Power Supply Design Howie Pfeffer Mu 2 e

Power Supply Design Howie Pfeffer Mu 2 e Extinction Technical Design Review 2 November 2015

Basic Specifications (Eric, 9/30/15) Mu 2 e Magnet Specification Pole width [m] 0. 09 Pole gap [m] Length [m] 0. 8636 mu_0 1. 26 E-06 L [H] 5. 44 E-06 B/I [T/A] 7. 00 E-05 Frequency [k. Hz] 2 0. 018 N_cells Peak Field[Gauss] Peak Current [A] Peak Voltage [V] 300 3 162. 112089 2. 32 E+02 2. 38 E+03 4500 3 13. 8953219 1. 99 E+01 3. 05 E+03 Howie Pfeffer/Power Supply Design Power (W) 11/2/15

Power Supply Requirements • Minimize voltage-to-ground on magnets • Provide continuous 300 k. Hz excitation • Resonant system to minimize size and cost of power supply • Real time resonance control • Phase jump required 3 Howie Pfeffer/Power Supply Design 11/2/15

Power Supply Specifications 4 Howie Pfeffer/Power Supply Design 11/2/15

Load Parameters for 300 k. Hz Ø Ø Ø Total Magnet Inductance 16. 32 u. H Required Capacitance 18 n. F Total Losses 7. 20 E+03 watt (Magnet and capacitors) § Ø 5 Scaled from prototype magnet measurements (~ 1 k. W per ½ meter magnet. Cable losses about 1200 watts Howie Pfeffer/Power Supply Design 11/2/15

½ meter magnet resonant circuit testing 6 Howie Pfeffer/Power Supply Design 11/2/15

Approach Ø Use existing design Booster Corrector § 7 H-Bridge, Switch mode Power Supply Ø 3 -4 Supplies Required Ø Design/build/commission § Matching Transformer § PS Controls § Resonant Controls § Cabling Howie Pfeffer/Power Supply Design 11/2/15

Power Supply Block Diagram 232 Apk/61 Vpk 116 Apk/122 Vpk 8 Howie Pfeffer/Power Supply Design 11/2/15

H-Bridge, Switch-Mode Power Supply 9 Howie Pfeffer/Power Supply Design 11/2/15

Working Group Members 10 Howie Pfeffer/Power Supply Design 11/2/15

Modifications needed to operate a Booster corrector power supply at 300 k. H 1) Installed a larger DC - DC converter to power the bath tub driver for the FETs. 2) Changed the gate network from a resistive drive of 4. 7 ohms to a lower R (3. 3 ohms) in parallel with a diode. This decreases the gate turn on by a bit and makes the turn-off faster than the turn-on. 3) Built a low level drive circuit to accept a on-off drive from an square wave generator and create the on - off gate drive to both bridges with a 0. 2 usec delay between upper FET off to lower FET on. For reference the standard drive has a 0. 6 usec delay. 11 Howie Pfeffer/Power Supply Design 11/2/15

PS Testing A dummy load was fabricated from parts on hand. The parameters of the dummy load are L_series = 56. 5 u. H, C_series = 4. 95 n. F and R_series = 10 ohms. Thus: f_o = 1/2*pi*sqrt(L_s*C_s) = 301 k. Hz Q = (2*pi*f_o*L_s)/R_s = 10. 7 Conclusions: 1) Prototype unit is capable of driving a ~300 k. Hz load. 2) At a current of +/- 20 amps in the load you should expect about 20 deg. C rise of the air cooled heat sink. 3) With this measurement I would estimate that the unit could drive +/- 30 amps and deliver ~3, 000 watts to the load with a single unit. 4) Number of power supplies needed will depend on how far off resonance will be allowed during operation. 12 Howie Pfeffer/Power Supply Design 11/2/15

Modified booster corrector driving ½ meter prototype magnet Ø The required drive power increased from 1000 W to 1500 W over the span of 2 years. Ø This was tracked down to the resonant caps degrading. Ø Temperature measurements indicated that the PS could easily handle twice the power. 13 Howie Pfeffer/Power Supply Design 11/2/15

Real time resonance control Ø Measured stability of resonant frequency of prototype system was about +/- 0. 05 % over a period of 4 hours and a ferrite temperature range of 13 degrees C. Ø This corresponds to a +/- 0. 1% change in inductance or capacitance. Ø The data was taken after a 10 minute warm-up of the system. Ø An adjustable inductor of +/- 0. 7 u. H will allow for a resonant frequency change of +/- 0. 5%. This is ten times the change we have seen during our testing. 14 Howie Pfeffer/Power Supply Design 11/2/15

5. 1 MHz Testing ؽ Meter prototype magnet §I= 10 Apk, V=29 Vpk, 4 capacitors 0. 9 n. F each § 4: 1 Step-down transformer §Power = 145 watts §R at resonance = 2. 9 ohms §Input to transformer ~ 50 ohms Ø Extrapolated to the 3 -magnet system (20 Apk), § § § R at resonance = 7. 74 ohms 5: 2 step-down transformer Input to transformer ~50 ohms Only one RG 220 coax cable Drive power ~ 1547 watts § 3 x 2 x (2/3 * 2)2 x 145 15 Howie Pfeffer/Power Supply Design 11/2/15

16 Howie Pfeffer/Power Supply Design 5 MHz N c ar th m tr m C si ce m Magnet frequency response

½ meter prototype magnet model Calculated phase and amplitude of currents at different points in the ½ meter prototype magnet. 17 Howie Pfeffer/Power Supply Design 11/2/15

1 meter magnet model Calculated phase and amplitude of currents at different points in the 1 meter magnet. 18 Howie Pfeffer/Power Supply Design 11/2/15

Phase jump simulation, 300 k. Hz Phase 1 microsecond phase jump Magnet Current 19 Howie Pfeffer/Power Supply Design 1 m. S 11/2/15

Conclusions Ø Modified Booster corrector supplies are capable of driving the 300 k. Hz magnet system Ø Tuning of resonant frequency looks doable. Ø Phase jump looks doable Ø 4. 5 MHz magnet system can be driven by a 2 k. W RF amplifier. • Field varies along the length of the magnet but is not a problem. Ø Would like to measure the frequency response, inductance and losses in a new 1 -meter prototype magnet. 20 Howie Pfeffer/Power Supply Design 11/2/15