SPARCLAB Source For Plasma Accelerators and Radiation Compton with Laser And Beam
EMITTANCE X X X X X X X X Introduction to SPARC_LAB 2
BRIGHTNESS (electrons) B n 2I nx ny A m 2 rad 2 The current can be increased compressing longitudinally the bunch The emittance can be decreased with laser pulse shaping, transverse uniformity, good working point, better alignment etc. Introduction to SPARC_LAB 3
SPARCLAB R&D on advanced beam dynamics R&D on FEL radiation Developing a THz source Developing a Thomson source R&D on plasma acceleration Thomson source THz source Plasma acceleration Plasma acceleration 300 TW, < 25 fs Ti:Sa laser THz source FEL source Photoinjector Introduction to SPARC_LAB 4
Papers In the last 6 years more than 50 papers published in 14 different peer-reviewed journals Among the others 8 in Physical Review Letters 5 in Physical Review Accelerators and Beam 3 In Applied Physics Letters 2 In New Journal of Physics 1 Nature Communication 1 Scientific Report 1 Phys. Med. Biol Introduction to SPARC_LAB 5
EUROPEAN PLASMA RESEARCH ACCELERATOR WITH EXCELLENCE IN APPLICATIONS This project has received funding from the European Union s Horizon 2020 research and innovation programme under grant agreement No 653782. Introduction to SPARC_LAB 6
Consortium 16 Participants 22 Associated Partners (as of October 2016) Introduction to SPARC_LAB 7
EuPRAXIA Research Infrastructure PLASMA ACCELERATOR HEP & OTHER USER AREA FEL / RADIATION SOURCE USER AREA Introduction to SPARC_LAB 8
LASER SYSTEM SPARC Laser system (Ti:Sa) 0.5 TW Diagnostic and Matching Seeding Introduction to SPARC_LAB 9
S-BAND GUN Laser Port Undulators r = 500 nm 15 m Diagnostic RF power and Matching Cathode Long Solenoids S-band Gun Seeding Gun Solenoid THz Source UCLA/BNL design Solenoid ~3 kg Input Power 14 MW Max Acc. Field @ cathode ~130 MV/m Introduction to SPARC_LAB 10
S-BAND LINAC 180 MeV S-band linac 12 m Undulators r = 500 nm Focusing solenoid 15 m Long Solenoids Beam axis Seeding THz Source SLAC constant gradient design Solenoid ~300 G Accelerating field ~20 MV/m Introduction to SPARC_LAB 11
DIAGNOSTICS AND MATCHING Diagnostics and Matching SCREENS DIPOLE Quadrupoles Seeding THz Source RF DEFLECTOR Introduction to SPARC_LAB 12
PHASE SPACE MANIPULATION Gun focusing field (~3kG) Emittance Bunches current, length Accelerating field ENERGY SEPARATION Inj. phase TIME SEPARATION Gun inj. phase and space charge Bunches distance at the linac entrance TW focusing field (~300G) Emittance Bunches current, length S2 phase ENERGY SPREAD Gun exit energy Beam brightness Compression phase stability Bunch separation stability Introduction to SPARC_LAB 13
UNDULATORS 180 MeV S-band linac 12 m Undulators r = 500 nm 15 m Long Solenoids S-band Gun Beam Seeding Variable gap undulator Halbach type Introduction to SPARC_LAB 14
Comb Beam generation Introduction to SPARC_LAB 15
4 bunches COMB beam Measurement Simulation Introduction to SPARC_LAB 16
5 bunches Time Space Introduction to SPARC_LAB 17
2 COLORS FEL 1 two bunches with a two level energy distribution and time overlap 2 1 2 18 nm produce two wavelength SASE FEL Introduction to SPARC_LAB 18
22 fs pulse Beam A B 22.8 nm 23.8 nm frog 17.9 nm 18.6 nm Spectral domain Time domain Beam A B t 112 fs 91 fs t 26.7 fs 22.5 fs Introduction to SPARC_LAB 19
SASE vs Seedings Introduction to SPARC_LAB 20
THz GAP THz radiation is non ionizing and highly penetrating in a large variety of insulating materials THz part of the spectrum is energetically equivalent to many important physical, chemical and biological processes including superconducting gaps and protein dynamical processes Introduction to SPARC_LAB 21
Scientific motivations THz radiation as Coherent Radiation from sub-ps high brightness beams intense source because of high THz field Ultra-fast and non-linear phenomena Potential of conditioning and controlling matter Probing feature of THz radiation THz pump THz probe spectroscopy Imaging in biological applications Introduction to SPARC_LAB 22
BIO applications THz radiation is absorbed by polar liquids (such as water), thus it might be used to detect differences in body tissue density Using THz spectroscopy, diseased human tissues like tumors would image differently than do normal tissues and, since this radiation is non ionizing, it also is a safer medical and dental imaging alternative Region with tumor appears more transmissive since it originally contained more fluid Introduction to SPARC_LAB 23 23
The SPARC_LAB THz beam lines CTR and CDR sources CTR source Coherent Radiation from an aluminum-coated silicon screen (Coherent Transition Radiation, CTR) and from a rectangular aperture in the metallic screen (Coherent Diffraction Radiation, CDR). Introduction to SPARC_LAB 24
Broad-band THz radiation: Measurements Electron beam parameters Energy (MeV) 100 Intensity (arb. units) Charge (pc) 260 RMS bunch length (fs) 260 Appl. Phys. Lett. 102, 094101 (2013) Introduction to SPARC_LAB 25
Narrow-band THz radiation Electron beam parameters Measured Longitudinal Phase Space (LPS) Energy (MeV) 110 Charge/bunch (pc) 50 RMS single bunch length (fs) 200 Autocorrelation measurement of CTR with a Martin-Puplett interferometer CTR Energy ( J/THz) 0.7 0.6 0.5 0.4 0.3 0.2 0.1 0.0 Retrieved CTR energy spectrum J Rev. Sci. Instrum. 84, 022703 (2013) 0.0 0.5 1.0 1.5 2.0 Frequency (THz) Introduction to SPARC_LAB 26
Detection apparatus Introduction to SPARC_LAB 27
Nonlinear THz response of Bi 2 Se 3 Transmission E field intensity MV/cm A Topological Insulator is an exotic electronic material showing an insulating bulk and intrinsic metallic surfaces. The metallic surfaces are characterized by a gas of Dirac electrons, i.e. having a relativistic dispersion: E(k)=v F kwhere v F is the Fermi velocity. In this experiment we observe a nonlinear optical behavior of Dirac electrons characterized by THz harmonic generation Nature Communications 7, 11421 (2016) Introduction to SPARC_LAB 28
Thomson back-scattering source Introduction to SPARC_LAB 29
A good source of information Introduction to SPARC_LAB 30
BANDWIDTH CONTROL dn/de 0,004-5 0,003 0 5 10 15 E(MeV) 0 10 20 E(MeV) E(MeV) E(MeV) E (kev) 20 The energy angle correlation permits the control of bandwidth and divergence 0,002 By introducing irides or collimators one can diminish the bandwidth, by selecting only the photons close to the axis Y 0,001 0,000-0,001-0,002-0,003-0,004-0,004-0,003-0,002-0,001 0,000 0,001 0,002 0,003 0,004 A. Cianchi X Introduction to SPARC_LAB 31
MAMMOGRAPHY Photons of energies other than the one maximizing dose efficiency would lead to lower contrast (in case of high energy) or higher dose to the patient(provided by the energies lower than the optimal one) The energy spectrum of conventional mammographic X-ray tube systems is polychromatic, and even after k- edge filtration, it shows a significant number of photons in the whole range between about 10 kev and the maximum photon energy Compton or Thomson scattering can provide quasi-monochromatic, high-flux X-ray beams Introduction to SPARC_LAB 32
Applications Worldwide Radiography done at BNL, Brookeven Radiographies done at CLS, Palo Alto Absorption Dark field Phase contrast Introduction to SPARC_LAB 33
Plasma accelerators In conventional Radio-Frequency (RF) cavities, the accelerating gradients are limited to about 50 MV/m (dielectric breakdown of cavities). Ionized plasmas: can sustain electron plasma waves with electric fields 3 orders of magnitude higher, and the accelerating field strength is tunable by adjusting the plasma density. Introduction to SPARC_LAB 34
PLASMA ACCELERATION In conventional Radio-Frequency (RF) cavities, the accelerating gradients are limited to about 50 MV/m (dielectric breakdown of cavities). Ionized plasmas: can sustain electron plasma waves with electric fields 3 orders of magnitude higher, and the accelerating field strength is tunable by adjusting the plasma density. Two Plasma-based accelerator techniques are possible: Self-injection: plasma and particle created by TW-laser pulse; External-injection: particles injected externally; driven by laser-pulses (LWFA) driven by particle-bunches (PWFA) Accelerating gradients of GV/m reached! 35
Plasma lens Introduction to SPARC_LAB 36
PWFA 37
Plasma discharge Introduction to SPARC_LAB 38
FLAME Introduction to SPARC_LAB 39
Self-injection experiments Source optimization and parametric study of the laser and plasma parameters is undergoing. 174 MeV 57 MeV 236 MeV 81 MeV So for example by scanning the plasma density, electron energy has been varied from 50 MeV, to 175 MeV and up to 300 MeV. Gradient achieved 200 GV/m!! Also by tuning plasma density, energy spread has been reduced from 100% to 20%. Introduction to SPARC_LAB 40
Interferometry Refractive index is determined from the experimentally measured values of the optical difference of the path. LASER (400nm) M BS PLASMA BS M CCD PLASMA REFRACTIVE INDEX Free e density Critical density The refractive index variation causes a dephasing that is directly related to the electron density MachZender interferometer to measure the plasma density. Using this diagnostic we have shot to shot measurement of the density and the total accelerating length. Introduction to SPARC_LAB 41
Target Normal Sheath Acceleration Proton and ions are too slow to catch the wave: only indirect acceleration via electrons Laser (10 19 W/cm 2 ) creates a blow off plasma on front surface Hot electrons create electric field by space charge It accelerates protons Introduction to SPARC_LAB 42