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

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


2

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


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


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 ~200- 300 MV/m, R>10.


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Currently Available Beam Resources for Euclid’s Experiments.

Facility Main parameters

ANL/AWA 15MeV/ 75 MeV, z = 1-2 mm, Q = 10-100 nC, yielding ~ 100-300 MV/m at 10-30 GHz or ~GW beam power; TBA;

BNL/ATF 60 MeV, tunable z = 100 um-1.5mm, r~100um, 0.3-0.5 nC, 0.3-0.8 THz

SLAC/FACET 23 GeV, z = 20-30 um, r ~ 10 um , Q = 1-3 nC, 0,5-1,0 THz frequency, 1-10 GV/m


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Euclid THz DWA structures at FACET

e-

Kraken Chamber by UCLA/SLAC

Through Collaboration E201 (UCLA/SLAC/Euclid)

23GeV, 3nC, r~10µm, z~30µm

Euclid Structure

Dimensions

Exp. 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


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


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


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

z

z

EwR

w E

(z)

z W -

W+


Ramped BunchReference: Bane et. al., IEEE Trans. Nucl. Sci. NS-32, 3524 (1985)

c

(z)W+

W-z

Ramped Bunch Train

Reference: Schutt et. al., Nor Ambred, Armenia, (1989)

zd d

W -

W+

d

(z)

Measured Enhancement

factor of R2/R1=1.31

Inferred R2=2.3

R2=3.4

(2007)

Transformer Ratio Enhancement Using a Bunchtrain


Key Technology --- bunch shaping to enhance transformer ratio

Triangular bunch

Double triangular bunch

TR~10

TR~17

(STAB, 2012)


Simplified sketch of the EEX beamline.

Bunch charge 30 nC

Beam energy 30 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 length 0.5 m

Bending angle 45º

Deflect cavity voltage 3.6 MV (peak)

Drift space (between 2 dipoles) 0.3 m

An example ---using EEX technique

Refer to Sergey’s


Software Developed for DLA

Waveguide’09

Multibunch’09

Rectangular’11

BBU’300

Energy Modulation’11

Distance behind the bunch, cm0

Wak

efie

ld ,

V/m

10,000,000,000

8,000,000,000

6,000,000,000

4,000,000,000

2,000,000,000

0

-2,000,000,000

-4,000,000,000

-6,000,000,000

-8,000,000,000

-10,000,000,000

Distance behind the bunch, cm

3210-1

Wak

efie

ld ,

MV

/m

1

0,8

0,6

0,4

0,2

0

-0,2

-0,4

-0,6


dielectric ε Tan δ

(10 GHz) Frequency

(GHz) Experiment, reference

Quartz 3.8 <1×10-4 11.4 High Gradient Standing Wave

Cordierite 4.7 <1.5×10-4

7.8

8.6

21

11.4/30

7.8 GHz TBA Power Extractor

High Gradient Standing Wave

21 GHz DL Power Extractor

Two Channel High Transformer Ratio

Diamond 5.7 <1×10-4 26-35 High Gradient Standing Wave

Forsterite 6.3 <2×10-4 11.4

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Traveling Wave DLA

26 GHz DL Power Extractor

Alumina 9.8 <1×10-4 11.4 Dual Layer DLA (outer layer)

MgTiO3 - Mg2TiO4

16 <1.2×10-4 13.6 Collinear High Transformer Ratio

MCT (Mg,Ca)TiO3

20 <2×10-4 7.8 Two Beam DLA Accelerator

BaTi4O9 37 <3×10-4 11.4 Dual Layer DLA (inner layer)

CaTiO3-LaAlO3 38.1 <5×10-4 1-30

(multimode) Multimode DLA bunch train generation

Dielectrics Tested as DLA Loading

THz experiments at ATF


CVD DIAMOND PROPERTIES:

- DC BREAKDOWN THRESHOLD OF ~ 2 GV/m

- LOSS FACTOR DOWN TO 5-9 x10-5 AT 30-140 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

Element Six


35 GHz Diamond Based DLA Structure

CVD diamond tube fabrication


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


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Experimental Report on A Diamond Based Wakefield Structures (DoE SBIR ext. Phase II project, 2012)


Wakefield Mapping of a Diamond Slab Structure at BNL/ ATF

0.25 THz

• 1st wakefield mapping experiment in THz regime (June 2011). • 1st wakefield acceleration observed in THz regime.• S. Antipov, et al, App. Phy. Lett. March 2012.


High Grad. Breakdown Study of A Diamond Slab Structure @ ANL/ AWA

Bunch length 2~2.5 mm

Beam gap 4.0 mm

D thickness 1.2 mm

width 8 mm

length 5.0 mm

50MV/m per 50 nC beamOur goal is to perform first WF experiment with Diamond-based DLA, test for breakdown

Structure is short, TM110 – based Wake is a single mode at ~ 26 GHzQ = 2800 (decay time ~35ns)

*AWA facility can generate up to 100nC beam with σz = 2.5 mm (14 MeV)


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


Diamond groove SEM image

SEM: Z. Yusof (AWA)

Cut: J. Butler (NRL)

Image: “BEFORE”


High Gradient Beam Test

afterbefore

72nC (σz=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


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Nonlinear Ferroelectric Materials for DLA Based Accelerator Structure (DoE SBIR. Phase II project, completed)


Temperature Tuning Effects in Dielectric-Based Accelerating Structure

forsterite BST(M)

ε(E) for ferroelectric dielectric composite

Temperature tuning 14 MHz/0K


Relative permittivity as a function of electric field strength for a composite ferroelectric dielectric

63 20 8 10

1 21

/.E( n ) n ( n )

x

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


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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

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

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