A. Kanareykin, Euclid Techlabs LLC, ATF Users Meeting 2012 Beam manipulation by THz self-wakefield at ATF (I) A.Kanareykin Euclid TechLabs LLC, Gaithersburg, MD ATF Users Meeting BNL, April 26-27, 2012

A. Kanareykin, Euclid Techlabs LLC, ATF Users Meeting Outline Proposed experiments Chirp Compensation Energy Modulation Transformer Ratio Enhancement What technology, software and material we’ve got to accomplish it ? Beam manipulation Electromagnetic simulations software Diamond based structures Nonlinear materials

A. Kanareykin, Euclid Techlabs LLC, ATF Users Meeting 2012 We are pursuing three experiments at the ATF, two related to beam manipulation by its self-wakefield and one – a direct wakefield acceleration:  A demonstration of a tunable beam energy chirp compensator.  The conversion of self-wake energy modulation into a THz bunchtrain.  A demonstration of enhanced transformer ratio by a shaped beam. Proposal

A. Kanareykin, Euclid Techlabs LLC, ATF Users Meeting 2012 Motivation Light source is an intrinsic requirement for current and future scientific research. Particularly, ultrashort x-ray pulses are a powerful tool for addressing grand challenges in science. One particular obstacle limiting construction of FEL light source facilities is the cost, particularly, linacs to provide high energy, high brightness beam. wanted: gradient >100MV/m, peak current >1kA, rep~1MHz, E~ a few GeV, etc. In the past few years, the field of high gradient acceleration, aimed at the future high energy linear collider, achieved many impressive results. e.g. GV/m level in THz; 100 MV/m in MW demonstrated in DWA structures; wanted E ~ MV/m, R>10.

A. Kanareykin, Euclid Techlabs LLC, ATF Users Meeting Currently Available Beam Resources for Euclid’s Experiments. FacilityMain parameters ANL/AWA 15MeV/ 75 MeV,  z = 1-2 mm, Q = nC, yielding ~ MV/m at GHz or ~GW beam power; TBA; BNL/ATF 60 MeV, tunable  z = 100 um-1.5mm,  r ~100um, nC, THz SLAC/FACET 23 GeV,  z = um,  r ~ 10 um, Q = 1-3 nC, 0,5- 1,0 THz frequency, 1-10 GV/m

A. Kanareykin, Euclid Techlabs LLC, ATF Users Meeting Euclid THz DWA structures at FACET e-e- Kraken Chamber by UCLA/SLAC Through Collaboration E201 (UCLA/SLAC/Euclid) 23GeV, 3nC,  r~10µm,  z~30µm Euclid Structure DimensionsExp. Grad. (3nC,  z~30µm) Quartz tube 1 400µm ID 550µm OD 1.6GV/m ~0.6THz Quartz tube 2 300µm ID 415µm OD 2.5GV/m ~0.63THz Alumina tube 508µm ID 790µm OD 0.9GV/m multimode Sapphire tube 790µm ID 1090µm OD 0.5GV/m multimode Diamond slab 150µm gap 90µm thickness 1GV/m multimode Diamond tube 105µm ID 165µm OD 8.8GV/m ~1THz

A. Kanareykin, Euclid Techlabs LLC, ATF Users Meeting 2012 Chirp compensation: The free electron laser (FEL) is considered to be the main candidate for a short wavelength (UV to X-ray), short pulse (femto- to attosecond) light source. Demands: (1) high repetition rate (~MHz) (2) high peak current (a few kA); (3) low emittance (sub-micron emittance). At the output of the last compressor - a small energy chirp. It is required that this relatively small energy spread be compensated using a specially designed device. This compensation can be realized by a simple wakefield device. In 2011 we demonstrated energy compensation at the ATF [Antipov et al, PRL, 2012]. We now propose to test and demonstrate the first tunable energy chirp compensating system. Chirp Compensation

A. Kanareykin, Euclid Techlabs LLC, ATF Users Meeting 2012 Energy modulation conversion into a THz bunchtrain: a follow up experiment to our 2011 experimental program [Antipov et al, PRL 2012]. We observed energy modulation produced by a self-wake on an originally chirper beam. This energy modulation can be transferred into density modulation via a chicane. We propose to perform this transformation at the ATF. This process of self-wake energy modulation and a follow up conversion into a THz bunchtrain is the basis of an inexpensive, table top, high power THz source. Energy modulation

A. Kanareykin, Euclid Techlabs LLC, ATF Users Meeting 2012 The transformer ratio: a high transformer ratio leads to a higher overall efficiency. The experiment will be the first demonstration of enhanced transformer ratio from a triangular shaped beam. This experiment is similar to the diamond structure wakefield mapping accomplished at the ATF in 2011 [Antipov et al, APL 2012]. We propose to use a motorized mask to produce a drive beam followed by a witness beam at variable distance. Transformer Ratio Enhancement

A. Kanareykin, Euclid Techlabs LLC, ATF Users Meeting 2012 Ramped Bunch Reference: Bane et. al., IEEE Trans. Nucl. Sci. NS-32, 3524 (1985) Ramped Bunch Train Reference: Schutt et. al., Nor Ambred, Armenia, (1989) z d d W - W + d  (z) Measured Enhancement factor of R 2 /R 1 =1.31 Inferred R 2 =2.3 R 2 =3.4 (2007) Transformer Ratio Enhancement Using a Bunchtrain

A. Kanareykin, Euclid Techlabs LLC, ATF Users Meeting 2012 Key Technology --- bunch shaping to enhance transformer ratio Triangular bunch Double triangular bunch TR~10 TR~17 (STAB, 2012)

A. Kanareykin, Euclid Techlabs LLC, ATF Users Meeting 2012 Simplified sketch of the EEX beamline. Bunch charge30 nC Beam energy30 MeV Beam size (RMS x\y)0.7 cm\0.3 cm Bunch length (RMS)1.7 mm Energy divergence (RMS)95 keV EEX line dipole length0.5 m Bending angle45º Deflect cavity voltage3.6 MV (peak) Drift space (between 2 dipoles)0.3 m An example ---using EEX technique Refer to Sergey’s

A. Kanareykin, Euclid Techlabs LLC, ATF Users Meeting 2012 Software Developed for DLA Waveguide’09 Multibunch’09 Rectangular’11 BBU’300 Energy Modulation’11

A. Kanareykin, Euclid Techlabs LLC, ATF Users Meeting 2012 Dielectrics Tested as DLA Loading THz experiments at ATF

A. Kanareykin, Euclid Techlabs LLC, ATF Users Meeting 2012 CVD DIAMOND PROPERTIES: - DC BREAKDOWN THRESHOLD OF ~ 2 GV/m - LOSS FACTOR DOWN TO 5-9 x10 -5 AT GHz - HIGHEST THERMAL CONDUCTIVITY - MULTIPACTING CAN BE SUPPRESSED and CVD DEPOSITION NOW CAN BE USED TO FORM CYLINDRICAL WAVEGUIDES Motivation for CVD Diamond for DLA Element Six

A. Kanareykin, Euclid Techlabs LLC, ATF Users Meeting GHz Diamond Based DLA Structure CVD diamond tube fabrication

A. Kanareykin, Euclid Techlabs LLC, ATF Users Meeting 2012 THz Diamond Tubes (Bristol University, UK) Scanning electron microscope images of a THz diamond microstructure produced using the hot wire deposition technique. THz diamond structure: ID = 100 μm, thickness 70 μm, 1 cm long Single crystal diamond

A. Kanareykin, Euclid Techlabs LLC, ATF Users Meeting Experimental Report on A Diamond Based Wakefield Structures (DoE SBIR ext. Phase II project, 2012)

A. Kanareykin, Euclid Techlabs LLC, ATF Users Meeting 2012 Wakefield Mapping of a Diamond Slab Structure at BNL/ ATF 0.25 THz 1 st wakefield mapping experiment in THz regime (June 2011). 1 st wakefield acceleration observed in THz regime. S. Antipov, et al, App. Phy. Lett. March 2012.

A. Kanareykin, Euclid Techlabs LLC, ATF Users Meeting 2012 High Grad. Breakdown Study of A Diamond Slab ANL/ AWA Bunch length2~2.5 mm Beam gap4.0 mm D thickness1.2 mm width8 mm length5.0 mm 50MV/m per 50 nC beam Our goal is to perform first WF experiment with Diamond-based DLA, test for breakdown Structure is short, TM 110 – based Wake is a single mode at ~ 26 GHz Q = 2800 (  decay time  ~35ns) *AWA facility can generate up to 100nC beam with σ z = 2.5 mm (14 MeV)

A. Kanareykin, Euclid Techlabs LLC, ATF Users Meeting 2012 Field Enhancement in the scratch Avoiding hot spots on diamond holder beam Diamonds (E6)...scratched Field is ~5 times higher beam 50nC  250 MV/m

A. Kanareykin, Euclid Techlabs LLC, ATF Users Meeting 2012 Diamond groove SEM image SEM: Z. Yusof (AWA) Cut: J. Butler (NRL) Image: “BEFORE”

A. Kanareykin, Euclid Techlabs LLC, ATF Users Meeting 2012 High Gradient Beam Test afterbefore 72nC (σ z =2.5mm) went through which is eqv. to ~ 0.3 GV/m gradient on axis for decay time τ ~ 35ns. Preliminary examination shows No evidence of breakdowns during the beam test. More examinations or additional test will be carried out. SEM: Sergey Antipov, Euclid and Sergey Baryshev, MSD ANL

A. Kanareykin, Euclid Techlabs LLC, ATF Users Meeting Nonlinear Ferroelectric Materials for DLA Based Accelerator Structure (DoE SBIR. Phase II project, completed)

A. Kanareykin, Euclid Techlabs LLC, ATF Users Meeting 2012 Temperature Tuning Effects in Dielectric- Based Accelerating Structure ε(E) for ferroelectric dielectric composite Temperature tuning 14 MHz/ 0 K

A. Kanareykin, Euclid Techlabs LLC, ATF Users Meeting 2012 Relative permittivity as a function of electric field strength for a composite ferroelectric dielectric Lineout of the electric field on axis for different beam intensities. Red: Q=0.03 nC; Blue: Q=0.30 nC; Green: Q=3 nC (cf. Fig.21). For ease of comparison the data is scaled to Q=3.0 nC. Nonlinear Effects at FACET DLA DoE SBIR. Phase I, to be submitted 2012

A. Kanareykin, Euclid Techlabs LLC, ATF Users Meeting Euclid DLA Experiments planned in 2012 THz DWA at FACET /SLAC (April 2012) THz DWA test at ATF/BNL (fall 2012)  Chirped electron bunch energy compensation for an x-ray light source, Phase II submitted, BES  Enhanced transformer ratio using a double triangular beam generated with the E-EX technique, Phase II submitted, HEP