IOTA RF SYSTEM Kermit Carlson 13 Nov 14

RF System Specifications 1 kV RF gap potential 30 MHz CW for electron run – Provide acceleration potential 30 MHz CW for protons – Modulation for BPM measurements

ARF 4-3 Cavity from P-bar Accumulator 30 MHz Ferrite Loaded Cavity Tests

ARF 4’s Beampipe and Ceramic

Ferroxcube 4E2 Material Low permeability specialty NiZn ferrite only used in large toroids and machined products mainly for scientific particle accelerators operating at frequencies up to 100 MHz. SYMBOLCondition ValueUnit u i25C, < 0.25 mT 25 +/- 20% 25 C310mT C 350mT pDC, 25C~ 10^5M ohm Tc> 400 C Density4,000kG/m^3

Ferroxcube 4E2 Material Low permeability specialty NiZn ferrite only used in large toroids and machined products mainly for scientific particle accelerators operating at frequencies up to 100 MHz. Dimmension Outer Diameter 50 cm Inner Diameter 20 cm Thickness 25 mm

Ferroxcube 4E2 Material

ARF 4-3 Cavity from P-bar Accumulator 30 MHz Ferrite Loaded Cavity Tests Physical Cavity Dimensions Overall Length of Cavity37.75 Inches Diameter of Cavity28.0 Inches Ceramic Gap Length1.125 Inches Inner Beampipe Cover Diameter 6.0 Inches Beampipe Diameter4.0 Inches Center of Beamline to floor on present stand 29 Inches

ARF 4-3 Cavity from P-bar Accumulator 30 MHz Ferrite Loaded Cavity Tests

ARF 4-3 Cavity from P-bar Accumulator 30 MHz Ferrite Loaded Cavity Tests Predicted 4 FerritesPredicted 6 Ferrites Shunt Impedance Ohms Ohms Inductance0.534 uH0.843 uH Gap Capacitance33.3 pF R / Q111.0 Ohms138.5 Ohms B rf Max2.189 Gauss Power required for Egap = 1 kV rms75.0 Watts60.2 Watts

ARF 4-3 Cavity from P-bar Accumulator Ferrite Loaded Cavity Tests Type “4E2” Ferroxcube Ferrite disks

Capacitive tuning of gap resonance 3-30 pf 15 kV Vacuum variable Capacitor With one 4E2 Ferrite disk a capacitance of 3.8 pf was needed to lower the resonance from 32 to 30 Mhz Shorting vacuum relay shown disconnected

ARF 4-3 Cavity from P-bar Accumulator 30 MHz Ferrite Loaded Cavity Tests Coupling to the resonant structure can be accomplished in 3 main ways; Direct Connection from the input connector to the gap. A 50-Ohm water-cooled load can be connected to the feedpoint. A Capacitive Divider from the input connector to the gap An Inductive Coupling loop The coupling method can be designed to provide the required longitudinal Impedance for the accelerator design.

ARF 4-3 Cavity from P-bar Accumulator 30 MHz Ferrite Loaded Cavity Tests HP 4815A Vector Impedance Meter readout indicating a shunt impedance of 6,250 ohms at 30 Mhz with loading provided by a single Type-4E2 Ferrite disk.

ARF 4-3 Cavity from P-bar Accumulator 30 MHz Ferrite Loaded Cavity Tests Henry Amplifier Model 3000D Originally delivered to Fermilab tuned to 1.2 MHz, retuned to 2.5 MHz for use in the P-bar Accumulator, this amplifier can be retuned for use at 30 MHz for 1.5 kW output if a 50-Ohm gap impedance is required. Other amplifiers, that do not require retuning, are available if a higher gap impedance can be accomodated

Modification that was performed to prevent arcing of copper cooling disk channels when operating at 2.5 MHz and 10 kV gap Voltage

Testing of the ARF-4 Cavity at CMTF FREQUENCY 30 MHz R shunt 7,200 Ohms Q 100 Predicted RF Drive for 1 kV Gap Potential < 100 watts