jacob rodnizki - Academia.edu (original) (raw)

Papers by jacob rodnizki

Energy and Energy Spread Measurements Using the Rutherford Scattering Technique for Tuning the Saraf

SARAF Phase-I HWR Coupler Cooling Design

The Soreq Applied Research Accelerator Facility (SARAF) design is based on a 40 MeV 5 mA light io... more The Soreq Applied Research Accelerator Facility (SARAF) design is based on a 40 MeV 5 mA light ions superconducting RF linac. Phase I of SARAF delivers up to 2 mA CW proton beam in an energy range of 1.5-4.5 MeV. The maximum beam power that we have reached is 4.5 kW. The warming of the SARAF linac RF couplers is currently the main limiting factor for reaching higher CW beam power. The coupler cooling configuration was optimized by increasing the cold window copper braid and adding a copper braid to the top end, using CST Multiphysics and ANSYS steady state and transient solvers. The study was conducted for the heat load generated by the surface currents of a matched 4 kW forward CW power, simulated by the CST MWS FD solver. Multipacting is a known potential heat source that overheats the coupler in the vicinity of the cold window. The coupler overheat phenomena was experimentally studied as a function of a DC bias voltage. It was found that a 900 V bias reduces significantly the hea...

Warming up of the coupler region of the SARAF Half Wave Resonator (HWR) cavities was one of the m... more Warming up of the coupler region of the SARAF Half Wave Resonator (HWR) cavities was one of the main limiting factors for long operation at high RF field values. The warming effect is, most likely, associated with multipacting in the coupler region. We have tried to suppress the multipacting discharge in the couplers by application a DC bias to their inner conductors. A bias-T, element that conducts up to 4 kW of 176 MHz RF power and provides DC insulation of the coupler inner conductor, was designed and built for this purpose. First on-line operation showed that the DC bias indeed reduces dramatically the warming rates of most of the cavities by an order of magnitude. Today, coupler warming is no longer the main factor hindering accelerator operation.

INTRODUCTION The SARAF radio-frequency quadrupole (RFQ) is a crucial element in the SARAF proton/... more INTRODUCTION The SARAF radio-frequency quadrupole (RFQ) is a crucial element in the SARAF proton/deuteron accelerator complex it makes acceleration of high intensity ion beams possible. The RFQ electrodes (Figure 1) consist of 4 four-meter long rods, with adjacent rods at opposite polarity and diagonal rods at same polarity, with the polarity oscillating sinusoidally at 176 MHz, thereby providing the element with very strong transverse focusing capabilities. In addition, properly designed longitudinal modulations on the electrode surfaces enable both acceleration and longitudinal focusing, and thereby the ability to bunch the beam. Bunching is a necessary feature for continuation of the acceleration with the superconducting halfwave resonators.

Phase I of the Soreq Applied Research Accelerator Facility, SARAF, has been installed and is curr... more Phase I of the Soreq Applied Research Accelerator Facility, SARAF, has been installed and is currently being commissioned at Soreq NRC [1]. According to the Phase I design, SARAF should yield 2 mA proton and deuteron beams at energies up to 4 and 5 MeV, respectively. The status of the main Phase I components is reported. We further present beam commissioning results, which include acceleration of a 1 mA CW proton beam up to 3 MeV. Further improvements in the facility in order to achieve the desired performance are discussed.

The Soreq Applied Research Accelerator Facility (SARAF) is built to be used for basic research, m... more The Soreq Applied Research Accelerator Facility (SARAF) is built to be used for basic research, medical research, neutron based non-destructive testing and radio-pharmaceuticals development and production. The accelerator, designed and constructed by Accel Instruments GmbH, starts with a 5 mA, 20 keV/u ECR ion source. A LEBT transports the beam and matches it to a normal-conducting 4-rod RFQ. The RFQ bunches the beam at a frequency of 176 MHz 4 mA ions and accelerate the ions to 1.5 MeV/u. A 0.65 m long MEBT transports and matches the beam into the superconducting linac. The 20 m long linac is composed of six cryostats that contain a total of 44 half-wave resonators optimized for 0=0.09 and 0.15, which are kept at a temperature of 4.5 K by liquid helium. In order to achieve the dose rate criterion for hands-on maintenance, beam loss is limited to 1 nA/m. Extensive beam dynamics simulations, including error analysis with high statistics, indicate that beam loss will indeed be below t...

The Soreq Applied Research Accelerator Facility (SARAF) design is based on a 40 MeV 5 mA light io... more The Soreq Applied Research Accelerator Facility (SARAF) design is based on a 40 MeV 5 mA light ions superconducting RF linac. Phase-I of SARAF delivers up to 2 mA CW proton beams in an energy range of 1.5 - 4.0 MeV. The maximum beam power that we have reached is 5.7 kW. Today, the main limiting factor to reach higher ion energy and beam power is related to the HWR sensitivity to the liquid helium coolant pressure fluctuations. The HWR sensitivity to helium pressure is about 60 Hz/mbar. The cavities had been designed, a decade ago, to be soft in order to enable tuning of their novel shape. However, the cavities turned out to be too soft. In this work we found that increasing the rigidity of the cavities in the vicinity of the external drift tubes may reduce the cavity sensitivity by a factor of three. A preliminary design to increase the cavity rigidity is presented.

SARAF Phase I linac in 2012

Journal of Instrumentation, 2014

This report outlines the status of beam operations at the SARAF accelerator during 2012. Performa... more This report outlines the status of beam operations at the SARAF accelerator during 2012. Performance of various accelerator subsystems, their limiting factors and the recent improvements are presented. The accumulated experience of proton beam operation is summarized. Future prospects are discussed.

Upgrade of the 4-rod radio frequency quadrupole for SARAF Phase II Linac

Journal of Instrumentation

The 176 MHz 4-rod radiofrequency quadrupole (RFQ) is the crucial part of the Soreq Applied Resear... more The 176 MHz 4-rod radiofrequency quadrupole (RFQ) is the crucial part of the Soreq Applied Research Accelerator Facility (SARAF) injector and must be able to operate at RF powers up to 190 kW continuous wave and transport 5 mA proton and deuteron beams. The SARAF Phase I RFQ is planned for use in Phase II. The period between the termination of Phase I and the installation of Phase II provided an opportunity to introduce RFQ improvements to fully meet the Phase II requirements. These upgrades and improvements are presented in this report together with the results of the recent conditioning campaigns.

Status of the CEA desing of the future Saraf linac (title to be revised)

A four gap OFHC copper rebuncher is developed at SNRC as a research study and a risk reduction fo... more A four gap OFHC copper rebuncher is developed at SNRC as a research study and a risk reduction for the MEBT of SARAF Phase II proton/ deuteron linac. The rebuncher is designed to bunch a 5 mA CW beam at 176 MHz. The required cavity voltage according to beam dynamics evaluation is 150 kV with a beam aperture diameter of 40 mm at a beam energy of 1.3 MeV/u with a Q value of 8000. Considering utilizing this cavity for enhancing the beam energy, the cooling configuration is explored for a cavity voltage of 300 kV, consuming 20 kW dissipated power, at a peak electric field of 16 MV/m, equivalent to the Kilpatrick limit. The electro magnetic study conducted with the CST RF simulation package was reproduced at ANSYS HFSS. The simulated dissipated power along the rebuncher for 20 kW forward power injected through the coupler port with the HFSS driven model were assigned to the ANSYS Fluent model to explore the resulted temperature map. Several evolved cooling configurations were studied, in...

SNRC and CEA collaborate to the upgrade of the SARAF Accelerator to 5 mA CW 40 MeV deuteron and p... more SNRC and CEA collaborate to the upgrade of the SARAF Accelerator to 5 mA CW 40 MeV deuteron and proton beams (Phase 2). This paper presents the reference design of the SARAF-LINAC Project including a four-vane 176 MHz RFQ, a MEBT and a superconducting linac made of four five-meter cryomodules housing 26 superconducting HWR cavities and 20 superconducting solenoids. The first two identical cryomodules house low-beta (βopt = 0.091), 280 mm long (flange to flange), 176 MHz HWR cavities, the two identical last cryomodules house high-beta (βopt = 0.181), 410 mm long, 176 MHz, HWR cavities. The beam is focused with superconducting solenoids located between cavities housing steering coils. A BPM is placed upstream each solenoid.

Acceleration of a 1mA Continuous Wave (CW) deuteron (A/Q=2) beam at SARAF has been accomplished f... more Acceleration of a 1mA Continuous Wave (CW) deuteron (A/Q=2) beam at SARAF has been accomplished for the first time. A 5.3 mA pulsed deuteron beam has been accelerated as well. These achievements cap a series of major modifications to the Radio Frequency Quadrupole (RFQ) 4-rods structure which included the incorporation of a new end flange, introduction of an additional RF power coupler and, most recently, installation of a new set of rod electrodes. The new rod modulation has been designed to enable deuteron beam acceleration at a lower inter-electrode voltage, to a slightly reduced final energy of 1.27 MeV/u and with stringent constraints on the extant of beam tails in the longitudinal phase space. This report will focus primarily on the installation and testing of the new rods. The successful conditioning campaign to 200 kW, ~10% above than the working point for deuteron operation, will be described. Beam commissioning with proton and deuteron beams will also be detailed. Results ...

SNRC and CEA collaborate to the upgrade of the SARAF accelerator to 5 mA CW 40 MeV deuteron and p... more SNRC and CEA collaborate to the upgrade of the SARAF accelerator to 5 mA CW 40 MeV deuteron and proton beams (Phase 2). CEA is in charge of the design, construction and commissioning of the MEBT line and the superconducting linac (SARAF-LINAC Project). The prototypes of the 176 MHz NC rebuncher, SC cavities, RF coupler and SC Solenoid-Package are under construction and their test stands construction or adaptation is in progress at Saclay. Meanwhile, the cryomodules and the global system just passed their Critical Design Reviews. This paper presents the status of the SARAF-LINAC Project at April 2018. INTRODUCTION The SARAF-LINAC project, managed by CEA (France), integrated to the SARAF-Phase 2 project managed by SNRC (Israel) has been introduced in [1]. In 2014, a first System Design Report was presented and served of basis on an agreement between CEA and SNRC. The < 8 year project can be simplified in 3 overlapping phases (Fig. 1):  ~3 years of detailed design, including protot...

The Soreq Applied Research Accelerator Facility (SARAF) is built as a user facility. An intense f... more The Soreq Applied Research Accelerator Facility (SARAF) is built as a user facility. An intense fast neutrons source, a thermal neutrons source and apparatuses for production of isotopes for basic and applied research will be available at the end of construction, foreseen in several years. SARAF is based on a high intensity CW proton / deuteron RF superconducting linear accelerator. Several novel technologies are used in order to build this demanding linac. To reduce technological risks, the construction was divided in two Phases. Phase-I was constructed in order to test and characterize the novel technologies and is in routine operation since 2010. SARAF phase-I, with its single 6 half-wave resonators separated vacuum cryomodule, is the first high current, superconducting low-beta linac in operation and it is presently delivering CW mA proton beams for target developments. Phase-II of this linac will allow acceleration up to 40 MeV and 5 mA CW proton and deuteron beams. Phase-II is...

The SARAF 3.8 m long 4-rod RFQ is able to accelerate 4mA CW proton beam to 1.5 MeV. During the la... more The SARAF 3.8 m long 4-rod RFQ is able to accelerate 4mA CW proton beam to 1.5 MeV. During the last years several experiments with CW proton beam up to 2 mA and in the range of 1.9-4 MeV were run at SARAF linac. The conditions for running CW deuteron beams (250 kW CW dissipated power or a 65 kV inter-rod voltage) have not been achieved yet. Our findings imply that the RFQ coupler was the primary bottle neck. Thus, a project to split the RFQ power line was initiated. In the framework of the project, a 3 dB splitter and two new RF couplers were installed. The RF couplers were manufactured in-house according to an improved design which included better brazing methods and better vacuum and RF sealing. This project is innovative from two points of view: (a) Implementation of two couplers located in two separated RF cells in a 4-rod RFQ. Synchronization of the incident power phase in both couplers was achieved by a single LLRF control channel and phase matching was achieved by adjusting the length of the RF rigid lines. (b) RFQ availability at 200 kW CW was demonstrated. This power range is sufficient for acceleration of a high intensity 5 mA CW deuteron beam to 1.3 MeV/u by a new modulation of the RFQ rods. To our knowledge, SARAF RFQ will be the first 4-rod RFQ capable of running a CW deuteron beam.

Submitted for …, 2008

We present a new approach for beam loss calculations that places emphasis on the tails of the par... more We present a new approach for beam loss calculations that places emphasis on the tails of the particle distributions. This scheme is used for simulating the SARAF proton/deuteron accelerator, a 176 MHz RF linac complex consisting of a 4-rod RFQ and 44 SC half wave resonator (HWR) cavities designed to operate in CW mode at 4 mA beam current. We discuss our scheme for highlighting the tails of the particle bunches generated by the RFQ. Simulation of the RFQ and RF linac with the tail emphasis technique allows ...

SARAF Phase I linac operation in 2013–2014

Journal of Instrumentation, 2015

Phase I of the SARAF superconducting RF linac is under operation at the Soreq Nuclear Research Ce... more Phase I of the SARAF superconducting RF linac is under operation at the Soreq Nuclear Research Center. The present status of Phase I main components is reported, as well as, the beam operation experience accumulated in 2013–2014. The latter include acceleration of a 2 mA and 1.6 mA CW proton beams at energies of 2 MeV and 3.9 MeV correspondingly and 1 mA pulsed, duty cycle of few %, deuteron beams up to 5.6 MeV. The recent experiments include operation of intense CW proton beams on the liquid lithium target.

SARAF Phase-I linac is the first accelerator to demonstrate acceleration of variable energy 2 mA ... more SARAF Phase-I linac is the first accelerator to demonstrate acceleration of variable energy 2 mA CW proton beam. Such intense beam is used in SARAF Phase-I to irradiate a liquid lithium jet target for nuclear astrophysics studies. Several improvements were necessary to allow beam operation with such high current. The improvements include a DC bias that was introduced on the cavity RF coupler to reduce coupler heating. A new slow chopper was commissioned to enable increase the current by increasing the duty cycle with fewer changes in the beam optics. A beam dump was developed to allow beam studies of a 2 mA CW proton beam. The beam dump is based on tungsten pins which distributes, by radiation, the high beam power over a large area which is then easily water cooled. While most of beam tuning is done using a low intensity pilot beam, some nondestructive methods were studied to monitor the high intensity beam. These include a current transformer and a residual gas monitor (RGM) to mon...

Energy and Energy Spread Measurements Using the Rutherford Scattering Technique for Tuning the Saraf

SARAF Phase-I HWR Coupler Cooling Design

The Soreq Applied Research Accelerator Facility (SARAF) design is based on a 40 MeV 5 mA light io... more The Soreq Applied Research Accelerator Facility (SARAF) design is based on a 40 MeV 5 mA light ions superconducting RF linac. Phase I of SARAF delivers up to 2 mA CW proton beam in an energy range of 1.5-4.5 MeV. The maximum beam power that we have reached is 4.5 kW. The warming of the SARAF linac RF couplers is currently the main limiting factor for reaching higher CW beam power. The coupler cooling configuration was optimized by increasing the cold window copper braid and adding a copper braid to the top end, using CST Multiphysics and ANSYS steady state and transient solvers. The study was conducted for the heat load generated by the surface currents of a matched 4 kW forward CW power, simulated by the CST MWS FD solver. Multipacting is a known potential heat source that overheats the coupler in the vicinity of the cold window. The coupler overheat phenomena was experimentally studied as a function of a DC bias voltage. It was found that a 900 V bias reduces significantly the hea...

Warming up of the coupler region of the SARAF Half Wave Resonator (HWR) cavities was one of the m... more Warming up of the coupler region of the SARAF Half Wave Resonator (HWR) cavities was one of the main limiting factors for long operation at high RF field values. The warming effect is, most likely, associated with multipacting in the coupler region. We have tried to suppress the multipacting discharge in the couplers by application a DC bias to their inner conductors. A bias-T, element that conducts up to 4 kW of 176 MHz RF power and provides DC insulation of the coupler inner conductor, was designed and built for this purpose. First on-line operation showed that the DC bias indeed reduces dramatically the warming rates of most of the cavities by an order of magnitude. Today, coupler warming is no longer the main factor hindering accelerator operation.

INTRODUCTION The SARAF radio-frequency quadrupole (RFQ) is a crucial element in the SARAF proton/... more INTRODUCTION The SARAF radio-frequency quadrupole (RFQ) is a crucial element in the SARAF proton/deuteron accelerator complex it makes acceleration of high intensity ion beams possible. The RFQ electrodes (Figure 1) consist of 4 four-meter long rods, with adjacent rods at opposite polarity and diagonal rods at same polarity, with the polarity oscillating sinusoidally at 176 MHz, thereby providing the element with very strong transverse focusing capabilities. In addition, properly designed longitudinal modulations on the electrode surfaces enable both acceleration and longitudinal focusing, and thereby the ability to bunch the beam. Bunching is a necessary feature for continuation of the acceleration with the superconducting halfwave resonators.

Phase I of the Soreq Applied Research Accelerator Facility, SARAF, has been installed and is curr... more Phase I of the Soreq Applied Research Accelerator Facility, SARAF, has been installed and is currently being commissioned at Soreq NRC [1]. According to the Phase I design, SARAF should yield 2 mA proton and deuteron beams at energies up to 4 and 5 MeV, respectively. The status of the main Phase I components is reported. We further present beam commissioning results, which include acceleration of a 1 mA CW proton beam up to 3 MeV. Further improvements in the facility in order to achieve the desired performance are discussed.

The Soreq Applied Research Accelerator Facility (SARAF) is built to be used for basic research, m... more The Soreq Applied Research Accelerator Facility (SARAF) is built to be used for basic research, medical research, neutron based non-destructive testing and radio-pharmaceuticals development and production. The accelerator, designed and constructed by Accel Instruments GmbH, starts with a 5 mA, 20 keV/u ECR ion source. A LEBT transports the beam and matches it to a normal-conducting 4-rod RFQ. The RFQ bunches the beam at a frequency of 176 MHz 4 mA ions and accelerate the ions to 1.5 MeV/u. A 0.65 m long MEBT transports and matches the beam into the superconducting linac. The 20 m long linac is composed of six cryostats that contain a total of 44 half-wave resonators optimized for 0=0.09 and 0.15, which are kept at a temperature of 4.5 K by liquid helium. In order to achieve the dose rate criterion for hands-on maintenance, beam loss is limited to 1 nA/m. Extensive beam dynamics simulations, including error analysis with high statistics, indicate that beam loss will indeed be below t...

The Soreq Applied Research Accelerator Facility (SARAF) design is based on a 40 MeV 5 mA light io... more The Soreq Applied Research Accelerator Facility (SARAF) design is based on a 40 MeV 5 mA light ions superconducting RF linac. Phase-I of SARAF delivers up to 2 mA CW proton beams in an energy range of 1.5 - 4.0 MeV. The maximum beam power that we have reached is 5.7 kW. Today, the main limiting factor to reach higher ion energy and beam power is related to the HWR sensitivity to the liquid helium coolant pressure fluctuations. The HWR sensitivity to helium pressure is about 60 Hz/mbar. The cavities had been designed, a decade ago, to be soft in order to enable tuning of their novel shape. However, the cavities turned out to be too soft. In this work we found that increasing the rigidity of the cavities in the vicinity of the external drift tubes may reduce the cavity sensitivity by a factor of three. A preliminary design to increase the cavity rigidity is presented.

SARAF Phase I linac in 2012

Journal of Instrumentation, 2014

This report outlines the status of beam operations at the SARAF accelerator during 2012. Performa... more This report outlines the status of beam operations at the SARAF accelerator during 2012. Performance of various accelerator subsystems, their limiting factors and the recent improvements are presented. The accumulated experience of proton beam operation is summarized. Future prospects are discussed.

Upgrade of the 4-rod radio frequency quadrupole for SARAF Phase II Linac

Journal of Instrumentation

The 176 MHz 4-rod radiofrequency quadrupole (RFQ) is the crucial part of the Soreq Applied Resear... more The 176 MHz 4-rod radiofrequency quadrupole (RFQ) is the crucial part of the Soreq Applied Research Accelerator Facility (SARAF) injector and must be able to operate at RF powers up to 190 kW continuous wave and transport 5 mA proton and deuteron beams. The SARAF Phase I RFQ is planned for use in Phase II. The period between the termination of Phase I and the installation of Phase II provided an opportunity to introduce RFQ improvements to fully meet the Phase II requirements. These upgrades and improvements are presented in this report together with the results of the recent conditioning campaigns.

Status of the CEA desing of the future Saraf linac (title to be revised)

A four gap OFHC copper rebuncher is developed at SNRC as a research study and a risk reduction fo... more A four gap OFHC copper rebuncher is developed at SNRC as a research study and a risk reduction for the MEBT of SARAF Phase II proton/ deuteron linac. The rebuncher is designed to bunch a 5 mA CW beam at 176 MHz. The required cavity voltage according to beam dynamics evaluation is 150 kV with a beam aperture diameter of 40 mm at a beam energy of 1.3 MeV/u with a Q value of 8000. Considering utilizing this cavity for enhancing the beam energy, the cooling configuration is explored for a cavity voltage of 300 kV, consuming 20 kW dissipated power, at a peak electric field of 16 MV/m, equivalent to the Kilpatrick limit. The electro magnetic study conducted with the CST RF simulation package was reproduced at ANSYS HFSS. The simulated dissipated power along the rebuncher for 20 kW forward power injected through the coupler port with the HFSS driven model were assigned to the ANSYS Fluent model to explore the resulted temperature map. Several evolved cooling configurations were studied, in...

SNRC and CEA collaborate to the upgrade of the SARAF Accelerator to 5 mA CW 40 MeV deuteron and p... more SNRC and CEA collaborate to the upgrade of the SARAF Accelerator to 5 mA CW 40 MeV deuteron and proton beams (Phase 2). This paper presents the reference design of the SARAF-LINAC Project including a four-vane 176 MHz RFQ, a MEBT and a superconducting linac made of four five-meter cryomodules housing 26 superconducting HWR cavities and 20 superconducting solenoids. The first two identical cryomodules house low-beta (βopt = 0.091), 280 mm long (flange to flange), 176 MHz HWR cavities, the two identical last cryomodules house high-beta (βopt = 0.181), 410 mm long, 176 MHz, HWR cavities. The beam is focused with superconducting solenoids located between cavities housing steering coils. A BPM is placed upstream each solenoid.

Acceleration of a 1mA Continuous Wave (CW) deuteron (A/Q=2) beam at SARAF has been accomplished f... more Acceleration of a 1mA Continuous Wave (CW) deuteron (A/Q=2) beam at SARAF has been accomplished for the first time. A 5.3 mA pulsed deuteron beam has been accelerated as well. These achievements cap a series of major modifications to the Radio Frequency Quadrupole (RFQ) 4-rods structure which included the incorporation of a new end flange, introduction of an additional RF power coupler and, most recently, installation of a new set of rod electrodes. The new rod modulation has been designed to enable deuteron beam acceleration at a lower inter-electrode voltage, to a slightly reduced final energy of 1.27 MeV/u and with stringent constraints on the extant of beam tails in the longitudinal phase space. This report will focus primarily on the installation and testing of the new rods. The successful conditioning campaign to 200 kW, ~10% above than the working point for deuteron operation, will be described. Beam commissioning with proton and deuteron beams will also be detailed. Results ...

SNRC and CEA collaborate to the upgrade of the SARAF accelerator to 5 mA CW 40 MeV deuteron and p... more SNRC and CEA collaborate to the upgrade of the SARAF accelerator to 5 mA CW 40 MeV deuteron and proton beams (Phase 2). CEA is in charge of the design, construction and commissioning of the MEBT line and the superconducting linac (SARAF-LINAC Project). The prototypes of the 176 MHz NC rebuncher, SC cavities, RF coupler and SC Solenoid-Package are under construction and their test stands construction or adaptation is in progress at Saclay. Meanwhile, the cryomodules and the global system just passed their Critical Design Reviews. This paper presents the status of the SARAF-LINAC Project at April 2018. INTRODUCTION The SARAF-LINAC project, managed by CEA (France), integrated to the SARAF-Phase 2 project managed by SNRC (Israel) has been introduced in [1]. In 2014, a first System Design Report was presented and served of basis on an agreement between CEA and SNRC. The < 8 year project can be simplified in 3 overlapping phases (Fig. 1):  ~3 years of detailed design, including protot...

The Soreq Applied Research Accelerator Facility (SARAF) is built as a user facility. An intense f... more The Soreq Applied Research Accelerator Facility (SARAF) is built as a user facility. An intense fast neutrons source, a thermal neutrons source and apparatuses for production of isotopes for basic and applied research will be available at the end of construction, foreseen in several years. SARAF is based on a high intensity CW proton / deuteron RF superconducting linear accelerator. Several novel technologies are used in order to build this demanding linac. To reduce technological risks, the construction was divided in two Phases. Phase-I was constructed in order to test and characterize the novel technologies and is in routine operation since 2010. SARAF phase-I, with its single 6 half-wave resonators separated vacuum cryomodule, is the first high current, superconducting low-beta linac in operation and it is presently delivering CW mA proton beams for target developments. Phase-II of this linac will allow acceleration up to 40 MeV and 5 mA CW proton and deuteron beams. Phase-II is...

The SARAF 3.8 m long 4-rod RFQ is able to accelerate 4mA CW proton beam to 1.5 MeV. During the la... more The SARAF 3.8 m long 4-rod RFQ is able to accelerate 4mA CW proton beam to 1.5 MeV. During the last years several experiments with CW proton beam up to 2 mA and in the range of 1.9-4 MeV were run at SARAF linac. The conditions for running CW deuteron beams (250 kW CW dissipated power or a 65 kV inter-rod voltage) have not been achieved yet. Our findings imply that the RFQ coupler was the primary bottle neck. Thus, a project to split the RFQ power line was initiated. In the framework of the project, a 3 dB splitter and two new RF couplers were installed. The RF couplers were manufactured in-house according to an improved design which included better brazing methods and better vacuum and RF sealing. This project is innovative from two points of view: (a) Implementation of two couplers located in two separated RF cells in a 4-rod RFQ. Synchronization of the incident power phase in both couplers was achieved by a single LLRF control channel and phase matching was achieved by adjusting the length of the RF rigid lines. (b) RFQ availability at 200 kW CW was demonstrated. This power range is sufficient for acceleration of a high intensity 5 mA CW deuteron beam to 1.3 MeV/u by a new modulation of the RFQ rods. To our knowledge, SARAF RFQ will be the first 4-rod RFQ capable of running a CW deuteron beam.

Submitted for …, 2008

We present a new approach for beam loss calculations that places emphasis on the tails of the par... more We present a new approach for beam loss calculations that places emphasis on the tails of the particle distributions. This scheme is used for simulating the SARAF proton/deuteron accelerator, a 176 MHz RF linac complex consisting of a 4-rod RFQ and 44 SC half wave resonator (HWR) cavities designed to operate in CW mode at 4 mA beam current. We discuss our scheme for highlighting the tails of the particle bunches generated by the RFQ. Simulation of the RFQ and RF linac with the tail emphasis technique allows ...

SARAF Phase I linac operation in 2013–2014

Journal of Instrumentation, 2015

Phase I of the SARAF superconducting RF linac is under operation at the Soreq Nuclear Research Ce... more Phase I of the SARAF superconducting RF linac is under operation at the Soreq Nuclear Research Center. The present status of Phase I main components is reported, as well as, the beam operation experience accumulated in 2013–2014. The latter include acceleration of a 2 mA and 1.6 mA CW proton beams at energies of 2 MeV and 3.9 MeV correspondingly and 1 mA pulsed, duty cycle of few %, deuteron beams up to 5.6 MeV. The recent experiments include operation of intense CW proton beams on the liquid lithium target.

SARAF Phase-I linac is the first accelerator to demonstrate acceleration of variable energy 2 mA ... more SARAF Phase-I linac is the first accelerator to demonstrate acceleration of variable energy 2 mA CW proton beam. Such intense beam is used in SARAF Phase-I to irradiate a liquid lithium jet target for nuclear astrophysics studies. Several improvements were necessary to allow beam operation with such high current. The improvements include a DC bias that was introduced on the cavity RF coupler to reduce coupler heating. A new slow chopper was commissioned to enable increase the current by increasing the duty cycle with fewer changes in the beam optics. A beam dump was developed to allow beam studies of a 2 mA CW proton beam. The beam dump is based on tungsten pins which distributes, by radiation, the high beam power over a large area which is then easily water cooled. While most of beam tuning is done using a low intensity pilot beam, some nondestructive methods were studied to monitor the high intensity beam. These include a current transformer and a residual gas monitor (RGM) to mon...