PUBLICATION. Measurement setup at light source operational: Milestone M4.3

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1 CERN-ACC Future Circular Collider PUBLICATION Measurement setup at light source operational: Milestone M4.3 Perez, Francis (ALBA) et al. 24 August 2016 The European Circular Energy-Frontier Collider Study (EuroCirCol) project has received funding from the European Union s Horizon 2020 research and innovation programme under grant No The information herein only reflects the views of its authors and the European Commission is not responsible for any use that may be made of the information. The research leading to this document is part of the Future Circular Collider Study The electronic version of this FCC Publication is available on the CERN Document Server at the following URL : < CERN-ACC

2 Grant Agreement No: EuroCirCol European Circular Energy-Frontier Collider Study Horizon 2020 Research and Innovation Framework Programme, Research and Innovation Action MILESTONE REPORT MEASUREMENT SETUP AT LIGHT SOURCE Document identifier: Due date: End of Month 15 (September 2016) Report release date: 24/08/2016 Work package: Lead beneficiary: Document status: WP4 cryogenic beam vacuum system ALBA RELEASED Abstract: The design of the experimental setup for the measurements of the FCC-hh beam screen prototype to be installed at the ANKA lightsource has been completed and the alignment strategy and procedure has been validated by the CERN and KIT teams. In this report, a complete description of the setup and the program of measurements under different operation conditions is presented. Grant Agreement PUBLIC 1 / 15

3 Copyright notice: Copyright EuroCirCol Consortium, 2015 For more information on EuroCirCol, its partners and contributors please see The European Circular Energy-Frontier Collider Study (EuroCirCol) project has received funding from the European Union's Horizon 2020 research and innovation programme under grant No EuroCirCol began in June 2015 and will run for 4 years. The information herein only reflects the views of its authors and the European Commission is not responsible for any use that may be made of the information. Delivery Slip Name Partner Date Authored by Edited by Reviewed by Francis Perez Paolo Chiggiato Julie Hadre Johannes Gutleber Michael Benedikt Daniel Schulte ALBA CERN 27/07/16 CERN 02/08/16 CERN 09/08/16 Approved by EuroCirCol Coordination Committee 24/08/16 Grant Agreement PUBLIC 2 / 15

4 TABLE OF CONTENTS 1. MEASUREMENT SETUP ANKA LIGHT SOURCE FRONT END SETUP BEAM SCREEN PROTOTYPE DESIGN MEASUREMENT SETUP MEASUREMENT PROGRAM ANKA LIGTH SOURCE CONDITIONS TEST PROGRAM TESTS SCHEDULE CONCLUSIONS REFERENCES ANNEX: GLOSSARY Grant Agreement PUBLIC 3 / 15

5 1. MEASUREMENT SETUP The goal of the measurement setup is to determine the photodesorpotion yield, synchrotron radiation heat loads and photo-electrons generation inside the beam screen prototype. To this end, the prototype will be installed in a front end of the ANKA synchrotron ring and exposed to significant levels of synchrotron radiation, comparable to those expected at a 100 TeV hadron collider. The EuroCirCol project proposal foresaw installing the Coldex setup of CERN[1] at ANKA, but already at the beginning of the project it was realised that the Coldex setup was not available for the experiment. In order to be able to achieve the objective to experimentally determine the performance of the novel beam screen design, we decided to develop of dedicated setup specifically for the needs of the EuroCirCol project. After several design iterations we decided to limit the measurements to room temperature. This decision permits obtaining the required efficiency validation of the prototype at reduced complexity and cost. The design is, however, prepared for tests using liquid nitrogen as a coolant, at 77 K if needed ANKA LIGHT SOURCE ANKA is a synchrotron light source facility located in Karlsruhe, belonging to the Karlsruher Institut für Technologie (KIT). Synchrotron light is produced with an electron beam energy of 2.5 GeV and beam currents up to 200 ma (fig.1) [2]. ANKA can also be operated with lower electron energies down to 0.5 GeV. Figure.1: ANKA Light Source The decision to use ANKA for the test of the FCC-hh beam screen was taken due to the similarity of the synchrotron light emission with FCC-hh, in terms of beam power and light spectrum. In figure 2 it is shown the comparison of the emitted light at ANKA and the foreseen emission at FCC-hh [3]. Grant Agreement PUBLIC 4 / 15

6 Figure 2. Synchrotron light emission at ANKA and FCC-hh as a function of photon energy and for different FCC-hh proton energy (left: Flux, right: Power). Table I: ANKA parameters and requirements for EuroCirCol 1.2. FRONT END SETUP In order to be able to irradiate the beam screen prototype with appropriate synchrotron light, a port with bending magnets was chosen. The port has to have enough beam aperture for a wide radiation fan to reach the prototype and there should be enough space for the installation of the foreseen two meter long screen prototype. The chosen beam port is marked with a red dot in figure 3. Grant Agreement PUBLIC 5 / 15

7 Figure 3. Location of the chosen front end, marked by red dot. In December 2015 the installation of the needed equipment in the front end in order to allow the extraction of the synchrotron light and to isolate the experiment from the vacuum of the accelerator was performed (see figure 4). Photons with similar energy spectrum and power as expected to impinge on the FCC-hh arc vacuum chamber will be extracted by one of the ANKA bending magnets using a fixed aperture crotch absorber. An additional photon intensity absorber and a gate valve have been installed in the front end. The gate valve allows to install and exchange the test stand without breaking the vacuum integrity of the ANKA storage ring. In order to collimate the photons impinging on the beam screen horizontally and vertically, a slit system provided by KIT is placed after the gate valve. The installed equipment includes: - Crotch absorber, limiting the available photon aperture and absorbing the remaining sysnchrotron radiation power - Ion vacuum pump, in order to pump down the desorption in the absorber. - Vacuum gate valve, to isolate the storage ring vacuum from the experimental septup, allowing the installation and manipulation in the setup without affecting the accelerator vacuum level. Grant Agreement PUBLIC 6 / 15

8 Figure 4: Front end components as installed at ANKA and 3D drawing of the components 1.3. BEAM SCREEN PROTOTYPE DESIGN The vacuum beam screen for the FCC-hh is a complex structure, which has to fit in the bore of superconducting magnets working at 1.9 K and has to cope with synchrotron radiation power in the range of 30 W/m (i.e. more than 100 times the actual levels of LHC) generated by the proton beam at cryogenic temperatures while maintaining a gas density lower that H2/m 3 (i.e. five times lower that the actual levels of LHC). Figure 5 shows the drawing of the beam screen prototype with the indication of the dimensions, the different parts and its functions [4]. Figure 5. Prototype beam screen design for FCC-hh.. Left: 3D model. Rigth: Dimensions and functions. The main innovations of this design are the introduction of a photon deflector and an internal antechamber, with the objective of confining the photodesorbed molecules and electrons induced by Grant Agreement PUBLIC 7 / 15

9 the synchrotron radiation into the antechamber, where the pumping slots are located, isolating them from the actual beam pipe. In order to test the effectiveness of this design, a 2 meters long prototype is being produced for the test at ANKA. It will be water cooled at room temperature and installed inside a vacuum vessel. The income and outcome parts of the cooling tubes will be installed in such a way that flux of water is feasible through the cooling system without loosing UHV conditions. A central port will be used to communicate the interior part of the beam screen prototype with the diagnostic equipment necessary to perform photodesorption studies. Figure 6 shows the details of the proposal: the beam screen (top), the vacuum vessel, which will contain the beam screen (center) and the assembly where the vacuum port for pumping and diagnostics can be seen (bottom). Figure 6. Beam screen prototype for installation at ANKA. Top: Beam screen. Center: Vacuum vessel. Bottom: Assembly. Grant Agreement PUBLIC 8 / 15

10 1.4. MEASUREMENT SETUP The measurement setup is show in figure 7. It is composed of two main parts, the front end and the test bench, linked by a bellow. The front end part is equipped with the slits needed to fix the source size. The test bench part includes the beam screen prototype as well as several diagnostics components, such as pressure gauges, a residual gas analyser (RGA), temperature sensors and an electrode to be installed in front of a photon collector at the end of the beam screen. For alignment purposes two fluorescent screens will be used together with fiducial markers. Figure 8 shows the installation of the setup in the ANKA facility. Figure 7. Drawing with the different component of the test setup Figure 8. Implementation of the test setup in the ANKA facility Grant Agreement PUBLIC 9 / 15

11 2. MEASUREMENT PROGRAM The setup at ANKA will measure the following parameters of the beam screen prototype: - Photo desorption yields as a function of photon dose. The molecules desorbed inside the beam screen prototype by synchrotron radiation will be detected through the chimeney connected to te central port of the beam screen prototype by using a Bayard Alpert ion gauge and RGA quadrupole mass spectrometer in order to measure the induced pressure rise and to analize the composition of the desorbed gas. - Heat load distribution. A series of thermocouples will be installed along the beam screen prototype in the most critical regions of its design so that the thermal properties of the prototype can be qualified and the temperature distribution measured. - Reflectivity and efficiency of the photon deflector (see Figure 5) A positively biased electrode will be installed in front of the photon collector. The photoelectron current due to the irradiation with synchrotron radiation will be measured in two cases: a) direct incidence of the light into the collector, b) direct incidence of the light into the deflector of the beam screen prototype. The different ammount of photoelectrons generated at the collector will provide information about the light deflecting efficiency of the beam screen prototype. - Photoelectron yield. Copper strings will be placed in the inner part and all along the beam screen prototype. They will be electrically isolated from the beam screen prototype iself. By biasing the strings positively, photoelectrons will be measured as the synchrotron radiation impinges in the deflectors. Grant Agreement PUBLIC 10 / 15

12 2.1. ANKA LIGTH SOURCE CONDITIONS The ANKA light source will operate under its nominal conditions for emittance (defining the beam size and divergence) and energy (2.5 GeV [5]). Table II shows the nominal operation parameters. Table II: Nominal parameters of ANKA[5] The beam source parameters at the bending magnet are given in table III. Table III: Beam parameters at the bending source point Horizontal size 245 µm Horizontal divergence 179 µrad Vertical size 83 µm Vertical divergence 4 µrad Grant Agreement PUBLIC 11 / 15

13 2.2. TEST PROGRAM Prior to the test program, several preparation steps are needed: - Fiducilization of the equipment at CERN (Slits Fluorescent Screens, Photon Collector ) - Alignment of the beamscreen to ensure a proper knowledge of its position inside the chamber - Test of the setup at CERN - Transport and installation at ANKA - Alignment of the equipment at ANKA with a laser tracker - Test of the setup at ANKA The test program includes: - Desorption measurement as a function of the integrated dose - Thermal measurement as a function of beam current - Photoelectron emission studies - Reflectivity studies 2.3. TESTS SCHEDULE The test program spans from March 2017 until June 2018 with the following foreseen schedule. Grant Agreement PUBLIC 12 / 15

14 3. CONCLUSIONS Good progress has been achieved regarding the design of the test bench and preparation steps. The conceptual design as well as the drawings of the vacuum chambers that will contain the diagnostic equipment and the slits have been finalized. The procurement procedure of fluorescent screens, the photon collector and remaining equipment is being finalized. The slits that will fix the aperture of the synchrotron radiation impinging on the test bench and the borrowed motor controller boards were sent from KIT to CERN. The developement of the LabViewbased control system, has started. Its availability is criticial for the success of the tests. The test campaign will start with equipment testing in March Data acquisition and analysis will be carried out for one year, from May 2017 to June Grant Agreement PUBLIC 13 / 15

15 4. REFERENCES [1] [2] V. Baglin et al., First results from COLDEX applicable to the LHC cryogenic vacuum system, THP1B03, EPAC 00. H.O.Moser et al, "ANKA, a Synchrotron Light Source for Microstructure Fabrication and Analysis", Proceedings PAC95. [3] S.Casalbuoni et al, "FCC-hh Synchrotron Radiation Effects: The new ANKA facility for desorption measurement" [4] F.Perez and P.Chiggiato, 'Design, Prototyping and Tests of the FCC-hh Vacuum Beam Screen', presented at the FCC week 2016, Rome, Italy, [5] D.Einfeld et al. "Commissioning of the ANKA Storage Ring", Proceedings EPAC2000, Viena, Austria, Grant Agreement PUBLIC 14 / 15

16 ANNEX: GLOSSARY Acronym c.m. FCC FCC-hh FODO HE-LHC HL-LHC IBS IP KIT LHC Nb3Sn Nb-Ti RF RGA RMS SR SSC UHV Definition Centre of Mass Future Circular Collider Hadron Collider within the Future Circular Collider study Focusing and defocusing quadrupole lenses in alternating order High Energy - Large Hadron Collider High Luminosity Large Hadron Collider Intra Beam Scattering Interaction Point Karlsruher Institut für technologie Large Hadron Collider Niobium-tin, a metallic chemical Niobium-titanium, a superconducting alloy Radio Frequency Residual Gas Analizer Root Mean Square Synchrotron Radiation Superconducting Super Collider Ultra High Vacuum Grant Agreement PUBLIC 15 / 15