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We present a novel ultrastable superconducting radio-frequency (RF) ion trap realized as a combination of an RF cavity and a linear Paul trap. Its RF quadrupole mode at 34.52 MHz reaches a quality factor of Q ≈ 2.3 × 105 at a temperature of 4.1 K and is used to radially confine ions in an ultralow-noise pseudopotential. This concept is expected to strongly suppress motional heating rates and related frequency shifts that limit the ultimate accuracy achieved in advanced ion traps for frequency metrology. Running with its low-vibration cryogenic cooling system, electron-beam ion trap, and deceleration beamline supplying highly charged ions (HCIs), the superconducting trap offers ideal conditions for optical frequency metrology with ionic species. We report its proof-of-principle operation as a quadrupole-mass filter with HCIs and trapping of Doppler-cooled 9Be+ Coulomb crystals.

We present a novel ultrastable superconducting radio-frequency (RF) ion trap realized as a combination of an RF cavity and a linear Paul trap. Its RF quadrupole mode at 34.52 MHz reaches a quality factor of Q ≈ 2.3 × 105 at a temperature of 4.1 K and is used to radially confine ions in an ultralow-noise pseudopotential. This concept is expected to strongly suppress motional heating rates and related frequency shifts that limit the ultimate accuracy achieved in advanced ion traps for frequency metrology. Running with its low-vibration cryogenic cooling system, electron-beam ion trap, and deceleration beamline supplying highly charged ions (HCIs), the superconducting trap offers ideal conditions for optical frequency metrology with ionic species. We report its proof-of-principle operation as a quadrupole-mass filter with HCIs and trapping of Doppler-cooled 9Be+ Coulomb crystals.

We tested the prototype DQW cavity in GERSEMI vertical test stand in FREIA. The performance metthe spec ification , and our experimental procedure and infrastructure are qualified for testing crab cavitiesi n the HL LHC project. This was the critic al milestone in the project and it also opens a newopportunity for testing superconducting cavities in FREIA.

We tested the prototype DQW cavity in GERSEMI vertical test stand in FREIA. The performance metthe spec ification , and our experimental procedure and infrastructure are qualified for testing crab cavitiesi n the HL LHC project. This was the critic al milestone in the project and it also opens a newopportunity for testing superconducting cavities in FREIA.

We tested the prototype DQW cavity in GERSEMI vertical test stand in FREIA. The performance metthe spec ification , and our experimental procedure and infrastructure are qualified for testing crab cavitiesi n the HL LHC project. This was the critic al milestone in the project and it also opens a newopportunity for testing superconducting cavities in FREIA.

We tested the prototype DQW cavity in GERSEMI vertical test stand in FREIA. The performance metthe spec ification , and our experimental procedure and infrastructure are qualified for testing crab cavitiesi n the HL LHC project. This was the critic al milestone in the project and it also opens a newopportunity for testing superconducting cavities in FREIA.

We tested the prototype DQW cavity in GERSEMI vertical test stand in FREIA. The performance metthe spec ification , and our experimental procedure and infrastructure are qualified for testing crab cavitiesi n the HL LHC project. This was the critic al milestone in the project and it also opens a newopportunity for testing superconducting cavities in FREIA.

As in 2007 the first 3.5 cell superconducting radio frequency (SRF) gun was taken into operation at the Helmholtz-Zentrum Dresden-Rossendorf (HZDR), it turned out that the specified performance to realize an electron energy gain of 9.4 MeV (E_peak=50 MV/m @ Q_0=1e10) has not been achieved. Instead, the resonator of the gun was limited by field emission to about one third of these values and the measured beam parameters remained significantly below the expectations. However, to demonstrate the full potential of this new electron source for the ELBE LINAC, a second and slightly modified SRF gun was developed and built in collaboration with Thomas Jefferson National Accelerator Facility (TJNAF). We will report on commissioning and first results of this new SRF gun. This includes in particular the characterization of the most important RF properties of the cavity as well as their comparison with previous vertical test results.

In January 2012 the 10 kW klystrons of the CW LINAC ELBE were replaced by pairs of 10kW solid state power amplifiers (SSPA). The talk gives an overview on the SSPA based ELBE RF system. The experience gained during the first two years of operation is reviewed.

Superconducting RF particle sources combine the advantages of normal conducting RF sources and high duty cycle non-RF sources. The Rossendorf SRF gun was the first to demonstrate this injecting electrons into the ELBE accelerator at 13MHz. Recently, a new 3-1/2-gun cavity has been prepared at Jefferson Lab for its use in an updated injector which is expected to increase the electron energy from 2:4 to 7:5 MeV. Along with this new cavity, a new gun cryostat has been introduced. It combines several minor updates to the setup with the installation of a superconducting solenoid right at the exit of the gun, compensating the emittance growth of the electron bunch at an early stage. Hereby, the results of the commissioning of the new cryostat including the solenoid are concluded and compared to the prior concept of using a normal conducting solenoid outside the cryostat. As it is of great importance to this subject, studies of the magnetic shielding are going to be presented as well.

Superconducting RF particle sources combine the advantages of normal conducting RF sources and high duty cycle non-RF sources. The Rossendorf SRF gun was the first to demonstrate this injecting electrons into the ELBE accelerator at 13MHz. Recently, a new 3-1/2-gun cavity has been prepared at Jefferson Lab for its use in an updated injector which is expected to increase the electron energy from 2:4 to 7:5 MeV. Along with this new cavity, a new gun cryostat has been introduced. It combines several minor updates to the setup with the installation of a superconducting solenoid right at the exit of the gun, compensating the emittance growth of the electron bunch at an early stage. Hereby, the results of the commissioning of the new cryostat including the solenoid are concluded and compared to the prior concept of using a normal conducting solenoid outside the cryostat. As it is of great importance to this subject, studies of the magnetic shielding are going to be presented as well.

As in 2007 the first 3.5 cell superconducting radio frequency (SRF) gun was taken into operation at the Helmholtz-Zentrum Dresden-Rossendorf (HZDR), it turned out that the specified performance to realize an electron energy gain of 9.4 MeV (E_peak=50 MV/m @ Q_0=1e10) has not been achieved. Instead, the resonator of the gun was limited by field emission to about one third of these values and the measured beam parameters remained significantly below the expectations. However, to demonstrate the full potential of this new electron source for the ELBE LINAC, a second and slightly modified SRF gun was developed and built in collaboration with Thomas Jefferson National Accelerator Facility (TJNAF). We will report on commissioning and first results of this new SRF gun. This includes in particular the characterization of the most important RF properties of the cavity as well as their comparison with previous vertical test results.

The transverse emittance is one of the most important quantities which characterize the quality of an electron source. For high quality experiments low beam emittance is required. By means of theoretical considerations and simulation calculations we have studied how the emittance of the Rossendorf superconducting radio-frequency photoelectron source (SRF gun) can be minimized. It turned out that neither a solenoid magnet nor the effect of space charge forces is needed to create a pronounced emittance minimum. The minimum appears by just adjusting the starting phase of the electron bunch with respect to the RF phase of the gun in a suitable way. Investigation of various correlations between the properties of the beam particles led to an explanation on how the minimum comes about. It is shown that the basic mechanism of minimization is the fact that the longitudinal properties of the particles (energy) are strongly influenced by the starting phase. Due to the coupling of the longitudinal and transverse degrees of freedom by the relativistic equation of motion the transverse degrees of freedom and thereby the emittance can be strongly influenced by the starting phase as well. The results obtained in this study will be applied to minimize the emittance in the commissioning phase of the SRF gun.

In January 2012 the 10 kW klystrons of the CW LINAC ELBE were replaced by pairs of 10kW solid state power amplifiers (SSPA). The talk gives an overview on the SSPA based ELBE RF system. The experience gained during the first two years of operation is reviewed.

The transverse emittance is one of the most important quantities which characterize the quality of an electron source. For high quality experiments low beam emittance is required. By means of theoretical considerations and simulation calculations we have studied how the emittance of the Rossendorf superconducting radio-frequency photoelectron source (SRF gun) can be minimized. It turned out that neither a solenoid magnet nor the effect of space charge forces is needed to create a pronounced emittance minimum. The minimum appears by just adjusting the starting phase of the electron bunch with respect to the RF phase of the gun in a suitable way. Investigation of various correlations between the properties of the beam particles led to an explanation on how the minimum comes about. It is shown that the basic mechanism of minimization is the fact that the longitudinal properties of the particles (energy) are strongly influenced by the starting phase. Due to the coupling of the longitudinal and transverse degrees of freedom by the relativistic equation of motion the transverse degrees of freedom and thereby the emittance can be strongly influenced by the starting phase as well. The results obtained in this study will be applied to minimize the emittance in the commissioning phase of the SRF gun.

The superconducting radio frequency photoinjector (SRF photoinjector) with Cs2Te cathode has been successfully operated under the collaboration of HZB, DESY, HZDR, and MBI. In order to improve the gradient of the gun cavity and the beam quality, a new modified SRF gun (SRF-gun 2008) has been designed. The main updates of the new cavity design for the new photoinjector were published before (SRF09 Conference Berlin). This cavity is being fabricated in Jefferson Lab. In this paper the new ideas of the further parts of the SRF-gun 2008 will be presented. The most important issue is the special design of half-cell and choke filter. The cathode cooler is also slightly changed, which simplifies the installation of the cathode cooler in the cavity. The next update is the separation of input and output of the liquid nitrogen supply, for the purpose of the stability of the nitrogen pressure as well as the better possibility of temperature measurement. Another key point is the implementation of the superconducting solenoid inside the cryomodule. The position of the solenoid can be accurately adjusted with two step motors, which are thermally isolated to the solenoid itself.

A superconducting radio-frequency (SRF) gun with a superconducting Pb photocathode was build up for the first stage of the BERLinPro gun. We report on the activities on the gun and measurements of the beam parameters like beam energy and beam current. Improvement of the quantum efficiency after the laser cleaning treatments is discussed.

The superconducting radio frequency photoinjector (SRF photoinjector) with Cs2Te cathode has been successfully operated under the collaboration of HZB, DESY, HZDR, and MBI. In order to improve the gradient of the gun cavity and the beam quality, a new modified SRF gun (SRF-gun 2008) has been designed. The main updates of the new cavity design for the new photoinjector were published before (SRF09 Conference Berlin). This cavity is being fabricated in Jefferson Lab. In this paper the new ideas of the further parts of the SRF-gun 2008 will be presented. The most important issue is the special design of half-cell and choke filter. The cathode cooler is also slightly changed, which simplifies the installation of the cathode cooler in the cavity. The next update is the separation of input and output of the liquid nitrogen supply, for the purpose of the stability of the nitrogen pressure as well as the better possibility of temperature measurement. Another key point is the implementation of the superconducting solenoid inside the cryomodule. The position of the solenoid can be accurately adjusted with two step motors, which are thermally isolated to the solenoid itself.

The superconducting radio frequency photoinjector (SRF photoinjector) with Cs2Te cathode has been successfully operated under the collaboration of HZB, DESY, HZDR, and MBI. In order to improve the gradient of the gun cavity and the beam quality, a new modified SRF gun (SRF-gun 2008) has been designed. The main updates of the new cavity design for the new photoinjector were published before (SRF09 Conference Berlin). This cavity is being fabricated in Jefferson Lab. In this paper the new ideas of the further parts of the SRF-gun 2008 will be presented. The most important issue is the special design of half-cell and choke filter. The cathode cooler is also slightly changed, which simplifies the installation of the cathode cooler in the cavity. The next update is the separation of input and output of the liquid nitrogen supply, for the purpose of the stability of the nitrogen pressure as well as the better possibility of temperature measurement. Another key point is the implementation of the superconducting solenoid inside the cryomodule. The position of the solenoid can be accurately adjusted with two step motors, which are thermally isolated to the solenoid itself.

A superconducting radio-frequency (SRF) gun with a superconducting Pb photocathode was build up for the first stage of the BERLinPro gun. We report on the activities on the gun and measurements of the beam parameters like beam energy and beam current. Improvement of the quantum efficiency after the laser cleaning treatments is discussed.

The RF-system of the superconducting electron linac ELBE (40 MeV, 1 mA CW) is in permanent operation since 2001, but it is not completely free of RF-trips. Experience gained within eight years of operation shows that the better the RF-components were conditioned the better is their electrical stability during long time operation. To be prepared for the planned ELBE upgrade with 16 kW of RF-power per cavity several test benches have been built to study the performance of RF-couplers and waveguide windows. In cooperation with Bruker BioSpin / France and CPI / USA the prototype of a 30 kW RF-amplifier based on an IOT had been tested with beam at ELBE. This paper gives an overview about tests of RF-components with increased RF-power at ELBE.

The RF-system of the superconducting electron linac ELBE (40 MeV, 1 mA CW) is in permanent operation since 2001, but it is not completely free of RF-trips. Experience gained within eight years of operation shows that the better the RF-components were conditioned the better is their electrical stability during long time operation. To be prepared for the planned ELBE upgrade with 16 kW of RF-power per cavity several test benches have been built to study the performance of RF-couplers and waveguide windows. In cooperation with Bruker BioSpin / France and CPI / USA the prototype of a 30 kW RF-amplifier based on an IOT had been tested with beam at ELBE. This paper gives an overview about tests of RF-components with increased RF-power at ELBE.

The RF-system of the superconducting electron linac ELBE (40 MeV, 1 mA CW) is in permanent operation since 2001, but it is not completely free of RF-trips. Experience gained within eight years of operation shows that the better the RF-components were conditioned the better is their electrical stability during long time operation. To be prepared for the planned ELBE upgrade with 16 kW of RF-power per cavity several test benches have been built to study the performance of RF-couplers and waveguide windows. In cooperation with Bruker BioSpin / France and CPI / USA the prototype of a 30 kW RF-amplifier based on an IOT had been tested with beam at ELBE. This paper gives an overview about tests of RF-components with increased RF-power at ELBE.