron fluxes following beam blips to study beam ion slowing-down Ken McClements: MAST Team Meeting

8. M9-FPP-002: suppression of chirping modes • Aim • Develop reproducible scenario in which Alfvénic chirping modes (excited by beam ions) can be suppressed by 2nd beam • Strategy • Change 2nd beam primary energy E2 such that E2/2 or E2/3 matches Alfvén energy EA (1st beam energy E1 held fixed) – Alfvén modes strongly damped due to large negative f/E at resonance (1 session) • If above is successful, for fixed E1 & E2 scan to match E1,2/3 &/or E1,2/2 with EA (1 session) • Swap beams & repeat - beams partitioned differently between primary, secondary & tertiary energies (1 session) • Specific requirements • Need to vary primary energy of 1 beam Ken McClements: MAST Team Meeting

9. M9-FPP-003: CAEs/hybrid modes in H:D • Aim • Study spectrum of compressional Alfvén (CAEs) & ion-ion hybrid eigenmodes in plasmas containing 2 dominant ion species with unequal cyclotron frequencies (H & D in MAST; D & T in reactor) • Strategy • Start from pure D plasma & establish reference scenario with CAE activity at frequencies   D(0) (1 session) • Gas puff H to increase concentration in steps up to 100%, using neutron flux to monitor H = nH /(nH + nD); 1 beam only required, so beam-beam rate very low • Detect modes in ion-ion hybrid frequency range D    H (2 sessions) • Specific requirements • Experiment will need to be scheduled at end of campaign • H gas puffing • Low Bt (~0.34T)to ensure that H /2 lies within measurable range (5 MHz) allowed by sampling rate of OMAHA coils Ken McClements: MAST Team Meeting

10. M9-FPP-004: TAE antenna Constant frequency sweeps in n=1 • Aim • demonstrate that externally-excited TAEs can be detected & damping measured • Strategy • Strong signal detected using OMAHA coils at driving frequency in M8: further investigations will be carried out to determine whether signals of this type are of plasma origin • Sweep antenna frequency; width of frequency response yields damping rate • Scan in density ne, Bt &/or Ip to determine whether excited frequencies have expected TAE scaling, i.e. • If successful, repeat for range of toroidal mode numbers • Specific requirements • Commissioning upgraded system (new prototype power supplies) can be parasitic in start-up due to flexibility through the linkboard (no beams required) • Limiter plasmas preferred (detection of externally-excited TAEs found to be much easier in limiter configuration in JET) + single beam required for initial shots OMAHA coil signal Strong signal only recorded on OMAHA coils at TAE antenna driving frequency  = (108.01.0)kHz  = (118.00.5)kHz  = (98.00.5)kHz Ken McClements: MAST Team Meeting

11. M9-FPP-005: Fast ion redistribution • Aim • measure neutron profile resulting from fast ion redistribution & losses during fishbones & long lived modes (LLMs) • Strategy • FIDA & neutron measurements in M8 suggest that LLMs have locally strong effect on fast ion redistribution (core diffusivity~ 6 m2s-1), but more shots needed to get neutron camera profiles with simultaneously good radial resolution & good statistics • Scan plasma beta by varying Bt between shots to determine beta dependence of fishbone excitation & effect of this on fast ion redistribution • Specific requirements • FIDA & neutron camera • Part of this experiment will be parasitic on IOS-002 (Determine parameter space to avoid fast ion redistribution) Ken McClements: MAST Team Meeting

12. What has been omitted? • “Three-wave coupling between TAEs and n=1 mode”, proposed by M Podestà (PPPL), has been omitted from programme • Main reason: low likelihood of success (would have required hardware modification to TAE antenna to excite frequencies in 10-25 kHz range) Ken McClements: MAST Team Meeting