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Proposal for AWAKE

Proposal for AWAKE. University of Oslo, Norway. Erik Adli Veronika K.B. Olsen Department of Physics, University of Oslo, Norway AWAKE collaboration meeting CERN, CH, Dec 5, 2013. Overview. Current Oslo activities Proposal for AWAKE. Oslo Accelerator Group.

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Proposal for AWAKE

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  1. Proposal for AWAKE University of Oslo, Norway Erik Adli Veronika K.B. Olsen Department of Physics, University of Oslo, Norway AWAKE collaboration meeting CERN, CH, Dec 5, 2013

  2. Overview Current Oslo activities Proposal for AWAKE

  3. Oslo Accelerator Group The accelerator activities at the University of Oslo, Norway, is within the High Energy Physics Group at the Department of Physics. The group currently has 4 professors, 1 professor II, 1. assoc. prof, 7 researchers/post. docs. and about 10 Ph.D. students – out of which 5 do accelerator physics. The HEP-group has strong links with the theory group, the computational physics group and electronics/instrumentation workshops at the Department of Physics. Current Univ. of Oslo accelerator personnel (AWAKE relevance) : • Erik Adli, Assoc. Prof, lead of accelerator activities and currently Visiting Physicist at Stanford Univ./SLAC • Veronica K.B. Olsen, PhD student for work on AWAKE (started fall 2013) • Kyrre N. Sjøbæk, PhD student on CLIC (3rd year) • Reidar L. Lillestøl, PhD student on CLIC (3rd year) • Henrik Bjerke, MSc student on PWFA at FACET • + 3 more CERN-funded PhD students on other CERN accelerator projects • Prof. Steinar Stapnes (10%; on-leave as CERN linear collider study leader) Future prospect: We have continuing applications for more funding to linear collider activities + considering including applications for AWAKE in future

  4. Relevant Oslo activities Our AWAKE proposal is related to study of the performance of an AWAKE witness beam for the “2nd phase”. More details in second part of the presentation. Current Oslo activities with relevance to AWAKE will be presented first. • Linear collider studies (at CERN/CLIC/CTF3) • Plasma wakefield acceleration experimental studies (at SLAC/FACET) • PWFA linear collider design

  5. Current activities: CLIC beam dynamics • Oslo: CLIC collaboration lead on drive beam energy extraction and deceleration. Theory, simulations and experiments • Beam dynamics and diagnostics for large energy spread beams. CLIC 100 A drive beam: provide 12 GHz rf power to the CLIC main linac. The drive beam is decelerated to 10% energy • Study of Ultra-low emittance preservation of linear collider main beams. Simulations + experiments at FACET • CLIC requires preservation of 10 nm normalized emittances over 20 km of main linacs. Advanced emittance preservation schemes currently being tested at FACET • E. Adli et al., Phys. Rev. ST Accel. Beams, 14, 081001 (2011) • A. Latina et al., submitted to Phys. Rev. ST Accel. Beam

  6. Current activities: CLIC Test Facility 3 Experimental verification of the CLIC drive beam scheme (“CTF3 Test Beam Line”) and participation in the CLIC two-beam acceleration demonstrations : Two-beam acceleration test stand; > 100 MV/m gradient demonstrated using two-beam acceleration. 12 GHz power extraction structure • M. Olvegaard et al., Phys. Rev. ST Accel. Beams, 16, 082802 (2013) • R. Lillestol et al., submitted to Phys. Rev. ST Accel. Beam

  7. Current activities: PWFA experiments at FACET Oslo: member of the e- PWFA experiments currently going on at FACET.

  8. FACET experiments vs AWAKE FACET: e- driven PWFA mainly in the blow-out regime (2012 -> ) : AWAKE: proton driven PWFA in self-modulated regime (2016 -> ) : ~kJ proton bunches. sz >> lp, low peak current (~100A), rely on S-M for large fields. FACET : ~J e- bunches. sz ~ lp, high peak current (~10kA), blow-out

  9. The FACET E200 experimental set-up 10 TW Ti:Sa laser for plasma pre-ionization. Experimental setup : some similarities to AWAKE. • W. An et al., Phys. Rev. ST Accel. Beams, 16, 101301 (2013) • N. Vafaei-Najafabadi et al., Accepted for publication in Phys.Rev.Lett.

  10. June 2013: first witness bunch acceleration results Laser off: Laser on (subsequent shot): Unpublished Acceleration of witness bunch by ~2 GeV in 30 cm of plasma

  11. Current activities: PWFA based linear collider PWFA-LC: re-design with respect to Seryi et al. 2009 design. Prepared for “Snowmass 2013” : A detailed LC design of a PD-PWFA, based on experience from CLIC and ILC, assuming plasma “works”. * E. Adli et al., presented at IPAC’13, http://arxiv.org/abs/1308.1145 * J.P.Delahaye et al., White Paper input to US Snowmass Process 2013

  12. Gradient, efficiency, emittance, energy spread Key performance parameters for PWFA witness bunch acceleration in applications (numbers for FACET-like scenarios) : Gradient (~>10 GV/m) Efficiency (~>50%) Emittance preservation Energy spread (~1%) Not fully answered what performance we can achieve in the self-modulated regime, or in particular in AWAKE. Personal view : Status: Established Current research Challenging

  13. Overview Current Oslo activities Proposal for AWAKE

  14. Awake proposal summary I We propose a full time PhD project on AWAKE, with main topic “parameter optimization and performance evaluation for a witness bunchfor an on-axis e- acceleration experiment”. Attempt to answer : how good e- acceleration can we possibly achieve in the self-modulated regime? Input to e- acceleration experiment designs. Resources: • Veronica K.B. Olsen, Oslo PhD student, 4 years (Aug 2013-Aug 2017), Full time study on AWAKE (25% teaching duties during the 4 years) • Erik Adli, Oslo supervisor, Supervision on the work. Studies of LC applications. • Additional resources is planned to be sought in future funding applications, but nothing can be promised at the current stage. Work flow: start from studying plasma physics, and extract ideal e- source parameters ?

  15. Awake proposal summary II Work planned: • The candidate will study the optimal parameters for a e- witness bunch, including injection considerations and plasma source considerations, primarily by simulations [more details on next slides]. Results from study input to acceleration experiment beam line design ( “phase 2”). • The candidate will also participate in the commissioning of the experimental hardware and the first proton experiments, assuming the first experiments are not delayed by more than one year with respect to the current schedule. Several shorter, and one extended stay at CERN (~0.5-1 year, probably in 2016) is foreseen. • PWFA experiments for pre-studies for AWAKE will take place at the FACET test-facility in 2013 and 2014.   The candidate will also participate in the experimental pre-studies in order to gain an understanding of PWFA experiments. Several stays at SLAC is foreseen. Main tool: • Use of the PWFA PIC code Osiris. We have recently started a collaboration with IST Portugal for the use of Osiris (at Oslo) for AWAKE. MoU between IST and Oslo. Will build on IST proton simulation work, enhance with e- witness bunch. Current partners: • IST (for Osiris Simulations/Theory), MPP (co-supervision of the thesis work)

  16. Simulation plans: I I) Optimization of witness bunch parameters in a self-modulation regime:Overall, it is important to develop a good understanding on the dependencies of witness bunch parameters (witness bunch charge, length, transverse size, etc.) on the performance. Key topics are how to achieve the best emittance preservation in the quasi-linear wakes of the self-modulation regime, as well as the how to achieve narrow final energy spread and good efficiency, typically by beam loading of the wake field (c.f. Patric’s talk yesterday). Beam loading in linear regime and blow-out regime has previously been studied in detail [e.g. Tzoufras, Katsouleas]. We need to investigate in details for the self-modulated regime. Beam-loading in linear regime and non-linear regime (M. Tzoufras et al. Phys. Rev. Lett. 2008 )

  17. Simulation plans: II II) Realistic modeling of plasma source/boundaries: The e- witness bunch will be injected into the plasma moving gradually from vacuum to a fully formed plasma. Related effects will occur at the exit of the plasma into vacuum. The plasma source may not provide uniform density. In order to achieve optimal witness bunch performance, the influence of plasma source density variationsneeds to be studied.  If the density is low in the boundaries there may be defocusing and energy loss, and understanding the effect of those on the propagation (risk of beam loss) and emittance is important.  The details of the boundary will depend on the type of plasma source to be used, and we will interact with source developers to understand details. . Example of matching into an ideal plasma density ramp, with profile : as measured from the heat-pipe oven used at SLAC/FACET (for this simple case the the virtual waist position and width can be calculated analytically).

  18. Simulation plans: III III) Transverse tolerances : • Injection offset/angle of the e- witness bunch with respect to the focusing channel will lead to betatron oscillations, hosing, betatron radiation and in general additional emittance dilution.  The physics of the hosing instability in plasma wakefields is non-trivial and an item of intense research in the field [9].  A study of these effects will lead to transverse tolerances on the injection mechanism into the plasma, which should be input directly into the e- experimental beam line design. Note: This part will require 3D simulations, very computationally intensive. Example: study of witness bunch hosing in the blow-out regime : witness bunch is offset with respect to drive bunch with offset Dx/sx~ 1 (for illustration): severe impact on witness bunch emittance. Similar studies must be performed also for e- injection into the AWAKE proton wake.

  19. Simulation plans: IV IV) e+ witness bunches.  Due to the opposite charge, e+ witness bunches may behave very differently from e- bunches in the self-modulated regime.  Can similar performance as for e- bunches be achieved for e+ bunches?  We consider this topic as an option, that will be addressed only if there is sufficient time and interest in the topic towards the latter half of the PhD. Linear regime: e- and e+ behave similarly Blow-out regime: e- and e+ very different behavior (very challenging to get good efficiency and emittance preservation for e+ witness bunch acceleration) Of interest to study also for the AWAKE self-modulated regime.

  20. Rough timeline 2014 : * Get up to speed on Osiris simulations (target: by jan/feb 2014) * Perform an initial assessment of the parameters of an optimal AWAKE witness bunch parameters (2014) * Participate in preparatory PWFA experiments at FACET  (spring 2014) 2015 : * Detailed studies of witness bunch injection offset tolerances * Detailed study of the impact of plasma source boundaries and/or imperfections for witness bunch performance * Interaction with / input to e- accelerator experiment design groups 2016: * Participate in the experimental preparation, commissioning and first runs for the AWAKE experiment at CERN 2017 (PhD grant ending Aug, 2017) : * Participation in the AWAKE experiment at CERN * Write-up and completion of Thesis

  21. Summary • The University of Oslo proposes to participate in the AWAKE collaboration, with focus on studying “parameter optimization for a witness bunch for an on-axis e- acceleration experiment”, and providing input for accelerator experiment beam line requirements • Will brings experience from witness bunch simulation and experiments in the PWFA blow-out regime + linear collider requirements • We propose to also participate in experiment commissioning • One PhD student full time • Being part of the in collaboration would open up possibilities to apply for further funding

  22. Extra

  23. Current activities: e- self-modulation studies We participate in the SLAC/FACET experiment on self-modulation of a long e- bunch in a pre-ionized plasma (sz ~ 1 mm ~ 5-10 lp). “Pre-experiment” for AWAKE (PI: Muggli). First experimental run [without plasma] in November 2013. Purpose: test of THz pyro detectors (energy measurements)dependence of transverse bunch size. Experiments with plasma expected spring 2014. pyro 1 “Beta knob” pyro 2 Preliminary results show clear correlation between pyro amplitude and beam beta functions. Important in order to be able to measure self-modulation with OTR

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