EuCARD-2 Enhanced European Coordination for Accelerator Research - PDF document

CERN-ACC-SLIDES-2014-0114 EuCARD-2 Enhanced European Coordination for Accelerator Research & Development Presentation Beam Propagation, effects and parameters of the accelerated beam Assmann, R (DESY) 27 November 2014 The EuCARD-2 Enhanced European Coordination for Accelerator Research & Development project is co-funded by the partners and the European Commission under Capacities 7th Framework Programme, Grant Agreement 312453. This work is part of EuCARD-2 Work Package 7: Novel Accelerators (EuroNNAc2) . The electronic version of this EuCARD-2 Publication is available via the EuCARD-2 web site <http://eucard2.web.cern.ch/> or on the CERN Document Server at the following URL: <http://cds.cern.ch/search?p=CERN-ACC-SLIDES-2014-0114> CERN-ACC-SLIDES-2014-0114

Beam Propagation effects and parameters of the accelerated beam R.W. Aßmann Leading Scientist DESY CERN, 27.11.2014

Content 1. Accelerators – From Conventional Techniques to Plasmas 2. The Linear Regime 3. The Non-Linear Regime 4. Tolerances Ralph Aßmann | CAS | 27.11.2014 | Page 2

Acceleration: Conventional and Advanced Surfer gain velocity and energy by riding the water wave! Charged particles gain energy by riding the electromagnetic wave! generate light pulses with very large transverse fields: couple fields to our particles! Ralph Aßmann | CAS | 27.11.2014 | Page 3

Governed by Maxwell � s Equations ∇ · E = ρ ∇ × E = − ∂ B ǫ 0 ∂t ∂ E ∇ · B = 0 ∇ × B = µ 0 J + ǫ 0 µ 0 ∂t = Electrical field intensity E = Magnetic flux density B = Total current density J = Total charge density ρ Very few acceleration issues = Permeability of free space µ 0 require quantum mechanics ǫ 0 = Permittivity of free space (e.g. spin polarization). Ralph Aßmann | CAS | 27.11.2014 | Page 4

Lorentz Force F = q ( E + v × B ) F = Charge q = Velocity v Longitudinal electrical Transverse magnetic field to accelerate a field to guide a particle particle Ralph Aßmann | CAS | 27.11.2014 | Page 5

RF Acceleration in Metallic Structures Courtesy N. Walker > ���������������������� ����������������� ��������������������� ����������������� �������������������� > �������� ������ �������� � �������� �������������� � � �������������� Courtesy Padamse, Tigner > ���������������������� ������������������� From Ising’s and Wideröe’s start to 21 st century ������������������ RF technology. ������������������ “Runzelröhre” ���������������������� Ralph Aßmann | CAS | 27.11.2014 | Page 6

High Gradient – High Frequency – Small Dimensions Band Frequency Gradient Cell length Comments Designator [GHz] [MV/m] [cm] L band 1 to 2 24 15 – 7.5 This band is used by super-conducting RF technology. The dimensions are large, accelerating gradients are lower and disturbing wakefields are weak. S band 2 to 4 21 7.5 – 3.8 Technology of the SLAC linac that was completed in 1966. This is still the technology behind many accelerators. Ralph Aßmann | CAS | 27.11.2014 | Page 7

High Gradient – High Frequency – Small Dimensions Band Frequency Gradient Cell length Comments Designator [GHz] [MV/m] [cm] S band 2 to 4 21 7.5 – 3.8 Technology of the SLAC linac that was completed in 1966. This is still the technology behind many accelerators. C band 4 to 8 35 3.8 – 1.9 Newer technology developed in Japan and used for the construction of the SACLA linac in Japan. Ralph Aßmann | CAS | 27.11.2014 | Page 8

High Gradient – High Frequency – Small Dimensions Band Frequency Gradient Cell length Comments Designator [GHz] [MV/m] [cm] C band 4 to 8 35 3.8 – 1.9 Newer technology developed in Japan and used for the construction of the SACLA linac in Japan. X band 8 to 12 70 – 100 1.9 – 1.3 Technology developed from the 1990’s onwards for linear collider designs, like NLC and CLIC. The cell length is up to a factor 10 shorter than in L band. Ralph Aßmann | CAS | 27.11.2014 | Page 9

High Gradient – High Frequency – Small Dimensions Band Frequency Gradient Cell length Comments Designator [GHz] [MV/m] [cm] X band 8 to 12 70 – 100 1.9 – 1.3 Technology developed from the 1990’s onwards for linear collider designs, like NLC and CLIC. The cell length is up to a factor 10 shorter than in L band. Ku band 12 to 18 n/a 1.3 – 0.8 K band 18 to 27 n/a 0.8 – 0.6 Ka band 27 to 40 70 0.6 – 0.4 Investigated for a possible CLIC linear collider technology at 30 GHz but abandoned after damage problems. V band 40 to 75 n/a 0.4 – 0.2 Ralph Aßmann | CAS | 27.11.2014 | Page 10 W band 75 to 110 > 1000 0.2 – 0.1 Advanced acceleration

High Gradient – High Frequency – Small Dimensions Band Frequency Gradient Cell length Comments Designator [GHz] [MV/m] [cm] L band 1 to 2 24 15 – 7.5 This band is used by super-conducting RF technology. The dimensions are large, accelerating gradients are lower and disturbing wakefields are weak. S band 2 to 4 21 7.5 – 3.8 Technology of the SLAC linac that was completed in 1966. This is still the technology behind many accelerators. C band 4 to 8 35 3.8 – 1.9 Newer technology developed in Japan and Plasma used for the construction of the SACLA acceleration in linac in Japan. X band 8 to 12 70 – 100 1.9 – 1.3 Technology developed from the 1990’s the > W band onwards for linear collider designs, like NLC and CLIC. The cell length is up to a factor 10 shorter than in L band. Ku band 12 to 18 n/a 1.3 – 0.8 K band 18 to 27 n/a 0.8 – 0.6 Ka band 27 to 40 70 0.6 – 0.4 Investigated for a possible CLIC linear collider technology at 30 GHz but abandoned after damage problems. V band 40 to 75 n/a 0.4 – 0.2 W band 75 to 110 > 1000 0.2 – 0.1 Advanced acceleration schemes with ultra Ralph Aßmann | CAS | 27.11.2014 | Page 11 high gradients and very short cell lengths.

Transverse to Longitudinal > Idea: Use a plasma to convert the transverse space charge force of a beam driver (or the electrical field of the laser) into a longitudinal electrical field in the plasma! Ralph Aßmann | CAS | 27.11.2014 | Page 12 R. Assmann 12

Reminder: Plasma-Acceleration (Internal Injection) Works the same way with an . But then usually lower plasma density. Ponderomotive force of laser is then replaced with space charge force of electrons on plasma electrons (repelling). Ralph Aßmann | CAS | 27.11.2014 | Page 13

Reminder: Plasma-Acceleration (Internal Injection) Ralph Aßmann | CAS | 27.11.2014 | Page 14

Reminder: Plasma-Acceleration (Internal Injection) - + - Ralph Aßmann | CAS | 27.11.2014 | Page 15

Reminder: Plasma-Acceleration (Internal Injection) Ralph Aßmann | CAS | 27.11.2014 | Page 16

Reminder: Plasma-Acceleration (Internal Injection) • This proved highly successful with electron bunches of . • Small dimensions involved � few ! • Highly compact but also accelerator: generation, bunching, focusing, acceleration, (wiggling) all in one small volume. • Energy spread and stability at the few % level. Ralph Aßmann | CAS | 27.11.2014 | Page 17

External Injection… Our Focus: External Injection of Known Beams... Ralph Aßmann | CAS | 27.11.2014 | Page 18

Foto Laser-Plasmabeschleuniger See lecture M. Kaluza 2013 0.05 mm 0.25 mm Metall (Kupfer) 100 mm S band Linac Struktur Mikro- Wellen zur Wellener- 500 mm zeugung Ralph Aßmann | CAS | 27.11.2014 | Page 19 SEITE 19

Wakefields a la Leonardo da Vinci in 1509… Ralph Aßmann | CAS | 27.11.2014 | Page 20 R. Assmann 20

The Linear Regime > Analytical treatment > Placement of beams in the plasma accelerating structure > Maximum acceleration (transformer ratio) > Optimizations: Energy spread, phase slippage, stability, reproducibility Ralph Aßmann | CAS | 27.11.2014 | Page 21

Linear Wakefields (R. Ruth / P. Chen 1986) ε = electrical field z = long. coord. r = radial coord. a = driver radius ω p = plasma frequency k p = plasma wave number t= time variable e= electron charge N= number e- drive bunch � ω = laser frequency τ = laser pulse length E 0 = laser electrical field m= mass of electron Can be analytically solved and treated. Here comparison beam-driven and laser-driven (beat wave). Ralph Aßmann | CAS | 27.11.2014 | Page 22

Linear Wakefields (R. Ruth / P. Chen 1986) Depends on Changes between accelerating Accelerating field radial position r and decelerating as function of longitudinal position z π /2 out of phase Transverse field Changes between focusing and defo- cusing as function of Depends on longitudinal position z radial position r Ralph Aßmann | CAS | 27.11.2014 | Page 23